MATRIX REGULATION OF CELL FUNCTION DURING WOUND HEALING

伤口瘢痕和挛缩是一个重要的临床问题，对手术患者具有潜在的严重后果，包括正常组织再生和邻近组织功能的损害。 瘢痕形成是成人伤口愈合过程的标志，是细胞因子、生长因子、蛋白酶、细胞外基质分子和成纤维细胞之间复杂且精细调节的相互作用的结果。 我们的长期目标是了解成纤维细胞活化的调控机制，并开发新的治疗方法来控制纤维增生。 纤连蛋白（FN）是细胞外基质蛋白，其在体外介导重要功能，例如细胞活化、增殖和迁移。FN水平的急剧增加发生在伤口部位，首先通过血浆FN从血液中外渗，然后通过伤口细胞合成。 选择性剪接片段（称为ED-A或EIIIA）包括在FN变体中，所述FN变体在愈合伤口中以特征性的空间和时间模式显著合成。 虽然在正常愈合伤口中短暂存在，但EIIIA+ FN在纤维增生期间持续存在。 当在体外测试时，EIIIA+ FN与TGF-β一起激活成纤维细胞以表达增加水平的SMC α-肌动蛋白。 本提案的假设指出，FN的EIIIA区段促进成纤维细胞的TGF-β依赖性活化，从而调节纤维增生。 提出了两个具体的目的来检验这一假设：（1）证明体内纤维增生的抑制作用;（2）确定EIIIA+ FN和TGF-β激活成纤维细胞的机制。 从拟议的工作中获得的发现将支持我们的总体目标，即开发新的治疗策略，以控制受伤组织瘢痕和收缩的程度。

Wound scarring and contracture is an important clinical problem with potentially serious consequences for the surgical patient, including impairment of normal tissue regeneration and neighboring tissue function. The scarring that is a hallmark of the wound healing process in adults occurs as a consequence of complex and finely regulated interactions between cytokines, growth factors, proteases, extracellular matrix molecules and fibroblasts. Our long term goal is to understand the regulatory mechanisms governing fibroblast activation and to develop new therapies to control fibroplasia. The fibronectins (FNs), are extracellular matrix proteins that mediate important functions, in vitro, such as cell activation, proliferation and migration. A dramatic increase in the levels of FNs occurs at wound sites, first by extravasation of plasma FN from blood, and then from synthesis by wound cells. An alternatively spliced segment (termed ED-A or EIIIA) is included in a FN variant synthesized prominently in healing wounds in a characteristic spatial and temporal pattern. Although present transiently in normal healing wounds, EIIIA+FNs persist during fibroplasia. When tested in vitro, EIIIA+FNs, together with TGF-beta, activate fibroblasts to express increased levels of SMC alpha-actin. The hypothesis of the present proposal states that the EIIIA segment of FN promotes the TGF-beta-dependent activation of fibroblasts and thereby regulates fibroplasia. Two specific aims are proposed to test this hypothesis: (1) Demonstrate inhibition of fibroplasia, in vivo; (2) Determine the mechanisms by which EIIIA+FNs and TGF- beta activate fibroblasts. Findings obtained from the proposed work will support our overall objective to develop new therapeutic strategies that will control the extent to which injured tissues scar and contract.