LOCALIZATION AND ACTIVATION OF METALLOPROTEINASES

来源于白细胞的基质金属蛋白酶（MMPs）对细胞外基质成分的损伤是致残性慢性疾病（如肺气肿、囊性纤维化、急性呼吸窘迫综合征和类风湿性关节炎）的关键发病事件。mmp介导的组织损伤的流行概念是，mmp作为前酶自由分泌到细胞外空间。然而，关于prommp在体内被激活的机制，或者它们如何在细胞外空间规避高亲和力抑制剂的作用的信息很少。我们的初步数据表明，MMP-7（基质溶解素）、MMP-8（中性粒细胞胶原酶）和MMP-9 （92 kDa明胶酶、92 kDa IV型胶原酶、明胶酶B）在人白细胞的细胞表面表达，并且它们的表达被促炎介质上调。我们建议测试假设，当MMPs被限制在白细胞的细胞表面时，它们被集中并保护免受自然发生的抑制剂的影响。为此，我们将努力实现以下具体目标：确定哪些MMPs （MMP-7、-8、-9和MMP- 12[巨噬细胞金属弹性酶]）在中性粒细胞和单核细胞的细胞表面表达，量化它们在细胞活化时的表达，并研究MMPs和粘附分子在活化细胞膜上的协调表达促进MMP介导的细胞外蛋白水解的可能性。2. 检查MMPs与炎症细胞表面结合的后果，包括前酶激活、催化活性和对抑制的敏感性。3. 探讨MMPs与白细胞膜结合的机制。我们预计，拟议的研究将为MMPs介导组织损伤的机制提供新的见解，并且这些知识将有助于合理开发有效的治疗策略，用于许多慢性和致残疾病，其中mmp介导的组织损伤是一个关键事件。

Injury to extracellular matrix components by matrix metalloproteinases (MMPs) derived from leukocytes is a pivotal pathogenetic event in disabling chronic diseases such as pulmonary emphysema, cystic fibrosis, acute respiratory distress syndrome, and rheumatoid arthritis. The prevailing concept of MMP-mediated tissue injury is that MMPs are freely secreted into the extracellular space as proenzymes. However, there is little information available about the mechanisms by which proMMPs are activated in vivo, or how they circumvent the effects of high- affinity inhibitors within the extracellular space. Our preliminary data indicate that MMP-7 (matrilysin), MMP-8 (neutrophil collagenase), and MMP-9 (92 kDa gelatinase; 92 kDa type IV collagenase; gelatinase B) are expressed on the cell surface of human leukocytes, and that their expression is upregulated by pro-inflammatory mediators. We propose to test the hypothesis that when MMPs are confined to the cell surface of leukocytes, they are focused and protected from naturally- occurring inhibitors. In doing so, we will pursue the following Specific Aims: 1. Determine which MMPs (MMP-7, -8, -9 and MMP- 12[macrophage metalloelastase]) are expressed on the cell surface of neutrophils and monocytes, quantify their expression in response to cellular activation, and investigate the possibility that coordinate expression of MMPs and adhesion molecules on activated cell membranes facilitates MMP-mediated extracellular proteolysis. 2. Examine the consequences of binding of MMPs to the cell surface of inflammatory cells with respect to proenzyme activation, catalytic activity and susceptibility to inhibition. 3. Investigate the mechanisms of binding of MMPs to leukocyte cell membranes. We anticipate that the proposed studies will provide novel insights into the mechanisms by which MMPs mediate tissue injury, and that this knowledge will facilitate rational development of effective therapeutic strategies for many chronic and disabling diseases in which MMP-mediated tissue injury is a critical event.