Mukherjee Baidehi, Salavaggione Oreste E, Pelleymounter Linda L, Moon Irene, Eckloff Bruce W, Schaid Daniel J, Wieben Eric D, Weinshilboum Richard M
Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Drug Metab Dispos. 2006 Jul;34(7):1237-46. doi: 10.1124/dmd.106.009613. Epub 2006 Apr 25.
Glutathione S-transferase omega 1 and omega 2 (GSTO1 and GSTO2) catalyze monomethyl arsenate reduction, the rate-limiting reaction in arsenic biotransformation. As a step toward pharmacogenomic studies of these phase II enzymes, we resequenced human GSTO1 and GSTO2 using DNA samples from four ethnic groups. We identified 31 and 66 polymorphisms in GSTO1 and GSTO2, respectively, with four nonsynonymous-coding single nucleotide polymorphisms (cSNPs) in each gene. There were striking variations among ethnic groups in polymorphism frequencies and types. Expression constructs were created for all eight nonsynonymous cSNPs, as well as a deletion of codon 155 in GSTO1, and those constructs were used to transfect COS-1 cells. Quantitative Western blot analysis, after correction for transfection efficiency, showed a reduction in protein level of greater than 50% for the GSTO1 Tyr32 variant allozyme compared with wild type (WT), whereas levels for the Asp140, Lys208, Val236, and codon 155 deletion variant constructs were similar to that of the WT. For GSTO2, the Tyr130 and Ile158 variant allozymes showed 50 and 84% reductions in levels of expression, respectively, compared with WT, whereas the Ile41 and Asp142 allozymes displayed levels similar to that of WT GSTO2. Rabbit reticulocyte lysate degradation studies showed that the GSTO1 Tyr32 and the GSTO2 Tyr130, Ile158, and Asp142/Ile158 variant allozymes were degraded more rapidly than were their respective WT allozymes. These observations raise the possibility of functionally significant pharmacogenomic variation in the expression and function of GSTO1 and GSTO2.
谷胱甘肽S-转移酶ω1和ω2（GSTO1和GSTO2）催化一甲基砷酸盐的还原反应，这是砷生物转化中的限速反应。作为对这些II期酶进行药物基因组学研究的一步，我们使用来自四个种族群体的DNA样本对人类GSTO1和GSTO2进行了重测序。我们分别在GSTO1和GSTO2中鉴定出31个和66个多态性位点，每个基因中有四个非同义编码单核苷酸多态性（cSNP）。种族群体之间在多态性频率和类型上存在显著差异。针对所有八个非同义cSNP以及GSTO1中密码子155的缺失构建了表达载体，并使用这些载体转染COS-1细胞。在校正转染效率后进行的定量蛋白质印迹分析表明，与野生型（WT）相比，GSTO1 Tyr32变体同工酶的蛋白质水平降低了50%以上，而Asp140、Lys208、Val236和密码子155缺失变体构建体的水平与WT相似。对于GSTO2，与WT相比，Tyr130和Ile158变体同工酶的表达水平分别降低了50%和84%，而Ile41和Asp142同工酶的水平与WT GSTO2相似。兔网织红细胞裂解物降解研究表明，GSTO1 Tyr32以及GSTO2 Tyr130、Ile158和Asp142/Ile158变体同工酶比各自的WT同工酶降解得更快。这些观察结果增加了GSTO1和GSTO2的表达和功能在药物基因组学方面存在功能显著差异的可能性。
