Camellia sinensis), with adverse effects on plant growth and development and subsequent negative impacts on the tea industry. Methyl jasmonate (MeJA), as a plant inducer, can improve the cold-stress tolerance in tea plants. R2R3-MYB transcription factors (TFs) are considered potentially important regulators in the resistance to cold stress in plants. However, the molecular mechanisms, by which MYB TFs via the jasmonic acid pathway respond to cold stress in the tea plant, remain unknown. In this study, physiological and biochemical assays showed that exogenous MeJA application could effectively promote ROS scavenging in the tea plant under cold stress, maintaining the stability of the cell membrane. Sixteen R2R3-MYB TFs genes were identified from the tea plant genome database. Quantitative RT-PCR analysis showed that three CsMYB genes were strongly induced under a combination of MeJA and cold-stress treatment. Subcellular localization assays suggest CsMYB45, CsMYB46, and CsMYB105 localized in the nucleus. Exogenous MeJA treatment enhanced the overexpression of CsMYB45, CsMYB46, and CsMYB105 in E. coli and improved the growth and survival rates of recombinant cells compared to an empty vector under cold stress. Yeast two-hybrid and bimolecular fluorescence complementation experiments confirmed that CsMYB46 and CsMYB105 interacted with CsJAZ3, CsJAZ10, and CsJAZ11 in the nucleus. Taken together, these results highlight that CsMYB45, CsMYB46, and CsMYB105 are not only key components in the cold-stress signal response pathway but also may serve as points of confluence for cold stress and JA signaling pathways. Furthermore, our findings provide new insight into how MYB TFs influence cold tolerance via the jasmonic acid pathway in tea and provide candidate genes for future functional studies and breeding.Low-temperature stress is an increasing problem for the cultivation of tea ( Camellia sinensis (L.) O. Kuntze) is an economically important perennial evergreen woody crop distributed in tropical to temperate regions [The tea plant  are a type of lipid-derived phytohormone, which include jasmonic acid and its derivatives, such as methyl jasmonate (MeJA), jasmonoyl-isoleucine (JA-Ile), and 12-OH-JA ,4. Increynthesis ,11,12,13Arabidopsis [Zea mays) [Oryza sativa) [Glycine max Merri) [Malus domestica) [Camellia sinensis) [MdMYB23 improved the cold tolerance in transgenic apple calli and Arabidopsis [GmMYB76 and GmMYB177 enhanced the cold tolerance of soybeans. A previous study indicated that overexpression of SIGMYBL2 improved cold resistance in tobacco [FtMYB3 was induced by exogenous MeJA treatment and responded to cold stress by altering anthocyanin biosynthesis [OsMYB2, OsMYB3R-2, OsMYB4, and OsMYBS3 are also involved in modulating the cold-stress response [The MYB transcription factor family is widely presented in all eukaryotes, and they are functionally diverse and constitute one of the largest protein families in plants. MYB TFs contain one to four highly conserved MYB DNA-binding domain repeats (R), which are classified into the 1R, R2R3, R1R2R3, and 4R MYB subfamilies. The R2R3 MYB TFs are the largest MYB subfamily and are involved in various processes, including primary and secondary metabolism, development, hormone regulation pathways, and responses to biotic and abiotic stresses . Differebidopsis , maize (ea mays) , rice (O sativa) , soybeanx Merri) , apple (mestica) , and teainensis) . Chen etinensis) . Overexpbidopsis , while o tobacco . In Tartynthesis . In riceresponse ,25. Arabidopsis thaliana [Arabidopsis, yeast two-hybrid assays indicated that MYB21 and MYB24 interact with JAZ 1/8/11 to mediate various jasmonate-regulated processes, including fertility, root growth, anthocyanin accumulation, senescence, and defense [MdMYB24, which is involved in the regulation of JA-induced anthocyanin biosynthesis in apple [OsMYB30 negatively regulated BMY (beta-amylase) genes by interacting with OsJAZ9 to fine-tune starch breakdown and maltose content, thereby improving the cold tolerance in rice [FtMYB3 interacted with FtJAZ2, playing a role in anthocyanin biosynthesis under cold stress [FtMYB18 mediated the inhibition of anthocyanin and PA synthesis by forming an MBW transcriptional complex with FtTT8 and FtTTG1 and an MYB-JAZ complex with FtJAZ1/-3/-4/-7 in Tartary buckwheat [JAZ and MYB genes can directly or indirectly form a complex to respond to cold stress in plants.MYB TFs can also participate in JA reaction processes, mainly by promoting the synthesis of anthocyanins and other substances to improve plant cold resistance. In JA-triggered signal transduction, the inhibitor JAZ in the SCFCOI1-JAZ ubiquitin proteasome degradation pathway plays a core role , and thethaliana . In Arab defense . Wang etin apple . OsMYB30 in rice . In Tartd stress . An et ad stress . MYB prod stress . Similard stress . FtMYB18uckwheat . Taken tEctropis grisescens, mainly by reducing the accumulation of (-)epicatechin and (-)-epigallocatechin through repression of the JA signaling pathway [Ectropis grisescens) [MeJA is an efficient elicitor that can trigger the biosynthesis of volatile and nonvolatile secondary metabolites. Exogenous MeJA application has been widely used to improve the quality of horticultural crops. Examples of fruits with a flavor that has been enhanced after exogenous MeJA treatment include peach , strawbe pathway . Exogenosescens) . HoweverFour indicators, including the contents of proline, soluble sugar, malondialdehyde (MDA), and relative electrolyte leakage (REL), reflect the degree of membrane damage caused by cold stress A. ProlinIn this study, we found that the anthocyanin content was significantly higher in T2, T3, T4, T5, and T6 than in CK. The anthocyanin content of T6 was 1.75 times higher than that of CK. However, the anthocyanin content of T1 was significantly lower than that of CK. Similarly, chlorophyll content was clearly higher in T1 than in CK but lower in the other five treatments. The endogenous MeJA content in T4 was 3.89 ng/g, significantly higher than that of CK (1.89 ng/g). In the other treatments, the endogenous MeJA content was clearly lower than that in CK. However, the endogenous MeJA contents in the T5 and T6 treatments were significantly higher than those in the T1 and T2 treatments, respectively B.The SOD activity of T5 was significantly higher than that of CK. The POD activity was significantly higher in T2, T3, T4, T5, and T6 than in CK and T1. Among of them, the POD activities under T3 exhibited a two-fold increase. CAT activity was significantly higher in T2, T3, T4, T5, and T6 than in CK and showed the highest value in T2. Polyphenol Oxidase (PPO) activity was significantly increased only in T4, in which it was 1.26 times higher than in CK. Our results indicated that PPO activity was significantly lower in T2, T5, and T6 than in CK. Phenylalanine ammonia lyase (PAL) activity was significantly higher in T6 and lower in T2 than in CK. Compared with CK, cinnamate 4-hydroxylase (C4H) activity was significantly higher in T1, T4, and T6 but showed no significant differences in T2, T3, and T5 C.MYB genes in apical bud and young leaf tissues of the tea variety ‘Shuchazao’ in response to MeJA treatment and low temperature, were analyzed  and exogenous MeJA alone (T3 and T4) (p < 0.05). CsMYB46 expression was significantly higher in T2, T3, T5, and T6 (combined cold-stress and exogenous MeJA treatments) than in CK (p < 0.05). Similarly, CsMYB105 expression was significantly higher in T1, T2, T3, T4, and T6 than in CK (p < 0.05)  . CompareCsMYB45-EGFP, 35S::CsMYB46-EGFP, and 35S::CsMYB105-EGFP in tobacco epidermal cells showed that the three target genes were all located in the nucleus , MeJA treatment alone (3 or 4 mM), and the combined treatment (16 °C cold stress and 3 mM MeJA), strains overexpressing CsMYB45, CsMYB46, and CsMYB105 showed higher growth rates compared with the empty vector control  leaf cells by bimolecular fluorescence complementation (BiFC) assays, indicating that CsMYB-CsJAZ complexes are conserved in tea plants . These results suggest that exogenous MeJA application can effectively enhance tea plant tolerance to cold stress. Under cold stress alone, REL increased remarkedly (T1), but there was no difference between CK and the T5 treatment when MeJA was applied together with cold stress. These results suggest that when tea plants were subjected to cold stress, the cell membrane structure was immediately damaged, resulting in increased permeability. However, exogenous MeJA application could effectively reduce REL under cold stress, assisting the tea plants’ return to their normal state. Anthocyanins are the most oxidized flavonoids and have the ability to neutralize or scavenge reactive oxygen species (ROS) production under stress, thereby increasing the antioxidant capacity of plants and serving as a protective mechanism under low temperatures . Here, wChlorophyll content increased immediately after cold stress alone (T1) but decreased after a long time of recovery from cold stress (T2). On the one hand, cold stress impairs the balance between chlorophyll synthesis and degradation, for example, by accelerating chlorophyll degradation and damaging the morphological structure of the chloroplast, thereby reducing chlorophyll content ,50. On tPlants have evolved with complex mechanisms to combat the oxidative damage induced by ROS, including the activity increase in antioxidant enzymes such as SOD, POD, and CAT, which are positively correlated with plant cold resistance . Here, wPPO gene family members StuPPO1, StuPPO2, StuPPO3, StuPPO6, StuPPO8, and StuPPO9 contain MeJA-responsive elements [PPO may be involved in the regulation of phenolic synthesis in response to MeJA, and low-temperature stress could inhibit the PPO activity.PPO plays a vital role in the development of tea buds, phenolic compounds synthesis, and the resistance of tea plants. It is particularly important for catalyzing the oxidation of polyphenols to quinones during tea processing . In thiselements . TherefoPAL and C4H are essential enzymes in the phenylpropanoid biosynthetic pathway. Trans-coumaroyl-CoA, a product of this pathway, was involved to generate anthocyanins and anthocyanidins through the flavonoid pathway, thereby participating in plant responses to abiotic stresses. PAL is considered to be the gateway for the phenylpropanoid pathway . Here, PCsMYB genes showed strong upregulation in response to these treatments. CsMYB45 expression increased significantly in response to exogenous MeJA alone and low-temperature stress alone. CsMYB46 and CsMYB105 expression levels were markedly higher under the individual and combined treatments than under control conditions. We, therefore, speculated that these three CsMYB TFs may play an essential role in the response to low-temperature stress via the JA signaling pathway. MYB proteins, particularly R2R3-MYB TFs, have been found to regulate the networks that control diverse plant processes, including responses to biotic and abiotic stresses, development, and primary and secondary metabolism . AlthougE. coli cells’ overexpressing genes with interest is one of the methods to validate gene function [CsMYB45, CsMYB46, and CsMYB105 enhanced the tolerance of E. coli to low-temperature stress. Strains overexpressing CsMYBs under cold stress alone (16 °C), MeJA treatment alone, or the combined treatment showed better growth rates compared with the empty vector and normal conditions (25 °C). We also observed that strains overexpressing CsMYB45, CsMYB46, and CsMYB105 showed enhanced cold tolerance when exogenous MeJA was added. These results prove that CsMYB45, CsMYB46, and CsMYB105 play essential roles in the cold stress response of E. coli via the jasmonic acid signal transduction pathway.CsMYB45, CsMYB46, and CsMYB105 were localized in the nucleus of tobacco epidermal cells, which was consistent with