The hedgehog system machinery controls transforming growth factor-β-dependent myofibroblastic differentiation in humans: involvement in idiopathic pulmonary fibrosis

Am J Pathol. 2012 Dec;181(6):2126-37. doi: 10.1016/j.ajpath.2012.08.019. Epub 2012 Sep 29.


Idiopathic pulmonary fibrosis (IPF) is a devastating disease of unknown cause. Key signaling developmental pathways are aberrantly expressed in IPF. The hedgehog pathway plays a key role during fetal lung development and may be involved in lung fibrogenesis. We determined the expression pattern of several Sonic hedgehog (SHH) pathway members in normal and IPF human lung biopsies and primary fibroblasts. The effect of hedgehog pathway inhibition was assayed by lung fibroblast proliferation and differentiation with and without transforming growth factor (TGF)-β1. We showed that the hedgehog pathway was reactivated in the IPF lung. Importantly, we deciphered the cross talk between the hedgehog and TGF-β pathway in human lung fibroblasts. TGF-β1 modulated the expression of key components of the hedgehog pathway independent of Smoothened, the obligatory signal transducer of the pathway. Smoothened was required for TGF-β1-induced myofibroblastic differentiation of control fibroblasts, but differentiation of IPF fibroblasts was partially resistant to Smoothened inhibition. Furthermore, functional hedgehog pathway machinery from the primary cilium, as well as GLI-dependent transcription in the nucleus, was required for the TGF-β1 effects on normal and IPF fibroblasts during myofibroblastic differentiation. These data identify the GLI transcription factors as potential therapeutic targets in lung fibrosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Cell Differentiation* / drug effects
  • Cell Differentiation* / genetics
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism
  • Cell Proliferation / drug effects
  • Cilia / drug effects
  • Cilia / pathology
  • Female
  • Gene Expression Regulation / drug effects
  • Hedgehog Proteins / genetics
  • Hedgehog Proteins / metabolism*
  • Humans
  • Idiopathic Pulmonary Fibrosis / genetics
  • Idiopathic Pulmonary Fibrosis / metabolism*
  • Idiopathic Pulmonary Fibrosis / pathology*
  • Immunohistochemistry
  • Lung / drug effects
  • Lung / metabolism
  • Lung / pathology
  • Male
  • Middle Aged
  • Models, Biological
  • Myofibroblasts / drug effects
  • Myofibroblasts / metabolism*
  • Myofibroblasts / pathology*
  • Phenotype
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Transforming Growth Factor beta / metabolism*
  • Veratrum Alkaloids / pharmacology


  • Hedgehog Proteins
  • RNA, Messenger
  • Transforming Growth Factor beta
  • Veratrum Alkaloids
  • cyclopamine