E4F1 COORDINATES PYRUVATE METABOLISM AND THE ACTIVITY OF THE ELONGATOR COMPLEX TO ENSURE TRANSLATION FIDELITY DURING BRAIN DEVELOPMENT [Polysome-seq]

Pyruvate metabolism defects lead to severe neuropathies such as the Leigh syndrome (LS) but the molecular mechanisms underlying neuronal cell death remain poorly understood. Here, we unravel a connection between pyruvate metabolism and the regulation of the epitranscriptome that is relevant to LS pathogenesis. We identified the transcription factor E4F1 as a key coordinator of AcetylCoenzyme A (AcCoA) production by the pyruvate dehydrogenase complex (PDC) and its utilization as an essential co-factor by the Elongator complex to acetylate tRNAs at the wobble position uridine 34 (U34). E4F1-mediated direct transcriptional regulation of Dlat and Elp3, two genes encoding key subunits of the PDC and of the Elongator complex, respectively, ensured proper translation fidelity and cell survival in the central nervous system (CNS) during mouse embryonic development. Furthermore, analysis of PDH-deficient cells highlighted a crosstalk linking the PDC to ELP3 expression that is perturbed in LS patients. Polysome profiling of mRNA isolated from 14.5 mouse brains.丙酮酸代谢（pyruvate metabolism）缺陷可引发包括利氏综合征（Leigh syndrome, LS）在内的严重神经病变，但神经元细胞死亡的分子机制仍有待深入阐释。本研究揭示了一条与利氏综合征发病机制相关的丙酮酸代谢与表观转录组（epitranscriptome）调控之间的关联通路。我们鉴定出转录因子E4F1是丙酮酸脱氢酶复合物（pyruvate dehydrogenase complex, PDC）合成乙酰辅酶A（AcetylCoenzyme A, AcCoA）的关键调控因子，同时作为核心协调者介导延伸复合物（Elongator complex）以该物质作为必需辅因子，在尿苷34（uridine 34, U34）的摆动位点对转运RNA（transfer RNA, tRNAs）进行乙酰化修饰。E4F1对分别编码PDC与延伸复合物关键亚基的两个基因Dlat和Elp3的直接转录调控，保障了小鼠胚胎发育阶段中枢神经系统（central nervous system, CNS）内的正常翻译保真度与细胞存活。此外，对丙酮酸脱氢酶缺陷细胞的分析表明，PDC与ELP3表达之间的串扰通路在利氏综合征患者体内存在异常紊乱。本研究对14.5天龄小鼠脑组织中分离得到的mRNA开展了多聚核糖体谱分析（polysome profiling）。