previous findings ,66. Relefunction ,68. HereArabidopsis MYB proteins interacted with several JAZ proteins and formed dimers [Arabidopsis [MYB family genes have been shown to regulate the jasmonic acid signal transduction pathway by interacting with the inhibitor JAZ in the SCFCOI1-JAZ ubiquitin proteasome degradation pathway. They participate in a various of jasmonic acid related processes, including JA-induced anthocyanin synthesis and the regulation of plant cold resistance. A previous study revealed that d dimers . For exad dimers . A repord dimers . Furtherbidopsis . Accordibidopsis . Therefo−2 s−2 and 75% relative humidity for one week. For the cold stress treatments, tea plants were exposed to 4 °C for 4 days. For exogenous MeJA treatments, tea plants were sprayed with 100 μM MeJA on 4 consecutive days. These treatments were combined to produce six experimental treatment regimens , where the photoperiod was 8 h light (25 °C)/16 h dark (20 °C) with a light intensity of 200 μmol mregimens . Three biological replicates, consisting of one bud and two leaves in each, were collected from the six treatments and the control. All samples were immediately frozen in liquid nitrogen and stored at −80 °C for subsequent experiments. Total anthocyanin content was measured according to the Proctor  method. Chlorophyll contents were determined using an ultraviolet spectrophotometer, following the method described by Lichtenthaler . Each teAll analyses were repeated three times.The relative ion leakage rate was measured by referring to Cai et al. . Leaf diProline, MDA, and soluble sugar contents were measured as described by Cai et al. . POD (Pehttp://tpia.teaplant.org/index.html (accessed on 10 May 2019)), 127 MYB TF family members related to MeJA and cold stress were identified in the tea plant cultivar ‘Shuchazao’. Through heat map analysis of the expression levels of these 127 MYB genes, in response to low temperature and MeJA, 16 MYB genes with high expression under low temperature and MeJA treatment were identified, and their gene sequences and the expression data were obtained from the Tea Plant Genome Database (http://tpia.teaplant.org/download.html (accessed on 10 May 2019)). Based on the Tea Plant Information Archive database . Csβ-actin gene was used as an internal control. The primer pairs used for qRT-PCR were listed in CsMYB genes were calculated using the 2−ΔΔCt method [CsMYB genes were identified to show significantly different expression under the cold and MeJA treatments, which were used in the following experiments.Total RNA was isolated from the samples using the RNA Quick Isolation kit , and reverse transcription was performed with One-Step gDNA Removal and cDNA Synthesis SuperMix . Expression analysis of the sixteen t method . Based oCsMYB45, CsMYB46, and CsMYB105 ORF sequence were amplified from the entry vector pDONR201 construct using the pDONR-attb-CsMYBs -F/R primer pair  to generate fusion vectors 35S::CsMYB45-EGFP, 35S::CsMYB46-EGFP, and 35S::CsMYB105-EGFP. The recombinant plasmid  and the empty vector 35S::EGFP were transformed into cells of Agrobacterium tumefaciens strain GV3101. Subsequently, we co-transformed GV3101 containing the recombinant plasmids or empty vector with the nuclear marker P19-mCherry for transient transformation in tobacco leaves (Nicotiana benthamiana). Plants were incubated in the dark for 48 h after infection, and leaves’ GFP fluorescence signal was monitored with Zeiss LSM 800 confocal microscope . The mer pair  harborinCsMYB45, CsMYB46, and CsMYB105 were digested with EcoRI, and the resulting gene fragments were cloned into the expression vector pGEX-4T-1 (Amersham Biosciences) using Cloning Kit C112   and the empty vector pGEX-4T-1 were transformed into Escherichia coli ROSETTA cells and cultured in LB medium with 100 mg/L ampicillin at 37 °C until the optical density at 600 nm (OD600) reached 1.0. The transformants harboring and empty strain were added to LB medium (100 mg/L ampicillin), containing different concentrations of MeJA  at a ratio of 1:1000. Each mixture was then divided into two parts: one was placed in a constant 37 °C temperature incubator with shaking at 200 rpm, and the OD600 value was determined with an ultraviolet spectrophotometer after different incubation times .The open reading frames (ORFs) of , China) . The recE. coli, so the incubation times was prolonged. The OD600 value was measured with an ultraviolet spectrophotometer at different incubation times . Strains exposed to different treatments with different culture durations were then collected and inoculated onto LB basal plates containing 100 g/L ampicillin. All plates were cultured at 37 °C overnight for 12 h, and the growth of E. coli was observed and photographed.The other part was exposed to low temperature (16 °C) at an initial OD600 value for the four strains set to 0.2 with shaking at 200 rpm. Cold stress could inhibit the growth rate of BamHI, resulting in the plasmids pGBKT7-CsMYB45, pGBKT7-CsMYB46, and pGBKT7-CsMYB105. pCL1 (positive control), and pGBKT7 (negative control) plasmids were introduced into Saccharomyces cerevisiae strain Y2H Gold (Clontech), in accordance with the protocol of the manufacturer , whereas those harboring pCL1 were selected on SD/-Leu medium. As a positive control, Y2H cells harboring pCL grew well on SD/-His-Ade medium, but the negative control Y2H cells harboring pGBKT7 did not grow on SD/-His-Ade medium. The transcriptional activation of CsMYB45, CsMYB46, and CsMYB105 was determined in the yeast system. The ORFs of CsMYB45, CsMYB46, and CsMYB105 were constructed in the pGBKT7 vector using facturer . The traCsMYB45, pGBKT7-CsMYB46, and pGBKT7-CsMYB105, and a verification experiment was performed using Clontech system . The positive control plasmids were pGADT7-T and pGBKT7-53, and the negative control plasmids were pGADT7-T and pGBKT7-lam. A construct of the ORF of CsJAZ3, CsJAZ10, and CsJAZ11 in the pGADT7 vector was generated using BamHI, resulting in the plasmids pGADT7-JAZ3, pGADT7-JAZ10, and pGADT7-JAZ11, with the CsJAZ3, CsJAZ10 and CsJAZ11-AD-F/R primers . The primers used for vector construction are shown in Bimolecular fluorescence complementation (BiFC) assays were performed in tobacco epidermis cells. The ORFs of p < 0.05).All data in this study were analyzed using Excel (version 2018) and IBM SPSS Statistics (version 26.0), and the results were presented as the mean ± standard deviation (SD). The data were analyzed in Excel, and the visualizations were analyzed with GraphPad Prism software (version 8.0). Significant differences between the experimental treatments were tested by SPSS (version 26.0) using one-way ANOVA, and Duncan’s multiple range test was used as indicated by different letters (CsMYB genes showed high relative expression levels in response to MeJA or cold-stress treatments. Three CsMYB genes were strongly induced under a combination of MeJA and cold-stress treatment. Subcellular localization assays demonstrated that CsMYB45, CsMYB46, and CsMYB105 fused proteins were localized in the cell nucleus. Exogenous MeJA treatment enhanced the overexpression of CsMYB45, CsMYB46, and CsMYB105 in E. coli and improved the growth and survival rates of recombinant cells under cold stress. Yeast two-hybrid and bimolecular fluorescence complementation experiments confirmed that CsMYB46 and CsMYB105 interacted with CsJAZ3, CsJAZ10, and CsJAZ11 in the nucleus. These findings extend our understanding of how MYB TFs participate in the regulation of cold tolerance via the jasmonic acid pathway and provide a theoretical foundation for future functional studies.In summary, physiological and biochemical assays showed that exogenous MeJA application could effectively promote ROS scavenging in the tea plant under cold stress, maintain the stability of the cell membrane, and further relieve the damage caused by cold stress, thereby enhancing the cold tolerance of tea plants. Sixteen of 127


Transcription factors directly regulate gene expression by recognizing and binding to specific DNA sequences, involving the dynamic alterations of chromatin structure and the formation of a complex with different kinds of cofactors, like DNA/histone modifying-enzymes, chromatin remodeling factors, and cell cycle factors. Despite the significance of transcription factors, it remains unclear to determine how these cofactors are regulated to cooperate with transcription factors, especially DNA/histone modifying-enzymes. It has been known that DNA/histone modifying-enzymes are regulated by post-translational modifications. And the most common and important modification is phosphorylation. Even though various DNA/histone modifying-enzymes have been classified and partly explained how phosphorylated sites of these enzymes function characteristically in recent studies. It still needs to find out the relationship between phosphorylation of these enzymes and the diseases-associated transcriptional regulation. Here this review describes how phosphorylation affects the transcription activity of these enzymes and other functions, including protein stability, subcellular localization, binding to chromatin, and interaction with other proteins. Protein phosphorylation is crucial for various cellular processes, including cell growth, DNA damage, metabolism, inflammation. By definition, various protein kinases phosphorylate serine (Ser), threonine, and tyrosine of targeted proteins. Phosphorylation is one of the most common post-translational modifications (PTMs). It generally alters the structural conformation and interaction of proteins, by which it directly influences protein stability, cellular localization, protein/DNA binding, and enzymatic activity .www.phosphosite.org) and the Kinexus PhosphoNET (www.phosphonet.ca). Among these reported proteins, there are some transcriptional factors (TFs) and the cofactors. It has been clearly defined how TFs and the cofactors organize and regulate gene transcription. In general, TFs firstly occupy DNA elements in a sequence-specific manner, and then recruit the RNA polymerases to the gene’s promoter region, which simultaneously involve chromatin remodeling complexes and histone (de)acetyltransferases for promoter accessibility . Ly. Ly54]. KMT1A, known as SUV39H1, is phosphorylated at residues Tyr297 (mouse Tyr303 and flies Tyr308) by receptor-type tyrosine kinase ERBB4, which enhances the tri-methylation activity of histone H3K9 . And theProtein arginine methyltransferases 1 (PRMTs) are a kind of enzymes, which are mainly responsible for histone arginine methylation in cells and regulate the cell cycle and cell proliferation by remodeling chromatin status. Phosphorylation of PRMTs is essential for its enzymatic activity and protein stability. It is reported that PRMT1 is phosphorylated at Ser297 in normal liver cells, while it is dephosphorylated by PP2A at this site in response to alcohol and other oxidative stresses . It suggHistone lysine demethylases (KDMs), in contrast to KMTs, function to remove methyl groups of methylated histone proteins. The alters on histone methylation by KDMs regulate gene expression in the processes of development and tumor growth . And KDMHistone acetyltransferases (HATs) are major players in epigenetically modulating gene transcription via acetylation on histones Fig. . They reUntil now, P300 is the most studied protein about its functions influenced by phosphorylation. Among these phosphorylated sites we have summarized, phosphorylation of Ser1834 by AKT, Ser2271, Ser2279, Ser2291, and Ser2315 by mTOR, and Ser2279, Ser2315, and Ser2366 by extracellular signal-regulated kinase 2 (ERK2), significantly enhances P300 acetylation activity –107. P30AKT also phosphorylates the acetyltransferase p300/CBP-associated factor (PCAF) and increases its acetylation on high-mobility group AT-hook 2 (HMGA2) at lysine 26 (K26) for esophageal squamous