Recent advances have also highlighted the crucial roles of posttranslational modifications (PTMs) of proteins in ferroptosis. Here, we summarize the recently discovered knowledge regarding the mechanisms underlying ferroptosis, particularly the roles of PTMs in ferroptosis regulation.Ferroptosis was first coined in 2012 to describe the form of regulated cell death (RCD) characterized by iron-dependent lipid peroxidation. To date, ferroptosis has been implicated in many diseases, such as carcinogenesis, degenerative diseases , ischemia-reperfusion injury, and cardiovascular diseases. Previous studies have identified numerous targets involved in ferroptosis; for example, acyl-CoA synthetase long-chain family member 4 (ACSL4) and p53 induce while glutathione peroxidase 4 (GPX4) and apoptosis-inducing factor mitochondria-associated 2  inhibit ferroptosis. At least three major pathways (the glutathione-GPX4, FSP1-coenzyme Q Over the past decades, more than ten types of cell death have been discovered and defined according to their different morphological characteristics, biomarkers, or regulatory mechanisms, and these include apoptosis, necroptosis, pyroptosis, and autophagy-dependent cell death –4. Ferroroptosis –7. Emergroptosis , 7. ReceGPX4 or the expression of inactive GPX4 causes embryonic death [GPX4 knockout mice were generated to analyze the cell death mechanisms induced by GPX4 inhibition [GPX4 knockout-induced cell death is largely reversed by the ferroptosis inhibitor liproxstatin-1 in a preclinical model of ischemia/reperfusion-induced hepatic damage [The selenoprotein GPX4 was the first identified central inhibitor of ferroptosis  Figure . Glutathic death , 11. Howic death . Thus, chibition –16. Unexc damage . Yang etc damage . Furtherc damage . Becausec damage . Ingold c damage . These sc- is the cysteine-glutamate antiporter, its activity is closely associated with the amount of GSH in the cell, and thus, this complex plays an important regulatory role in ferroptosis [Slc7a11) is well tolerated in unstressed mice [Slc7a11 deficiency induces tumor-selective ferroptosis and inhibits pancreatic ductal adenocarcinoma (PDAC) growth [Alox12 allele abrogates PUFA peroxidation and p53-mediated ferroptosis to accelerate tumorigenesis [+ T cells release interferon gamma (IFNγ), which upregulates interferon regulatory factor 1 (IRF1) and downregulates SLC7A11 and SLC3A2 in cancer cells to promote tumor cell lipid peroxidation and sensitize tumors to ferroptosis [The activity of GPX4 is not only directly inhibited by RSL3 but also inhibited by erastin or cystine deprivation through GSH depletion , 20. Becroptosis , 21. Altsed mice , Slc7a11) growth . PDAC ce) growth . Jiang e) growth . Further) growth . The losigenesis . Moreoveroptosis .10 is a mobile lipophilic electron carrier that endogenously synthesizes lipid-soluble antioxidants and acts as a lipophilic free radical-trapping agents (RTAs) in the plasma membrane [2) knockout cells and in cells treated with the CoQ2 inhibitor 4-chlorobenzoic acid (4-CBA) [2 is the enzyme that catalyzes the first step in CoQ10 biosynthesis, and idebenone, a soluble analog of CoQ10, is sufficient for suppressing ferroptosis and lipid peroxidation [10 antioxidant system  is a redox-active cofactor involved in the production of nitric oxide, neurotransmitters, and aromatic amino acids , 39. Thell death . The supll death . Althougll death . Intrigudetected . Thus, tc- [in vitro and in vivo studies [c- but with lower potency and less selectivity than erastin and its derivatives [c-, but further validation is needed [In 2003, Dolma et al. identified a small molecule (erastin) from a diverse chemical library that selectively kills engineered tumor cells through a nonapoptotic mechanism . Erastinc- , 21. Thec- , 21. Imi studies , 44, 45.ivatives . The coms needed , 47 , liproxstatin-1, phenoxazine, and roptosis , 17, 59.tability . Howevertability , whereascontexts , 28, 51,of CoQ10 , 51. In of CoQ10 –63. IronPTMs include phosphorylation, acetylation, ubiquitination, and methylation, SUMOylation, and most PTMs are reversible . These PAmpkα1/α2 double knockout (DKO) both in vitro in MEFs and in vivo in a mouse model of renal ischemia-reperfusion (I/R) injury [Phosphorylation is the most common type of PTM involved in the regulation of protein stability and enzyme activity, and these PTMs usually occur on serine, tyrosine, and threonine residues of the targeted protein , 67. Ene) injury . Mechani) injury . Moreove) injury . These rc- to promote ferroptosis. Furthermore, the knockdown of BECN1 represses system Xc- inhibitor -induced ferroptosis but not that induced by RSL3, FIN56, or buthionine sulfoximine; conversely, the overexpression of BECN1 or the administration of the BECN1 activator peptide Tat-Beclin 1 promotes cancer cell ferroptosis in vitro and in vivo [BECN1 does not affect the formation of lipidated microtubule-associated protein 1 light chain 3 (MAP1LC3B) and MAP1LC3B-positive puncta in ferroptosis [However, Song et al. demonstrated that the ferroptosis inducers erastin and sulfasalazine activate AMPK, which phosphorylates BECN1 at Ser90/93/96 and thereby facilitates BECN1-SLC7A11 complex formation  Figure . The int in vivo . Althoug in vivo , 73, theroptosis , 74. Theroptosis .Therefore, the aforementioned studies did not reach a unified conclusion regarding the effect of AMPK on ferroptosis. Because metformin is an AMPK agonist that not only lowers glycemia but also has great potential to relieve tumors , 77, wheκB) signaling pathway activates the expression of several proinflammatory cytokine genes that play pivotal roles in inflammatory disorders, such as sepsis, ulcerative colitis, myocardial infarction, and I/R injury [α, and interleukin- (IL-) 1β) induced by lipopolysaccharide (LPS) treatment, and these effects are mediated by inhibition of the phosphorylation of IκB kinase β (IKKβ) and the phosphorylation and degradation of IκBα and NF-κB and thereby lead to the suppression of sepsis development [κB directly binds to eukaryotic initiation factor 2α (eIF2α) to suppress the ER-stress-mediated ferroptosis of intestinal epithelial cells to alleviate ulcerative colitis [The Toll-like receptor 4- (TLR4-) nuclear factor kappa-light-chain-enhancer of activated B cells  and activates NFE2-related factor 2 (Nrf2) to inhibit ferroptosis in mice [In addition, folic acid-induced kidney injury is alleviated by pretreatment with FG-4592, an inhibitor of prolyl hydroxylase of hypoxia-inducible factor (HIF), which increases the phosphorylation of protein kinase B (Akt) and glycogen synthase kinase 3 in mice   has also been shown to be involved in the regulation of ferroptosis . Wang etin vivo studies, should be performed to validate these results. Because p53 is the critical regulator of ferroptosis and acetylation is crucial for the activity of p53 [3KR , an acetylation-defective mutant, fully retains the ability to suppress SLC7A11 expression but fails to induce cell cycle arrest, senescence, and apoptosis [4KR (K98R+3KR) completely abolishes its ability to regulate SLC7A11, but p53K98R alone exerts very modest effects on p53-mediated transactivation [4KR expression [Acetylation usually occurs in the lysine residues of target proteins, and this reaction is catalyzed by acetyltransferases and reversed by deacetylases . Acetylty of p53 , 64, 91,poptosis . Furthertivation . Moreovepression . These r+-dependent mitochondrial protein deacetylase that is involved in ROS production and cell death [Sirtuin 3 (SIRT3) is a prototypical NADll death . High coll death . In addill death  (Figure ll death  (Figure ll death .Protein methylation usually occurs on lysine or arginine, and both histones and nonhistone proteins can be methylated –106. A p10, and GCH1-BH4 pathways, are involved in ferroptosis regulation [in vivo studies and elucidation of the physiological functions of ferroptosis. Fourth, in addition to the phosphorylation, ubiquitination, acetylation, and methylation of proteins, whether other PTMs are involved in regulating ferroptosis remains unclear. Moreover, the mechanism through which these PTMs work together in the ferroptosis process has not been elucidated. Fifth, because ferroptosis can be induced through many different mechanisms, clarifying the specific and shared PTMs that play roles under different conditions that induce ferroptosis would be interesting. Sixth, numerous targets and their PTMs that induce and inhibit ferroptosis have been identified, and whether drugs targeting these targets can be transformed to clinical treatment for patients and their safety and efficacy need further investigation.Due to the growing number of laboratories devoted to investigating the mechanisms and functions of ferroptosis, the research on ferroptosis is unprecedentedly prosperous. Recent studies have shown that ferroptosis plays a critical role in many diseases, including tumorigenesis, I/R injury, neurological disorders, and cardiovascular diseases , 112–114gulation . Moreove


Background: Although remdesivir treatment is widely used during the pandemic coronavirus disease 2019 (COVID-19), there is scarce evidence regarding its cardiac side effects. Case presentation: We report the case of a 36-year-old male hospitalized due to severe COVID-19 symptoms. He presented with a 10-day history of fever (up to 39.7 °C), productive cough, hemoptysis, fatigue, myalgias and hypoxemia. The patient received supplemental oxygen, dexamethasone, remdesivir and empirical antibiotic treatment according to protocol. Asymptomatic sinus bradycardia developed on hospital day 3 . Secondary causes of bradycardia were excluded based on the absence of relevant evidence from laboratory work-up and echocardiographic examination. The patient’s rhythm restored to normal 9 days after the discontinuation of remdesivir. Conclusions: Considering the frequent use of remdesivir in patients with COVID-19, physicians should be aware of this possible adverse event. At the end of 2019, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was identified as the cause of a cluster of pneumonia cases in Wuhan, in the Hubei Province of China and finally declared a pandemic in February 2020 , there iA 36-year-old male presented with a 10-day history of fever up to 39.7 °C, productive cough with hemoptysis, fatigue and myalgias. Polymerase chain reaction (PCR) testing of a nasopharyngeal sample confirmed SARS-CoV-2 infection, and the patient was admitted to the Infectious Disease Unit of the University Hospital of Ioannina, Greece.2: 88%, partial pressure of oxygen; PO2: 59.3 mmHg) while breathing room air. He was put on supplemental oxygen . An electrocardiogram (ECG) revealed normal sinus rhythm (heart rate 92/min). Body mass index was 35.3 kg/m2. Laboratory tests are shown in On admission, the patient was febrile (body temperature 38.5 °C) but hemodynamically stable (blood pressure 113/72 mmHg). Analysis of arterial blood gases showed hypoxia , dexamethasone 6 mg qd, remdesivir (a loading dose 200 mg on day 1 followed by 100 mg qd), and low molecular weight heparin for thromboprophylaxis (enoxaparin 60 mg bid).2 was 89 mmHg on oxygen supplementation (FiO2 = 36%).On hospital day 3, there was evidence of asymptomatic sinus bradycardia (39 bpm) . The patPhysical examination was unrevealing while extensive laboratory evaluation and echocardiogram was not indicative of secondary causes of sinus bradycardia, such as myocardial ischemia, myocarditis, thyroid dysfunction, electrolyte disorders or massive pulmonary embolism. Sinus bradycardia was deemed to be related with remdesivir treatment, which was accordingly discontinued. Heart rate gradually restored to normal. On hospital day 12, the patient required no supplemental oxygen and an ECG showed sinus rhythm with a heart rate of 58/min .Herein, we report a case of possible remdesivir-associated sinus bradycardia in a patient with severe COVID-19. To the best of our knowledge, there is a handful of reports in the literature, with ours being the third case report.SARS-CoV-2 has been associated with cardiovascular complications, including myocardial infarction, myocarditis and rhythm abnormalities ,8. ArrhyRemdesivir, a nucleoside analogue prodrug acting as an RNA polymerase inhibitor, has been shown to shorten the time to recovery in hospitalized adults with severe COVID-19 requiring low-flow supplemental oxygen ,3. FrequOur case adds to the scarce evidence of remdesivir therapy related with sinus bradycardia ,5. ThreeTaking into account the incorporation of remdesivir in treatment protocols of COVID-19, clinicians, who are currently watching with a vigilant eye for cardiac rhythm abnormalities in these patients, should be aware of the reversible association of remdesivir with sinus bradycardia.


