The SIRT3-DsbA-L-TFAM Axis Suppresses Liver cGAS Signaling and MASH Progression in Male Mice
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PROVIDER: PRJNA1185201 | ENA |
REPOSITORIES: ENA
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Project description:While mitochondrial dysfunction is implicated in metabolic dysfunction associated steatohepatitis (MASH), the precise underlying mechanisms remain obscure. Here, we identify the SIRT3-DsbA-L-TFAM axis as a crucial suppressor for mitochondrial stress-induced cGAS activation in the hepatocytes, thereby alleviating MASH in mice. SIRT3 facilitates the deacetylation of Disulfide-bond-A oxidoreductase-like protein (DsbA-L) at lysine residues (Lys165, Lys167, and Lys177), which promotes the interaction between DsbA-L and mitochondrial transcription factor A (TFAM), essential for the preservation of mitochondrial integrity and function. Hepatocyte-specific knockout of SIRT3 or DsbA-L in male mice promoted mitochondrial DNA release into the cytosol, resulting in activation of the cGAS-STING pathway and exacerbation of MASH characteristics. Conversely, hepatocyte-specific knockout of cGAS or overexpression of DsbA-L mitigated diet- and SIRT3 deficiency-induced MASH progression. Our study underscores the clinical significance of targeting SIRT3 and cGAS as pivotal therapeutic avenues to inhibit the progression of MASH.
2024-11-30 | GSE281667 | GEO
Project description:SIRT3 is a NAD+-dependent mitochondrial protein deacetylase participating in the regulation of central metabolism and mitochondrial proteostasis. SIRT3 is downregulated in clear cell renal cell carcinoma (ccRCC), a main type of renal cancers, but the function of SIRT3 in tumorigenesis and development of ccRCC remains unknown. In this study, we established a SIRT3 overexpressed cell line to explore the changes of proteomics and metabolomics regulated by SIRT3 expression. Both the results of quantitative proteomics, metabolomics and acetylome showed overexpression of SIRT3 increased mitochondrial biogenesis and reversed the mitochondrial dysfunctions in ccRCC. We found SIRT3 could increase the activity of TFAM through modulation of TFAM transcription, degradation and acetylation level. The acetylation of TFAM K154 decreased while TFAM protein expression increased after SIRT3 overexpression. Further study revealed that SIRT3 could bind with TFAM, and decrease the acetylation of TFAM, promoting TFAM activity in mitochondrial biogenesis. Overall, our results present a new mechanism of SIRT3 in regulating mitochondrial functions, and the downregulation of SIRT3 in ccRCC lowers the activity of TFAM, subsequently inhibits the transcription of mitochondrial genes and mitochondrial biogenesis.
2018-08-14 | PXD009110 | Pride
Project description:The goal of this analysis was to utilize microarray profiling to identify basal alterations in gene expression in response to TFAM depletion and mtDNA stress. Mitochondrial DNA (mtDNA) is normally present at thousands of copies per cell and is packaged into several hundred higher-order structures termed nucleoids. The abundant mtDNA-binding protein, TFAM (transcription factor A,mitochondrial), regulates nucleoid architecture, abundance and segregation. Complete mtDNA depletion profoundly impairs oxidative phosphorylation, triggering calcium-dependent stress signalling and adaptive metabolic responses. However, the cellular responses to mtDNA instability, a physiologically relevant stress observed in many human diseases and ageing, remain poorly defined. Here we show that moderate mtDNA stress elicited by TFAM deficiency engages cytosolic antiviral signalling to enhance the expression of a subset of interferon-stimulated genes. Mechanistically, we find that aberrant mtDNA packaging promotes escape of mtDNA into the cytosol, where it engages the DNA sensor cGAS (also known as MB21D1) and promotes STING (also known as TMEM173)–IRF3-dependent signalling to elevate interferon-stimulated gene expression, potentiate type I interferon responses and confer broad viral resistance. Furthermore, we demonstrate that herpesviruses induce mtDNA stress, which enhances antiviral signalling and type I interferon responses during infection. Our results further demonstrate that mitochondria are central participants in innate immunity, identify mtDNA stress as a cell-intrinsic trigger of antiviral signaling and suggest that cellular monitoring of mtDNA homeostasis cooperates with canonical virus sensing mechanisms to fully engage antiviral innate immunity. Murine embryonic fibroblasts were isolated from wild-type or Tfam+/- E13.5 littermate embryos. RNA from passage-matched wild-type and Tfam+/- MEF lines was extracted in duplicate and hybridized onto Affymetrix microarrays. Four arrays were performed in total with two technical replicates per genotype.