cell carcinoma growth . The pho+ as a cofactor for the enzyme activity. In addition, other transcription factors, such as TCF1 and LEF1, is discovered recently to own the ability of deacetylating H3K9ac and H3K27ac [Histone acetylation and deacetylation are dynamic processes dependent on cell states. Histone acetylation and deacetylation are performed by KAT family proteins and histone deacetylases (HDACs). There are four classes of HDACs based on their homologous protein sequences: the class I RPD3-like proteins including HDAC1, HDAC2, HDAC3, and HDAC8; class II HDA1-like proteins are HDAC4, HDAC5, HDAC6, HDAC7, HDAC9, and HDAC10; class III sirt2-like proteins containing SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6, and SIRT7; class IV protein is HDAC11. Many HDACs, which belong to class I, II, IV, require a zinc ion to deacetylate acetylated lysine, but for the class III HDACs, the proteins require NAD H3K27ac . But herIn class I HDACs, HDAC1 is phosphorylated by various protein kinases and the specific sites directly influence HDAC1 subcellular localization, enzymatic activity and protein stability Table . One of Phosphorylation by various serine/threonine kinases alters the subcellular localization of HDACs. HDAC4, as one of class II HDACs, is commonly verified to be phosphorylated at Ser246, Ser467, and Ser632 by calmodulin kinase II (CaMKII), which lead to nuclear export of HADC4 to the cytoplasm –150. Ano+) as a cofactor. It is originally discovered in yeast and characterized to deacetylate histones for transcription repression [SIRT (1–7) belongs to the class III HDACs with nicotine adenine dinucleotide (NADpression . Structupression . P53 acepression . The phopression –189. SIRpression –192. AndIt is worth noting that several enzymes, including EZH2, P300, KAT7, KAT13A, and almost of HDACs, own a relatively large number of functional phosphorylation sites in the summarized tables. EZH2 is comprised of SANT domain, CXC domain, and catalytic SET domain. The phosphorylated sites in the N-terminal domain of EZH2 by various protein kinases not only inhibits its methylation activity, but also promotes its ubiquitination for degradation. Only one site, Thr350, can be phosphorylated and activates enzymatic activity of EZH2. And phosphorylation of Ser646 in the region of SET domain of EZH2 promotes its degradation in malignant lymphoma . Even itIn this review, we specifically discuss how phosphorylation regulates two kinds of transcription cofactors, including DNA methylation/demethylation-related enzymes and histone-modifying enzymes (the model in Fig. Since the discovery of histone PTMs, it has been evidenced to be dynamic and reversible . DNA and


Coronavirus disease 2019 (COVID-19) has been associated with acute kidney injury in kidney transplant recipients by several mechanisms. The authors report a case of acute kidney allograft dysfunction in a 48-year-old patient who presented in the emergency room with anasarca and nephrotic syndrome close after mild COVID-19 and no other clinical condition. Histopathology of the allograft biopsy revealed two distinct and simultaneous kidney lesions, collapsing glomerulopathy and thrombotic microangiopathy. Renal function persistently deteriorated, and definitive dialysis was initiated. After excluding other plausible causes for the findings, this case strengthens the hypothesis that the kidney allograft is also a target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).  At admission, physical examination was unremarkable other than anasarca, with peripheral oxygen saturation of 95% and clear pulmonary auscultation. Blood analysis revealed white blood cells count (WBC) of 10.7 × 10⁹/L, hemoglobin of 10.3 g/dl, platelets of 247,000/m³ , C-reactive protein (CRP) of 0.51 mg/dL (RR: 0-0.11 mg/dL), lactate dehydrogenase (LDH) of 260 UI/L (RR: 140-270 UI/L), creatinine (Cr) of 6.3 mg/dL, albumin of 2.9 g/dl, tacrolimus trough blood concentration of 8 ng/mL, C3 of 83 mg/dl (RR: 87-200 mg/dl), C4 of 32 mg/dl (RR: 19-52 mg/dl). The urinary protein-creatinine ratio was 15.6. Polymerase chain reaction (PCR) assay for SARS-CoV-2 from nasopharyngeal swab resulted positive (cycle threshold of 24.18). Chest computed tomography (CT) showed scarce small nodules, some with a ground-glass halo, and other focal opacities, some ground-glass, also scattered throughout the lung lobes, predominantly in the right upper lobe.A percutaneous kidney biopsy was performed two days after admission revealing collapsing glomerulopathy in two of the nine glomeruli samples with the global collapse of the capillary tuft accompanied by pronounced podocyte hyperplasia and hypertrophy and swelling of epithelial cells Figure . AdditioFrom the respiratory point of view, the patient had a benign evolution, with no need for oxygen therapy during her hospitalization. However, facing the severity of kidney dysfunction and the histological findings, supportive treatment was instituted with dialysis, volemia control, and antihypertensive treatment. No specific measure was applied, and the patient maintained surveillance for infectious and late COVID-19 complications. After 21 days of hospitalization, the patient was discharged, after resolution of edema, constitutional and respiratory symptoms, under chronic hemodialysis and was reincluded in the kidney transplant waiting list. In the general population, it is postulated that SARS-CoV-2 can cause kidney injury by diverse mechanisms, including interaction with its cellular receptor ACE-2, virus-induced systemic cytokine storm, prothrombotic effects and direct viral invasion -3,11,12.Among kidney transplant recipients, COVID-19 has been demonstrated to directly result in high morbidity and mortality, with an attributed fatality rate ranging from 20% to 30% in the pre-omicron era -18. TherIn the present report, the kidney allograft biopsy revealed coexistent collapsing glomerulopathy and thrombotic microangiopathy (TMA). In a series of 17 kidney biopsies (14 of native kidney and three of transplant kidney) performed in COVID-19 patients from seven large centers in the United States, two of the native kidney biopsies also revealed both lesions, whose patients presented with nephrotic syndrome and severe AKI, progressing to kidney failure and dialysis . In anotIt is possible that the podocytopathy and microcirculation thrombotic lesions resulted from two distinct mechanisms, as the lesions appeared in different glomeruli. On the one hand, the virus may have promoted direct or indirect podocyte injury through ACE-2 receptor expressed by podocytes, cytokine-mediated injury, or enhanced type 1 interferon expression, this last resembling HIV nephropathy. On the other hand, the presence of microthrombi in glomerular tufts and mesangiolysis indicated endothelial injury, possibly from direct viral toxicity to the endothelium or through uncontrolled activation of the alternative complement pathway by the infection, acting as a second hit, unmasking an underlying genetic defect, which unfortunately was not evaluated in this case.The authors describe a clinical case where two distinct lesions, rarely observed in kidney transplant recipients with mild COVID-19, occurred simultaneously with a poor allograft outcome. Although causality between viral infection and subsequent glomerulopathy cannot be proven, this report warns that not all renal dysfunctions following infection are due solely to tubular compartment injury. In addition, it reflects that unfavorable transplant outcomes are possible even in a mild COVID-19 setting.


Anthracyclines (ANTs) are a class of anticancer drugs widely used in oncology. However, the clinical application of ANTs is limited by their cardiotoxicity. The mechanisms underlying ANTs-induced cardiotoxicity (AIC) are complicated and involve oxidative stress, inflammation, topoisomerase 2β inhibition, pyroptosis, immunometabolism, autophagy, apoptosis, ferroptosis, etc. Ferroptosis is a new form of regulated cell death (RCD) proposed in 2012, characterized by iron-dependent accumulation of reactive oxygen species (ROS) and lipid peroxidation. An increasing number of studies have found that ferroptosis plays a vital role in the development of AIC. Therefore, we aimed to elaborate on ferroptosis in AIC, especially by doxorubicin (DOX). We first summarize the mechanisms of ferroptosis in terms of oxidation and anti-oxidation systems. Then, we discuss the mechanisms related to ferroptosis caused by DOX, particularly from the perspective of iron metabolism of cardiomyocytes. We also present our research on the prevention and treatment of AIC based on ferroptosis. Finally, we enumerate our views on the development of drugs targeting ferroptosis in this emerging field. With the advancements in medical technology, while the survival time of cancer patients has been prolonged, cardiovascular toxicity has become one of the most severe complications of cancer treatment , 2. StudFerroptosis is a new form of regulated cell death (RCD) different from apoptosis, necrosis, necroptosis, pyroptosis, and autophagy. It is characterized by iron overload and reactive oxygen species (ROS) accumulation, resulting in lipid peroxidation of cell membranes , 12. A fFerroptosis is an iron-dependent lipid peroxidation induced novel RCD, caused by redox imbalances between the oxidant and antioxidant systems. Antioxidant systems include the Cyst(e)ine-GSH-glutathione peroxidase 4 (GPX4) pathway, the ferroptosis suppressor protein 1 (FSP1)-coenzyme Q10 (CoQ10)-nicotinamide adenine dinucleotide phosphate (NADPH) pathway, the GTP cyclohydrolase-1 (GCH1)-tetrahydrobiopterin (BH4) pathway, etc. , 16. Int3+) by binding to transferrin (Tf). Fe3+ enters the endosome through membrane protein transferrin receptor 1 (TfR1). Then, Fe3+ is reduced to ferrous iron (Fe2+) by the iron reductase activity of the six-transmembrane epithelial antigen of the prostate 3. The divalent metal transporter 1  releases Fe2+ from the endosome into the cytoplasm. While part of the Fe2+ in the cytoplasm is stored as ferritin, part is oxidized to Fe3+ and transported outside the cell by the membrane protein iron transporter ferroportin , and the rest is stored in the labile iron pool (LIP) of the cytoplasm or mitochondria , evidenced by increased cell viability and decreased lipid ROS production in HT-1080 cells. In contrast, the erastin-induced ferroptosis was triggered by incubation with three different exogenous iron supplements . In intechondria . The irochondria . Moreovechondria . Therefochondria .2+ in LIP, which also exacerbates ferroptosis  –27 and Froptosis , 41.2+ in LIP can spontaneously undergo redox reactions to produce ROS, including both Fenton and Harber-Weiss reactions. The chemical equations are as follows (Fe follows :2O2 and active oxygen (O2•–) (•) combines with polyunsaturated fatty acids (PUFA) on the biomembrane to generate the phospholipid radical (PL•). Secondly, PL• reacts with O2 generating a phospholipid peroxyl radical (PLOO•). Thirdly, PLOO• reacts with PUFA to generate phospholipid hydroperoxide (PLOOH) and PL•, which can react again with O2, forming a vicious circle. The other is the enzymatic way, that is, PUFA generates PLOOH under the action of LOXs. However, the detailed mechanism of PLOOH resulting in ferroptotic lipid peroxidative cell death remains obscure. Continued oxidation and consumption of PUFA may alter the structure of lipid pores, ultimately leading to compromised membrane integrity. In addition, PLOOH may be decomposed into active toxic aldehydes, such as 4-hydroxy-2-nonenal or malondialdehyde (MDA), causing cytotoxic effects -OOH, PE(38:4)-OOH, and PE(40:4)-OOH (2O) (n) (+) (n > 28000) cluster ion beam to visualize them at the single-cell and subcellular levels (The electron transport system of mitochondria is the primary source of Hn (O2•–) . ROS, ge effects . The hal effects . Besides0:4)-OOH . Sparverr levels . The fer–, a heterodimeric 12-pass transmembrane cystine–glutamate anti-porter, consists of a xCT light chain  that mediates cystine transport specificity, and a 4F2 heavy chain  (The cyst(e)ine-GSH-GPX4 pathway is considered the canonical pathway for restricting ferroptosis. System Xc SLC3A2) , plays a SLC3A2) . GPX4 is SLC3A2) . Cardiac SLC3A2) . Surpris SLC3A2) . In addi SLC3A2) . GPX4 is SLC3A2) . Seleniu SLC3A2) .in vitro and enhanced tumor growth in vivo  in M1 macrophages has been confirmed to inhibit the effect of NO (•) on epithelial cells by inhibiting phospholipid peroxidation, especially the generation of 15-HpETE-PE signal that promotes ferroptosis. It is an intercellular mechanism that distantly prevents the ferroptosis of epithelial cells stimulated by Pseudomonas aeruginosa -like 2 signaling is implicated in many molecular aspects of ferroptosis, including glutathione homeostasis, mitochondrial function, and lipid metabolism , 62. Thein vitro . In immuin vitro .2•–, OH•, OH–, H2O2, PL•, PLOO•, PLOOH, ROS, etc. play important roles in the occurrence and development of ferroptosis. Superoxide dismutase (SOD) and superoxide reductases can reduce O2•– to H2O2. Catalase catalyzes H2O2 to water and O2. Water-soluble ascorbic acid (vitamin C), lipid-soluble vitamin E or α-tocopherol (α-TOH), and lipoic acid can reduce lipid hydroperoxide production and peroxyl radicals. Besides, ascorbic acid increases the vitamin E content by reducing vitamin E semiquinone  mice and necroptosis-defective (Mlkl–/–) mice, intraperitoneal injections of Fer-1 (20 mg/kg) followed by DOX in normal mice improved their survival rate remarkably  to become semiquinones, which was then accompanied by the ROS production such as Oneration . In addimore ROS . DOX canmore ROS , 77, 78.pression .We know that ferroptosis is an iron-dependent lipid peroxidation process, and iron is essential in both the occurrence and development of this process. It is generally believed that excessive iron can aggravate DIC. More than 20 years ago, research indicated that iron overload aggravated DIC . DOX red–/– mice. Mutations in the HFE gene led to iron overload in cardiomyocytes, which increased the susceptibility of cardiomyocytes to ferroptosis and exacerbated DIC  cells was reversed  and storage (ferritin). As for TfR1, most studies believe that DOX could elevate its expression –89. A streversed . The mecleviated . As for leviated . After bleviated . Similarleviated . In addileviated . Therefo2O2 activated IRP1, leading to the upregulation of TfR1 and cellular iron accumulation, which was considered an important molecular mechanism in DIC  and certain products of DOX metabolism, converted cytoplasmic aconitase to the cluster-free IRP1 by removing iron from its catalytic [Fe-S] clusters. This eventually produced a null protein, which could not adapt the levels of TfR1 and ferritin, and IRP2 was inactivated only by DOX related ROS . Some scm in DIC . One stum in DIC . Howeverm in DIC . Howevermyocytes . Gianframyocytes . Furthermyocytes . Besidesmyocytes . Anyway,myocytes .2+) in the DOX-induced primary neonatal rat ventricular myocytes and C57BL/6 J mice cardiotoxicity models, and this influence can be mitigated by PRMT4 knockout , Hemin (an HO-1 activator), DOX has been proven to increase HO-1 by affecting Nrf2 and accelerating the degradation of heme, leading to an increase in non-heme iron and myocardial ferroptosis. An increase in intestinal iron absorption did not accompany this increase of iron content. In this study, DOX was confirmed to be able to upregulate hepatic Hamp1 mRNA to increase hepcidin and reduce FPN degradation , activates the transcription of a series of downstream genes, and exerts physiological functions . Notablyknockout . Howeverroptosis , 104. Thradation . In addiradation .2, some escape from the ETC and react directly with O2 to form O2•–, a precursor to many other ROS such as OH• and H2O2  of DOX, as manifested by higher mortality, more morphological changes , more severe lipid peroxidation, and worse cardiac function (ATP and BNP)  . In micein vitro , 117. Thin vitro .On the contrary, another study showed that DOX affected more cytosolic than mitochondrial iron metabolism in murine hearts and human HeLa cells, as manifested by alterations in proteins associated with cytoplasmic iron transport proteins . In contrast, mitochondrial iron-related proteins  appear to be unaffected . In addi3+ to form the DOX-Fe3+ complex , Fer-1 attenuates lipid peroxidation by decreasing erastin-induced accumulation of cytosolic and lipid ROS, consequently inhibiting ferroptosis . This is+ in LIP .3+ center to the inactive Fe2+, thereby inhibiting lipid peroxidation  can also improve cell survival rate. In HEK-293 cells, the mechanism by which Fer-1, liproxstatin-1, and α-TOH inhibit lipid hydroperoxides and bring about ferroptosis was demonstrated to be achieved by capturing chain-carrying peroxyl radicals, rather than inhibiting LOXs or restoring GSH levels –150. Howxidation . Other axidation . Anotherin vitro , 153. Otin vitro .Although many experiments have demonstrated that ferroptosis could be attenuated by inhibiting lipid peroxidation and iron accumulation, studies using DOX-induced cardiomyopathy models are scarce, and the efficiency and safety of these drugs against ferroptosis are still questionable .According to recent research, DIC was also associated with insulin signaling imbalance and cardiac insulin resistance , 155. MeD-glucose, 5-aminoimidazole-4-carboxamide ribonucleotide, and A769662) were demonstrated to activate AMPK. This further inhibited acetyl-CoA carboxylase, and in turn palmitic acid (C16:0), thereby reducing the synthesis of PUFA, all of which suppressed ferroptosis , the energy-stress inducers  have a great potential in predicting patient susceptibility to DIC. Furthermore, the human-derived DOX cardiomyocyte injury model established by hiPSC-CMs overcomes the species differences of current research models and can be accurately used to understand the mechanism of ferroptosis in DIC .In summary, ferroptosis has been demonstrated by several studies to mediate the occurrence of AIC. In fact, DOX can increase the ROS content and affect iron metabolism in cardiomyocytes by acting on iron homeostasis regulatory proteins, such as, IREs/IRPs, and Nrf2/HO-1, resulting in the accumulation of lipid peroxides, thereby inducing ferroptosis. Mitochondria are the main organelle for inducing ferroptosis in cardiomyocytes. With further research, inhibition of ferroptosis could act as an effective strategy in both prevention and treatment of AIC. This would require screening for potential drugs that inhibit ferroptosis forcefully in cardiomyocytes or developing novel ferroptosis inhibitors and will surely benefit cancer patients with heart diseases as well as patients with high cardiovascular risk stratification.YX and SS designed this study. GZ wrote the first draft of this manuscript and created the figures. CY and XS searched the literature. JZ and XY participated in discussions and improved pictures related to the manuscript. PG, GV, GL, NA, CL, WS, HC, and MW critically revised and approved the final manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Plastic waste pollution, including non-biodegradable landfills, leaching of toxic chemicals into soil and waterways, and emission of toxic gases into the atmosphere, is significantly affecting our environment. Conventional plastic waste recycling approaches generally produce lower value materials compared to the original plastic or recover inefficient heat energy. Lately, upcycling or the valorization approach has emerged as a sustainable solution to transform plastic waste into value-added products. In this review, we present an overview of recent advancements in plastic waste upcycling, such as vitrimerization, nanocomposite fabrication, additive manufacturing, catalytic transformation, and industrial biotechnology, envisaged with technical challenges, future developments, and new circular economy opportunities. ConversOver the last decade, upcycling or creative reuse has emerged as a promising alternative to recycling plastic waste. In the upcycling approach, the plastic waste is reused in such a way as to create a product of higher quality or value than the original, which provides a technical solution for smarter waste management, new product development, and the circular economy. State-of-the-art upcycling concepts  involve physical , chemical , and biological  methods to convert plastic waste into polymers , molecules , and materials  . HoweverIn recent years, vitrimerization has emerged as a promising novel approach to reprocess and recycle intractable waste via dynamic chemistry, which involves dynamic covalent bonds, a special type of covalent bond. Dynamic bonds can be dissociative or associative under external stimuli. Materials synthesized with dynamic covalent bond crosslinks are commonly referred to as covalent adaptive networks (CANs) . Vitrimeb) and PE packaging waste (PEp) into re-processable high-performance vitrimers  using melt extrusion processing. The vitrimers were synthesized by first grafting the plastics with MA, followed by crosslinking with bisphenol A diglycidyl ether (DGEBA) using zinc acetylacetonate hydrate (Zn(acac)2) as the transesterification catalyst  andIn nanocomposite fabrication, advanced functional materials with tailored properties are developed by incorporation of functional nanofillers into the plastic waste matrix at desired concentrations. The cost, quality, and application of these nanocomposites depend on the type of plastic waste, property, and quantity of the incorporated nanomaterial, as well as the processing route used for composite fabrication. The fabricated composites can be used as such (this section) or can be thermochemically transformed into carbonaceous composites see . A summa2) and titanium dioxide (TiO2) NPs in liquid paraffin, followed by extrusion, granulation, and thermal compression molding. The fabricated composite membrane exhibited tensile strength of 8.4 MPa and a UV protection factor of 1500+ [−10 S/cm) nanocomposite. This work was further extended to fabricate nanocomposites using multilayer plastic package waste comprising 80% LDPE and 20% polyamide, where surface-oxidized Al nanoflakes were powder mixed at different ratios and compression molded into sheets exhibiting thermal conductivity in the range of 1.4–4.8 W/mK and high electrical insulation (conductivity of 10−13 S/cm) [Yasin et al.  reportedof 1500+ . Wang anof 1500+  reported13 S/cm) .2) NPs using a thermally induced phase separation (TIPS) method, which exhibited a photodegradation efficiency of 98.2% for rhodamine B dye under UV irradiation and can be potentially applied for water treatment and filtration applications. Recently, Uddin et al. [2 NPs and Al microparticles, which exhibited a water contact angle of 157°. The fabricated membranes were demonstrated for fog-harvesting capability with daily water productivity of >1.35 L/m2. In addition, plastic waste-based transformed nanocomposites, where the plastic is converted into carbonaceous material in the final composite product, have also been reported. For example, Mir et al. [2C) nanocomposites using plastic waste (pipette tips) and molybdenum trioxide via an in-situ carburization route. The obtained Mo2C nanocomposite has potential for hydrogen production and energy storage applications. However, such transformations are considered as chemical upcycling rather than nanocomposite formulations.Conversely, Assis et al.  fabricatn et al.  fabricatr et al.  reportedAdditive manufacturing, or three-dimensional (3D) printing, is a constructive technique for building 3D objects from digital models. The 3D printing of plastics has gained increasing research attention in recent years due to its