title: Characterization of the in vitro transcriptional activity of polymorphic alleles of the human monoamine oxidase-B gene.
abstract: The activity of monoamine oxidase-B (MAO-B) enzyme has a high degree of heritability, although no common genetic polymorphisms are present in the MAO-B coding region. The only known polymorphisms in MAO-B gene are a C-1,114T in the 5' region, a variable number of GT repeats in intron 2, and a G/A change in intron 13. The genetically determined differences in MAO-B activity among subjects most likely derive from functional differences conferred by these three MAO-B genetic polymorphisms, or by polymorphisms in trans-acting factors that regulate MAO-B expression. In order to identify differences in transcriptional activity conferred by the MAO-B genetic variants, we cloned alternative alleles at the three polymorphic loci in -1,114, intron 2 and intron 13, and tested them in transfection-luciferase assays in HepG2 hepatoma and 1321N1 astrocytoma cells. The mutant -1,114 allele T had higher activity than allele C in both cell lines, when cloned in pGL3Enhancer. Significant differences in trascriptional activity by intron 2 GT repeat allele were also observed, and varied by cell type and reporter construct. Allele G of intron 13 had significantly higher activity than allele A in both cell lines. These results indicate transcriptional activity differences between MAO-B variant alleles that are naturally occurring in the population.
authors.affiliation: Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, 98105, USA. cstpla@u.washington.edu
authors.forename: Paola
authors.initials: P
authors.lastname: Costa-Mallen
authors.forename: Samir N
authors.initials: SN
authors.lastname: Kelada
authors.forename: Lucio G
authors.initials: LG
authors.lastname: Costa
authors.forename: Harvey
authors.initials: H
authors.lastname: Checkoway
mesh_terms: D000483:Alleles; D001254:Astrocytoma; D006528:Carcinoma, Hepatocellular; D045744:Cell Line, Tumor; D015870:Gene Expression / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007438:Introns; D008995:Monoamine Oxidase / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection / Q000379:methods
chemical_list: D012333:RNA, Messenger; D008995:Monoamine Oxidase