Stratifin-induced matrix metalloproteinase-1 in fibroblast is mediated by c-fos and p38 mitogen-activated protein kinase activation

Previously, we have demonstrated that keratinocyte releasable stratifin, also known as 14-3-3 sigma protein, stimulates matrix metalloproteinase (MMP)-1 expression in dermal fibroblasts. In this study, we showed that stratifin induced fibroblast MMP-1 messenger ribonucleic acid ( mRNA) and protein levels through p38 mitogen-activated protein kinase ( MAPK). Our data indicated that treatment of dermal fibroblasts with stratifin resulted in rapid and transient upregulation of c-jun and c-fos mRNA levels. We also demonstrated that SB203580 (SB), a specific inhibitor of p38 MAPK activity, inhibited the activation of. broblast MMP-1 mRNA expression by stratifin. Subsequently, western blot analysis revealed phosphorylation of p38 at 90 min after stratifin stimulation and this was decreased to approximately 50% of the maximum value by 120 min. Stratifin was demonstrated to increase MMP-1 protein levels starting at 4 h and reaching its peak at 12-24 h. Furthermore, SB significantly blocked the stratifin induction of MMP-1 protein levels (***p < 0.005, n = 3). Microarray analysis of strati. n-treated fibroblasts shows an increase in Elk4/Sap1 mRNA expression and this finding was confirmed by northern blot analysis. Our results indicate that strati. n markedly increase Elk4/Sap1 mRNA expression in a time-dependent fashion. In conclusion, strati. n stimulates. broblast MMP-1 levels through the activation of c-fos and MAPK pathway.