Construction of expression vector from different transcripts of RHD gene / 中国实验血液学杂志

RHD gene has different alternative transcripts. This study was aimed to construct expression vector of normal mRNA, DEL9 and DEL89 transcripts from RHD gene. Total RNA was extracted from Rh(D) positive umbilical blood cells of newborn. Intact RhD cDNA, DEL9 and DEL89 transcripts were obtained by one-step and two-step RT-PCR, respectively. The obtained products were cloned into pCR4 TOPO sequencing vector for choosing the right transcript. RHD gene was amplified again from the sequencing plasmid DNA, and then subcloned into pcDNA3.1/V5-His TOPO expression vector; DEL9 and DEL89 were cloned into the expression vector directly. Gene sequence and direction were identified by sequencing. The results showed that the sequence and direction of target genes were right, thus these 3 different expression vectors were correctly constructed. It is concluded that expression vector is constructed from different transcripts of RHD gene, which lays a foundation for further exploring the membranous protein expression of Rh(D) antigen.

Molecular mechanism of an individual with weaken B phenotype in ABO blood group / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To elucidate the serological characteristics and molecular mechanism of a blood donor with weaken B antigen.</p><p><b>METHODS</b>The ABO blood group antigens on red blood cells were identified by monoclonal antibodies, the ABO antibodies in serum were detected by standard A, B, O cells and the activity of the B glycosyltransferase was analyzed. The full-length sequence and 5'-untranslated region (5'-UTR) sequence of ABO gene were amplified by polymerase chain reaction (PCR) respectively and direct sequencing. The alternative splicing isoforms of ABO cDNA were obtained by reverse transcription-PCR(RT-PCR) and analyzed with cloning and sequencing techniques. The level of methylation of the CpG island in ABO gene promoter was analyzed by bisulfite sequencing method.</p><p><b>RESULTS</b>The serological characteristic of the donor showed that the B antigen was decreased obviously without anti-B antibodies in serum and the B glycosyltransferase activity was decreased as well. The genotype of the donor was B101/O01 without any other mutations in the full-length coding sequences and splice receptor sites. The nucleotide characteristics of the 5'-UTR was consistent with B101/O01 and no any abnormity was identified in the promoter, enhancer and the negative regulatory sequence regions. The integrative cDNA transcript of ABO gene was obtained and no new splicing isoform was found. Compared with the normal B phenotype, a number of methylated CpG sites were found near the promoter of ABO gene in this sample.</p><p><b>CONCLUSION</b>The methylation in the CpG island of ABO gene promoter region may cause weak expression of the B antigen.</p>

Study on the expression stability of mutant alpha-1,2 fucosyltransferase gene 293C to T and 658C to T in eukaryotic cells / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish the eukaryotic cell expression system for the alpha-1,2 fucosyltransferase gene FUT1 293C to T and 658C to T mutations and explore the mechanism of FUT1 mutations resulting in the reduced expression of H antigen.</p><p><b>METHODS</b>Genomic DNAs were extracted from individuals with para-Bombay phenotype and full coding region of FUT1 was amplified. The amplification fragments were ligated with pcDNA3.1 plasmid to construct the recombinant expression vectors. The recombinant plasmids were transfected into the COS-7 cells using lipofectamine transfection reagent and stable expression screening was performed. FUT1 mRNA expression was determined by real-time quantitative PCR. The activity of enzyme was measured by high performance liquid chromatography. Expressed protein was identified by SDS-PAGE and Western blotting.</p><p><b>RESULTS</b>pcDNA3.1-FUT1 wildtype, pcDNA3.1-FUT1 293C to T and pcDNA3.1-FUT1 658C to T recombinant vectors were constructed, respectively. COS-7 cells with stable expression of FUT1 were obtained through recombinant plasmid transfection and screening with G418. The FUT1 mRNA level of transfected cells with 293C to T and 658C to T recombinant vectors reached 97.10% and 104.74% of the wildtype FUT1 transfected cell. A specific protein band with about 46 000 was confirmed in the transfected cell lysates by SDS-PAGE electrophoresis and Western blotting with 6×His Tag antibody. The wildtype FUT1 transfected cell lysates can catalyze the enzymatic reaction, while the enzyme activity of cell lysates from 293C to T and 658C to T were abolished.</p><p><b>CONCLUSION</b>The results suggested that the 293C to T and 658C to T mutations of FUT1 gene did not affect the RNA and protein expression levels, but the enzyme activity of cells with FUT1 mutations was significantly decreased which resulted in the reduced expressin of H antigen.</p>

