Prostacyclin and PPARα agonists control vascular smooth muscle cell apoptosis and phenotypic switch through distinct 14-3-3 isoforms

• Published in: PloS one 2013-07, Vol.8 (7), p.e69702
• Main Authors: Chen, Yen-Chung, Chu, Ling-Yun, Yang, Shu-Fan, Chen, Hua-Ling, Yet, Shaw-Fang, Wu, Kenneth K
• Format: Article
• Language: English
• Subjects: 14-3-3 protein; 14-3-3 Proteins - metabolism; Animals; Aorta; Apoptosis; Apoptosis - drug effects; Atherosclerosis; bcl-Associated Death Protein - metabolism; Biotechnology; Blood platelets; Calponin; Caspase; Caspase-3; Cell adhesion & migration; Circulatory system; Degradation; Epidermal growth factor; Epoprostenol - pharmacology; Fibroblasts; Growth factors; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; Inhibitors; Isoforms; Kinases; Laboratories; Medical research; Medicine; Muscle contraction; Muscle, Smooth, Vascular - metabolism; Muscles; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Phenotype; Plasmids; Polyclonal antibodies; PPAR alpha - agonists; Prostacyclin; Protein Binding; Protein Isoforms; Proteins; Proteolysis - drug effects; Pyrimidines - pharmacology; Rats; Serum response factor; siRNA; Smooth muscle; Transcription factors; Transfection
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0069702

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.