ACT,a pathophysiological inhibitor of MMP-9 activation

描述(由申请人提供)： 随着老龄化社会的加剧，创面愈合异常是美国的一个主要健康问题。我们的长期目标是阐明基质金属蛋白酶在组织修复中的作用和机制。细胞外基质(ECM)的重塑在组织修复中是必不可少的，并由特定的蛋白酶和抑制剂进行。由于降解不足或过度而导致ECM重塑的中断与诸如增生性瘢痕和慢性伤口等异常愈合有关。基质金属蛋白酶-9(MMP9)通过裂解原结构域而大量激活，在慢性创面和其他退行性疾病如癌症转移中得到了很好的证明。我们先前将原基质金属蛋白酶-9激活物定性为一种组织结合的类糜蛋白酶。最近的研究表明，急性创面液中存在抑制因子(S)，可阻止原基质金属蛋白酶-9转化为活性的82 kDa酶。同时，我们发现α1-抗糜蛋白酶(α-ACT)，一种急性时相因子，是一种有效的基质金属蛋白酶原激活的抑制物。相反，在慢性创面中，α-ACT降解，不起作用，失去对原基质金属蛋白酶-9转化的抑制作用。除了肝细胞外，我们还发现皮肤角质形成细胞是以前未被认识到的α-ACT来源。在这项提案中，我们将针对三个具体目标：1)证明α-ACT作为一种病理生理抑制物在伤口愈合中的作用；2)确定α-ACT抑制基质金属蛋白酶原9激活的机制；3)研究细胞因子调节皮肤角质形成细胞和伤口组织表达α-ACT的机制。了解该抑制物的功能、结构和调控机制，可为今后在异常创面和肿瘤转移治疗中的应用提供信息。

DESCRIPTION (provided by applicant): Abnormal wound healing is a major health problem in United Sates with the increasing of aging society. Our long term goal is to elucidate the function and mechanism of matrix metalloproteinases in tissue repair. Remodeling of extracellular matrix (ECM) is essential in tissue repair and carried out by specific proteinases and inhibitors. Interruption of ECM remodeling by either insufficient or excessive degradation is linked to abnormal healing such as hypertrophic scar and chronic wounds. Massive activation of matrix metalloproteinase-9 (MMP-9), by cleavage of the pro-domain, has been well documented in chronic wound and other degenerative diseases such as cancer metastasis. We previously characterized the proMMP-9 activator as a tissue bound chymotrypsin-like proteinase. Recent study showed the presence of inhibitory factor(s) in acute wound fluid, which prevents conversion of proMMP-9 into the active 82-kDa enzyme. Simultaneously, we identified alpha 1-antichymotrypsin (alpha-ACT), an acute phase factor, as a potent inhibitor for proMMP-9 activation. Conversely, in chronic wounds alpha-ACT is degraded, non-functional and loses its inhibition of proMMP-9 conversion. In addition to liver hepatocytes we also identified skin keratinocytes as a previously unrecognized source of alpha-ACT. In this proposal we will address three specific aims: 1) to demonstrate the role of alpha-ACT as a pathophysiological inhibitor in wound healing; 2) to define the mechanism by which alpha-ACT inhibits proMMP-9 activation; 3) to investigate the mechanism of cytokine-regulated expression of alpha-ACT by skin keratinocytes and the wound tissue. Understanding the function, structure and regulation of the inhibitor can provide information for future application in developing of therapy for abnormal wounds and cancer metastasis.