The filopodial tip complex in adhesion, migration, and signaling

项目摘要/摘要 丝状伪足是质膜的指状延伸，允许细胞接触并与其相互作用。 神经生长、血管形成和癌细胞扩散等过程中的环境因素。 丝状柄顶端的一种鲜为人知的结构，即丝状柄尖端复合体，构成了 丝状肌动蛋白聚合、黏附和信号传递。我们对肌球蛋白-X(Myo10)的研究表明，它是一种 丝状末端复合体的主要成分，最近发现它在哺乳动物中具有重要作用 神经管闭合、眼球形成、血管发育和色素沉着的发育。一位患有 小眼炎(异常小的眼睛)最近被显示缺乏Myo10，强烈表明突变 Myo10基因的突变会导致人类的隐性遗传病。越来越多的论文也表明Myo10 是癌细胞侵袭、转移和分裂的关键蛋白，在主要的 人类癌症。这些和其他观察结果使Myo10成为抗癌研究和 因此，有必要确定Myo10和丝状末端复合体的基本细胞生物学功能。 虽然丝状尖端可以形成特殊的粘连部位，但它们缺乏局部粘连的核心成分。 几乎所有的丝状末端都含有Myo10，这是一种我们已经证明可以将肌动蛋白与β连接的蛋白质-整合素，Key 细胞黏附中的分子。因为尖端复合体的组装和组成以及它是如何随着 从延伸到缩回或粘连的转换是不理解的，我们将： 1)确定丝轴尖端复合体在起始、延伸、回缩和 粘附性这个目的将确定丝状伪足尖端复合体的组装途径和状态 丝状末端的核心成分包括Myo10、其可能的相互作用蛋白Vasp和封端蛋白。 2)确定有丝分裂回缩纤维顶端粘连的成分。虽然撤回 纤维在有丝分裂过程中起着锚定细胞的生物关键作用，几乎对 粘连在其顶端的组成。Myo10是已知的为数不多的定位于末端的蛋白质之一 回缩纤维，所以我们将利用它来研究这个知之甚少但却是细胞黏附的关键部位。 3)研究基侧丝状足的组成和功能。我们已经发现在 极化上皮细胞Myo10被定位于基底外侧表面的丝状足尖，而不是 同一细胞上的顶端微绒毛。因为Myo10提供了一种探针，可以探测到这种在很大程度上没有特征的 丝状伪足类，我们将用它来研究这些结构的基本细胞生物学。共同进行这项研究 将定义以Myo10和TIP复合体为标志的三种鲜为人知的结构的基本性质： 极化组基底外侧表面的丝状顶端粘连、回缩纤维粘连和丝状伪足 上皮细胞。

Project Summary/Abstract Filopodia are finger-like extensions of the plasma membrane that allow cells to contact and interact with their surroundings in processes such as nerve growth, blood vessel formation, and the spread of cancer cells. A poorly understood structure at the tips of filopodia, the filopodial tip complex, constitutes a key site of filopodial actin polymerization, adhesion, and signaling. Our research with myosin-X (Myo10) shows that it is a major component of the filopodial tip complex and recently revealed that it has important roles in mammalian development in neural tube closure, eye formation, blood vessel development, and pigmentation. A patient with microphthalmia (unusually small eyes) was recently shown to lack Myo10, strongly suggesting that mutations in Myo10 can cause recessive genetic disease in humans. A growing number of papers also show that Myo10 is a key protein in the invasion, metastasis, and division of cancer cells and is frequently upregulated in major human cancers. These and other observations make Myo10 an attractive target for anticancer research and make it essential to determine the fundamental cell biological functions of Myo10 and filopodial tip complex. Although filopodial tips can form specialized sites of adhesion, they lack core components of focal adhesions. Virtually all filopodial tips contain Myo10, a protein that we have shown can link actin to β-integrins, key molecules in cell adhesion. Because the assembly and composition of the tip complex and how it changes as it converts from extension to retraction or adhesion is not understood, we will: 1) Determine the composition of the filopodial tip complex during initiation, extension, retraction, and adhesion This aim will define the assembly pathway and states of the filopodia tip complex with respect to core filopodial tip components including Myo10, its putative interactor VASP, and capping protein. 2) Define the composition of the adhesions at the tips of mitotic retraction fibers. Although retraction fibers have the biologically crucial role of anchoring cells during mitosis, almost nothing is known about the composition of the adhesions at their tips. Myo10 is one of the few proteins known to localize to the tips of retraction fibers, so we will use it to investigate this poorly understood, but key site of cell adhesion. 3) Investigate the composition and functions of basolateral filopodia. We have discovered that in polarized epithelial cells Myo10 is targeted to the tips of filopodia on the basolateral surface rather than the apical microvilli on the same cells. Because Myo10 provides a probe for the tips of this largely uncharacterized class of filopodia, we will use it to investigate the basic cell biology of these structures. Together this research will define the basic properties of three poorly understood structure marked by Myo10 and the tip complex: filopodial tip adhesions, retraction fiber adhesions, and the filopodia on the basolateral surfaces of polarized epithelial cells.