The regulation of gene expression catalyzed by RNA polymerase II (Pol II) requires a host of accessory factors to ensure cell growth, differentiation, and survival under environmental stress. Here, using the auxin-inducible degradation (AID) system to study transcriptional activities of the bromodomain and extraterminal domain (BET) and super elongation complex (SEC) families, we found that the CDK9-containing BRD4 complex is required for the release of Pol II from promoter-proximal pausing for most genes, while the CDK9-containing SEC is required for activated transcription in the heat shock response. By using both the proteolysis targeting chimera (PROTAC) dBET6 and the AID system, we found that dBET6 treatment results in two major effects: increased pausing due to BRD4 loss, and reduced enhancer activity attributable to BRD2 loss. In the heat shock response, while auxin-mediated depletion of the AFF4 subunit of the SEC has a more severe defect than AFF1 depletion, simultaneous depletion of AFF1 and AFF4 leads to a stronger attenuation of the heat shock response, similar to treatment with the SEC inhibitor KL-1, suggesting a possible redundancy among SEC family members. This study highlights the usefulness of orthogonal acute depletion/inhibition strategies to identify distinct and redundant biological functions among Pol II elongation factor paralogs.

中文翻译：

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询问基因表达中 RNA 聚合酶 II 延伸因子功能的急性扰动策略

由 RNA 聚合酶 II (Pol II) 催化的基因表达调控需要大量辅助因子来确保细胞在环境压力下的生长、分化和存活。在这里，使用生长素诱导降解 (AID) 系统研究溴结构域和末端外结构域 (BET) 和超延伸复合物 (SEC) 家族的转录活性，我们发现含有 CDK9 的 BRD4 复合物是 Pol 的释放所必需的。 II 来自大多数基因的启动子近端暂停，而含有 CDK9 的 SEC 是热休克反应中激活转录所必需的。通过同时使用蛋白水解靶向嵌合体 (PROTAC) dBET6 和 AID 系统，我们发现 dBET6 治疗会产生两个主要影响：由于 BRD4 丢失导致暂停增加，以及由于 BRD2 丢失导致增强子活性降低。在热激反应中，虽然生长素介导的 SEC AFF4 亚基耗竭比 AFF1 耗竭具有更严重的缺陷，但 AFF1 和 AFF4 的同时耗竭导致热激反应更强的衰减，类似于用 SEC 处理KL-1 抑制剂，表明 SEC 家族成员之间可能存在冗余。这项研究强调了正交急性消耗/抑制策略在 Pol II 延伸因子旁系同源物中识别不同和冗余的生物学功能的有用性。表明 SEC 家族成员之间可能存在冗余。这项研究强调了正交急性消耗/抑制策略在 Pol II 延伸因子旁系同源物中识别不同和冗余的生物学功能的有用性。表明 SEC 家族成员之间可能存在冗余。这项研究强调了正交急性消耗/抑制策略在 Pol II 延伸因子旁系同源物中识别不同和冗余的生物学功能的有用性。