Phosphorylation of ezrin on Thr567 is required for the synergistic activation of cell spreading by EPAC1 and protein kinase A in HEK293T cells

Parnell, E., Koschinski, A., Zaccolo, M., Cameron, R. T., Baillie, G. S. , Baillie, G. L., Porter, A., McElroy, S. P. and Yarwood, S. J. (2015) Phosphorylation of ezrin on Thr567 is required for the synergistic activation of cell spreading by EPAC1 and protein kinase A in HEK293T cells. Biochimica et Biophysica Acta: Molecular Cell Research, 1853(7), pp. 1749-1758. (doi: 10.1016/j.bbamcr.2015.04.009) (PMID:25913012)

Abstract

Recent studies have demonstrated that the actin binding protein, ezrin, and the cAMP-sensor, EPAC1, cooperate to induce cell spreading in response to elevations in intracellular cAMP. To investigate the mechanisms underlying these effects we generated a model of EPAC1-dependent cell spreading based on the stable transfection of EPAC1 into HEK293T (HEK293T–EPAC1) cells. We found that direct activation of EPAC1 with the EPAC-selective analogue, 8-pCPT-2′-O-Me-cAMP (007), promoted cell spreading in these cells. In addition, co-activation of EPAC1 and PKA, with a combination of the adenylate cyclase activator, forskolin, and the cAMP phosphodiesterase inhibitor, rolipram, was found to synergistically enhance cell spreading, in association with cortical actin bundling and mobilisation of ezrin to the plasma membrane. PKA activation was also associated with phosphorylation of ezrin on Thr567, as detected by an electrophoretic band mobility shift during SDS-PAGE. Inhibition of PKA activity blocked ezrin phosphorylation and reduced the cell spreading response to cAMP elevation to levels induced by EPAC1-activation alone. Transfection of HEK293T–EPAC1 cells with inhibitory ezrin mutants lacking the key PKA phosphorylation site, ezrin-Thr567Ala, or the ability to associate with actin, ezrin-Arg579Ala, promoted cell arborisation and blocked the ability of EPAC1 and PKA to further promote cell spreading. The PKA phospho-mimetic mutants of ezrin, ezrin-Thr567Asp had no effect on EPAC1-driven cell spreading. Our results indicate that association of ezrin with the actin cytoskeleton and phosphorylation on Thr567 are required, but not sufficient, for PKA and EPAC1 to synergistically promote cell spreading following elevations in intracellular cAMP.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Baillie, Professor George and Zaccolo, Professor Manuela and Yarwood, Dr Stephen and Cameron, Mr Ryan and Koschinski, Dr Andreas and Parnell, Mr Euan
• Authors: Parnell, E., Koschinski, A., Zaccolo, M., Cameron, R. T., Baillie, G. S., Baillie, G. L., Porter, A., McElroy, S. P., and Yarwood, S. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health; College of Medical Veterinary and Life Sciences > School of Molecular Biosciences; College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Biochimica et Biophysica Acta: Molecular Cell Research
• ISSN: 0167-4889
• ISSN (Online): 1879-2596
• Copyright Holders: Copyright © 2015 The Authors
• First Published: First published in Biochimica et Biophysica Acta: Molecular Cell Research 1853(7):1749-1758
• Publisher Policy: Reproduced under a Creative Commons License