Identification of collagen 1 as a post-transcriptional target of miR-29b in skin fibroblasts: therapeutic implication for scar reduction.

BACKGROUND: Excessive collagen synthesis and deposit during skin wound healing results in scar formation. MicroRNAs (miRNAs) are endogenous noncoding RNA regulators that mediate diverse biological functions through repressing target genes and hold great potentials for clinical therapeutic applications. The aim of the present study was to identify miRNAs as post-transcriptional regulators of collagen 1 in skin fibroblasts.
METHODS: miRNA candidates that potentially target collagen 1 were predicted by computational algorithms PicTar and TargetScan. The expression changes of collagen subunits 1α1 and 1α2 were measured by real-time reverse transcription-polymerase chain reaction and western blot after the primary skin fibroblasts were transfected with miR-29b mimics or inhibitor, respectively. A luciferase reporter assay was performed to further determine whether both collagen 1 subunits were probably direct targets of miR-29b.
RESULTS: Computational predictions identified several miRNAs as possible regulators for collagen 1 synthesis, including miR-29b. Enforced overexpression of miR-29b resulted in remarkable decrease of collagen 1α1 and 1α2, whereas knockdown of endogenous miR-29b induced pronounced increase of collagen 1α1 and 1α2 at both the messenger RNA and the protein levels. The luciferase activities were significantly inhibited when cells were cotransfected with reporter constructs and miR-29 mimics in vitro. Moreover, miR-29b transcriptional abundance inversely related to the levels of both collagen 1 subunits in skin scar as compared with normal skin.
CONCLUSIONS: Our data indicate that miR-29b is a potent post-transcriptional repressor of collagen 1 in skin fibroblasts and its deregulation might be implicated in scar formation, suggesting that miR-29b might represent a potential therapeutic target for scar reduction.