Cloning of the rat gene encoding choline acetyltransferase, a cholinergic neuron-specific marker.

Abstract

The neurotransmitter acetylcholine is synthesized by choline acetyltransferase (ChAT; EC 2.3.1.6). Since the expression of ChAT in the nervous system is restricted to cholinergic neurons, it serves as a specific marker for these neurons. In Alzheimer disease, ChAT activity is markedly reduced in the affected brain areas. Nerve growth factor can increase the ChAT activity of brain cholinergic neurons in vitro and in vivo. We have cloned the rat ChAT gene and identified one 5' noncoding exon and 14 exons that account for the entire coding sequence. The exon organization is compared with the protein domains conserved during evolution. These exons are distributed over at least 64 kilobases in the rat genome; the largest intron is at least 14 kilobases long. Within a 0.7-kilobase region immediately upstream of the confirmed sequence of the noncoding exon, TATA-like elements and numerous potential binding sites for transcription factors are found, including AP-1, Sp1, octamer-binding factor(s), CTF/NF-1, and the nuclear oncoprotein Myb.

Aberrant Patterning of Neuromuscular Synapses in Choline Acetyltransferase-Deficient Mice

“…Although the genomic structure of mouse Chat has not been described, it is known that in rats and humans, ChAT is encoded by a large gene that includes 14 coding exons in the 3Ј region that are used in all transcripts. In contrast, the 5Ј region of the gene is complicated, with alternative splicing, multiple transcription and translation start sites, and the gene encoding the vesicular ACh transporter embedded in the first intron (Hahn et al, 1992;Ohno et al, 2001). To avoid this 5Ј region, the catalytic portion of the protein was targeted for deletion.…”

The Cholinergic Gene Locus

“…The mammalian cholinergic gene locus thetic nerve terminals occurs very early postnatally is arrayed similarly to that of Drosophila, with the . It has been hypothesized preentire YAChT coding region contained within a single viously that cholinergic sympathetic innervation of major exon (Bejanin et al, 1994;, sweat glands occurs via a "switch" from a noradrener-1994), and ChAT encoded by at least 14 rather than gic to a cholinergic phenotype that is dependent on just nine exons as in the worm (Hahn et a!., 1992). nerve terminal interactions with the sweat gland itself…”

Cloning and characterization of the choline acetyltransferase structural gene (cha-1) from C. elegans

“…Conserved domains and exon boundaries. The exon boundaries for C. eleguns ChAT (10 introns), Drosophila ChAT (7 introns; Sugihara et al,199 l), and rat ChAT (introns 2-14; Hahn et al, 1992) are superimposed on the sequence identity profile in Figure 8. In general, no clear relationship appears to exist between the domains of conserved sequence and the exon structures of any of these ChAT genes, although all of the exons except the first two contain at least one conserved domain.…”