2015-01-26 | E-GEOD-63767 | biostudies-arrayexpress
Project description:Tumor cells exhibit aberrant metabolism characterized by high glycolysis even in the presence of oxygen. This metabolic reprogramming, known as the Warburg effect, provides tumor cells with the substrates and redox potential required for the generation of biomass. Here, we show that the mitochondrial NAD-dependent deacetylase SIRT3 is a crucial regulator of the Warburg effect. SIRT3 loss promotes a metabolic profile consistent with high glycolysis required for anabolic processes in vivo and in vitro. Mechanistically, SIRT3 mediates metabolic reprogramming independently of mitochondrial oxidative metabolism and through HIF1a, a transcription factor that controls expression of key glycolytic enzymes. SIRT3 loss increases reactive oxygen species production, resulting in enhanced HIF1a stabilization. Strikingly, SIRT3 is deleted in 40% of human breast cancers, and its loss correlates with the upregulation of HIF1a target genes. Finally, we find that SIRT3 overexpression directly represses the Warburg effect in breast cancer cells. In sum, we identify SIRT3 as a regulator of HIF1a and a suppressor of the Warburg effect. RNA isolated from brown adipose tissue of SIRT3 WT and KO mice. 5 wild-type samples and 5 SIRT3 KO samples
2011-03-15 | E-GEOD-27309 | biostudies-arrayexpress
Project description:CK1α suppresses autoimmunity by restraining the cGAS-STING signaling
| PRJNA940749 | ENA
Project description:ChIP-seq data characterizing the occupancy of TFAM over the mitochondrial and nuclear genomes in HeLa cells. Characterization of mitochondrial and nuclear genome-wide TFAM binding in HeLa cells
2013-09-21 | E-GEOD-48176 | biostudies-arrayexpress
Project description:SIRT3 is a member of the Sir2 family of NAD+-dependent protein deacetylases that promotes longevity in many organisms. The processed, short form of SIRT3 is a well-established mitochondrial protein whose deacetylase activity regulates various metabolic processes. However, the presence of full-length (FL) SIRT3 in the nucleus and its functional importance remains controversial. Our previous studies demonstrated that nuclear FL-SIRT3 functions as a histone deacetylase and is transcriptionally repressive when artificially recruited to a reporter gene. Here, we report that nuclear FL-SIRT3 is subjected to rapid degradation upon cellular stress, including oxidative stress and UV-irradiation, whereas the mitochondrial, processed form is unaffected. FL-SIRT3 degradation is mediated by the ubiquitin-proteasome pathway, at least partially through the E3 activity of SKP2. Finally, we show by chromatin immunoprecipitation that some target genes of nuclear SIRT3 are derepressed upon the degradation of SIRT3 caused by stress stimuli. Thus, SIRT3 exhibits a previously unappreciated role in the nucleus modulating the expression of some stress-related and nuclear-encoded mitochondrial genes. ChIP-seq with a SIRT3 antibody in untreated, UV-irradiated, and stable SIRT3 knockdown (KD) U2OS cells
2012-10-16 | E-GEOD-41000 | biostudies-arrayexpress
Project description:Acetylation is frequently detected on mitochondrial enzymes and the sirtuin deacetylase SIRT3 is thought to regulate metabolism by deacetylating mitochondrial proteins. However, the stoichiometry of acetylation has not been studied and is important for understanding whether SIRT3 regulates or suppresses acetylation. Using quantitative mass spectrometry we measured acetylation stoichiometry in mouse liver tissue and found that SIRT3 suppressed acetylation to a very low stoichiometry at its target sites. By examining acetylation changes in the liver, heart, brain, and brown adipose tissue of fasted mice, we found that SIRT3-targeted sites were mostly unaffected by fasting, a dietary manipulation that is thought to regulate metabolism through SIRT3-dependent deacetylation. Globally increased mitochondrial acetylation in fasted liver tissue, higher stoichiometry at mitochondrial acetylation sites, and greater sensitivity of SIRT3-targeted sites to chemical acetylation in vitro and fasting in vivo, suggests a nonenzymatic mechanism of acetylation. Our data indicate that most mitochondrial acetylation occurs as a low-level nonenzymatic protein lesion and that SIRT3 functions as a protein repair factor that removes acetylation lesions from lysine residues.
2015-09-15 | PXD000885 | Pride
Project description:Gene expression analysis of 2-month-old Ctrl and Tfam-SCKO mice. At this age mitochondrial function is disrupted in the Schwann cells of Tfam-SCKO mice ,but their nerves display only very limited pathology. Mitochondrial dysfunction is a common cause of peripheral neuropathy. Much effort has been devoted to examining the role played by neuronal/axonal mitochondria, but how mitochondrial deficits in peripheral nerve glia (Schwann cells, SCs) contribute to peripheral nerve diseases remains unclear. Here, we investigate a mouse model of peripheral neuropathy secondary to SC mitochondrial dysfunction (Tfam-SCKOs). We show that disruption of SC mitochondria activates a maladaptive integrated stress response through actions of heme-regulated inhibitor kinase (HRI), and causes a shift in lipid metabolism away from fatty acid synthesis toward oxidation. These alterations in SC lipid metabolism result in depletion of important myelin lipid components as well as in accumulation of acylcarnitines, an intermediate of fatty acid b-oxidation. Importantly, we show that acylcarnitines are released from SCs and induce axonal degeneration. A maladaptive integrated stress response as well as altered SC lipid metabolism are thus underlying pathological mechanisms in mitochondria-related peripheral neuropathies. Total RNA samples were prepared by isolating and pooling RNA from three different 2-month-old MPZ-Tfam KO and Ctrl mice. 2 replicates per genotype were used in this experiment and they were prepared entirely independently.
2013-03-13 | E-GEOD-44605 | biostudies-arrayexpress
Project description:SIRT3 is a mitochondrial NAD(+)-dependent protein deacetylase, which regulates the enzymatic activity of several mitochondrial proteins. We used microarrays to identify the differences in gene expression as a result of loss of SIRT3, under standard and high-fat diet conditions Wild-type and SIRT3KO mice were sacrificed at 12weeks of age and RNA was extracted from liver tissue, and hybridized on Affymetrix microarrays, to determine differences in gene expression as a result of diet
2011-07-11 | E-GEOD-30552 | biostudies-arrayexpress