P68 and Ca-calmodulin interaction in cell migration

描述（由申请人提供）：细胞迁移是细胞在许多基本生物过程中的基本特征，如胚胎发生、组织发育、伤口愈合和免疫反应系统中淋巴细胞的迁移。控制这一重要细胞过程的分子机制被广泛研究。然而，尽管有大量的表征，一些重要的知识差距仍然存在，特别是关于关键角色钙钙调素（CaM）在细胞迁移过程中的功能作用。我们已经观察到p68-CaM相互作用是上皮细胞迁移所必需的。在细胞迁移刺激下，p68-CaM相互作用显著增强。与CaM结合导致p68从细胞核定位到细胞质。在迁移细胞中，p68和CaM共同定位于迁移边缘（板足或丝足）。破坏p68 atp酶活性的突变阻断了CaM在迁移细胞前沿的定位。p68-钙调蛋白融合蛋白的表达导致板叶基的形成和细胞形态的改变，并显著增加细胞的运动性。免疫纯化的p68-CaM融合蛋白在体外与细胞骨架微管相互作用。此外，来自p68 IQ基序的肽强烈抑制细胞迁移。结果，用IQ肽治疗荷瘤小鼠几乎完全消除了肿瘤转移。我们的观察结果表明，p68-CaM相互作用是调节细胞迁移的新参与者。本研究的目的是了解p68-CaM相互作用在细胞迁移过程中的作用。我们提出了三个具体的目标来研究功能

DESCRIPTION (provided by applicant): Cell migration is an essential characteristic of cells in numerous fundamental biological processes, such as embryogenesis, tissue development, wound healing, and migration of lymphocytes in the immune response system. The molecular mechanism that governs this important cellular process is extensively studied. However, despite intensive characterizations, several important knowledge gaps remain, especially regarding the functional role of the key player, Ca-calmodulin (CaM), in the cell migration process. We have observed that the p68-CaM interaction is necessary for epithelial cell migration. Upon cell migration stimulation, the p68-CaM interaction was substantially enhanced. Binding to CaM caused localization of p68 from the cell nucleus to the cytoplasm. In the migrating cells, p68 and CaM co-localized to the migration leading edges (lamellipodia or fillopodia). Mutations that abolished p68 ATPase activity blocked the localization of CaM to the leading edge of migrating cells. Expression of a p68-calmodulin fusion protein led to the formation of lamellipodium and cell morphological changes and dramatically increased cell motility. The immunopurified p68-CaM fusion protein interacted with the cytoskeleton microtubule in vitro. In addition, a peptide derived from p68 IQ motifs strongly inhibited cell migration. As a consequence, treatment of tumor bearing mouse with the IQ peptide almost completely abolished cancer metastasis. Our observations suggest that the p68-CaM interaction is a new player in regulating the cell migration. The goal of this proposed research project is to understand the role of the p68-CaM interaction in cell migration process. We propose three specific aims to investigate the functional significance of p68-CaM interaction in cell migration. In specific aim 1, we will elucidate the mechanism that regulates the p68-CaM interaction. We will test our hypothesis that cell migration signals trigger phosphorylation of p68, which subsequently lead to the p68-CaM interaction. In specific aim 2, we will unravel the function of p68 at migration leading edge. In specific aim 3, we plan to focus on addressing the molecular mechanism that governors the substrate selection of p68 in different cellular processes. We believe that our results will ultimately be applied to develop new strategies for diseases diagnosis/prognosis and treatments.