miR-221 promotes keratinocyte proliferation and migration by targeting SOCS7 and is regulated by YB-1.

Proliferation and migration of keratinocytes are vital processes for the successful epithelization specifically after wounding. MiR-221 has been identified to play a potential role in promoting wound regeneration by inducing blood vessel formation. However, little is known about the role of miR-221 in the keratinocyte proliferation and migration during wound healing. An in vivo mice wound-healing model was generated; the expression levels of miR-221 were assessed by qRT-PCR and fluorescence in situ hybridization. Initially, we found that miR-221 was upregulated in the proliferative phase of wound healing. Further, in an in vivo wound-healing mice model, targeted delivery of miR-221 mimics accelerated wound healing. Contrastingly, inhibition of miR-221 delayed healing. Additionally, we observed that overexpression of miR-221 promoted cell proliferation and migration, while inhibition of miR-221 had the opposite effects. Moreover, we identified SOCS7 as a direct target of miR-221 in keratinocytes and overexpression of SOCS7 reversed the effects of miR-221 in HaCaT keratinocytes. Finally, we identified that YB-1 regulates the expression of miR-221 in HaCaT keratinocytes. Overall, our experiments suggest that miR-221 is regulated by YB-1 in HaCaT keratinocytes and acts on SOCS7, thereby playing an important role in HaCaT keratinocyte proliferation and migration during wound healing.