Differential regulation of miR‐21‐5p delays wound healing of melanocyte‐deprived vitiligo skin by modulating the expression of tumor‐suppressors PDCD4 and Maspin
Hemang D. Brahmbhatt, Rohit Gupta, Aayush Gupta, Soumya Rastogi, Dharshini Subramani, Ahmed Mobeen, Vineeta Vijay Batra, Archana Singh
Abstract
Abstract The loss of melanocytes in vitiligo is associated with architectural, transcriptional, and cellular perturbations of keratinocytes and manifests as a reduced proliferation potential in vitro and delayed re‐epithelialization in vivo. To understand the molecular mechanisms underlying this delay, microRNA (miRNA) profiling was performed on split skin biopsies collected on Day 1 (basal level) and Day 14 (wound re‐epithelialization) from nonlesional (NL) and lesional (L) skin of five subjects with stable nonsegmental vitiligo and 129 miRNAs were found to be differentially regulated between the NL and L healed epidermis. miR‐21‐5p, expressed at comparable levels on NL and L Day 1 samples, demonstrated significant upregulation during re‐epithelialization. However, the extent of its upregulation was relatively lower in L (10 times compared to Day 1) as compared to NL skin (17 times compared to Day 1). The overexpression of miR‐21 in keratinocytes led to a significant increase in the expression of proliferation markers (Ki67 and MCM6 messenger RNA, Ki67 positivity), along with an increase in keratinocyte migration. Using a small interfering RNA mediated knockdown approach, we further demonstrated that miR‐21‐5p mediates its effects by suppressing the expression of programmed cell death 4 (PDCD4) and mammary serine protease inhibitor (Maspin), both tumor‐suppressor genes. Investigation of clinical samples corroborated the lower miR‐21 levels and a higher expression of PDCD4 and Maspin in L Day 14 compared to the NL Day 14 epidermis. In conclusion, this study revealed that a relatively lower upregulation of miR‐21‐5p in L skin leads to significantly higher levels of PDCD4 and Maspin, delaying wound re‐epithelialization by reducing the proliferation and migration of keratinocytes.