Characterization of the 5′-noncoding region of the mouse choline acetyltransferase gene in transgenic mice

Choline acetyltransferase (ChAT) is a specific phenotypic marker of cholinergic neurons. Previous reports showed that different upstream regions of the ChAT gene are necessary for cell-type specific expression of reporter genes in cholinergic cell lines. The identity of the mouse ChAT promoter region controlling the establishment, maintenance, and plasticity of the cholinergic phenotype in vivo is not known. We characterized the promoter region of the mouse ChAT gene in transgenic mice, using β-galactosidase (β-gal) as a reporter. A 3401-bp segment from the 5′-untranslated region of the mouse ChAT gene was sufficient to direct the expression of β-gal to selected neurons of the nervous system (NS); it did not provide cholinergic specificity A larger fragment (∼6 Kb) of this region encompassing most of the coding sequence for the putative mouse vesicular acetylcholine transporter (VAChT) contained within the first intron of the ChAT gene, directs correct developmental and tissue-specific expression to cholinergic cells in transgenic mice. This fragment targeted β-gal expression only to cholinergic regions of the NS of transgenic mice, including basal forebrain, striatum, cortex, brain stem, and exclusively to α-motor neurons in the ventral horn of the spinal cord. This ChAT promoter will allow targeting of specific gene products to cholinergic neurons, in order to develop animal models for human diseases where injury and degeneration of chotinergic neurons is involved.