| Summary: | 碩士 === 長庚大學 === 生物醫學研究所 === 98 === There is increasing evidence that the dry eye induces inflammation on the ocular surface through increases of pro-inflammatory mediators and catalytic enzymes. Matrix metalloproteinases (MMPs) such as MMP-9 have been proposed to play a key role in the pathogenesis of inflammation and tissue wound healing in cornea. The activity of MMP-9 has been shown to be induced by several factors such as IL-1b, which could be responsible for collagen degradation and tissue remodeling in the inflammatory responses of cornea. However, the mechanisms underlying IL-1beta-induced MMP-9 expression in cornea remains unknown. Here we applied the Statens Seruminstitut rabbit corneal keratocyte (SIRC cells) to investigate the mechanisms of IL-1beta-induced MMP-9 expression. Data obtained with Western blotting and RT-PCR analyses showed that IL-1beta-induced MMP-9 protein and mRNA expression as well as phosphorylation of p42/p44 MAPK and JNK, were attenuated by pretreatment with the inhibitors of MEK1/2 (PD98059), and JNK1/2 (SP600125). Moreover, IL-1beta-induced MMP-9 expression was mediated through phosphorylation of Akt which was attenuated by pretreatment with the inhibitor of c-Src (PP1), EGFR (AG1478), PDGFR (AG1296), or PI3-K (LY294002). Furthermore, IL-1beta-induced MMP-9 expression was inhibited by a selective NF-kB inhibitor (Bay11-7082), consistent with that IL-1beta stimulated both IkBa degradation and NF-kB p65 translocation in these cells. In addition to NF-kB, AP-1 was also involved in IL-1bbeta-induced MMP-9 expression which was attenuated by pretreatment with an AP-1 inhibitor (Tanshione). Moreover, IL-1beta-induce activation of MMP-9 promoter activity was blocked by these selective inhibitors. These results suggested that in SIRCs, IL-1beta-induced MMP-9 expression was mediated through the activation of MAPKs, transativation of EGFR and PDGFR, AP-1, and NF-kB pathways. IL-1beta regulated NF-kB transloction into the nucleus and c-Jun/AP-1 activation via Erk1/2 and JNK1/2 phsphorylation. Moreover, IL-1b also regulated NF-kB activation via the c-Src/PDGFR, EGFR/PI3K/Akt pathway. Increased understanding of signal transduction mechanisms underlying MMP-9 expression induced by IL-1beta will create therapeutic strategies of corneal ulceration
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