Bone morphogenetic protein receptor type II C-terminus interacts with c-Src: implication for a role in pulmonary arterial hypertension

Am J Respir Cell Mol Biol. 2005 Nov;33(5):438-46. doi: 10.1165/rcmb.2005-0103OC. Epub 2005 Jul 7.


Mutations of bone morphogenetic protein receptor type II (BMPR-II) have been associated with familial and idiopathic pulmonary arterial hypertension (PAH). BMPR-II is a member of the transforming growth factor-beta receptor superfamily. It consists of extracellular, transmembrane, and kinase domains, and a unique C-terminus with mostly unknown function. However, a number of PAH-causing mutations are predicted to truncate the C-terminus, suggesting that this domain plays an important role in the homeostasis of pulmonary vessels. In this study, we sought to elucidate the functional role of this C-terminus by seeking its interacting partners. Using yeast two-hybrid screening, we identified c-Src tyrosine kinase as a binding partner of this C-terminus. In vitro co-immunoprecipitation confirmed their interaction. Mutations truncating the C-terminus disrupted their interaction, while missense mutation within kinase domain reduced their interaction. In addition, BMPR-II and c-Src tyrosine kinase colocalized within intracellular aggregates when overexpressed in HEK293 cells. Moreover, mutations truncating the C-terminus disrupted their colocalization, whereas missense mutation within kinase domain had no effect on their colocalization. Furthermore, BMP ligand stimulation decreased c-Src-activating phosphorylation at Tyrosine 418 in pulmonary smooth muscle cells in both time- and concentration-dependent manners. Mutations that truncated the C-terminus abolished this response. Taken together, these results suggest a model in which proliferative effect of c-Src by vasoactive molecules is balanced by opposing effect of BMP signaling in basal state, and the loss of this balance due to BMPR2 mutations leads to increased c-Src activity and subsequently cell growth.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bone Morphogenetic Protein Receptors, Type II / analysis
  • Bone Morphogenetic Protein Receptors, Type II / genetics*
  • Bone Morphogenetic Protein Receptors, Type II / metabolism*
  • Bone Morphogenetic Proteins / pharmacology
  • CSK Tyrosine-Protein Kinase
  • Cells, Cultured
  • Cytoplasm / chemistry
  • Humans
  • Hypertension, Pulmonary / enzymology*
  • Hypertension, Pulmonary / genetics*
  • Immunoprecipitation
  • Lung / cytology
  • Mutation
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / metabolism
  • Phosphorylation
  • Protein Structure, Tertiary
  • Protein-Tyrosine Kinases / analysis
  • Protein-Tyrosine Kinases / metabolism*
  • Two-Hybrid System Techniques
  • Tyrosine / metabolism
  • src-Family Kinases


  • Bone Morphogenetic Proteins
  • Tyrosine
  • Protein-Tyrosine Kinases
  • CSK Tyrosine-Protein Kinase
  • src-Family Kinases
  • CSK protein, human
  • Bone Morphogenetic Protein Receptors, Type II