INTRACELLULAR SIGNALS MEDIATING SMOOTH MUSCLE CELL MIGRATION

诱导血管平滑所需的细胞内机制 肌细胞对损伤的迁移和增殖反应较差， 明白 尽管有几种受体系统能够启动 平滑肌细胞迁移和增殖后的结合 配体（bFGF，PDGF和最近的NGF）特异性细胞内 这些受体酪氨酸激酶激活的途径， 血管平滑肌细胞还有待鉴定。 最近的研究 已经证明了一种新的生长 因子/受体系统，神经营养因子及其受体，trk 受体酪氨酸激酶和p75，在两者的中膜平滑肌细胞 大鼠和人主动脉以及培养的人和大鼠血管平滑肌中 细胞 此外，它们的表达在哺乳动物的发育过程中受到精密的调控。 血管再狭窄的发展，正如它们在 人动脉粥样硬化病变和在以下形成的新生内膜中 球囊损伤大鼠主动脉。 最后，神经营养素是有效的 血管平滑肌细胞迁移的介质， 与PDGF相似。 神经营养因子与trk的共表达 受体及其对平滑肌细胞迁移的作用表明， 这些生长因子在调节 平滑肌细胞血管损伤。 Trk是一种受体酪氨酸激酶，其已被证明可激活 神经元细胞中的细胞内信号传导途径的数量，例如 ras/MAP激酶途径、磷脂酶C（PLC-γ）和磷脂酰 肌醇3-OH激酶（P13-激酶）。 细胞内p75的作用机制 信号还没有被定义，虽然激活 鞘磷脂酶和随后的细胞内神经酰胺的释放 最近被几个实验室证实。 的总体目标 这项拨款提案是为了确定平滑肌的信号通路， 神经营养因子引起的细胞迁移 这些途径将是 与PDGF和bFGF受体激活的细胞相比， 这些途径是诱导血管平滑肌 肌细胞迁移 具体而言，我们打算：建立 血管平滑肌细胞系统表达trk受体，以及 参与启动血管平滑肌的其他受体酪氨酸激酶 使用基因转移技术的肌肉细胞迁移。 二.识别 受体后通路介导平滑肌细胞迁移， 表达trk、PDGF-β和FGF-1受体酪氨酸激酶的细胞。 不能激活特定信号酶的突变受体， 用于证实这些特定途径介导细胞迁移。 三.研究p75受体信号转导在神经营养因子- 介导的平滑肌细胞迁移。 这些研究涉及关键的 与格罗斯博士、哈贾尔博士、波梅兰茨博士和兰德博士的互动。

The intracellular mechanisms which are required to induce vascular smooth muscle cell migration and proliferation in response to injury are poorly understood. Although several receptor systems are capable of initiating smooth muscle cell migration and proliferation following the binding of ligand (bFGF, PDGF and most recently, NGF) the specific intracellular pathways which are activated by these receptor tyrosine kinases in vascular smooth muscle cells have yet to be characterized. Recent studies from our laboratory have demonstrated the expression of a novel growth factor/receptor system, the neurotrophins and their receptors, trk receptor tyrosine kinases and p75, in medial smooth muscle cells of both rat and human aorta and in cultured vascular human and rat smooth muscle cells. Moreover, their expression is exquisitely regulated during the development of vascular restenosis, as demonstrated by their expression in human atherosclerotic lesions and in the neointima which forms following balloon injury to the rat aorta. Finally, neurotrophins are potent mediators of vascular smooth muscle cell migration, in a response comparable to PDGF. The coexpression of the neurotrophins and trk receptors and their effect on smooth muscle cell migration suggests that these growth factors play an important role in regulating the response of smooth muscle cells to vascular injury. Trk is a receptor tyrosine kinase which has been shown to activate a number of intracellular signaling pathways in neuronal cells, such as the ras/MAP kinase pathway, phospholipase C (PLC-gamma) and phosphotidyl inositol 3-OH kinase (P13-kinase). The mechanisms of p75 intracellular signaling have not yet been defined, although an activation of sphingomyelinase and subsequent release of intracellular ceramide has recently been demonstrated by several laboratories. The overall aim of this grant proposal is to define the signaling pathways for smooth muscle cell migration in response to the neurotrophins. These pathways will be compared with those activated by the PDGF and bFGF receptors, to define those pathways which are required for the induction of vascular smooth muscle cell migration. Specifically, we intend to: I. Establish a vascular smooth muscle cell system to express trk receptors, as well as other receptor tyrosine kinases implicated in initiating vascular smooth muscle cell migration using gene transfer techniques. II. Identify the post-receptor pathways which mediate smooth muscle cell migration using cells which express trk, PDGF-beta and FGF-1 receptor tyrosine kinases. Mutant receptors, incapable of activating defined signaling enzymes, will be used to confirm that these specific pathways mediate cell migration. III. Examine the role of p75 receptor signal transduction in neurotrophin- mediated smooth muscle cell migration. These studies involve critical interactions with Dr. Gross, and Drs. Hajjar, Pomerantz, and Lander.