In this review, the authors propose a crosswise examination of cytarabine-related issues ranging from the spectrum of clinical activity and severe toxicities, through updated cellular pharmacology and drug formulations, to the genetic variants associated with drug-induced phenotypes. Cytarabine  in multiagent chemotherapy regimens is often used for leukemia or lymphoma treatments, as well as neoplastic meningitis. Chemotherapy regimens can induce a suboptimal clinical outcome in a fraction of patients. The individual variability in clinical response to Leukemia & Lymphoma treatments among patients appears to be associated with intracellular accumulation of Ara-CTP due to genetic variants related to metabolic enzymes. The review provides exhaustive information on the effects of Ara-C-based therapies, the adverse drug reaction will also be provided including bone pain, ocular toxicity , maculopapular rash, and occasional chest pain. Evidence for predicting the response to cytarabine-based treatments will be highlighted, pointing at their significant impact on the routine management of blood cancers.Cytarabine is a pyrimidine nucleoside analog, commonly used in multiagent chemotherapy regimens for the treatment of leukemia and lymphoma, as well as for neoplastic meningitis. Ara-C-based chemotherapy regimens can induce a suboptimal clinical outcome in a fraction of patients. Several studies suggest that the individual variability in clinical response to Leukemia & Lymphoma treatments among patients, underlying either Ara-C mechanism resistance or toxicity, appears to be associated with the intracellular accumulation and retention of Ara-CTP due to genetic variants related to metabolic enzymes. Herein, we reported (a) the latest Pharmacogenomics biomarkers associated with the response to cytarabine and (b) the new drug formulations with optimized pharmacokinetics. The purpose of this review is to provide readers with detailed and comprehensive information on the effects of Ara-C-based therapies, from biological to clinical practice, maintaining high the interest of both researcher and clinical hematologist. This review could help clinicians in predicting the response to cytarabine-based treatments. Cytarabine or Cytosine arabinoside (1-β-D-arabinofuranosylcytosine) is a deoxycytidine nucleoside analog renowned among the most effective antineoplastic agents in upfront and salvage programs for myeloid and lymphoid leukemias, as well as Hodgkin and Non-Hodgkin lymphomas ,3,4,5. DThe metabolism and mechanism of action of cytarabine are directly linked to the biotransformation of its physiological deoxyribonucleotide counterpart, the natural nucleoside deoxycytidine, including membrane transportation, intracellular activation, and interaction with cellular targets. Gene products involved in this process have been well characterized and include transporters of solute carriers (SLC) and ATP-binding cassette (ABC) families, activators such as deoxycytidine kinase (DCK), nucleoside diphosphate kinase (NDK), and ribonucleotide reductase, as well as the catabolyzers of cytidine deaminase (CDA) and 5-nucleotidases ,17.Genetic variants for cytarabine-metabolizing enzymes and carriers have been identified, and coding or regulatory polymorphisms have been proposed of functional significance and clinical relevance, so advocating properly devised trials to validate putative associations with phenotypes of toxicity or chemo-resistance . SpecifiIn this article, the authors propose a crosswise examination of cytarabine-related issues, ranging from the spectrum of clinical activity and severe toxicities, through updated cellular pharmacology and drug formulations, to the genetic variants associated with drug-induced phenotypes. The goal of this review is to give readers an all-round information on the effects of Ara-C based therapies, from biology to clinical practice. This issue could help oncologist to plan optimal dosage and combination with other drugs to make a personalized treatment.The selective action against rapidly dividing cells and the lack of metabolic activation in solid tumors have ensued from broad activity, and focusing the application of hematological malignancies . The curSince 1974, cytarabine is used either alone or in combination with an anthracycline (daunorubicin or idarubicin) in virtually all induction regimens for acute myeloid leukemia (AML), and as a component of consolidation and maintenance programs after remission is attained .2/d for 5 to 7 days, other high-dose and low-dose schedules have been used for treating leukemia. The clinical activity of low-dose cytarabine in AML has been evaluated particularly in older patients or with preexistent myelodysplasia [2/d for up to 3 weeks, with the expectation that low doses would produce less toxicity and promote leukemic cell differentiation (or apoptosis). In general, though the low-dose regimens produce less toxicity, in terms of myelosuppression, than previously hydroxyurea-based treatments [The incorporation of cytarabine is needed also in AML subtypes with exquisite susceptibility to anthracycline treatment, such as acute promyelocytic leukemia . As a reysplasia ,29. Theseatments .2 every 12 h for up to six doses, was introduced about three decades ago, and, after the landmark CALGB study published in 1994, it became central to the improvement in the treatment of patients with AML [The high-dose schemes, usually 2 to 3 g/mwith AML ,32. In Awith AML  and upfrwith AML . For thewith AML ,35.2 for each dose), so to increase the therapeutic index of the drug [Due to concern of severe side effects, some researchers have recently suggested a possible replacement of high-dose cytarabine with an equally effective less toxic regimen delivering intermediate dosing  demonstrates clinically meaningful improvement in remission rate and Overall Survivor (OS) vs LDAC alone (#NCT03069352) .Venetoclax is a BCL2 inhibitor, this new class of drugs promising a manageable safety in optimized schedules combined to antimetabolites.Beyond the use in myeloid leukemia, cytarabine had a wide and established use, especially through the high-dose regimen, in upfront therapy against very aggressive lymphoproliferative disorders, such as acute lymphocytic leukemia and Burkitt and Burkitt-like lymphomas ,54,55,56Notably, high-dose cytarabine has represented, in the last 20 years, a cornerstone of salvage programs for patients with recurrent Hodgkin and non-Hodgkin lymphoma, mostly in combination with platinating agents ,61,62,63The toxicity profile of cytarabine is highly dependent on the dose and schedule of administration. With a standard 7-day regimen, myelosuppression is dose-limiting. Leukopenia and thrombocytopenia have the raiders occurring between days 7 and 14 after drug administration, with cytopenia duration eventually influenced by the concomitant use of other cytotoxic agents or previous treatment with chemotherapy. Gastrointestinal toxicity usually manifests as a mild-to-moderate mucositis and diarrhea. Occasionally acute pancreatitis has been reported in patients receiving cytarabine as a continuous infusion and in patients treated with L-asparaginase ,73. The 2 with each dose), common major side effects include biphasic pancytopenia, central nervous system toxicity, skin eruptions, and hyperbilirubinemia in more than 10% of patients while infection may affect two thirds of patients contributing to a treatment-related mortality rate of approximately 5% [2 per cycle) and age higher than 50 years also increases the risk for cerebellar toxicity [With the administration of cytarabine at high doses . In some cases, patients referred excessive tearing, photophobia, burning ocular pain and blurred vision, and the ophthalmologic examination confirmed the presence of conjunctival injection, central punctate corneal opacities with subepithelial granular deposits, and decreased visual acuity, all treatment-limiting adverse effect of therapy. At molecular level, it has been suggested that the inhibition of corneal epithelial DNA synthesis due to drug dosage and time of drug exposure.Ocular toxicity has been observed with high-dose cytosine arabinoside ) [Due to its hydrophilic properties, cytarabine requires transport into the cells and subsequent intracellular metabolic activation through sequential phosphorylation up to the cytotoxic triphosphate active form, which is incorporated into DNA, as false precursor in place of deoxycytidine triphosphate. This results in inhibition of DNA polymerase, chain termination and stalling DNA and RNA synthesis with the consequent blockage of the cell cycle from Gy 2021)) ,90.The different phases of drug uptake, activation, and deactivation, are described in detail after wards and synoptically resumed in SLC29A1 and SCL29A2, respectively) [SLC28A3) [Cytarabine gains entry into cells primarily as a false substrate through specialized nucleoside transporter proteins of SLC family, the human equilibrative nucleoside transportershENT1 and hENT2 (encoded by the gene ctively) ,92,93,94SLC28A3) ,96,97,98SLC28A3) ,100.The integral drug uptake depends on the proper balance of the nucleoside transporters and drug efflux proteins presented on cellular membranes. Therefore, the drug accumulation may be substantially reduced when the expression of hENT1 transporter is deficient, or the activity of ABC drug efflux transporter proteins is elevated.Cytarabine influx into the cells is strongly correlated with the cell surface abundance of hENT1 transporters , so thatAt drug concentrations above 10 µmol/L, the pump-mediated transport process becomes saturated, so that further entry of cytarabine can takes place freely by passive diffusion ,108.de novo synthesis of 5′-mono-, di-, and triphosphate derivatives throughout the sequential action of deoxycytidine kinase (DCK), deoxycytidine monophosphate kinase (dCMK), and nucleoside diphosphate kinase (NDK) encoded by the NME1 gene [Once inside the cells, as shown in ME1 gene ,109. DeoME1 gene . PhosphoME1 gene . PhosphoME1 gene . This inME1 gene ,113. AftME1 gene .2, which is considerably lower than a standard high dose of 3 g/m2 cytarabine  [In vitro studies have revealed that the intracellular concentrations of cytarabine-triphosphate are higher in cytarabine sensitive cells than in resistant cells ,115. Theacology) .In addition to its activation to cytarabine triphosphate, cytarabine is converted intracellularly into minor metabolites such as cytarabine diphosphocholine, an analog of the physiologic lipid precursor cytidine diphosphocholine that may interfere in lecithin and sphingomyelins synthesis, and be responsible for neurological toxicities ,120.Biological activity of cytarabine depends not only on the intracellular concentrations of cytarabine triphosphate but also on the endogenous nucleotide pools of cytidine-triphosphate (CTP) and dCTP. Cytarabine-triphosphate competes with dCTP for incorporation into DNA and to a lesser extent, with CTP for incorporation into RNA. In particular, high levels of dCTP result in resistance to cytarabine due to competition with cytarabine triphosphate for incorporation into DNA. This mechanism may be attractive for combinational administration of others antimetabolites such as fludarabine and cladribine . Hence, Finally, the intracellular levels of dCTP are regulated by the activities of the cytidine triphosphate synthetase (CTPS), a key enzyme in pyrimidine biosynthesis catalyzing the conversion of uridine triphosphate to CTP, and also modified by ribonucleotide reductase (RR), an enzyme composed of a dimerized large (RRM1) and small (RRM2) subunits catalyzing the reduction in ribonucleotides to deoxyribonucleotides for DNA synthesis ,127. ActDue to the