Forkhead Box F1 represses cell growth and inhibits COL1 and ARPC2 expression in lung fibroblasts in vitro

Am J Physiol Lung Cell Mol Physiol. 2014 Dec 1;307(11):L838-47. doi: 10.1152/ajplung.00012.2014. Epub 2014 Sep 26.


Aberrant expression of master phenotype regulators or alterations in their downstream pathways in lung fibroblasts may play a central role in idiopathic pulmonary fibrosis (IPF). Interrogating IPF fibroblast transcriptome datasets, we identified Forkhead Box F1 (FOXF1), a DNA-binding protein required for lung development, as a candidate actor in IPF. Thus we determined FOXF1 expression levels in fibroblasts cultured from normal or IPF lungs in vitro, and explored FOXF1 functions in these cells using transient and stable loss-of-function and gain-of-function models. FOXF1 mRNA and protein were expressed at higher levels in IPF fibroblasts compared with normal fibroblasts (mRNA: +44%, protein: +77%). Immunohistochemistry showed FOXF1 expression in nuclei of bronchial smooth muscle cells, endothelial cells, and lung fibroblasts including fibroblastic foci of IPF lungs. In normal lung fibroblasts, FOXF1 repressed cell growth and expression of collagen-1 (COL1) and actin-related protein 2/3 complex, subunit 2 (ARPC2). ARPC2 knockdown inhibited cell growth and COL1 expression, consistent with FOXF1 acting in part through ARPC2 repression. In IPF fibroblasts, COL1 and ARPC2 repression by FOXF1 was blunted, and FOXF1 did not repress growth. FOXF1 expression was induced by the antifibrotic mediator prostaglandin E2 and repressed by the profibrotic cytokine transforming growth factor-β1 in both normal and IPF lung fibroblasts. Ex vivo, FOXF1 knockdown conferred CCL-210 lung fibroblasts the ability to implant in uninjured mouse lungs. In conclusion, FOXF1 functions and regulation were consistent with participation in antifibrotic pathways. Alterations of pathways downstream of FOXF1 may participate to fibrogenesis in IPF fibroblasts.

Keywords: FOXF1; actin-related protein 2–3 complex; cell differentiation; fibroblasts; fibrosis; forkhead transcription factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin-Related Protein 2-3 Complex / biosynthesis*
  • Actin-Related Protein 2-3 Complex / genetics
  • Animals
  • Apoptosis
  • Cell Nucleus / metabolism
  • Cell Proliferation
  • Cells, Cultured
  • Collagen Type I / biosynthesis*
  • Dinoprostone / pharmacology
  • Female
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Fibroblasts / transplantation
  • Forkhead Transcription Factors / biosynthesis
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / metabolism*
  • Gene Expression Profiling
  • Humans
  • Idiopathic Pulmonary Fibrosis / pathology*
  • Lung / cytology
  • Lung / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Middle Aged
  • RNA Interference
  • RNA, Messenger / biosynthesis
  • RNA, Small Interfering
  • Transforming Growth Factor beta1 / metabolism
  • Transforming Growth Factor beta1 / pharmacology


  • ARPC2 protein, human
  • Actin-Related Protein 2-3 Complex
  • Collagen Type I
  • FOXF1 protein, human
  • Forkhead Transcription Factors
  • RNA, Messenger
  • RNA, Small Interfering
  • Transforming Growth Factor beta1
  • Dinoprostone