CaV1.2 and CaV1.3 voltage-gated L-type Ca2+ channels in rat white fat adipocytes

Fedorenko, Olena A.; Pulbutr, Pawitra; Banke, Elin; Akaniro-Ejim, Nneoma E.; Bentley, Donna C.; Olofsson, Charlotta S.; Chan, Sue; Smith, Paul A.

Abstract

L-type channel antagonists are of therapeutic benefit in the treatment of hyperlipidaemia and insulin resistance. Our aim was to identify L-type voltage-gated Ca2+ channels in white fat adipocytes, and determine if they affect intracellular Ca2+, lipolysis and lipogenesis. We used a multidisciplinary approach of molecular biology, confocal microscopy, Ca2+ imaging and metabolic assays to explore this problem using adipocytes isolated from adult rat epididymal fat pads. CaV1.2, CaV1.3 and CaV1.1 alpha1, beta and alpha2delta subunits were detected at the gene expression level. The CaV1.2 and CaV1.3 alpha1 subunits were identified in the plasma membrane at the protein level. Confocal microscopy with fluorescent antibodies labelled CaV1.2 in the plasma membrane. Ca2+ imaging revealed that the intracellular Ca2+ concentration, [Ca2 +]i was reversibly decreased by removal of extracellular Ca2+, an effect mimicked by verapamil, nifedipine and Co2+, all blockers of L-type channels, whereas the Ca2+ channel agonist BAY-K8644 increased [Ca2+]i. The finding that the magnitude of these effects correlated with basal [Ca2+]i suggests that adipocyte [Ca2+]i is controlled by L-type Ca2+ channels that are constitutively active at the adipocyte depolarized membrane potential. Pharmacological manipulation of L-type channel activity modulated both basal and catecholamine-stimulated lipolysis but not insulin-induced glucose uptake or lipogenesis. We conclude that white adipocytes have constitutively active L-type Ca2+ channels which explains their sensitivity of lipolysis to Ca2+ channel modulators. Our data suggest CaV1.2 as a potential novel therapeutic target in the treatment of obesity.

Citation

Fedorenko, O. A., Pulbutr, P., Banke, E., Akaniro-Ejim, N. E., Bentley, D. C., Olofsson, C. S., …Smith, P. A. (2020). CaV1.2 and CaV1.3 voltage-gated L-type Ca2+ channels in rat white fat adipocytes. Journal of Endocrinology, 244(2), 369–381. https://doi.org/10.1530/joe-19-0493

• Journal Article Type: Article
• Acceptance Date: Nov 21, 2019
• Online Publication Date: Dec 26, 2019
• Publication Date: Feb 1, 2020
• Deposit Date: Jan 21, 2020
• Publicly Available Date: Dec 27, 2020
• Journal: Journal of Endocrinology
• Print ISSN: 0022-0795
• Electronic ISSN: 1479-6805
• Publisher: BioScientifica
• Peer Reviewed: Peer Reviewed
• Volume: 244
• Issue: 2
• Pages: 369–381
• DOI: https://doi.org/10.1530/joe-19-0493
• Keywords: Endocrinology, Diabetes and Metabolism; Endocrinology
• Public URL: https://nottingham-repository.worktribe.com/output/3776817
• Publisher URL: https://joe.bioscientifica.com/view/journals/joe/244/2/JOE-19-0493.xml
• Additional Information: Disclaimer: this is not the definitive version of record of this article. This manuscript has been accepted for publication in Journal of Endocrinology, but the version presented here has not yet been copy-edited, formatted or proofed. Consequently, Bioscientifica accepts no responsibility for any errors or omissions it may contain. The definitive version is now freely available at https://doi.org/10.1530/JOE-19-0493. 2020.