latrunculin-b and cicaprost

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.. 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.. 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.

Topics: Amides; Animals; Apoptosis Regulatory Proteins; Bridged Bicyclo Compounds, Heterocyclic; Bucladesine; Cell Proliferation; Colforsin; Connective Tissue Growth Factor; Cyclic AMP; Cysteine-Rich Protein 61; Epoprostenol; Gene Expression Regulation; Humans; Intracellular Signaling Peptides and Proteins; Male; Muscle, Smooth; Myocytes, Smooth Muscle; Primary Cell Culture; Proto-Oncogene Proteins c-myc; Pyridines; Rats; Rats, Sprague-Dawley; rho-Associated Kinases; Signal Transduction; Thiazolidines; Transcriptional Coactivator with PDZ-Binding Motif Proteins; Transforming Growth Factor beta2; YAP-Signaling Proteins