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

Presynaptic Ca_V 2.2 (N-type) channels are fundamental for transmitter release across the nervous system. The gene encoding Ca_V 2.2 channels, Cacna1b, contains alternatively spliced exons that result in functionally distinct splice variants (e18a, e24a, e31a, and 37a/37b). Alternative splicing of the cassette exon 18a generates two mRNA transcripts (+e18a-Cacna1b and ∆e18a-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 the 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 Ca_V 2.2 channels.