similarity with the natural precursors required for cellular homeostasis, cytarabine and its metabolites are suitable substrates for various cellular enzymes, which catalyze their conversion into related inactive derivatives. The route of cytarabine inactivation is included in So, DCK activating function is reversed by cytosolic enzymes belonging to the family of 5′-Nucleotidase (NT5), namely NT5C2 and NT5C3. Opposing dCK, these enzymes catalyze the dephosphorylation of the monophosphate intermediate back to cytarabine through removal of 5′ phosphate ,133.Also opposing the activation pathway are the two deaminase CDA and deoxycytidine monophosphate deaminase (dCMPD). Cytidine deaminase is a multi-subunit enzyme involved in the maintenance of the pyrimidine nucleotide pool within the cell and physiologically catalyzes the hydrolytic deamination of cytidine to uridine and deoxycytidine to deoxyuridine ,134. In The balance between enzymatic activation and deactivation determines the effective amount of drug converted into the active metabolite cytarabine-triphosphate. This enzymatic balance varies greatly among cell types and maturity. The kinase deaminase ratio averages 0.03 in human AML, whereas the enzyme activities are approximately equal in acute lymphoblastic leukemia and Burkitt lymphoma . IncreasStudying the pathways involved in the transport, activation, or degradation of cytarabine has allowed the identification of mechanisms of resistance. The foregoing considerations over cytarabine metabolism and transport makes it clear that a number of factors could negatively affect response to cytarabine through the reduction in intracellular levels of the cytotoxic triphosphate metabolite of cytarabine. The mechanisms that critically determines resistance to cytarabine appears to be related to a deficiency of cytarabine cellular uptake and retention, overexpression of enzymes inactivating cytarabine, increased cellular dCTP pools, and increased DNA repair. Synoptically, the mechanism of resistance within cytarabine pathway are resumed in SCL29A1, DCK, CDA, and NT5C2 , have been mapped using 14 CEPH pedigrees and found that gene expression is heritable . Expresswww.pacdb.org (accessed on 13 January 2021)) which provides a unique resource to the researchers [The results from these studies on cytarabine and from other LCL-based pharmacogenomics research, are contained within the Pharmacogenomics, And Cell database  may be selected instead.Hereafter, we run through studies addressing genetic variants, polymorphisms, enzyme activities and protein expression levels associated to cytarabine. These are also recapped in 2 of cytarabine, hENT1 is accounted for up to 80% of cytarabine inward transport though considerable interpatient variations have been observed [SLC29A1) coding region appears to be highly conserved and, at functional characterization, genetic variants do not contribute to inter-individual differences in response to nucleoside analog drugs [SLC29A1 from Japanese subjects; yet the functional significance of these variants remains to be defined [Cytarabine is typically hydrophilic and, unless given at high dose, requires nucleoside transporter proteins to uptake efficiently inside the cells. At conventional doses of 100–200 mg/mobserved . hENT1  translocation .Inter-temporal marks variability of hENT1 staining intensities was documented in the Reed–Sternberg cells of Hodgkin lymphoma using immunohistochemistry applied to frozen tissues . ImmunocIn a study conducted in 115 non-Hodgkin lymphoma patients, a relatively high frequency of hENT1 protein positivity  was found in malignant follicular center cells and in particular in Burkitt Lymphoma (63%), diffuse large B-cell lymphoma , and follicular lymphoma (40%) .SLC28A3 for hCNT3 as of clinical relevance [The application of GWA studies to samples from European AML adult patients identified the SNP (rs11140500) in elevance .ABCC10 (MRP7) in HEK293 cells reduced the accumulation of cytarabine [ABCC11 (MRP8) determined increased cellular efflux of phosphorylated cytarabine metabolites [Consistent with the process of an efflux pump and contributive to cytarabine drug resistance, the expression of the ABC transporter tarabine  while ABabolites .There is a substantial clinical evidence indicating that the efficiency of intracellular cytarabine concentration mediated by hENT1 membrane facilitating diffuser is related to clinical outcome .The cell surface abundance of nucleoside transporter sites is closely correlated to cytotoxicity of cytarabine , and a tThe reduction in hENT1 expression was a common mechanism for resistance to antimetabolite treatment ,176 and A study using a cytarabine resistant CCRF-CEM cell line reported that genetic mutations of hENT1 that alter mRNA splicing and protein translation provide mechanisms for resistance to drug treatment . AdditiohENT1 gene, (−706G>C). Some authors reported, anonymously, a statistically significant tendency towards higher mRNA levels in PBMCs from individuals heterozygous for this variant, as compared with wild-type carriers [There is no clear functional impact of the genetic variant in the promoter region of carriers . Others carriers . These lcarriers .Of significant practical implication is the fact that hENT1 is strongly inhibited by various receptor tyrosine kinase inhibitors, an interaction that could limit cytarabine use with targeted drugs ,180.SLC28A3 for hCNT3 was recently found to be associated with disease-free survival at multivariate analysis among 154 European AML adult patients on high-dose cytarabine [Several studies have shown that the nucleoside transporter hCNT3 is involved in cytarabine cytotoxicity and resistance ,97. The tarabine . HoweverABCC11 gene SNP (538G>A) has been suggested to be a clinical biomarker for prediction of chemotherapeutic efficacy in breast cancer [No significant gene polymorphisms have been associated with resistance to cytarabine for ABC transporters, though for t cancer  and SNP t cancer .ABCC11 (MRP8) mRNA has been demonstrated in AML blasts from 50 patients, together with a low probability of overall survival at 4 years for those with high expression of MRP8. The result was statistically significant at regression analysis and independent of the dosage of cytarabine delivered during antileukemic treatment [Recently, a differential expression of reatment .Among the kinases participating to the multistep activity that lead to phosphorylation of cytarabine up to its triphosphate active metabolite, DCK is the rate-limiting enzyme. It exerts highest activity during the S phase of the cell cycle and is strongly inhibited by the physiological dCTP substrate .DCK gene is fairly conserved in Caucasians, in contrast to African populations [DCK mRNA expression has been demonstrated [DCK expression could lead to increase intracellular cytarabine triphosphate resulting in increased cellular sensitivity. The activity and expression of DCK varies widely in normal and malignant cells; furthermore, there is a 50-fold variation in DCK mRNA expression in patient leukemic cells, a 35-fold variation in DCK mRNA in primary AML cells, a 36-fold change in liver tissue and a 150-fold change in human liver metastases of colorectal cancer origin [The gene coding for DCK and a mutated version found in cytarabine resistant cells have been cloned ,184. Theulations  where hinstrated . This mar origin .DCK gene have been evidenced: five regulatory mRNA expression SNPs  and three non-synonymous coding changes Ile24Val, Ala119Gly, and Pro122Ser [Several genetic variants in the ro122Ser .The second phosphorylating enzyme, CMPK, is found in more than a hundred-fold higher concentration than DCK. Its affinity for cytarabine-monophosphate is low but greater than the affinity for the competitive physiologic substrate deoxycytidine-monophosphate. Because of its relatively poor affinity for cytarabine-monophosphate, this enzyme could become rate limiting at low cytarabine-monophosphate concentrations . No majoThe third phosphorylating enzyme, NDK, appears not to be rate limiting because it is present in very high concentration . In totaDCK in blast cells predict shorter disease free survival, as well as overall survival in an AML population treated with cytarabine [DCK. Examination of LCLs from HapMap populations determined that SNPs within DCK resulted in altered enzyme kinetics, increased cytarabine triphosphate intracellular concentrations, higher basal levels of DCK, and increased sensitivity to cytarabine [DCK (positions _36113 and _35708) were also associated with DCK basal expression and cytarabine sensitivity in the HapMap cell lines and cytarabine triphosphate levels in leukemic cell samples from patients with AML, respectively [DCK), whereas cell-based models identified candidate SNPs associated with these phenotypes that could be potentially useful in clinical dosing algorithms.Clinical studies have shown that low intracellular concentrations of the chemotherapeutic cytarabine in leukemia cells predict poorer outcome to treatment ,187. Liktarabine . Ex vivotarabine ,163. Addectively ,163. ThuDCK 122Ser (rs6743726) reported as being 43 ± 4% of the wild type (WT) allele in vitro in DCK coding region [The two regulatory SNPs (−360C and −201C) have been in linkage disequilibrium, and have been associated with a more favorable 2 years disease free survival in 122 AML Asian patients, and this was explained by lower DCK mRNA expression leading to reduced transcriptional activation when compared with the −360C/−201C haplotype . These pg region . Some aug region ,191; anyg region .NDK gene promoter have been correlated with drug-induced toxicity, in Caucasian AML patients. No significant correlation between SNPs and disease-free survival or OS has been found, but significant correlation with low platelet count has been identified for the NDK promoter SNP-835 C/T (rs2302254). In addition, increased risk of neurotoxicity for the SNP-835 C/T for allele T/T has been identified also at multivariate analyses [In total, five SNPs within the analyses .Another family of ‘activators’ could be represented by RRM1 and RRM2 catalyzing the reduction in ribonucleotides to their corresponding deoxy-ribonucleotides. Diphosporilated cytarabine influence indirectly pharmacokinetics by inhibition of ribonucleotide reductase  enzymes that catalyze reactions which generate deoxynucleoside triphosphates required for DNA synthesis.Low levels of deoxycytidine triphosphate due to CTPS inhibition or inhibition of ribonucleotide reductase lead to Ara-C phosphorylation (by reducing feedback inhibition of DCK), as well as incorporation of Ara-CTP into DNA. Conversely, cytarabine-triphosphate exerts only a weak inhibition and this lack of feedback allows accumulation of the cytarabine nucleoside to a higher concentration .Inhibition of CTPS with cyclopentenyl cytosine has been shown to deplete CTP and dCTP pools and increased sensitivity to cytarabine in human T-cell lymphoblastic cell lines and myeloid leukemia cell lines ,193,194.Ribonucleotide reductase regulates dCTP and other deoxyribonucleotides levels inside the cells so that its activity is straightly associated to sensitivity or resistance to cytarabine. Inhibition of RR can culminate in the accumulation of cytarabine triphosphate . BiochemSNPs within the RRM1 and RRM2 genes were evaluated in the HapMap LCLs from CEU and YRI panels to find possible correlation with expression and cytarabine chemosensitivity. SNPs of expected importance were further evaluated in leukemic blasts from 276 AML patients. RRM1 SNP rs1042919 (which occurs in linkage disequilibrium with various other SNPs) and promoter SNP rs1561876 were related to intracellular cytarabine