Modulation of type II TGF-β receptor degradation by integrin-linked kinase

J Invest Dermatol. 2015 Mar;135(3):885-894. doi: 10.1038/jid.2014.427. Epub 2014 Sep 30.

Abstract

Cutaneous responses to injury, infection, and tumor formation involve the activation of resident dermal fibroblasts and subsequent transition to myofibroblasts. The key for induction of myofibroblast differentiation is the activation of transforming growth factor-β (TGF-β) receptors and stimulation of integrins and their associated proteins, including integrin-linked kinase (ILK). Cross-talk processes between TGF-β and ILK are crucial for myofibroblast formation, as ILK-deficient dermal fibroblasts exhibit impaired responses to TGF-β receptor stimulation. We now show that ILK associates with type II TGF-β receptors (TβRII) in ligand- and receptor kinase activity-independent manners. In cells with targeted Ilk gene inactivation, cellular levels of TβRII are decreased, through mechanisms that involve enhanced ubiquitination and proteasomal degradation. Partitioning of TGF-β receptors into membrane has been linked to proteasome-dependent receptor degradation. We found that interfering with membrane raft formation in ILK-deficient cells restored TβRII levels and signaling. These observations support a model whereby ILK functions in fibroblasts to direct TβRII away from degradative pathways during their differentiation into myofibroblasts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation / physiology
  • Cells, Cultured
  • Fibroblasts / metabolism*
  • Fibroblasts / pathology
  • Mice
  • Mice, Mutant Strains
  • Models, Animal
  • Myofibroblasts / metabolism
  • Myofibroblasts / pathology
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Serine-Threonine Kinases / metabolism*
  • Receptor, Transforming Growth Factor-beta Type II
  • Receptors, Transforming Growth Factor beta / metabolism*
  • Signal Transduction / physiology
  • Skin / metabolism*
  • Skin / pathology

Substances

  • Receptors, Transforming Growth Factor beta
  • integrin-linked kinase
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type II
  • Proteasome Endopeptidase Complex