MicroRNAs in fibrosis: opportunities and challenges

MicroRNAs (miRNAs) are small, non-coding RNAs that mediate mRNA cleavage, translational repression or mRNA destabilisation and are around 22–25 nucleotides in length via partial complementary binding to the 3′ untranslated region in target transcripts. They are master regulators of gene expression. Fibrosis is an important cause of morbidity and mortality in the world, and there are currently no accepted treatments for fibrosis. Many novel miRNAs are now associated with fibrosis, both organ-specific and systemic, as in the prototypical fibrotic disease systemic sclerosis. Recently, the targets of these altered miRNAs have been validated and defined new biochemical pathways. Dysregulated miRNAs are amenable to therapeutic modulation. This review will examine the role of miRNAs in fibrosis and the opportunities and challenges of targeting them.