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 (BaseScope™), 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.