SNP rs311103 is associated with human erythroid-specific Xg a /CD99 blood group phenotypes

• Main Authors: Ji-Ting Huang, 黃繼霆
• Other Authors: 余榮熾
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/m3b3z6

碩士 === 國立臺灣大學 === 生化科學研究所 === 105 === XG blood group system comprises two antigens, Xga and CD99. The Xga antigen express on the membranes of red blood cells (RBCs), and it can classify into Xg(a+) and Xg(a-) phenotype. The CD99 antigen express on membranes of many tissue cells, and it can classify into CD99-high (CD99H) and CD99-Low (CD99L) phenotype. According to past study, the Xga and CD99 antigens show a unique and sex-specific phenotypic relationship on the surface of RBCs. Among females and males, the Xg(a+) phenotype is associated with the CD99H phenotype. On the other hand, Xg(a–) females show an association with the CD99L phenotype; however, by way of contrast, Xg(a–) males, in addition to possibly having the CD99L phenotype, may also have the CD99H phenotype. There was no answer to explain why caused this phenomenon, so it attracted us to study what the mechanism of regulation between XG and CD99 genes. We initially conducted a pilot study involving targeted next-generation sequencing of the 570-kb genomic sequences relevant to XG and CD99 from 16 individuals with different Xga/CD99 phenotypes. This was followed by a larger-scale association study that demonstrated an association between SNP rs311103 and the Xga/CD99 blood groups. It has been found that the reticulocytes from Xg(a+)/CD99H individuals have a higher level of the XG and CD99 (MIC2) transcripts than the reticulocytes from Xg(a–)/CD99L individuals. Different genomic segment that encompasses polymorphic rs311103 was introduced into erythroid /non-erythroid lineage cell lines by reporter assay, and the polymorphic rs311103 genomic regions were analyzed using PROMO program to identify potential transcription factor binding motifs. Putative binding motifs for the GATA binding protein family and for lymphoid enhancer binding factor 1 (LEF1) were identified within the rs311103[G] region, but not within rs311103[C] region. Follow-up investigations included ectopic expression of various GATA factors, EMSA, and ChIP to show that the erythroid GATA1 factor is able to bind specifically to the rs311103[G] region and markedly stimulates the transcriptional activity of the rs311103[G] segment. In order to determine the details of the control system, especially their involvements in the co-regulation the XG and CD99 expressions and in the long-range interaction between the rs311103[G] genomic region and the CD99 promoter. Other study showed that GATA1/2 and TAL1 could co-regulate genes expression, the site-directed mutagenesis were conduct to know interaction between them. The present findings identify the genetic basis of the erythroid-specific Xga/CD99 blood group phenotypes and reveal the molecular background to their formation.