The Role for miR-146b-5p in the Attenuation of Dermal Fibrosis and Angiogenesis by Targeting PDGFRα in Skin Wounds.

As a candidate microRNA antifibrotic effector in skin wounds, miR-146b-5p was upregulated by basic FGF, and PDGFRα was identified as a direct target of miR-146b-5p in fibroblasts. The treatment of fibroblasts with a miR-146b-5p mimic markedly downregulated the expression of PDGFRα and collagen type I. miR-146b-5p mimic transfection in wounds markedly attenuated cutaneous fibrosis, whereas a miR-146b-5p inhibitor strongly promoted fibrosis, with increases in PDGFRα and collagen I levels. These results indicate the positive effects of miR-146b-5p for the suppression of fibrosis, possibly through the inhibition of PDGFRα. The miR-146b-5p inhibitor markedly increased CD34+ vessel numbers and CD34 expression in wounds. We found miR-146b-5p+ cells in close contact with S100+ adipocytes. Moreover, we discovered the specific colocalization of the exosome marker CD81 and miR-146b-5p in the adipose tissue cells of mimic-transfected wounds, with miR-146b-5p signals being detected in the FSP1+ fibroblastic cells of adipose tissues. Therefore, fibroblastic cells of adipose tissues, which may specifically pick up and contain miR-146b-5p by exosome after transfection, may play an important role in the suppression of fibrosis. In this process, the inhibition of PDGFRα in adipose tissue cells by miR-146b-5p may lead to the loss of their PDGFRα-induced profibrotic activities, thereby suppressing fibrosis.

Cell-permeable p38 MAP kinase promotes migration of adult neural stem/progenitor cells.

Endogenous neural stem/progenitor cells (NPCs) can migrate toward sites of injury, but the migration activity of NPCs is insufficient to regenerate damaged brain tissue. In this study, we showed that p38 MAP kinase (p38) is expressed in doublecortin-positive adult NPCs. Experiments using the p38 inhibitor SB203580 revealed that endogenous p38 participates in NPC migration. To enhance NPC migration, we generated a cell-permeable wild-type p38 protein (PTD-p38WT) in which the HIV protein transduction domain (PTD) was fused to the N-terminus of p38. Treatment with PTD-p38WT significantly promoted the random migration of adult NPCs without affecting cell survival or differentiation; this effect depended on the cell permeability and kinase activity of the fusion protein. These findings indicate that PTD-p38WT is a novel and useful tool for unraveling the roles of p38, and that this protein provides a reasonable approach for regenerating the injured brain by enhancing NPC migration.