miR-127-3p is an epigenetic activator of myofibroblast senescence situated within the miRNA enriched Dlk1-Dio3 imprinted domain on mouse chromosome 12 [miRNA array]. miR-127-3p is an epigenetic activator of myofibroblast senescence situated within the miRNA enriched Dlk1-Dio3 imprinted domain on mouse chromosome 12 [miRNA array]

During wound healing, fibroblasts differentiate into non-proliferative contractile myofibroblasts, contribute to skin repair, and eventually undergo apoptosis or become senescent. MicroRNAs (miR) are posttranscriptional regulators of gene expression networks that control cell fate and survival and may also regulate senescence. Here we determined regulated miRs in myofibroblasts isolated from wounds and analyzed their role in senescent myofibroblast formation. Transcriptome profiling showed that a 200 kbp region of the Dlk1-Dio3 imprinted domain on mouse chromosome 12 encodes for most of the upregulated miRs in the entire genome of mouse myofibroblasts. Among those, miR-127-3p induced a myofibroblast-like phenotype associated with a block in proliferation. Molecular analysis revealed that miR-127-3p induced a prolonged cell-cycle arrest with unique molecular features of senescence, including the activation of the senescence-associated ß-galactosidase, increase in p21 levels, inhibition of lamin B1, proliferation factors, and the production of senescence-associated inflammatory and extracellular matrix -remodeling components. Hence, miR-127-3p emerges as an epigenetic activator regulating the transition from repair to remodeling during skin wound healing, but may also induce age-related defects, pathological scarring and fibrosis, all linked to myofibroblast senescence. Overall design: Non-hematopoietic (CD45-)/non-endothelial (CD31-) cell populations with low expression of SMA-GFP from dermis (SMA-GFP+) and with high expression from wounds 7 days post injury (SMA-GFP+++) were isolated by cell sorting from transgenic SMA-GFP mice. Total RNA of was isolated with TRIZOL (Life Technologies) and RNA quality was confirmed using micro capillary electrophoresis (2100 Bioanalyzer, Agilent). ~50ng of RNA was amplified, labeled and hybridized to Sureprint G3 human GE 8x60K or whole genome mRNA microarray according to the manufacturer’s specifications (Low input Quick Amp Labeling kit, Agilent). The arrays were scanned (Agilent G2595C scanner), data extracted and processed to create a generic gene level experiments from two technologies using the Genespring 14.5 software (Agilent).