In addition to the role of RNA modifications in brain tumor progression, we will also discuss potential opportunities to target these processes to improve the dismal prognosis for brain tumors.RNA modifications are emerging as critical regulators in cancer biology, thanks to their ability to influence gene expression and the predominant protein isoforms expressed during cell proliferation, migration, and other pro-oncogenic properties. The reversibility and dynamic nature of post-transcriptional RNA modifications allow cells to quickly adapt to microenvironmental changes. Recent literature has revealed that the deregulation of RNA modifications can promote a plethora of developmental diseases, including tumorigenesis. In this review, we will focus on four key post-transcriptional RNA modifications which have been identified as contributors to the pathogenesis of brain tumors: m Of the approximately 25,000 people diagnosed annually with primary malignant brain tumors in the USA, 80% are gliomas, one of the most lethal types of cancer , 131. Am6-methyladenosine (m6A), were previously limited by the inability to distinguish between certain nucleotides during reverse transcription [1-methyladenosine (m1A) and 5-methylcytosine (m5C), which are not found only in mRNA: m5C can also be found in transfer RNA (tRNA) and m1A in tRNAs, ribosomal RNAs (rRNAs) and long non-coding RNAs (lncRNAs) [6A, alternative polyadenylation (APA), alternative splicing, and adenosine to inosine (A-to-I) modifications. RNA modifications are a highly conserved mechanism utilized by eukaryotes throughout phylogeny to enhance biologic complexity [Before messenger RNA (mRNA) translation and protein synthesis can occur, nascent mRNA transcripts require processing and nucleic acid modifications. These include splicing out of introns, the non-coding sections of the transcripts, as well as methylation of certain bases. RNA modifications modulate most steps of gene expression, from indirectly controlling DNA transcription, by regulating expression of mRNAs encoding transcription factors, to directly affecting mRNA translation , 144. Whcription , 96. Howcription , 65, 69.lncRNAs) , 96. WitlncRNAs) . These mmplexity . RNA modmplexity . This memplexity . In contmplexity . This almplexity , 100. Whmplexity , 84, a cN6-methyladenosine (m6A) makes up the majority of the internal mRNA modifications in eukaryotes, and has emerged as a critical regulator in many aspects of RNA biology, including pre-mRNA splicing, polyadenylation, localization, and mRNA translation [6A is catalyzed by methyltransferases, demethylases, and binding proteins, otherwise known as “writers,” “erasers” and “readers”, respectively [6A generally occurs within long exons, around stop codons, and in 3′ untranslated regions (3′-UTRs) [6A writers are also located in intronic RNA regions [6A methylation may occur co-transcriptionally, before or during splicing. In addition, mRNA splicing factor precursors co-localize with m6A methyltransferases in nuclear speckles, suggesting the involvement of intronic m6A residues in alternative splicing [Of the known RNA modifications, the methylation of adenosine at the nitrogen-6 position to create nslation , 27, 95.ectively . M6A gen3′-UTRs) , 141. Ho regions , indicatsplicing , 69.6A can be added or removed facilitates rapid changes in gene expression, as m6A modifications are reported to promote mRNA decay through binding of specific degradative protein complexes [6A mRNA methylation, the multi-subunit writer complex comprises a catalytic subunit, known as methyltransferase-like 3 (METTL3), a second augmenting methyltransferase subunit (METTL14) utilized in substrate recognition, as well as the Wilms’ tumor 1-associating protein (WTAP) [6A modifications by promoting the recruitment of the METTL3-METTL14 complex to target mRNAs, in addition to inducing the translocation of the complex to nuclear speckles [WTAP mutations are extremely rare in cancer, occurring in only 0.5% of gliomas [The relative ease by which momplexes , 140. Thomplexes . To catan (WTAP) , 82, 127speckles , 69. WTAspeckles . WTAP mu gliomas . Instead gliomas . Moreove gliomas . While f6A readers” selectively bind to mRNAs modified with m6A. The specific type of reader protein regulates different functions: binding of YTH domain containing family protein (YTHDC1) to m6A induces mRNA splicing by recruiting splicing factor SRSF3 [6A [YTHDF1 and YTHDF2 mutations only occur in 0.9 and 0.5% of glioma cases respectively [6A readers in glioma progression [Proteins often referred to as “mor SRSF3 , whereasor SRSF3 , 50, 128or SRSF3 . To faciRSF3 [6A , 136. Whgression , 112. Whgression . Using pgression . While tgression . Althouggression , 105. It6A methylation is catalyzed by demethylases known as fat mass and obesity-associated protein (FTO), and ALKBH5 [6A modifications [ALKBH5 and no mutations have been reported in FTO [6A primary antibodies and performed microarray analysis. This approach identified ALKBH5 mRNAs targets, such as the proto-oncogene FOXM1. Demethylation of m6A residues in the 3′-UTR of the FOXM1 pre-mRNA results in increased transcript stability and enhanced FOXM1 protein expression [The reversal of md ALKBH5 , 146, boications , 146. Ind in FTO . Howeverd in FTO , is linkd in FTO , 143. Topression . Demethypression .METTL3 locus arise in ~ 1% of gliomas [6A levels are elevated in glioma compared to normal brain [ADAM19 and KLF4 were upregulated by METTL3 silencing and tumor suppressors such as CDKN2A and BRCA2 were downregulated. However, more recent work suggests a different scenario. Visvanathan et al., utilizing methylated RNA immunoprecipitation-seq (MeRIP-seq) on glioma cell line MGG8, followed by gene set enrichment (GSEA) and Gene Ontology (GO) analyses, proposed that METTL3 silencing may in fact disrupt tumorigenic pathways that facilitate glioma progression, such as NOTCH, c-Myc and NFκB [METTL3 significantly decreased proliferation of GBM cell lines U251 and U87MG in cell viability assays [According to the TCGA, genetic amplifications at the  gliomas . In addial brain , 125, thal brain . As a poand NFκB , 125. Thy assays . In vivoy assays . While iy assays , 108. Noy assays .6A methylation regulators are also emerging as critical components of GBM tumorigenesis [6A modifications are differentially expressed between different glioma grades. Specifically, there is positive correlation between WHO grade and expression of WTAP, YT521-B homology (YTH) domain containing family (YTHDF) and AlkB homolog 5 (ALKBH5), whereas there is a negative correlation between FTO and WHO grade [6A deposition around the start codon of serine and arginine rich splicing factor (SRSF) mRNAs. The methylation around the start codon then prevents NMD of SRSF mRNAs, thus resulting in increased alternative splicing and isoform switching in glioma [Additional migenesis , 126. ChHO grade . These rHO grade . A possin glioma .APA is a mechanism that allows a single gene to encode multiple mRNAs, and represents a critical post-transcriptional regulator of gene expression . For theThe process of polyadenylation is facilitated by a multimeric protein complex comprised of four primary subunits: the cleavage and polyadenylation specificity factor (CPSF), cleavage stimulation factor (CSTF), mammalian cleavage factor I (CFIm) and cleavage factor II (CFIIm) , 40, 120One of the subunits of the CFIm complex, CFIm25, is believed to directly facilitate the recognition of certain PAS sequences, especially those rich in UGUA sequences . Depleti6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that acts to convert methylguanine back to guanine by removing the methyl or akyl group from the O6 position of guanine, without causing breaks in the DNA. Promoter methylation of the MGMT gene in GBM, present in over 40% of cases, results in improved survival in patients treated with TMZ in addition to radiotherapy [Ootherapy . APA hasotherapy . This lootherapy . Importaotherapy , 60. ThiAs mentioned, following transcription, processing of the pre-mRNA transcript precedes downstream translation and protein synthesis. In addition to the modifications discussed above, splicing results in the formation of multiple mRNA and protein isoforms from one gene Fig. . AlternaThe ubiquitous presence of alternative splicing within cells underscores its relevance for the pathogenesis of tumors, including GBM. Glioma, as described for many other tumors, display a high degree of intertumor heterogeneity , 124. AmMKNK1 and MKNK2 genes are rare in cancer, being present in 0.5 and 2.4% of cases respectively in glioma [PTCH1 while activating oncogenic genes such as GLI2 and CCND2 [The MAPK interacting kinase (Mnks) family of proteins include MNK1 and MNK2 and are the kinases responsible for phosphorylation of eukaryotic translation initiation factor 4E (eIF4E) on Ser-209 . While gn glioma , both prn glioma . Previoun glioma , 42. A rn glioma . Unfortun glioma . On the n glioma . Typicaln glioma , 66. Then glioma , 133. Asn glioma . Finallyn glioma . This rend CCND2 . While nseed sequence (the miRNA recognition site in RNAs), affecting target specificity of the mature miRNA [A-to-I modifications comprise the irreversible, hydrolytic deamination of adenosine nucleoside bases by adenosine deaminases acting on dsRNA (ADARs), converting the adenosine to inosine in RNAs , 98, 106re miRNA , 57, 137re miRNA .Fig. 3TADARB1 gene occur only in 0.6% of cases [seed sequence [While found in all human tissues, A-to-I editing is most prevalent in the brain, and aberrant editing is linked to the development of various brain pathologies including amyotrophic lateral sclerosis, Alzheimer’s disease, Parkinson’s disease, epilepsy and glioma , 93, 107of cases , ADAR2 asequence . In the sequence , 58, 74.GBM is known to utilize glutamate to promote proliferation and migration , a proce, it is unlikely that ADAR3 can directly edit pre-mRNA transcripts. However, as ADAR3 is known to bind to dsRNA despite not being able to perform A-to-I modifications, it has been hypothesized that ADAR3 could act as a direct physical block, preventing ADAR2 from mRNA binding and subsequent editing [In other studies, the activity of ADAR2 was deemed essential to prevent glioma proliferation and growth through the editing of the CDC14B pre-mRNA transcript involved in the Skp2/p21/p27 pathway . As ADAR editing . An alte editing . SequestThe studies outlined in this review highlight the importance of RNA modifications in brain tumor progression, specifically in glioma. The flexibility conferred by post-transcriptional control adds another dimension by which gene expression can be regulated beyond what is directly coded from DNA. The addition of multiple modifications on the same transcript could thus increase the complexity of multiple regulatory networks. This plasticity is particularly relevant for cancer cells to adapt to unexpected microenvironmental changes. However, as showcased throughout this review, deregulation of the RNA modification machinery and altered gene expression are associated with many of the hallmarks of cancer, such as apoptosis evasion and uncontrolled proliferation. Given the significant contribution to brain tumor malignancy, greater emphasis on clarifying the role of RNA regulation and modifications in glioma progression is needed. Targeting the regulatory enzymes controlling the post-transcriptional modifications discussed in this paper warrants further detailed investigation, as this remains an unexplored strategy that could ultimately improve the prognosis of brain tumor patients.


