PO.MCB03.03 · 分子与细胞生物学
STK40与CDK7在癌症进展中对YAP活性的协同调控
Cooperative regulation of YAP activity by STK40 and CDK7 in cancer progression
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
Yes相关蛋白（YAP）是一种机械敏感性转录共激活因子，可驱动细胞增殖和肿瘤发生。我们此前鉴定出假激酶STK40是一种支架蛋白，可直接结合并在翻译后水平调控YAP，敲低STK40会降低YAP的丰度和核定位。在激素受体阳性乳腺癌中，对CDK4/6抑制剂的抵抗仍是一大挑战，我们合作研究中新出现的证据提示CDK7通过CDK7-RNAPII-YAP-CDK6轴在转录水平调控YAP，从而促成治疗抵抗。STK40和CDK7是独立发挥作用还是汇聚于共同机制尚不清楚。利用SAS细胞，我们发现敲低CDK7可降低胞质和胞核中的YAP蛋白水平，并降低核质比，而同时敲低CDK7和STK40则表型上与单独敲低CDK7一致。CDK7过表达可部分挽救STK40敲低所致的YAP耗竭，表明CDK7在同一调控通路中作用于STK40下游。邻近连接实验证实了STK40与YAP的直接相互作用。降低肌动球蛋白张力可使YAP重新定位至质膜，但这种重分布在STK40敲低时被消除。ROCK抑制可增强质膜处YAP Y357位点的磷酸化（这是核进入所必需的修饰），但在STK40耗竭的细胞中该磷酸化完全丧失，表明STK40是将YAP定位至质膜以启动机械转导驱动的核输入所必需的。相反，敲低CDK7并不阻止YAP的膜募集，而是导致YAP在核膜处积聚却无法进入细胞核，提示CDK7调控核转位所必需的下游步骤。综上，这些数据揭示了一种此前未被认识的STK40与CDK7调控机制，协同控制YAP的丰度和亚细胞分布。STK40将YAP导向质膜以进行Y357磷酸化，而CDK7则作为使张力依赖性核输入得以进行的关键检查点。该机制代表了YAP驱动型癌症（包括CDK4/6抑制剂抵抗的HR+乳腺癌）中一个潜在的治疗易感靶点。
查看英文原文 English abstract
Yes-associated protein (YAP) is a mechanosensitive transcriptional co-activatorthat drives cell proliferation and tumorigenesis. We previously identified thepseudokinase STK40 as a scaffold that directly binds and post-translationallyregulates YAP, with STK40 knockdown reducing YAP abundance and nuclearlocalization. In hormone receptor positive breast cancer, resistance to CDK4/6inhibitors remains a major challenge, and emerging evidence from ourcollaborative studies suggests that CDK7 transcriptionally regulates YAPthrough a CDK7-RNAPII-YAP-CDK6 axis contributing to therapeutic resistance.Whether STK40 and CDK7 function independently or converge on a sharedmechanism remains unknown. Using SAS cells, we found that CDK7knockdown reduced YAP protein levels in both cytosol and nucleus anddecreased the nuclear-to-cytosolic ratio, whereas dual CDK7 and STK40knockdown phenocopied CDK7 loss alone. CDK7 overexpression partiallyrescued YAP depletion caused by STK40 knockdown, indicating that CDK7acts downstream of STK40 in the same regulatory pathway. Proximity ligationassays confirmed a direct STK40 and YAP interaction. Reducing actomyosintension caused YAP to relocalize to the plasma membrane, but thisredistribution was abolished by STK40 knockdown. ROCK inhibition enhancedYAP Y357 phosphorylation at the plasma membrane, a modification requiredfor nuclear entry, yet this phosphorylation was completely lost in STK40-depleted cells, indicating that STK40 is required for positioning YAP at themembrane to initiate mechanotransduction driven nuclear import. In contrast,CDK7 knockdown did not prevent YAP membrane recruitment but caused YAPto accumulate at the nuclear envelope without entering the nucleus, suggestingthat CDK7 regulates a downstream step essential for nuclear translocation.Together, these data reveal a previously unrecognized STK40 and CDK7regulatory mechanism that cooperatively controls YAP abundance andsubcellular distribution. STK40 directs YAP to the plasma membrane for Y357phosphorylation, whereas CDK7 acts as a critical checkpoint enabling tension-dependent nuclear import. This mechanism represents a potential therapeuticvulnerability in YAP-driven cancers, including CDK4/6 inhibitor-resistant HR+breast cancer.
利益披露 Disclosure
P. Li, None..
Y. Chen, None..
F. Tsai, None.