Regulation of ADP-ribosylation factor

ADP-核糖基化因子的调节

• 批准号: 7337945
• 负责人: Paul A Randazzo
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7337945
• 关键词: Regulation; ADP; ribosylation; factor

Coordinated membrane and actin remodeling are integral to a number of cellular functions, including (i) cell movement, (ii) endocytosis and exocytosis, and (iii) mitosis and are central to pathological processes such as tumor cell invasion and metastasis. A number of signaling molecules that control either or both membrane and actin remodeling include phosphoinositides, Arf family GTP-binding proteins and Rho family GTP-binding proteins. The main objective of the work in our laboratory is to elucidate the mechanisms that regulate signals mediated by Arf family proteins. The work has led to the identification of a family of Arf GTPase-activating proteins, the AZAPs, that may integrate at least four signaling pathways, providing coordinated responses in membranes and actin necessary for complex cellular behaviors. The AZAPs are comprised of four subfamilies: ASAP1/2/3, ACAP1/2/3, AGAP1/2/3 and ARAP1/2/3. Studies with two general goals are being conducted. One emphasis of the laboratory is to examine specific molecular mechanisms by which Arf GAPs interact with Arf and regulate Arf function. In these studies, we will determine (i) the interfaces between Arfs and GAPs; (ii) the interfaces between Arfs and coat proteins; (iii) the catalytic mechanism leading to GTP hydrolysis; (iv) mechanisms regulating GAP activity; and (v) functional interactions among Arfs, GAPs and Arf effectors including coat proteins. Studies to date have led us to propose (i) a new paradigm for the molecular mechanism by which Arf regulates cargo sorting and membrane trafficking, and (ii) an effector function for Arf GAPs of the AZAP family. Ongoing studies include testing these hypotheses and examining Arf GAPs as targets of signaling through tyrosine kinases and phosphoinositides. A second emphasis of the laboratory is an examination of the specific cellular sites of action of AZAP family members. This aim is closely related to the first. Using several strategies we have been determining the site of action for representative Arf GAPs. We have found specific membrane trafficking compartments regulated by some Arf GAPs. For instance, AGAP1 regulates AP-3 endosomes. We have also found that specific cytoskeletal structures are regulated by other Arf GAPs. For instance, ASAP1 regulates focal adhesions. We are currently examining the specific mechanisms that maintain and regulate Arf GAPs at specific sites, and exploring hypotheses about how the membrane trafficking sites may be related to the cytoskeletal sites. The most recent hypotheses that we are currently testing are (i) that Arf GAPs are in the Rho family signaling pathway with some Arf GAPs functioning as Rho effectors and (ii) Arf GAPs are targets of Src that are of crucial importance for the formation of podosomes and their pathologic analogs invadopia.

协调的膜和肌动蛋白重塑是许多细胞功能不可或缺的一部分，包括（i）细胞运动，（ii）胞吞作用和胞吐作用，以及（iii）有丝分裂，并且是肿瘤细胞侵袭和转移等病理过程的核心。许多控制膜和肌动蛋白重塑之一或两者的信号分子包括磷酸肌醇、Arf 家族 GTP 结合蛋白和 Rho 家族 GTP 结合蛋白。我们实验室工作的主要目标是阐明调节 Arf 家族蛋白介导的信号的机制。这项工作导致了 Arf GTP 酶激活蛋白家族 AZAP 的鉴定，该蛋白可能整合至少四个信号通路，在膜和肌动蛋白中提供复杂细胞行为所需的协调反应。 AZAP 由四个亚家族组成：ASAP1/2/3、ACAP1/2/3、AGAP1/2/3 和 ARAP1/2/3。正在进行的研究有两个总体目标。该实验室的重点之一是研究Arf GAPs与Arf相互作用并调节Arf功能的具体分子机制。在这些研究中，我们将确定 (i) Arfs 和 GAP 之间的接口； (ii) Arfs 和外壳蛋白之间的界面； (iii) 导致 GTP 水解的催化机制； (iv) 规范 GAP 活动的机制； (v) Arf、GAP 和 Arf 效应器（包括外壳蛋白）之间的功能相互作用。迄今为止的研究使我们提出了（i）Arf 调节货物分选和膜运输的分子机制的新范例，以及（ii）AZAP 家族 Arf GAP 的效应器功能。正在进行的研究包括测试这些假设并检查 Arf GAP 作为酪氨酸激酶和磷酸肌醇信号传导的靶标。该实验室的第二个重点是检查 AZAP 家族成员的特定细胞作用位点。这个目标与第一个目标密切相关。我们使用多种策略来确定代表性 Arf GAP 的作用位点。我们发现了一些 Arf GAP 调节的特定膜运输区室。例如，AGAP1 调节 AP-3 内体。我们还发现特定的细胞骨架结构受到其他 Arf GAP 的调节。例如，ASAP1 调节粘着斑。我们目前正在研究在特定位点维持和调节 Arf GAP 的具体机制，并探索关于膜运输位点如何与细胞骨架位点相关的假设。我们目前正在测试的最新假设是（i）Arf GAP 位于 Rho 家族信号通路中，其中一些 Arf GAP 作为 Rho 效应器发挥作用；（ii）Arf GAP 是 Src 的靶标，对于足小体及其病理类似物 invadopia 的形成至关重要。