The Regulation of MMP–2 and –14 Expressions by TGF–ß in Lens Epithelial Cells

Abstract

Abstract: : Purpose: TGF–ß is a key regulator of epithelial–mesenchymal transition (EMT) that induced actin rearrangement, ECM accumulation, migration, cell arrest, and apoptosis in epithelial cells. Among these TGF–ß responses, the cell migration is closely associated with the expression of matrix metalloproteinases (MMPs). Therefore, we determined which of MMPs is regulated by TGF–ß and examined the TGF–ß signaling involved in this event, focusing on Src family tyrosine kinases (SFKs) and epidermal growth factor receptor (EGFR), which were previously reported to be activated by TGF–ß. Methods: We firstly examined if the cell migration induced by TGF–ß is associated with SFKs, EGFR and MMPs using specific inhibitors, PP2, AG1478 and GM6001, respectively. The migration assay was performed by wound healing assay, as previously reported. And then, we screened the expression of MMPs in epithelial cells (HaCaT and HLE B3) treated with TGF–ß, using RT–PCR and Northern blot analysis. It was examined whether the expression of MMPs is regulated by SFKs and EGFR in epithelial cell lines. Furthermore, we confirmed this event in vivo using the model of lens epithelial explants cultured with TGF–ß by RT–PCR. Results: The cell migration induced by TGF–ß in epithelial cells was suppressed by PP2, AG1478, and GM6001. RT–PCR and Northern blotting analysis was revealed that the expressions of MMP–2, –3, –12, and –14 in HaCaT and that of MMP–2 in HLE B3 were up–regulated by TGF–ß. Of these MMPs, the expression of MMP–14 was blocked by PP2 and AG1478 in HaCaT, whereas these inhibitors had no effect on the expression of MMP–2 in HaCaT and HLE B3. The regulation of MMPs expression in vitro was confirmed in vivo model, in rat lens explant culture, that MMP–2 and –14 also were up–regulated and MMP–14 was regulated by SFKs and EGFR signaling. Conclusions: The cell migration induced by TGF–ß is closely related to the functions of MMPs and the expression of MMP–14 is specifically involved in SFKs and EGFR signaling. Herein, we suggest a novel role of SFKs and EGFR signaling in the expression of MMP–14 induced by TGF–ß.

Keywords: metabolism • extracellular matrix • cataract