The pathogenesis of Parkinson’s disease (PD), the second most common neurodegenerative disorder, is complex and involves the impairment of crucial intracellular physiological processes. Importantly, in addition to abnormal α-synuclein aggregation, the dysfunction of various mitochondria-dependent processes has been prominently implicated in PD pathogenesis. Besides the long-known loss of the organelles’ bioenergetics function resulting in diminished ATP synthesis, more recent studies in the field have increasingly focused on compromised mitochondrial quality control as well as impaired biochemical processes specifically localized to ER–mitochondria interfaces . In this review, we will discuss how dysregulated mitochondrial crosstalk with other organelles contributes to PD pathogenesis. Parkinson’s disease (PD), the most common movement neurodegenerative disorder, is a complex multifactorial disease with an incidence range between 5 up to >35 per 100,000 population .Familial and sporadic PD forms share common clinical, pathological, and biochemical characteristics. Although many aspects of PD pathogenesis remain elusive, dysregulation of various fundamental physiological processes has been implicated, including impairment of the ubiquitin-proteasome pathway, mitochondrial dysfunction, oxidative stress, and neuroinflammation.Both environmental and genetic factors converge in the complex molecular pathophysiology of Parkinson’s disease, with mitochondrial dysfunction playing a major role ,4,5,6. AWe specifically focus on how dysregulated communication of mitochondria with endoplasmic reticulum and lysosomes as well as compromised quality control at the mitochondrial level contribute to PD pathogenesis. For each interorganellar contact, we first provide a brief overview on their physiological organization and functions, and then describe how PD-linked genes affect these functions .The close apposition between ER and mitochondria was first described as an interorganellar contact by Bernhard in 1956  and lateReflecting their biochemical functions in lipid metabolism, MAMs are enriched in proteins such as phosphatidyl ethanolamine methyltransferase 2 (PEMT2), phosphatidylserine synthase 1 and 2 (PSS1/2) ,16, and Lipid synthesis, in particular the synthesis of triacylglycerol, phosphatidylcholine (PC), and phosphatidylethanolamine (PE), requires enzymatic activities associated with both ER and mitochondria. Phosphatidylserine (PS) is synthesized from PA by PSS1 in MAMs and is converted to PE by PS decarboxylase in mitochondria. One of the enzymes implicated in the final steps of PC synthesis, PEMT2 , was fouAnother enzyme located at ER–mitochondrial contact sites is acyl-CoA/diacylglycerol acyltransferase 2 (DGAT2), which catalyzes triacylglycerol synthesis and promotes lipid droplet formation . MAMs ar2+ homeostasis [2+ channel inositol-1,4,5-triphosphate (IP3) receptor (IP3R) at these contact sites [2+ signaling hubs providing ER-to-mitochondria Ca2+ transfer to maintain cellular bioenergetics, mitochondrial dynamics and transport, and also to modulate cell death decisions [Besides their role in lipid metabolism, MAMs are also critically involved in Caeostasis ,21,22, act sites ,24. IP3Rct sites . Thus, Mecisions ,27,28.2+ release from the ER through IP3Rs forms microdomains with high Ca2+ concentrations, which are important for the Ca2+ uptake into the mitochondrial matrix [2+ uptake involves its diffusion across voltage-dependent anion channels (VDACs) of the outer mitochondrial membrane (OMM) [2+ concentrations modulate the enzymatic activities of mitochondrial ATP synthase and of the dehydrogenases that provide reducing equivalents to the respiratory chain [2+ [2+ homeostasis is facilitated by cytosolic Ca2+ re-uptake into the ER through the sarco/endoplasmic reticulum (SR/ER) Ca2+ ATPase pump (SERCA) [2+ fluxes enhance upon increased energy demand [2+ transfer can initiate programmed cell death through mitochondrial Ca2+ overload and opening of the mitochondrial permeability transition pore, leading to pro-apoptotic mediator release from mitochondria with subsequent effector caspase activation [The stimulation of Cal matrix ,29. Mitone (OMM)  and the ne (OMM) ,32. Indery chain ; they alhain [2+ . Ca2+ ho (SERCA) . While Cy demand , excessitivation .2+ channel in ER–mitochondria tethering [IP3R interacts with the OMM protein voltage-dependent anion channel isoform 1 (VDAC1) through glucose-regulated protein 75 (GRP75), a member of the Hsp70 family of chaperones, forming an interorganellar tethering complex between ER and mitochondria . Howeverethering . As discClose physical, bidirectional interactions between ER and the mitochondrial network also play an important role in mitochondrial fission. The mitochondrial adaptors syntaxin 17, Mff, MiD49, and MiD51 that are involved in the recruitment of the fission-promoting dynamin-related protein Drp1 localize to ER–mitochondria interfaces ,38. ER t2+ concentrations, mitochondria move at maximal velocity, while their motility is reduced at IP3R-dependent Ca2+ hotspot regions, so that mitochondria accumulate and enhance local Ca2+ buffering by Ca2+ uptake which represents an important feedback mechanism in Ca2+ signaling [In addition, MAMs are also involved in the regulation of mitochondrial retrograde and anterograde transport along microtubules. In this context, at resting cytosolic Caignaling .The protein composition of some tethering complexes at MAM level continues to be a matter of debate. While Mitofusin 2 (MFN2), localized both on the ER and OMM, has been implicated in regulating ER–mitochondria juxtaposition, the field is still divided on the question of whether it functions as tether ,43,44 or2+ exchange and modulates interorganellar contacts, as assayed by EM. Beyond its Ca2+ exchange function, this ER-mitochondria tethering complex was also proposed to play a role in autophagy regulation [Various proteins localized at ER–mitochondria interface such as PACS-2  and GRP7gulation . In addigulation .2+ homeostasis, and autophagy. While many of these functions are compromised in neurodegenerative disorders including Parkinson’s disease (PD), it is still unclear whether MAM dysregulation is cause or consequence of the pathogenic processes leading to neurodegeneration. Nevertheless, it seems clear that MAM dysfunction can accelerate neuronal death. Both changes in the number of contacts between ER and mitochondria, and impairments of their functionality have been associated with PD [MAMs serve crucial functions in various signaling pathways and metabolic processes, including mitochondrial bioenergetics and dynamics, Ca with PD ,54,55.Mutations in several PD-associated genes have been causally related to mitochondrial dysfunction. Even if our current knowledge about the role of PD-related proteins in ER–mitochondria crosstalk is still far from complete, the following sections highlight their roles in maintaining MAM structure and function.SNCA was the first gene to be associated with familial cases of PD [2+ exchange and the physical interaction between ER and mitochondria, as reported by different groups, with still-debated downstream effects [es of PD . It encoes of PD ,58, refles of PD , where ies of PD ,61. α-sy effects ,62,63.α-syn presence has important implications for mitochondrial integrity: expression of either the α-syn disease mutation A53T at low levels, or of wild-type α-syn at high levels, result in fragmented mitochondria . The mitImportantly, a portion of α-syn seems to be localized at MAMs , consistPathogenic mutations of α-syn affect its binding to lipid membranes , as exemThis reduced MMP could promote OPA1 cleavage and consequently mitochondrial fragmentation . In addiAlthough α-syn was shown to be a major component of Lewy bodies more than 20 years ago , subsequAggregated proteins and damaged organelles are removed from the cytoplasm by autophagic mechanisms . MitophaIntriguingly, two PD-associated proteins, PTEN-induced putative kinase 1 (PINK1), a mitochondrially localized kinase, and Parkin, a cytosolic E3 ubiquitin ligase, are the two key players of this mitophagic quality control system. Mutations in PINK1 and Parkin are linked to early-onset familial PD , and extUnder basal conditions, PINK1 is imported into mitochondria through the translocase of the outer membrane (TOM) complex and then through the translocase of the inner membrane complex (TIM) into the matrix, where it is cleaved by the matrix processing peptidase and the inner membrane protease presenilin-associated rhomboid-like protease (PARL) ,83,84. TRelevant to the ER-mitochondria interface, Parkin was also shown to ubiquitinate MFN2, VDACs and Miro . BECN1/B2+ signaling [Fibroblasts from patients carrying mutated PINK1 or Parkin display increased ER–mitochondria juxtaposition, resulting in aberrant ER-to-mitochondria Caignaling ,94. SimiParkin and PINK1 null mice generally fail to recapitulate the degeneration of dopaminergic neurons in the SN ,96,97. FParkin was reported to co-regulate ER–mitochondria contact sites together with the transcription factor peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a key modulator of mitochondrial biogenesis . Loss ofParkin has a Ser65 residue within its N-terminal ubiquitin-like (UBL) domain, similar to that of ubiquitin. This residue is phosphorylated by PINK1, resulting in an open and active conformation ,103. ChaPINK1-deficiency in Drosophila, mouse models and patient-derived cells resulted in mitochondrial complex I defects  and decrThe DJ-1 protein serves a broad variety of functions. It plays an essential role in sensing and reacting to oxidative stress, thereby protecting cells against reactive oxygen species (ROS) ,108. WitIn addition to oxidative stress, DJ-1 protects against other toxic agents by modulating PTEN activity and Akt signaling ,114, eit2+ transfer between the two organelles, thereby maintaining mitochondrial function and structure. Depletion or lack of function of this protein causes alterations of mitochondrial morphology, decreases mitochondrial membrane potential, reduces ER-to-mitochondria Ca2+ transfer and impairs mitochondrial motility in neurites [DJ-1 protein localizes at MAMs where it modulates ER–mitochondria interactions and consequently Caneurites .Whereas mutations in the gene encoding DJ-1 (PARK7) lead to familial early-onset PD, the exact mechanisms underlying its role in PD pathogenesis still remain elusive ,122. In Leucine-rich repeat kinase-2 (LRRK2) is a large, multi-domain protein involved in a number of functions, such as GTP hydrolysis, kinase activity, and protein binding. Even though its cellular function is largely unknown, emerging evidence attributes to LRRK2 roles in autophagic regulation, microtubule dynamics, and mitochondrial function. In addition to being localized mainly to the cytoplasm, some LRRK2 also resides at mitochondria .Autosomal dominant LRRK2 mutations are associated with both familial and sporadic PD ,126. ExpLRRK2 interacts with a number of mitochondrial fission/fusion regulators, either in the cytosol or on mitochondrial membranes . It was LRRK2 also interacts and modulates the activities of the mitochondrial fusion regulators MFN1, MFN2, and