CYTOSKELETON/MEMBRANE INTERACTIONS

细胞运动性和基于肌动蛋白的膜骨架的动态变化 发生在免疫细胞功能，神经元生长，伤口愈合， 以及细胞转化为浸润性癌症。尽管这些 这种变化被认为涉及到蛋白质在 肌动蛋白-膜界面，相关的相互作用蛋白在很大程度上 未知。拟议的研究将继续描述 阿米巴细胞中的膜骨架，例如未激活的细胞 嗜中性粒细胞和扁茎网囊线虫。尽管这些细胞缺乏稳定的 附着在其他细胞或细胞外基质上，它们的膜 包含负责空间和时间的细胞骨架连接 细胞形状的控制和/或细胞内反应的调节 细胞外信号。这些‘阿米巴’膜骨架似乎 在结构上与膜骨架不同，膜骨架具有 细胞锚定的位置。两种膜相关肌动蛋白结合 将对蛋白质进行研究：(A)提供 细胞表面和肌动蛋白细胞骨架之间的直接连接， 和(B)外周膜蛋白，可从 细胞质到膜骨架，在那里它们可以调节组装 或膜相关肌动蛋白细丝的稳定性。具体目标 建议的研究的主要内容是：(1)产生突变细胞系 目前正在进行的功能分析，Dictyostelisponticlin，第一个 完整的膜蛋白直接与肌动蛋白结合，并且唯一 具有肌动蛋白成核活性的完整膜蛋白； (2)确定甘油二酯调节的分子机制 提纯的网柄网柄菌肌动蛋白成核活性的提高 质膜；以及(3)确定膜相关肌动蛋白是否- 中性粒细胞和宫颈癌细胞中发现的结合蛋白 在结构上或功能上与黄连蛋白相似。这项研究 将有助于更好地理解所涉及的分子机制 在伪足类形成和稳定方面，在区域划分中 质膜，并在细胞表面或其他细胞脱离。 因此，这项研究将既增加我们对正常运动的认识 过程，并揭示潜在的病理条件下的缺陷， 包括出生缺陷、癌细胞转移和由以下因素引起的痴呆 携带艾滋病毒的巨噬细胞通过血脑屏障。

Dynamic changes in cell motility and in the actin-based membrane skeleton occur during immune cell functioning, neuronal outgrowth, wound healing, and the transformation of cells into invasive cancers. Although these changes are thought to involve rearrangements of the proteins at the actin-membrane interface, the relevant interacting proteins are largely unknown. The proposed research will continue the characterization of membrane skeletons in amoeboid cells, e.g., cells such as unactivated neutrophils and Dictyostelium amoebae. Although these cells lack stable attachments to other cells or to extracellular matrices, their membranes contain cytoskeletal linkages responsible for the spatial and temporal control of cell shape and/or the regulation of intracellular responses to extracellular signals. These 'amoeboid' membrane skeletons appear to be structurally distinct from the membrane skeletons that characterize sites of cell anchorage. Two types of membrane-associated actin-binding proteins will be investigated: (a) transmembrane proteins that provide direct connections between the cell surface and the actin cytoskeleton, and (b) peripheral membrane proteins that can be recruited from the cytoplasm to the membrane skeleton where they may regulate the assembly or stability of membrane-associated actin filaments. The specific aims of the proposed research are: (1) to generate mutant cell lines for ongoing functional analyses of Dictyostelium ponticulin, the first integral membrane protein shown to bind directly to actin and the only integral membrane protein with demonstrated actin nucleation activity; (2) to determine the molecular mechanism by which diacylglycerols mediate increases in the actin nucleation activity of purified Dictyostelium plasma membranes; and (3) to ascertain whether membrane-associated actin- binding proteins identified in neutrophils and cervical carcinoma cells are structurally or functionally similar to ponticulin. This research will lead to a better understanding of the molecular mechanisms involved in pseudopod formation and stabilization, in the regionalization of the plasma membrane, and in cell detachment from surfaces or other cells. This research thus will both increase our knowledge of normal motile processes and shed light on defects underlying pathological conditions, including birth defects, cancer cell metastasis, and dementia caused by transit of HIV-laden macrophages across the blood-brain barrier.