title: PPARγ Ligands Attenuate Hypoxia-Induced Proliferation in Human Pulmonary Artery Smooth Muscle Cells through Modulation of MicroRNA-21.
abstract: Pulmonary hypertension (PH) is a progressive and often fatal disorder whose pathogenesis involves pulmonary artery smooth muscle cell (PASMC) proliferation. Although modern PH therapies have significantly improved survival, continued progress rests on the discovery of novel therapies and molecular targets. MicroRNA (miR)-21 has emerged as an important non-coding RNA that contributes to PH pathogenesis by enhancing vascular cell proliferation, however little is known about available therapies that modulate its expression. We previously demonstrated that peroxisome proliferator-activated receptor gamma (PPARγ) agonists attenuated hypoxia-induced HPASMC proliferation, vascular remodeling and PH through pleiotropic actions on multiple targets, including transforming growth factor (TGF)-β1 and phosphatase and tensin homolog deleted on chromosome 10 (PTEN). PTEN is a validated target of miR-21. We therefore hypothesized that antiproliferative effects conferred by PPARγ activation are mediated through inhibition of hypoxia-induced miR-21 expression. Human PASMC monolayers were exposed to hypoxia then treated with the PPARγ agonist, rosiglitazone (RSG,10 μM), or in parallel, C57Bl/6J mice were exposed to hypoxia then treated with RSG. RSG attenuated hypoxic increases in miR-21 expression in vitro and in vivo and abrogated reductions in PTEN and PASMC proliferation. Antiproliferative effects of RSG were lost following siRNA-mediated PTEN depletion. Furthermore, miR-21 mimic decreased PTEN and stimulated PASMC proliferation, whereas miR-21 inhibition increased PTEN and attenuated hypoxia-induced HPASMC proliferation. Collectively, these results demonstrate that PPARγ ligands regulate proliferative responses to hypoxia by preventing hypoxic increases in miR-21 and reductions in PTEN. These findings further clarify molecular mechanisms that support targeting PPARγ to attenuate pathogenic derangements in PH.
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Atlanta Veterans Affairs Medical Center / Emory University, Atlanta, GA, United States of America.
authors.forename: David E
authors.initials: DE
authors.lastname: Green
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Atlanta Veterans Affairs Medical Center / Emory University, Atlanta, GA, United States of America.
authors.forename: Tamara C
authors.initials: TC
authors.lastname: Murphy
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Atlanta Veterans Affairs Medical Center / Emory University, Atlanta, GA, United States of America.
authors.forename: Bum-Yong
authors.initials: BY
authors.lastname: Kang
authors.affiliation: Department of Medicine, Division of Cardiology, Atlanta Veterans Affairs Medical Center / Emory University, Atlanta, GA, United States of America.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Searles
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Atlanta Veterans Affairs Medical Center / Emory University, Atlanta, GA, United States of America.
authors.forename: C Michael
authors.initials: CM
authors.lastname: Hart
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008024:Ligands; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism*; D047495:PPAR gamma / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology*; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D008024:Ligands; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D047495:PPAR gamma; D045162:Thiazolidinediones; D053773:Transforming Growth Factor beta1; D000077154:Rosiglitazone; D051059:PTEN Phosphohydrolase