Downregulation of CFIm25 amplifies dermal fibrosis through Alternative Polyadenylation

Systemic sclerosis (SSc - scleroderma) is a multi-system, fibrotic disease affecting skin and internal organs. Alternative polyadenylation (APA) involves the differential usage of polyadenylation signals, which gives rise to transcripts with variable 3'UTR length. The mammalian Cleavage factor I 25kDa subunit (CFIm25, encoded by NUDT21) is a key regulator of alternative polyadenylation APA and its depletion causes predominantly 3'UTR shortening through loss of stimulation of distal polyA sites resulting in increased used of proximal polyA sites. A shortened 3'UTR will often lack microRNA target sites, resulting in increased mRNA translation due to evasion of microRNA-mediated gene repression. Herein, we report that CFlm25 is downregulated in SSc skin, and primary dermal fibroblasts, andas well as in two murine models of dermal fibrosis.The purpose of this experiment is to identify the APA targets of CFIm25 in human skin fibroblasts. Following the knockdown of CFIm25 in normal human skin fibroblasts, we identified 971 genes with shortened 3’UTRs, including those involved in the transforming growth factor-beta signaling pathway. mRNA profiles of primary human skin fibroblasts transfected with control or CFIm25 siRNA were generated by RNA-Seq using Illumina GAIIx