OPA1. Indeed, PD patients carrying the G2019S mutation showed decreased levels of L-OPA1 . MoreoveLRRK2 kinase activity also regulates ER–mitochondrial tethering by modulating the PERK-dependent ubiquitination pathway under ER stress conditions. In this context, LRRK2 interacts with the E3 ubiquitin ligases MARCH5, MULAN, and Parkin, thereby blocking PERK-mediated phosphorylation and activation of these E3 ubiquitin ligases. Kinase-active LRRK2 (G2019S) dissociates from ER ubiquitin ligases, allowing PERK to phosphorylate and thereby activate these enzymes towards MAM components, impinging on ER–mitochondrial tethering .Another crucial aspect of mitochondrial dynamics in the context of neurodegeneration is mitochondrial trafficking, where mitochondrial locomotion is tightly controlled to preserve energy homeostasis. Before the initiation of the mitophagy cascade, mitochondrial motility halts, enabling the sequestration of damaged mitochondria. This arrest of depolarized mitochondria is achieved by removal of the Miro protein from the mitochondrial surface; this process is promoted by LRRK2, which forms a complex with Miro, targeting it for PINK1/Parkin-dependent degradation . InteresLysosomes, together with mitochondria, are critical for the maintenance of cellular homeostasis, as reflected by the fact that dysfunction of both organelles is functionally and genetically linked to several human diseases ,137,138.Whereas numerous reports have demonstrated indirect functional interactions between mitochondria and lysosomes ,146,147,Mitochondria–lysosome contact sites have been imaged in various cell types under healthy conditions taking advantage of different techniques, such as 2D and 3D electron microscopy ,154, corThe small GTPase Rab7 is a master regulator of lysosomal maturation, positioning, and network dynamics . As evidVacuolar sorting protein 35 (VPS35) is a key component of the retromer complex, involved in intracellular protein trafficking. VPS35 mediates retrograde delivery of cargo from endosomes to Golgi, as well as recycling endosomal cargo to the cell surface ,167.The retromer can be divided into a cargo-selective complex (CSC) trimer composed of VPS26, VPS29 and VPS35, involved in binding and sorting protein cargo ,169, andVPS35 has a role in the formation of MDVs, which shuttle cargo from mitochondria to either peroxisomes or lysosomes, being so involved in mitochondria quality control ,170. ThiRemarkably, the VPS35 D620N mutation is associated with autosomal-dominant PD ,180. PD VPS35 can also impinge on mitochondrial dynamics by an MFN2-dependent mechanism. A proteomic study suggested that VPS35/retromer interacts with the OMM E3 ubiquitin ligase MUL1  . VPS35 pPARK9 gene encodes the protein ATP13A2, a transmembrane lysosomal type 5 P-type ATPase [2+-modulating activity of ATP13A2 [2+ dyshomeostasis [The e ATPase , which he ATPase ,186,187. ATP13A2 ,189,190,eostasis ,192,193 The analysis of fibroblasts from two patients with the L3292 and L6025 ATP13A2 mutations showed an impaired clearance of autophagic vacuoles, accompanied by impaired lysosomal acidification, cathepsin activity, and proteolytic capacity, while the delivery of substrates to lysosomes by either macroautophagy or chaperone-mediated autophagy (CMA) translocation did not seem to be affected . α-syn cPD-linked mutations in ATP13A2 may result in insufficient clearance of α-syn through lysosomes, resulting in its accumulation in the cytosol. Furthermore, postmortem nigral tissue samples from sporadic PD patients exhibited decreased neuronal levels of ATP13A2, which appeared to be mostly trapped in Lewy bodies  Figure b.Beside its involvement at MAMs (described above), LRRK2 serves a critical role in the autophagic pathway at the lysosomal level. During autophagy, damaged organelles and aggregated proteins are engulfed within autophagosomes, subsequently delivered to the lysosome for degradation ,198. LocLysosomal function and protein degradation are regulated by many factors, such as lysosomal pH , calciumIn contrast, neurons expressing LRRK2-R1441C displayed a significantly increased lysosomal pH and alterations in lysosomal calcium dynamics, resulting in impaired autophagosome–lysosome fusion and decreased lysosome-mediated degradation c. These Over decades, research on PD pathogenesis has been dominated by a focus on mitochondrial bioenergetic defects, oxidative stress, and cell death mechanisms. With the discovery in 1997 that Lewy bodies are composed of misfolded/aggregated α-syn  and thatClearly, our understanding of the complex molecular mechanisms underlying PD pathogenesis and progression is still far from complete, and crucial questions remain to be answered. Among these, it remains to be clarified what event(s) initiate(s) PD pathogenesis, how Lewy bodies form, which of the intracellular functions of α-syn are actually relevant for disease onset and progression, and what role the microbiome plays in modulating PD, to name but a few.As research efforts in this field increasingly focus on interorganellar communication as opposed to single organelle biology , we expe


RB1, TP53, FBXW7, CTNNB1, and HNF1A pathogenic variants were identified, while in virus-negative cases only benign variants were found. In MCPyV-positive melanoma cases, besides BRAF mutations the following genes were also affected: PIK3CA, STK11, CDKN2A, SMAD4, and APC. In contrast to studies found in the literature, a higher tumor burden was detected in virus-associated MCC compared to MCPyV-negative cases. No association was identified between virus infection and tumor burden in melanoma samples. We concluded that analyzing the key morphologic and immunohistological features of MCC is critical to avoid confusion with other cutaneous malignancies. Molecular genetic investigations such as next-generation sequencing (NGS) enable molecular stratification, which may have future clinical impact.Merkel cell carcinoma (MCC) is a rare, high-grade, aggressive cutaneous neuroendocrine malignancy most commonly associated with sun-exposed areas of older individuals. A relatively newly identified human virus, the Merkel cell polyomavirus (MCPyV) has been implicated in the pathogenesis of MCC. Our study aimed to examine nine MCC cases and randomly selected 60 melanoma cases to identify MCPyV status and to elucidate genetic differences between virus-positive and -negative cases. Altogether, seven MCPyV-positive MCC samples and four melanoma samples were analyzed. In MCPyV-positive MCC  Merkel cell carcinoma (MCC) is a rare, high-grade, aggressive primary cutaneous neuroendocrine malignancy causing rapidly enlarging lesions on sun-exposed areas of older Caucasian individuals ,2. The iKIT, PIK3CA, and genes in the Hedgehog signal transduction pathway [NOTCH, RB1, and TP53 genes [A relatively newly identified human virus, the Merkel cell polyomavirus (MCPyV), has been implicated in the pathogenesis of MCCs . The vir pathway ,10,11. I pathway . MCPyV-n53 genes ,13. In g53 genes .BRAF mutation.Due to limited data available for molecular study in MCCs, particularly with next-generation sequencing (NGS) methods, the aim of our study was (1) to detect the MCPyV status of nine MCC patients, diagnosed from three separate institutes, (2) to compare the molecular differences between virus-positive and -negative subgroups, (3) to identify MCPyV frequency in other randomly selected cutaneous melanoma, and (4) to elucidate genetic differences between virus-associated and -negative cases and MCPyV-associated melanoma samples as well. For this purpose, histology examination, diagnostic IHC including antibody against large T antigen of MCPyV, MCPyV-specific PCR, and NGS with solid tumor gene panel analysis were performed using MCC and MCPyV-associated melanoma samples. Additionally, reverse-hybridization StripAssay was carried out on melanoma samples detecting Altogether, nine formaldehyde-fixed paraffin-embedded tissue (FFPE) MCCs and 60 control melanoma samples were tested. All protocols were approved by the authors’ respective Institutional Review Board for human subjects (IRB reference number: 60355/2016/EKU).Hematoxylin and eosin (H&E)-stained slides were carefully analyzed and validated by pathology specialists and appropriate tumor samples were selected for DNA isolation with a tumor percentage >20%. IHC of CK20 , synaptophysin , CHGA , and TTF-1  was performed to confirm MCC diagnosis. For the differential diagnosis in melanoma cases, S100 protein , vimentin , HMB45 , and Melan-A  antibody was used. MCPyV immunological detection was carried out using MCPyV large T-antigen antibody . Additional staining for Ki-67  was done to determine the cell proliferation index. The p53 antibody  was applied to compare immune positivity with molecular genetic findings in MCC cases.Genomic DNA was extracted from FFPE tissues using the QIAamp DNA FFPE Tissue Kit . The isolations were carried out according to the manufacturer’s standard protocol and the DNA was eluted in 50 µL elution buffer. The DNA concentration was measured in the Qubit dsDNA HS Assay Kit using a Qubit 4.0 Fluorometer .For virus T antigen and/or viral capsid DNA sequences in the nine MCC and 60 histopathological similar cutaneous malignant melanoma samples, LT1 (large T1), LT3 (large T3), and VP1  primer pairs were used. The DNA amplification was carried out according to the earlier study . To demoBRAF 600/601 StripAssay according to the manufacturer’s protocol . The assay covers nine clinically relevant mutations in the BRAF gene and is certified for human in vitro diagnostics (IVD). For interpretation, hybridization strips were aligned using the standardized layout supplied with the reagents, and positive bands were identified.Reverse hybridization was carried out using The amount of amplifiable DNA (ng) was calculated according to the Archer PreSeq DNA Calculator Assay Protocol . After the fragmentation of the genomic DNA, libraries were created by the Archer VariantPlex Solid Tumor Kit . The KAPA Universal Library Quantification Kit  was used for the final quantification of the libraries.The MiSeq System  was used for sequencing. The libraries  were denatured by adding 0.2 nM NaOH and diluted to 40 pM with hybridization buffer from Illumina . The final loading concentration was 8 pM libraries and 1% PhiX. Sequencing was conducted according to the MiSeq instruction manual. Captured libraries were sequenced in a multiplexed fashion with a paired-end run to obtain 2 ×150 bp reads with at least 250× depth of coverage. The trimmed fastq files were generated using MiSeq reporter .Raw sequence data were analyzed with Archer analysis software  for the presence of single-nucleotide variants (SNVs) as well as insertions and deletions (indels). For the alignment, the human reference genome GRCh37  was built. Molecular barcode (MBC) adapters were used to count unique molecules and characterize sequencer noise, revealing mutations below standard NGS-based detection thresholds. The sequence quality for each sample was assessed and the cutoff was set to 5% variant allele frequency (VAF). VAF is the percentage of sequence reads observed matching a specific DNA variant divided by the overall coverage at that locus. Large insertion/deletion (>50 bp) and complex structural changes could not be captured by the method. The results were described using the latest version of the Human Genome Variation Society nomenclature for either the nucleotide or protein level. Individual gene variants were cross-checked in the COSMIC  and ClinVar databases for clinical relevance. We used gnomAD v.2.1.1 population database to compare the significance of each gene alteration, which is included in our Archer NGS analysis system.The clinical features of the MCC patients are shown in The tumor cells of MCC show uniform, small, blue, round cells with high nuclear/ cytoplasmic ratio with granular chromatin and numerous nucleoli A. HistopMCPyV was detected with two methods. Five MCC samples were positive for the MCPyV antibody D. PCR amTwo types of agarose electrophoresis lane intensity were detected and high virus copy number samples were characterized with a robust band , while samples 4 and 8 showed weak stripe and, consequently, low virus copy number. The MCPyV LT3 and VP1 PCR results are presented in PCR amplification of LT1, LT3, and VP1 virus genes was carried out on 60 melanoma DNA samples. LT3 was present in four melanoma samples with a low copy number (6.7%), opposite to LT1 and VP1, where no PCR product was amplified.BRAF mutation status using StripAssay. Thirty BRAF mutations were identified. In 22 cases BRAF c.1799T>A; p. (36.7%) and in seven samples (11.7%) the c.1798_1799GT>AA; p. mutation was detected, while in one case (1.7%) the c.1799_1780TG>AA; p. aberration was present. LT3 amplification  was detected only in the BRAF+ group with Val600Lys amino acid change. The amplification result of the four MCPyV-positive melanoma cases is presented in The melanoma samples were analyzed for The 67 genes’ solid tumor panel analysis identified a series of alterations in the affected genes. The NGS analysis results are summarized in RB1 gene variant was identified in case 1 , VAF: 48%), while TP53 aberration was detected in case 3 , VAF: 92.4) and in case 9  correlation with p53 IHC positivity was detected. Additional pathogenic variants were determined in case 3 , VAF: 89.3%), in case 4 , VAF: 9%), and in case 6 , VAF: 7.5%), and a benign STK11 , VAF: 54.55%) variant was detected in case 2, a CDKN2A , VAF: 50%) variant was detected in case 5, and a JAK3 , VAF: 42.5%) variant was detected in case 8 was detected as well. In case 6 an ABL1 , VAF: 42.1%) and a FOXL2 , VAF: 65.3%) neutral aberration was identified. In MCPyV-negative case 7 no mutation was found.A BRAF-positive melanoma samples were analyzed using NGS (the fourth sample was not enough for NGS). Besides BRAF mutations , the following aberrations were found: PIK3CA c.1031T>C, p. and STK11 c.1211C>T, and p. in M1 melanoma case, CDKN2A c.169dup; p. and SMAD4 c.122A>G, p. in M2; and, finally, APC c.3949G>C; p. in M3 sample  was defined with the number of gene variants above 2% VAF . The larIn our study, we compared two methods to detect MCPyV in MCC and melanoma samples. The MCPyV monoclonal antibody, targeting the large T-antigen (clone CM2B4), effectiveness ranged from 39% to 90% . The senMCPyV-positive tumors have favored overall survival compared to MCPyV-negative MCCs, which also showed aggressive molecular mechanisms . After vKIT have not been identified in MCCs [PIK3CA mutations [RB1 and TP53 genes. The small T antigen is capable of stimulating cell proliferation through activation of several signal transduction pathways [RB1, TP53, and FBXW7 genes only in virus-positive MCC samples. Additional pathogenic variants were identified in CTNNB1 and HNF1A genes. In one study, the HNF1A gene mutation involvement of the virus-positive MCC pathogenesis was identified as well and, similar to our investigation, FGFR1, ABL1, and JAK3 variants were also demonstrated [EGFR, FOXL2, and STK11 genes in MCPyV-positive MCCs had not been identified earlier.Studies of molecular profiling on MCCs are scant and even controversial. Increased expression of the KIT receptor tyrosine kinase, in primary MCCs, demonstrated a shorter survival compared to patients with reduced levels of KIT in the malignant cells, although activating mutations in  in MCCs ,21. Otheutations , expressutations , aberratutations ,23. The pathways . Additiopathways . In our nstrated . AberratIn the literature, significant differences in the mutational burden that exists between MCPyV-positive and -negative cases were characterized, an order of magnitude higher for somatic single nucleotide variants per exome in virus-negative tumors compared to virus-positive cases . AnotherBRAF-mutant MCPyV-associated melanoma cases in our study subjects, which was discordant with earlier findings, where no virus-positive melanoma cases were found and, thus, the mutation status was not analyzed [We found four analyzed . In smalanalyzed . Additioanalyzed , non-melanalyzed ,33, and analyzed .BRAF, NRAS, and KIT. In our study, in the three virus-associated cases, besides BRAF mutation, PIK3CA, CDKN2A, and APC pathogenic variants were identified. Considering the genetic similarity between virus-associated MCC and MCPyV-positive melanoma samples, no significant differentiation was observed in the tumor burden, but the affected genes were different, owing to the randomly confused signal transduction pathways by the virus.Several studies dealt with genetic aberrations in melanoma using NGS ,36,37, aRB1, TP53, FBXW7, CTNNB1, and HNF1A pathogenic variants were identified, while in virus-negative cases only benign variants were found. In contrast to studies found in the literature, a higher tumor burden was detected in virus-associated MCC compared to MCPyV-negative cases. No association was identified between virus infection and tumor burden in melanoma samples. We concluded that analyzing the key morphologic and immunohistological features of MCC is critical to avoid confusion with other cutaneous malignancies. Molecular genetic investigations such as NGS enable molecular stratification, which may have future clinical impact.In conclusion, MCC is an aggressive cutaneous tumor that, although rare, is increasing in incidence. We used different methodologies to analyze the samples that could provide important information for potential therapeutic options and diagnostic approaches in the future. In MCPyV-positive MCC,


Diverse expression and activation regulation models endow NOXs/RBOHs powerful and versatile functions in plants to maintain innate immune homeostasis and development integrity. NOXs/RBOHs and their related regulatory items are the ideal targets for crop improvement in both yield and quality during agricultural practices.NADPH oxidases (NOXs), mostly known as respiratory burst oxidase homologs (RBOHs), are the key producers of reactive oxygen species (ROS) in plants. A lot of literature has addressed ROS signaling in plant development regulation and stress responses as well as on the enzyme’s structure, evolution, function, regulation and associated mechanisms, manifesting the role of NOXs/RBOHs as the vital performers and center hubs during plant growth and signaling. This review focuses on recent advances of NOXs/RBOHs on cell growth, hormone interaction, calcium signaling, abiotic stress responses, and immunity. Several primary particles, including Ca Moreover, salinity-induced Na+ accumulation in the cytosol triggers [Ca2+]cyt elevation, leading to activation of NOXs/RBOHs and apoplastic H2O2 accumulation cyt in root hairs of Arabidopsis, which is essential for polar growth [2+ binding to the EF-hand region and direct phosphorylation of AtrbohD synergistically activate its ROS producing activity [2+-regulated kinases, CDPKs become the focus for dissecting the activity and phosphorylation of NOXs/RBOHs. Increasing evidence shows that AtCDPK4, AtCDPK5, AtCDPK6 and AtCDPK11 are the positive regulators of AtRbohD under flg22 treatment [2+ and CDPKs may regulate the activity of NOX/RBOH respectively or synergistically.Studies performed on other plant species also demonstrate that Ca on Ca2+ . RbohC/Rr growth . In addiactivity . As the reatment . Among treatment . Similarreatment ,163,164.reatment ,166. The2+-regulated kinase represented by calcineurin B-like (CBL)-interacting protein kinases (CIPKs), which becomes activated upon interaction with CBL Ca2+ sensor proteins [2+. CBL10 and CIPK6 contribute to ROS generation by direct phosphorylation of NbRbohB during ETI [Arabidopsis, CIPK26 specifically interacts with the plasma membrane-localized Ca2+ sensors, CBL1 and CBL9, and they work together to phosphorylate the N-terminus of AtRbohF for ROS production [2+-dependent activation of the NOXs/RBOHs, and so NOX/RBOH phosphorylation is the initial trigger for the plant Ca2+-ROS signaling network [2+ and ROS signaling in plants, and Ca2+-binding and phosphorylation mediated by CDPK/CIPK synergistically activate the ROS-producing enzyme activity of NOXs/RBOHs in the Ca2+-regulated signaling pathway. In addition to CDPK/CPK, there is another Caproteins ,168. Recring ETI . In Araboduction . Moreoveoduction ,172,173.oduction , implyin network . These rReceptor-like kinases (RLKs) belong to a very large protein family with crucial roles in plant growth control, development regulation, cellular signal recognition and transduction. The typical RLKs include three major domains: an extracellular domain, a transmembrane domain, and an intracellular kinase domain; receptor-like cytoplasmic kinases (RLCKs) only possess a cytoplasmic kinase domain ,176. Intfls2 or efr mutants [Arabidopsis chitin-elicitor receptor kinase1 (CERK1), which is independent of BAK1 or related molecules [Arabidopsis, BAK1 serves as a co-receptor of FLS2 for flg22 recognition. BAK1 and FLS2 locate on plasma membrane in FLS2-BAK1 heterodimer form, which act as ‘molecular glue’ involved in immune signaling [It was reported that botrytis-induced kinase1 (BIK1), a protein of the RLCKVII subfamily member, can directly bind to multiple RLKs/PRRs in the resting state, such as flagellin sensing 2 (FLS2), elongation factor-Tu receptor (EFR) and PEP (Phosphoenolpyruvic acid) 1 receptor (PEPR1/2), which recognize a conserved 22 amino acid peptide of bacterial flagellin (flg22), a conserved N-terminal peptide sequence of the bacterial elongation factor-Tu (termed elf18 or elf26), and the endogenous AtPep1 (an endocrine peptide), respectively ,181,182. mutants , implyin mutants . Arabidoolecules , directlolecules . Actuallolecules ,187 but olecules . FER proolecules ,190. Thaignaling . FER alsignaling . RALFs, ignaling , whereasArabidopsis [bak1 or bik1 mutants in response to both flg22 and elf18 treatments [2+ burst prior to ROS production [In addition, increasing members of RLCKs, such as PBS1-like kinase (PBL1), brassinolide-signaling kinase 1 (BSK1), pattern triggered immunity compromised receptor-like cytoplasmic kinase (PCRK1) and botrytis induced kinase 1 (BIK1), were also identified as mediating the BAK1-dependent PTI signaling in bidopsis ,182,192.eatments . When fleatments ,194. To eatments . After teatments . PBL1, aeatments . BIK1 aneatments ,196. Besoduction ,197,198.As discussed above, the regulation imposed by BIK1 is a common regulatory mechanism for RbohD, in which BIK1 is the central