title: BMPR-II deficiency elicits pro-proliferative and anti-apoptotic responses through the activation of TGFβ-TAK1-MAPK pathways in PAH.
abstract: Pulmonary arterial hypertension (PAH) is a cardiovascular disorder associated with enhanced proliferation and suppressed apoptosis of pulmonary arterial smooth muscle cells (PASMCs). Heterozygous mutations in the type II receptor for bone morphogenetic protein (BMPR2) underlie the majority of the inherited and familial forms of PAH. The transforming growth factor β (TGFβ) pathway is activated in both human and experimental models of PAH. However, how these factors exert pro-proliferative and anti-apoptotic responses in PAH remains unclear. Using mouse primary PASMCs derived from knock-in mice, we demonstrated that BMPR-II dysfunction promotes the activation of small mothers against decapentaplegia-independent mitogen-activated protein kinase (MAPK) pathways via TGFβ-associated kinase 1 (TAK1), resulting in a pro-proliferative and anti-apoptotic response. Inhibition of the TAK1-MAPK axis rescues abnormal proliferation and apoptosis in these cells. In both hypoxia and monocrotaline-induced PAH rat models, which display reduced levels of bmpr2 transcripts, this study further indicates that the TGFβ-MAPK axis is activated in lungs following elevation of both expression and phosphorylation of the TAK1 protein. In ex vivo cell-based assays, TAK1 inhibits BMP-responsive reporter activity and interacts with BMPR-II receptor. In the presence of pathogenic BMPR2 mutations observed in PAH patients, this interaction is greatly reduced. Taken together, these data suggest dysfunctional BMPR-II responsiveness intensifies TGFβ-TAK1-MAPK signalling and thus alters the ratio of apoptosis to proliferation. This axis may be a potential therapeutic target in PAH.
authors.affiliation: Department of Medical and Molecular Genetics, King’s College London, London, UK. talat.nasim@kcl.ac.uk
authors.forename: Md Talat
authors.initials: MT
authors.lastname: Nasim
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ogo
authors.forename: Hasnin M
authors.initials: HM
authors.lastname: Chowdhury
authors.forename: Lan
authors.initials: L
authors.lastname: Zhao
authors.forename: Chien-nien
authors.initials: CN
authors.lastname: Chen
authors.forename: Christopher
authors.initials: C
authors.lastname: Rhodes
authors.forename: Richard C
authors.initials: RC
authors.lastname: Trembath
mesh_terms: D000818:Animals; D017209:Apoptosis; D052006:Bone Morphogenetic Protein Receptors, Type II / Q000378:metabolism*; D049109:Cell Proliferation; D002478:Cells, Cultured; D065627:Familial Primary Pulmonary Hypertension; D006976:Hypertension, Pulmonary / Q000378:metabolism* / Q000473:pathology; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D051379:Mice; D011651:Pulmonary Artery / Q000378:metabolism / Q000473:pathology; D051381:Rats; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D052006:Bone Morphogenetic Protein Receptors, Type II; D020930:MAP Kinase Kinase Kinases; D016212:Transforming Growth Factor beta; D000099151:MAP Kinase Kinase Kinase 7