CYTOSKELETON/MEMBRANE INTERACTIONS

细胞运动和肌动蛋白膜骨架的动态变化 发生在免疫细胞功能，神经元生长，伤口愈合， 以及细胞转化为侵袭性癌症。 虽然这些 这些变化被认为涉及到蛋白质的重排， 肌动蛋白-膜界面，相关的相互作用蛋白主要是 未知 拟议的研究将继续表征 变形虫细胞中的膜骨架，例如，未激活的细胞 嗜中性粒细胞和变形网骨藻。虽然这些细胞缺乏稳定的 附着于其他细胞或细胞外基质， 包含负责空间和时间的细胞骨架连接 控制细胞形状和/或调节细胞内反应 细胞外信号。这些“变形虫”膜骨架似乎 在结构上不同于表征 细胞锚定的位置。两种类型的膜相关肌动蛋白结合 蛋白质将被研究：（a）跨膜蛋白， 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，其可以从所述细胞中募集， 细胞质到膜骨架，在那里它们可以调节组装 或膜相关肌动蛋白丝的稳定性。具体目标 研究的主要内容是：（1）建立突变细胞系， 正在进行的桥脑网骨桥蛋白的功能分析， 整合膜蛋白显示直接结合肌动蛋白和唯一 具有已证实的肌动蛋白成核活性的整合膜蛋白; (2)以确定二酰基甘油介导的分子机制， 增加纯化的网骨藻的肌动蛋白成核活性 （3）确定膜相关肌动蛋白是否 在中性粒细胞和宫颈癌细胞中鉴定的结合蛋白 在结构或功能上与脑桥蛋白相似。本研究 将使我们更好地理解 在伪足的形成和稳定方面， 质膜，以及细胞从表面或其他细胞脱离。 因此，这项研究将增加我们对正常运动的认识， 过程和揭示缺陷潜在的病理条件， 包括出生缺陷，癌细胞转移，以及 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.