Tissue-specific expression of the human neuropeptide Y gene in transgenic mice

Neuropeptide Y (NPY) is the most abundant neuropeptide detected in the mammalian brain, and is found throughout the central and peripheral nervous system. This peptide is a proposed regulator of appetite, blood pressure, and pituitary hormone release. Previous experiments have demonstrated the ability of 5' sequences within the human NPY gene to promote transcription in cultured neuronal cells. To identify sequences in this gene that regulate tissue-specific expression, a NPY/CAT fusion gene, containing approximately 850 bp of NPY sequences, was microinjected into fertilized mouse ova. Five lines of transgenic mice were derived from these ova and several tissues from mice of each line were tested for transgene expression using the CAT assay. One line demonstrated X-chromosome-linked transmission of the transgene while the other lines demonstrated autosomally-linked transmission. Three lines demonstrated transgene expression with significant levels of CAT activity detectable only in tissues which have been shown to express endogenous NPY. One autosomally-linked line did not demonstrate significant levels of transgene activity because the transgene appeared to have undergone structural alteration during genomic integration. No transgene activity was detected in either male of female mice from the X-linked line, suggesting a positional regulation of the transgene locus other than X-inactivation in this line. The present research demonstrated the NPY regulatory sequences included in pCATNPY delta 796 sufficiently directed tissue-appropriate gene expression in transgenic mice.