title: MicroRNA-96 inhibits FoxO3a function in IPF fibroblasts on type I collagen matrix.
abstract: Idiopathic pulmonary fibrosis (IPF) is a lethal and progressive lung disease characterized by persistent (myo)fibroblasts and the relentless accumulation of collagen matrix. Unlike normal lung fibroblasts, IPF lung fibroblasts have suppressed forkhead box O3a (FoxO3a) activity, which allows them to expand in this diseased environment. microRNA-96 (miR-96) has recently been found to directly bind to the 3'-untranslated region of FoxO3a mRNA, which subsequently inhibits its function. We examined whether aberrantly low FoxO3a expression is in part due to increased miR-96 levels in IPF fibroblasts on polymerized collagen, thereby causing IPF fibroblasts to maintain their pathological properties. miR-96 expression was upregulated in IPF fibroblasts compared with control fibroblasts when cultured on collagen. In contrast, FoxO3a mRNA levels were reduced in most IPF fibroblasts. However, when miR-96 function was inhibited, FoxO3a mRNA and protein expression were increased, suppressing IPF fibroblast proliferation and promoting their cell death in a dose-dependent fashion. Likewise, FoxO3a and its target proteins p21, p27, and Bim expression was also increased in the presence of a miR-96 inhibitor in IPF fibroblasts. However, when control fibroblasts were treated with miR-96 mimic, FoxO3a, p27, p21, and Bim mRNA and protein levels were decreased. In situ hybridization analysis further revealed the presence of enhanced miR-96 expression in cells within the fibroblastic foci of IPF lung tissue. Our results suggest that when IPF fibroblasts interact with collagen-rich matrix, pathologically altered miR-96 expression inhibits FoxO3a function, causing IPF fibroblasts to maintain their pathological phenotype, which may contribute to the progression of IPF.
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota; nhoxx002@umn.edu.
authors.forename: Richard Seonghun
authors.initials: RS
authors.lastname: Nho
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota;
authors.forename: Jintaek
authors.initials: J
authors.lastname: Im
authors.affiliation: Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota; and.
authors.forename: Yen-Yi
authors.initials: YY
authors.lastname: Ho
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota; Lung Morphology Research Core Department, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Polla
authors.initials: P
authors.lastname: Hergert
mesh_terms: D015153:Blotting, Western; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017403:In Situ Hybridization; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D024042:Collagen Type I; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C541492:MIRN96 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger
keywords: FoxO3a; IPF; cell death; collagen matrix; miR-96; proliferation