PDF(Pubmed)
Abstract：
The type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family produces the critical lipid regulator phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in the plasma membrane (PM). Here, we investigated the potential role of PIP5Kγ, a PIP5K isoform, in the Hippo pathway. The ectopic expression of PIP5Kγ87 or PIP5Kγ90, two major PIP5Kγ splice variants, activated large tumor suppressor kinase 1 (LATS1) and inhibited Yes-associated protein (YAP), whereas PIP5Kγ knockdown yielded opposite effects. The regulatory effects of PIP5Kγ were dependent on its catalytic activity and the presence of Merlin and LATS1. PIP5Kγ knockdown weakened the restoration of YAP phosphorylation upon stimulation with epidermal growth factor or lysophosphatidic acid. We further found that PIP5Kγ90 bound to the Merlin\'s band 4.1/ezrin/radixin/moesin (FERM) domain, forming a complex with PI(4,5)P2 and LATS1 at the PM. Notably, PIP5Kγ90, but not its kinase-deficient mutant, potentiated Merlin-LATS1 interaction and recruited LATS1 to the PM. Consistently, PIP5Kγ knockdown or inhibitor (UNC3230) enhanced colony formation in carcinoma cell lines YAP-dependently. In addition, PIP5Kγ90 interacted with heat shock cognate 71-kDa protein (Hsc70), which also contributed to Hippo pathway activation. Collectively, our results suggest that PIP5Kγ regulates the Hippo-YAP pathway by forming a functional complex with Merlin and LATS1 at the PI(4,5)P2-rich PM and via interplay with Hsc70.
摘要：
I型磷脂酰肌醇4-磷酸5-激酶（PIP5K）家族在质膜（PM）中产生关键的脂质调节剂磷脂酰肌醇4,5-双磷酸（PI（4,5）P2）。这里,我们研究了PIP5Kγ的潜在作用，PIP5K同工型，在河马的道路上。两种主要的PIP5Kγ剪接变体PIP5Kγ87或PIP5Kγ90的异位表达，激活大肿瘤抑制激酶1（LATS1）并抑制Yes相关蛋白（YAP），而PIP5Kγ敲低产生相反的效果。PIP5Kγ的调节作用取决于其催化活性以及Merlin和LATS1的存在。在用表皮生长因子或溶血磷脂酸刺激时，PIP5Kγ敲除减弱了YAP磷酸化的恢复。我们进一步发现PIP5Kγ90与Merlin带4.1/ezrin/radixin/moesin（FERM）结构域结合，在PM处与PI(4,5)P2和LATS1形成络合物。值得注意的是,PIP5Kγ90，但不是其激酶缺陷型突变体，增强了Merlin-LATS1的相互作用，并将LATS1招募到PM。始终如一，PIP5Kγ敲低或抑制剂（UNC3230）依赖性地增强癌细胞系YAP中的集落形成。此外,PIP5Kγ90与热休克同源71kDa蛋白（Hsc70）相互作用，这也有助于河马途径的激活。总的来说，我们的结果表明，PIP5Kγ通过在富含PI（4,5）P2的PM处与Merlin和LATS1形成功能复合物并通过与Hsc70相互作用来调节Hippo-YAP途径。
