SIRT1 deacetylates ROR?t and enhances Th17 cell generation.
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ABSTRACT:
SUBMITTER: Lim HW
PROVIDER: S-EPMC4419343 | biostudies-literature | 2015 May
REPOSITORIES: biostudies-literature
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Project description: Not available
2014-10-22 | MSV000078902 | MassIVE
Project description:Pancreas duodenum homeobox 1 (PDX1) is essential for pancreas development and ?-cell formation; however more studies are needed to clearly illustrate the precise mechanism regarding spatiotemporal regulation of Pdx1 expression during ?-cell formation and development. Here, we demonstrate that SIRT1, FOXA2 and a number of proteins form a protein complex on the promoter of the Pdx1 gene. SIRT1 and PDX1 are expressed in the same set of cells during ?-cell differentiation and maturation. Pancreas-specific disruption of SIRT1 diminished PDX1 expression and impaired islet development. Consequently, SIRT1 mutant mice develop progressive hyperglycemia, glucose intolerance, and insulin insufficiency, which directly correlate with the extent of SIRT1 deletion. We further show that SIRT1 interacts with and deacetylates FOXA2 on the promoter of the Pdx1gene, and positively regulates its transcription. These results uncover an essential role of SIRT1 in ?-cell formation by maintaining expression of PDX1 and its downstream genes, and identify pancreas-specific SIRT1 mutant mice as a relevant model for studying insulin insufficiency.
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Project description:The RAR-related orphan receptor gamma t (RORγt) is a nuclear receptor required for generating IL-17-producing CD4(+) Th17 T cells, which are essential in host defense and may play key pathogenic roles in autoimmune diseases. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol and lipid metabolism. Here, we describe the identification of several naturally occurring oxysterols as RORγt agonists. The most potent and selective activator for RORγt is 7β, 27-dihydroxycholesterol (7β, 27-OHC). We show that these oxysterols reverse the inhibitory effect of an RORγt antagonist, ursolic acid, in RORγ- or RORγt-dependent cell-based reporter assays. These ligands bind directly to recombinant RORγ ligand binding domain (LBD), promote recruitment of a coactivator peptide, and reduce binding of a corepressor peptide to RORγ LBD. In primary cells, 7β, 27-OHC and 7α, 27-OHC enhance the differentiation of murine and human IL-17-producing Th17 cells in an RORγt-dependent manner. Importantly, we showed that Th17, but not Th1 cells, preferentially produce these two oxysterols. In vivo, administration of 7β, 27-OHC in mice enhanced IL-17 production. Mice deficient in CYP27A1, a key enzyme in generating these oxysterols, showed significant reduction of IL-17-producing cells, including CD4(+) and γδ(+) T cells, similar to the deficiency observed in RORγt knockout mice. Our results reveal a previously unknown mechanism for selected oxysterols as immune modulators and a direct role for CYP27A1 in generating these RORγt agonist ligands, which we propose as RORγt endogenous ligands, driving both innate and adaptive IL-17-dependent immune responses.
| S-EPMC4143045 | biostudies-literature
Project description:SIRT1 plays a key role in maintaining metabolic homeostasis in mammals by directly modulating the activities of various transcription factors and metabolic enzymes through lysine deacetylation. White adipose tissue plays a key role in lipid storage and metabolism. To identify novel molecular targets of SIRT1 in fat cells, we used a non-biased proteomic approach. We identified a number of proteins whose acetylation status was significantly affected by SIRT1 modulator treatment in 3T3-L1 adipocytes. Among them, ATP6V1B2, a subunit of the vacuolar (H+)-ATPase, was further shown to be associated with SIRT1 by co-immunoprecipitation assay. Moreover, SIRT1 deacetylates ATP6V1B2 in vitro and in vivo. Taken together, our study demonstrates that ATP6V1B2 is a molecular target of SIRT1 in fat cells and the role of SIRT1 and ATP6V1B2 acetylation in the vacuolar (H+)-ATPase function warrants further investigation.
