Spatial diversity in gene expression for VDCCγ subunit family in developing and adult mouse brains

The γ subunit of voltage-dependent Ca2+ channels (VDCCs) is characterized by molecular diversity and regulation of AMPA-type glutamate receptors as well as VDCCs. In the present study, we examined expressions for the VDCCγ1-8 subunit mRNAs in developing and adult mouse brains by in situ hybridization. In adult brains, the γ2 and γ7 subunit mRNAs were widely expressed in various grey matter regions with the highest level in cerebellar Purkinje cells and granule cells. The γ3 and γ8 subunit mRNAs predominated in the telencephalon, with the latter being at striking levels in the hippocampus. The γ4 subunit mRNA was enriched in the olfactory bulb, striatum, thalamus and hypothalamus. The γ5 subunit mRNA was abundant in the olfactory bulb, hippocampal CA2, thalamus, inferior colliculus and Bergmann glia. Transcripts of these subunits were detected in embryonic brains: some showed well-preserved spatial patterns (γ2, γ5, γ7 and γ8), while others underwent developmental up- (γ3) or down-regulation (γ4). In contrast, the γ1 and γ6 subunit mRNAs were negative or very low throughout brain development. Therefore, the present study has revealed spatial diversity in gene expression for individual VDCCγ subunits, presumably reflecting functional diversity of this protein family and their differential involvement in neural function.