Abstract
In an attempt to study the pituitary adenylate cyclase-activating polypeptide (PACAP)-mediated signaling functions in vivo, we have used gene targeting in embryonic stem cells to disrupt exon 2 of the PACAP type I receptor (PAC1 receptor) gene, which contains the ATG translation start site and the signal peptide. Unexpectedly, active transcription of PAC1 receptor mRNA was detected in the mutant mice, although ligand binding in the brain was greatly reduced. PAC1 receptor exon 2-/- mice were apparently normal and fertile. The expression study of the mutant receptor lacking the signal peptide showed that the signal peptide is required for efficient cell surface expression and N-linked glycosylation of the PAC1 receptor. We also generated mice lacking PACAP ligand by targeted deletion of the PACAP gene exon 5. PACAP-null mice developed to adulthood at a frequency lower than expected by mendelian genetics, and were hyperactive and showed reduced anxiety. Neurochemical characterization of these mice is currently under investigation.
