title: Genotype-phenotype effects ofBmpr2mutations on disease severity in mouse models of pulmonary hypertension.
abstract: More than 350 mutations in the type-2 BMP (bone morphogenetic protein) receptor,BMPR2, have been identified in patients with heritable pulmonary arterial hypertension (HPAH). However, only 30% ofBMPR2mutation carriers develop PAH, and we cannot predict which of these carriers will develop clinical disease. One possibility is that the nature of theBMPR2mutation affects disease severity. This hypothesis has been difficult to test clinically, given the rarity of HPAH and the complexity of the confounding genetic and environmental risk factors. To test this hypothesis, therefore, we evaluated the susceptibility to experimental pulmonary hypertension (PH) of mice carrying different HPAH-associatedBmpr2mutations on otherwise identical genetic backgrounds. Mice withBmpr2ΔEx4-5 mutations (Bmpr2+/-), in which the mutant protein is not expressed, develop less severe PH in response to hypoxia or hypoxia with vascular endothelial growth factor receptor inhibition than mice with an extracellular-domainBmpr2ΔEx2 mutation (Bmpr2ΔEx2/+), in which the mutant protein is expressed. This was associated with a marked decrease in stabilizing phosphorylation of threonine 495 endothelial nitric oxide synthase (pThr495 eNOS) inBmpr2ΔEx2/+compared to wild-type andBmpr2+/-mouse lungs. These findings provide the first experimental evidence thatBMPR2mutation types influence the severity of HPAH and suggest that patients withBMPR2mutations who express mutant BMPR2 proteins by escaping non-sense-mediated messenger RNA decay (NMD- mutations) will develop more severe disease than HPAH patients with NMD+ mutations who do not express BMPR2 mutant proteins. Since decreased levels of pThr495 eNOS are associated with increased eNOS uncoupling, our data also suggest that this effect may result from defects in eNOS function.
authors.affiliation: Department of Cell and Developmental Biology, Vanderbilt University, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Frump
authors.affiliation: Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Arunima
authors.initials: A
authors.lastname: Datta
authors.affiliation: Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Sampa
authors.initials: S
authors.lastname: Ghose
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: James
authors.initials: J
authors.lastname: West
authors.affiliation: Department of Cell and Developmental Biology, Vanderbilt University, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Mark P
authors.initials: MP
authors.lastname: de Caestecker
keywords: bone morphogenetic protein type 2 receptor mutations; disease severity; endothelial nitric oxide synthase; experimental pulmonary hypertension; hereditary pulmonary arterial hypertension; non-sense-mediated messenger RNA decay