Signal Transduction of Human Keratinocyte Migration

人角质细胞（HK）的运动在人皮肤伤口的再上皮化中起着重要的作用。细胞外基质（ECMs）和血清生长因子（GFs）是控制HK迁移的两个主要刺激物。ecm和GFs结合它们的同源受体并激活不同但重叠的信号网络。ecm和GFs在控制HK迁移中的具体功能尚不清楚，我们的初步研究表明，ecm而不是GFs启动迁移。然而，ecm诱导的迁移是部分和非定向的，而GFs的作用似乎是指导和优化迁移。我们的假设是HK在结缔组织上的迁移是由ecm发起的，ecm与GFs协同工作以优化流动性并提供方向性。在这里，我们建议研究ecm启动的随机运动和生长因子优化的定向运动的信号机制。这些研究的重点将放在不含GFs的胶原基质（随机迁移）和胶原基质加GFs（定向和最佳迁移）的信号转导上。具体来说，我们将：1)研究Rho家族gtpase在存在或不存在GFs的情况下通过胶原基质迁移HK中的作用。不同的Rho家族GTPase成员在肌动蛋白细胞骨架和细胞迁移的调控中具有不同的功能。它们在香港运动中的作用尚不清楚。将采用药理学和遗传学方法研究这些gtpase在HKs中的作用；2)研究p38-MAPK和PKC-delta如何调节随机和定向迁移。我们最近的研究结果表明，p38-MAPK和PKC-delta是胶原基质上HK运动所必需的。在这里，我们将进一步研究这两种途径在hk中整合素和生长因子受体信号传导中的具体功能；3)通过一种新的“tgf - β阻断”方法鉴定和表征香港迁移相关基因。我们将利用tgf -阻断HKs的增殖而不是迁移这一事实。来自tgf - β处理的1)非迁移hk， 2)随机迁移hk和3)定向迁移hk的crna将进行DNA微阵列分析。微阵列鉴定的基因将进一步受到“途径筛选”方法的影响，以缩小Rac1-p38-MAPK途径和PKC-delta途径诱导的基因。这些研究共同揭示了伤口再上皮化的分子机制。

Human keratinocyte (HK) motility plays an important role in the re-epithelialization of human skin wounds. Extracellular matrices (ECMs) and serum growth factors (GFs) are the two main stimuli that control HK migration. ECMs and GFs bind to their cognate receptors and activate distinct, yet overlapping, signaling networks. The SPECIFIC function of ECMs versus GFs in the control of HK migration remains unclear, Our preliminary studies indicate that ECMs, but not GFs, initiate migration. The ECM-induced migration, however, is partial and non-directional, while GFs' role appears to direct and optimize migration. Our hypothesis is that HK migration on connective tissue is initiated by ECMs, which work in concert with GFs to optimize the molility and provide directionality. Here, we propose to study the signaling mechanisms of ECM-initiated random motility and growth factor-optimized directional motility. The focus of these studies will be on the signal transduction by a collagen matrix without GFs (random migration) and by a collagen matrix plus GFs (directional and optimal migration). Specifically, we will: 1) study the role of the Rho family GTPases in HK migration by a collagen matrix in the presence or absence of GFs. Different Rho family GTPase members have distinct functions in the regulation of the actin cytoskeleton and cell migration. Their functions in HK motility are not clear. Both pharmacological and genetic approaches will be used to study these GTPases in HKs; 2) study how p38-MAPK and PKC-delta regulate random versus directional migration. Our recent findings show that p38-MAPK and PKC-delta are independently required for HK motility on a collagen matrix (in press). Here, we will further investigate the specific function of these two pathways in the integrin and the growth factor receptor signaling in HKs; 3) identify and characterize HK migration-linked genes by a novel "TGF-beta block" approach. We will take advantage of the fact that TGF-beta blocks proliferation but not migration in HKs. cRNAs from TGF-beta- treated 1) non-migrating HKs, 2) randomly migrating HKs, and 3) directionally migrating HKs will be subjected to DNA microarray analysis. The microarray-identified genes will be further subjected to a "pathway-screening" approach to narrow down the Rac1-p38-MAPK pathway- and the PKC-delta pathway-induced genes. These studies collectively will shed new light on the molecular mechanisms of wound re-epithelialization.