title: Unusual regulation of splicing of the cholinergic locus in Caenorhabditis elegans.
abstract: The essential neurotransmitter acetylcholine functions throughout the animal kingdom. In Caenorhabditis elegans, the acetylcholine biosynthetic enzyme [choline acetyltransferase (ChAT)] and vesicular transporter [vesicular acetylcholine transporter (VAChT)] are encoded by the cha-1 and unc-17 genes, respectively. These two genes compose a single complex locus in which the unc-17 gene is nested within the first intron of cha-1, and the two gene products arise from a common pre-messenger RNA (pre-mRNA) by alternative splicing. This genomic organization, known as the cholinergic gene locus (CGL), is conserved throughout the animal kingdom, suggesting that the structure is important for the regulation and function of these genes. However, very little is known about CGL regulation in any species. We now report the identification of an unusual type of splicing regulation in the CGL of C. elegans, mediated by two pairs of complementary sequence elements within the locus. We show that both pairs of elements are required for efficient splicing to the distal acceptor, and we also demonstrate that proper distal splicing depends more on sequence complementarity within each pair of elements than on the sequences themselves. We propose that these sequence elements are able to form stem-loop structures in the pre-mRNA; such structures would favor specific splicing alternatives and thus regulate CGL splicing. We have identified complementary elements at comparable locations in the genomes of representative species of other animal phyla; we suggest that this unusual regulatory mechanism may be a general feature of CGLs.
authors.affiliation: Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104.
authors.forename: Eleanor A
authors.initials: EA
authors.lastname: Mathews
authors.affiliation: Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104.
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Mullen
authors.affiliation: Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104.
authors.forename: Jacob R
authors.initials: JR
authors.lastname: Manjarrez
authors.affiliation: Genetic Models of Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104 Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104 James-Rand@ouhsc.edu.
authors.forename: James B
authors.initials: JB
authors.lastname: Rand
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D002795:Choline O-Acetyltransferase / Q000235:genetics*; D019143:Evolution, Molecular; D032041:Nested Genes; D012326:RNA Splicing; D050494:Vesicular Acetylcholine Transport Proteins / Q000235:genetics*
chemical_list: D029742:Caenorhabditis elegans Proteins; C082365:Unc-17 protein, C elegans; D050494:Vesicular Acetylcholine Transport Proteins; D002795:Choline O-Acetyltransferase
keywords: ChAT; VAChT; choline acetyltransferase; cholinergic gene locus; vesicular acetylcholine transporter