immune regulator for multiple signaling from upstream to downstream to trigger an oxidative burst from NOXs/RBOHs . TherefoArabidopsis [Arabidopsis homolog of BIK1) was found to connect the chitin receptor complex CERK1-LYK5 and a MAPK cascade. PBL27 can phosphorylate and activate AtMAPKKK5 [The immune response is also mediated by CERK1 in conjunction with two OsCEBiP homologs, LYM1 and LYM3, which can directly bind to PGN , but do bidopsis . Howeverbidopsis . LYK5 isbidopsis ,209. CoitMAPKKK5 ,204. TheTwo RLCKs in rice, namely OsRLCK185 and OsRLCK176, the homologs of BIK1, can be directly phosphorylated by OsCERK1 during PGN- and/or chitin-induced immunity, and they may also participate in the activation of NOXs/RBOHs and triggering MAPK cascades ,210,211.Recruitment of regulatory receptor kinases seems to be specified by the type of PRR ectodomain. Accordingly, BAK1 is dispensable for chitin-triggered responses, whereas CERK1 does not participate in flg22-mediated signaling ,218. HowArabidopsis, it was reported that AtROP1, an OsRac1 homolog, plays an important role in AtRbohH/AtRbohJ-regulated pollen tube growth [Plants have a subfamily of Rho GTPases, which belongs to the Rat sarcoma (Ras) superfamily of small GTP-binding proteins and is called ROPs (Rho of plants) or RACs . The modules of ROP/RAC-NOX/RBOH mediate multiple extracellular signals ranging from hormones, pathogen elicitors and abiotic stresses, and regulate diverse cellular processes which are important for polarized cell growth, differentiation, development and reproduction  154,223223. For e growth . The ROP/RAC small GTPases serve as a two-state molecular switch depending on its GDP- or GTP-bound conformation . RecentlOnce activated, the GTP-bound ROP/RACs could recruit NOXs/RBOHs to mediate downstream ROS-dependent processes of plant growth and reproduction . In addiArabidopsis, two PRRs, OsCEBiP and OsCERK1, in which OsCEBiP acts as a receptor-like protein (RLP), directly binds to chitin. The two immune proteins could form a receptor complex to transduce the chitin signals to the downstream components upon fungal infection [Arabidopsis GEF, OsRacGEF1, which was identified as the specific GEF for OsRac1, mediates the change between the Rac-GDP inactive form and the Rac-GTP active form as a molecular switch [In rice, the most typical elicitor in RLK/GEF/RAC-mediated regulation of NOXs/RBOHs signal pathways during plant immunity is chitin. Chitin is one of the best characterized PAMPs in pathogenic and non-pathogenic fungi. Instead of FER in nfection ,213. Herr switch . OsRacGEr switch . Besidesr switch . OsRACK1r switch , and ther switch . The OsR2+ binding to the EF-hand motifs might be essential. It was reported that Ca2+ binding to the EF-hand motifs and phosphorylation by CDPK synergistically activate AtRbohD to produce ROS [2+-dependent manner, may sensitize NOXs/RBOHs for activation by phosphorylating their N-terminal region, thus inducing a conformational change and exposing the site for interaction with Rac GTPase [2+ flux has diphase change and plays a dual role in NOX/RBOH-mediated oxidative burst. In the initial stage of oxidative burst, cytosolic Ca2+ influx may be required by CDPK to phosphorylate NOXs/RBOHs and recruit Rac GTPases, both of which synergistically contribute to ROS burst. In turn, ROS and other components induce more Ca2+ influx, and the elevated Ca2+ in cytosol induces its efflux from the intracellular stores. When Ca2+ accumulation reaches a threshold, it may serve as a negative feedback mechanism to terminate the OsRac1–OsRbohB interaction and ROS production from OsRbohB [2+-dependent manner. Furthermore, the Ca2+-related negative feedback mechanism exerts an important function in regulating the RAC–NOX/RBOH interaction and maintaining the homeostasis of ROS in plants. Interestingly, a negative regulatory model was reported in vertebrates. In which, HACE1, a HECT domain and Ankyrin repeat domain containing E3 ubiquitin-protein ligase 1, directly targets Rac1 for degradation of the preformed signaling complex, and therefore negatively regulates Rac1-dependent NADPH oxidases in a ubiquitin-dependent manner [As mentioned above, phosphorylation plays important roles in activating NOXs/RBOHs and oxidative burst. However, the phosphorylation is not sufficient to fully activate NOXs/RBOHs . The conduce ROS . This prc GTPase . Moreove OsRbohB . These rt manner . WhetherArabidopsis and acts as upstream of NOXs/RBOHs to stimulate H2O2 production [rbohD mutant, suggesting that these MAPKs act as the upstream of RbohD-mediated oxidative burst in Arabidopsis [Nicotiana benthamiana [MAPK cascades are one of the most important and highly conserved signaling cascades, which consist of three tier components, MAPKKKs, MAPKKs and MAPKs, widely participating in plant growth and development, as well as in responses to a number of biotic and abiotic stresses ,245,246.oduction ,248,249.bidopsis ,251. Simthamiana  and maizthamiana . Coincidthamiana . In othethamiana ,206. In thamiana ,207. TheThere is now a substantial body of studies concerning hormones that participate in plant immunity and abiotic stress responses, such as ABA, JA, SA and ET. ,252,253.OST1 gene impairs ABA-triggered ROS production in guard cells, suggesting that OST1 acts upstream of NOX/RBOH in this signaling cascade [ost1 mutant of Arabidopsis [ABA has been the focus of intense investigation since it was identified in the 1960s as an endogenous small molecule growth inhibitor and regulator of plant stress physiology. It was reported that NOX/RBOH-dependent ROS production in guard cells plays an important role in ABA-mediated stomatal closure , and ABA cascade . In addibidopsis , and OSTbidopsis . In thisbidopsis . The OSTbidopsis . Considebidopsis , therebybidopsis .2O2 production, but also positively regulates NOX/RBOH [fer mutant can be partially rescued by the abi2-1 gain-of-function mutation.Besides OST1 and the associated components, a number of components in ABA signaling have also been characterized, including G proteins, protein kinases/phosphatases and receptors, involved in regulation of NOXs/RBOHs for ROS production. For example, ABA stimulates phospholipase D (PLD) activity probably through a putative ABA receptor. On ABA inhibition of stomatal opening, PLDa1 binds to GPA1 (α-subunit of heterotrimeric G protein) and regulates its function by promoting the conversion of GTP-bound Gα to a GDP-bound Gα, thus producing PA . SubsequNOX/RBOH . AnotherNOX/RBOH , implyinNOX/RBOH . As mentNOX/RBOH . On the NOX/RBOH . TherefoArabidopsis [Arabidopsis [Increasing evidences also reported that an ethylene receptor 1 (ETR1) and ethylene insensitive 2 (EIN2)-mediated signaling is required for the AtRbohD-dependent ROS accumulation during flagellin-induced intracellular response . AtPep1,bidopsis , plays abidopsis . Both ETbidopsis , can tribidopsis . It is t2O2 production through AtrbohD and AtrbohF in a coronatine-insensitive1 (COI1) depended way [2O2 levels in apoplast [ET not only potentiates the accumulation of ROS, but also together with the produced ROS, regulates stress-induced cell death . RbohF, nded way . COI1 isnded way . In addiapoplast . AlthougPsuedomonas syringae. At the same time, a L-type lectin receptor-like kinase (LecRKI.9) DORN1, the receptor of ATP, can directly phosphorylate NADPH oxidase RbohD, while mutation of DORN1 phosphorylation sites on RbohD eliminates the ability of ATP to induce stomatal closure [S-nitrosylated at Cys890 of the C-terminal portion by NO and S-nitrosylation could inhibit AtRbohD-dependent ROS production in response to Pst DC3000 expressing effector AvrB [Besides those common signaling particles mentioned above, there are also other various kinds of particles functioning in the regulation of NOXs/RBOHs activity. For instance, ATP-mediated stomata close is NOX-dependent. Addition of ATP leads to the rapid closure of leaf stomata and enhances resistance of plants to the bacterial pathogen,  closure . In addi closure ,259. Mor closure . It was  closure . Moreove closure . In vitrtor AvrB . Therefo2+-, CDPK-, BIK1-, Rac1- and/or SIK1-mediated signaling, became more and more clear. The high flexibility in NOXs/RBOHs regulation allows plant cells not only to prevent unintended signaling activation but also to modulate signaling amplitude and fine-tune immune responses, as well as to keep development integrity. However, numerous questions still remain to be answered in the future, for instance, the spatiotemporal dynamics of RAC-dependent activation, diphase Ca2+ flux change, the crosstalks between different signal pathways, the mechanisms of the messenger ROS transmit signals and NOX/RBOH-based ROS homeostasis and its exact meaning. In addition, increasing yield and improving quality are the foundations of agricultural development and the ultimate aim of scientific research. However, almost all of the results currently obtained are just on the basis of model plants, and only a few field crops have been considered for deep research. Therefore, new breakthroughs in NOX/RBOH research based on field crops such as wheat have become an urgent and charming expectation for sustainable agriculture. Currently, NADPH oxidases, being ROS producers, multiple signaling centers and diverse function implementers in plants, are becoming the focus of studies. Increasing members of them have been identified and reported. The highly conservative structure and complex evolution history endow them with stable functions donating ROS and versatile functions, involved in pollen gemination and root development, seed germination, fungal development, symbiosis between plants and microorganisms, stress response, etc. Over the past decade, several important regulation pathways addressing NOX/RBOH activity, such as Ca


