EGF-induced MAPK Signaling Inhibits Hemidesmosome Formation through Phosphorylation of the Integrin β4
EGF-induced MAPK Signaling Inhibits Hemidesmosome Formation through Phosphorylation of the Integrin β4
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DOI：
10.1074/jbc.m110.138818
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发表时间：
2010-11-26
影响因子：
4.8
通讯作者：
Sonnenberg, Arnoud
中科院分区：
文献类型：
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作者：
Frijns, Evelyne;Sachs, Norman;Sonnenberg, Arnoud
角质形成细胞的迁移需要半桥粒(HDs)的调节和动态周转。我们和其他人之前已经在整合素β4细胞质结构域上发现了三个丝氨酸残基，它们在HD拆解的调节中发挥了关键作用。在这项研究中，我们发现在角质形成细胞中只有两个残基(Ser-1356和Ser-1364)在PMA或EGF刺激后被磷酸化。此外，与以往的体外研究相比，我们发现PMA和EGF刺激的β4的磷酸化不是由PKC介导的，而是由ERK1/2及其下游效应激酶p90RSK1/2介导的。EGF刺激的β4的磷酸化促进角质形成细胞的迁移，并减少稳定的HDs的数量。此外，β4中的两个丝氨酸突变为模拟磷酸的天冬氨酸，减少了其与细胞骨架连接蛋白plectin的相互作用，以及α6β4介导的对层粘连蛋白-332的黏附强度。在有丝分裂细胞圆形过程中，当整个细胞-底物面积减少，HDs数量减少时，β4仅被一种独特的、但尚未鉴定的激酶在Ser-1356上磷酸化。总体而言，这些数据表明β4磷酸化残基Ser-1356和Ser-1364在HDs的形成和/或稳定性中发挥着重要作用。
Migration of keratinocytes requires a regulated and dynamic turnover of hemidesmosomes (HDs). We and others have previously identified three serine residues on the integrin beta 4 cytoplasmic domain that play a critical role in the regulation of HD disassembly. In this study we show that only two of these residues (Ser-1356 and Ser-1364) are phosphorylated in keratinocytes after stimulation with either PMA or EGF. Furthermore, in direct contrast to previous studies performed in vitro, we found that the PMA- and EGF-stimulated phosphorylation of beta 4 is not mediated by PKC, but by ERK1/2 and its downstream effector kinase p90RSK1/2. EGF-stimulated phosphorylation of beta 4 increased keratinocyte migration, and reduced the number of stable HDs. Furthermore, mutation of the two serines in beta 4 to phospho-mimicking aspartic acid decreased its interaction with the cytoskeletal linker protein plectin, as well as the strength of alpha 6 beta 4-mediated adhesion to laminin-332. During mitotic cell rounding, when the overall cell-substrate area is decreased and the number of HDs is reduced, beta 4 was only phosphorylated on Ser-1356 by a distinct, yet unidentified, kinase. Collectively, these data demonstrate an important role of beta 4 phosphorylation on residues Ser-1356 and Ser-1364 in the formation and/or stability of HDs.