Calcium current modulation by the γ 1 subunit depends on alternative splicing of Ca V 1.1
Calcium current modulation by the γ 1 subunit depends on alternative splicing of Ca V 1.1
Abstract The skeletal muscle voltage-gated calcium channel (CaV1.1) primarily functions as voltage sensor for excitation-contraction coupling. Conversely, its ion-conducting function is modulated by multiple mechanisms within the pore-forming α1S subunit and the auxiliary α2δ-1 and γ1 subunits. Particularly, developmentally regulated alternative splicing of exon 29, which inserts 19 amino acids in the extracellular IVS3-S4 loop of CaV1.1a, greatly reduces the current density and shifts the voltage-dependence of activation to positive potentials outside the physiological range. We generated a new HEK293-cell line stably expressing α2δ-1, β3, and STAC3. When the adult (CaV1.1a) and the embryonic (CaV1.1e) splice variants were expressed in these cells, the difference in the voltage-dependence of activation observed in muscle cells was reproduced, but not the reduced current density of CaV1.1a. Only when we further co-expressed the γ1 subunit, the current density of CaV1.1a, but not of CaV1.1e, was reduced by >50 %. In addition, γ1 caused a shift of the voltage-dependence of inactivation to negative voltages in both variants. Thus, the current-reducing effect of γ1, but not its effect on inactivation, is specifically dependent on the inclusion of exon 29 in CaV1.1a. Molecular structure modeling revealed several direct ionic interactions between oppositely charged residues in the IVS3-S4 loop and the γ1 subunit. However, substitution of these residues by alanine, individually or in combination, did not abolish the γ1-dependent reduction of current density, suggesting that structural rearrangements of CaV1.1a induced by inclusion of exon 29 allosterically empower the γ1 subunit to exert its inhibitory action on CaV1.1 calcium currents. SummaryEl Ghaleb et al. analyzed the effects of the γ1 subunit on current properties and expression of the adult (CaV1.1a) and embryonic (CaV1.1e) calcium channel splice variants, demonstrating that γ1 reduces the current amplitude in a splicing-dependent manner.
Ortner Nadine J.、Posch Wilfried、Monteleone Stefania、Draheim Henning J.、Wilflingseder Doris、Striessnig J?rg、Flucher Bernhard E.、Tuluc Petronel、Campiglio Marta、El Ghaleb Yousra、Liedl Klaus R.、Fern¨￠ndez-Quintero Monica L.、Tuinte Wietske E.
Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of InnsbruckInstitut of Hygiene and Medical Microbiology, Medical University of InnsbruckInstitute of General, Inorganic and Theoretical Chemistry, University of Innsbruck||Evotec (UK) Ltd.Boehringer Ingelheim Pharma GmbH & Co KG, CNS ResearchInstitut of Hygiene and Medical Microbiology, Medical University of InnsbruckDepartment of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of InnsbruckDepartment of Physiology and Medical Biophysics, Medical University InnsbruckDepartment of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of InnsbruckDepartment of Physiology and Medical Biophysics, Medical University InnsbruckDepartment of Physiology and Medical Biophysics, Medical University InnsbruckInstitute of General, Inorganic and Theoretical Chemistry, University of InnsbruckInstitute of General, Inorganic and Theoretical Chemistry, University of InnsbruckDepartment of Physiology and Medical Biophysics, Medical University Innsbruck
基础医学生理学分子生物学
Ortner Nadine J.,Posch Wilfried,Monteleone Stefania,Draheim Henning J.,Wilflingseder Doris,Striessnig J?rg,Flucher Bernhard E.,Tuluc Petronel,Campiglio Marta,El Ghaleb Yousra,Liedl Klaus R.,Fern¨￠ndez-Quintero Monica L.,Tuinte Wietske E..Calcium current modulation by the γ 1 subunit depends on alternative splicing of Ca V 1.1[EB/OL].(2025-03-28)[2025-06-12].https://www.biorxiv.org/content/10.1101/2021.11.10.468074.点此复制
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