MAPK phosphorylation of connexin 43 promotes binding of cyclin E and smooth muscle cell proliferation

Johnstone, S.R. et al. (2012) MAPK phosphorylation of connexin 43 promotes binding of cyclin E and smooth muscle cell proliferation. Circulation Research, 111(2), pp. 201-211. (doi: 10.1161/CIRCRESAHA.112.272302)

Abstract

<p>Rationale: Dedifferentiation of vascular smooth muscle cells (VSMC) leading to a proliferative cell phenotype significantly contributes to the development of atherosclerosis. Mitogen-activated protein kinase (MAPK) phosphorylation of proteins including connexin 43 (Cx43) has been associated with VSMC proliferation in atherosclerosis.</p> <p>Objective: To investigate whether MAPK phosphorylation of Cx43 is directly involved in VSMC proliferation.</p> <p>Methods and Results: We show in vivo that MAPK-phosphorylated Cx43 forms complexes with the cell cycle control proteins cyclin E and cyclin-dependent kinase 2 (CDK2) in carotids of apolipoprotein-E receptor null (ApoE−/−) mice and in C57Bl/6 mice treated with platelet-derived growth factor–BB (PDGF). We tested the involvement of Cx43 MAPK phosphorylation in vitro using constructs for full-length Cx43 (Cx43) or the Cx43 C-terminus (Cx43CT) and produced null phosphorylation Ser>Ala (Cx43MK4A/Cx43CTMK4A) and phospho-mimetic Ser>Asp (Cx43MK4D/Cx43CTMK4D) mutations. Coimmunoprecipitation studies in primary VSMC isolated from Cx43 wild-type (Cx43+/+) and Cx43 null (Cx43−/−) mice and analytic size exclusion studies of purified proteins identify that interactions between cyclin E and Cx43 requires Cx43 MAPK phosphorylation. We further demonstrate that Cx43 MAPK phosphorylation is required for PDGF-mediated VSMC proliferation. Finally, using a novel knock-in mouse containing Cx43-MK4A mutation, we show in vivo that interactions between Cx43 and cyclin E are lost and VSMC proliferation does not occur after treatment of carotids with PDGF and that neointima formation is significantly reduced in carotids after injury.</p> <p>Conclusions: We identify MAPK-phosphorylated Cx43 as a novel interacting partner of cyclin E in VSMC and show that this interaction is critical for VSMC proliferation. This novel interaction may be important in the development of atherosclerotic lesions.</p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Johnstone, Dr Scott
• Authors: Johnstone, S.R., Kroncke, B.M., Straub, A.C., Best, A.K., Dunn, C.A., Mitchell, L.A., Peskova, Y., Nakamoto, R.K., Koval, M., Lo, C.W., Lampe, P.D., Columbus, L., and Isakson, B.E.
• Subjects: Q Science > Q Science (General); Q Science > QH Natural history > QH301 Biology; Q Science > QH Natural history > QH345 Biochemistry
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Circulation Research
• Publisher: American Heart Association
• ISSN: 0009-7330
• ISSN (Online): 1524-4571
• Published Online: 31 May 2012