The 129XA → C polymorphism in methylenetetrahydrofolate reductase (MTHFR):: in vitro expression and association with homocysteine
The 129XA → C polymorphism in methylenetetrahydrofolate reductase (MTHFR):: in vitro expression and association with homocysteine
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DOI：
10.1016/s0021-9150(00)00671-7
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发表时间：
2001-06-01
期刊：
影响因子：
5.3
通讯作者：
Rozen, R
中科院分区：
文献类型：
--
作者：
Weisberg, IS;Jacques, PF;Rozen, R
亚甲基四氢叶酸还原酶（MTHFR）的一种常见突变，677 C-> T，与酶活性降低（一种不耐热酶）和轻度高同型半胱氨酸血症（血管疾病的一个危险因素）相关。最近，第二种常见的突变（1298 A--> C;谷氨酸变成丙氨酸）被报道，但这种突变仅在携带bp 677变体的个体中被认为会增加同型半胱氨酸。为了评估这种突变的功能后果，我们进行了定点诱变和体外表达。对于临床影响的体内评估，我们检查了来自NHLBI家族心脏研究的198名个体的1298 A--> C基因型和血浆同型半胱氨酸，这些个体先前已经评估了677替代。进行人cDNA的定点诱变以产生含有两种突变中的每一种的酶，以及含有两种取代的酶。在细菌提取物中评估酶活性和热不稳定性。将野生型cDNA的活性指定为100%;分别含有1298和677个突变的突变酶分别具有对照活性的68%（+/-5.0）和45%（+/-10.8），而含有两个突变的酶具有对照活性的41%（+/-12.8）。1298突变与不耐热酶无关。在家族心脏研究中，与仅携带677 C-> T变异的个体相比，两种变异杂合子个体的空腹同型半胱氨酸显著更高（P < 0.05）。这项研究表明，MTHFR中的两个变异应被评估为高同型半胱氨酸血症的遗传危险因素。(C)2001爱思唯尔科学爱尔兰有限公司保留所有权利。
A common mutation in methylenetetrahydrofolate reductase (MTHFR), 677C --> T, is associated with reduced enzyme activity, a thermolabile enzyme and mild hyperhomocysteinemia, a risk factor for vascular disease. Recently, a second common mutation (1298A --> C; glutamate to alanine) was reported, but this mutation was suggested to increase homocysteine only in individuals who carried the bp677 variant. To evaluate the functional consequences of this mutation, we performed site-directed mutagenesis and in vitro expression. For in vivo assessment of clinical impact, we examined the 1298A --> C genotypes and plasma homocysteine in 198 individuals from the NHLBI Family Heart Study that had previously been assessed for the 677 substitution. Site-directed mutagenesis of the human cDNA was performed to generate enzymes containing each of the two mutations, as well as an enzyme containing both substitutions. Enzyme activity and thermolability were assessed in bacterial extracts. The activity of the wild-type cDNA was designated as 100%; mutant enzymes containing the 1298 and 677 mutations separately had 68% (+/- 5.0) and 45% (+/- 10.8), respectively, of control activity while the enzyme containing both mutations had 41% (+/- 12.8) of control activity. The 1298 mutation was not associated with a thermolabile enzyme. In the Family Heart Study, fasting homocysteine was significantly higher (P < 0.05) in individuals heterozygous for both substitutions, compared to individuals who carried only the 677C --> T variant. This study suggests that two variants in MTHFR should be assessed as genetic risk factors for hyperhomocysteinemia. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.