Altered growth responses of pulmonary artery smooth muscle cells from patients with primary pulmonary hypertension to transforming growth factor-beta(1) and bone morphogenetic proteins.
BACKGROUND
Mutations in the type II receptor for bone morphogenetic protein (BMPR-II), a receptor member of the transforming growth factor-beta (TGF-beta) superfamily, underlie many cases of familial and sporadic primary pulmonary hypertension (PPH). We postulated that pulmonary artery smooth muscle cells (PASMCs) from patients with PPH might demonstrate abnormal growth responses to TGF-beta superfamily members.


RESULTS
For studies of (3)H-thymidine incorporation or cell proliferation, PASMCs (passages 4 to 8) were derived from main pulmonary arteries. In control cells, 24-hour incubation with TGF-beta(1) (10 ng/mL) or bone morphogenetic protein (BMP)-2, -4, and -7 (100 ng/mL) inhibited basal and serum-stimulated (3)H-thymidine incorporation, and TGF-beta(1) and BMPs inhibited the proliferation of serum-stimulated PASMCs. In contrast, TGF-beta(1) stimulated (3)H-thymidine incorporation (200%; P<0.001) and cell proliferation in PASMCs from PPH but not from patients with secondary pulmonary hypertension. In addition, BMPs failed to suppress DNA synthesis and proliferation in PASMCs from PPH patients. Reverse transcription-polymerase chain reaction of PASMC mRNA detected transcripts for type I (TGF-betaRI, Alk-1, ActRI, and BMPRIB) and type II (TGF-betaRII, BMPR-II, ActRII, ActRIIB) receptors. Receptor binding and cross-linking studies with (125)I-TGF-beta(1) confirmed that the abnormal responses in PPH cells were not due to differences in TGF-beta receptor binding. Mutation analysis of PASMC DNA failed to detect mutations in TGF-betaRII and Alk-1 but confirmed the presence of a mutation in BMPR-II in 1 of 5 PPH isolates.


CONCLUSIONS
We conclude that PASMCs from patients with PPH exhibit abnormal growth responses to TGF-beta(1) and BMPs and that altered integration of TGF-beta superfamily growth signals may contribute to the pathogenesis of PPH.
Morrell
N W
NW
Department of Medicine, University of Cambridge, Addenbrooke's and Papworth Hospitals, Cambridge, United Kingdom. nwm23@cam.ac.uk
Yang
X
X
Upton
P D
PD
Jourdan
K B
KB
Morgan
N
N
Sheares
K K
KK
Trembath
R C
RC
D029404:Activin Receptors; D000328:Adult; D001667:Binding, Competitive / Q000187:drug effects; D052006:Bone Morphogenetic Protein Receptors, Type II; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D004252:DNA Mutational Analysis; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D006976:Hypertension, Pulmonary / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics; D011651:Pulmonary Artery; D012333:RNA, Messenger / Q000096:biosynthesis; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013936:Thymidine / Q000493:pharmacokinetics; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
D019485:Bone Morphogenetic Proteins; D003432:Cross-Linking Reagents; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D004247:DNA; D017346:Protein Serine-Threonine Kinases; D029404:Activin Receptors; C498218:BMPR2 protein, human; D052006:Bone Morphogenetic Protein Receptors, Type II; D000077294:Receptor, Transforming Growth Factor-beta Type II; D013936:Thymidine