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Cell Calcium. 2017 Sep;66:1-9. doi: 10.1016/j.ceca.2017.05.008. Epub 2017 May 15.

Regulation of L-type CaV1.3 channel activity and insulin secretion by the cGMP-PKG signaling pathway.

Author information

1
FES Iztacala UNAM, Tlalnepantla De Baz, Mexico.
2
Departamento de Biología Celular, Cinvestav-IPN, Ciudad de México, Mexico.
3
Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
4
Department of Biological Sciences, University of New Hampshire, Durham, NH, USA.
5
Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría, Ramón de la Fuente Muñiz, Ciudad de México, Mexico.
6
Department of Ophtalmology and Molecular Pharmacology & Therapeutics, Loyola University, Chicago, Strich School of Medicine, Maywood, IL, USA.
7
Departamento de Biología Celular, Cinvestav-IPN, Ciudad de México, Mexico. Electronic address: rfelix@cinvestav.mx.

Abstract

cGMP is a second messenger widely used in the nervous system and other tissues. One of the major effectors for cGMP is the serine/threonine protein kinase, cGMP-dependent protein kinase (PKG), which catalyzes the phosphorylation of a variety of proteins including ion channels. Previously, it has been shown that the cGMP-PKG signaling pathway inhibits Ca2+ currents in rat vestibular hair cells and chromaffin cells. This current allegedly flow through voltage-gated CaV1.3L-type Ca2+ channels, and is important for controlling vestibular hair cell sensory function and catecholamine secretion, respectively. Here, we show that native L-type channels in the insulin-secreting RIN-m5F cell line, and recombinant CaV1.3 channels heterologously expressed in HEK-293 cells, are regulatory targets of the cGMP-PKG signaling cascade. Our results indicate that the CaVα1 ion-conducting subunit of the CaV1.3 channels is highly expressed in RIN-m5F cells and that the application of 8-Br-cGMP, a membrane-permeable analogue of cGMP, significantly inhibits Ca2+ macroscopic currents and impair insulin release stimulated with high K+. In addition, KT-5823, a specific inhibitor of PKG, prevents the current inhibition generated by 8-Br-cGMP in the heterologous expression system. Interestingly, mutating the putative phosphorylation sites to residues resistant to phosphorylation showed that the relevant PKG sites for CaV1.3 L-type channel regulation centers on two amino acid residues, Ser793 and Ser860, located in the intracellular loop connecting the II and III repeats of the CaVα1 pore-forming subunit of the channel. These findings unveil a novel mechanism for how the cGMP-PKG signaling pathway may regulate CaV1.3 channels and contribute to regulate insulin secretion.

KEYWORDS:

Cav channels; Insulin; L-type channels; PKG; Rin-m5F cells; cGMP

PMID:
28807144
PMCID:
PMC5776030
DOI:
10.1016/j.ceca.2017.05.008
[Indexed for MEDLINE]
Free PMC Article

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