Project description:Our studies indicate that glucose and acetate can regulate histone acetylation by altering the acetyl-CoA concentrations in the cell. The purpose of this study was to to determine whether specific gene sets correlated with acetyl-CoA availability. We conclude that 10% of glucose-regulated genes are acetyl-CoA regulated genes (genes suppressed or induced by low glucose and reversed by acetate). Acetate usually regulated gene expression in the same direction as glucose, suggesting that acetyl-CoA is a key mediator of glucose-dependent gene expression.
Project description:Our studies indicate that glucose and acetate can regulate histone acetylation by altering the acetyl-CoA concentrations in the cell. The purpose of this study was to to determine whether specific gene sets correlated with acetyl-CoA availability. We conclude that 10% of glucose-regulated genes are acetyl-CoA regulated genes (genes suppressed or induced by low glucose and reversed by acetate). Acetate usually regulated gene expression in the same direction as glucose, suggesting that acetyl-CoA is a key mediator of glucose-dependent gene expression. The experiments were performed in quadruplicates for each condition with a total of 12 samples
Project description:Histone acetylation, a post-translational modification associated with transcriptional activation, is governed by nuclear acetyl-CoA pools that can vary depending on the metabolic state of the cell. The metabolic enzyme acetyl-CoA synthetase 2 (ACSS2) is proposed to regulate nuclear acetyl-CoA levels, using local acetate to produce acetyl-CoA that is utilized for histone acetylation. We hypothesize that during gene activation, a local transfer of intact acetate occurs between histones to upregulate transcription via sequential action of epigenetic and metabolic enzymes. Here we present converging lines of evidence in support of this acetate transfer to serve rapid gene induction. Using stable isotope labeling, we detect local transfer of intact acetate between histone acetylation sites both in vitro using purified mammalian enzymes and in vivo using quiescence exit in Saccharomyces cerevisiae as a change-of-state model. We delineate the enzymatic components required for this transfer mechanism, finding that ACSS2, histone deacetylase and histone acetyltransferase enzymes are necessary for efficient acetyl-group transfer in vitro. We show that Acs2, the yeast orthologue of ACSS2, is recruited to the genome during quiescence exit, and observe dynamic changes of histone acetylation in the vicinity of Acs2 peaks in vivo. Strikingly, we find that Acs2 is preferentially associated with the most upregulated growth genes, suggesting that acetyl-group transfer might play an important role in increased gene expression. Overall, our data reveal direct transfer of acetate between histone lysine residues to facilitate rapid transcriptional induction, an exchange that may be critical during metabolic alterations and changes in nutrient availability.
Project description:Microbially-mediated uranium bioremediation has been demonstrated in uranium contaminated aquifers when acetate was artificially supplied and growth of the natural population of Geobacteraceae was stimulated. In order to mimic the environmental response to acetate, steady-state cells of G. sulfureducens were cultured in chemostats under conditions of either 1) acetate as the sole electron donor and limiting factor and fumarate as the sole electron acceptor or 2) acetate was supplied in excess with fumarate as sole electron acceptor and limiting factor. In silico fluxome modeling and transcriptome analysis were used as tools for investigating the cell response to the acetate availability. For global gene expression profiling, a DNA microarray of the complete G. sulfurreducens genome was used. Statistically significant results were obtained from two-color, dye swap hybridizations produced from a total of three biological replicates. Eight technical replicates were tested from two of the biological replicates and six technical replicates were tested from the third biological replicate. Major findings from this study are given as follows. The in silico model successfully predicted a higher TCA-cycle flux (ca. 2-fold) under acetate-excess conditions, suggesting that catabolism of acetate is favored with respect to anabolism, and thus more electrons are available for metal reduction. Transcriptome analyses offered a comprehensive picture of the regulation points subjected to the acetate availability. Under acetate-excess conditions, acetate transporters in the G. sulfurreducens genome were down-regulated. In addition the oxidation-related acetyl-CoA transferase was up-regulated approximately three-fold and the assimilatory-related acetate kinase was down-regulated approximately two-fold, respectively, indicating that the transcriptional regulation of acetate activation may be the key point for coping with the excess of acetate and increasing the TCA flux. The level of transcription for 10 c-type cytochromes was significantly increased in cells cultured with an excess of acetate. OmcS, an outer-membrane cytochrome which actively participates in electron transfer to Fe(III)-oxides and graphite electrodes from fuel cells, showed one of the highest fold increases in transcription. The integration of in silico modeling and genome-wide analysis shows for first time how G. sulffureducens adapts its metabolic flux and transcriptional network for optimizing the use of acetate as an electron donor for exocellular respiration instead of for use as a carbon source for biomass production. Keywords: Geobacter, gene expression, acetate limitation, fumarate limitation
Project description:Acetate metabolism is an important metabolic pathway in many types of cancers and is primarily controlled by acetyl-CoA synthetase 2 (ACSS2), an enzyme that catalyzes the conversion of acetate to acetyl-CoA. However, the consequences of inhibiting tumor acetate metabolism on the tumor microenvironment and anti-tumor immunity are unknown. Herein we demonstrate that the growth of ACSS2 deficient triple negative breast cancer is severely impaired when host immunity is intact and, in many instances, ACSS2 deficient tumors are fully cleared by the immune system. Pharmacological inhibition of ACSS2 using a potent small molecule inhibitor reproduces these effects and enhances the efficacy of standard of care chemotherapy for TNBC. Single cell RNA sequencing of vehicle versus ACSS2 inhibitor treated tumors indicates differentiation and activation of T cells suggesting a crosstalk between acetate metabolism and immune cells in the tumor microenvironment. Our data suggest that blocking ACSS2 and acetate metabolism in tumors increases the availability of acetate in the tumor microenvironment. Tumor infiltrating T cells can then use acetate as a fuel source due to the relatively high expression of acetyl-CoA synthetase 1 (ACSS1), which is impervious to ACSS2 inhibitors. In this manner, ACSS1-driven oxidation of acetate in T cells helps to metabolically bolster anti-tumor immune responses. Based on our findings, we propose a completely novel paradigm for ACSS2 inhibitors as metaboimmunomodulators that dually act as inhibitors of tumor cell metabolism and modulators of tumor immunity.
