Exposure of cryptic domains in the α1-chain of laminin-1 by elastase stimulates macrophages urokinase and matrix metalloproteinase-9 expression
Exposure of cryptic domains in the α1-chain of laminin-1 by elastase stimulates macrophages urokinase and matrix metalloproteinase-9 expression
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DOI：
10.1074/jbc.m111290200
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发表时间：
2002-04-19
影响因子：
4.8
通讯作者：
Falcone, DJ
中科院分区：
文献类型：
--
作者：
Khan, KMF;Laurie, GW;Falcone, DJ
细胞外基质的降解导致碎片的释放，从而引发与完整分子不同的生物反应。我们报道了α1:Ser(2091)-Arg(2108)，一种源自laminin-1 α1链的肽，触发蛋白激酶C依赖性MAPK(erk1/2)激活，导致巨噬细胞尿激酶型纤溶酶原激活剂和基质金属蛋白酶(MMP)-9表达上调。由于完整的 laminin-1 未能触发这些事件，我们假设 alpha1:Ser(2091)-Arg(2108) 是神秘的或假定巨噬细胞无法识别的构象。在这里，我们证明弹性蛋白酶裂解 laminin-1 会产生片段，这些片段刺激 RAW264.7 巨噬细胞和腹膜巨噬细胞表达蛋白酶。相反，MMP-2、MMP-7 或纤溶酶产生的片段对巨噬细胞蛋白酶的表达没有影响。弹性蛋白酶产生的 laminin-1 片段通过肝素-琼脂糖层析进行分级。肝素结合片段刺激巨噬细胞的蛋白酶表达比非结合片段高几倍。肝素结合片段与针对 α1 链区域（包括 α1:Ser(2091)-Arg(2108) 和球状结构域）的抗体反应。球状结构域第一个环的肽 (α1:Ser(2179)-Ser(2198)) 触发 MAPK(erk1/2) 磷酸化，并刺激巨噬细胞尿激酶型纤溶酶原激活剂和 MMP-9 的表达。此外，从主动脉瘤中分离出的肝素结合部分含有α1链片段，并刺激巨噬细胞的蛋白酶表达。基于这些数据，我们得出结论，层粘连蛋白 α1 链 COOH 末端部分的隐藏结构域通过蛋白水解而暴露，并刺激巨噬细胞的蛋白酶表达。
Degradation of the extracellular matrix leads to the release of fragments, which elicit biological responses distinct from intact molecules. We have reported that alpha1:Ser(2091)-Arg(2108), a peptide derived from the alpha1-chain of laminin-1, triggers protein kinase C-dependent activation of MAPK(erk1/2), leading to the up-regulation of macrophage urokinase type plasminogen activator and matrix metalloproteinase (MMP)-9 expression. Since intact laminin-1 failed to trigger these events, we hypothesized that alpha1:Ser(2091)-Arg(2108) is cryptic or assumes a conformation not recognized by macrophages. Here we demonstrate that elastase cleavage of laminin-1 generates fragments, which stimulate proteinase expression by RAW264.7 macrophages and peritoneal macrophages. In contrast, fragments generated by MMP-2, MMP-7, or plasmin had no effect on macrophage proteinase expression. Elastase-generated laminin-1 fragments were fractionated by heparin-Sepharose chromatography. Heparin-binding fragments stimulated macrophages' proteinase expression severalfold greater than nonbinding fragments. The heparin binding fragments reacted with antibodies directed against regions of the alpha1-chain including alpha1:Ser(2091)-Arg(2108) and the globular domain. A peptide from the first loop of the globular domain (alpha1:Ser(2179)-Ser(2198)) triggered the phosphorylation of MAPK(erk1/2) and stimulated the expression of macrophage urokinase type plasminogen activator and MMP-9. Moreover, a heparin-binding fraction isolated from an aortic aneurysm contained fragments of alpha1-chain and stimulated macrophages' proteinase expression. Based on these data, we conclude that cryptic domains in the COOH-terminal portion of the alpha1-chain of laminin are exposed by proteolysis and stimulate macrophages' proteinase expression.