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Open Access

A mouse model to study the C-terminal regulation of CaV1.3 L-type calcium channels

  • Anja Scharinger1,
  • Florian Hechenblaikner1,
  • Gabriella Bock1,
  • Mathias Gebhart1,
  • Kai Schönig2,
  • Dusan Bartsch2,
  • Anupam Sah1,
  • Nicolas Singewald1,
  • Martina J Sinnegger-Brauns1 and
  • Jörg Striessnig1Email author
BMC Pharmacology and Toxicology201213(Suppl 1):A50

DOI: 10.1186/2050-6511-13-S1-A50

Published: 17 September 2012

Background

CaV1.3 voltage-gated L-type Ca2+ channels (LTCCs) play an important role for hearing, cardiac pacemaking and neuronal excitability. The C-terminus of CaV1.3 tightly controls channel gating by an intramolecular protein interaction involving two putative α-helices (termed PCRD, DCRD), which form a C-terminal modulatory mechanism (CTM) only in full-length CaV1.3 variants. In short (CaV1.342A and CaV1.343S) CaV1.3 α1 subunit splice variants CTM is absent which leads to profound changes in channel gating: activation occurs at more negative voltages and Ca2+-dependent inactivation (CDI) is faster.

Methods

We quantified CaV1.3 splice variants by qPCR analysis and transcript scanning, using different mouse tissues. To assess the physiological relevance of CTM, we generated a mutant mouse strain in which CTM function is disrupted by an HA-tag (CaV1.3-DCRDHA/HA mice). We used anti-HA antibodies to detect the expression of the HA-tagged full length channel by Western blot analysis.

Results

The short variants CaV1.342A (highest relative abundance in substantia nigra (SN) and ventral tegmental area (VTA)) and CaV1.343S are both less abundant in mouse brain indicating that the full length form CaV1.3L comprises the most abundant form (about 50% of all transcripts). In mouse heart short transcripts are rare and CaV1.3L represents about 90% of all known transcripts. CaV1.3-DCRDHA/HA mice contain a homozygous interruption of the CTM by disrupting the DCRD helix with an HA-tag. We show that this induces "short" gating properties in this mutant full-length variant. Homozygous mice are viable and display no gross anatomical and functional abnormalities. Expression of the HA-tagged full-length channel could be detected in mouse whole brain membrane preparations. Heterozygous mice show no overt differences in locomotor activity during daytime.

Conclusions

We have successfully generated a mouse model which will enable us to study the physiological role of CTM function in vivo. It mimics the (permanent) pharmacological inhibition of CTM function and will thus allow predictions about its potential as a new drug target. Furthermore, the HA-tagged α1 subunit will provide a tool to specifically determine the expression of CaV1.3L channels with anti-HA antibodies in mouse tissues.

Declarations

Acknowledgements

Supported by the Austrian Science Fund project SFB f44, the EC project MRTN-CT-2006-35367 ("CavNet"), FWF 20670 and the University of Innsbruck.

Authors’ Affiliations

(1)
Department of Pharmacology and Toxicology, Institute of Pharmacy, and Center for Molecular Biosciences Innsbruck, University of Innsbruck
(2)
Department of Molecular Biology, Central Institute of Mental Health, University of Heidelberg

Copyright

© Scharinger et al; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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