title: Prostacyclin and PPARα agonists control vascular smooth muscle cell apoptosis and phenotypic switch through distinct 14-3-3 isoforms.
abstract: We hypothesized that prostacyclin (PGI2) protects vascular smooth muscle cell (VSMC) against apoptosis and phenotypic switch through peroxisome proliferator-activated receptor-α (PPARα) activation and 14-3-3 upregulation. Here we showed that transfection of rat aortic VSMC, A-10, with PGI2-producing vectors, Ad-COPI, resulted in attenuated H2O2-induced apoptosis accompanied by a selective increase in 14-3-3β and 14-3-3θ expression. Carbaprostacyclin (cPGI2) and Wy14,643 exerted a similar effect. The effects of PGI2 were abrogated by MK886, a PPARα antagonist, but not GSK3787, a PPARδ antagonist. PPARα transfection upregulated 14-3-3β and θ expression and attenuated H2O2-induced apoptosis. H2O2-induced 14-3-3β but not 14-3-3θ degradation was blocked by a caspase 3 inhibitor. Furthermore, 14-3-3β but not 14-3-3θ overexpression reduced, while 14-3-3β siRNA aggravated apoptosis. VSMC contractile proteins and serum response factor (SRF) were reduced in H2O2-treated A-10 cells which were concurrently prevented by caspase 3 inhibitor. By contrast, PGI2 prevented H2O2-induced SM22α and Calponin-1 degradation without influencing SRF. cPGI2 and Wy14,643 also effectively blocked VSMC phenotypic switch induced by growth factors (GFs). GFs suppressed 14-3-3β, θ, ε and η isoforms and cPGI2 prevented the decline of β, θ and η, but not ε. 14-3-3θ siRNA abrogated the protective effect of cPGI2 on SM22α and Calponin-1 while 14-3-3 θ or 14-3-3β overexpression partially restored SM22α. These results indicated that PGI2 protects VSMCs via PPARα by upregulating 14-3-3β and 14-3-3θ. 14-3-3β upregulation confers resistance to apoptosis whereas 14-3-3θ and β upregulation protects SM22α and Calponin-1 from degradation.
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan, Miaoli, Taiwan.
authors.forename: Yen-Chung
authors.initials: YC
authors.lastname: Chen
authors.forename: Ling-Yun
authors.initials: LY
authors.lastname: Chu
authors.forename: Shu-Fan
authors.initials: SF
authors.lastname: Yang
authors.forename: Hua-Ling
authors.initials: HL
authors.lastname: Chen
authors.forename: Shaw-Fang
authors.initials: SF
authors.lastname: Yet
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Wu
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D011464:Epoprostenol / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism*; D047493:PPAR alpha / Q000819:agonists*; D010641:Phenotype; D011485:Protein Binding; D020033:Protein Isoforms; D059748:Proteolysis / Q000187:drug effects; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D051025:bcl-Associated Death Protein / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D047493:PPAR alpha; D020033:Protein Isoforms; D011743:Pyrimidines; D051025:bcl-Associated Death Protein; C006253:pirinixic acid; D006861:Hydrogen Peroxide; D011464:Epoprostenol
keywords: 14-3-3; apoptosis; peroxisome proliferator-activated receptor; phenotypic switch; prostacyclin; smooth muscle cell