remarkable potential for fabricating complex structures, customizing the product at will, and reduced lead time and waste, which are advantages in comparison to many traditional manufacturing processes commonly used in industries . Fused fIncorporation of biochar has been recognized to improve mechanical, thermal, and electrical properties of polymer composites . Idrees Conversely, Stoof et al.  fabricatPlastic waste can be used as an important feedstock material for the preparation of value-added platform chemicals. Conventional approaches used for chemical recycling of plastic waste include pyrolysis , gasification , and solvolysis  . However2) can be potentially achieved using transition 3d-metals  containing nanocatalysts. Cai et al. [2O3) nanocatalyst, and they reported that more nanotubes and pure carbon nanotubes (CNTs) can be produced from polyolefin, whereas more amorphous carbon and H2 can be produced from PS. However, coke deposition and metal sintering at higher temperatures affect the stability of the catalyst, particularly for Ni, which can be resolved by using bimetallic catalysts [2 [2O3-supported Ni-Cu bimetallic nanocatalyst with a Ni:Cu ratio of 4:1. The group also reported the production of nanostructured carbon materials from LDPE waste using magnesium oxide-supported iron–molybdenum (Fe-Mo/MgO) bimetallic nanocatalysts. An intermediate loading of Fe and Mo produced mainly CNTs, accompanied with CNFs and graphene nanosheets (GNSs) as hybrid materials, whereas a higher Fe or Mo loading promoted the formation of both CNTs and CNFs [Raw materials can be produced via catalytic pyrolysis of plastic waste, which is performed in presence of a Lewis acid catalyst or solid acid catalyst, where mostly aromatic products or gases are produced by catalyzed carbocation, isomerization, aromatization, or crackling . For exai et al.  performeatalysts . Consequlysts [2 . For inslysts [2  demonstrand CNFs . Furtherand CNFs .2, methane (CH4), and carbon monoxide (CO), are produced by catalyzed pyrolysis, crackling, and reforming by oxygen [2-rich syngas as it exhibits high ability for the coordination and activation of C–H and C–C bonds, which suppresses coke deposition [plastic at 850 °C. Similarly, catalytic steam reforming of HDPE waste using the Ni/ZSM-5 nanocatalyst has been reported to produced 100.72 mmol/gplastic of syngas at 850 °C [2–ZrO2 shell for H2-rich syngas (66.81 mol% of H2 at 800 °C) production from HDPE waste by gasification. In a separate study, Zhang et al. [plastic) by gasification of HDPE waste. The gas products largely consist of H2 (33.66 mmol/gplastic); a considerable amount of CO, CH4, and CO2; and trace amounts of the C2+ component. Lately, the Al2O3-supported Ni nanocatalyst has also been reported to enhance the production of syngas by gasification of polyolefin waste. For instance, Arregi et al. [2O3 nanocatalyst for steam reforming/gasification of PP waste and reported a space time of 16.7 gcatalyst min gplastic–1 was required for full conversion and high H2 production. Moreover, when metal oxides, such as lanthanum oxide (La2O3) and cerium oxide (CeO2), were used as the second promotor, a significant increase in H2 production was observed. In addition, microwave, plasma, and supercritical water have also been reported to enhance nanocatalyzed gasification [Catalytic gasification is another route to upcycling of plastic waste, which can be performed in the presence of a solid acid-supported metal catalyst, where combustible gases with high calorific value, such as Hy oxygen . The Ni-position . Asadi eposition  investigt 850 °C . On the t 850 °C  designedg et al.  synthesii et al.  investigfication .2-rich syngas, solvolysis produces monomers by depolymerization of plastic waste in the presence of solvent, which is largely used as feedstock for polymer resynthesis. Moreover, solvolysis is largely targeted for depolymerization of hydrolysable plastics like PET and PU, and it faces challenges like longer completion time, smaller batch size, and difficulty in separating feedstock impurities including the catalyst used. Therefore, solvolysis is commonly considered for plastic waste recycling and combined with other techniques for upcycling [Unlike nanocatalyzed pyrolysis and gasification, which produce value-added products like CNTs and Hpcycling .2 to produce value-added hydrocarbons like alkanes, cycloalkanes, alkenes, alkynes, and aromatics [2)-supported Pt catalyst (Pt/ZrO2) and studied the effect of different Pt loading on hydrogenolysis of LDPE plastic waste into liquid fuels, where an increase in activity and selectivity for catalytic hydrocracking was observed with the increase in Pt loading. Jumah et al. [2) of LDPE waste for high yield (>95% conversion) production of C4−C6 alkanes using a Pt-impregnated USY zeolite catalyst (Pt/USY). In a separate study, the Pt/SrTiO3 catalyst fabricated by depositing (by atomic layer deposition) Pt-NPs on hydrothermally synthesized strontium titanate (SrTiO3) perovskite nanocuboids hydrogenolyzed (at 300 °C under 170 psi H2) PE waste to lubricants and waxes, characterized by a narrow distribution of oligomeric chains [2)-based ordered Pt/SiO2/mSiO2 catalyst  and demonstrated its potential for hydrogenolysis of HDPE into a narrow distribution of diesel and lubricant-range alkanes. A single pot catalyst strategy to branched products via adhesive isomerization and hydrocracking of PE (at 250 °C under 30 bar H2) was also realized. The method used a Pt-impregnated tungstated zirconia (WZrO2) catalyst (Pt/WZrO2) to produce alkanes, where an increase in the metal-to-acid site molar ratio shifted the extractable product selectivity (C1–C35) to heavier hydrocarbons and enhanced branching in the residual polymer [3/ZrO2) along with HY zeolite catalyst was reported by Liu et al. [2) with a yield of up to 85% involved tandem catalysis with initial activation of the polyolefins over Pt, followed by polymer cracking over the acid sites of WO3/ZrO2 and HY zeolite, isomerization of hydrocarbon over WO3/ZrO2 sites, and subsequent hydrogenation of olefin intermediates over Pt.Catalytic hydrogenolysis of plastic waste has been performed in the presence of a solid acid-supported metal catalyst, where the C–C or C–hetero atom bond of plastic is cleaved by Hromatics . It is aromatics . Pt and romatics  preparedh et al.  demonstrc chains . Conversc chains  fabricat polymer . Lately,u et al. . The 2 h3–Csp3 bonds of polyolefin waste into short-chain hydrocarbons  at a wide range of experimental conditions  [2 [2 [2 [2O5) [2 catalyst was reported to be more effective (3-fold higher activity) than Ru/CeO2 catalyst for hydrogenolysis of LDPE [2) of PE, PP, and PS waste to grid-compatible methane with high selectivity and purity (>97%) using a Ru-modified zeolite (Ru/FAU) catalyst. Moreover, density functional theory (DFT) revealed a chain-end initiation process with a Ru-dominated reaction pathway. On the other hand, Hongkailers et al. [2 pressure) via C–O cleavage to produce arenes (xylene and toluene) using a Co/TiO2 catalyst. CuNa/SiO2 has been demonstrated to be able to convert PET to para-xylene (with high yield) and ethylene glycol by using methanol as both the solvent and H-donor resource [2O5 catalyst has also been reported [2 catalyst) to valuable gasoline and jet fuel range C7–C8 cycloalkanes and aromatics. Recently, Zhang et al. [2O3 in an autoclave (without no added solvent or H2) and heated to 280 °C for 24 h  was dissolved in hot chloroform to obtain the long hydrocarbons. In addition, the application of molybdenum (Mo)-based catalyst for the production of terephthalic acid (TPA) and ethylene by hydrogenolysis (at 260 °C under atmospheric H2) of PET waste has also been reported [Ruthenium (Ru) NPs supported on a carbon (Ru/C) catalyst (at 5 wt%) have been realized for hydrogenolysis of Csp 1–16 h) ,68,69. I16 h) [2 , TiO2 [7h) [2 [2 , WZrO2 [[2 [2 [2  and niob[2 [2O5) . The Ru/ of LDPE . Recentl of LDPE  reporteds et al.  demonstrresource . Lately,reported . Upcyclireported . In thisg et al.  demonstrfor 24 h a, where reported ,94.2) NP film for the depolymerization and complete mineralization of PP waste. While CO2 was found as the main end-product of PE photodegradation, the generation of hydroxyl, carbonyl, and carbon–hydrogen groups was obtained from PS photodegradation. Conversely, Tofa et al. [2) nanorods, which produced hydroperoxides, peroxides, carbonyl, and unsaturated groups. In a separate study, Reisner and co-workers [2 by the photoreforming of ground PET powder using solar light-simulated cadmium selenide/cadmium oxide (CdS/CdOx) quantum dots. The PET was first hydrolyzed in potassium hydroxide (KOH) solution to produce terephthalate, ethylene glycol (EG), and isophthalate, where EG was then photoreduced to yield H2, and the rest was photo-oxidized to produce formate, glycolate, ethanol, acetate, and lactate. The group also utilized a carbon nitride/nickel phosphide (CNx/Ni2P) catalyst for visible-light-driven PET reforming to produce clean H2 (2P) and reduce water to H2 [2 or platinized carbon nitride photocatalyst to obtain ethane/ethylene (with propanoic acid intermediate) and propane/propylene (with butyric acid intermediate), respectively.Another promising method for plastic waste upcycling is photoreforming, where depolymerization of plastic is performed under atmospheric conditions using light and a photoactive catalyst. UV-absorbing semiconductor nanoparticles are a promising photocatalyst for the depolymerization of PE and PS waste. For instance, Nabi et al.  studied a et al.  demonstr-workers  producedclean H2 b, where er to H2 . Lately,er to H2 . In this2 evolution at the cathode [2) using a Pd-modified Ni foam (Pd/NF) catalyst (2 and carbonate (95% selectivity). Similarly, Zhou et al. [2 using a CoNi0.25P catalyst.Electroreforming is a relatively less explored method for plastic waste upcycling, where depolymerization of plastic involves oxidative cleavage of the carbon–carbon bond at the anode and H cathode . Shi et  cathode  reportedcatalyst c. The pru et al.  demonstrAmong the various catalytic polymer processing methods developed, only catalytic pyrolysis, gasification, and crackling have reached a technology readiness level of 8–9 .Recent developments in biotechnology, such as enzyme-mediated biocatalytic depolymerization of plastic waste into value-added chemicals and utilization of depolymerized plastic waste as feedstock material for microbe-mediated biopolymer synthesis have emerged as sustainable and efficient methods for plastic waste upcycling ,98. The To date, various plastic-degrading enzymes have been discovered from different microbial sources a and havThe depolymerization of plastic waste by enzymes is a two-step process, where the enzyme first adheres to plastic surface by hydrophobic interaction, followed by the hydrolytic cleavage of the long polymer chains of plastic by the active site of the enzyme into smaller monomers or dimers, which can be accumulated or consumed by the microbial organism as a carbon source . On the Ideonella sakaiensis 201-F6, which could degrade PET and assimilate its monomers using two enzymes, designated as PETase and MHETase. This later led to the development of thermo-stable PETase from I. sakaiensis by rational protein engineering for highly efficient PET degradation [Psedomonas aestusnigri, Thermobifida fusa, and Clostridium botulinum, have also been developed to produce hydrolases, such as PETase, cutinase and esterase, for improved depolymerization efficiency [E. coli. Kim and co-workers [Escherichia coli, whereas waste PET-derived EG was fermented to glycolic acid (GLA) using Gluconobacter oxydans, as shown in E. coli strains. On the other hand, Magnin et al. [Yoshida et al.  first reradation , where Pficiency . The enzficiency  demonstrficiency  demonstr-workers  reportedn et al.  studied n et al. .P. putida