LRP1 promotes synthetic phenotype of pulmonary artery smooth muscle cells in pulmonary hypertension.

Pulmonary hypertension (PH) is characterized by a thickening of the distal pulmonary arteries caused by medial hypertrophy, intimal proliferation and vascular fibrosis. Low density lipoprotein receptor-related protein 1 (LRP1) maintains vascular homeostasis by mediating endocytosis of numerous ligands and by initiating and regulating signaling pathways. Here, we demonstrate the increased levels of LRP1 protein in the lungs of idiopathic pulmonary arterial hypertension (IPAH) patients, hypoxia-exposed mice, and monocrotaline-treated rats. Platelet-derived growth factor (PDGF)-BB upregulated LRP1 expression in pulmonary artery smooth muscle cells (PASMC). This effect was reversed by the PDGF-BB neutralizing antibody or the PDGF receptor antagonist. Depletion of LRP1 decreased proliferation of donor and IPAH PASMC in a β1-integrin-dependent manner. Furthermore, LRP1 silencing attenuated the expression of fibronectin and collagen I and increased the levels of α-smooth muscle actin and myocardin in donor, but not in IPAH, PASMC. In addition, smooth muscle cell (SMC)-specific LRP1 knockout augmented α-SMA expression in pulmonary vessels and reduced SMC proliferation in 3D ex vivo murine lung tissue cultures. In conclusion, our results indicate that LRP1 promotes the dedifferentiation of PASMC from a contractile to a synthetic phenotype thus suggesting its contribution to vascular remodeling in PH.

Zucker MM ，Wujak L ，Gungl A ，Didiasova M ，Kosanovic D ，Petrovic A ，Klepetko W ，Schermuly RT ，Kwapiszewska G ，Schaefer L ，Wygrecka M ... -  《-》

PAR-2 inhibition reverses experimental pulmonary hypertension.

Kwapiszewska G ，Markart P ，Dahal BK ，Kojonazarov B ，Marsh LM ，Schermuly RT ，Taube C ，Meinhardt A ，Ghofrani HA ，Steinhoff M ，Seeger W ，Preissner KT ，Olschewski A ，Weissmann N ，Wygrecka M ... -  《-》

Mechanism of anti-remodelling action of treprostinil in human pulmonary arterial smooth muscle cells.

Lambers C ，Kornauth C ，Oberndorfer F ，Boehm PM ，Tamm M ，Klepetko W ，Roth M ... -  《PLoS One》

LRP1 Deficiency in Vascular SMC Leads to Pulmonary Arterial Hypertension That Is Reversed by PPARγ Activation.

Calvier L ，Boucher P ，Herz J ，Hansmann G ... -  《-》

Smooth muscle cell-specific FoxM1 controls hypoxia-induced pulmonary hypertension.

Forkhead box M1 (FoxM1) is a transcription factor that promotes cell proliferation by regulating a broad spectrum of genes that participate in cell cycle regulation, such as Cyclin B, CDC25B, and Aurora B Kinase. We have shown that hypoxia, a well-known stimulus for pulmonary hypertension (PH), induces FoxM1 in pulmonary artery smooth muscle cells (PASMC) in a HIF-dependent pathway, resulting in PASMC proliferation, while the suppression of FoxM1 prevents hypoxia-induced PASMC proliferation. However, the implications of FoxM1 in the development of PH remain less known. We determined FoxM1 levels in the lung samples of idiopathic PAH (pulmonary arterial hypertension) (IPAH) patients and hypoxia-induced PH mice. We generated constitutive and inducible smooth muscle cell (SMC)-specific FoxM1 knockdown or knockout mice as well as FoxM1 transgenic mice which overexpress FoxM1, and exposed them to hypoxia (10% O2, 90% N2) or normoxia (Room air, 21% oxygen) for four weeks, and measured PH indices. We also isolated mouse PASMC (mPASMC) and mouse embryonic fibroblasts (MEF) from these mice to examine the cell proliferation and expression levels of SMC contractile proteins. We showed that in hypertensive human lungs or mouse lungs, FoxM1 levels were elevated. Constitutive knockout of FoxM1 in mouse SMC caused early lethality, whereas constitutive knockdown of FoxM1 in mouse SMC prevented hypoxia-induced PH and PASMC proliferation. Inducible knockout of FoxM1 in SMC reversed hypoxia-induced pulmonary artery wall remodeling in existing PH. Overexpression of FoxM1 enhanced hypoxia-induced pulmonary artery wall remodeling and right ventricular hypertrophy in mice. Alteration of FoxM1 status did not affect hypoxia-induced hypoxia-inducible factor (HIF) activity in mice. Knockout of FoxM1 decreased PASMC proliferation and induced expression of SMC contractile proteins and TGF-β/Smad3 signaling. Our studies provide clear evidence that altered FoxM1 expression in PASMC contributes to PH and uncover a correlation between Smad3-dependent signaling in FoxM1-mediated proliferation and de-differentiation of PASMC.

Dai J ，Zhou Q ，Tang H ，Chen T ，Li J ，Raychaudhuri P ，Yuan JX ，Zhou G ... -  《-》