Bone morphogenetic protein receptor type II C-terminus interacts with c-Src: implication for a role in pulmonary arterial hypertension.
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.
Wong
Wai K P
WK
Department of Medicine, Columbia University College of Physicians and Surgeons, and the New York State Psychiatric Institute, New York, New York 10032, USA. wpw2001@columbia.edu
Knowles
James A
JA
Morse
Jane H
JH
D052006:Bone Morphogenetic Protein Receptors, Type II / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D000081247:CSK Tyrosine-Protein Kinase; D002478:Cells, Cultured; D003593:Cytoplasm / Q000737:chemistry; D006801:Humans; D006976:Hypertension, Pulmonary / Q000201:enzymology* / Q000235:genetics*; D047468:Immunoprecipitation; D008168:Lung / Q000166:cytology; D009154:Mutation; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases
D019485:Bone Morphogenetic Proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D052006:Bone Morphogenetic Protein Receptors, Type II