A.N. Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia.
Int J Mol Sci. 2021 Jul 27;22(15):8006. doi: 10.3390/ijms22158006.
Coupling glycolysis and mitochondrial tricarboxylic acid cycle, pyruvate dehydrogenase (PDH) complex (PDHC) is highly responsive to cellular demands through multiple mechanisms, including PDH phosphorylation. PDHC also produces acetyl-CoA for protein acetylation involved in circadian regulation of metabolism. Thiamine (vitamin B1) diphosphate (ThDP) is known to activate PDH as both coenzyme and inhibitor of the PDH inactivating kinases. Molecular mechanisms integrating the function of thiamine-dependent PDHC into general redox metabolism, underlie physiological fitness of a cell or an organism. Here, we characterize the daytime- and thiamine-dependent changes in the rat brain PDHC function, expression and phosphorylation, assessing their impact on protein acetylation and metabolic regulation. Morning administration of thiamine significantly downregulates both the PDH phosphorylation at Ser293 and SIRT3 protein level, the effects not observed upon the evening administration. This action of thiamine nullifies the daytime-dependent changes in the brain PDHC activity and mitochondrial acetylation, inducing diurnal difference in the cytosolic acetylation and acetylation of total brain proteins. Screening the daytime dependence of central metabolic enzymes and proteins of thiol/disulfide metabolism reveals that thiamine also cancels daily changes in the malate dehydrogenase activity, opposite to those of the PDHC activity. Correlation analysis indicates that thiamine abrogates the strong positive correlation between the total acetylation of the brain proteins and PDHC function. Simultaneously, thiamine heightens interplay between the expression of PDHC components and total acetylation or SIRT2 protein level. These thiamine effects on the brain acetylation system change metabolic impact of acetylation. The changes are exemplified by the thiamine enhancement of the SIRT2 correlations with metabolic enzymes and proteins of thiol-disulfide metabolism. Thus, we show the daytime- and thiamine-dependent changes in the function and phosphorylation of brain PDHC, contributing to regulation of the brain acetylation system and redox metabolism. The daytime-dependent action of thiamine on PDHC and SIRT3 may be of therapeutic significance in correcting perturbed diurnal regulation.
丙酮酸脱氢酶复合物（PDHC）通过多种机制与细胞需求高度耦联，包括 PDH 磷酸化。PDHC 还产生乙酰辅酶 A，用于参与代谢昼夜节律调节的蛋白质乙酰化。焦磷酸硫胺素（维生素 B1）是 PDH 的辅酶和 PDH 失活激酶的抑制剂，已知它可以激活 PDH。将依赖硫胺素的 PDHC 的功能整合到一般氧化还原代谢中的分子机制是细胞或生物体生理适应性的基础。在这里，我们描述了白天和硫胺素依赖性大鼠大脑 PDHC 功能、表达和磷酸化的变化，评估了它们对蛋白质乙酰化和代谢调节的影响。白天给予硫胺素可显著下调 PDH 在 Ser293 的磷酸化和 SIRT3 蛋白水平，而晚上给予硫胺素则没有观察到这种作用。硫胺素的这种作用消除了大脑 PDHC 活性和线粒体乙酰化的昼夜依赖性变化，导致细胞溶质乙酰化和大脑总蛋白乙酰化的昼夜差异。筛选中央代谢酶和硫醇/二硫键代谢的蛋白质的日间依赖性表明，硫胺素也会取消 PDHC 活性的日间变化，而不是与 PDHC 活性相反。相关分析表明，硫胺素消除了大脑蛋白总乙酰化与 PDHC 功能之间的强正相关。同时，硫胺素增强了 PDHC 成分的表达与总乙酰化或 SIRT2 蛋白水平之间的相互作用。这些硫胺素对大脑乙酰化系统的影响改变了乙酰化的代谢影响。硫胺素增强 SIRT2 与代谢酶和硫醇/二硫键代谢的蛋白质的相关性就是这种影响的例证。因此，我们展示了大脑 PDHC 的功能和磷酸化的昼夜依赖性变化，有助于调节大脑乙酰化系统和氧化还原代谢。硫胺素对 PDHC 和 SIRT3 的昼夜依赖性作用可能对纠正昼夜节律紊乱具有治疗意义。
