β-Cell CaV channel regulation in physiology and pathophysiology

SN Yang, PO Berggren - American Journal of Physiology …, 2005 - journals.physiology.org
SN Yang, PO Berggren
American Journal of Physiology-Endocrinology And Metabolism, 2005journals.physiology.org
The β-cell is equipped with at least six voltage-gated Ca2+ (CaV) channel α1-subunits
designated CaV1. 2, CaV1. 3, CaV2. 1, CaV2. 2, CaV2. 3, and CaV3. 1. These principal
subunits, together with certain auxiliary subunits, assemble into different types of CaV
channels conducting L-, P/Q-, N-, R-, and T-type Ca2+ currents, respectively. The β-cell
shares customary mechanisms of CaV channel regulation with other excitable cells, such as
protein phosphorylation, Ca2+-dependent inactivation, and G protein modulation. However …
The β-cell is equipped with at least six voltage-gated Ca2+ (CaV) channel α1-subunits designated CaV1.2, CaV1.3, CaV2.1, CaV2.2, CaV2.3, and CaV3.1. These principal subunits, together with certain auxiliary subunits, assemble into different types of CaV channels conducting L-, P/Q-, N-, R-, and T-type Ca2+ currents, respectively. The β-cell shares customary mechanisms of CaV channel regulation with other excitable cells, such as protein phosphorylation, Ca2+-dependent inactivation, and G protein modulation. However, the β-cell displays some characteristic features to bring these mechanisms into play. In islet β-cells, CaV channels can be highly phosphorylated under basal conditions and thus marginally respond to further phosphorylation. In β-cell lines, CaV channels can be surrounded by tonically activated protein phosphatases dominating over protein kinases; thus their activity is dramatically enhanced by inhibition of protein phosphatases. During the last 10 years, we have revealed some novel mechanisms of β-cell CaV channel regulation under physiological and pathophysiological conditions, including the involvement of exocytotic proteins, inositol hexakisphosphate, and type 1 diabetic serum. This minireview highlights characteristic features of customary mechanisms of CaV channel regulation in β-cells and also reviews our studies on newly identified mechanisms of β-cell CaV channel regulation.
American Physiological Society