Alternative splicing in the C-terminal tail of Cav2.1 is essential for preventing a neurological disease in mice.

Abstract

Alternative splicing (AS) that occurs at the final coding exon (exon 47) of the Cav2.1 voltage-gated calcium channel (VGCC) gene produces two major isoforms in the brain, MPI and MPc. These isoforms differ in their splice acceptor sites; human MPI is translated into a polyglutamine tract associated with spinocerebellar ataxia type 6 (SCA6), whereas MPc splices to an immediate stop codon, resulting in a shorter cytoplasmic tail. To gain insight into the functional role of the AS in vivo and whether modulating the splice patterns at this locus can be a potential therapeutic strategy for SCA6, here we created knockin mice that exclusively express MPc by inserting the splice-site mutation. The resultant Cacna1aCtmKO/CtmKO mice developed non-progressive neurological phenotypes, featuring early-onset ataxia and absence seizure without significant alterations in the basic properties of the channel. Interactions of Cav2.1 with Cavβ4 and Rimbp2 were significantly reduced while those with GABAB2 were enhanced in the cerebellum of Cacna1aCtmKO/CtmKO mice. Treatment with the GABAB antagonist CGP35348 partially rescued the motor impairments seen in Cacna1aCtmKO/CtmKO mice. These results suggest that the carboxyl-terminal domain of Cav2.1 is not essential for maintaining the basic properties of the channel in the cerebellar Purkinje neurons but is involved in multiple interactions of Cav2.1 with other proteins, and plays an essential role in preventing a complex neurological disease.

• Authors: Tomonori Aikawa, Takaki Watanabe, Taisuke Miyazaki, Takayasu Mikuni, Minoru Wakamori, Miyano Sakurai, Hidenori Aizawa, Nobutaka Ishizu, Masahiko Watanabe, Masanobu Kano, Hidehiro Mizusawa, Kei Watase
• Journal: Human molecular genetics (Hum Mol Genet) Vol. 26 Issue 16 Pg. 3094-3104 (08 15 2017) ISSN: 1460-2083 [Electronic] England
• PMID: 28510727 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected].

Chemical References

• Calcium Channels
• Calcium Channels, N-Type
• RNA Isoforms
• RNA Splice Sites
• voltage-dependent calcium channel (P-Q type)

Topics

• Alternative Splicing
• Animals
• Calcium Channels (genetics, metabolism)
• Calcium Channels, N-Type (genetics, metabolism)
• Cerebellum (metabolism)
• Exons
• Gene Knock-In Techniques
• Humans
• Mice
• Nervous System Diseases (genetics, metabolism)
• Purkinje Cells (metabolism)
• RNA Isoforms
• RNA Splice Sites
• Spinocerebellar Ataxias (genetics)