PAK蛋白激酶活力调控的分子机制

The p21-activated kinases (PAKs) are serine/threonine protein kinases defined by their interaction with the small G proteins, and are signal transducers central to many vital cellular processes. PAKs have been implicated in pathological conditions including cancer, makes them attractive therapeutic targets. Thus, there has been considerable interest in exploration the regulation mechanism of PAKs to facilitate the drug development. Here, we propose to unravel the molecular mechanism of the regulation of Group I PAKs, by means of structural and enzyme kinetic studies. Activation of PAKs relies on both the release of the auto-inhibition and the autophosphorylation of particular sites of PAKs. We will perform structural studies on full-length PAKs and the Caspase-3 cleaved PAK2-RD-KD complex, to investigate the structural basis of the dimerization of PAKs and of the autophosphorylation ability of Caspase-3 cleaved PAK2-RD-KD complex. In addition, we will conduct detailed enzyme kinetic studies on the Caspase-3 cleaved PAK2-RD-KD complex, to elucidate where the first active molecule comes from and how the autophosphorylation process proceeds to get all molecules activated. These results will greatly improve our understanding of the mechanism of PAKs regulation and may also shed new light on the drug development targeting PAKs.

P21-activated kinases（PAKs）是一类丝氨酸/苏氨酸蛋白激酶，它们通过磷酸化下游底物，在多种细胞活动中起着关键的调控作用，其调控异常与多种人类疾病相关，是药物研发的重要靶标。因此，对其活力调控机制的研究具有重要的理论意义及应用价值。本研究项目大力联合结构生物学和酶动力学两种研究手段，深入探索Group I PAK蛋白活力调控的结构基础以及分子机制。PAKs的激活过程与其自抑制作用的解除及自磷酸化反应密切相关。项目研究一方面拟通过结构生物学的方法，解析全长PAK蛋白和Caspase-3酶切后的PAK2-RD-CD复合物的晶体结构，探索其形成自抑制双体及具有自激活潜能的结构基础；另一方面拟采用酶动力学研究手段，详细研究PAK2-RD-CD复合物的自磷酸化分子机制，揭示其自激活过程的起始及放大机制。研究成果将极大地加深人们在该领域的认识，并促进相关药物的研发进程。