GO16, P. putida GO19, and P. frederiksbergensis GO23, utilizing TPA (obtained from pyrolysis of PET waste) as the sole source of carbon and energy. The strains GO16 and GO19 accumulated PHA (predominantly of a 3-hydroxydecanoic acid monomer) at a maximal rate of approximately 8.4 mg PHA/l/h for 12 h, whereas the strain GO23 accumulated PHA (predominantly of a 3-hydroxydecanoic acid monomer) at a lower maximal rate of 4.4 mg PHA/l/h [PHA/gsubstrate) and hydroxyalkanoyloxy-alkanoates (HAAs) using P. umsongensis GO16 KS3 utilizing EG and TA (obtained by cutinase depolymerization of PET) as the carbon source. The authors also reported chemo-catalytic synthesis of bio-based poly(amide urethane) (bio-PU) using the obtained HAAs as monomers [P. putida KT2440 strain and utilizing EG as the carbon source. Conversely, Johnston et al. [Cupriavidus necator H16 and utilizing oxidized PP waste as an additional carbon source.Polyhydroxyalkanoates (PHAs) are biodegradable polyesters synthesized by various microorganisms in the presence of an excess amount of carbon sources and lack of macro elements such as phosphorus, nitrogen, trace elements, or oxygen . Several PHA/l/h . Recentl PHA/l/h  demonstrmonomers . In a semonomers  synthesin et al.  reported2, monomers, liquid fuels, grid-compatible gas streams, lubricants, waxes, and biodegradable polymers. Vitrimers, with their excellent re-processability and responsiveness, can be considered as next-generation smart circular materials, which can be synthesized with affordable technologies using conventional instruments that are operated in the polymer processing industries. Nanocomposite formulations comprising biomass represent a promising approach for the development of sustainable and compostable products, which could be easily implemented or adapted by polymer processing industries with the current infrastructure. However, the adaptability of 3D printing for large-scale production is still a long way away due to the slow build up speed. Emerging technologies like microwave, plasma, and supercritical water could provide synergistic effects to address the limitations for the further development of current technologies like pyrolysis, gasification, and solvolysis. Although the application of nanocatalysts has largely reduced the energy required for the chemical transformation of plastic waste, technological challenges related to the cost and performance of the catalyst, such as reaction and/or product selectivity, durability and/or recyclability, and removal and/or reusability, need to be addressed. Moreover, enzyme-meditated catalysis for plastic degradation and the production of bioplastic from non-conventional feed stocks using microorganisms will significantly reduce the carbon footprint. The envisaged circular economy necessitates the utilization of waste by different methods to minimize waste and ultimately carbon dioxide formation. Therefore, with the goal of ‘sustainable development with closed loop waste management’, the upcycling of plastic waste to biodegradable plastic needs to be part of the new thinking and should be considered as a means of valorization of post-consumer plastic.In summary, separate or mixed plastic waste can be effectively converted into value-added products by different upcycling approaches; including vitrimerization, nanocomposite fabrication, 3D printing and chemical and microbial transformations. Vitrimerization, nanocomposite fabrication, and 3D printing technologies can be potentially applied for the fabrication of new products with desired structural, mechanical, and functional properties. On the other hand, chemical and microbial transformation technologies can be adapted to obtain a diverse range of products including carbon allotropes, syngas, H


Epigenetic mechanisms involving DNA methylation and chromatin modifications have emerged as critical facilitators of cancer heterogeneity, substantially affecting cancer development and progression, modulating cell phenotypes, and enhancing or inhibiting cancer cell malignant properties. Not surprisingly, considering the importance of epigenetic regulators in normal stem cell maintenance, many chromatin-related proteins are essential to maintaining the cancer stem cell (CSC)-like state. With increased tumor-initiating capacities and self-renewal potential, CSCs promote tumor growth, provide therapy resistance, spread tumors, and facilitate tumor relapse after treatment. In this review, we characterized the epigenetic mechanisms that regulate the acquisition and maintenance of cancer stemness concerning selected epigenetic factors belonging to the Bromodomain (BrD) family of proteins. An increasing number of BrD proteins reinforce cancer stemness, supporting the maintenance of the cancer stem cell population in vitro and in vivo via the utilization of distinct mechanisms. As bromodomain possesses high druggable potential, specific BrD proteins might become novel therapeutic targets in cancers exhibiting de-differentiated tumor characteristics. Tumors are complex ecosystems in which distinct cell populations with divergent genomic and phenotypic profiles coexist and interact. Despite differing molecular backgrounds, those cell populations exhibit substantial differences in their metastatic ability, motility, proliferation, and differentiation potential . Among tFor the last several decades, enormous efforts have been undertaken to precisely characterize CSCs. However, it appeared extremely difficult as CSCs experience phases of transition between stem-like and non-stem-like states. Their phenotypical and functional properties are dynamically changing in response to genetic alterations, epigenetic factors, microenvironmental cues, or therapeutic agents, further adding to the complexity of cancer architecture .Epigenetic mechanisms involving DNA methylation and chromatin modifications have emerged as crucial facilitators of cancer heterogeneity, substantially affecting cancer development and progression, modulating cell phenotypes, and either enhancing or inhibiting cancer cell malignant properties . ChromatIn this review, we have characterized the epigenetic mechanisms that regulate the acquisition and maintenance of cancer stemness concerning selected epigenetic factors belonging to the Bromodomain (BrD) family of proteins . BromodoThe stemness of cancer cells is a crucial feature for cancer progression, encompassing enhanced capacity for self-renewal, giving rise to differentiated cells, and interacting with the environment to maintain the balance between proliferation and quiescence . To mainJAK/STAT, Hedgehog, Wnt/β-catenin, Notch, PI3K/Akt, TGF-β, and NF-κB signaling pathways have all been shown to facilitate various stem cell characteristics in normal stem cell development. In many tumor types, the abnormal activation of those pathways supports cancer progression by contributing to the survival of the cancer stem cell-like population (reviewed in ). Also, Many efforts have been taken to unequivocally define the CSC populations in distinct solid tumor types, resulting in the identification of many cell surface markers , that eTo maintain the cancer stemness in vitro, anchorage-independent growth  assays are frequently applied, as theoretically, both self-renewal and differentiation can be evaluated at the single-cell level ,22. SpheCSCs are endowed with a tumor-initiating capacity, and when injected subcutaneously into mice models, results in the formation of tumors (xenografts) that consist of CSCs and more differentiated progeny . This inTogether with investigating the ability for migration, invasion, and the assessment of the CSC markers’ expression, the sphere formation and xenotransplantation assays constitute the golden standard for quantifying cancer stemness both in vitro and in vivo.The Bromodomain (BrD) family of proteins encompasses 42 distinct members that possess at least one bromodomain—an evolutionarily highly conserved protein-interaction module that recognizes ε-N-lysine acetylation (Kac) motifs . BrD conBromodomain proteins were the first histone modification “readers” identified, displaying distinct specificity of histone recognition pattern. Therefore, BrD plays a critical role in orchestrating protein and DNA complexes at chromatin ,26. TheyBased on their functional divergence, Zaware et al.  have proThere are five BrD proteins that possess the histone acetyltransferase (HAT) activity, including KAT2A , PCAF (KAT2B), p300/CBP (EP300), TAF1  and TAF1L, in which the BrD and HAT catalytic domain are in close proximity. These birds are classified as group Ia ,30. The Albeit KMT2A  and ASH1L possess bromodomains, they are mostly known as SET domain-containing histone methyltransferases (HMTs) associated with transcriptionally active chromatin sites . The broThe III group of bromodomain proteins includes (i) the members of the SWI/SNF family of chromatin remodeling complexes (group IIIa), namely the SMARCA2 (BRM), SMARCA4 (BRG1), BRD7, BRD9, and PBRM1; and (ii) the members of the ISWI family of chromatin remodeling complexes (group IIIb), namely BAZ1A, BAZ1B, BAZ2A, BAZ2B, BPTF, and CECR2 . The chrIn SWI/SNF complexes, the SMARCA4 (BRG1) or SMARCA2 (BRM) bromodomain proteins, which are mutually exclusive, possess the ATPase activity, and their bromodomains could contribute to either assembly or targeting of the SWI/SNF complex to specific genomic loci . A recenThe ISWI complexes are one of the best-conserved ATPase families . They haATAD2 (ANCCA) and its paralog ATAD2B KIA1240) are the ATPase family members that contain the ATPases associated with diverse cellular activities (AAA) domains, as well as the bromodomain, and according to the functional classification proposed by Zaware et al. , both pr are the The V group of bromodomain proteins comprises BRD2, BRD3, BRD4, and BRDT proteins, which all possess two tandem bromodomains and an extra terminal (ET) and are known as the BET family . Except The VI group of BrD proteins that possess both the SUMO and ubiquitin E3 ligase activities is formed by four proteins collectively known as transcriptional intermediary factor 1 (TIF1) chromatin-binding proteins, namely TIF1α (TRIM24), TIF1β TRIM28) TIF1γ (TRIM33), and TIF1δ (TRIM66) . All mem TIF1γ (TThe VII group of BrD proteins encompasses four highly similar speckled proteins (SP)—SP100, SP110, SP140, and SP140-like protein (SP140L) ,26. TheyTwo well-known transcription regulators, ZMYND8 (RACK7) and ZMYND11, constitute the VIII group of BrD proteins ,30,51,52The IX group of BrD domains is formed by three WD-repeat proteins, namely BRWD1 (WDR9), BRWD3, and PHIP (WDR11), that possess two BrD units and several WD repeats . They shEpigenetic mechanisms that encompass diverse post-translational histone modifications, DNA methylation, chromatin remodeling, and even changes in non-coding RNAs, altogether dictate the outcome of cell fate specification. Not surprisingly, considering the importance of epigenetic regulators in normal stem cell maintenance, many chromatin-related proteins are essential to maintaining the CSC state ,17. IndeTo date, several BrD family members  were recognized and confirmed  as positive regulators/mediators of cancer stemness, while for the SMARCA2 protein—mostly negative roles in CSC maintenance were reported . HoweverKAT2A (GCN5) and KAT2B (PCAF)KAT2A and KAT2B are two highly homologous orthologues that exhibit a mutually exclusive pattern of expression. While KAT2A dominates in embryonal development, neural tissue differentiation, and hematopoiesis, KAT2B prevails in skeletal muscles. Only KAT2A is essential for proper embryonic development, stabilizing pluripotency gene regulatory networks and acting as a co-factor of the Myc transcription factor ,54. ConvIn contrast, KAT2B overexpression correlates negatively with cancer de-differentiation status, which is in line with the previously reported