triphosphate levels, response after up front treatment, disease and overall survival .Consistent with previous studies showing that SNPs in RRM1 are associated with response or toxicity to gemcitabine-based chemotherapy in lung and breast cancer patients ,199; finAs regards CTPS, mutations have been identified within the coding region in cytarabine resistant strains of Chinese hamster ovary cells, but none of these mutations was identified in samples from 36 patients, with acute leukemia refractoriness or recurrence ,201. ThuCytarabine catabolism is performed through processes of deamination, involving CDA and CMPD enzymes, and dephosphorylation by NT5C family enzymes.The primary role in cytarabine degradation and detoxification is played by CDA.CDA gene  were associated to alterations in putative transcription factor binding sites and impacted CDA enzyme activity as assayed in peripheral blood mononuclear cells (PBMCs) of healthy individuals [CDA nucleotide variant 79A>C which leads to a non-synonymous amino acid substitution in exon 1 from a Lysine to a Glutamine (Lys27Gln) and results in decreased activity of CDA with a 30% reduction in the cytarabine deamination rate [CDA Gln variant has been subsequently assayed through an haplotype analysis in an ethnically diverse sample set [CDA*1A to CDA*2A, this latter constituted by a combination of variant alleles −451T, −92G, −31Del, and 79C (27Gln), having the least and the most severe toxicities, respectively  with a significant loss of activity in vitro assays .Functional genomics studies in NT5C2 have been identified over 41 SNPs by GWA studies on ethnically well-defined DNA. Poor mRNA expression was detected in the presence of C>T rs11598702 in NT5C2; in addition, this SNP occurred in linkage disequilibrium with rs1163238 and 11191612, two further SNPs located in 5′ UTR . The reaCDA*2A and *2B variants  [A study performed on native PBMCs from 100 healthy volunteers reported a cytarabine-induced toxicity of approximately 53% among individuals carrying two  alleles . The mostion-31) .CDA variant of clinical prognostic relevance among the 360 AML adult patients receiving cytarabine, was associated with risk for death >50% as compared with wild-type carriers and maintained independent prognostic value also in multivariate analysis [CDA enzyme deficiency may occur in poor metabolizers patients carrying homozygous CDA 79C allele as assessed by different studies . An incranalysis .CDA variants has been studied and no haplotype analysis has been performed.In both studies, only the influence of single The role of CMPD in the pathogenesis of toxicity of cytarabine, has been poorly defined differently from the congener analog gemcitabine whose enzymatic deamination activity is impaired in the presence of the SNP 172A>G (Asn58Asp) with consequent toxicity due to reduced clearance of monophosphorylated metabolites .Since monophosphorilated intermediate of cytarabine activation is reduced by cytosolic 5′-nucleotidases NT5C2 and NT5C3, the activity level of this enzyme may represent one of the factors affecting the clinical outcome of cytarabine therapy. Increased expression of NT5C2 has been correlated with resistance to cytarabine chemotherapy and to a lower survival rate in a hundred patients undergoing cytarabine chemotherapy .An increase in the NT5C2 has emerged as a mechanism of resistance to cytarabine. Patients with AML and low expression level of NT5C2 have a better overall survival after treatment with cytarabine than patients with high expression . NT5C2 iFurther evidences for the implication of NT5C2 in the cellular response to cytarabine came from the correlation between the formation of cytarabine triphosphate in blasts from patients with AML and their corresponding ratio of the expressions of DCK and NT5C2 . In a reERCC, also named XPD). In addition, other genes as ATM, RAD51, and BRCA1 are described to be involved in resistance to nucleosides analog [Pharmacogenomic studies in cancer cells have consistently shown increased activity of nuclear protein able to remove alien nucleotides from DNA . DNA Reps analog .Germline variation in DNA repair gene encoding XRCC1 codon Arg399Gln variants has been associated to decrease in risk of toxicity in cancer . In addiEven if the genes or enzymes pathways which control cytarabine mechanism are known, these may or may not explain variation in response. So, while this knowledge has guided the initial molecular assays, subsequently, with the high-density genotype data available for the HapMap samples the application of genome-wide genotyping and whole-genome sequencing have led to the discovery of genes out of pathway showing correlation with phenotypes of toxicity and response to cytarabine, and representing potential novel pharmacogenomics markers.GIT1 and SLC25A37) and cytarabine were validated in an additional panel of LCLs.Associations between the expression of two genes  in AML patients of multicenter AML02 trial.Recently, a GWA based study, involving 523 LCLs, identified several statistically significant SNPs in Mutated Colorectal Cancer (MCC) gene associated with cytarabine sensitivity. In particular, one of them the rs1203633 with AA genotype was linked with poorer OS  for some patients may actually ameliorate their outcome . For exaThis evaluation should also be performed to avoid unnecessary complexity in the stratification system, which is relevant for trial design, feasibility, and generalizability of the results.Adding a new stratification factor would be worthwhile only if this increased the separation between risk groups while decreasing the with ingroup heterogeneity in terms of outcome.Beyond the use of genetic make-up of patients to predict response to treatment, the progress in pharmacogenomics has brought in-depth knowledge of the mechanism of action of cytarabine and prompted the development of new compounds that could play independently of membrane transporters or kinases and are less susceptible to degradation. Therefore, while the demonstration of improved diagnostic prediction of the aforementioned genetic variants and their translation into clinical practice keep on pending and represent a still slow process, new formulations and cytotoxic analogues of cytarabine have shown promise in in vitro and animal models so prompting therapeutic clinical trials .Protection of cytarabine from fast degradation and elimination has been primarily investigated, with the aim to prolong exposure of cells to cytotoxic concentrations. Since cytarabine is an S-phase specific drug an extended exposure of the cell to the drug is critical to achieve maximum cytotoxic activity. After encapsulation into pharmaceutically acceptable carriers and derivatives, cytarabine cannot be deaminated and seems to exhibit better pharmacokinetic parameters. As a consequence, new nucleotides with modified base- and sugar-moiety, pronucleotides, chemo conjugated analogues and liposomal formulations are contender to replace cytarabine in clinical practice, and even broaden therapeutic indications.Conjugation of cytarabine to phospholipids, steroids or fatty acids can modify the pharmacokinetics of the drug ensuring easier transmembrane uptake, independent from diffusion facilitating systems, and lower sensitivity to deactivation by CDA ,239.Ela cytarabine and elainic-acid conjugated cytarabine, has shown to be able to bypass the effect of hENT inhibition on CCRF-CEM cell line and in patient samples . In precXRCC3, BRCA2, and RAD51 in AML [A recent phase II study has explored in AML patients safety and activity of sapacitabine, an analogue of cytarabine incorporating a cyano group capable of nucleophilic attack with consequent strand breaks once incorporated into DNA . Investi1 in AML .Phase II trial are now exploring sapacitabine activity in chronic lymphoid leukemia and cutaneous T-cell lymphomas .Phosphorylated cytarabine analogues have been developed in which the phosphate moiety has been chemically masked so to increase hydrophobicity and facilitate entrance of the compound into the cell. The phosphodiester derivative of cytarabine UA911 has been able to circumvent DCK deficiency  while anActivated metabolites of nucleoside analogs may also be conjugated to innovative polymeric nanogels. This formulation, beyond permitting oral administration due to its stability in the gastrointestinal tract, was capable of an efficient transport and intracellular delivery of active drug form and resulted in substantial tumor growth inhibition in drug-resistant tumor xenograft animal model .A liposomal sustained-release formulation for intrathecal administration of cytarabine is available for the treatment of lymphomatous meningitis; due to pharmacokinetic characteristics and half-life in CSF of 100–263 h protracted exposure to the drug may be achieved by cancer cells in liquor . HoweverThe co-encapsulation of two or more synergic antineoplastic agents in the same liposomal device, that could serve as a springboard to reduce the effective drug dose and consequently soothe side effects, represents an innovative option in cancer therapy already adopted for improving the activity of pyrimidine analogues . After pThe last decade has witnessed significant advances in genome-wide profiling technologies , thus opening up the possibilities for high-throughput profiling and measuring of various molecular targets including gene expression, genetic variations, and more recently, epigenetic variations. In the meantime, the launch of the Human Genome Project and other parallel large-scale projects such as the International HapMap Project ,259 and The use in covert resistant diseases and the worrying profile of toxicities, even life-threatening, have made cytarabine as one of the antineoplastic drugs most studied by pharmacogenetics and pharmacogenomics. Exploring drug transport and cellular metabolism as key determinants of pharmacokinetics and pharmacodynamics, as well as heterogeneity in response and toxicity profiles  has led The crosswise examination of cytarabine-related issues proposed in this article, ranging from the spectrum of clinical activity and severe toxicities, through updated cellular pharmacology and drug formulations, up to the genetic variants associated with drug-induced phenotypes, has tried to arouse and maintain the interest of both basic researchers and the clinical hematologists. The opportunity of soothing or overcoming the serious adverse events related to cytarabine-based therapies and the hope of predicting response and circumventing drug-resistance phenomena can hopefully rely on the future implementation of the methods for genotyping the variants influencing cytarabine biotransformation, but above all on transversal cognizance and mutual confrontation about current boundaries of clinical practice and the multiplicity of the biological and translational acquisitions. Probably, more restrictive criteria for patient selection as well as further extension of the investigation to diseases other than AML, especially lymphoma, could eventually open up new opportunities and indications. A halfway acquaintance about the contests in treating patients and the exciting outlooks of genetic analysis would hopefully enhance investigation in leukemia and lymphoma patients of pharmacogenomics assumptions in clinical trials on cytarabine-centered therapies. If we take into account that mostly it deals with orphan diseases with not much room for large and well-powered studies, a greater awareness and a mutual encounter between geneticists and hematologists, prior to the involvement of statisticians and industry, represent the privileged way to connect the future of pharmacogenomics and outcome in leukemia and lymphoma patients even.


