microRNA-21 mediates the TGF-β1-induced migration of keratinocytes via targeting PTEN.

OBJECTIVE: The aim of this study was to investigate the molecular mechanism into the keratinocyte migration, which is promoted by Transforming growth factor-β1 (TGF-β1) during wound healing.

MATERIALS AND METHODS: In the present study, we investigated the regulation by TGF-β1 on phosphatase and tensin homolog (PTEN) expression, and microRNA-21 (miR-21) level with real-time quantitative PCR or/and Western blotting, and then examined the regulatory role of miR-21 on the PTEN expression and the mesenchymal transition, with real-time quantitative PCR, western blotting and luciferase reporter assay, and the migration of keratinocytic HaCaT cells with scratch assay.

RESULTS: It was demonstrated that miR-21 was upregulated by TGF-β1 treatment in HaCaT cells; and the upregulated miR-21 targeted the 3' UTR of PTEN gene and downregulated the PTEN expression, along with the Smad3/4 upregulation. Moreover, the miR-21 manipulation with miR-21 mimics or miR-21 inhibitor not only upregulated or downregulated the miR-21 level, but also associated with the mesenchymal transition and the migration of HaCaT cells via promoting or downregulating the FSP1 and Collagen I and the E-cadherin, and via upregulating or downregulating the migration of HaCaT cells.

CONCLUSIONS: Our results demonstrate that miR-21 mediates the TGF-β1-promoted mesenchymal transition and migration of keratinocytes during skin wound healing via targeting PTEN. This study implies that miR-21 might be an important target to promote the skin wound healing.