title: Peroxisome Proliferator-Activated Receptor γ-Mediated Inhibition on Hypoxia-Triggered Store-Operated Calcium Entry. A Caveolin-1-Dependent Mechanism.
abstract: Our previous publication demonstrated that peroxisome proliferator-activated receptor γ (PPARγ) inhibits the pathogenesis of chronic hypoxia (CH)-induced pulmonary hypertension by targeting store-operated calcium entry (SOCE) in rat distal pulmonary arterial smooth muscle cells (PASMCs). In this study, we aim to determine the role of a membrane scaffolding protein, caveolin-1, during the suppressive process of PPARγ on SOCE. Adult (6-8 weeks) male Wistar rats (200-250 g) were exposed to CH (10% O2) for 21 days to establish CH-induced pulmonary hypertension. Primary cultured rat distal PASMCs were applied for the molecular biological experiments. First, hypoxic exposure led to 2.5-fold and 1-fold increases of caveolin-1 protein expression in the distal pulmonary arteries and PASMCs, respectively. Second, effective knockdown of caveolin-1 significantly reduced hypoxia-induced SOCE for 58.2% and 41.5%, measured by Mn(2+) quenching and extracellular Ca(2+) restoration experiments, respectively. These results suggested that caveolin-1 acts as a crucial regulator of SOCE, and hypoxia-up-regulated caveolin-1 largely accounts for hypoxia-elevated SOCE in PASMCs. Then, by using a high-potency PPARγ agonist, GW1929, we detected that PPARγ activation inhibited SOCE and caveolin-1 protein for 62.5% and 59.8% under hypoxia, respectively, suggesting that caveolin-1 also acts as a key target during the suppressive process of PPARγ on SOCE in PASMCs. Moreover, by using effective small interfering RNAs against PPARγ and caveolin-1, and PPARγ antagonist, T0070907, we observed that PPARγ plays an inhibitory role on caveolin-1 protein by promoting its lysosomal degradation, without affecting the messenger RNA level. PPARγ inhibits SOCE, at least partially, by suppressing cellular caveolin-1 protein in PASMCs.
authors.affiliation: 1 State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.|2 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.affiliation: 1 State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.|2 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Wenju
authors.initials: W
authors.lastname: Lu
authors.affiliation: 1 State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.|2 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Qian
authors.initials: Q
authors.lastname: Jiang
authors.affiliation: 1 State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.|2 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Xin
authors.initials: X
authors.lastname: Yun
authors.affiliation: 3 Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, Maryland.
authors.forename: Mingming
authors.initials: M
authors.lastname: Zhao
authors.affiliation: 2 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Jiang
authors.affiliation: 1 State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.|4 Division of Pulmonary, the People's Hospital of Inner Mongolia, Hohhot, Inner Mongolia, China.|2 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D001577:Benzophenones / Q000494:pharmacology; D020013:Calcium Signaling; D051242:Caveolin 1 / Q000502:physiology*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D015870:Gene Expression; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000502:physiology; D047495:PPAR gamma / Q000819:agonists / Q000502:physiology*; D011485:Protein Binding; D059748:Proteolysis; D011651:Pulmonary Artery / Q000166:cytology; D017208:Rats, Wistar; D014443:Tyrosine / Q000031:analogs & derivatives / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D001577:Benzophenones; D051242:Caveolin 1; D047495:PPAR gamma; D014443:Tyrosine; C120099:GW 1929
keywords: caveolin-1; peroxisome proliferator–activated receptor γ; pulmonary arterial smooth muscle cells; pulmonary hypertension; store-operated calcium entry