Darier disease (DD) is an autosomal dominant genodermatosis belonging to the group of keratinization disorders that can affect epidermis, nails and mucous membranes, caused by a mutation in the ATP2A2 gene on chromosome 12q23-24.1, which has an important role in calcium signal transduction [We report a case of a 59-year-old woman with itching red-brown hyperkeratotic papules and plaques distributed on her left chest and left lumbar region, in blaschkoid distribution. The skin surrounding the lesions was normal . DermoscWe performed a punch biopsy, and histopathological examination revealed acanthosis with acantholysis and dyskeratosis in the basal and suprabasal epidermal layers with formation of corp ronds and grains . Based oDD is characterized by specific dermatologic findings such as symmetrical keratotic papules on the seborrheic regions. Papules typically coalesce in plaques, usually localized in seborrheic areas of the trunk, scalp, forehead and flexures. Lesions may fluctuate in severity and are often exacerbated by ultraviolet light, heat, occlusion or stress .Darier and White first described this disease independently in 1889; it is also known as keratosis follicularis. A localized manifestation of DD is a rare finding and was reported for the first time in 1906. This peculiar form is characterized by keratotic papules unilaterally distributed in streaks or whorls following Blaschko lines. It typically has a late onset and is aggravated by sunlight . In factOur patient represents a peculiar case of segmental type 1 manifestation of DD. Although the treatment consisted predominantly of topical therapy, the patient refused any kind of topical application because of her faith in homeopathy and the relapsing course of her disease.


For many years, the therapeutic advances in gynecological neoplasms have remained steady, however, in recent years, the application of the most modern “-omics” sciences has shed light on the pathogenesis and on neoplastic progression, with important implications in the introduction of targeted treatments that are more effective and less toxic ,2. Current emerging therapies for solid tumors include various immunotherapeutic approaches, like immune checkpoint inhibitors (ICIs) ,4 that hIn the cancer treatment context, T cells have always been considered to be primarily responsible for the beneficial effect of immunotherapy. In addition to T cells, natural killer (NK) cells are also now seen as a promising cancer immunotherapy tool due to their ability to kill malignant cells without toxicity towards healthy cells ,6.Unfortunately, the function of these effector cell types is often drastically altered in the tumor microenvironment and this event can contribute to tumor progression and metastasis.Among existing cancers, female malignancies represent one of bugbears in terms of diagnosis and clinical approach efficacy. Indeed, female tumors are often characterized by an immunosuppressive tumor environment able to resist not just immune system attack, but also classical anticancer drugs ,8. For tAmong the most promising approaches to activate therapeutic antitumour immunity is the blockade of programmed cell death protein 1 (PD-1) ,10. PD-1In the gynecological context, current and ongoing studies are trying to improve clinical responses through immunotherapy strategies combined or not with classic treatments. Indeed, atezolizumab can be used with Abraxane  for advanced triple-negative breast cancer when the tumor makes the PD-L1 protein . It can Pembrolizumab can also be used along with the targeted drug lenvatinib (Lenvima) in women with advanced endometrial cancers that are not MMR deficient (dMMR) or microsatellite instability high (MSI-H), typically after at least one other drug treatment has been tried. In addition, immunotherapy makes sense in cervical cancer—a virally induced tumor that should be highly angiogenic. Virus-induced cancers generally make good targets for immunotherapy because viral proteins are strong immune stimulants. Based on these preliminary data, the FDA granted an accelerated approval in June 2018 to pembrolizumab for the treatment of patients with advanced cervical cancer who have disease progression during or after chemotherapy, whose tumors express PD-L1 (combined positive score ≥ 1).In light of this, the scope of this Special Issue is to contribute to dissecting molecular and cellular immunological mechanisms involved in female malignancy progression and metastasis and to take stock of immunotherapy successes and failures in these tumors. This information will provide new insights crucial for the development of new immunotherapeutic strategies and for the improvement of combination strategies in patient-specific female cancer treatments.


Oryza sativa L., is a cultivated, inbreeding species that serves as the staple food for the largest number of people on earth. It has two strongly diverged varietal groups, Indica and Japonica, which result from a combination of natural and human selection. The genetic divergence of these groups reflects the underlying population structure of their wild ancestors, and suggests that a pre-breeding strategy designed to take advantage of existing genetic, geographic and ecological substructure may provide a rational approach to the utilization of crop wild ancestors in plant improvement. Here we describe the coordinated development of six introgression libraries (n = 63 to 81 lines per library) in both Indica (cv. IR64) and Japonica (cv. Cybonnet) backgrounds using three bio-geographically diverse wild donors representing the Oryza rufipogon Species Complex from China, Laos and Indonesia. The final libraries were genotyped using an Infinium 7K rice SNP array (C7AIR) and analyzed under greenhouse conditions for several simply inherited (Mendelian) traits. These six interspecific populations can be used as individual Chromosome Segment Substitution Line libraries and, when considered together, serve as a powerful genetic resource for systematic genetic dissection of agronomic, physiological and developmental traits in rice.Rice,  Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) for over 60 years  is the progenitor of O. sativa. It is found dispersed throughout a wide range of habitats across South, Southeast and Eastern Asia  libraries by systematically recombining distinct subpopulations of both wild and cultivated forms of rice.In rice, the ern Asia . Over thern Asia . An evalIndica (cv. IR64) and Japonica (cv. Cybonnet) backgrounds using three genetically and bio-geographically diverse ORSC donors from China, Laos and Indonesia. This coordinated set of CSSL libraries is the first of its kind; it will enable investigators to begin to systematically examine the impact of wild introgressions in two very different genetic backgrounds, to mix and match introgressions from the same or different wild donor genomes, and to compare and contrast the phenotypic impact of introgressions in homozygous or heterozygous combinations. These materials provide the basis for predicting whether some wild subpopulations combine more productively with Indica versus Japonica varieties and offer insights about the allelic series in diverse germplasm. Deeper understanding about which combinations of wild by elite parents are most likely to give rise to superior offspring will help provide a roadmap to design pre-breeding programs that enable rice breeders to make more efficient use of wild and exotic plant genetic resources.The objective of this study was to develop and make available a suite of wild × cultivated rice CSSLs to stimulate both scientific discovery and translation in breeding, while helping to bridge the gap between genebanks and crop improvement. We provide a resource that can be rigorously evaluated in diverse environments using advanced phenotyping technologies, genetically dissected and/or expanded through crossing and/or genome manipulation, and shared widely with researchers and breeders with a common interest in exploring the genetic potential of crop wild relatives. Toward this goal, we generated six introgression libraries in elite O. sativa (Indica and Japonica) backgrounds using three wild (ORSC) donor accessions. To help select wild donors for CSSL development, genetic relationships were examined among 286 ORSC accessions and 54 O. sativa varieties initially using 50 Simple Sequence Repeat (SSR) markers and subsequently using a set of 113,739 GBS SNPs  presence of a wild introgression in a target region, i.e., a region that contributed to the goal of providing coverage of the entire donor genome with independent, overlapping substituted segments, (2) minimum number of wild introgressions in non-target regions, contributing to the goal of creating a library consisting of a set of near isogenic lines, each carrying a single wild introgression in an RP genetic background and (3) recovery of a “lost introgression,” in cases where a heterozygous donor segment present in one generation was not recovered in the subsequent generation, requiring the retrieval of a line from an earlier generation. The breeding scheme is presented in 1. The target segment size was calculated in Microsoft Excel, whereas the number of donor and background segments, and the percent recurrent parent genome, were calculated using CSSL finder. The libraries were visualized using the CSSL finder or GGT (Marker-assisted selection (MAS) was carried out at every generation. Foreground selection was performed in the first three generations using 384 Oligo Pool Assays (OPAs) to establish sets of lines that covered the donor genome . Subsequr or GGT  software2. The taxa (samples) were divided into six groups, each representing one of the six CSSL populations. In each library, SNPs were called based on major vs. minor allele, where it was assumed that the minor allele was inherited from the wild donor parent. SNPs with ≥39% missing data or heterozygous calls, monomorphic SNPs, and singleton SNPs were removed from each dataset. Specific SNPs were removed when it was known that one of the parents could carry either the major or the minor allele at that variant due to heterogeneity of the parental accessions. In addition to genome-wide assays, all five parental accessions in addition to CSSLs that had red or red/brown pericarp were analyzed using functional InDel markers for Rc developed by Rd described by Ph and BH4 using primers described in Genomic DNA was extracted from leaf tissue from individual plants in each backcross generation using a modified CTAB protocol . As new Morphological variation for 16 traits was documented for donor accessions and RPs based on observations of two to five plants per accession. Parent plants were grown in 4 inch pots in the Guterman greenhouse at Cornell University  during summer 2015 and evaluated as described in 3 were written to calculate per-library and per-line statistics and to make figures of marker distribution and graphical genotypes. Percent donor genome, percent heterozygosity, and percent missingness were computed based on the total number of informative markers per library. To map QTL in the interspecific CSSL population, stepwise regression within IciMapping v4.0 software4 (RSTEP-LRT option) can be implemented as described in Custom R scriptsOryza (GSOR) center in Stuttgart, AR, United States5. As is standard practice, five seeds per genetic stock will be provided for researchers to amplify. For partially sterile and low-yielding CSSLs, seeds from sibling or progeny lines may be provided in lieu of the original CSSL seed. Seeds from genebank accessions of the three ORSC donors are available as follows: OrA (W1944) from the National Institute of Genetics, Japan; OrB (IRGC106148) and OrC (IRGC105567) from the International Rice Germplasm Collection in the Philippines.Seeds from the CSSLs and the RPs, IR64 and Cybonnet, are available from the Genetics Stocks-O. sativa control samples were examined using a rooted NJ dendrogram and a previously generated set of 113,739 GBS SNPs (Indica and Japonica elite varieties. They were (1) NIAS W1944 (hereafter referred to as OrA) from China, classified in the Institute of Genetics in Japan as O. rufipogon Griff.; (2) IRGC106148 (hereafter referred to as OrB) from Laos, identified as Oryza nivara Sharma and Shastry; and (3) IRGC105567 (hereafter referred to as OrC) from Indonesia, classified as O. rufipogon Griff  and IR64  were selected as the RP  in the Philippines and released in 1985. It is a semi-dwarf variety with high yield potential, short growth duration, enhanced resistance to diseases and insect pests and is well-known for its superior eating quality  these regions are common by state (cbs) and inferred to be common by descent (cbd) in the different cross combinations, thereby resulting in swaths of monomorphic SNPs; (2) sterility challenges led to irrecoverable introgressions, whereby target donor segments in one generation could not be propagated into future generations, resulting in an apparent lack of polymorphism in these regions in the final library dataset; and/or (3) heterogeneity in recurrent parent accessions used for crossing gave rise to polymorphic regions in final libraries that were difficult to attribute to either donor or recurrent parent and thus markers in these regions were dropped during SNP filtering . It is difficult to explicitly attribute marker gaps to cbd (hypothesis one) because the exact individuals used for crossing may not have been the same ones used for genotyping; however, given our current understanding of the genetic relationships between wild and cultivated rice subpopulations, we postulate that it is unlikely the gap on chromosome 4 shared between IR64 × OrA, IR64 × OrC, and Cybonnet × OrA libraries is a result of cbd. As an example of hypothesis two, we report efforts to maintain a line containing an introgression covering the region on chromosome 11 from 14 to 25.7 Mb in the Cybonnet × OrA population. The line was eventually lost due to sterility, and its absence from the final library led to apparent monomorphism in the genotyping dataset, explaining the marker gap in this region for that library . As for Depending on the specific donor segments carried by each of the CSSLs, wild characteristics are sometimes observed in the final lines. Classic domestication traits that help differentiate wild and cultivated rice include pericarp color, hull color, degree of seed shattering and flowering time. Some of these characteristics make the CSSLs difficult to grow and/or subject them to regulatory oversight, and thus knowing which lines carry “wild” traits is helpful in designing experiments to further evaluate the lines.Rc (Os07g0211500) and Rd (Os01g0633500) loci, located on rice chromosomes 7 and 1, respectively  will produce rice with white pericarp. All three donor accessions in these libraries had red pericarp and both RPs had white pericarp  allele at Rc. We next examined the Rd gene and found that Cybonnet carried the recessive  allele but IR64 had the dominant Rd allele. OrB and OrC both carried the dominant  allele at the Rd locus, but OrA was heterogeneous; some individuals carried the dominant allele and had red seeds, and others had brown seeds due to a recessive allele at Rd.Out of the total 434 CSSLs comprising the six introgression libraries, 16 had pericarp color typically associated with wild rice  ; 10 of tectively . Both Rcpericarp . PCR resRc and/or Rd genes, and indicates the pericarp color observed in the grain. Of the 16 CSSLs that carried pigmented pericarp, eight were from the Cyb × OrA library, and none were from the Cyb × OrC library. The lines were genotyped using the methods described above and the observed pericarp color was consistent with genetic predictions in the libraries derived from OrB and OrC in both the Cybonnet and the IR64 backgrounds. On the other hand, sequencing of the Rd gene in the CSSLs derived from OrA revealed two separate single nucleotide substitutions (mut#1 = A and mut#2 = G) in exon 2, each of which have previously been shown to render the gene non-functional  carrying the same donor allele at rd (with the two mutations) had white pericarp because they carried rc alleles from their respective RPs on chromosome 7  causing a frameshift that rendered the protein non-functional. This was somewhat unexpected, as a well known 18 bp loss-of-function deletion in exon 3 is more characteristic of japonica varieties , but did not have black hulls  would need only a single introgression carrying a functional copy of Bh4 to manifest the black hull phenotype, while a CSSL in the Cybonnet background (ph/bh4) would require an extended donor introgression covering both genes (∼8.8 Mb region). As summarized in Ph and BH4; however, these lines did not have black hulls, suggesting that none of them carried both genes. The paucity of markers in the region  is a member of the trihelix family of transcription factors and lies near the end of the long arm of chromosome 4, linked to the two major black hull loci described above (qSH1 is a BEL1-type homeobox-containing protein on chromosome 1 (OsShattering 1 (OsSh1) is a YABBY transcription factor that was originally mapped as an ortholog of the Shattering1 gene in sorghum  carried donor introgressions at SH4 but were not observed to be shattering, and between 3 and 6 lines from each of the six libraries carried introgressions at OsSh1 and/or qSH1 with no obvious effect on the phenotype  differs from Cybonnet (Japonica). Thus, despite the presence of donor introgressions at OsSh1/qSH3, qSH1 and SH4 in many of our shattering CSSLs, it is not surprising that these loci, alone, are not predictive of the phenotype. These results open the door to further research using these materials to gain a deeper understanding of the genetic determinants of seed shattering in rice.Seed shattering is the result of a developmentally programmed weakening or degradation of the abscission cell layer at the base of the grain where it attaches to the pedicel, and abscission layer formation is known to be regulated by multiple genes that control the timing and degree of seed shattering . Large v6 . Four of the lines derived from crosses with OrA, which itself had the earliest flowering of the three wild donors, and two lines each from the other Cybonnet libraries. Data on flowering time under long day conditions is not available for the IR64 libraries. Studies of flowering time in rice have demonstrated that a combination of large- and small-effect genes define the genetic architecture of the trait, and adaptation to a wide range of daylength and temperature regimes is mediated by complex gene × gene interactions in both wild and cultivated populations. To date, more than a dozen flowering time genes have been cloned and characterized (OGRO database)6  and nume6 .OsGI-Hd1-Hd3a  pathway, corresponds to the GI-CO-FT  pathway in Arabidopsis. Hd1 is a homolog of Arabidopsis CO and it promotes heading under short-day and represses it under long-day conditions , under short-day conditions, but inhibits Hd3a and RFT1 under long-day conditions  and Grain number, plant height and heading date 7 (Ghd7). Ehd1 is expressed only under short-days and it promotes flowering by inducing transcription of Hd3a and RFT1, functioning independently of Hd1  in several lines per population . Overall7 , Rd (MW310644 - MW310658), Rc (MW310659 - MW310674), Ph (MW310675 - MW310688).The genotypic datasets presented in this study can be found in NS, LA, HK, KA, SH, J-WK, ES, BM, S-NA, and GE contributed to the development of CSSL populations. NS, SH, GE, and HK phenotyped the plants. NS, KA, and SH genotyped the plants. YS and GD developed data management tools. VG and DW developed the CSSL Identifier R Shiny App. NS, DW, SH, GE, and SM analyzed the data and wrote the manuscript. SM conceptualized the project. All authors contributed to the article and approved the submitted version.HK is currently employed by the company LG Chemical, Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Lead bromide perovskite nanoparticles are fabricated in the water, which has been recognized previously as a severe source of damage to halide perovskite materials and devices. The perovskite nanoparticles exhibit a high photoluminescence quantum yield and excellent material stability. While the optoelectronic conversion efficiency of this family of intensively investigated materials has been persistently improved, there are several challenges standing in the way of their practical application. Although lead-derived toxicity is still a concern4, poor stability is the most urgent problem confronting the halide perovskite research community6. The manifestation of the poor stability includes the visible degradation of materials and devices exposed to room and high temperatures, illumination, oxidizing environments, and humidity10, which is rooted in the not strong mixed ionic and covalent chemical bonding of halide perovskites.The past decade has witnessed the dramatic development of hybrid lead halide perovskites as promising semiconductors for applications in high-performance solar cells, photodetectors, light-emitting diodes, etc10. Despite the progress to date, obtaining materials and devices with both an optimal optoelectronic performance and a long lifetime under working conditions remains challenging.To overcome the instability issue of halide perovskites, a few strategies have been developed, including A-site composition engineering, the addition of defect passivation or ion migration blocking layers, dimensional reduction to two-dimensional phases or nanoparticles, grain size engineering or fabrication of single-crystal materials11.Among the factors that cause degradation of perovskite materials and devices, humidity has been recognized as a severe and irreversible source of damage. To achieve high-performance optoelectronic devices, the amount of water involved in the material synthesis and exposed to perovskite active layers in devices has to be strictly controlled. This is, however, not the case in a recent publication, where Liu et al. fabricated the lead bromide perovskite nanoparticles that show excellent stability and high luminescence performance by deliberately introducing a large amount of water3) samples are reaction products of ammonium ion modified MAPbBr3 and water, and are composed of MAPbBr3 nanoparticles encapsulated in PbBr(OH) matrix  from escaping to the air or migrating among grains; second, it can passivate nonradiative defects on the perovskite surface  effectively; third, it will confine electron and hole states to enhance oscillator strength and intensity of optical transition; finally, it provides protection by isolating MAPbBr3 from sources of degradation, such as H2O/O2. Compared with the MAPbBr3 synthesized by the normal procedure, the fabricated samples exhibit a significantly enhanced photoluminescence quantum yield (PLQY) from about 2.5% to 71.54%. Meanwhile the PLQY of the samples decreases to only ~90% of its initial value after one-year storage in aqueous solution. The samples show good stability under humid, high-temperature, and illumination conditions.The fabricated methylamino lead bromide perovskite  encapsulation layers and the interface between them and halide perovskites to enable more efficient charge carrier injection, which may improve the performance of the materials and devices further.


