Ducky mouse phenotype of epilepsy and ataxia is associated with mutations in the Cacna2d2 gene and decreased calcium channel current in cerebellar Purkinje cells.

J Neurosci
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Keywords
Abstract

The mouse mutant ducky, a model for absence epilepsy, is characterized by spike-wave seizures and ataxia. The ducky gene was mapped previously to distal mouse chromosome 9. High-resolution genetic and physical mapping has resulted in the identification of the Cacna2d2 gene encoding the alpha2delta2 voltage-dependent calcium channel subunit. Mutations in Cacna2d2 were found to underlie the ducky phenotype in the original ducky (du) strain and in a newly identified strain (du(2J)). Both mutations are predicted to result in loss of the full-length alpha2delta2 protein. Functional analysis shows that the alpha2delta2 subunit increases the maximum conductance of the alpha1A/beta4 channel combination when coexpressed in vitro in Xenopus oocytes. The Ca(2+) channel current in acutely dissociated du/du cerebellar Purkinje cells was reduced, with no change in single-channel conductance. In contrast, no effect on Ca(2+) channel current was seen in cerebellar granule cells, results consistent with the high level of expression of the Cacna2d2 gene in Purkinje, but not granule, neurons. Our observations document the first mammalian alpha2delta mutation and complete the association of each of the major classes of voltage-dependent Ca(2+) channel subunits with a phenotype of ataxia and epilepsy in the mouse.

Year of Publication
2001
Journal
J Neurosci
Volume
21
Issue
16
Pages
6095-104
Date Published
2001 Aug 15
ISSN
1529-2401
PubMed ID
11487633
Links
Grant list
NS31348 / NS / NINDS NIH HHS / United States
NS32801 / NS / NINDS NIH HHS / United States