ABSTRACT: The molecular mechanisms of lung injury and fibrosis are incompletely understood. microRNAs (miRNAs) are crucial biological regulators by suppression of their target genes and are involved in a variety of pathophysiologic processes. To gain insight into miRNAs in the regulation of lung fibrosis, total RNA was isolated from lung samples harvested at different days after bleomycin treatment, and miRNA array was performed thereafter. miRNAs expressed in lungs with bleomycin treatment at different time points were compared to miRNAs expressed in lungs without bleomycin treatment, resulting in 161 miRNAs differentially expressed. Furthermore, miRNA expression patterns regulated in initial and late periods after bleomycin were identified. Target genes were predicted in silico for differentially expressed miRNAs, including miR-7f, miR-7g, miR-196b, miR-16, miR-195, miR-25, miR-144, miR-351, miR-34a, miR-499, miR-704, miR-717, miR-10a, miR-211, miR-34a, miR-367 and miR-21, and then cross-referenced to molecular pathways including apoptosis, Wnt, Toll-like receptor, and TGF-β signaling, which are involved in different pathological phenotypes such as apoptosis, inflammation, and fibrosis. Our study demonstrated relative abundance of miRNA levels in bleomycin-induced lung fibrosis. The miRNAs and their potential target genes identified herein contribute to the understanding of the complex transcriptional program of lung fibrosis.