role of KAT2B in mediating differentiation of normal multipotent progenitor cells . HoweverP300/CBP (EP300)EP300 encodes a multi-domain protein that functions as acetyltransferase for both histone and non-histone targets. In somatic cell-induced reprogramming, p300 promotes acetylation of OCT4, SOX2, and KLF4 at multiple sites to change their transcription activity, thus regulating stemness acquisition . In cancTAF1 and TAF1LThe TAF1 gene encodes the largest subunit of the transcription factor II D (TFIID) in the RNA Polymerase II initiation complex, which promotes transcriptional initiation and activation . The TAFBRPF1, BRPF2, and BRPF3BRPF1 is a multivalent chromatin regulator, encoding several modules that recognize post-translational modifications on histone proteins, including double PHD fingers (targeting unmethylated histone H3), a bromodomain , and a PWWP domain (recognizes H3K36me3 mark). BRPF2 and BPRF3 are paralogs of BRPF1 with conserved domain architecture ,26.As a scaffold protein, BRPF1 interacts with the lysine acetyltransferases KAT6A, KAT6B, and KAT7, also known as MOZ, MORF, and HBO1, respectively. BRPF1 promotes the quartet-complex formation, restricts substrate specificity, and enhances the enzymatic activity of those acetyltransferases. BRPF2 preferentially associates with HBO1, assembling a chromatin complex required for the global acetylation of H3K14ac .Previously, You et al.  uncovereBRD8BRD8 has been recognized as a non-catalytic component of the conserved nucleosome acetyltransferase of the H4 (NuA4) complex, which is a multisubunit HAT mediating the acetylation of the N-terminal tail of histones H4 and H2A. The previous report demonstrated that BRD8 expression is associated with colorectal tumor progression toward advanced stages and may aid in gaining a growth advantage . BRD8 doKMT2AOne of the bromodomain proteins that possess intrinsic histone methyltransferase activity is an MLL1 protein encoded by KMT2A. MLL1 enzyme trimethylates H3K4 via its SET domain, mediating transcriptional activation ,30. The KMT2A was also demonstrated as essential for mediating cancer stemness in solid tumors. Grant et al.  have recASH1LASH1L encodes another bromodomain–containing HMT that can associate with actively transcribed loci, mediating dimethylation of H3K36 through its’ SET domain. An essential role for ASH1L was previously established in regulating normal stem cell maintenance, including hematopoietic stem cells and mesenchymal stem cells . ASH1L wSMARCA2 and SMARCA4SMARCA2 (BRM) or SMARCA4 (BRG1), both of which contain a C-terminal BRD module that can recognize acetylated histones H3 and H4 ,26, act In cancer, both SMARCA2 and SMARCA4 have emerged as critical tumor suppressors ,114, altRecently, we have demonstrated that SMARCA4 exhibit a consistent positive correlation with cancer stemness (assessed based on transcriptomic features of TCGA cancers). At the same time, SMARCA2—shows a negative association with tumor de-differentiation status, regardless of the tumor type . Indeed,The available data concerning SMARCA2 in cancer suggest that SMARCA2 function differs depending on the cancer type. In some tumor types, namely lung, kidney, and breast tumors, the event of SMARCA2 downregulation occurs during cancer de-differentiation (disease progression), suggesting a clonal selection of SMARCA2-abrogated cancer cells ,129,130.On the other hand, in pancreatic cancer, the upregulation of SMARCA2 associates with disease progression, being significantly positively correlated with patients’ poor survival, larger tumor size, metastases, lymphatic invasion, and stage IV disease . We haveBRD7 and PBRM1BRD7 and PBRM1 are additional bromodomain components of the polybromo-associated BAF (PBAF) class of SWI/SNF complexes, engaged in transcriptional regulation, DNA repair, and regulation of chromatin architecture and topology . FurtherIn embryonic stem cells, BRD7 is required for either activation or repression of specific genes, regulating stem cell self-renewal . InactivAn increasing number of studies have found that BRD7 expression is decreased or lost in human cancers, which is in line with its role as a tumor suppressor . PreviouOn the other hand, Zhao et al.  demonstrIn cancer, PBRM1 acts primarily as a tumor suppressor, and loss of PBRM1 was previously associated with the deregulation of expression of apoptotic and cell cycle regulatory genes , as wellBRD9A non-canonical BRD9-containing BAF (ncBAF) chromatin remodeling complex maintains naive pluripotency in mouse ESCs, and inhibition of BRD9 results in transcriptional changes representative of a primed epiblast-like state . RecentlIn cancer, degradation of BRD9-induced downregulation of oncogenic transcriptional programs inhibited tumor progression in vivo only in a synovial subtype of sarcomas  ,157. LatBAZ1B, BAZ2A, and BAZ2BBAZ1B  and BAZ2A  are relatively well-recognized in cancer-supporting programs. BAZ1B exerts oncogenic functions in breast, colorectal, and lung cancers ,166,167.As for BAZ2A, we observed either a positive or negative association with cancer de-differentiation, which seemed to be tumor-specific. However, Peña-Hernández et al.  revealedBAZ2B (the component of the BRF complex) engagement in regulating stemness was previously demonstrated in hematopoietic cells. As shown by Arumugam et al. , BAZ2B oBPTF and CECR2In normal embryonic stem cells, the BPTF (the component of the NURF complex) is required for proper cell differentiation, and mutations in BPTF result in a lethal phenotype (E8.5) . Also, BBPTF was previously identified as a tumor-promoting factor in several cancer types, including lung, liver, ovarian, gastric, colorectal, and brain cancers ,180,181.CECR2 (the component of the CERF complex) was recently reported to promote somatic cell reprogramming that worked through a protein network to overcome epigenetic barriers to induced stemness . The molATAD2ATAD2 takes part in a range of cellular activities, such as transcriptional regulation, chromatin remodeling, histone modification, and the formation of higher-order chromatin structures ,26,30. ATo date, there are several reports implying ATAD2 involvement in mechanisms related to cancer stemness. Specifically, Li et al.  have recPreviously, we reported a consistent positive correlation of ATAD2 expression with cancer stemness across distinct tumor types. We observed that higher-grade tumors displayed significant upregulation of ATAD2. Also, ATAD2-related transcriptome profiles were significantly enriched with known stem cell-derived gene signatures and “cancer hallmark” terms specific for stemness-high tumors, especially the activation of E2F and c-Myc-dependent transcription . This stBRD4Among the four mammalian BET family members, BRD4 and BRDT seem more closely related regarding the protein size or level of overall homology, while BRD2 and BRD3 manifest higher similarity to one another than to BRD4 or BRDT ,26.BRD4 knockout was previously shown to result in embryonic lethality . SimilarIn cancer, especially regarding cancer stemness, the involvement of BRD4 was most extensively studied. BRD4 is significantly upregulated in a number of cancer types, including melanoma, colon, breast, and bladder cancers ,195,196.BRD4 also promotes stemness in cancers of other types, including breast, gastric, esophageal, or prostate tumors. Shi et al.  reportedTaken together, BRD4 is a well-documented factor promoting cancer stemness across distinct types of solid tumors, and direct targeting of BRD4 significantly attenuates the cancer stem cell-like properties of tumors.TRIM24TRIM24  was previously identified as a part of the pluripotency network in mouse embryonic stem cells. Rafiee et al.  demonstrTRIM24 has been previously linked to promoting several types of solid tumors, including brain, breast, lung, kidney, ovarian, prostate, esophageal squamous, and head and neck squamous cell carcinomas ,216,217.TRIM28TRIM28 is expressed in all cell types, and high TRIM28 expression is observed in embryos and embryonic stem cells. TRIM28 plays a fundamental role in maintaining stem cell pluripotency, at least partially by repressing genes associated with differentiation and inducing the expression of stemness markers ,221,222.Moreover, the TRIM28 gene is highly expressed in different cancer types, including breast, glioma, liver, lung, gastric, kidney, ovarian, and pancreatic cancer, and higher expression frequently correlates with poor survival ,229,230.Recently, using the transcriptomic data from distinct types of solid tumors, we have reported that TRIM28 overexpression is significantly associated with an enriched stem cell-like phenotype regardless of the tumor type. Less differentiated tumors characterized by stem cell-like properties exhibit TRIM28 upregulation, and TRIM28-associated transcriptome profiles are robustly enriched with stem cell markers. Surprisingly, this phenomenon was strictly related to TRIM28 and not to other TIF1 family members .TRIM28 is a co-factor for a huge family of KRAB-ZNF transcription factors; some of them were previously recognized in mechanisms governing cancer stemness (reviewed in . TherefoTRIM33Previously, the TRIM33 protein was shown to regulate the proper differentiation of embryonic stem cells, in contrast to TRIM24 and TRIM28, which sustain self-renewal/pluripotency. Massague et al.  demonstrTRIM66The last member of the TIF1 family, TRIM66, has recently gained much interest in the context of cancerogenesis. Precisely, TRIM66 was identified as an oncogenic factor in glioma, osteosarcoma, lung, liver, and prostate tumors ,241,242.Although the abovementioned studies did not directly assess the involvement of TRIM66 in mediating cancer stemness, they strongly imply its stemness-promoting activity. Surprisingly, this finding contrasts with our previously reported work showing a negative association between TRIM66 expression and cancer stemness across most solid TCGA tumors . The traZMYND8ZMYND8 was previously recognized as a tumor suppressor in several types of tumors. However, recent studies uncovered its oncogenic potential. Luo et al.  have demIn contrast, Mukherjee et al.  observedThe role of BrD family members in cancer development and progression has been studied for years, although rarely with relevance to the stem cell compartment of heterogeneous tumors. A number of BrD proteins have garnered scientific interest for many decades, resulting in a relatively prominent role in cancerogenesis, while for other members—the experimental analyses are clearly missing. Here, we summed up the current knowledge about BrD proteins concerning cancer stemness, and also considered its cancer de-differentiation status. Stem cell-associated molecular features of solid tumors are essential in development, progression, therapy resistance, and cancer relapse. Therefore, a novel therapeutic strategy that would directly eradicate this population of cancer cells is urgently needed.We demonstrated that an increasing number of BrD proteins reinforce cancer stemness, supporting the maintenance of the cancer stem cell population in vitro and in vivo. Next to several well-known cancer stemness facilitators, including TRIM28 or BRD4, various other BrD proteins were recently proven to sustain stem cell-like phenotype via the utilization of distinct mechanisms. However, for most of the BrD members, further work is indisputable to fully characterize their contribution to cancer stem cell self-renewal machinery.In regard to the significant druggability of bromodomain, it would be of the highest importance to determine whether specific BrD protein members could serve as therapeutic targets in cancers exhibiting de-differentiated tumor characteristics. Ultimately, inhibition of those BrDs might result in the disruption of stemness-mediating machinery and, consequently, abolish tumor growth and prevent tumor relapse.


