Novel splice variants of PACAP gene in mouse cerebellar granule cells

The mouse pituitary adenylate cyclase activating polypeptide (PACAP) gene consists of two alternative exons (1A and 1B) and four exons including the coding region. By the usage of alternative exons, three transcripts can be produced. In this report, however, we found that at least five preproPACAP transcripts, including two novel types, were produced in mouse cerebellar granule cells (CGCs) and their expression was induced by the Ca²⁺ influx through L-type voltage-dependent Ca²⁺ channels. The splicing occurred between the 3′-donor site of exon 1A and the two novel internal 5′-acceptor sites of exon 1B. These findings suggest that preproPACAP transcripts are produced by the complicated usage of the 5′-untranslated region in an activity-dependent manner.