title: Bone morphogenetic protein receptor-2 signaling promotes pulmonary arterial endothelial cell survival: implications for loss-of-function mutations in the pathogenesis of pulmonary hypertension.
abstract: Mutations in the bone morphogenetic protein (BMP) receptor-2 (BMPR2) have been found in patients with idiopathic pulmonary arterial hypertension (IPAH); however, the mechanistic link between loss of BMPR2 signaling and the development of pulmonary arterial hypertension is unclear. We hypothesized that, contrary to smooth muscle cells, this pathway promotes survival in pulmonary artery endothelial cells (ECs) and loss of BMPR2 signaling will predispose to EC apoptosis. ECs were treated with BMP-2 or BMP-7 (200 ng/mL) for 24 hours in regular or serum-free (SF) medium, with and without addition of tumor necrosis factor alpha, and apoptosis was assessed by flow cytometry (Annexin V), TUNEL, or caspase-3 activity. Treatment for 24 hours in SF medium increased apoptosis, and both BMP-2 and BMP-7 significantly reduced apoptosis in response to serum deprivation to levels not different from serum controls. Transfection with 5 microg of small interfering RNAs for BMPR2 produced specific gene silencing assessed by RT-PCR and Western blot analysis. BMPR2 gene silencing increased apoptosis almost 3-fold (P=0.0027), even in the presence of serum. Circulating endothelial progenitor cells (EPCs) isolated from normal subjects or patients with IPAH were differentiated in culture for 7 days and apoptosis was determined in the presence and absence of BMPs. BMP-2 reduced apoptosis induced by serum withdrawal in EPCs from normal subjects but not in EPCs isolated from patients with IPAH. These results support the hypothesis that loss-of-function mutations in BMPR2 could lead to increased pulmonary EC apoptosis, representing a possible initiating mechanism in the pathogenesis of pulmonary arterial hypertension.
authors.affiliation: Terrence Donnelly Heart Center, Division of Cardiology, St. Michael's Hospital, Toronto, Canada.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Teichert-Kuliszewska
authors.forename: Michael J B
authors.initials: MJ
authors.lastname: Kutryk
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuliszewski
authors.forename: Golnaz
authors.initials: G
authors.lastname: Karoubi
authors.forename: David W
authors.initials: DW
authors.lastname: Courtman
authors.forename: Liana
authors.initials: L
authors.lastname: Zucco
authors.forename: John
authors.initials: J
authors.lastname: Granton
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Stewart
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis; D055396:Bone Morphogenetic Protein 2; D052006:Bone Morphogenetic Protein Receptors, Type II / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002470:Cell Survival; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000473:pathology*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011651:Pulmonary Artery / Q000473:pathology*; D015398:Signal Transduction / Q000502:physiology*; D013234:Stem Cells / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016212:Transforming Growth Factor beta; D052006:Bone Morphogenetic Protein Receptors, Type II