Inhibition of Cav3.2 T-type Calcium Channels by Its Intracellular I-II Loop.
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.
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, Plateforme de Vectorologie, Biocampus Montpellier CNRS UMS 3426, INSERM US009, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France.
Arnaud
A
Monteil
Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, UM 119, Neuroscience Paris Seine (NPS), Paris F-75005, France, CNRS UMR 8246, NPS, Paris F-75005, France, and INSERM, U1130, NPS, Paris F-75005, France.
Patrick
P
Chausson
Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, UM 119, Neuroscience Paris Seine (NPS), Paris F-75005, France, CNRS UMR 8246, NPS, Paris F-75005, France, and INSERM, U1130, NPS, Paris F-75005, France.
Katia
K
Boutourlinsky
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France.
Alexandre
A
Mezghrani
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France.
Sylvaine
S
Huc-Brandt
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France.
Iulia
I
Blesneac
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France.
Isabelle
I
Bidaud
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, Plateforme de Vectorologie, Biocampus Montpellier CNRS UMS 3426, INSERM US009, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France.
Céline
C
Lemmers
Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, UM 119, Neuroscience Paris Seine (NPS), Paris F-75005, France, CNRS UMR 8246, NPS, Paris F-75005, France, and INSERM, U1130, NPS, Paris F-75005, France.
Nathalie
N
Leresche
Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, UM 119, Neuroscience Paris Seine (NPS), Paris F-75005, France, CNRS UMR 8246, NPS, Paris F-75005, France, and INSERM, U1130, NPS, Paris F-75005, France.
Régis C
RC
Lambert
From the Université de Montpellier, CNRS UMR 5203, Département de Physiologie, Institut de Génomique Fonctionnelle, Montpellier, F-34094 France, INSERM, U1191, Montpellier, F-34094 France, LabEx "Ion Channel Science and Therapeutics," Montpellier, F-34094 France, philippe.lory@igf.cnrs.fr.
Philippe
P
Lory
D000818:Animals; D001921:Brain / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009474:Neurons / Q000378:metabolism; D017433:Protein Structure, Secondary; D051381:Rats; D017208:Rats, Wistar
C121855:CACNA1G protein, human; C479952:CACNA1H protein, human; C469757:CACNA1I protein, human; D020747:Calcium Channels, T-Type
Cav3.2; HEK-293T cell line; Sindbis virus; T-type calcium channels; Western blot; calcium channel; neuroblastoma; neuron; patch clamp; thalamic neurons