Referenced in: none

Automatically associated channels: Cav3.1 , Cav3.2 , Cav3.3

Title: Inhibition of Cav3.2 T-type Calcium Channels by Its Intracellular I-II Loop.

Authors: Arnaud Monteil, Patrick Chausson, Katia Boutourlinsky, Alexandre Mezghrani, Sylvaine Huc-Brandt, Iulia Blesneac, Isabelle Bidaud, Céline Lemmers, Nathalie Leresche, Régis C Lambert, Philippe Lory

Journal, date & volume: J. Biol. Chem., 2015 Jun 26 , 290, 16168-76

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25931121

Abstract
Voltage-dependent calcium channels (Cav) of the T-type family (Cav3.1, Cav3.2, and Cav3.3) are activated by low threshold membrane depolarization and contribute greatly to neuronal network excitability. Enhanced T-type channel activity, especially Cav3.2, contributes to disease states, including absence epilepsy. Interestingly, the intracellular loop connecting domains I and II (I-II loop) of Cav3.2 channels is implicated in the control of both surface expression and channel gating, indicating that this I-II loop plays an important regulatory role in T-type current. Here we describe that co-expression of this I-II loop or its proximal region (Δ1-Cav3.2; Ser(423)-Pro(542)) together with recombinant full-length Cav3.2 channel inhibited T-type current without affecting channel expression and membrane incorporation. Similar T-type current inhibition was obtained in NG 108-15 neuroblastoma cells that constitutively express Cav3.2 channels. Of interest, Δ1-Cav3.2 inhibited both Cav3.2 and Cav3.1 but not Cav3.3 currents. Efficacy of Δ1-Cav3.2 to inhibit native T-type channels was assessed in thalamic neurons using viral transduction. We describe that T-type current was significantly inhibited in the ventrobasal neurons that express Cav3.1, whereas in nucleus reticularis thalami neurons that express Cav3.2 and Cav3.3 channels, only the fast inactivating T-type current (Cav3.2 component) was significantly inhibited. Altogether, these data describe a new strategy to differentially inhibit Cav3 isoforms of the T-type calcium channels.