Filopodia in Leukocyte and Endothelial Cell Function

越来越多的证据表明，细长的以肌动蛋白为基础的延伸，称为丝足，在 炎症和血管生成的细胞生物学。白血球和白血球的最初接触 在白细胞滚动过程中，内皮细胞发生在丝状足状结构的顶端，内皮细胞 在血管生成过程中，“探路者”细胞似乎受到丝状伪足的引导。尽管有这些关键的作用， 白细胞和内皮细胞中的丝状伪足，丝状伪足伸展的分子机制， 粘附性和信号转导在很大程度上是未知的。我们发现肌球蛋白-X(Myo10)是 一个假定的丝足尖复合体，参与丝足的形成，并经历一种新的运动形式。 为我们研究这些问题提供了一个强有力的工具。因此，我们建议： 确定Myolo与整合素相互作用的功能后果。由于Myo10是一种 非常规肌球蛋白，其尾部包括可结合到整合素胞浆域的perm结构域， 我们将测试与这种马达蛋白的结合是否激活整合素。我们还将测试Myo10 结合白细胞特异性的β2整合素，以及补体介导的吞噬是否需要Myo10。 II.分析Myo10在白细胞和内皮细胞中的功能 使用siRNA和显性阴性的丝状突起、趋化和跨内皮细胞迁移 建造。虽然Myo10是在大多数脊椎动物细胞中表达的神话中的肌球蛋白和相关的 低等生物中的肌球蛋白是丝状足的形成、黏附和吞噬所必需的，几乎不需要。 了解这个肌球蛋白家族在白细胞和内皮细胞中的功能。 确定丝状末端复合体的基本生化特性和组成。就像 局灶性黏附，丝状末端复合体似乎作为细胞黏附、信号传递、 和肌动蛋白聚合，但目前对其分子组成和性质知之甚少 丝状顶端复合体。 这项工作与公共卫生有很大的关系，因为它将研究基础细胞生物学 炎症和细胞信号机制是心血管疾病和其他严重疾病的基础 人类健康问题。

Growing evidence indicates that the slender actin-based extensions known as filopodia play central roles in the cell biology underlying inflammation and angiogenesis. The initial contacts between leukocytes and endothelial cells during leukocyte rolling occur at the tips of filopodia-like structures and endothelial "pathfinder" cells appear to be guided by filopodia during angiogenesis. Despite these critical roles of filopodia in leukocytes and endothelial cells, the molecular mechanisms underlying filopodial extension, adhesion, and signaling are largely unknown. Our discovery that myosin-X (Myo10) is a core component of a putative filopodial tip complex, is involved in filopodia formation, and undergoes a novel form of motility in filopodia, gives us a powerful tool to investigate these questions. We therefore propose to: I. Determine the functional consequences of MyolO's interaction with integrins. Since Myo10 is an unconventional myosin whose tail includes a PERM domain that can binds to the cytoplasmic domains of pintegrins, we will test whether binding to this motor protein activates integrins. We will also test if Myo10 binds to the leukocyte specific beta2-integrins and if Myo10 is required for complement-mediated phagocytosis. II. Analyze the functions of Myo10 in leukocytes and endothelial cells in processes such as filopodial extension, chemotaxis, and transendothelial migration using siRNA and a dominant negative construct. Although Myo10 is the MyTH-FERM myosin expressed in most vertebrate cells and a related myosin in lower organisms is required for filopodia formation, adhesion, and phagocytosis, almost nothing is known about the functions of this family of myosins in leukocytes and endothelial cells. III. Define the basic biochemical properties and components of the filopodial tip complex. Like the focal adhesion, the filopodial tip complex appears to function as a specialized site of cell adhesion, signaling, and actin polymerization, but currently very little is known about the molecular components and properties of the filopodial tip complex. This work is of great relevance to public health because it will investigate the fundamental cell biological mechanisms of inflammation and cell signaling that underlie cardiovascular disease and other serious human health problems.