| S-EPMC4503461 | biostudies-literature
Project description:p62/SQSTM1 is frequently up-regulated in many cancers including hepatocellular carcinoma. Highly expressed p62 promotes hepato-carcinogenesis by activating many signaling pathways including Nrf2, mTORC1, and NFκB signaling. However, the underlying mechanism for p62 up-regulation in hepatocellular carcinoma remains largely unclear. Herein, we confirmed that p62 was up-regulated in hepatocellular carcinoma and its higher expression was associated with shorter overall survival in patients. The knockdown of p62 in hepatocellular carcinoma cells decreased cell growth in vitro and in vivo. Intriguingly, p62 protein stability could be reduced by its acetylation at lysine 295, which was regulated by deacetylase Sirt1 and acetyltransferase GCN5. Acetylated p62 increased its association with the E3 ligase Keap1, which facilitated its poly-ubiquitination-dependent proteasomal degradation. Moreover, Sirt1 was up-regulated to deacetylate and stabilize p62 in hepatocellular carcinoma. Additionally, Hepatocyte Sirt1 conditional knockout mice developed much fewer liver tumors after Diethynitrosamine treatment, which could be reversed by the re-introduction of exogenous p62. Taken together, Sirt1 deacetylates p62 at lysine 295 to disturb Keap1-mediated p62 poly-ubiquitination, thus up-regulating p62 expression to promote hepato-carcinogenesis. Therefore, targeting Sirt1 or p62 is a reasonable strategy for the treatment of hepatocellular carcinoma.
| S-EPMC8046979 | biostudies-literature
Project description:Th17 cells, a lymphocyte subpopulation that is characterized by the expression of the transcription factor "retinoic acid receptor-related orphan receptor gamma-t" (RORγt), plays an important role in the pathogenesis of autoimmune disease. The current study was set up to discover novel and non-steroidal small-molecule inverse agonists of RORγt and to determine their effects on autoimmune disease. Structure-based virtual screening (SBVS) was used to find compounds targeting RORγt. Flow cytometry was used to detect the Th17 cell differentiation. Inverse agonists were intraperitoneally administered to mice undergoing experimental autoimmune uveitis (EAU), experimental autoimmune encephalomyelitis (EAE) or type 1 diabetes. The effects of the inverse agonists were evaluated by clinical or histopathological scoring. Among 1.3 million compounds screened, CQMU151 and CQMU152 were found to inhibit Th17 cell differentiation without affecting the differentiation of Th1 and Treg lineages (both P = 0.001). These compounds also reduced the severity of EAU (P = 0.01 and 0.013) and functional studies showed that they reduced the number of Th17 cell and the expression of IL-17(Th17), but not IFN-γ(Th1) and TGF-β(Treg) in mouse retinas. Further studies showed that these compounds may reduce the expression of p-STAT3 by reducing the positive feedback loop of IL-17/IL-6/STAT3. These compounds also reduced the impaired blood-retinal barrier function by upregulating the expression of tight junction proteins. These compounds were also found to reduce the severity of EAE and type 1 diabetes. Our results showed that RORγt inverse agonists may inhibit the development of autoimmune diseases and may provide new clues for the treatment of Th17-mediated immune diseases.
| S-EPMC7443190 | biostudies-literature
Project description:Although Th17 responses may contribute to the pathogenesis of glomerulonephritis, whether the key transcription factor in Th17 cell development, RORγt, also promotes glomerulonephritis is unknown. Here, we induced crescentic glomerulonephritis in wild-type and RORγt-deficient (RORγt(-/-)) mice. RORγt(-/-) mice were protected from disease, with reduced histologic and functional injury and decreased leukocyte infiltration. Because RORγt(-/-) mice lack lymph nodes, which may influence the development of nephritis, we performed cell-transfer studies. We reconstituted Rag1(-/-) mice, which lack adaptive immunity but otherwise have normal architecture of the lymphatic system, with splenocytes from naïve wild-type or RORγt(-/-) mice. Mice receiving wild-type splenocytes exhibited high mortality from renal failure after induction of nephritis whereas mice receiving RORγt(-/-) cells were protected. To determine the effect of RORγt deficiency specifically in T helper cells, we isolated naïve CD4(+) T cells from wild-type and RORγt(-/-) mice and transferred them into Rag1(-/-) animals. Recipients of wild-type CD4(+) T cells developed severe glomerulonephritis whereas recipients of RORγt(-/-) cells developed less severe disease. To exclude effects of altered regulatory T cell (Treg) development caused by RORγt deficiency, we transferred naïve CD4(+) T cells depleted of Tregs into Rag1(-/-) mice. Recipients of wild-type, Treg-depleted, CD4(+) T cells developed severe glomerulonephritis whereas recipients of RORγt(-/-), Treg-depleted CD4(+) T cells did not. Taken together, this study demonstrates that RORγt promotes the development of crescentic glomerulonephritis by directing nephritogenic Th17 responses.