Pseudomonas aeruginosa and reduced the organ injury in vivo. Together, these findings highlight that identifying the appropriate synergistic combination of mammalian cathelicidins with different beneficial properties may be an effective strategy against bacterial infection.Mammalian cathelicidins act as the potent microbicidal molecules for controlling bacterial infection, and are considered promising alternatives to traditional antibiotics. Their ability to modulate host immune responses, as well as their bactericidal activities, is essential for therapeutic interventions. In this study, we compared the bactericidal activities, antibiofilm activities and immune-modulatory properties of cathelicidins BMAP-27, BMAP-34, mCRAMP, and LL-37, and evaluated the therapeutic efficacy of the combination of BMAP-27 and LL-37 using a mouse pulmonary infection model. Our results showed that all of the four cathelicidins effectively killed bacteria via rapid induction of membrane permeabilization, and BMAP-27 exhibited the most excellent bactericidal activity against diverse bacterial pathogens. BMAP-27, mCRAMP, and LL-37 effectively inhibited biofilm formation, while BMAP-34, mCRAMP and LL-37 exerted immunomodulatory functions with varying degrees of efficacy by stimulating the chemotaxis of neutrophils, inducing the production of reactive oxygen species, and facilitating the formation of neutrophil extracellular traps. Of note, the combination of BMAP-27 and LL-37 effectively enhanced the clearance of  Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens  × 100.Hemolysis was performed by incubating a 4% (w/v) human red blood cell suspension in PBS (pH 7.4) with various concentrations (0–64 μM) of peptides for 1 h at 37 °C. Total hemolysis  and weak  [MIC values of peptides were determined by the twofold serial dilution method in 96-well flat-bottomed microtitration plates at a final concentration of 1 × 10d method . FIC wasto <1.0) ,47.P. aeruginosa ATCC 27853 cells were grown to the mid-logarithmic phase, washed with PBS three times, and diluted in the same buffer to 6 × 107 CFU/mL. Mouse infection was performed on the murine model described previously [6 CFU). One hour after bacterial exposure, 50 μL of 8 μM BMAP-27, 8 μM LL-37, the combination of 4 μM BMAP-27 and 4 μM LL-37, or PBS was instilled intratracheally into mice. To study the effectiveness of bacterial dissemination, mice were euthanized for 24 h after bacterial exposure, and their lungs were removed and homogenized. Homogenization or serial dilution of samples were placed on LB ager plates. The number of CFU was counted after incubation overnight at 37 °C and was expressed as CFU/g for lung tissues. In order to analyze the histopathologic changes of lung tissues, mice were euthanized 24 h after bacterial infection, and their lungs were quickly removed and fixed overnight in 4% paraformaldehyde solution. Then, the lungs were dehydrated, embedded in paraffin, sectioned at 4 μm, stained with hematoxylin and eosin, and microscopically examined for histopathologic changes.The animal experiments were carried out based on the protocol (HVRI-IACUC-2019-179) approved by the ethics committee of the Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences. eviously . Brieflyt-test or one-way analyses of variance. P-values less than 0.05 were considered to be statistically significant .Statistical analyses were performed using GraphPad Prism version 7.0 . Data were analyzed by performing Student’s


PTEN) is known as a tumor suppressor gene that is frequently mutated in numerous human cancers and inherited syndromes. PTEN functions as a negative regulator of PI3K/Akt signaling pathway by dephosphorylating phosphatidylinositol -trisphosphate (PIP3) to phosphatidylinositol -bisphosphate (PIP2), which leads to the inhibition of cell growth, proliferation, cell survival, and protein synthesis. PTEN contains a cysteine residue in the active site that can be oxidized by peroxides, forming an intramolecular disulfide bond between Cys124 and Cys71. Redox regulation of PTEN by reactive oxygen species (ROS) plays a crucial role in cellular signaling. Peroxiredoxins (Prxs) are a superfamily of peroxidase that catalyzes reduction of peroxides and maintains redox homeostasis. Mammalian Prxs have 6 isoforms (I-VI) and can scavenge cellular peroxides. It has been demonstrated that Prx I can preserve and promote the tumor-suppressive function of PTEN by preventing oxidation of PTEN under benign oxidative stress via direct interaction. Also, Prx II-deficient cells increased PTEN oxidation and insulin sensitivity. Furthermore, Prx III has been shown to protect PTEN from oxidation induced by 15s-HpETE and 12s-HpETE, these are potent inflammatory and pro-oxidant mediators. Understanding the tight connection between PTEN and Prxs is important for providing novel therapies. Herein, we summarized recent studies focusing on the relationship of Prxs and the redox regulation of PTEN.Phosphatase and tensin homolog deleted on chromosome 10 ( PIKAP) and a p110γ catalytic subunit [The phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) pathway is the critical intracellular signaling in controlling a variety of cellular processes . PI3Ks a subunit ,3,4. Tri subunit , which i subunit  and Akt  subunit ,8 and th subunit . Other k subunit .ROS are predominantly generated as by-products during various physiological processes and have both advantageous and disadvantageous effects in mammals . At low 2O2), which can oxidize and inactivate PTEN phosphatase activity, as mentioned by numerous studies [2O2. Prxs undergo modifications in their active site, especially the cysteine residues, which enables the protective function through protein-protein interactions, or subcellular protein targeting. The spotlight of this review is to show the connection between Prxs and redox regulation of PTEN.PTEN has an antagonizing function in the PI3K/Akt pathway by inhibiting the downstream signaling molecules via dephosphorylation of PIP3 to PIP2. Because PTEN possesses a cysteine in the phosphatase domain, it becomes a target of ROS, especially hydrogen peroxide , a phosphatase domain, a C2 domain, a carboxy-terminal tail domain, and a PDZ-binding motif [2+ chelating residues in vitro, which makes PTEN inhibit cell migration [362, Thr366, Ser370, Ser380, Thr382, Thr383, and Ser385 residues. There are some kinases inducing C-terminal domain phosphorylation: casein kinase 2 (CK2), GSK3β, LKB1, and MAST [ng motif ,26. The ng motif ,28. The ng motif . When cong motif ,30. Furtng motif ,30. The igration . The C-tigration . This doand MAST . When thand MAST . The PTEand MAST ,36,37.Several recent studies have demonstrated that PTEN has two isoforms: PTEN-Long (PTEN-L) and PTEN-β . The traIt is well-known that the major function of PTEN is a lipid phosphatase, and its main substrate is intracellular PIP3. PTEN exerts its role as a negative regulator of the proto-oncogenic PI3K/Akt pathway, which leads to the inhibition of the downstream signaling ,42. It h2O2 can induce PTEN oxidation, which inactivates PTEN phosphatase function by establishing a Cys124-Cys71 disulfide bond [tert-butyl hydroperoxide (t-BHP) have been shown as tumor promoters. When cells were stimulated with CuHP or t-BHP at various concentrations, PTEN was quickly oxidized and the disulfide bond was formed [2O2, CuHP and t-BHP induced irreversible PTEN oxidation, since the Trx was also targeted to oxidation and functional inhibition via dimerization [The PTEN phosphatase activity can be influenced by various factors, including PTEN post-translational modifications (PTMs) and PTEN-interacting proteins. It has been shown that several PTMs, including oxidation, S-nitrosylation, and acetylation, were found to regulate PTEN. PTEN is susceptible to oxidation since it harbors a cysteine residue at the catalytic site like other PTPs. This has been illustrated in various studies ,49,50,51ide bond . Howeveride bond . Some orrization .83 is S-nitrosylated [S-nitrosylation is also an important mechanism that affects the redox status of PTEN. Numerous studies have illustrated that nitric oxide (NO) is an agent inducing S-nitrosylation of PTEN, leading to the repression of both PTEN phosphatase function and the Akt downregulation . It has osylated . Recentlosylated . These d125 and Lys128 residues of PTEN are modified by acetyltransferase PCAF (or KAT2B) in response to growth factor stimulation [402 in the PDZ-binding motif. Acetylation of PTEN intervenes in the interaction between PTEN and its interacting proteins [Acetylation was also found to be one of the PTMs that control PTEN activity and function. Lysmulation , which lproteins . Moreoveproteins ,58. PTENPTEN phosphatase activity can be regulated by protein-protein interactions, which affects its stability, subcellular localization, and affinity. Several studies have shown that PIP3-dependent Rac exchanger 2 protein (PREX2) , shank-i2O2, organic hydroperoxides, and peroxynitrite since they possess thiol residues in their active sites [2-terminal site of Prxs, it has a conserved peroxidatic cysteine residue (CP) that is easily oxidized by peroxides [R), is located at the COOH-terminal site of the molecules. Based on the presence or location of the CR residue, members of Prxs are divided into three groups: 2-Cys proteins, atypical 2-Cys proteins, and 1-Cys proteins [2O2, whereas Prx V is more effective against alkyl hydroperoxides and peroxynitrite compared to H2O2 and Prx VI is more active against alkyl hydroperoxides over other peroxides [2O2-reducing activity that can control the levels of intracellular H2O2 [Peroxiredoxins (Prxs) are members of the small peroxidase family (22–27 kDa), which participate in the reduction of Hve sites ,64,65,66ve sites , its scave sites ,68. At teroxides ,70. The proteins . There aeroxides ,72,73. Dlar H2O2 .2O2, the CP-SH residue was transformed to cysteine sulfenic acid (CP-SOH). In the case of the 2-Cys Prxs, this unstable sulfenic acid forms an intermolecular disulfide bond with a CR-SH residue of the other molecule in the dimeric Prx structure. This disulfide bond is then reduced by the Trx system, which is firstly identified in yeast Prx (TSA) [52 and Cys173 [P or CR thus do not manifest Trx-dependent peroxidase activity [P-SH (Cys47 for both human isoforms) into CP-SOH. In the case of Prx V, an intra-subunit disulfide bond forms between CP-SOH with Cys151 (CR-SH), and this disulfide bond is reduced by Trx [R, thus, Prx VI CP-SOH cannot be resolved within the dimer. A cysteine thiol (CR-SH) of the π isoform of glutathione S-transferase (πGST) was found to resolve the Prx VI–SOH [47-SOH that was steadied by other surrounding residues [Prxs exist in a head-to-tail dimeric structure. During the reaction with Hrx (TSA) ,76 when d Cys173 . Mutant activity . Prx V ad by Trx . Prx V dd by Trx ,79,80, wd by Trx . Prx VI x VI–SOH ,82,83. Tx VI–SOH ,82,83. Oresidues . Like Pr2O2, the sulfenic acid (CP-SOH) was formed at the site of Cys51 after CP-SH oxidation. The intermolecular disulfide bond is formed after interacting with Cys172 of the other molecule in the Prx I dimeric structure. Eventually, this disulfide bond is reduced by Trx [2O2, a further oxidative reaction occurs that leads to oxidation of CP-SOH into CP-SO2H (sulfinic acid), subsequently inactivating its peroxidase activity. This sulfinic acid can undergo the reduction into thiol by Sulfiredoxin (Srx) system [P-SO2H to CPSO3H (sulfonic acid) is irreversible, which degrades Prx [Prx I belongs to the 2-Cys Prx group, therefore, when exposed to low levels of Hd by Trx ,76. Upon) system ,86, wherades Prx . These rades Prx . Accompaades Prx ,89.194 in vitro upon stimulation of various receptors  in several cell lines as well as in vivo following cutaneous injury in mice, thus contribute to remaining Nox-generated H2O2 levels for intracellular messenger function [2O2 reduction, which suggests potential therapeutic targets can be developed for the increase of acetylated Prx, including HDAC6 inhibitor [51 and Cys172), which leads to the inactivation of Prx peroxidase activity [The Prx peroxidase activity is regulated by numerous PTMs, such as phosphorylation, deacetylation, and S-nitrosylation ,91,92. Ifunction . Further2O2 (25 µM), the PTEN lipid phosphatase activity was completely protected by Prx I in cells, as the interaction between Prx I and PTEN was found. On the other hand, at high levels of H2O2 (500 μM), the hyperoxidation forms of Prx I can be observed with the dissociation from PTEN. As a result, at the 1:1 ratio of Prx I and PTEN, the high concentrations of H2O2 can oxidize Prx I at Cys51 and promote unwinding of the PTEN-binding conformation of Prx I consequently inducing their dissociation [It has been demonstrated that, under mild oxidative stress, PTEN tumor-suppressive activity was protected by Prx I via forming the intermolecular disulfide bond . At the ociation . In addiociation . Mutatioociation .2O2 for various times resulted in the formation of hyperoxidized Prxs. In Hela cells untreated with H2O2, the Prx I dimeric forms were predominantly observed since Prxs are considered as dimers in the absence of NEM [2O2-induced Prx I hyperoxidation, and the transient hyperoxidation-induced suppression of Prx weakened H2O2-scavenging activity [Exposure to He of NEM . The Prxactivity .2O2-induced oxidation.ROS has been demonstrated to participate in insulin signaling ,96. The 2O2, with half-maximal activity <20 µm [Prxs are well-known as peroxide-scavenging enzymes having a high affinity for Hy <20 µm . Also, Py <20 µm ,101,102.