Neuron-specific expression of reporter gene in transgenic mice carrying the 5′-upstream region of mouse P/Q-type Ca channel α1A subunit gene fused to E. coli lacZ reporter gene

To dissect the molecular mechanisms underlying the neuron-specific expression of the P/Q type calcium channel α_1A subunit gene, transgenic mice carrying a 0.5-kb, 1.5-kb, 3.0-kb or 6.3-kb 5′-upstream region of the gene fused to Escherichia coli lacZ reporter gene were produced. In transgenic mice carrying the 1.5-kb, 3.0-kb or 6.3-kb 5′-upstream region, the reporter gene was exclusively expressed in the nervous system, although those with the 0.5-kb 5′-upstream region failed to show reporter expression. Histological examinations showed that the three 5′-upstream regions induced distinct expression patterns of the reporter gene in the CNS and adrenal medulla. The 1.5-kb 5′-upstream region drove reporter gene expression in the olfactory bulb, dorsal cortex and hippocampus, while the regulatory element for the expression in the amygdaloid nucleus, septum, habenula medial nucleus, choroid plexus, substantia nigra, inferior colliculus, pontine nucleus and cerebellum was located in the 5′-upstream sequence between 1.5 kb and 6.3 kb. In the cerebellum, the expression of the reporter gene was induced by the 3.0-kb region in granule cells, whereas it was induced by the 6.3-kb region in Purkinje cells. The expression of the reporter gene in chromaffin cells in the adrenal medulla was induced only by the 6.3-kb 5′-upstream region. These results suggest that the expression of the mouse P/Q-type Ca²⁺ channel α_1A subunit gene is regulated in a complex fashion by both positive and negative cis-regulatory elements.