Zhu Hao-Jie, Patrick Kennerly S, Yuan Hong-Jie, Wang Jun-Sheng, Donovan Jennifer L, DeVane C Lindsay, Malcolm Robert, Johnson Julie A, Youngblood Geri L, Sweet Douglas H, Langaee Taimour Y, Markowitz John S
Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA.
Am J Hum Genet. 2008 Jun;82(6):1241-8. doi: 10.1016/j.ajhg.2008.04.015. Epub 2008 May 15.
The human carboxylesterase 1 (CES1) gene encodes for the enzyme carboxylesterase 1, a serine esterase governing both metabolic deactivation and activation of numerous therapeutic agents. During the course of a study of the pharmacokinetics of the methyl ester racemic psychostimulant methylphenidate, profoundly elevated methylphenidate plasma concentrations, unprecedented distortions in isomer disposition, and increases in hemodynamic measures were observed in a subject of European descent. These observations led to a focused study of the subject's CES1 gene. DNA sequencing detected two coding region single-nucleotide mutations located in exons 4 and 6. The mutation in exon 4 is located in codon 143 and leads to a nonconservative substitution, p.Gly143Glu. A deletion in exon 6 at codon 260 results in a frameshift mutation, p.Asp260fs, altering residues 260-299 before truncating at a premature stop codon. The minor allele frequency of p.Gly143Glu was determined to be 3.7%, 4.3%, 2.0%, and 0% in white, black, Hispanic, and Asian populations, respectively. Of 925 individual DNA samples examined, none carried the p.Asp260fs, indicating it is an extremely rare mutation. In vitro functional studies demonstrated the catalytic functions of both p.Gly143Glu and p.Asp260fs are substantially impaired, resulting in a complete loss of hydrolytic activity toward methylphenidate. When a more sensitive esterase substrate, p-nitrophenyl acetate was utilized, only 21.4% and 0.6% catalytic efficiency (V(max)/K(m)) were determined in p.Gly143Glu and p.Asp260fs, respectively, compared to the wild-type enzyme. These findings indicate that specific CES1 gene variants can lead to clinically significant alterations in pharmacokinetics and drug response of carboxylesterase 1 substrates.
人类羧酸酯酶1（CES1）基因编码羧酸酯酶1，这是一种丝氨酸酯酶，可调控多种治疗药物的代谢失活和激活。在一项关于甲基酯外消旋精神兴奋药哌甲酯药代动力学的研究过程中，在一名欧洲血统受试者中观察到哌甲酯血浆浓度大幅升高、异构体分布出现前所未有的扭曲以及血流动力学指标增加。这些观察结果导致对该受试者的CES1基因进行重点研究。DNA测序检测到位于外显子4和6的两个编码区单核苷酸突变。外显子4中的突变位于密码子143，导致非保守性替换，即p.Gly143Glu。外显子6中密码子260处的缺失导致移码突变，即p.Asp260fs，在提前终止密码子处截断之前改变了260 - 299位的氨基酸残基。p.Gly143Glu的次要等位基因频率在白人、黑人、西班牙裔和亚洲人群中分别确定为3.7%、4.3%、2.0%和0%。在检测的925个个体DNA样本中，没有一个携带p.Asp260fs，表明它是一种极其罕见的突变。体外功能研究表明，p.Gly143Glu和p.Asp260fs的催化功能均受到严重损害，导致对哌甲酯的水解活性完全丧失。当使用更敏感的酯酶底物对硝基苯乙酸时，与野生型酶相比，p.Gly143Glu和p.Asp260fs的催化效率（V(max)/K(m)）分别仅为21.4%和0.6%。这些发现表明，特定的CES1基因变异可导致羧酸酯酶1底物的药代动力学和药物反应出现具有临床意义的改变。
