Wang Yuxia, Boeck Andreea Ticu, Duysen Ellen G, Van Keuren Margaret, Saunders Thomas L, Lockridge Oksana
University of Nebraska Medical Center, Eppley Institute, Omaha, NE 68198-6805, USA.
Toxicol Appl Pharmacol. 2004 May 1;196(3):356-66. doi: 10.1016/j.taap.2003.12.018.
Organophosphorus toxicants (OP) include chemical nerve agents and pesticides. The goal of this work was to find out whether an animal could be made resistant to OP toxicity by genetic engineering. The human butyrylcholinesterase (BChE) mutant G117H was chosen for study because it has the unusual ability to hydrolyze OP as well as acetylcholine, and it is resistant to inhibition by OP. Human G117H BChE, under the control of the ROSA26 promoter, was expressed in all tissues of transgenic mice. A stable transgenic mouse line expressed 0.5 microg/ml of human G117H BChE in plasma as well as 2 microg/ml of wild-type mouse BChE. Intestine, kidneys, stomach, lungs, heart, spleen, liver, brain, and muscle expressed 0.6-0.15 microg/g of G117H BChE. Transgenic mice were normal in behavior and fertility. The LD50 dose of echothiophate for wild-type mice was 0.1 mg/kg sc. This dose caused severe cholinergic signs of toxicity and lethality in wild-type mice, but caused no deaths and only mild toxicity in transgenic animals. The mechanism of protection was investigated by measuring acetylcholinesterase (AChE) and BChE activity. It was found that AChE and endogenous BChE were inhibited to the same extent in echothiophate-treated wild type and transgenic mice. This led to the hypothesis that protection against echothiophate toxicity was not explained by hydrolysis of echothiophate. In conclusion, the transgenic G117H BChE mouse demonstrates the factors required to achieve protection from OP toxicity in a vertebrate animal.
有机磷毒物（OP）包括化学神经毒剂和杀虫剂。这项工作的目的是弄清楚是否可以通过基因工程使动物对OP毒性产生抗性。选择人类丁酰胆碱酯酶（BChE）突变体G117H进行研究，因为它具有水解OP以及乙酰胆碱的特殊能力，并且对OP的抑制具有抗性。在ROSA26启动子的控制下，人类G117H BChE在转基因小鼠的所有组织中表达。一个稳定的转基因小鼠品系在血浆中表达0.5微克/毫升的人类G117H BChE以及2微克/毫升的野生型小鼠BChE。肠道、肾脏、胃、肺、心脏、脾脏、肝脏、大脑和肌肉表达0.6 - 0.15微克/克的G117H BChE。转基因小鼠在行为和生育能力方面正常。野生型小鼠对依可碘酯的半数致死剂量（LD50）为0.1毫克/千克皮下注射。该剂量在野生型小鼠中引起严重的胆碱能毒性体征和致死性，但在转基因动物中未导致死亡，仅引起轻度毒性。通过测量乙酰胆碱酯酶（AChE）和BChE活性来研究保护机制。发现在依可碘酯处理的野生型和转基因小鼠中，AChE和内源性BChE受到相同程度的抑制。这导致了一个假设，即对依可碘酯毒性的保护不能通过依可碘酯的水解来解释。总之，转基因G117H BChE小鼠证明了在脊椎动物中实现对OP毒性保护所需的因素。
