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SIRT3
About: SIRT3 is a research topic. Over the lifetime, 1133 publications have been published within this topic receiving 70608 citations.
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TL;DR: It is demonstrated that SIRT1, a nicotinamide adenosine dinucleotide‐dependent histone deacetylase, regulates the transcriptional activity of NF‐κB and activity augments apoptosis in response to TNFα.
Abstract: NF‐κB is responsible for upregulating gene products that control cell survival. In this study, we demonstrate that SIRT1, a nicotinamide adenosine dinucleotide‐dependent histone deacetylase, regulates the transcriptional activity of NF‐κB. SIRT1, the mammalian ortholog of the yeast SIR2 (Silencing Information Regulator) and a member of the Sirtuin family, has been implicated in modulating transcriptional silencing and cell survival. SIRT1 physically interacts with the RelA/p65 subunit of NF‐κB and inhibits transcription by deacetylating RelA/p65 at lysine 310. Treatment of cells with resveratrol, a small‐molecule agonist of Sirtuin activity, potentiates chromatin‐associated SIRT1 protein on the cIAP‐2 promoter region, an effect that correlates with a loss of NF‐κB‐regulated gene expression and sensitization of cells to TNFα‐induced apoptosis. While SIRT1 is capable of protecting cells from p53‐induced apoptosis, our work provides evidence that SIRT1 activity augments apoptosis in response to TNFα by the ability of the deacetylase to inhibit the transactivation potential of the RelA/p65 protein.
2,437 citations
TL;DR: The role of NAD+, the unusual products of the deacetylation reaction, the Sir2 structure, and the Sir1 and Sir2 chemical inhibitors and activators that were recently identified are discussed.
Abstract: ▪ Abstract The yeast SIR protein complex has been implicated in transcription silencing and suppression of recombination. The Sir complex represses transcription at telomeres, mating-type loci, and ribosomal DNA. Unlike SIR3 and SIR4, the SIR2 gene is highly conserved in organisms ranging from archaea to humans. Interestingly, Sir2 is active as an NAD+-dependent deacetylase, which is broadly conserved from bacteria to higher eukaryotes. In this review, we discuss the role of NAD+, the unusual products of the deacetylation reaction, the Sir2 structure, and the Sir2 chemical inhibitors and activators that were recently identified. We summarize the current knowledge of the Sir2 homologs from different organisms, and finally we discuss the role of Sir2 in caloric restriction and aging.
1,521 citations
TL;DR: A human ortholog of Sir2p, sirtuin type 2 (SIRT2), is a predominantly cytoplasmic protein that colocalizes with microtubules and is established as a bona fide tubulin deacetylase.
1,434 citations
TL;DR: It is demonstrated that SIRT3 modulates mitochondrial intermediary metabolism and fatty-acid use during fasting and acetylation is identified as a novel regulatory mechanism for mitochondrial fatty- acid oxidation.
Abstract: Sirtuins are NAD(+)-dependent protein deacetylases. They mediate adaptive responses to a variety of stresses, including calorie restriction and metabolic stress. Sirtuin 3 (SIRT3) is localized in the mitochondrial matrix, where it regulates the acetylation levels of metabolic enzymes, including acetyl coenzyme A synthetase 2 (refs 1, 2). Mice lacking both Sirt3 alleles appear phenotypically normal under basal conditions, but show marked hyperacetylation of several mitochondrial proteins. Here we report that SIRT3 expression is upregulated during fasting in liver and brown adipose tissues. During fasting, livers from mice lacking SIRT3 had higher levels of fatty-acid oxidation intermediate products and triglycerides, associated with decreased levels of fatty-acid oxidation, compared to livers from wild-type mice. Mass spectrometry of mitochondrial proteins shows that long-chain acyl coenzyme A dehydrogenase (LCAD) is hyperacetylated at lysine 42 in the absence of SIRT3. LCAD is deacetylated in wild-type mice under fasted conditions and by SIRT3 in vitro and in vivo; and hyperacetylation of LCAD reduces its enzymatic activity. Mice lacking SIRT3 exhibit hallmarks of fatty-acid oxidation disorders during fasting, including reduced ATP levels and intolerance to cold exposure. These findings identify acetylation as a novel regulatory mechanism for mitochondrial fatty-acid oxidation and demonstrate that SIRT3 modulates mitochondrial intermediary metabolism and fatty-acid use during fasting.
1,339 citations
TL;DR: The notion that multiple human SIRT proteins have evolutionarily conserved and nonconserved functions at different cellular locations is supported and the lifespan of normal human cells, in contrast to that of lower eukaryotes, cannot be manipulated by increased expression of a single SIRT protein.
Abstract: Sir2 is a NAD+-dependent protein deacetylase that extends lifespan in yeast and worms. This study examines seven human proteins homologous to Sir2 (SIRT1 through SIRT7) for cellular localization, expression profiles, protein deacetylation activity, and effects on human cell lifespan. We found that: 1) three nuclear SIRT proteins (SIRT1, SIRT6, and SIRT7) show different subnuclear localizations: SIRT6 and SIRT7 are associated with heterochromatic regions and nucleoli, respectively, where yeast Sir2 functions; 2) SIRT3, SIRT4, and SIRT5 are localized in mitochondria, an organelle that links aging and energy metabolism; 3) cellular p53 is a major in vivo substrate of SIRT1 deacetylase, but not the other six SIRT proteins; 4) SIRT1, but not the other two nuclear SIRT proteins, shows an in vitro deacetylase activity on histone H4 and p53 peptides; and 5) overexpression of any one of the seven SIRT proteins does not extend cellular replicative lifespan in normal human fibroblasts or prostate epithelial cells. This study supports the notion that multiple human SIRT proteins have evolutionarily conserved and nonconserved functions at different cellular locations and reveals that the lifespan of normal human cells, in contrast to that of lower eukaryotes, cannot be manipulated by increased expression of a single SIRT protein.
1,266 citations