title: MicroRNA-21 plays a role in hypoxia-mediated pulmonary artery smooth muscle cell proliferation and migration.
abstract: Hypoxia stimulates pulmonary artery smooth muscle cell (PASMC) proliferation. Recent studies have implicated an important role for microRNAs (miRNAs) in hypoxia-mediated responses in various cellular processes, including cell proliferation. In this study, we investigated the role of microRNA-21 (miR-21) in hypoxia-induced PASMC proliferation and migration. We first demonstrated that miR-21 expression increased by ∼3-fold in human PASMC after 6 h of hypoxia (3% O₂) and remained high (∼2-fold) after 24 h of hypoxia. Knockdown of miR-21 with anti-miR-21 inhibitors significantly reduced hypoxia-induced cell proliferation, whereas miR-21 overexpression in normoxia enhanced cell proliferation. We also found that miR-21 is essential for hypoxia-induced cell migration. Protein expression of miR-21 target genes, specifically programmed cell death protein 4 (PDCD4), Sprouty 2 (SPRY2), and peroxisome proliferator-activated receptor-α (PPARα), was decreased in hypoxia and in PASMC overexpressing miR-21 in normoxia and increased in hypoxic cells in which miR-21 was knocked down. In addition, PPARα 3'-untranslated region (UTR) luciferase-based reporter gene assays demonstrated that PPARα is a direct target of miR-21. Taken together, our findings indicate that miR-21 plays a significant role in hypoxia-induced pulmonary vascular smooth muscle cell proliferation and migration by regulating multiple gene targets.
authors.affiliation: Dept. of Pediatrics, University of Illinois College of Medicine at Chicago, 60612, USA. jsarkar1@uic.edu
authors.forename: Joy
authors.initials: J
authors.lastname: Sarkar
authors.forename: Deming
authors.initials: D
authors.lastname: Gou
authors.forename: Prasanna
authors.initials: P
authors.lastname: Turaka
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Viktorova
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Ramchandran
authors.forename: J Usha
authors.initials: JU
authors.lastname: Raj
mesh_terms: D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology*; D011651:Pulmonary Artery / Q000166:cytology*
chemical_list: C524940:MIRN21 microRNA, human; D035683:MicroRNAs