Project description:We found that lipid-derived acetyl-CoA is a major source of carbon for histone acetylation. Gene expression profiling of octanoate-treated hepatocytes identified a pattern of upregulated lipid metabolic genes, demonstrating a specific transcriptional response to lipid. These studies expand the landscape of nutrient sensing and uncover how lipids and metabolism are integrated by epigenetic events that control gene expression.
Project description:From McDonnell et. al. Cell Reports 2016: Cells integrate nutrient sensing and metabolism to coordinate proper cellular responses to a particular nutrient source. For example, glucose drives a gene expression program characterized by activating genes involved in its metabolism, in part, by increasing glucose-derived histone acetylation. Here, we find that lipid-derived acetyl-CoA is a major source of carbon for histone acetylation. Using 13C-carbon tracing combined with acetyl-proteomics, we show that up to 90% of acetylation on certain histone lysines can be derived from fatty acid carbon, even in the presence of excess glucose. By repressing both glucose and glutamine metabolism, fatty acid oxidation reprograms cellular metabolism leading to increased lipid-derived acetyl-CoA. Gene expression profiling of octanoate-treated hepatocytes shows a pattern of upregulated lipid metabolic genes, demonstrating a specific transcriptional response to lipid. These studies expand the landscape of nutrient sensing and uncover how lipids and metabolism are integrated by epigenetic events that control gene expression.
Project description:Histone acetylation involves the transfer of a two-carbon unit to nucleus as embedded in low-concentration metabolites. We find that lactate, a high-concentration metabolic by-product, can be a major carbon source for histone acetylation, through oxidation-dependent metabolism. Both in cells and in purified nucleus, 13C3-lactate carbons are incorporated into histone H4 (maximum incorporation: ~60%). In purified nucleus, this process depends on nucleus-localized lactate dehydrogenase (LDHA), the knockout of which abrogates the incorporation. Heterologous expression of nucleus-localized LDHA rescues the KO effect. Lactate itself increases histone acetylation, whereas inhibition of LDHA reduces the acetylation. In vitro and in vivo settings exhibit different lactate incorporation patterns, suggesting an influence of the microenvironment. Higher nuclear LDHA localization is observed in pancreatic cancer than in normal tissues, showing the disease relevance. Overall, lactate and nuclear LDHA can be major structural and regulatory players in the metabolism-epigenetics axis controlled by cell’s own or environmental status.
Project description:Histone modifications commonly integrate environmental stimuli to cellular metabolic outputs by affecting gene expression. Many modifications, including some histone acetylation marks, do not always correlate to transcription, thus pointing towards an alternative role of histone modifications as potential metabolic reservoirs. Using an approach that integrates mass spectrometry- based epi-proteomics and metabolomics with stable isotope tracer studies, we demonstrate that elevated lipids in histone acetyltransferase (HAT)-depleted hepatocytes result from carbon atoms flowing from the deacetylation of multi-acetylated histone H4 to fatty acids. Consistent with this, the enhanced lipid synthesis in HAT-depleted hepatocytes is dependent on the activity of histone deacetylases (HDACs) and acetyl-CoA synthetase ACSS2. Furthermore, we show that during diet-induced lipid synthesis there is a reduction of multi-acetylated histone H4 in hepatocytes and in mouse liver. In addition, overexpression of histone acetyltransferases can reverse diet-induced lipogenesis by blocking lipid droplet accumulation and maintaining the levels of multi-acetylated histone H4. This study unveils an additional link between epigenetics and metabolism whereby histone acetylation reservoirs may serve as a carbon source for lipid synthesis.
Project description:Although lipid-derived acetyl-CoA is a major carbon source for histone acetylation, the contribution of fatty acid -oxidation (FAO) to this process remains poorly characterized. To investigate this, we generated mitochondrial acetyl-CoA acetyltransferase 1 (ACAT1, distal FAO enzyme) knockout macrophages. 13C-carbon tracing confirmed reduced FA-derived carbon incorporation into histone H3 and RNA-seq identified diminished interferon stimulated gene expression in the absence of ACAT1. Chromatin accessibility at Stat1 locus was diminished in ACAT1-/- cells. CHIP analysis demonstrated reduced acetyl-H3 binding to Stat1 promoter/enhancer regions and increasing histone acetylation rescued Stat1 expression. IFNβ release was blunted in ACAT1-/- and recovered by ACAT1 reconstitution. Furthermore, ACAT1-dependent histone acetylation required an intact acetylcarnitine shuttle. Finally, obese subjects’ monocytes exhibited increased ACAT1 and histone acetylation levels. Thus, our study identifies a novel link between FAO-mediated epigenetic control of type 1 interferon signaling and uncovers a potential mechanistic link between obesity and type I inferon signaling.
Project description:Acetyl-CoA is a key intermediate in metabolism situated at the intersection of many metabolic pathways. The reliance of histone acetylation on acetyl-CoA enables gene expression to be coordinated with metabolic state. Previous studies have linked abundant histone acetylation to activation of genes involved in cell growth or tumorigenesis. However, under glucose starvation, the extent to which histone acetylation is important for gene expression remains poorly understood. Here, we use a yeast starvation model to unravel a dramatic alteration in global occupancy of histone acetylation following carbon starvation. We observe a shift in the location of histone acetylation marks from growth-promoting genes to genes required for gluconeogenesis and fat metabolism. This switch is mediated by both the histone deacetylase Rpd3 and the Gcn5p/SAGA acetyltransferase. Our findings reveal a striking specificity for histone acetylation in promoting pathways that generate acetyl-CoA for oxidation when intracellular acetyl-CoA is limiting .
Project description:Acetyl-CoA is a key intermediate in metabolism situated at the intersection of many metabolic pathways. The reliance of histone acetylation on acetyl-CoA enables gene expression to be coordinated with metabolic state. Previous studies have linked abundant histone acetylation to activation of genes involved in cell growth or tumorigenesis. However, under glucose starvation, the extent to which histone acetylation is important for gene expression remains poorly understood. Here, we use a yeast starvation model to unravel a dramatic alteration in global occupancy of histone acetylation following carbon starvation. We observe a shift in the location of histone acetylation marks from growth-promoting genes to genes required for gluconeogenesis and fat metabolism. This switch is mediated by both the histone deacetylase Rpd3 and the Gcn5p/SAGA acetyltransferase. Our findings reveal a striking specificity for histone acetylation in promoting pathways that generate acetyl-CoA for oxidation when intracellular acetyl-CoA is limiting .
Project description:The gut microbiota influences host epigenetics by fermenting dietary fiber into butyrate. Although butyrate could promote histone acetylation by inhibiting histone deacetylases, it may also undergo oxidation to acetyl-CoA, a necessary cofactor for histone acetyltransferases. Here, we find that epithelial cells from germ-free mice harbor a loss of histone H4 acetylation across the genome except at promoter regions. Using stable isotope tracing in vivo with 13C-labeled fiber, we demonstrate that the microbiota supplies carbon for histone acetylation. Subsequent metabolomic profiling revealed hundreds of labeled molecules and supported a microbial contribution to host fatty acid metabolism, which declined in response to colitis and correlated with reduced expression of genes involved in fatty acid oxidation. These results illuminate the flow of carbon from the diet to the host via the microbiota, disruptions to which may affect energy homeostasis in the distal gut and contribute to the development of colitis.