The Hippo pathway mediates inhibition of vascular smooth muscle cell proliferation by cAMP

• Published in: Journal of molecular and cellular cardiology 2016-01, Vol.90, p.1-10
• Main Authors: Kimura, Tomomi E, Duggirala, Aparna, Smith, Madeleine C, White, Stephen, Sala-Newby, Graciela B, Newby, Andrew C, Bond, Mark
• Format: Article
• Language: English
• Subjects: 3′-5′-Cyclic adenosine monophosphate; Amides - pharmacology; Animals; Apoptosis Regulatory Proteins - genetics; Apoptosis Regulatory Proteins - metabolism; Bridged Bicyclo Compounds, Heterocyclic - pharmacology; Bucladesine - metabolism; Bucladesine - pharmacology; cAMP; Cardiovascular; Cell Proliferation - drug effects; Colforsin - pharmacology; Connective Tissue Growth Factor - genetics; Connective Tissue Growth Factor - metabolism; Cyclic AMP - metabolism; Cysteine-Rich Protein 61 - genetics; Cysteine-Rich Protein 61 - metabolism; Epoprostenol - analogs & derivatives; Epoprostenol - pharmacology; Gene Expression Regulation; Humans; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Male; Muscle, Smooth - cytology; Muscle, Smooth - drug effects; Muscle, Smooth - metabolism; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Original; Primary Cell Culture; Proto-Oncogene Proteins c-myc - genetics; Proto-Oncogene Proteins c-myc - metabolism; Pyridines - pharmacology; Rats; Rats, Sprague-Dawley; rho-Associated Kinases - antagonists & inhibitors; rho-Associated Kinases - genetics; rho-Associated Kinases - metabolism; Signal Transduction; TAZ; TEAD; Thiazolidines - pharmacology; Transforming Growth Factor beta2 - genetics; Transforming Growth Factor beta2 - metabolism; VSMC; YAP
• ISSN: 0022-2828; 1095-8584
• DOI: 10.1016/j.yjmcc.2015.11.024

Abstract Aims Inhibition of vascular smooth muscle cell (VSMC) proliferation by intracellular cAMP prevents excessive neointima formation and hence angioplasty restenosis and vein-graft failure. These protective effects are mediated via actin-cytoskeleton remodelling and subsequent regulation of gene expression by mechanisms that are incompletely understood. Here we investigated the role of components of the growth-regulatory Hippo pathway, specifically the transcription factor TEAD and its co-factors YAP and TAZ in VSMC. Methods and results Elevation of cAMP using forskolin, dibutyryl-cAMP or the physiological agonists, Cicaprost or adenosine, significantly increased phosphorylation and nuclear export YAP and TAZ and inhibited TEAD-luciferase report gene activity. Similar effects were obtained by inhibiting RhoA activity with C3-transferase, its downstream kinase, ROCK, with Y27632, or actin-polymerisation with Latrunculin-B. Conversely, expression of constitutively-active RhoA reversed the inhibitory effects of forskolin on TEAD-luciferase. Forskolin significantly inhibited the mRNA expression of the pro-mitogenic genes, CCN1 , CTGF , c-MYC and TGFB2 and this was reversed by expression of constitutively-active YAP or TAZ phospho-mutants. Inhibition of YAP and TAZ function with RNAi or Verteporfin significantly reduced VSMC proliferation. Furthermore, the anti-mitogenic effects of forskolin were reversed by overexpression of constitutively-active YAP or TAZ. Conclusion Taken together, these data demonstrate that cAMP-induced actin-cytoskeleton remodelling inhibits YAP/TAZ–TEAD dependent expression of pro-mitogenic genes in VSMC. This mechanism contributes novel insight into the anti-mitogenic effects of cAMP in VSMC and suggests a new target for intervention.