Diabetes mellitus exists as a comorbidity with congestive heart failure (CHF). However, the exact molecular signaling mechanism linking CHF as the major form of mortality from diabetes remains unknown. Type 2 diabetic patients display abnormally high levels of metabolic products associated with gut dysbiosis. One such metabolite, trimethylamine N-oxide (TMAO), has been observed to be directly related with increased incidence of cardiovascular diseases (CVD) in human patients. TMAO a gut-liver metabolite, comes from the metabolic degenerative product trimethylamine (TMA) that is produced from gut microbial metabolism. Elevated levels of TMAO in diabetics and obese patients are observed to have a direct correlation with increased risk for major adverse cardiovascular events. The pro-atherogenic effect of TMAO is attributed to enhancing inflammatory pathways with cholesterol and bile acid dysregulation, promoting foam cell formation. Recent studies have revealed several potential therapeutic strategies for reducing TMAO levels and will be the central focus for the current review. However, few have focused on developing rational drug therapeutics and may be due to the gaps in knowledge for understanding the mechanism by which microbial TMA producing enzymes and hepatic flavin-containing monoxygenase (FMO) can work together in preventing elevation of TMAO levels. Therefore, it is critical to understand the advantages of developing a novel rational drug design strategy that manipulates FMO production of TMAO and TMA production by microbial enzymes. This review will focus on the inspection of FMO manipulation, as well as gut microbiota dysbiosis and its influence on metabolic disorders including cardiovascular disease and describe novel potential pharmacological therapeutic development. Heart disease is the leading cause of death in the United States today. Furthermore, diabetic patients are twice as likely to develop cardiovascular disease (CVD). Most recent reports on diabetes mellitus from the Center for Disease Control and Prevention estimate that 9.1% of the population in the United States of adults 18 years and older have been diagnosed, where type 2 diabetes (T2D) mellitus is being attributed to approximately 95% of these cases .In patients with diabetes mellitus, primarily T2D, atherosclerotic CVD predominates as the leading cause of mortality . CVD is Other comorbidities associated with T2D are hypertension, dyslipidemia, and renal insufficiency . FurtherAs T2D progresses, hyperinsulinemia, hyperglycemia, and oxidized LDL culminates in endothelial cell dysfunction and apoptosis . This deComplicating CVD in T2D patients is the common association of combined hyperlipidemia, a pro-atherogenic lipid disorder, characterized by high levels of LDL, triglycerides (TGs), and decreased levels of HDL . ImpropeCurrent pharmacological therapies for T2D, when in conjunction with CVD, attempt to reduce associated risks through tight glycemic control, dietary changes, and statin drugs. However, statistical evidence shows no significant correlation in lowering the risk of CVD with these treatments alone when considering T2D patients . Even whConversely, therapies that seek to lower LDL via clearance upon upregulation of LDL receptors have shown statistical significance in cardiovascular risk reduction . These fThis review will examine different metabolic pathways involved in dysbiosis and efforts to ameliorate the downstream physiological consequences. In addition to, an examination of how modulating enzymatic activity directly involved with formation of the biomarker trimethylamine N-oxide (TMAO) may improve health outcomes in patients with CVD and/or T2D.Recent research has intensified in the area of the gut microbiome and its implication in various disease pathologies exhibiting the significant role bacteria play in metabolic homeostasis . There eAlong with microbial induced inflammatory effects, degradation of the mucosal membrane leads to infiltration of the epithelial membrane by other endotoxins, pro-inflammatory cytokines, and potentially harmful bacterial metabolites . CrosstaMoreover, structural and functional intestinal alterations arising from a lack of diversity in the microbiome have shown a correlation with increased heart failure related risk and incidence . MarquesIn addition, there exists links between microbiota dysbiosis and vascular tone resulting in blood pressure regulation by regulating cardiac and renal early growth response 1 protein (Egr1) and the renin-angiotensin system . MarquesTrimethylamine N-oxide has been associated as an independent risk factor, aside from genetic predisposition and environmental factors, for CVD and atherosclerosis . Kamo etTrimethylamine N-oxide has been shown to induce endoplasmic reticulum (ER) stress through the elevation of ER-HSP70 isoform , and by Elevated levels of TMAO have also been observed to inhibit mitochondrial electron transport, thus leading to mitochondrial uncoupling and ROS formation in vascular endothelial cells . In addiTrimethylamine lyase is a bacterial enzyme that is known to cleave dietary choline during an anaerobic process releasing TMA and acetyl aldehyde in the process. Recent reports have built DMB analogs to inhibit TMA formation by inhibiting CutC/D lyase. Another study has shown that mechanistically DMB prevents the catalytic activity required from the substrate choline’s quaternary ammonium motif, thus providing a structure that can competitively bind but not exhibit reactivity, thus effectively inhibiting choline from being cleaved to TMA as illustrated in Trimethylamine lyase is also of important to consider, as strictly inhibiting FMO3, can lead to an increase in circulating TMA levels causing an unpleasant “fishy” smell in a condition that is known as Trimethylaminuria . To avoiOf the major oxidative drug metabolizing enzymes in the body the Cytochrome P-450 (CYP450) family exists as the most prominently expressed, existing in over fifty isoforms, class of enzymes for first step biotransformation of xenobiotic compounds . More reFunctional characterization of FMO3 is best understood when examining the polymorphisms that are commonly associated with the enzyme. Single nucleotide changes can have profound effects on the structure and function of FMO3, often leading to Trimethylaminuria . Genomic+ and FAD-OOH. TMA is located at the entrance for nucleophilic substrates to enter the enzymatic cycle and become oxygenated.Located on the endoplasmic reticulum, FMO’s can oxygenate a wide variety of soft nucleophilic xenobiotics such as heteroatoms containing nitrogen, sulfur, boronic acids, selenium, and phosphorous functional groups . FMO’s rin silico key structural features can be identified and mechanistic action can be better understood to further aid with drug design  as the main focal point at which substrate metabolism occurs. By mapping out the surrounding enzyme binding site g design . Crystalg design , bound tClinical trials using dietary indoles coming from Brussel sprouts have shown efficacy in lowering the relative ratio of TMAO to TMA through inhibition of FMO3. This research discovered that acid condensation products of dietary indoles that can be observed in In male diabetic Sprague-Dawley rat models treated with streptozotocin, increased FMO activity and was thus positively correlated with increasing blood glucose levels. However insulin treatment returned FMO activity to normal (non-diabetic) levels. Conversely, insulin treatment had no effect on FMO activity in non-diabetic rats . In regacDNA analysis of biopsied liver tissues from T2D patients have also shown that genes associated with stress defense such as FMO5 and superoxide dismutase 2 are down-regulated when compared to the non-diabetic patients . Thus, FFlavin-containing monooxygenase 3’s primary expression has been observed in the liver where it is the primary site for TMA metabolism to TMAO for the purpose of increased solubility and improved renal clearance as observed in 2+ efflux and vascular smooth muscle cell activation. Further these results also demonstrate the significance that TMAO has on propagating diseases through a variety of metabolic pathways (In patients with chronic kidney disease, elevated levels of TMAO contributed significantly to the development of renal fibrosis resulting in poor mortality outcomes . These rpathways .While FMO3 has garnered the most attention, other FMO enzymes demonstrate potential for therapeutic intervention as well. While FMO5 shows expression in the small intestines, kidneys, lungs, and liver  expressiEven though compounds such as DMB and dietary indoles have shown promise as a therapeutic intervention for CVD and T2D there is still much that can be improved upon in their chemical structures. DMB has only been shown to be effective as a non-lethal inhibitor of bacteria and inhibiting TMAO levels, however it has yet to be demonstrated that any improvements in glucose homeostasis or insulin sensitivity would be observed.Dietary indoles, while effective at inhibiting FMO3 activity and reducing TMAO levels,  have inhNo current therapeutics target both bacterial and human metabolism in a way that can reduce systemic inflammation, reorganize cholesterol levels, and improve energy regulation to reduce the effects of aging and dietary overload that is characteristic of patients with CVD and T2D. By combining these targets into one therapeutic, it might be possible to modulate crosstalk in the gut-liver-heart axis, effectively controlling the succeeding cascade of events that play out in rescuing further development of complications that arise in T2D and CVD.IS and NG drafted and finalized the manuscript with support from RA. RA provided the basis for the review and guidance throughout the manuscript development. MG, SY, and JZ involved in subject discussion, formation of material, and manuscript revision. 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.


