Targeting of embryonic and postnatal autonomic and enteric neurons with a vasoactive intestinal peptide transgene

The neuropeptide vasoactive intestinal peptide (VIP) is expressed in severa l distinct sites in the CNS, in cholinergic and enteric ganglia, and in a s mall subpopulation of neurons within sympathetic ganglia. Previous studies on the human VIP gene indicate that transcription in neural crest-derived n euroblastoma and pheochromocytoma cell lines is controlled in part by multi ple regulatory elements located along 4.5 kb of upstream 5' flanking sequen ce. In the current studies, transgenic mice were created with a chimeric ge ne consisting of 16.5 kb of the mouse VIP gene fused to the beta-galactosid ase reporter. In situ hybridization analysis in adult mice indicated that r eporter gene expression was correctly targeted to neurons in the esophagus, stomach, small intestine, and colon. No expression was observed in the bra in, including regions that contain abundant VIP-expressing cells, such as t he thalamus, amygdala, cerebral cortex, hippocampus, and suprachiasmatic nu cleus. Analysis of transgene expression in neonatal and embryonic day 13.5 mice revealed a near perfect correlation between VIP and beta-galactosidase gene expression in cranial cholinergic ganglia and the superior cervical g anglia, and lack of transgene expression in sensory ganglia and in nonneuro nal tissue. Potential ectopic transgene expression was observed in neonates , in the cerebellar external granule layer and in a small subpopulation of neurons in the olfactory epithelium, We conclude that the 16.5 kb of VIP ge ne used in these studies contains sequences sufficient for directing expres sion specifically to VIP neurons in the PNS, and that sequences located els ewhere on the gene are required for proper CNS expression. The VIP gene seq uences used here should be capable of targeting other gene products to spec ific populations of embryonic and adult peripheral neurons without causing significant expression in the CNS.