Cross-Phosphorylation and Interaction between Src/FAK and MAPKAP5/PRAK in Early Focal Adhesions Controls Cell Motility.
Cross-Phosphorylation and Interaction between Src/FAK and MAPKAP5/PRAK in Early Focal Adhesions Controls Cell Motility.
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发表时间：
2014-05
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通讯作者：
S. Dwyer;I. Gelman
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作者：
S. Dwyer;I. Gelman
P38调节和激活激酶（PRAK/MAPKAPK 5）是位于p38和ERK 3/4 MAP激酶途径下游的丝氨酸/苏氨酸激酶。PRAK在细胞生长、营养饥饿反应、细胞程序性死亡、衰老和运动等过程中发挥着重要作用。PRAK已显示在不同情况下促进和抑制细胞运动。PRAK的促运动功能主要归因于其磷酸化底物HSP 27下游发生的细胞骨架重排;然而，最近显示PRAK是黏着斑激酶（FAK）上游内皮细胞运动所需的。FAK沿着Src，通过粘着斑中底物的磷酸化作为运动性信号传导的介体发挥作用。在这里，我们表明，PRAK，最初确定为FAK底物在原位/激酶覆盖试验，是一个Src底物，磷酸化的PRAK定向局灶性粘连。没有发现PRAK的粘着斑定位影响细胞运动性，然而瞬时过表达PRAK抑制HeLa细胞的运动性。这种作用需要PRAK激酶活性，并通过Y861上的磷酸化损害FAK活化而进行。我们的研究首次证明PRAK受酪氨酸磷酸化调节，定位于粘着斑，与FAK/Src发生物理相互作用并使其磷酸化。此外，我们提供了一种新的机制，抑制运动下游的PRAK。
P38-regulated and activated kinase (PRAK/MAPKAPK5) is a serine/threonine kinase which lies downstream of the p38 and ERK3/4 MAP kinase pathways. PRAK plays diverse roles in the processes of cell growth, nutrient starvation response, programmed cell death, senescence and motility. PRAK has been shown to both promote and inhibit cell motility in different contexts. The pro-motility functions of PRAK are attributed mainly to cytoskeletal rearrangement occurring downstream of its phosphorylated substrate HSP27; however, it was recently shown that PRAK is required for motility in endothelial cells upstream of Focal adhesion kinase (FAK). Along with Src, FAK functions as a mediator of motility signaling through the phosphorylation of substrates in focal adhesions. Here, we show that PRAK, initially identified as a FAK substrate in an in situ/ kinase overlay assay, is a Src substrate, the phosphorylation of which directs PRAK to focal adhesions. Focal adhesion localization of PRAK was not found to affect cell motility, however transient over expression of PRAK inhibited motility in HeLa cells. This effect requires PRAK kinase activity and proceeds through an impairment of FAK activation via phosphorylation on Y861. Our studies demonstrate for the first time that PRAK is regulated by tyrosine phosphorylation, localizes to focal adhesions, and interacts physically with and can phosphorylate FAK/Src. Further we provide a novel mechanism for the inhibition of motility downstream of PRAK.