title: Peroxisome proliferator activated receptor-γ-Rho-kinase interactions contribute to vascular remodeling after chronic intrauterine pulmonary hypertension.
abstract: Peroxisome proliferator-activated receptor-γ (PPARγ) and Rho-kinase (ROCK) regulate smooth muscle cell (SMC) proliferation and contribute to vascular remodeling in adult pulmonary hypertension. Whether these pathways interact to contribute to the development of vascular remodeling in persistent pulmonary hypertension of the newborn (PPHN) remains unknown. We hypothesized that ROCK-PPARγ interactions increase SMC proliferation resulting in vascular remodeling in experimental PPHN. Pulmonary artery SMCs (PASMCs) were harvested from fetal sheep after partial ligation of the ductus arteriosus in utero (PPHN) and controls. Cell counts were performed daily for 5 days with or without PPARγ agonists and ROCK inhibition. PPARγ and ROCK protein expression/activity were measured by Western blot in normal and PPHN PASMCs. We assessed PPARγ-ROCK interactions by studying the effect of ROCK activation on PPARγ activity and PPARγ inhibition (siRNA) on ROCK activity and PASMC proliferation. At baseline, PPHN PASMC cell number was increased by 38% above controls on day 5. ROCK protein expression/activity were increased by 25 and 34% and PPARγ protein/activity decreased by 40 and 50% in PPHN PASMC. ROCK inhibition and PPARγ activation restored PPHN PASMC growth to normal values. ROCK inhibition increased PPARγ activity by 50% in PPHN PASMC, restoring PPARγ activity to normal. In normal PASMCs, ROCK activation decreased PPARγ activity and PPARγ inhibition increased ROCK activity and cell proliferation, resulting in a PPHN hyperproliferative PASMC phenotype. PPARγ-ROCK interactions regulate SMC proliferation and contribute to increased PPHN PASMC proliferation and vascular remodeling in PPHN. Restoring normal PPARγ-ROCK signaling may prevent vascular remodeling and improve outcomes in PPHN.
authors.affiliation: Perinatal Research Facility, 13243 E. 23rd Ave., Mail Stop F441, Aurora, CO 80045. jason.gien@ucdenver.edu.
authors.forename: Jason
authors.initials: J
authors.lastname: Gien
authors.forename: Nancy
authors.initials: N
authors.lastname: Tseng
authors.forename: Gregory
authors.initials: G
authors.lastname: Seedorf
authors.forename: Gates
authors.initials: G
authors.lastname: Roe
authors.forename: Steven H
authors.initials: SH
authors.lastname: Abman
mesh_terms: D000818:Animals; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D010547:Persistent Fetal Circulation Syndrome / Q000378:metabolism*; D012756:Sheep; D015398:Signal Transduction; D054460:rho-Associated Kinases / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D047495:PPAR gamma; D054460:rho-Associated Kinases
keywords: Rho-kinase (ROCK); peroxisome proliferator-activated gamma (PPARγ); persistent pulmonary hypertension of the newborn (PPHN); pulmonary artery smooth muscle cells (PASMC); vascular remodeling