NatB Domain-Containing CRA-1 Antagonizes Hydrolase ACER-1 Linking Acetyl-CoA Metabolism to the Initiation of Recombination during C. elegans Meiosis

The formation of DNA double-strand breaks (DSBs) must take place during meiosis to ensure the formation of crossovers, which are required for accurate chromosome segregation, therefore avoiding aneuploidy. However, DSB formation must be tightly regulated to maintain genomic integrity. How this regulation operates in the context of different chromatin architectures and accessibility, and how it is linked to metabolic pathways, is not understood. We show here that global histone acetylation levels undergo changes throughout meiotic progression. Moreover, perturbations to global histone acetylation levels are accompanied by changes in the frequency of DSB formation in C. elegans. We provide evidence that the regulation of histone acetylation requires CRA-1, a NatB domain-containing protein homologous to human NAA25, which controls the levels of acetyl-Coenzyme A (acetyl-CoA) by antagonizing ACER-1, a previously unknown and conserved acetyl-CoA hydrolase. CRA-1 is in turn negatively regulated by XND-1, an AT-hook containing protein. We propose that this newly defined protein network links acetyl-CoA metabolism to meiotic DSB formation via modulation of global histone acetylation.     

Myc-dependent Mitochondrial Generation of Acetyl-CoA Contributes to Fatty Acid Biosynthesis and Histone Acetylation during Cell Cycle Entry

Cell reprogramming from a quiescent to proliferative state requires coordinate activation of multiple -omic networks. These networks activate histones, increase cellular bioenergetics and the synthesis of macromolecules required for cell proliferation. However, mechanisms that coordinate the regulation of these interconnected networks are not fully understood. The oncogene c-Myc (Myc) activates cellular metabolism and global chromatin remodeling. Here we tested for an interconnection between Myc regulation of metabolism and acetylation of histones. Using [¹³C₆]glucose and a combination of GC/MS and LC/ESI tandem mass spectrometry, we determined the fractional incorporation of ¹³C-labeled 2-carbon fragments into the fatty acid palmitate, and acetyl-lysines at the N-terminal tail of histone H4 in myc^−/− and myc^+/+ Rat1A fibroblasts. Our data demonstrate that Myc increases mitochondrial synthesis of acetyl-CoA, as the de novo synthesis of ¹³C-labeled palmitate was increased 2-fold in Myc-expressing cells. Additionally, Myc induced a forty percent increase in ¹³C-labeled acetyl-CoA on H4-K16. This is linked to the capacity of Myc to increase mitochondrial production of acetyl-CoA, as we show that mitochondria provide 50% of the acetyl groups on H4-K16. These data point to a key role for Myc in directing the interconnection of -omic networks, and in particular, epigenetic modification of proteins in response to proliferative signals.     

Nuclear accumulation of pyruvate dehydrogenase alpha 1 promotes histone acetylation and is essential for zygotic genome activation in porcine embryos

Porcine zygotic genome activation (ZGA) occurs along with global epigenetic remodeling at the 4-cell stage. These processes are regulated by histone acetylation, which requires acetyl-coenzyme A (CoA). Pyruvate dehydrogenase complex (PDC) is a crucial enzyme in glucose metabolism that converts pyruvate into acetyl-CoA. In mammalian cells, acetyl-CoA is produced by pyruvate dehydrogenase alpha 1 (PDHA1) translocated into the nucleus in special conditions. To determine whether zygotic PDHA1 plays a critical role in promoting histone acetylation during ZGA, a CRISPR/Cas9 genome editing system using multiple guide RNAs was employed to generate a PDHA1-targeted parthenogenetic embryo model. Results of immunofluorescent staining showed that the nuclear accumulation of PDHA1 during ZGA was significantly inhibited by PDHA1 targeting. Meanwhile, the 4-cell arrest rate significantly increased at 72 h after activation, indicating impeded embryonic development. In addition, nuclear histone acetylation significantly decreased when PDHA1 was targeted, and quantitative PCR showed that expression of several zygotic genes was significantly decreased in the PDHA1-targeting group compared to the control group. Overexpression of PDHA1 recovered the nuclear PDHA1, H3K9Ac and H3K27Ac and EIF1A expression levels. Moreover, the 5-to-8-cell-stage embryo development rate was only partially rescued. In conclusion, expression of zygotic origin PDHA1 contributes to porcine ZGA by maintaining histone acetylation in porcine embryos.     

Impaired coenzyme A synthesis in fission yeast causes defective mitosis,quiescence-exit failure,histone hypoacetylation and fragile DNA

Biosynthesis of coenzyme A (CoA) requires a five-step process using pantothenate and cysteine in the fission yeast Schizosaccharomyces pombe. CoA contains a thiol (SH) group, which reacts with carboxylic acid to form thioesters, giving rise to acyl-activated CoAs such as acetyl-CoA. Acetyl-CoA is essential for energy metabolism and protein acetylation, and, in higher eukaryotes, for the production of neurotransmitters. We isolated a novel S. pombe temperature-sensitive strain ppc1-537 mutated in the catalytic region of phosphopantothenoylcysteine synthetase (designated Ppc1), which is essential for CoA synthesis. The mutant becomes auxotrophic to pantothenate at permissive temperature, displaying greatly decreased levels of CoA, acetyl-CoA and histone acetylation. Moreover, ppc1-537 mutant cells failed to restore proliferation from quiescence. Ppc1 is thus the product of a super-housekeeping gene. The ppc1-537 mutant showed combined synthetic lethal defects with five of six histone deacetylase mutants, whereas sir2 deletion exceptionally rescued the ppc1-537 phenotype. In synchronous cultures, ppc1-537 cells can proceed to the S phase, but lose viability during mitosis failing in sister centromere/kinetochore segregation and nuclear division. Additionally, double-strand break repair is defective in the ppc1-537 mutant, producing fragile broken DNA, probably owing to diminished histone acetylation. The CoA-supported metabolism thus controls the state of chromosome DNA.     

NDRG2对胶质瘤U87-MG细胞组蛋白乙酰化的影响及机制研究

目的:探讨NDRG2对胶质瘤U87-MG细胞组蛋白乙酰化的影响,从代谢组学角度明确其抑癌机制,为胶质瘤治疗提供新思路。方法:利用慢病毒介导的外源性NDRG2基因在胶质瘤U87-MG细胞株中过表达,并采用MTT检测其对胶质瘤U87-MG细胞增殖的影响,采用Western blot技术研究其对胶质瘤U87-MG细胞组蛋白乙酰化及AKT-ACLY通路磷酸化状态的影响,并使用酶联反应检测胞内乙酰辅酶A的水平。结果:NDRG2在胶质瘤U87-MG细胞中外源过表达可降低AKT及下游分子ACLY的磷酸化水平,减少胞内乙酰辅酶A的合成,抑制组蛋白乙酰化。结论:NDRG2可能通过抑制AKT通路,减少组蛋白乙酰化,进而抑制胶质瘤U87-MG细胞增殖。