ACT,a pathophysiological inhibitor of MMP-9 activation

描述（由申请人提供）： 随着老龄化社会的日益加剧，伤口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功能和机制。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。ECM重塑的不充分或过度降解的中断与异常愈合如增生性瘢痕和慢性伤口有关。基质金属蛋白酶-9（MMP-9）通过切割前结构域而大量活化，已经在慢性伤口和其他退行性疾病如癌症转移中得到充分证实。我们以前的特点是proMMP-9激活剂作为一种组织结合胰凝乳蛋白酶样蛋白酶。最近的研究表明，在急性伤口液中存在抑制因子，其阻止proMMP-9转化为活性82-kDa酶。同时，我们确定了α 1-抗胰凝乳蛋白酶（α-ACT），一种急性期因子，作为一种有效的抑制剂的proMMP-9激活。相反，在慢性伤口中，α-ACT被降解、无功能并且失去其对proMMP-9转化的抑制。除肝细胞外，我们还将皮肤角质形成细胞鉴定为以前未识别的α-ACT来源。在该提案中，我们将解决三个具体目标：1）证明α-ACT作为伤口愈合中的病理生理学抑制剂的作用; 2）定义α-ACT抑制proMMP-9活化的机制; 3）研究皮肤角质形成细胞和伤口组织中的马槟榔碱调节α-ACT表达的机制。了解该抑制剂的功能、结构和调控机制，可为今后开发异常创伤和肿瘤转移的治疗提供信息。

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.