Infection-associated FUT2 (Fucosyltransferase 2) genetic variation and impact on functionality assessed by in vivo studies
Infection-associated FUT2 (Fucosyltransferase 2) genetic variation and impact on functionality assessed by in vivo studies
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DOI：
10.1007/s10719-009-9255-8
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发表时间：
2010-01-01
影响因子：
3
通讯作者：
David, Leonor
中科院分区：
文献类型：
--
作者：
Silva, Lara M.;Carvalho, Ana S.;David, Leonor
分泌型(Se)/非分泌型（Se）组织血型差异取决于FUT2酶的作用，对人类对感染的易感性具有重要意义。为了表征FUT2变异的功能，我们评估了来自葡萄牙北部的67个个体的唾液表型与FUT2基因序列变异之间的相关性。虽然大多数非分泌单倍型被发现携带与739G > A错义替换相关的428G > A无义突变，但我们也在Se表型个体中发现了携带739*A等位基因和高效428*G变异的重组单倍型。这一发现表明，与之前的结果相反，739*A等位基因编码了一个有效的Se等位基因。为了验证这一假设，我们使用FACS（荧光激活细胞分选）分析和2型和3型链H结构的表达，评估了CHO-K1细胞瞬时转染中全编码表达构建体的体内酶活性。我们检测了739*A表达结构的FUT2活性，表明739G > A替代确实没有失活。根据FUT2处于长期平衡选择的假设，我们估计FUT2全球遗传变异的时间深度可达300万年。对特定变异的年龄估计表明，428G > A突变至少发生在187万年前，而739G > A突变大约发生在81.6万年前。导致东亚人无分泌表型的385A > T错义突变似乎是最近发生的，可能发生在大约25.6万年前。
The secretor (Se)/nonsecretor (se) histo-blood group variation depends on the action of the FUT2 enzyme and has major implications for human susceptibility to infections. To characterize the functionality of FUT2 variants, we assessed the correlation between saliva phenotypes and sequence variation at the FUT2 gene in sixty seven individuals from northern Portugal. While most non-secretor haplotypes were found to carry the 428G > A nonsense mutation in association with a 739G > A missense substitution, we have also identified a recombinant haplotype carrying the 739*A allele together with the efficient 428*G variant in individuals with the Se phenotype. This finding suggested, in contrast to previous results, that the 739*A allele encodes an efficient Se allele. To test this hypothesis we evaluated the in vivo enzyme activity of full coding expression constructs in transient transfection of CHO-K1 cells using FACS (fluorescence-activated cell sorting) analysis and expression of type 2 and type 3 chain H structures as read out. We detected FUT2 activity for the 739*A expression construct, demonstrating that the 739G > A substitution is indeed not inactivating. In accordance with the hypothesis that FUT2 is under long standing balancing selection, we estimated that the time depth of FUT2 global genetic variation is as old as 3 million years. Age estimates of specific variants suggest that the 428G > A mutation occurred at least 1.87 million years ago while the 739G > A substitution is about 816,000 years old. The 385A > T missense mutation underlying the non-secretor phenotype in East Asians appears to be more recent and is likely to have occurred about 256,000 years ago.