Cellular Regulation of a Myosin II Heavy Chain Kinase

肌球蛋白 II 重链激酶的细胞调节

• 批准号: 7127591
• 负责人: PAUL A STEIMLE
• 金额: $ 20.93万
• 依托单位: UNIVERSITY OF NORTH CAROLINA GREENSBORO
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7127591
• 关键词: Dictyostelium; actins; binding proteins; cell cycle; cell migration; cell morphology; enzyme activity; enzyme mechanism; gene deletion mutation; gene induction /repression; microorganism culture; molecular assembly /self assembly; myosins; phosphorylation; protein isoforms; protein kinase; protein protein interaction; protein purification; protozoal genetics

DESCRIPTION (provided by applicant): The broad aim of the studies described in this AREA renewal proposal is to gain insight into the complex signaling events leading to myosin II filament assembly and localized contraction in a nonmuscle cell context. Critical cellular events, such as cell division and cell locomotion, rely on the correct localization and assembly of myosin II bipolar filaments within the cell; however, the signaling pathways regulating myosin II assembly are poorly understood. Studies in the social amoeba Dictyostelium have established that myosin II bipolar filament disassembly is driven by the phosphorylation of the myosin II heavy chain (MHC) "tail" region by three structurally-related MHC kinases - MHCK A, B, and C. The functional consequence of the filament to monomer transition is the inactivation of myosin ll-mediated contraction. Despite the redundancy in their catalytic activities, recent studies indicate that the MHCK A, B, and C enzymes play different roles in regulating myosin II disassembly in different cellular contexts. MHCK A is the most extensively-studied of the MHC kinases. Recent studies, conducted by undergraduate and Master's students in my lab, have revealed that F-actin is a potent activator of MHCK A catalytic activity. These studies also led to the novel discovery that the coiled-coil domain of MHCK A bundles actin filaments. In contrast to MHCK A, there is essentially no information about the structure-function relationships that define the activities of the MHCK B and C enzymes. Thus, the following specific questions will be addressed: 1) What are the actin-binding properties of the full-length MHCK A protein? 2) Do the subdomains of MHCK B and MHCK C play a role in targeting myosin II disassembly in the cell? 3) How do the MHCK B and MHCK C subdomains contribute to the kinase activities of these enzymes? The studies described here are necessary for identifying which properties of the MHCKs might be targeted by signals that lead to very specific changes in Dictyostelium cell shape. In a broader context, our studies provide an opportunity to identify how myosin ll-mediated cellular activities (i.e. cytokinesis and cellular migration) can be regulated in a nonmuscle cell context, and by extension, how these processes can go awry in cancer cells exhibiting uncontrolled cell division and metastasis. Moreover, the studies proposed here will be important for understanding the basic mechanisms by which cellular migration is achieved in other contexts such as wound healing, chemotaxis, and metazoan development. It is particularly noteworthy that the proposed studies are likely to contribute more directly to the knowledge of how defects in myosin II bipolar filament assembly can lead to the development of pathologies such as platelet malformation and kidney function defects, associated with a set of human genetic diseases, collectively called MYH9-related disorders.

描述（由申请人提供）：本AREA更新提案中描述的研究的广泛目的是深入了解导致非肌肉细胞中肌球蛋白II细丝组装和局部收缩的复杂信号事件。关键的细胞事件，如细胞分裂和细胞运动，依赖于正确的定位和组装的肌球蛋白II双极丝在细胞内，然而，调节肌球蛋白II组装的信号通路知之甚少。在社会性阿米巴Dictyosteoba中的研究已经证实，肌球蛋白II双极丝的分解是由三种结构相关的MHC激酶-- MHCK A、B和C--对肌球蛋白II重链（MHC）“尾部”区域的磷酸化驱动的。肌丝向单体转变的功能结果是肌球蛋白II介导的收缩失活。尽管它们的催化活性存在冗余，但最近的研究表明，MHCK A、B和C酶在不同的细胞环境中调节肌球蛋白II分解中发挥不同的作用。MHCK A是研究最广泛的MHC激酶。最近的研究，由本科生和硕士生在我的实验室进行的，已经揭示，F-肌动蛋白是一个有效的激活剂的MHCK A催化活性。这些研究还导致了新的发现，即MHCK A的卷曲螺旋结构域束肌动蛋白丝。与MHCK A相反，基本上没有关于定义MHCK B和C酶活性的结构-功能关系的信息。因此，以下具体问题将得到解决：1）什么是肌动蛋白结合的全长MHCK A蛋白的属性？2)MHCK B和MHCK C的亚结构域在靶向肌球蛋白II在细胞中的分解中发挥作用吗？3)MHCK B和MHCK C亚结构域如何对这些酶的激酶活性起作用？这里描述的研究是必要的，以确定哪些特性的MHCK可能是由信号，导致非常具体的变化，在网骨藻细胞形状的目标。在更广泛的背景下，我们的研究提供了一个机会，以确定如何肌球蛋白II介导的细胞活动（即胞质分裂和细胞迁移）可以在非肌肉细胞的情况下进行调节，并通过扩展，这些过程如何在癌细胞表现出不受控制的细胞分裂和转移出错。此外，这里提出的研究将是重要的理解细胞迁移的基本机制，实现在其他情况下，如伤口愈合，趋化性，和后生动物的发展。特别值得注意的是，拟议的研究可能更直接地有助于了解肌球蛋白II双极丝组装缺陷如何导致血小板畸形和肾功能缺陷等病理学的发展，这些病理学与一系列人类遗传疾病（统称为MYH 9相关疾病）相关。