Role Of Intersectin Adaptor Protein In Regulation Of End

工作概述：我们的研究小组对交叉蛋白（ITSN）接头蛋白在调节信号转导级联反应中的作用感兴趣，特别是酪氨酸受体激酶（RTKs）。ITSN是一个不断增长的衔接蛋白家族的成员，该家族具有保守的Eps15同源性（EH）结构域以及额外的蛋白质识别基序。含eh蛋白在调节网格蛋白依赖的内吞作用中起着不可或缺的作用。ITSN由两个nh4末端EH结构域、一个CC区和5个串联Src同源3 （SH3）结构域组成。此外，ITSN还有一个更大的剪接变体ITSN- l，它具有编码Dbl同源（DH）结构域、Pleckstrin同源（PH）结构域和C2结构域的cooh末端扩展。DH结构域在ras样GTPases的Rho亚家族中起鸟嘌呤核苷酸交换因子（GEFs）的作用，包括Rho、Rac和Cdc42。这些结构域与PH结构域协同作用，PH结构域直接与脂质和膜相互作用。因此，ITSN-L可能参与调控Rho家族在神经系统中的激活。C2结构域结合磷脂膜、蛋白质或可溶性肌醇多磷酸，使用Ca+2依赖和Ca+2独立的机制。尽管各种实验都表明ITSN参与胞吞作用的调节，但我们现在已经证明ITSN激活了信号转导途径。过去十年的研究表明，内吞作用和有丝分裂信号之间存在联系。因此，我们的研究结果表明，ITSN可能是这两个细胞过程之间的一个可能的分子联系。我们目前的重点是了解ITSN激活信号通路的机制。ITSN的靶标之一是Elk-1转录因子。虽然Elk-1通常被认为是Ras-MAPK通路的靶点，但我们已经证明ITSN以MEK和mapk独立的方式激活Elk-1。因此，ITSN似乎刺激了一条不同于经典Ras-MAPK通路的通路来激活Elk-1。我们正在确定这一途径的性质。此外，我们想确定这种信号活动对ITSN功能的重要性。鉴于ITSN在调节RTK内吞作用中的作用，我们目前正在研究ITSN通过调节RTK内吞作用、再循环和降解来调节RTK功能的可能功能。

Summary of Work: Our group is interested in understanding the role of the Intersectin (ITSN) adaptor protein in regulating signal transduction cascades in general and receptor tyrosine kinases (RTKs) in particular. ITSN is a member of a growing family of adaptor proteins that possess conserved Eps15 homology (EH) domains as well as additional protein recognition motifs. EH-containing proteins play an integral role in regulating clathrin-dependent endocytosis. ITSN consists of two NH4-terminal EH domains, a coiled-coil (CC) region and 5 tandem Src homology 3 (SH3) domains. In addition, there is a larger splice variant of ITSN, termed ITSN-L, which possess a COOH-terminal extension encoding a Dbl homology (DH) domain, a Pleckstrin homology (PH) domain and a C2 domain . DH domains function as guanine nucleotide exchange factors (GEFs) for the Rho subfamily of Ras-like GTPases which include Rho, Rac and Cdc42. These domains function in concert with PH domains which direct interaction with lipids and membrane. Thus, ITSN-L may serve to regulate Rho family activation within the nervous system. C2 domains bind phospholipid membranes, proteins or soluble inositol polyphosphates using both Ca+2-dependent and -independent mechanisms. Although a variety of experiments have implicated ITSN in the regulation of endocytosis, we have now demonstrated that ITSN activates signal transduction pathways. Research over the past decade has suggested a link between endocytosis and mitogenic signaling. Thus, our findings suggest that ITSN may be one possible molecular link between these two cellular processes. Our current focus is on understanding the mechanism by which ITSN activates signaling pathways. One of the targets of ITSN is the Elk-1 transcription factor. Although Elk-1 is classically known as a target of the Ras-MAPK pathway, we have demonstrated that ITSN activates Elk-1 in a MEK and MAPK-independent manner. Thus, ITSN appears to stimulate a pathway distinct from the classic Ras-MAPK pathway in order to activate Elk-1. We are in the process of determining the nature of this pathway. In addition we want to determine the importance of this signaling activity for ITSN function. Given the role of ITSN in the regulation of endocytosis, we are currently examining the possible function of ITSN in modulating RTK function through regulation of RTK endocytosis, recycling and degradation.