Regulation of L-type Ca(V)1.3 channel activity and insulin secretion by the cGMP-PKG signaling pathway Journal Article

Authors: Sandoval, A.; Duran, P.; Gandini, M. A.; Andrade, A.; Almanza, A.; Kaja, S.; Felix, R.
Article Title: Regulation of L-type Ca(V)1.3 channel activity and insulin secretion by the cGMP-PKG signaling pathway
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 Ca(2+) currents in rat vestibular hair cells and chromaffin cells. This current allegedly flow through voltage-gated Ca(V)1.3L-type Ca(2+) 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 Ca(V)1.3 channels heterologously expressed in HEK-293 cells, are regulatory targets of the cGMP-PKG signaling cascade. Our results indicate that the Ca(V)?(1) ion-conducting subunit of the Ca(V)1.3 channels is highly expressed in RIN-m5F cells and that the application of 8-Br-cGMP, a membrane-permeable analogue of cGMP, significantly inhibits Ca(2+) 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 Ca(V)1.3 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 Ca(V)?(1) pore-forming subunit of the channel. These findings unveil a novel mechanism for how the cGMP-PKG signaling pathway may regulate Ca(V)1.3 channels and contribute to regulate insulin secretion.
Journal Title: Cell calcium
Volume: 66
ISSN: 1532-1991
Publisher: Elsevier Inc  
Date Published: 2017
Start Page: 1
End Page: 9
Language: eng
Notes: LR: 20181113; CI: Copyright © 2017; GR: R00 MH099405/MH/NIMH NIH HHS/United States; JID: 8006226; 0 (Calcium Channels, L-Type); 0 (Carbazoles); 0 (Insulin); 0 (Protein Subunits); 126643-37-6 (KT 5823); 31356-94-2 (8-bromocyclic GMP); 31C4KY9ESH (Nitric Oxide); EC (Cyclic GMP-Dependent Protein Kinases); H2D2X058MU (Cyclic GMP); NIHMS934132; OTO: NOTNLM; 2017/03/07 00:00 [received]; 2017/04/03 00:00 [revised]; 2017/05/12 00:00 [accepted]; 2017/08/16 06:00 [entrez]; 2017/08/16 06:00 [pubmed]; 2018/04/24 06:00 [medline]; ppublish