An antiproliferative BMP-2/PPARγ/apoE axis in human and murine SMCs and its role in pulmonary hypertension
Georg Hansmann, Vinicio A. de Jesus Perez, Tero-Pekka Alastalo, Cristina M. Alvira, Christophe Guignabert, Janine M. Bekker, Stefan Schellong, Takashi Urashima, Lingli Wang, Nicholas W. Morrell, Marlene Rabinovitch
Georg Hansmann, Vinicio A. de Jesus Perez, Tero-Pekka Alastalo, Cristina M. Alvira, Christophe Guignabert, Janine M. Bekker, Stefan Schellong, Takashi Urashima, Lingli Wang, Nicholas W. Morrell, Marlene Rabinovitch
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Research Article Cardiology

An antiproliferative BMP-2/PPARγ/apoE axis in human and murine SMCs and its role in pulmonary hypertension

Abstract

Loss-of-function mutations in bone morphogenetic protein receptor II (BMP-RII) are linked to pulmonary arterial hypertension (PAH); the ligand for BMP-RII, BMP-2, is a negative regulator of SMC growth. Here, we report an interplay between PPARγ and its transcriptional target apoE downstream of BMP-2 signaling. BMP-2/BMP-RII signaling prevented PDGF-BB–induced proliferation of human and murine pulmonary artery SMCs (PASMCs) by decreasing nuclear phospho-ERK and inducing DNA binding of PPARγ that is independent of Smad1/5/8 phosphorylation. Both BMP-2 and a PPARγ agonist stimulated production and secretion of apoE by SMCs. Using a variety of methods, including short hairpin RNAi in human PASMCs, PAH patient–derived BMP-RII mutant PASMCs, a PPARγ antagonist, and PASMCs isolated from PPARγ- and apoE-deficient mice, we demonstrated that the antiproliferative effect of BMP-2 was BMP-RII, PPARγ, and apoE dependent. Furthermore, we created mice with targeted deletion of PPARγ in SMCs and showed that they spontaneously developed PAH, as indicated by elevated RV systolic pressure, RV hypertrophy, and increased muscularization of the distal pulmonary arteries. Thus, PPARγ-mediated events could protect against PAH, and PPARγ agonists may reverse PAH in patients with or without BMP-RII dysfunction.

Authors

Georg Hansmann, Vinicio A. de Jesus Perez, Tero-Pekka Alastalo, Cristina M. Alvira, Christophe Guignabert, Janine M. Bekker, Stefan Schellong, Takashi Urashima, Lingli Wang, Nicholas W. Morrell, Marlene Rabinovitch

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Figure 6

Mice with targeted deletion of PPARγ in SMCs maintain BMP-2–induced pSmad1/5/8 signaling.

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Mice with targeted deletion of PPARγ in SMCs maintain BMP-2–induced pSma...
(A and B) Genotyping of mice with targeted deletion of PPARγ in SMCs. (A) PCR reactions showing gain of a 300-bp knockout transcript and almost complete loss of the 700-bp wild-type transcript in PASMCs and aorta from SM22α Cre PPARγflox/flox mice. In the lung, which contains SMCs but also many other cell types, both transcripts are found in SM22α Cre PPARγflox/flox mice, whereas only the wild-type transcript is detected in littermate control mice. (B) Western immunoblotting of PASMC lysates isolated from both littermate and SM22α Cre PPARγflox/flox (SMC PPARγ–/–) mice (n = 2 each) showed no detectable PPARγ protein expression when compared with control cells. (C) Both littermate control and SMC PPARγ–/– PASMCs were stimulated with BMP-2 (10 ng/ml) for 5–60 minutes as described in the legend for Figure 1, and phospho-Smad 1/5/8 protein expression was detected by immunoblotting as described in Methods (densitometric values were corrected for equal loading using α-tubulin). Data for 1 of 2 representative experiments with similar results are shown.