Increase in Ca2+ current by sustained cAMP levels enhances proliferation rate in GH3 cells

Rodrigues, A. L., Brescia, M., Kolshinski, A., Moreira, T. H., Cameron, R. T., Baillie, G. , Beirão, P. S.L., Zaccollo, M. and Cruz, J. S. (2018) Increase in Ca2+ current by sustained cAMP levels enhances proliferation rate in GH3 cells. Life Sciences, 192, pp. 144-150. (doi: 10.1016/j.lfs.2017.11.040) (PMID:29183797)

Abstract

Aims: Ca2 + and cAMP are important intracellular modulators. In order to generate intracellular signals with various amplitudes, as well as different temporal and spatial properties, a tightly and precise control of these modulators in intracellular compartments is necessary. The aim of this study was to evaluate the effects of elevated and sustained cAMP levels on voltage-dependent Ca2 + currents and proliferation in pituitary tumor GH3 cells. Main methods: Effect of long-term exposure to forskolin and dibutyryl-cyclic AMP (dbcAMP) on Ca2 + current density and cell proliferation rate were determined by using the whole-cell patch-clamp technique and real time cell monitoring system. The cAMP levels were assayed, after exposing transfected GH3 cells with the EPAC-1 cAMP sensor to forskolin and dbcAMP, by FRET analysis. Key findings: Sustained forskolin treatment (24 and 48 h) induced a significant increase in total Ca2 + current density in GH3 cells. Accordingly, dibutyryl-cAMP incubation (dbcAMP) also elicited increase in Ca2 + current density. However, the maximum effect of dbcAMP occurred only after 72 h incubation, whereas forskolin showed maximal effect at 48 h. FRET-experiments confirmed that the time-course to elevate intracellular cAMP was distinct between forskolin and dbcAMP. Mibefradil inhibited the fast inactivating current component selectively, indicating the recruitment of T-type Ca2 + channels. A significant increase on cell proliferation rate, which could be related to the elevated and sustained intracellular levels of cAMP was observed. Significance: We conclude that maintaining high levels of intracellular cAMP will cause an increase in Ca2 + current density and this phenomenon impacts proliferation rate in GH3 cells.

• Item Type: Articles
• Additional Information: This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq – Grant #308007/2013-1), Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG)- Grants #10274/16 and #00056/15), and Fundação Mineira de Educação e Cultura (Universidade FUMEC).
• Keywords: Ca(2+) channels, cell proliferation, FRET-imaging, forskolin, patch-clamp, cAMP.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Baillie, Professor George and Cameron, Mr Ryan
• Authors: Rodrigues, A. L., Brescia, M., Kolshinski, A., Moreira, T. H., Cameron, R. T., Baillie, G., Beirão, P. S.L., Zaccollo, M., and Cruz, J. S.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Life Sciences
• Publisher: Elsevier
• ISSN: 0024-3205
• ISSN (Online): 1879-0631
• Published Online: 26 November 2017
• Copyright Holders: Copyright © 2017 Elsevier Inc.
• First Published: First published in Life Sciences 192: 144-150
• Publisher Policy: Reproduced in accordance with the publisher copyright policy