−/− compared to in Wild type (WT) at 5 min [−/− increased over time compared to that in WT MEFs. ROS levels were also increased in Prx II−/− MEFs after exposure to insulin [2O2 in intracellular signaling by targeting PTEN and Prx II, and the regulation of H2O2 concentration by Prx II are depicted schematically in It has been demonstrated that in the Prx II-deficient MEFs treated with insulin, the downstream signaling of the PI3K/Akt pathway increased, which was accompanied by an increase in oxidized PTEN levels and ROS levels . After iat 5 min . In addi insulin . The parLipoxygenases (LOX) are enzymes that catalyze the formation of hydroperoxyl-eicosatetraenoic acid (HpETE) from arachidonic acid (AA) and linoleic acid (LA), which could be important components in inflammatory and prooxidant mediators ,105. 15-124 and Cys71 was observed in both H2O2- and 15s-HpETE-treated MEFs [−/− MEFs compared to 5 min in Prx III+/+ MEFs [In MEFs, it was shown that both 15s-HpETE and 12s-HpETE induce the oxidation of PTEN and that oxidized PTEN was gradually reversed to the reduced form by cellular antioxidants after 30 min of exposure . Similarted MEFs . Moreove+/+ MEFs . These d+/+ MEFs , which iPTEN is well-known for the negative regulatory function of the PI3K/Akt pathway by dephosphorylating PIP3 to PIP2. However, ROS, which can be produced as a secondary messenger of intracellular signaling, has the ability to induce PTEN oxidation, forming an intramolecular disulfide bond and inactivating PTEN phosphatase function. In the cells, Prxs, the scavengers for peroxides, plays a crucial role in the redox regulation of PTEN and maintaining redox homeostasis. The redox regulation of PTEN by Prxs has been recently investigated in some contexts. The main focus of this review is on the redox regulation of PTEN concerning Prxs.2O2, Prx I was hyperoxidized and dissociated from PTEN. Besides, Prx II-deficient MEFs induced PTEN oxidation and increased PI3K/Akt activation when exposed to insulin, which leads to an increase the insulin sensitivity. Additionally, the deficiency of Prx II in Hela cells increased the PIP3 accumulation and Akt activation following the stimulation of growth factors [Prx I has been proved to preserve PTEN under mild oxidative stress by directly interacting with PTEN. However, under the high concentrations of H factors . Growth  factors . Therefo factors ,114. Fur


The main role of the human immune system is to eliminate cells presenting foreign antigens and abnormal patterns, while maintaining self-tolerance. However, when facing highly variable pathogens or antigens very similar to self-antigens, this system can fail in completely eliminating the anomalies, leading to the establishment of chronic pathologies. Prototypical examples of immune system defeat are cancer and Human Immunodeficiency Virus-1 (HIV-1) infection. In both conditions, the immune system is persistently exposed to antigens leading to systemic inflammation, lack of generation of long-term memory and exhaustion of effector cells. This triggers a negative feedback loop where effector cells are unable to resolve the pathology and cannot be replaced due to the lack of a pool of undifferentiated, self-renewing memory T cells. In addition, in an attempt to reduce tissue damage due to chronic inflammation, antigen presenting cells and myeloid components of the immune system activate systemic regulatory and tolerogenic programs. Beside these homologies shared between cancer and HIV-1 infection, the immune system can be shaped differently depending on the type and distribution of the eliciting antigens with ultimate consequences at the phenotypic and functional level of immune exhaustion. T cell differentiation, functionality, cytotoxic potential and proliferation reserve, immune-cell polarization, upregulation of negative regulators (immune checkpoint molecules) are indeed directly linked to the quantitative and qualitative differences in priming and recalling conditions. Better understanding of distinct mechanisms and functional consequences underlying disease-specific immune cell dysfunction will contribute to further improve and personalize immunotherapy. In the present review, we describe relevant players of immune cell exhaustion in cancer and HIV-1 infection, and enumerate the best-defined hallmarks of T cell dysfunction. Moreover, we highlight shared and divergent aspects of T cell exhaustion and T cell activation to the best of current knowledge. The primary function of the human immune system is to protect the host by reacting upon the encounter of foreign antigens, as well as to prevent autoimmunity through self-recognition. Two arms orchestrate the activation of the immune system: the innate response triggered within the first hours and the adaptive response mounted over the following days, able to recognize and target specific antigens and to generate memory. T cells are the major component of the adaptive immune system consisting of CD4 and CD8 T cells , being tvia the provision of processed antigens in the form of peptide/MHC complexes  and other important signals, including costimulatory interactions  and inflammatory cytokines  , in secondary lymphoid organs . Such prnal III) . Once acnal III) . After Cnal III) , but recnal III) . Memory nal III) , 9.Any disturbance of conventional activation signals may drive T lymphocytes to alternative cell fates, i.e., anergy, tolerance and exhaustion. This plasticity has evolved to constrain autoimmunity and excessive immune responses that would otherwise cause undesired tissue damage and immune-pathological conditions. Whereas, anergy is established during priming, due to the absence of costimulatory signals, and senescence is defined as growth arrest after extensive proliferation, exhausted T cells arise from cells which initially gained effector functions but became gradually dysfunctional due to continuous TCR stimulation by persistent antigens . OverlapT cell exhaustion was initially described in the mouse model of LCMV infection –16, wherper se, T cell dysfunction   and co-inhibitory receptors . In conclusion, persistent activation and induction of TOX are common drivers of T cell exhaustion in both viral infection and tumor pathogenesis. However, specific players such as CD4 T cell loss and TME heterogeneity in infection and cancer, respectively, contribute to define distinct and overlapping traits of exhausted T cells in the two conditions.Recently, terminally exhausted CD8 T cells have been characterized and distinguished from their progenitors depending upon the expression of PD-1, TIM-3, CD44, Eomes, T-bet, TCF-1, Slamf6, and CXCR5 , 128–134/TIM-3+) . Their p/TIM-3+)  and non-/TIM-3+) . Interesammation , 136–143operties . In additor pool , 145, thtor pool , 146–149tor pool , 144. Thse PTPN2 , 150–152se PTPN2 . TOX indMany studies have indicated HIV-1-induced T cell exhaustion as main hallmark of the disease. Of note, HIV-1-specific CD8 T cells selectively show features of exhaustion as compared to bulk CD8 T cell populations and unrelated virus-specific T cells circulating in the same subject, as described in human and animal studies –155.A complex network of stimulatory and inhibitory surface molecules orchestrates the functionality of CD8 T cells , 157. A In vivo, PD-1high SIV-specific CD8 T cells are characterized by a higher turnover  as opposed to the CXCR5− counterpart  are blocked  (Tox expression (Tcf7 (encoding TCF-1) promotes the generation of exhaustion precursors through the induction of Eomes and c-Myb in early chronic infection, whereas PD-1 is needed to stabilize this pool   –91, NOTCPrdm1) , NFATc1 Prdm1) , basic lPrdm1) –99, IRF-Prdm1) , 192–198pression  and indupression , NFATc-1pression , IRF-4 apression , at the his pool , 199. IRhis pool . Importanfection . Howeverand 2B4) , 201. Inand 2B4) , favorinand 2B4) , 202, anand 2B4) , 99. BATand 2B4) , 204 andand 2B4) , 99. BLIand 2B4) .Ifng, Ccr7, Il7r, Nt5e, Tcf7, and Lef1 loci), while presenting open chromatin regions in loci that govern the expression of IC molecules , of ectoenzymes implicated in metabolic regulation , of chemokines and cytokines  and of TFs  (Pdcd1 locus become completely demethylated (hi HIV-1-specific CD8 T cells but not in donor-matched naive cells (PD-1−)  , has shof2, Tox) , 111. Thf2, Tox) , 208. Mothylated , while tthylated . In para (PD-1−) . Thus, i (PD-1−)  and HIV- (PD-1−) , PD-1 ex (PD-1−) .Exhaustion in chronic viral infections has been described in both mice and humans as the progressive decrease in the capacity of virus-specific CD8 T cells to secrete cytokines, proliferate and exert cytotoxicity , 210–213Consistently with the hierarchical loss of effector functions by exhausted T cells, Riley et al.  demonstrThe identification of exhausted T cells in the cancer setting was inspired by previous knowledge gained in chronic viral infections. In human melanoma metastasis, T cells sharing many features of the exhaustion signature identified in LCMV infection were found . However+CD8+ TILs inversely correlate with survival  are allowing a deeper examination of the molecular properties of dysfunctional T cells at the single cell level. These studies represent milestones for the comprehension of T cell biology in the context of complex TME, dominated by a high heterogeneity of cellular subsets. Recently, Bengsch et al.  HIV-1 specific CD8 T cells (highCD160high) are functionally impaired in HIV-1 infected patients , activation markers and cytokines/chemokines . On the t manner . Patientt manner . These f, has been recently described as precursors of terminally exhausted cells (PD1high/TCF-1−/TIM-3+) to be distinguished from memory precursors cells (PD1−/TCF-1+) on the basis of several epigenetic and transcriptional alterations such as higher expression of CXCR5 and Slamf6  are stably rewired and resistant to remodeling after PD-1 blockade  are allowing a deeper examination of the molecular properties of dysfunctional T cells at the single cell level. These studies represent milestones for the comprehension of T cell biology in the context of complex TME, dominated by a high heterogeneity of cellular subsets and in HIV-1 infection where current immunotherapy may not improve T cell responses , 115. ThSV and SB wrote the 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.