PAHSAs reduce cellular senescence and protect pancreatic beta cells from metabolic stress through regulation of Mdm2/p53
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ABSTRACT:
PROVIDER: PRJNA891772 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR21966135.fastq.gz | Fastqsanger.gz | |||
| SRR21966136.fastq.gz | Fastqsanger.gz | |||
| SRR21966137.fastq.gz | Fastqsanger.gz | |||
| SRR21966138.fastq.gz | Fastqsanger.gz | |||
| SRR21966139.fastq.gz | Fastqsanger.gz |
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Project description:Senescence in pancreatic beta cells plays a major role in beta cell dysfunction which leads to impaired glucose homeostasis and diabetes. Therefore, prevention of beta cell senescence could reduce the risk of diabetes. Treatment of NOD mice, a model of Type 1 autoimmune diabetes (T1D), with Palmitic acid hydroxy stearic acids (PAHSAs), a novel class of endogenous lipids with antidiabetic and anti-inflammatory effects, delays the onset and reduces the incidence of T1D from 82% with vehicle treatment to 35% with PAHSAs. Here we show that a major mechanism by which PAHSAs protect islets of the NOD mice is by directly preventing and reversing the initial steps of metabolic stress-induced senescence. In vitro PAHSAs increased Mdm2 expression, which decreases the stability of p53, a key inducer of senescence-related genes. In addition, PAHSAs enhanced expression of protective genes, such as those regulating DNA repair and glutathione metabolism, and promoting autophagy. We demonstrate the translational relevance by showing that PAHSAs prevent and reverse early stages of senescence in metabolically-stressed human islets by the same Mdm2 mechanism. Thus, a major mechanism for the dramatic effect of PAHSAs to reduce the incidence of Type 1 diabetes in NOD mice is by decreasing cellular senescence; PAHSAs may have a similar benefit in humans.
2022-11-03 | GSE216051 | GEO
Project description:Heat shock transcription factor 1 (HSF1) regulates the expression of a wide array of genes, controlling expression of heat shock proteins (HSPs) and cell growth. Although acute depletion of HSF1 induces cellular senescence, the underlying mechanisms are poorly understood. Here, we report that HSF1 depletion-induced senescence (HDIS) of human diploid fibroblasts (HDFs) was independent of HSP-mediated proteostasis, but dependent on activation of the p53-p21 pathway, partly because of increased expression of dehydrogenase/reductase 2 (DHRS2), a putative MDM2 inhibitor. We observed that HDIS occurred without decreased levels of major HSPs or increased proteotoxic stress in HDFs. Additionally, an inhibitor of HSP70 family proteins increased proteotoxicity and suppressed cell growth, but failed to induce senescence. Importantly, we found that activation of the p53-p21 pathway due to reduced MDM2-dependent p53 degradation was required for HDIS. Furthermore, we provide evidence that increased DHRS2 expression contribute to p53 stabilization and HDIS. Collectively, our observations uncovered a molecular pathway in which HSF1 depletion-induced DHRS2 expression leads to activation of the MDM2-p53-p21 pathway required for HDIS.
2018-05-01 | GSE111355 | GEO
Project description:CDK4 inhibitors have reached clinical approval for cancer therapy. In parallel, the p53 antagonist Mdm2 remains an attractive target for anti-cancer therapy, including numerous clinical studies. The genes encoding Mdm2 and CDK4 are frequently co-amplified in human malignancies, most notably in liposarcomas, suggesting their combined targeting for therapy. Here we show, however, that small compounds that inhibit Mdm2 and CDK4 antagonize each other rather than synergize in their cytotoxicity towards sarcoma cells. CDK4 inhibition attenuates the induction of p53-responsive genes upon Mdm2 inhibition, and similar results were obtained when depleting Mdm2 and/or CDK4 with siRNA. CDK4 inhibitors also interfered with p53 activity in response to DNA damage. CDK4 inhibition did not reduce p53 binding or histone acetylation to promoters, but rather attenuated the subsequent recruitment of RNA polymerase II. The complexes of p53 and Mdm2, as well as CDK4 and Cyclin D1, physically associated with each other. Upon combined inhibition of Mdm2 and CDK4/6, the interaction of this complex was impaired. Thus, the CDK4-Cyclin D1 complex plays a key role in enabling the transcription of p53 target genes. Taken together, our results raise caution regarding the combination of CDK4 inhibitors with Mdm2 antagonists or conventional DNA-damaging chemotherapeutics in the clinics. Moreover, they suggest a hitherto unknown role for CDK4-cyclin D1 complex in sustaining p53 activity, possibly focusing p53-mediated transcription on actively proliferating cells.
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Project description:KT-253 is a potent and selective heterobifunctional MDM2 degrader with superior activity to MDM2/p53 small molecule inhibitors. RS4;11 cells treated with KT-253 indicated no off-target protein degradation. All significantly upregulated proteins are p53 and its target genes. KT-253 overcomes p53/MDM2 feedback loop. Targeted proteomics analysis of MDM2 levels in RS4;11 cells shows that KT-253 (150 nM KT-253 for 15 minutes) can achieve greater than 90% degradation of MDM2 within 1 hour posttreatment, whereas MDM2 levels continued to increase 1 hour after treatment with DS-3032 A single dose of KT-253 drives sustained tumor regression in ALL xenografts. Targeted proteomic analysis of tumors demonstrates robust degradation of MDM2 1-hour post dosing with KT-253. This is associated with activation of the p53 pathway as evidenced by a corresponding upregulation of proteomics biomarkers p53, p21, and PHLDA3.
