Analyses of polymorphisms in the FUT2 and FUT3 and mechanism of synthesis of Lewis blood group antigens

点击翻译按钮获取中文摘要

We identified 24 SNPs containing seven novel SNPs (three of them are inactivating mutations) in the coding region of the FUT2 in Ovambos, Turks, and Mongolian populations. The genetic variations observed in these populations were similar to that of neighboring ones and seemed to reflect the geographic background and history of human migration. During screening of the se^<fus>, a Sec1-FUT2-Sec1 hybrid allele was identified in a Mongolian sample. This result implies that we need to be careful in choosing PCR primers otherwise make false-positive typing of se^<fus> because of recombinant alleles, while this allele is rare. By analysis the promoter region of the FUT2, we found African-specific SNPs with high incidence that affected transcriptional activity in culture cells. It is possible that long linkage disequilibrium (LD) block containing this region in African populations and the upstream region is also under balancing selection as an independent block of coding region.To elucidate the location of the Lewis and Se enzymes that regulate the synthesis of Lewis antigens in Golgi apparatus, we constructed chimeric genes, FUT23 and FUT32 that exchanged the N-terminal cytoplasmic regions of the FUT2 and FUT3. We observed higher expression of the Le^a than that of Le^b antigens on the COS-7 transfectants of FUT23 and FUT32 comparing to which of FUT2 and FUT3. This observation suggests that the localization of two enzymes is important for the expression of the Lewis antigens and the cytoplasmic domains contain the signal of that. We are under investigation of subcellular localization of the enzymes encoded by the fusion proteins with fluorescent proteins and the variations of the coding region of the FUT3 in several human populations.