Peptide-mediated disruption of calmodulin-cyclin E interactions inhibits proliferation of vascular smooth muscle cells and neointima formation.

Division of Cell and Molecular Biology, Toronto General Hospital Research Institute, 200 Elizabeth St, MaRS 3-909, Toronto, Ontario, Canada.
Cell cycle progression in vascular smooth muscle cells (VSMCs) is a therapeutic target for restenosis.Having discovered that calmodulin (CaM)-dependent cyclin E/CDK2 activity underlies Ca(2+)-sensitive G(1)-to-S phase transitions in VSMCs, we sought to explore the physiological importance of the CaM-cyclin E interaction.A peptide based on the CaM binding sequence (CBS) of cyclin E was designed to interfere with CaM-cyclin E binding. Compared with control peptides, CBS blocked activating Thr160 phosphorylation of CDK2, decreased basal cyclin E/CDK2 activity, and eliminated Ca(2+)-sensitive cyclin E/CDK2 activity in nuclear extracts from mouse VSMCs. Nucleofection with CBS, or treatment with CBS conjugated to the HIV-1 TAT protein transduction domain to improve bioavailability, inhibited G(1)-to-S cell cycle progression in a dose-dependent manner. These effects were not observed with control peptides. TAT-CBS inhibited (3)H-thymidine incorporation in primary human aortic SMCs (HA-SMCs) in vitro, manifested greater transduction into HA-SMCs compared with endothelial cells in vitro, and limited decreased SM22α expression, neointima formation, and medial thickening without affecting collagen deposition or reendothelialization in a mouse model of carotid artery injury in vivo. The antiproliferative effects of CBS remained evident in mouse embryonic fibroblasts derived from wild-type mice but not cyclin E1/E2 double knockout mice.A synthetic peptide designed to disrupt CaM-cyclin E binding inhibits Ca(2+)/CaM-dependent CDK2 activity, cell cycle progression, and proliferation in VSMCs and limits arterial remodeling following injury. Importantly, this effect appears to be cyclin E-dependent and may form the basis of a potentially novel therapeutic approach for restenosis.
Mesh Terms:
Animals, Aorta, Binding Sites, Blood Proteins, Calmodulin, Coronary Restenosis, Cyclin E, Cyclin-Dependent Kinase 2, Extracellular Matrix, Hydrophobic and Hydrophilic Interactions, Mice, Muscle, Smooth, Vascular, Neointima, Peptides, Phosphorylation, Protein Kinases, S Phase
Circ. Res. Apr. 29, 2011; 108(9);1053-62 [PUBMED:21372285]
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