Par-4: a new activator of myosin phosphatase.
Par-4: a new activator of myosin phosphatase.
复制标题
DOI：
10.1091/mbc.e09-08-0711
复制
发表时间：
2010-04-01
影响因子：
3.3
通讯作者：
Morgan KG
中科院分区：
文献类型：
--
作者：
Vetterkind S;Lee E;Sundberg E;Poythress RH;Tao TC;Preuss U;Morgan KG
我们在这里首次表明，促凋亡蛋白Par-4结合并激活肌球蛋白磷酸酶（MP）。在激动剂刺激期间，Par-4促进ZIPK靶向和MP的抑制性磷酸化，然而，Par-4的磷酸化是MP抑制所必需的。我们的模型将Par-4作为MP活动范围的放大器。肌球蛋白磷酸酶（MP）是肌球蛋白轻链（LC 20）磷酸化的关键调节因子，而LC 20磷酸化是运动、凋亡和平滑肌收缩性所必需的过程。虽然MP抑制研究得很好，但对MP激活知之甚少。我们最近发现，前列腺细胞凋亡反应（Par）-4调节血管平滑肌收缩。在这里，我们测试的假设，Par-4直接调节MP活性。我们表明，通过邻近连接试验，表面等离子体共振和免疫共沉淀，Par-4与MP，MYPT 1的靶向亚基相互作用。结合由MYPT 1和Par-4的亮氨酸拉链介导，并由Par-4磷酸化降低。Par-4的过表达导致免疫沉淀MP的磷酸酶活性增加，而内源性Par-4的小干扰RNA敲低显著降低MP活性并增加MYPT 1磷酸化。LC 20磷酸化测定证明Par-4的过表达降低LC 20磷酸化。相反，磷酸化位点突变体，而不是野生型Par-4，干扰拉链相互作用蛋白激酶（ZIPK）介导的MP抑制。我们从我们的结果中得出结论，Par-4通过“挂锁”模型进行操作，其中Par-4与MYPT 1的结合通过阻断进入抑制性磷酸化位点来激活MP，并且ZIPK对MYPT 1的抑制性磷酸化需要通过磷酸化和Par-4从MP复合物中的置换来“解锁”Par-4。
We show here for the first time that the pro-apoptotic protein Par-4 binds to and activates myosin phosphatase (MP). During agonist stimulation, Par-4 facilitates ZIPK targeting and inhibitory phosphorylation of MP, however, phosphorylation of Par-4 is required for MP inhibition. Our model presents Par-4 as an amplifier of the MP activity range. Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis, and smooth muscle contractility. Although MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis response (Par)-4 modulates vascular smooth muscle contractility. Here, we test the hypothesis that Par-4 regulates MP activity directly. We show, by proximity ligation assays, surface plasmon resonance and coimmunoprecipitation, that Par-4 interacts with the targeting subunit of MP, MYPT1. Binding is mediated by the leucine zippers of MYPT1 and Par-4 and reduced by Par-4 phosphorylation. Overexpression of Par-4 leads to increased phosphatase activity of immunoprecipitated MP, whereas small interfering RNA knockdown of endogenous Par-4 significantly decreases MP activity and increases MYPT1 phosphorylation. LC20 phosphorylation assays demonstrate that overexpression of Par-4 reduces LC20 phosphorylation. In contrast, a phosphorylation site mutant, but not wild-type Par-4, interferes with zipper-interacting protein kinase (ZIPK)-mediated MP inhibition. We conclude from our results Par-4 operates through a “padlock” model in which binding of Par-4 to MYPT1 activates MP by blocking access to the inhibitory phosphorylation sites, and inhibitory phosphorylation of MYPT1 by ZIPK requires “unlocking” of Par-4 by phosphorylation and displacement of Par-4 from the MP complex.
登录
查看更多内容
影响因子：
46.9
作者：
Fredriksson, S;Gullberg, M;Landegren, U
通讯作者：
Landegren, U
影响因子：
4.8
作者：
Cheema, SK;Mishra, SK;Lopez-Berestein, G
通讯作者：
Lopez-Berestein, G
影响因子：
11.4
作者：
Joshi, Jayashree;Fernandez-Marcos, Pablo J.;Diaz-Meco, Maria T.
通讯作者：
Diaz-Meco, Maria T.
影响因子：
64.8
作者：
BURGERING, BMT;COFFER, PJ
通讯作者：
COFFER, PJ
影响因子：
5.3
作者：
Gurumurthy, S;Goswami, A;Rangnekar, VM
通讯作者：
Rangnekar, VM