Stimulation of recombinant Cav3.2, T‐type, Ca2+ channel currents by CaMKIIγC
- 1 January 2002
- journal article
- Published by Wiley in The Journal of Physiology
- Vol. 538 (2) , 343-355
- https://doi.org/10.1113/jphysiol.2001.012839
Abstract
Molecular cloning of low-voltage activated (LVA) T-type calcium channels has enabled the study of their regulation in heterologous expression systems. Here we investigate the regulation of Cav3.2 α1-subunits (α1H) by calcium- and/or calmodulin-dependent protein kinase II (CaMKII). 293 cells stably expressing α1H were transiently transfected with CaMKIIγC. Using the whole-cell recording configuration, we observed that elevation of pipette free Ca2+ (1 μm) in the presence of CaM (2 μm) increases T-type channel activity selectively at negative potentials, evoking an 11 mV hyperpolarizing shift in the half-maximal potential (V1/2) for activation. The V1/2 of channel inactivation is not altered by Ca2+/CaM. These effects reproduced modulation observed in adrenal zona glomerulosa cells. The potentiation by Ca2+/CaM was dependent on the co-expression of CaMKIIγC and required Ca2+/CaM-dependent kinase activity. Peptide (AIP) and lipophilic (KN-62) protein kinase inhibitors prevented the Ca2+/CaM-induced changes in channel gating without altering basal Cav3.2 channel activity (27 nm free Ca2+) as did replacing pipette ATP with adenylyl imidodiphosphate (AMP-PNP), a non-hydrolysable analogue. CaMKII-dependent potentiation of channel opening resulted in significant increases in apparent steady-state open probability (Po) and sustained channel current at negative voltages. Under identical conditions, CaMKII activation did not regulate the activity of Cav3.1 channels, the first cloned member (α1G) of the T-type Ca2+ channel family. Our results provide the first evidence for the differential regulation of two members of the Cav3 family by protein kinase activation and the first report reconstituting CaMKII-dependent regulation of any cloned Ca2+ channel.Keywords
This publication has 64 references indexed in Scilit:
- Molecular cloning and functional expression of Cav3.1c, a T‐type calcium channel from human brainFEBS Letters, 2000
- Structure and regulation of calcium/calmodulin-dependent protein kinases II and IVBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1996
- Identification of critical amino acids involved in α1‐β interaction in voltage‐dependent Ca2+ channelsFEBS Letters, 1996
- A G Protein Is Involved in the Angiotensin AT2 Receptor Inhibition of the T-Type Calcium Current in Non-differentiated NG108-15 CellsPublished by Elsevier ,1995
- Dopamine blocks T-type calcium channels in cultured rat adrenal glomerulosa cellsEndocrinology, 1994
- Phosphorylation of the L‐type calcium channel β subunit is involved in β‐adrenergic signal transduction in canine myocardiumFEBS Letters, 1993
- Dopamine modulates in a differential fashion T- and L-type calcium currents in bass retinal horizontal cells.The Journal of general physiology, 1993
- Calcium-dependent enhancement of calcium current in smooth muscle by calmodulin-dependent protein kinase IINature, 1992
- Effects of Dopamine on Voltage-Dependent Potassium Currents in Identified Rat Lactotroph CellsNeuroendocrinology, 1989
- Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ moleculesNature, 1989