Tissue and cell-type specific expression of a splice variant in the II-III cytoplasmic loop of Cacna1b

Presynaptic CaV2.2 (N-type) channels are fundamental for transmitter release across the nervous system. The gene encoding CaV2.2 channels, Cacna1b, contains alternatively spliced exons that originate functionally distinct splice variants (e18a, e24a, e31a and 37a/37b). Alternative splicing of the cassette exon 18a generates two mRNA transcripts (+e18a-Cacna1b and Δe18a-Cacna1b). In this study, using novel mouse genetic models and in situ hybridization (BaseScopeTM), we confirmed that +e18a-Cacna1b splice variants are expressed in monoaminergic regions of midbrain. We expanded these studies and identified +e18a-Cacna1b mRNA in deep cerebellar cells and spinal cord motor neurons. Furthermore, we determined that +e18a-Cacna1b is enriched in cholecystokinin expressing interneurons. Our results provide key information to understand cell-specific functions of CaV2.2 channels.