The histone deacetylase SIRT6 modulates Transcriptional pausing

摘要 真核生物的基因组被包装成染色质，这限制了rna聚合酶的可及性。 在转录过程中。最近在后生动物系统中的发现表明，大部分转录 调节发生在聚合酶招募的下游，通过调节停顿和 早期伸长的效率(Adelman和Lis，2012)。尽管我们已经了解了一些分子 调节从启动子近端停顿逃逸的玩家，无论染色质可及性和 哪些染色质修饰剂调节这一过程，仍有待完全了解。值得注意的是，我们有 最近发现组蛋白去乙酰基酶SIRT6是胚胎分化的中心调节因子 代谢，调节关键发育和代谢基因的表达以适应营养 压力(Mostola vsky等人，2006；钟等人，2010；Etchegaray等人，2015)；此外，SIRT6行为 作为一种肿瘤抑制因子，抑制肿瘤代谢和Myc依赖的转录(Sebastian等人， 2012年；Kugel等人，2015年；Kugel等人，2016年)。这些研究表明，基因表达的微调 SIRT6是维持细胞内环境平衡的关键。在这个提案中，我们将测试创新的想法， SIRT6作用于聚合酶募集的下游，调节启动子近端的停顿，a 新的，以前未知的组蛋白脱乙酰基酶的调节机制。具体地说，我们将1) 在分子水平上确定SIRT6在转录延伸中的功能， 在生物化学方面，SIRT6是否使用定义的、完全重组的体外系统和 在显色模板中测试转录延伸的生化分析。3)确定 SIRT6在胚胎发育早期转录延伸中的生理学意义。 总体而言，我们的结果应该为转录调控的分子机制提供新的见解。 调节，特别是与早期发育和对代谢信号的适应性反应有关的调节，a 可能有助于治疗发育性疾病、代谢性疾病和癌症的知识。

ABSTRACT The eukaryotic genome is packaged into chromatin, which limits the accessibility of RNA polymerase during transcription. Recent finding in metazoan systems have revealed that much of the transcription regulation occurs downstream of recruitment of the polymerase, through modulation of pausing and the efficiency of early elongation (Adelman and Lis, 2012). Although we have learned some of the molecular players that modulate escape from promoter proximal pausing, whether chromatin accessibility and which chromatin modifiers modulate this process, remains to be fully understood. Remarkably, we have recently identified the histone deacetylase SIRT6 as a central regulator of embryonic differentiation and metabolism, modulating expression of key developmental and metabolic genes to adapt against nutrient stress (Mostoslavsky et al., 2006; Zhong et al., 2010; Etchegaray et al., 2015); furthermore, SIRT6 acts as a tumor suppressor, inhibiting cancer metabolism amd Myc-dependent transcription (Sebastian et al., 2012; Kugel et al., 2015; Kugel et al., 2016). These studies indicate that fine-tuning of gene expression by SIRT6 is key to maintain cellular homeostasis. In this proposal, we will test the innovative idea that SIRT6 acts downstream of recruitment of the polymerase to modulate promoter proximal pausing, a novel, previously unidentified mechanism of regulation for an histone deacetylase. Specifically, we will 1) Determine, at the molecular level, the function of SIRT6 in transcriptional elongation 2) Decipher, biochemically, whether SIRT6 controls elongation using defined, fully reconstituted in-vitro systems and biochemical assays to test transcriptional elongation in chromatinized templates. 3) Determine the physiological relevance for SIRT6 roles in transcriptional elongation during early embryonic development. Overall, our results should provide new insights into the molecular mechanisms of transcriptional regulation, in particular those related to early development and adaptive responses to metabolic cues, a knowledge that may inform treatment against developmental diseases, metabolic diseases and cancer.