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Project description:Mice on two different ketogenic diets induce p53 and cellular senescence in multiple organs, including heart and kidney. This is mediated through inactivation of MDM2 by caspase-2 cleavage, leading to p53 accumulation and induction of p21. Ketogenic diet also induced pAMPK, suggesting that persistent activation leads to p53-dependent senescence.
2024-04-12 | GSE233831 | GEO
Project description:Defective glucose-stimulated insulin secretion (GSIS) and β-cell senescence are hallmarks in diabetes. The mitochondrial enzyme pyruvate carboxylase (PC) has been shown to promote GSIS and β-cell proliferation in the clonal β-cell lines, yet its physiological relevance remains unknown. Here, we provide animal and human data showing a role of PC in protecting β-cells against senescence and maintaining GSIS under different physiological and pathological conditions. β-cell-specific deletion of PC impaired GSIS and induced β-cell senescence in the mouse models under either a standard chow diet or prolonged high-fat diet feeding. Transcriptomic analysis indicated that p53-related senescence and cell cycle arrest are activated in PC-deficient islets. Overexpression of PC inhibited hyperglycemia- and aging-induced p53-related senescence in human and mouse islets as well as INS-1E β-cells, whereas knockdown of PC provoked senescence. Mechanistically, PC interacted with MDM2 to prevent its degradation via the MDM2 binding motif, which in turn restricts the p53-dependent senescent program in β-cells. On the contrary, the regulatory effects of PC on GSIS and the tricarboxylic acid (TCA) anaplerotic flux are p53-independent. We illuminate a function of PC in controlling β-cell senescence through the MDM2–p53 axis.
2024-10-10 | GSE278865 | GEO
Project description:Circular RNAs (circRNAs) are a class of noncoding RNAs produced by a non-canonical form of alternative splicing called back-splicing. To investigate a potential role of circRNAs in the p53 pathway, we analyzed RNA-seq data from colorectal cancer cell lines (HCT116, RKO and SW48) in the presence or absence of DNA damage. Surprisingly, unlike the strong p53-dependent induction of hundreds of p53-induced mRNAs, only a few circRNAs were induced from the p53-induced genes. Circ-MDM2, an annotated circRNA from the MDM2 locus, was one of the handful of circRNAs that originated from a p53-induced gene. Given the central role of MDM2 in suppressing p53 protein levels and p53 activity, we investigated the function of circ-MDM2. Knocking down circ-MDM2 with siRNAs that targeted the circ-MDM2 junction and had no effect on linear MDM2 mRNA, resulted in increased basal p53 levels and growth defects in vitro and in vivo. Consistent with these results, transcriptome profiling showed increased expression of several direct p53 targets, reduced Rb phosphorylation and defects in G1-S progression upon silencing circ-MDM2. Our results reveal the role of a novel circRNA by which the MDM2 locus suppresses p53 levels and cell cycle progression.
2020-03-04 | GSE138016 | GEO
Project description:The Mdm2 oncoprotein ubiquitinates and antagonizes p53 but may also carry out p53-independent functions. Here we report that Mdm2 is required for the efficient generation of induced pluripotent stem cells (iPSCs) from murine embryonic fibroblasts, in the absence of p53. Similarly, Mdm2 depletion in the context of p53 deficiency also promoted the differentiation of human mesenchymal stem cells and diminished clonogenic survival of cancer cells. Most of the Mdm2-controlled genes also responded to the inactivation of the Polycomb Repressor Complex 2 (PRC2) and its catalytic component EZH2. Mdm2 physically associated with EZH2 on chromatin, enhancing the trimethylation of Histone 3 at lysine 27 and the ubiquitination of Histone 2A at lysine 119 (H2AK119) at its target genes. Removing Mdm2 simultaneously with the H2AK119 E3 ligase Ring1B/RNF2 further induced these genes and synthetically arrested cell proliferation. In conclusion, Mdm2 supports the Polycomb-mediated repression of lineage specific genes independent of p53. Expression profiling by high throughput sequencing of p53 ko MEFs, p53Mdm2 ko MEFs, p53ko Mdm2 C462A ki MEFs.
2015-12-31 | E-GEOD-73176 | biostudies-arrayexpress
Project description:The Mdm2 oncoprotein ubiquitinates and antagonizes p53 but may also carry out p53-independent functions. Here we report that Mdm2 is required for the efficient generation of induced pluripotent stem cells (iPSCs) from murine embryonic fibroblasts, in the absence of p53. Similarly, Mdm2 depletion in the context of p53 deficiency also promoted the differentiation of human mesenchymal stem cells and diminished clonogenic survival of cancer cells. Most of the Mdm2-controlled genes also responded to the inactivation of the Polycomb Repressor Complex 2 (PRC2) and its catalytic component EZH2. Mdm2 physically associated with EZH2 on chromatin, enhancing the trimethylation of Histone 3 at lysine 27 and the ubiquitination of Histone 2A at lysine 119 (H2AK119) at its target genes. Removing Mdm2 simultaneously with the H2AK119 E3 ligase Ring1B/RNF2 further induced these genes and synthetically arrested cell proliferation. In conclusion, Mdm2 supports the Polycomb-mediated repression of lineage specific genes independent of p53. microarray analysis in HCT116 p53-/-cells
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Project description:RNA-sequencing was performed to gain insight into the mechanism responsible for the apoptosis and cell cycle arrest induced by loss of Mdm2 in p53-null cells. Following CreERT2-mediated deletion of Mdm2 in three p53-null cell types (T cell lymphoma, sarcoma, and fibroblasts), RNA-sequencing was performed. This high-throughput data revealed Mdm2 deletion in p53-null cells upregulated p53/p73 transcriptional target genes known to induce apoptosis and cell cycle arrest.
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