Mechanisms of tumor necrosis factor-a-induced expression of matrix metalloproteinase -9 (MMP-9) in human retinal pigment epithelial cells

• Main Authors: Ching Ting Wang, 王靜婷
• Other Authors: C. M. Yang
• Format: Others
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/98223782768721979486

碩士 === 長庚大學 === 生物醫學研究所 === 99 === Matrix metalloproteinase 9 (MMP-9) plays an important role in the pathogenesis of human choroidal neovascularization (CNV) occurring during the exudation most aggressive form of age-related-macular degeneration (AMD). Retinal pigment epithelial cells (RPECs) are an important source of MMPs in the outer retinal environment, which are modulated by various factors including tumor necrosis facror-a (TNF-a). TNF-a is a potent pro-inflammatory cytokine and significantly increases MMP-9 secretion in RPECs. However, the mechanisms underlying TNF-a-induced MMP-9 expression in human RPECs remain unclear. Gelatin zymography, Western blot, and real time-PCR analyses showed that TNF-a induced expression of MMP-9 mRNA and protein in a time-dependent manner in RPECs, which was attenuated by the inhibitors of MEK1/2 (U0126), p38 MAPK (SB202190) and JNK1/2 (SP600125). In accordance with these findings, TNF-a stimulated phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK1/2 which were attenuated by U0126, SB202190, and SP600125, respectively. Moreover, TNF-a-stimulated phosphorylation of Akt led to expression of MMP-9 in RPECs, which was inhibited by pretreatment with the inhibitors of c-Src (PP1), EGF receptor (AG1478), and PI3K (LY294002). TNF-a-stimulated translocation of NF-kB into the nucleus and degradation of IkB-a was revealed by Western blotting and immnofluorescence staining, which was blocked by Bay11-7082. TNF-a-induced MMP-9 expression also was attenuated by AP-1 inhibitors (Tanshinone IIA and Curcumin). These findings indicated that TNF- induced MMP-9 expression in cultured RPE cells, activation of p42/p44 MAPK, p38 MAPK, JNK1/2, EGFR, PI3K/Akt, NF-kB, and AP-1 pathway are essential for TNF-a-induced MMP-9 gene expression. More impact information of pathological processes of retinal events affected by TNF-a and MMP-9, will prove beneficial in the therapeutic intervention against inflammatory disease in eyes.