Long non-coding RNAs (lncRNAs) have important regulatory functions across eukarya. It is now clear that many of these functions are related to gene expression regulation through their capacity to recruit epigenetic modifiers and establish chromatin interactions. Several lncRNAs have been recently shown to participate in modulating chromatin within the spatial organization of the genome in the three-dimensional space of the nucleus. The identification of lncRNA candidates is challenging, as it is their functional characterization. Conservation signatures of lncRNAs are different from those of protein-coding genes, making identifying lncRNAs under selection a difficult task, and the homology between lncRNAs may not be readily apparent. Here, we review the evidence for these higher-order genome organization functions of lncRNAs in animals and the evolutionary signatures they display. The three-dimensional (3D) organization of DNA in the cell nucleus has become a significant subject of study, particularly its influence on gene regulation. Recent advances in chromatin conformation capture (3C) techniques, computational, and modeling approaches have made its study feasible on a genome-wide scale, giving insight into the structure and the dynamics of chromatin folding in space and time. Nuclear 3D organization has multiple levels and varies between cell types and biological conditions. For instance, chromosomes are subdivided into topologically associating domains (TADs) within which chromatin loops bring together regulatory elements and target loci separated in the linear genome . These cIn addition to DNA and histones, RNA is a major component of the cell nucleus . High-thThere has been a long debate on whether most lncRNAs are functional or not . This diThe conservation signals in lncRNAs can differ from those typically found in protein-coding genes . For insin vivo across the genome  is highly conserved from human to zebrafish , encode transcription factors crucial for patterning along the anterior-posterior axis. Numerous ncRNAs are transcribed from the human HOX loci, and their expression relates to differential histone marks and transcriptional accessibility  lncRNA is transcribed from the boundary between domains with differential chromatin marks at the HOXC locus but acts in trans repressing transcription of coding and non-coding genes on the HOXD locus  located downstream of HOTAIR promotes transcription of the lncRNA. This loop is disrupted by the recruitment of hepatocyte nuclear factor 4-α (HNF4α), a master regulator of epithelial differentiation, to the HDE  present contradictory results. On the one hand, the deletion of the HoxC cluster, including mHotair, did not affect HoxD silencing in vivo , transcribed from the 5' end of the HOXA locus in mammals and conserved in avians  complex, driving H3K4me3 (HOTTIP and its association with CCCTC-binding factor (CTCF), which delineates active and inactive TADs within the HOXA cluster, also influence the expression of HoxA genes  is a lncRNA involved in pluripotency, hematopoiesis, and adipogenesis (Firre accumulates across a ~5 Mb domain around its transcription site on the X chromosome (Firre transcription (Firre with Heterogeneous Nuclear Ribonucleoprotein U (HNRNPU), through a 156-bp repeating RNA domain  are conserved to different extents across Firre orthologs in mammals. Firre is also required for the super-loop formation of the inactive X chromosome (Xi), H3K27me3 deposition, and the localization of the Xi to the perinuclear region , to direct the active priming of the promoters of immune genes, necessary for a rapid and robust pro-inflammatory response as part of trained immunity , engages in chromosomal contacts with CXCL chemokine genes belonging to the same TAD, but UMLILO does not have enhancer-RNA-like characteristics. In contrast to other IPLs, UMLILO is not conserved in mice and only partially conserved in pigs, suggesting that IPLs are not essential across species, but have a complementary role in ensuring robust gene expression. UMLILO has short conserved sequence motifs and interacts with WDR5 through its conserved exon 3, directing WDR5/MLL1 to chemokine gene promoters, mediating H3K4me3. Transcription of chemokines in UMLILO knockdown cells was restored by insertion of another WDR5-binding lncRNA, HOTTIP, under the control of the UMLILO promoter  locus. ESR1 is strongly upregulated in cancerous cells undergoing estrogen deprivation. A cluster of ncRNAs, ESR1 locus enhancing and activating non-coding RNAs (Eleanors), are transcribed from introns in a large chromatin cluster within a TAD that contains the ESR1 locus , induced repression of the rest of the Eleanors and the genes within the TAD, including ESR1  despite almost no sequence conservation outside an eight nucleotide-long conserved patch of microhomology (Examples of this conundrum are dosage compensation lncRNAs in nogaster . Detailenogaster . Importaensation . Furtherhomology .antisense to Igf2r RNA non-coding (Airn), required for paternal-specific silencing of imprinted genes in the insulin-like growth factor 2 (Igf2r) cluster , and this association is necessary for the insulator activity of CTCF in vivo (The non-coding isoform of the steroid receptor RNA activator (SRA), ervation . ncSRA ftructure . ncSRA a in vivo . The fun in vivo .X-inactive specific transcript (Xist), essential to the establishment of X chromosome inactivation, interacts with proteins such as the polycomb repressive complex 2  proteins. Domains outside these interaction zones are not conserved and lack structure (Dosage compensation lncRNAs (see next section) show patches of structural conservation of biological importance. The Repeat A (RepA) region of  2 PRC2; , ATRX ch 2 PRC2; , and SHA 2 PRC2; . RepA wafunction . lncRNAstructure .HOTAIR has also been shown to have a complex secondary structure, with some evidence of conservation in mammals acquired from computational methods  and is expressed exclusively from the inactivated X  found in marsupials, chicken, and fish suggests that Xist emerged through pseudogenization of Lnx3, possibly by the insertion of tandem repeats from transposable elements , which is transcribed from and coats the paternal chromosome (Xist and Rsx adds to the notion of dosage systems rapidly evolving from ancient silencing mechanisms common to all eukaryotes through the use of lncRNAs (Xist by non-coding elements located at its own and the neighboring TAD and the impact of this 3D conformation on the regulatory landscape adds another layer of complexity to the mechanisms for dosage compensation (Interestingly, in marsupials, X-chromosome inactivation is imprinted, tissue-specific, and somewhat incomplete compared to eutherians, and thought to be achieved by female-specific expression of the lncRNA romosome . The ind lncRNAs . The disensation .roX1 and roX2 lncRNAs mediate the upregulation of genes on the single male X chromosome to equalize expression of the two X chromosomes in females. roX1 and roX2 associate to the MSL proteins, forming the MSL complex that localizes to numerous specific sites along the male X (via spatial proximity from high-affinity sites – enriched at TAD boundaries – to other regions (Xist, whose activity is limited to the chromosome from which it is expressed (roX transgenes target the X chromosome in trans and rescue roX1 and roX2 mutant males (lncRNAs are also the effectors of dosage compensation in drosophilids, but they differ in both origin and mechanism to those in mammals. Here, the e male X , mediati regions . Contrarxpressed , roX trant males .Xist in mammals, Rsx in marsupials, and roX1 and roX2 in flies suggests that lncRNAs may be one of the fastest mechanisms to evolve novel epigenetic controls. As these lncRNAs participate in dosage compensation but have emerged independently in several lineages, they are extraordinarily difficult to identify as functionally convergent. Additional examples of functionally equivalent lncRNAs with no evolutionary relationship may likely have gone undetected.The independent origin of via modeling or direct RNA-seq evidence, followed by comparison across taxa (Distinctly, lncRNAs have emerged as an additional layer of complexity involved in shaping the three-dimensional organization of the genome by interacting and modifying the structure of chromatin. Several lncRNAs affect chromatin conformation and display a combination of conservation signals that may be difficult to identify solely by looking at traditional genomic conservation metrics (summarized in oss taxa . In the oss taxa . One of oss taxa , 2020.in silico studies with experimental approaches in the context of spatiotemporal gene expression programs is crucial to further assess the impact of these ncRNAs on modulating genome architecture, including their specific contribution to the complexity and evolution of animal gene regulation.In the context of studying novel lncRNAs, its unique conservation signatures, albeit more difficult to detect, are excellent ways to identify potentially functional lncRNA candidates and give a first insight on their possible mechanisms of action. They can also help guide the search for homologous mechanisms in other species. Complementing All authors participated in writing and reviewing the manuscript and approved the final version for publication.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.


