title: Hypoxia inducible factor-1-dependent up-regulation of BMP4 mediates hypoxia-induced increase of TRPC expression in PASMCs.
abstract: OBJECTIVE
  Previously we demonstrated that both hypoxia inducible factor-1 (HIF-1) and bone morphogenetic protein-4 (BMP4) up-regulate transient receptor potential canonical (TRPC) 1 and TRPC6, resulting in increased basal intracellular Ca(2+) concentration ([Ca(2+)]i) in pulmonary arterial smooth muscle cells (PASMCs), driving development of chronic hypoxia (CH)-induced pulmonary hypertension (CHPH). This study aims to determine whether HIF-1 regulates BMP4, and whether BMP4 mediates TRPC and basal [Ca(2+)]i increases in hypoxic PASMCs.
  
  
  RESULTS
  The level of BMP4 mature protein was increased for ∼183% in distal pulmonary arterial smooth muscle (PA) from CH (10% O2 for 21 days; CH) exposed rats, and 143% in PASMCs cultured under prolonged hypoxia (4% O2 for 60 h). In rat PASMCs, HIF-1α overexpression up-regulated, whereas HIF-1α knockdown under hypoxia decreased BMP4 expression; site-mutation identified two functional HIF-1-binding sites in Bmp4 gene promoter; noggin or BMP4 siRNA treatment blocked hypoxia-induced increases of TRPC1 and TRPC6 expression and basal [Ca(2+)]i. Likewise, in mice, exposure to CH increased BMP4 expression in distal PA for ∼80%, which was absent in HIF-1α heterozygous mutant mice. Comparing with wild-type littermates, BMP4 heterozygous mutant mice exposed to CH displayed lower BMP4 and TRPC levels in PA, decreased basal [Ca(2+)]i in PASMCs, and attenuated CHPH. In human PASMCs, HIF-1α knockdown attenuated hypoxia-induced BMP4 expression and knockdown of either HIF-1α or BMP4 abolished hypoxia-induced TRPC expression and basal [Ca(2+)]i.
  
  
  CONCLUSIONS
  BMP4 acts downstream of HIF-1 and mediates hypoxia-induced up-regulation of TRPC, leading to increased basal [Ca(2+)]i in PASMCs, promoting CHPH pathogenesis.
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China Division of Pulmonary & Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21224, USA wlu92@yahoo.com jwang31@jhmi.edu.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Fu
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China Division of Pulmonary & Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21224, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Jia
authors.affiliation: Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Duan
authors.affiliation: Geisinger Medical Center, Danville, PA 17822, USA.
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Jianxing
authors.initials: J
authors.lastname: He
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Pixin
authors.initials: P
authors.lastname: Ran
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China.
authors.forename: Nanshan
authors.initials: N
authors.lastname: Zhong
authors.affiliation: Institute for Cell Engineering, Johns Hopkins University, Baltimore, MD 21224, USA.
authors.forename: Gregg L
authors.initials: GL
authors.lastname: Semenza
authors.affiliation: State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical University, Guangzhou, 151 Yanjiang Road, Guangzhou, Guangdong 510120, China Division of Pulmonary & Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21224, USA wlu92@yahoo.com jwang31@jhmi.edu.
authors.forename: Wenju
authors.initials: W
authors.lastname: Lu
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D011651:Pulmonary Artery / Q000378:metabolism*; D051381:Rats; D051898:Smad1 Protein / Q000502:physiology; D050052:TRPC Cation Channels / Q000235:genetics*; D000074287:TRPC6 Cation Channel; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C525809:BMP4 protein, human; D055415:Bone Morphogenetic Protein 4; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051898:Smad1 Protein; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C096351:transient receptor potential cation channel, subfamily C, member 1; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium
keywords: BMP4; Basal [Ca2+]i; HIF-1; PASMCs; TRPC
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