title: Functional genetic variants in the 3'-untranslated region of sulfotransferase isoform 1A1 (SULT1A1) and their effect on enzymatic activity.
abstract: Sulfotransferase isoform 1A1 (SULT1A1) is the most highly expressed hepatic sulfotransferase and is involved in the biotransformation of a wide variety of endo- and xenobiotics. A common single nucleotide polymorphism (SNP) in the coding region of SULT1A1, several proximal promoter SNPs, and copy number variation (CNV) are associated with altered enzymatic activity, but these variants do not fully account for the observed variation of SULT1A1 activity in human populations. In order to identify additional SNPs modulating SULT1A1 activity, we examined the 3'-untranslated region (UTR) of SULT1A1 in 97 liver samples. Direct sequencing revealed that two SNPs in the 3'-UTR (902A > G [rs6839] and 973C > T [rs1042157]) and one SNP in the 3'-flanking region (1307G > A [rs4788068]) were common. These SNPs are in absolute linkage disequilibrium with each other and in tight linkage with SULT1A1 1/2 (linkage coefficient D' 0.83) and are significantly associated with SULT1A1 messenger RNA (p = 0.001, 0.029, 0.021) and enzymatic activity (p = 0.022, 0.012, 0.027). We then examined the collective effects of 3'-UTR SNPs, SULT1A1 1/2, and CNV on SULT1A1 activity in 498 Caucasian and 127 African-American subjects by haplotype analysis. This analysis revealed that SULT1A1 1/2 does not contribute to the variation in SULT1A1 enzymatic activity when the 3'-UTR SNPs are included in the statistical model. Two major haplotypes (ACG and GTA) were significantly correlated with SULT1A1 activity, and when stratified by copy number, the SULT1A1 3'-UTR SNPs remain significantly associated with SULT1A1 enzymatic activity in Caucasians, but not in African-Americans. Subsequent functional characterization revealed that a microRNA, miR-631, regulates SULT1A1 expression in a genotype-specific manner.
authors.affiliation: Division of Medical Genetics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Yu
authors.forename: Ishwori B
authors.initials: IB
authors.lastname: Dhakal
authors.forename: Marjorie
authors.initials: M
authors.lastname: Beggs
authors.forename: Vineetha Koroth
authors.initials: VK
authors.lastname: Edavana
authors.forename: Suzanne
authors.initials: S
authors.lastname: Williams
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhang
authors.forename: Kelly
authors.initials: K
authors.lastname: Mercer
authors.forename: Baitang
authors.initials: B
authors.lastname: Ning
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Lang
authors.forename: Fred F
authors.initials: FF
authors.lastname: Kadlubar
authors.forename: Susan
authors.initials: S
authors.lastname: Kadlubar
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015239:Arylsulfotransferase / Q000235:genetics* / Q000378:metabolism; D001792:Blood Platelets / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation / Q000235:genetics; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008099:Liver / Q000201:enzymology; D008297:Male; D035683:MicroRNAs / Q000235:genetics; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*
chemical_list: D020413:3' Untranslated Regions; D035683:MicroRNAs; D015239:Arylsulfotransferase; C117544:SULT1A1 protein, human