Fibrillin degradation by matrix metalloproteinases: implications for connective tissue remodelling
Fibrillin degradation by matrix metalloproteinases: implications for connective tissue remodelling
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DOI：
10.1042/0264-6021:3400171
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发表时间：
1999-05-15
影响因子：
4.1
通讯作者：
Kielty, CM
中科院分区：
文献类型：
--
作者：
Ashworth, JL;Murphy, G;Kielty, CM
纤维蛋白是10- 12nm直径的细胞外基质弹性微原纤维的主要结构成分。我们以前已经表明，原纤维分子和组装的微原纤维都容易被丝氨酸蛋白酶降解。在这项研究中，我们研究了6种基质金属蛋白酶（MMP-2、MMP-3、MMP-9、MMP-12、MMP-13和MMP-14）对原纤维蛋白分子和从纤毛带分离的完整的富含原纤维蛋白的微纤维的潜在分解代谢作用，利用新合成的重组原纤维蛋白分子，鉴定了原纤维蛋白1的主要裂解位点。特别是，六种不同的MMPs从分子的n端区域产生了类似于45 kDa的主要降解产物，而截断的、未处理的和furin处理的c端也产生了大量降解产物。在钙结合的表皮生长因子样结构域中引入单个异位引起的氨基酸取代（E2447K；氨基酸的单字母符号），预计会破坏钙结合，显著改变c端纤维蛋白-1降解的模式。然而，在上游钙结合表皮生长因子样结构域具有类似E -> K取代的突变型fibrin -1的断裂模式与野生型分子难以区分。超微结构检查显示，从纤毛带分离的富含纤维蛋白的微原纤维被MMPs严重破坏。这是第一次证明原纤维蛋白分子和富含原纤维蛋白的微原纤维被MMPs降解，并且某些氨基酸取代改变了断裂模式。这些研究对生理和病理纤维蛋白分解代谢以及衰老和疾病中结缔组织弹性的丧失具有重要意义。
Fibrillin is the principal structural component of the 10-12 nm diameter elastic microfibrils of the extracellular matrix. We have previously shown that both fibrillin molecules and assembled microfibrils are susceptible to degradation by serine proteases. In this study, we have investigated the potential catabolic effects of six matrix metalloproteinases (MMP-2, MMP-3, MMP-9, MMP-12, MMP-13 and MMP-14) on fibrillin molecules and on intact fibrillin-rich microfibrils isolated from ciliary zonules, Using newly synthesized recombinant fibrillin molecules, major cleavage sites within fibrillin-1 were identified. In particular, the six different MMPs generated a major degradation product of similar to 45 kDa from the N-terminal region of the molecule, whereas treatment of truncated, unprocessed and furin-processed C-termini also generated large degradation products. Introduction of a single ectopia lentis-causing amino acid substitution (E2447K; one-letter symbols for amino acids) in a calcium- binding epidermal growth factor-like domain, predicted to disrupt calcium binding, markedly altered the pattern of C-terminal fibrillin-1 degradation. However, the fragmentation pattern of a mutant fibrillin-1 with a comparable E --> K substitution in an upstream calcium-binding epidermal growth factor-like domain was indistinguishable from wild-type molecules. Ultrastructural examination highlighted that fibrillin-rich microfibrils isolated from ciliary zonules were grossly disrupted by MMPs. This is the first demonstration that fibrillin molecules and fibrillin-rich microfibrils are degraded by MMPs and that certain amino acid substitutions change the fragmentation patterns. These studies have important implications for physiological and pathological fibrillin catabolism and for loss of connective tissue elasticity in ageing and disease.