Regulation of ADP-ribosylation factor

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）胞吞和胞吐，（iii）有丝分裂，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的信号分子包括磷酸肌苷、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的是阐明由Arf家族蛋白介导的信号调节机制。这项工作导致了Arf gtpase激活蛋白家族的鉴定，AZAPs可能整合了至少四种信号通路，在膜和肌动蛋白中提供复杂细胞行为所必需的协调反应。azap由四个亚家族组成：ASAP1/2/3、ACAP1/2/3、AGAP1/2/3和ARAP1/2/3。目前正在进行有两个总体目标的研究。实验室的一个重点是研究Arf gap与Arf相互作用并调节Arf功能的特定分子机制。在这些研究中，我们将确定(i) Arfs和GAPs之间的接口；（ii） Arfs和外壳蛋白之间的界面；（iii） GTP水解的催化机理；调节GAP活动的机制；(v) Arfs、gap和Arf效应物（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调节货物分拣和膜运输的分子机制的新范式，以及（ii） AZAP家族的Arf GAPs的效应函数。正在进行的研究包括验证这些假设，并检查Arf gap作为酪氨酸激酶和磷酸肌苷信号传导的靶点。实验室的第二个重点是AZAP家族成员的特定细胞作用位点的检查。这个目标与第一个目标密切相关。我们采用了几种策略，确定了具有代表性的Arf gap的行动地点。我们发现了由一些Arf gap调节的特定膜运输区室。例如，AGAP1调节AP-3核内体。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调节局灶粘连。我们目前正在研究维持和调节特定位点的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 GAPs位于Rho家族信号通路中，其中一些Arf GAPs作为Rho效应物起作用；（ii） Arf GAPs是Src的靶点，对于足质体及其病理类似物的形成至关重要。<BR><BR><BR><BR>Z01 BC 07365-03 LBC到LCO

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. <BR><BR>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. <BR><BR>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. <BR><BR><BR><BR>Z01 BC 07365-03 LBC to LCO