Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508-000, Brazil; Department of Biology, New York University, New York, NY 10003, USA.
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508-000, Brazil.
Biochim Biophys Acta Gen Subj. 2022 Dec;1866(12):130238. doi: 10.1016/j.bbagen.2022.130238. Epub 2022 Aug 28.
The Hippo pathway plays central roles in relaying mechanical signals during development and tumorigenesis, but how the proteostasis of the Hippo kinase MST2 is regulated remains unknown. Here, we found that chemical inhibition of proteasomal proteolysis resulted in increased levels of MST2 in human breast epithelial cells. MST2 binds SCF E3 ubiquitin ligase and silencing βTrCP resulted in MST2 accumulation. Site-directed mutagenesis combined with computational molecular dynamics studies revealed that βTrCP binds MST2 via a non-canonical degradation motif. Additionally, stiffer extracellular matrix, as well as hyperactivation of integrins resulted in enhanced MST2 degradation mediated by integrin-linked kinase (ILK) and actomyosin stress fibers. Our study uncovers the underlying biochemical mechanisms controlling MST2 degradation and underscores how alterations in the microenvironment rigidity regulate the proteostasis of a central Hippo pathway component.
Hippo 通路在发育和肿瘤发生过程中传递机械信号方面发挥着核心作用，但 Hippo 激酶 MST2 的蛋白质稳定是如何调节的仍不清楚。在这里，我们发现蛋白酶体蛋白酶抑制化学物质导致人乳腺上皮细胞中 MST2 水平升高。MST2 结合 SCF E3 泛素连接酶，沉默 βTrCP 导致 MST2 积累。定点突变结合计算分子动力学研究表明，βTrCP 通过非典型降解基序与 MST2 结合。此外，细胞外基质变硬以及整合素过度激活导致肌球蛋白相关的应力纤维介导的 MST2 降解增强。我们的研究揭示了控制 MST2 降解的潜在生化机制，并强调了微环境刚性的改变如何调节 Hippo 通路核心成分的蛋白质稳定性。