| S-EPMC3060441 | biostudies-literature
Project description:Th17 cells represent important immune cells. Ursolic acid (UA) can regulate immune cell activities. This study was aimed to explore the effects of UA on Th17 cell differentiation and Schwann cell(SCs)-mediated migration and the potential mechanism. Naïve CD4+ T cells were isolated from rat peripheral blood, induced for Th17 cell differentiation, and treated with UA. The proportion of Th17 cells was detected by flow cytometry assay. SCs were co-cultured with Th17 cells. Th17 cell migration was detected by Transwell assay. The molecule expression was determined by Western blot and qRT-PCR. UA inhibited the Th17 cell differentiation and suppressed the STAT3/RORγt pathway. STAT3 overexpression up-regulated p-STAT3 and RORγt expression and promoted Th17 cell differentiation under the UA treatment. In LPS- and IFN-γ-stimulated-SCs, UA suppressed the expression of chemokines CXCL9/10, but had no significant effect of CCL20 expression. The expression CXCL9/10 receptor CXCR3 was higher in Th17 cells than that in Treg cells, while the expression CCL20 receptor CCR6 was lower in Th17 cells than that in Treg cells. UA, anti-CXCR3, and anti-CCR6 treatment inhibited SCs-mediated Th17 cell migration, and anti-CXCR3 exerted stronger inhibitory effect than Anti-CCR6. UA inhibited Th17 cell differentiation through STAT3/RORγt pathway and suppressed Th17 cell migration through down-regulating CXCL9/10 expression in SCs.
| S-EPMC9189552 | biostudies-literature
Project description:RORγt and RORα are transcription factors of the RAR-related orphan nuclear receptor (ROR) family. They are expressed in Th17 cells and have been suggested to play a role in Th17 differentiation. Although RORγt signature genes have been characterized in mouse Th17 cells, detailed information on its transcriptional control in human Th17 cells is limited and even less is known about RORα signature genes which have not been reported in either human or mouse T cells. In this study, global gene expression of human CD4 T cells activated under Th17 skewing conditions was profiled by RNA sequencing. RORγt and RORα signature genes were identified in these Th17 cells treated with specific siRNAs to knock down RORγt or RORα expression. We have generated selective small molecule RORγt modulators and they were also utilized as pharmacological tools in RORγt signature gene identification. Our results showed that RORγt controlled the expression of a very selective number of genes in Th17 cells and most of them were regulated by RORα as well albeit a weaker influence. Key Th17 genes including IL-17A, IL-17F, IL-23R, CCL20 and CCR6 were shown to be regulated by both RORγt and RORα. Our results demonstrated an overlapping role of RORγt and RORα in human Th17 cell differentiation through regulation of a defined common set of Th17 genes. RORγt as a drug target for treatment of Th17 mediated autoimmune diseases such as psoriasis has been demonstrated recently in clinical trials. Our results suggest that RORα could be involved in same disease mechanisms and gene signatures identified in this report could be valuable biomarkers for tracking the pharmacodynamic effects of compounds that modulate RORγt or RORα activities in patients.
| S-EPMC5538713 | biostudies-literature
Project description:Mesenchymal stem cell (MSC)-derived small extracellular vesicles (MSC-sEVs) are known to exert immunosuppressive functions. This study showed that MSC-sEVs specifically convert T helper 17 (Th17) cells into IL-17 low-producer (ex-Th17) cells by degrading RAR-related orphan receptor γt (RORγt) at the protein level. In experimental autoimmune encephalomyelitis (EAE)-induced mice, treatment with MSC-sEVs was found to not only ameliorate clinical symptoms but also to reduce the number of Th17 cells in draining lymph nodes and the central nervous system. MSC-sEVs were found to destabilize RORγt by K63 deubiquitination and deacetylation, which was attributed to the EP300-interacting inhibitor of differentiation 3 (Eid3) contained in the MSC-sEVs. Small extracellular vesicles isolated from the Eid3 knockdown MSCs by Eid3-shRNA failed to downregulate RORγt. Moreover, forced expression of Eid3 by gene transfection was found to significantly decrease the protein level of RORγt in Th17 cells. Altogether, this study reveals the novel immunosuppressive mechanisms of MSC-sEVs, which suggests the feasibility of MSC-sEVs as an attractive therapeutic tool for curing Th17-mediated inflammatory diseases.
| S-EPMC10073130 | biostudies-literature