Inducible expression of tissue inhibitor of metalloproteinases-resistant matrix metalloproteinase-9 on the cell surface of neutrophils.
Inducible expression of tissue inhibitor of metalloproteinases-resistant matrix metalloproteinase-9 on the cell surface of neutrophils.
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DOI：
10.1165/rcmb.2003-0034oc
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发表时间：
2003-03
影响因子：
6.4
通讯作者：
C. Owen;Zhuma Hu;B. Barrick;S. Shapiro
中科院分区：
文献类型：
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作者：
C. Owen;Zhuma Hu;B. Barrick;S. Shapiro
活化的多形核中性粒细胞（PMN）分泌的基质金属蛋白酶(MMP)-9可能通过降解细胞外基质蛋白介导肺损伤。然而，MMP-9在金属蛋白酶组织抑制剂（TIMPs）存在下保持活性的机制尚不清楚。我们发现MMP-9也在PMN的细胞表面表达，促炎介质诱导MMP-9的细胞表面表达增加高达10倍。受刺激的人PMN表达活性形式的细胞表面MMP，其切割MMP底物McaPLGLDpaAR。利用来自MMP-9基因缺陷小鼠（MMP-9-/-）的PMN进行的功能丧失研究表明，膜结合的MMP-9在受刺激的PMN介导的McaPLGLDpaAR（约50%）和明胶（约70%）的表面结合切割中发挥了重要作用。与可溶性MMP-9一样，膜结合的MMP-9也能裂解McaPLGLDpaAR （Kcat/KM = 82,000 M-1s-1）、明胶、IV型胶原蛋白、弹性蛋白和α -1蛋白酶抑制剂。然而，与可溶性MMP-9相比，膜结合的MMP-9基本上不受TIMPs的抑制。TIMP-1和TIMP-2抑制膜结合MMP-9的IC50分别是可溶性MMP-9的21倍和68倍。MMP-9与PMN质膜的结合使其能够逃避TIMPs的抑制，从而可能改变细胞周围的蛋白水解平衡，有利于细胞外基质的降解。PMN上膜结合的MMP-9可能在炎症性肺部疾病中起致病作用。
Matrix metalloproteinase (MMP)-9 secreted by activated polymorphonuclear neutrophils (PMN) may play roles in mediating lung injury by degrading extracellular matrix proteins. However, the mechanisms by which MMP-9 retains activity in the presence of tissue inhibitors of metalloproteinases (TIMPs) are not known. We show that MMP-9 is also expressed on the cell surface of PMN, and proinflammatory mediators induce up to 10-fold increases in cell surface expression of MMP-9. Stimulated human PMN express active forms of cell surface MMP, which cleave the MMP substrate, McaPLGLDpaAR. Loss-of-function studies employing PMN from mice genetically deficient in MMP-9 (MMP-9-/-) demonstrate that membrane-bound MMP-9 contributes substantially to MMP-mediated surface-bound cleavage of McaPLGLDpaAR (approximately 50%) and gelatin (approximately 70%) by stimulated PMN. Like soluble MMP-9, membrane-bound MMP-9 cleaves McaPLGLDpaAR (Kcat/KM = 82,000 M-1s-1), gelatin, type IV collagen, elastin, and alpha1-proteinase inhibitor. However, in contrast to soluble MMP-9, membrane-bound MMP-9 is substantially resistant to inhibition by TIMPs. The IC50 for inhibition of membrane-bound MMP-9 by TIMP-1 and TIMP-2 are approximately 21-fold and approximately 68-fold higher, respectively, than those for inhibition of soluble MMP-9. The binding of MMP-9 to the plasma membrane of PMN enables it to evade inhibition by TIMPs, and thereby may alter the pericellular proteolytic balance in favor of extracellular matrix degradation. Membrane-bound MMP-9 on PMN may play pathogenetic roles in inflammatory lung diseases.