Study of laminin-5 in keratinocyte migration

层粘连蛋白a3链的LG4模块（a3 LG4）是上皮特异性层粘连蛋白5的一个组成部分，具有细胞附着活性并结合syndecan。在这里，我们发现重组a3 LG4和a3 LG4中具有syndecan结合活性的19-mer合成肽（A3G756）增加了角质形成细胞和成纤维细胞中基质金属蛋白酶-1 （MMP-1）的表达。这种诱导被肝素抑制，需要从头合成蛋白质。在角质形成细胞中，A3G756上调IL-1b和MMP-1的表达，IL-1受体拮抗剂完全抑制A3G756介导的MMP-1诱导。A3G756还能激活p38丝裂原活化蛋白激酶（p38MAPK）和细胞外信号相关激酶（Erk）。对MAPKs特异性抑制剂的研究表明，p38MAPK的激活对于IL-1b和MMP-1的诱导都是必需的，但Erk的激活仅对于MMP-1的诱导是必需的。在成纤维细胞中，IL-1受体拮抗剂不能阻断a3g756介导的MMP-1诱导。这些结果表明，a3 LG4诱导MMP-1在角质形成细胞中是通过IL-1b自分泌环介导的，但在成纤维细胞中的诱导机制不同。我们的研究表明，层粘连蛋白a3 LG4模块可能在伤口愈合过程中通过诱导MMP-1表达在组织重塑中发挥重要作用。

The LG4 module of the laminin a3 chain (a3 LG4), a component of epithelial-specific laminin-5, has cell attachment activity and binds syndecan. Here, we show that recombinant a3 LG4 and a 19-mer synthetic peptide (A3G756) within a3 LG4 active for syndecan binding increased the expression of matrix metalloproteinase-1 (MMP-1) in keratinocytes and fibroblasts. This induction was inhibited by heparin and required de novo synthesis of proteins. In keratinocytes, A3G756 upregulated IL-1b and MMP-1 expression and an IL-1 receptor antagonist thoroughly inhibited A3G756-mediated induction of MMP-1. A3G756 also activated p38 mitogen-activated protein kinase (p38MAPK) and extracellular signal-related kinase (Erk). Studies with specific inhibitors of MAPKs showed that p38MAPK activation was necessary for both IL-1b and MMP-1 induction, but Erk activation was required only for MMP-1 induction. In fibroblasts, IL-1 receptor antagonist did not block A3G756-mediated induction of MMP-1. These results indicated that induction of MMP-1 by a3 LG4 is mediated through the IL-1b autocrine loop in keratinocytes but the mechanism of the induction in fibroblasts is different. Our study suggests that the laminin a3 LG4 module may play an important role in tissue remodeling by inducing MMP-1 expression during wound healing.