Project description:Acetate metabolism is an important metabolic pathway in many types of cancers and is primarily controlled by acetyl-CoA synthetase 2 (ACSS2), an enzyme that catalyzes the conversion of acetate to acetyl-CoA. However, the consequences of inhibiting tumor acetate metabolism on the tumor microenvironment and anti-tumor immunity are unknown. Herein we demonstrate that the growth of ACSS2 deficient triple negative breast cancer is severely impaired when host immunity is intact and, in many instances, ACSS2 deficient tumors are fully cleared by the immune system. Pharmacological inhibition of ACSS2 using a potent small molecule inhibitor reproduces these effects and enhances the efficacy of standard of care chemotherapy for TNBC. Single cell RNA sequencing of vehicle versus ACSS2 inhibitor treated tumors indicates differentiation and activation of T cells suggesting a crosstalk between acetate metabolism and immune cells in the tumor microenvironment. Our data suggest that blocking ACSS2 and acetate metabolism in tumors increases the availability of acetate in the tumor microenvironment. Tumor infiltrating T cells can then use acetate as a fuel source due to the relatively high expression of acetyl-CoA synthetase 1 (ACSS1), which is impervious to ACSS2 inhibitors. In this manner, ACSS1-driven oxidation of acetate in T cells helps to metabolically bolster anti-tumor immune responses. Based on our findings, we propose a completely novel paradigm for ACSS2 inhibitors as metaboimmunomodulators that dually act as inhibitors of tumor cell metabolism and modulators of tumor immunity.
Project description:In order to provide global information on gene expression during growth on C2 compounds, microarray analysis of M. extorquens AM1 cells was carried out, comparing ethylamine-grown cells to succinate-grown cells. This comparison has confirmed previous observations on the inducible nature of some of the enzymes involved in C2 metabolism, such as methylamine (and ethylamine) utilization system (mau), putative enzymes for converting acetaldehyde into acetate and acetyl-CoA, and enzymes of the ethylmalonyl-CoA pathway that has been proposed to operate for assimilation of acetyl-CoA into cell biomass.
Project description:In order to provide global information on gene expression during growth on C2 compounds, microarray analysis of M. extorquens AM1 cells was carried out, comparing ethylamine-grown cells to succinate-grown cells. This comparison has confirmed previous observations on the inducible nature of some of the enzymes involved in C2 metabolism, such as methylamine (and ethylamine) utilization system (mau), putative enzymes for converting acetaldehyde into acetate and acetyl-CoA, and enzymes of the ethylmalonyl-CoA pathway that has been proposed to operate for assimilation of acetyl-CoA into cell biomass. RNA from ethylamine-grown cells was compared to RNA from succinate-grown cells. Four biological replicates were carried out.
Project description:Histone acetylation, a post-translational modification associated with transcriptional activation, is governed by nuclear acetyl-CoA pools that can vary depending on the metabolic state of the cell. The metabolic enzyme acetyl-CoA synthetase 2 (ACSS2) is proposed to regulate nuclear acetyl-CoA levels, using local acetate to produce acetyl-CoA that is utilized for histone acetylation. We hypothesize that during gene activation, a local transfer of intact acetate occurs between histones to upregulate transcription via sequential action of epigenetic and metabolic enzymes. Here we present converging lines of evidence in support of this acetate transfer to serve rapid gene induction. Using stable isotope labeling, we detect local transfer of intact acetate between histone acetylation sites both in vitro using purified mammalian enzymes and in vivo using quiescence exit in Saccharomyces cerevisiae as a change-of-state model. We delineate the enzymatic components required for this transfer mechanism, finding that ACSS2, histone deacetylase and histone acetyltransferase enzymes are necessary for efficient acetyl-group transfer in vitro. We show that Acs2, the yeast orthologue of ACSS2, is recruited to the genome during quiescence exit, and observe dynamic changes of histone acetylation in the vicinity of Acs2 peaks in vivo. Strikingly, we find that Acs2 is preferentially associated with the most upregulated growth genes, suggesting that acetyl-group transfer might play an important role in increased gene expression. Overall, our data reveal direct transfer of acetate between histone lysine residues to facilitate rapid transcriptional induction, an exchange that may be critical during metabolic alterations and changes in nutrient availability.