Mammalian, or mechanic, target of rapamycin (mTOR) signaling is a crucial factor in the regulation of the energy balance that functions as an energy sensor in the body. The present review explores how the mTOR/S6k intracellular pathway is involved in modulating the production of different signals such as ghrelin and nesfatin-1 in the gastrointestinal tract to regulate food intake and body weight. The role of gastric mTOR signaling in different physiological processes was studied in depth through different genetic models that allow the modulation of mTOR signaling in the stomach and specifically in gastric X/A type cells. It has been described that mTOR signaling in X/A-like gastric cells has a relevant role in the regulation of glucose and lipid homeostasis due to its interaction with different organs such as liver and adipose tissue. These findings highlight possible therapeutic strategies, with the gut–brain axis being one of the most promising targets in the treatment of obesity. In 1964, rapamycin was identified, a natural compound with inhibitory action on cell growth and proliferation ,3,4.PI3K-related kinase (PIKK) family. Regarding its structure, mTOR consists of two different protein complexes, mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2), that have different functionality, regulation and sensitivity to rapamycin. Both protein complexes share common components such as mTOR, mLST8  and DEPTOR (DEP domain containing mTOR interacting protein) [mTOR is an evolutionarily conserved serine-threonine kinase belonging to the protein) ,6.The specific mTORC1 proteins include Raptor (regulatory associated with mTOR)  and PRASmTORC1 was described as the direct target for rapamycin, while the subunit mTORC2 is insensitive to rapamycin acute treatment ,11, but It was described that mTORC1 and mTORC2 have distinct modes of regulation, while the main downstream activated by mTORC1 is p70-S6 kinase 1 (S6K1) and 4EBP1 ,14. mTORmTOR is considered a master regulator of homeostasis, and especially relevant is the regulation of energy balance and peripheral metabolism through its action on the CNS. Among the main general functions of the mTOR signaling pathway, the regulation of cell proliferation, metabolism and protein synthesis have been largely described ,17.It was shown that the mTOR signaling pathway has a determinant role in cell growth; specifically, mTORC1 is responsible for a balance between factors that stimulate growth and nutrient availability. Accordingly, mTORC1 is also involved in proliferation mechanisms at the cellular level, since it works as a sensor of nutrient availability in the cell, coordinating the balance between anabolic and catabolic metabolism in response to modifications of exogenous conditions ,17.In mammals, changes in energy status are highly dependent on diet, so, under feeding conditions, mTORC1 is activated to promote growth and energy storage in tissues such as the liver and muscles, while, under fasting conditions, mTORC1 is inhibited to conserve limited resources. Metabolic pathways such as glycolysis, the oxidative arm of the pentose phosphate pathway, and de novo lipid biosynthesis have been shown to be stimulated by mTORC1 activation. Moreover, mTORC1 suppresses autophagy ,17,18.Although mTORC2 signaling is less understood than mTORC1, recent studies demonstrate that mTORC2 modulates cell metabolism and regulates the organization of the actin cytoskeleton and improves cell survival due to its activation of survival kinase AKT . It has A wide spectrum of physiological functions has been described for the mTOR complex depending on the tissue in which it is expressed.The hypothalamus is the central organ integrating nutritional and hormonal signals involved in energy balance regulation . In respThe hypothalamus is constituted by a network of neurons organized in different hypothalamic nuclei. Among them, the arcuate nucleus (ARC), located next to the third ventricle, and the median eminence, have two neuronal populations with opposite effects on energy balance: the agouti-related protein (AgRP)/neuropeptideY (NPY)-producing neurons increase food intake and adiposity, while the activity of pro-opiomelanocortin (POMC)/cocaine and amphetamine-regulated transcript (CART)-producing neurons decrease food intake and adiposity. These neurons interact with other areas involved in the regulation of energy balance, such as the paraventricular nucleus (PVN), dorsomedial nucleus (DMH), ventromedial nucleus (VMH) and lateral hypothalamic area (LHA) ,24.At the central level, mTOR regulates several hypothalamic circuits involved in energy balance regulation in response to peripheral signals related to energy status. Between the main hypothalamic nuclei expressing the phosphorylated active forms of mTOR and S6K, in the arcuate nucleus, mTOR co-localizes with key neuropeptides involved in appetite regulation, such as NPY and AgRP ,26 and PmTORC1 acts as a sensor of energy status in the hypothalamus ,29,30. TNotably, nutrient-activated hypothalamic mTORC1 signaling is specific to neurons or areas. Importantly, although hypothalamic mTORC1 signaling is a critical mediator of the actions of hormones and nutrients in energy metabolism throughout the entire body, it remains to be investigated how mTORC1 signaling in different neuron populations is regulated by hormonal factors and nutrients, as it regulates distinct neuronal activity and function. Moreover, it is still unclear whether mTORC1 interacts with other energy sensors in the hypothalamus to monitor energy balance ,32.Nevertheless, it was recently proposed that hypothalamic interplay between the mTOR pathway and the 5′-adenosine monophosphate-activated protein kinase (AMPK) pathway exists to regulate energy balance. This relationship was initially proposed based on the fact that AMPK is able to regulate the activity of S6K and 4EBP1 ,34, bothOn the other hand, mTORC2 seems to be involved in the regulation of neuronal morphology and synaptic activity. However, its function in the central regulation of the energy balance is less well understood .The liver is a critical organ for systemic metabolism. In fasting state, the liver provides energy sources to peripheral tissues through ketogenesis. It was described that, in fasting states, the inhibition of mTORC1 is essential for the correct production of ketonic bodies and for maintaining glucose levels during starvation. It is also fundamental to induce the autophagy in the liver needed to provide amino acids for gluconeogenesis . RegardiHepatic mTORC2 regulates glucose and lipid metabolism by AKT signaling. Additionally, mTORC2 regulates gluconeogenesis and lipogenesis through various transcription factors, including FOXO1, FOXA2 and PPAR-γ . In addiThe main adipose tissues are white adipose tissue, which stores energy in the form of drops of triglycerides, and brown adipose tissue, which dissipates energy through decoupled breathing and heat production. mTOR has been shown to positively regulate adipogenesis and lipogenesis while inhibiting lipolysis, fatty acid oxidation and ketogenesis.The molecular mechanisms by which mTORC1 controls adipogenesis involve C/EBP-α and PPAR-γ, among other molecular targets . mTORC2 The gut–brain axis has been claimed as a key regulator of food intake and energy metabolism. New signals secreted by endocrine cells throughout the gastrointestinal tract are continuously discovered; they affect the hypothalamic centers responsible for regulating energy metabolism through its action not only on food intake but also through the modulation of different processes, such as thermogenesis and lipid metabolism, with the final effect of regulating body weight ,48. The In the hypothalamus, the mTOR pathway is proposed as an energy sensor that monitors nutrient availability and regulates energy balance and food intake . In addiAt the gastric level, the expression of the main components of the mTOR pathway is regulated by changes in nutritional status, with low levels of activation in fasting conditions returning to basal expression after refeeding . These fIt was reported that the components of the mTOR pathway are expressed in different endocrine cells, including X/A-like cells and with lower expression in G cells . SpecifiThe role of the gut–brain axis in the regulation of food intake and energy homeostasis became relevant after ghrelin isolation in 1999. Ghrelin is the only described anorexigenic peptide released from the gastrointestinal tract, regulating energy homeostasis by increasing food intake and adiposity . GhrelinThe involvement of the mTOR pathway in fuel sensing at the gastric level for the maintenance of energy homeostasis should not only be considered in relation to its effects on ghrelin regulation. Certainly, new gastrokines involved in the gut–brain axis’ regulation of body weight are continuously discovered . One of An interaction between the gastric mTOR pathway and the cannabinoid system was recently described to regulate the production of the main gastrokines involved in energy homeostasis, such as ghrelin and nesfatin-1.A few years ago, a novel mechanism of food intake regulation was described in the stomach by an interaction between the gastric cannabinoid system and ghrelin, orchestrated by the mTOR signaling pathway . The recMoreover, the effect of this gastric system on central food intake was carried out through neural control of the vagus nerve . The patHowever, the described gastric interaction between the cannabinoid system and mTOR is not only involved in ghrelin production. It was recently reported that the mTOR pathway mediates the interaction between the cannabinoid system and nesfatin-1 to modulate food intake. The inhibition of cannabinoid receptor 1 (CB1) by the peripheral injection of rimonabant decreases food intake and induces an increase in the gastric production of Nucb2/nesfatin-1, along with the activation of the mTOR pathway in the stomach. Confirming these findings, the inactivation of the intracellular pathway mTOR/S6k by chronic treatment with rapamycin blocks the stimulatory effect of rimonabant in the gastric secretion of Nucb2/nesfatin-1 .These findings altogether reveal that the intracellular mTOR pathway in the stomach mediates a gastric mechanism in which the cannabinoid system regulates the production of the anorexigenic hormone Nucb2/nesfatin-1 and the orexigenic ghrelin in an opposing manner. This works as a mechanism to balance anorectic and orexigenic signals to maintain energy homeostasis. The gastrointestinal tract and gastrokines, together with novel systems such as the endocannabinoid system and the intracellular mTOR pathway, represent promising pharmacological targets for the development of therapies against obesity.The role of gastric mTOR signaling in different physiological processes was deeply studied by using different genetic models that allow the modulation of mTOR signaling specifically in the stomach. The first of these knocked-down TSC1 in animal models, a key component of mTOR signaling in the stomach, whose inhibition induces the activation of mTOR signaling. This is an experimental model of mTOR activation specifically in the stomach, without effects on other organs in which mTOR is expressed. In addition, these mice present decreased ghrelin expression, food intake and lipid content in the liver.The described knockout model affects the global gastric cells expressing mTOR. However, the most interesting model is the one which selectively targets the mTOR pathway in gastric X/A cells, the endocrine cells that produce the main known gastrokines involved in energy homeostasis regulation, such as ghrelin and nesfatin-1. The mice model of genetic mTOR activation specifically in X/A cells presents decreased body weight and fat adipose content than its wild type without significant differences in food intake, according to unaffected expression of the main hypothalamic genes regulating appetite . The leaner phenotype of mice with activated mTOR in X/A cells is probably due to a decrease in the gastric expression and secretion of ghrelin .In the hypothalamus, the mTOR pathway is proposed as an energy sensor monitoring nutrient availability. A possible relationship between gastric X/A cells and the fibrotic process in the pancreas leading to insulin resistance has been proposed. The signals such as ghrelin and nesfatin-1 secreted from X/A cells seem to be the nexus between gastric X/A cells and pancreas function. Recent reports have described that the modulation of mTORC1 in gastric X/A cells is critical to maintain the pancreatic microenvironment. Accordingly, it was shown how the activation of the mTORC1 pathway in X/A cells induced the appearance of pancreatic fibrosis in mice, causing glucose intolerance. This effect is mediated by the decreased ghrelin production in X/A cells. In fact, pancreatic fibrosis and insulin intolerance are reversed after replacement of ghrelin by exogenous administration. In the same way, by administering rapamycin, which inhibits mTORC1, it was possible to reverse the decreased ghrelin levels and pancreatic fibrosis .−) and normal production in the pancreas and hypothalamus has no effect on body weight, food intake, plasma ghrelin levels or glucose. When this model (Ghrel−) is crossed with mice with activation of gastric mTORC1 (TSC1−/−), a new model of mice is generated that presents a decrease in the expression of plasma acyl ghrelin, gastric ghrelin and total ghrelin. In addition, a significant increase in pancreatic fibrosis was found in both thin and obese mice, but pancreatic fibrosis activation was more severe in obese mice. Mice Ghrel-TSC1−/− were found to be resistant to obesity induced by high fat intake and presented lower body weight and food intake.A mouse model with ghrelin production deficiency in X/A cells . Furthermore, these effects are independent of the affected insulin control that these mice showed .The mTOR/S6k intracellular pathway has been shown to be involved in the gastrointestinal tract in modulating the production of different signals, such as ghrelin and nesfatin-1, to regulate food intake and body weight. Furthermore, with the use of different genetic models that modulate mTOR signaling in the stomach, and specifically in gastric X/A-like cells, the relevant role of this signaling pathway in the regulation of glucose and lipid homeostasis in other tissues such as liver and adipose tissue has become evident.