Project description:Differences in global levels of histone acetylation occur in normal and cancer cells, although the reason cells regulate these levels has remained unclear. Here we demonstrate a role for histone acetylation in regulating intracellular pH (pHi). As pHi decreases, histones are globally deacetylated by histone deacetylases (HDACs) and the released acetate anions are co-exported with protons out of the cell by monocarboxylate transporters (MCTs), preventing further reductions in pHi. Conversely, global histone acetylation increases at more alkaline pHi, such as when resting cells are induced to proliferate. Inhibition of HDACs or MCTs decreases acetate export and lowers pHi, particularly compromising pHi maintenance in acidic environments. Global deacetylation at low pH is reflected at a genomic level by decreased abundance and extensive redistribution of acetylation at promoters and intergenic regions. Thus acetylation of chromatin functions as a rheostat to regulate pHi with important implications for therapeutic use of HDAC inhibitors. To investigate the redistribution of H4K16ac throughout the genome upon treatment at pH 6.5
Project description:Acetylation of lysine residues is conserved across organisms and plays important roles in various cellular functions. Maintaining intracellular pH homeostasis is crucial for the survival of enteric bacteria in acidic gastric tract. However, it remains unkown whether bacteria can utilize reversible protein acetylation system to adapt to acidic environment. Here we demonstrate that the protein acetylation/deacetylation is critical for Salmonella Typhimurium to survive in acidic environment. We first used RNA-seq to analyze the transcriptome patterns under acid stress, and found that the transcriptional levels of genes involved in NAD+/NADH metabolism were significantly changed, leading to the increase of intracellular NAD+/NADH ratio. Moreover, acid stress down-regulated the transcriptional level of pat (encoding an acetyltranseferase) and genes encoding adenylate cyclase and cAMP-regulatory protein (CRP) which regulates pat positively. Acid signal also affects TCA cycle to promote the consumption of Ac-CoA, which reduced the donor of acetylation. Lowered acetylation level is not only bacterial’s response to acid stress, but also positively regulates the survival rate of S. Typhimurium. The deletion mutant of pat had more stable intracellular pH, which paralleled with higher survival rate after acid treatment compared with the wild type strain and deletion mutant of cobB. Our data suggest that bacteria can down-regulate protein acetylation level to prevent intracellular pH further falling in acid stress, and this work may provide a new perspective to understand the bacterial acid resistance mechanism. To use RNA-seq to analyze the transcriptome patterns under acid stress
Project description:Acetylation of lysine residues is conserved across organisms and plays important roles in various cellular functions. Maintaining intracellular pH homeostasis is crucial for the survival of enteric bacteria in acidic gastric tract. However, it remains unkown whether bacteria can utilize reversible protein acetylation system to adapt to acidic environment. Here we demonstrate that the protein acetylation/deacetylation is critical for Salmonella Typhimurium to survive in acidic environment. We first used RNA-seq to analyze the transcriptome patterns under acid stress, and found that the transcriptional levels of genes involved in NAD+/NADH metabolism were significantly changed, leading to the increase of intracellular NAD+/NADH ratio. Moreover, acid stress down-regulated the transcriptional level of pat (encoding an acetyltranseferase) and genes encoding adenylate cyclase and cAMP-regulatory protein (CRP) which regulates pat positively. Acid signal also affects TCA cycle to promote the consumption of Ac-CoA, which reduced the donor of acetylation. Lowered acetylation level is not only bacterial’s response to acid stress, but also positively regulates the survival rate of S. Typhimurium. The deletion mutant of pat had more stable intracellular pH, which paralleled with higher survival rate after acid treatment compared with the wild type strain and deletion mutant of cobB. Our data suggest that bacteria can down-regulate protein acetylation level to prevent intracellular pH further falling in acid stress, and this work may provide a new perspective to understand the bacterial acid resistance mechanism.
Project description:Differences in global levels of histone acetylation occur in normal and cancer cells, although the reason cells regulate these levels has remained unclear. Here we demonstrate a role for histone acetylation in regulating intracellular pH (pHi). As pHi decreases, histones are globally deacetylated by histone deacetylases (HDACs) and the released acetate anions are co-exported with protons out of the cell by monocarboxylate transporters (MCTs), preventing further reductions in pHi. Conversely, global histone acetylation increases at more alkaline pHi, such as when resting cells are induced to proliferate. Inhibition of HDACs or MCTs decreases acetate export and lowers pHi, particularly compromising pHi maintenance in acidic environments. Global deacetylation at low pH is reflected at a genomic level by decreased abundance and extensive redistribution of acetylation at promoters and intergenic regions. Thus acetylation of chromatin functions as a rheostat to regulate pHi with important implications for therapeutic use of HDAC inhibitors.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.