IL-1β induces proMMP-9 expression via c-Src-dependent PDGFR/PI3K/Akt/p300 cascade in rat brain astrocytes

Abstract

In a previous study, interleukin-1β (IL-1β) has been shown to induce matrix metalloproteinases (MMPs) expression through mitogen-activated protein kinases and nuclear factor-κB pathways in rat brain astrocytes. Moreover, transactivation of growth factor receptors and phosphatidylinositol 3-kinase (PI3K)/Akt cascade has been mentioned in the expression of several inflammatory genes. Here, we first report that IL-1β-induced up-regulation of proMMP-9 was inhibited by genistein. IL-1β also stimulated phosphorylation of several protein tyrosine kinases such as c-Src and platelet-derived growth factor receptor (PDGFR), which was further confirmed by western blotting using an anti-phospho-c-Src or anti-phospho-PDGFR antibody, respectively. IL-1β-stimulated c-Src, PDGFR, and Akt phosphorylation and proMMP-9 expression were attenuated by the inhibitors of c-Src (PP1), PDGFR (AG1296), and PI3K (LY294002), respectively, or transfection with dominant negative plasmid of c-Src or short hairpin RNAs of PDGFR and Akt. Moreover, IL-1β-induced proMMP-9 expression was blocked by pre-treatment with curcumin (a p300 inhibitor). We further confirmed that IL-1β stimulated p300 recruitment to MMP-9 promoter, and then acetylated histone H4 by immunoprecipitation and chromatin immunoprecipitation-PCR assays. The recruitment and activation of p300 in MMP-9 promoter were inhibited by pre-treatment with PP1, AG1296, and LY294002, respectively. Moreover, IL-1β stimulated the c-Src-dependent transactivation of PDGFR/PI3K/Akt cascade is independent of nuclear factor-κB pathway. These results indicated that in rat brain astrocytes cells, PI3K/Akt activation was mediated through c-Src-dependent transactivation of PDGFR promoted transcriptional co-factor p300 recruitment and activation and eventually led to increased proMMP-9 expression by IL-1β. © 2008 The Authors.