Interestingly, elimination of p21high cells in visceral adipose tissue can prevent or improve insulin resistance in mice with obesity, while p16high cell clearance is less effective in alleviating insulin resistance. Importantly, in immune-deficient mice transplanted with fat from obese patients, dasatinib plus quercetin, a senolytic cocktail that reduces the number of both p21high and p16high cells, improves both glucose tolerance and insulin resistance. On the other hand, in pancreatic β cells, p16high cells become increasingly predominant with age and development of diabetes. Consistently, elimination of p16high cells in mice improves both glucose tolerance and glucose-induced insulin secretion. Moreover, a senolytic compound, the anti-Bcl-2 inhibitor ABT263 reduces p16INK4a expression in islets and restores glucose tolerance in mice when combined with insulin receptor antagonist S961 treatment. In addition, efficacy of senotherapy in targeting mouse pancreatic β cells has been validated not only in T2DM, but also in type 1 diabetes mellitus. Indeed, in non-obese diabetic mice, treatment with anti-Bcl-2 inhibitors, such as ABT199, eliminates senescent pancreatic β cells, resulting in prevention of diabetes mellitus. These findings clearly indicate that features of diabetes are partly determined by which or where senescent cells reside in vivo, as adipose tissues and pancreatic β cells are responsible for insulin resistance and insulin secretion, respectively. In this review, we summarize recent advances in understanding cellular senescence in adipose tissues and pancreatic β cells in diabetes. We review the different potential molecular targets and distinctive senotherapeutic strategies in adipose tissues and pancreatic β cells. We propose the novel concept of a dual-target tailored approach in senotherapy against diabetes.Increased insulin resistance and impaired insulin secretion are significant characteristics manifested by patients with type 2 diabetes mellitus (T2DM). The degree and extent of these two features in T2DM vary among races and individuals. Insulin resistance is accelerated by obesity and is accompanied by accumulation of dysfunctional adipose tissues. In addition, dysfunction of pancreatic β-cells impairs insulin secretion. T2DM is significantly affected by aging, as the β-cell mass diminishes with age. Moreover, both obesity and hyperglycemia-related metabolic changes in developing diabetes are associated with accumulation of senescent cells in multiple organs, that is, organismal aging. Cellular senescence is defined as a state of irreversible cell cycle arrest with concomitant functional decline. It is caused by telomere shortening or senescence-inducing stress. Senescent cells secrete proinflammatory cytokines and chemokines, which is designated as the senescence-associated secretory phenotype (SASP), and this has a negative impact on adipose tissues and pancreatic β-cells. Recent advances in aging research have suggested that senolysis, the removal of senescent cells, can be a promising therapeutic approach to prevent or improve aging-related diseases, including diabetes. The attenuation of a SASP may be beneficial, although the pathophysiological involvement of cellular senescence in diabetes is not fully understood. In the clinical application of senotherapy, tissue-context-dependent senescent cells are increasingly being recognized as an issue to be solved. Recent studies have observed highly heterogenic and complex senescent cell populations that serve distinct roles among tissues, various stages of disease, and different ages. For example, in high-fat-diet induced diabetes with obesity, mouse adipose tissues display accumulation of  Diabetes mellitus is a growing issue of public health worldwide. In 2021, the estimated prevalence of patients with diabetes mellitus reached 537 million, and diabetes mellitus was responsible for 6.7 million deaths , and others 4/6 and preventing p53 degradation, respectively 7, B cell-specific Moloney murine leukemia virus integration site (BMI)1 and enhancer of zeste homolog 2, whose disruption downregulates repressive epigenetic marks of trimethyl histone H3K27 on the locus  are also involved in these regulations  . Cells if tumors . On the f tumors , resultif tumors . Moreovef tumors . A SASP ogenesis .Based on these ideas, either abrogation of chronic inflammation or elimination of senescent cells is emerging as a potential therapeutic strategy for aging-relevant diseases. Antibody therapy for inflammatory cytokines, e.g., interleukin (IL)-6 and tumor necrosis factor (TNF)-α, has already been clinically applied using molecularly targeted drugs. Recently, an anti-IL-1 antibody drug (canakinumab) was developed for treatment of some autoimmune diseases. Interestingly, the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) revealed that canakinumab prevented atherosclerosis and lung cancer among about 10,000 elderly people . This isIn this review, we summarize recent advances in understanding cellular senescence in adipose tissues and pancreatic β cells in diabetes. We review different potential molecular targets and distinctive senotherapeutic strategies in adipose tissues and pancreatic β cells. Consequently, we propose the novel concept of a dual-target tailored approach in senotherapy against diabetes.In globally aging societies, numbers of patients with multiple aging-relevant diseases are increasing. For example, a person diagnosed as hypertensive and diabetic with atherosclerosis may simultaneously be treated by another physician for osteoporosis and dementia, and all of these conditions are promoted or exacerbated by aging. Thus, medical costs for combinations of disease-specific drugs for their illnesses are increased, creating a serious burden for aging societies . If targBubR1, a checkpoint gene, was partly restored by p16Ink4 deletion, but not by ablation of p19Arf, which results in inactivation of the p53/p21Cip1 pathway  was shown to eliminate senescent cells  is well characterized, and is called fat senescence . The earreporter . Similarreporter , aged anreporter . Strikinreporter .Ink4 and p21Cip1 are observed during fat senescence. In progeria models, e.g. mice with BubR1 hypomorphic alleles, p53/p21 axis plays protective role for fat senescence  in murine WAT, apart from p16-high cells (p16Ink4-high-expressing (p16high) cells in WAT share senescence-like features. However, in WAT of obese mice, p21high cells, but not p16high cells, accumulated during the early stage of a high-fat diet (HFD)-feeding regimen (two months), while both were observed later (10 months). On the other hand, p16-high cells reside predominantly in the aged pancreas. Interestingly, recent findings suggested a significant role for p21Cip1 in SASP, called the p21-activated secretory phenotype (PASP)  as a molecular target for senolytic therapy  . PASP fu therapy . Analysied a HFD . Thus, fgh cells . While eCip1 is a potential candidate for senotherapy in human diseases, such as obesity-coupled diabetes, given that p21high cells are responsible for NF-kB dependent inflammation  at early stage, whose levels increases with age  and SASP ones , down-regulation of β cell markers , and up-regulation of genes that are usually suppressed in SA-β-Gal− β cells , along with increased SA-β-Gal (Gck), cellular depolarization , incretin signal pathways , and components of insulin granules   1 in aged rat β cells  . Other sng aging , 72, and β cells . Therefo+) secreted more SASP including IL-6, TNF, and CXCL1 than nonsenescent β cells  in C57BL6/J male mice  β cells revealed β-cell SASP signature proteins (+) β cells showed that human β-cell SASP is enriched in factors associated with similar pathways such as cytokine and IL signals, cellular responses to growth factors, and mitogen-activated protein kinase activation, while human β-cell SASP shares only several common factors with murine SASP, that is, AIP, MFRP, PAK6, KLK6, HDAC8, GPC6, and IDE (via enhancement of endoplasmic reticulum (ER) stress  stress –78. Thus+ cells in islets as well as expression of aging and SASP-related genes in islets  mice, a model of chronic ER stress, showed an increased tendency for p16INK4a and Bambi mRNA expression . Substitution of serine-64 with phenylalanine (S64F) in MAFA enhances the instability of MAFA protein and MAFAS64F male carriers can develop diabetes  protein, which is a β cell-enriched transcription factor that promotes β-cell maturation and function, can also be associated with senescence of β cells . It is kdiabetes , 82. In and H2Aγ . In the  factors . Moreove factors . Similar of T1DM . These fp21Cip1 (Cdkn1a) may be a candidate marker for early stage and/or an initial driver in β cell senescence, whereas another cell cycle arrest gene, p16INK4a (Cdkn2a) further maintains the cellular state , eliminated senescent β cells and reduced the incidence of diabetes in non-obese diabetic (NOD) mice . Islets feration . AlthougCip1 can be a hallmark of early-stage senescence and a main molecular target of senolysis to attenuate insulin resistance (INK4a can improve β cell functions and Bcl-2 can also be a molecular target of senolysis in pancreatic β cells, although clearance of p21high cells showed little effect on β cell functions (The last two decades of research have achieved remarkable advances in understanding of cellular senescence in adipose tissue and pancreatic β cells in diabetes, including their pathological role and contribution to development and progression of diabetes. Importantly, recent studies regarding senolysis have opened the possibility of senotherapy, a novel therapeutic concept, in diabetes. Since not only aging, but also metabolic stress, including insulin resistance, have had an impact on development, acceleration, and possible reversal of cellular senescence, individuals can harbor cellular senescence at different degrees even at the same age. Moreover, since potential distinctive markers and molecular mechanisms of cellular senescence have been discovered in adipose tissue and pancreatic β cells, degrees of cellular senescence and pathogenic contributions to diabetes can differ between these two major components of diabetes pathophysiology. In adipose tissue, p21sistance Figure 2TM and HK performed a literature search, wrote, and edited the manuscript. NI reviewed and edited the manuscript. All authors contributed to the article and approved the submitted version.NI received clinical commissioned/joint research grants from Daiichi Sankyo, Terumo, and Drawbridge Inc., speaker honoraria from Kowa, MSD, Astellas Pharma, Novo Nordisk Pharma, Ono Pharmaceutical, Nippon Boehringer Ingelheim, Takeda, Eli Lilly Japan, Sumitomo Dainippon Pharma, and Mitsubishi Tanabe Pharma, scholarship grants from Kissei Pharmaceutical, Sanofi, Daiichi Sankyo, Mitsubishi Tanabe Pharma, Takeda, Japan Tobacco, Kyowa Kirin, Sumitomo Dainippon Pharma, Astellas Pharma, MSD, Eli Lilly Japan, Ono Pharmaceutical, Sanwa Kagaku Kenkyusho, Nippon Boehringer Ingelheim, Novo Nordisk Pharma, Novartis Pharma, Teijin Pharma, and Life Scan Japan.The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. 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