title: miR-210 promotes IPF fibroblast proliferation in response to hypoxia.
abstract: Idiopathic pulmonary fibrosis (IPF) is characterized by the relentless spread of fibroblasts from scarred alveoli into adjacent alveolar units, resulting in progressive hypoxia and death by asphyxiation. Although hypoxia is a prominent clinical feature of IPF, the role of hypoxia as a driver of the progressive fibrotic nature of the disease has not been explored. Here, we demonstrate that hypoxia robustly stimulates the proliferation of IPF fibroblasts. We found that miR-210 expression markedly increases in IPF fibroblasts in response to hypoxia and that knockdown of miR-210 decreases hypoxia-induced IPF fibroblast proliferation. Silencing hypoxia-inducible factor (HIF)-2α inhibits the hypoxia-mediated increase in miR-210 expression and blocks IPF fibroblast proliferation, indicating that HIF-2α is upstream of miR-210. We demonstrate that the miR-210 downstream target MNT is repressed in hypoxic IPF fibroblasts and that knockdown of miR-210 increases MNT expression. Overexpression of MNT inhibits hypoxia-induced IPF fibroblast proliferation. Together, these data indicate that hypoxia potently stimulates miR-210 expression via HIF-2α, and high miR-210 expression drives fibroblast proliferation by repressing the c-myc inhibitor, MNT. In situ analysis of IPF lung tissue demonstrates miR-210 expression in a similar distribution with HIF-2α and the hypoxic marker carbonic anhydrase-IX in cells within the IPF fibrotic reticulum. Our results raise the possibility that a pathological feed-forward loop exists in the IPF lung, in which hypoxia promotes IPF fibroblast proliferation via stimulation of miR-210 expression, which in turn worsens hypoxia.
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Vidya
authors.initials: V
authors.lastname: Bodempudi
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Polla
authors.initials: P
authors.lastname: Hergert
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Karen
authors.initials: K
authors.lastname: Smith
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Hong
authors.initials: H
authors.lastname: Xia
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Herrera
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Mark
authors.initials: M
authors.lastname: Peterson
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Wajahat
authors.initials: W
authors.lastname: Khalil
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Judy
authors.initials: J
authors.lastname: Kahm
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Bitterman
authors.affiliation: Department of Medicine, University of Minnesota, Minneapolis, Minnesota henke002@umn.edu.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Henke
mesh_terms: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000096:biosynthesis; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology; D002460:Cell Line; D049109:Cell Proliferation; D018450:Disease Progression; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D054990:Idiopathic Pulmonary Fibrosis / Q000503:physiopathology*; D008168:Lung / Q000473:pathology; D035683:MicroRNAs / Q000096:biosynthesis / Q000502:physiology*; D012097:Repressor Proteins / Q000096:biosynthesis; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D035683:MicroRNAs; D012097:Repressor Proteins; D000099162:Endothelial PAS Domain-Containing Protein 1; C543800:MIRN210 microRNA, human; C106465:MNT protein, human
keywords: fibroblast proliferation; hypoxia; idiopathic pulmonary fibrosis; miR-210