Identification of an ABx09 phenotype of ABO subtype / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the molecular basis for an individual with ABx09 phenotype of ABO subtype.</p><p><b>METHODS</b>The ABO group antigens on red blood cells of the proband were identified by monoclonal antibodies, and the ABO antibody in serum was detected by standard A, B, O cells. The exons 1 to 7 of ABO gene were amplified by polymerase chain reaction (PCR) respectively and the PCR products were sequenced directly. The amplified products for exons 5 to 7 were also cloned by TOPO TA cloning sequencing kit to split the two alleles apart, selected colonies were sequenced bidirectionally for exons 5 to 7 of the ABO gene. The samples of the proband's parents were collected, then serological test of the blood group and sequence analysis for exons 6 and 7 of ABO gene were preformed.</p><p><b>RESULTS</b>Both A and B antigens were detected on red blood cells of the proband and there was anti-B antibody in the serum. There was no G deletion at position 261, while 297AG in exon 6, 467CT, 526CG, 657CT, 703GA, 796CA, 803GC, 889GA and 930GA heterozygote in exon 7 were detected by direct DNA sequencing, which can be assigned for A102Bx09 genotype. After cloning and sequencing, two alleles A102 and Bx09 were obtained. The sequence of Bx09 had one nucleotide changes (G to A) at position 889 compared with that of B101, which resulted in an amino acid change of Glu to Lys at 297 position. The Bx09 in the proband was inherited from her mother by family investigation.</p><p><b>CONCLUSION</b>G to A at nt889 of alpha-1,3 galactosyltransferasegene can result in Bx09 phenotype, with the presence of anti-B antibody in serum.</p>

Study on polymorphism of membrane glycoprotein genes related to human platelet alloantigens / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the polymorphisms of platelet membrane glycoprotein genes related to human platelet alloantigen (HPA)-1 to 17w.</p><p><b>METHODS</b>The DNA segments of platelet membrane glycoprotein genes related to HPA-1 to 17w were amplified using author's designed primers. The amplification products were purified and directly sequenced to identify the HPA genotype and glycoprotein gene polymorphisms.</p><p><b>RESULTS</b>Thirteen new single nucleotide polymorphisms (SNPs) and a micro-satellite sequence were found in the glycoprotein genes from the 112 random samples, in which two SNPs (1333G/A and 1960G/A) in ITGB3 gene result in two amino acid change (V419M and E628K) on glycoprotein GPIIIa.</p><p><b>CONCLUSION</b>New variants in platelet membrane glycoprotein genes were identified, which may lead to structure change of platelet membrane glycoprotein and affect the accuracy of partial HPA genotyping method.</p>

Analysis of alpha-1,2-fucosyltransferase gene mutations in a Chinese family with para-Bombay phenotype / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the molecular genetic basis of para-Bombay phenotype in a Chinese family.</p><p><b>METHODS</b>ABO and H phenotypes of the proband and his pedigree were characterized by serological techniques. The exons 6 and 7 of the ABO gene and full coding region of alpha-1,2-fucosyltransferase (FUT1) gene of the pedigree were analyzed by polymerase chain reaction and direct sequencing of the amplified fragments. The haplotypes of compound heterozygote of the FUT1 gene were also analyzed by cloning sequencing.</p><p><b>RESULTS</b>Three para-Bombay phenotypes were identified in nine family members by serological technology. Three heterozygous variants (35C/T, 235G/C and 682A/G) were found in FUT1 gene of the proband, and the hapotype of FUT1 gene was h(235C)/h(35T+628G)according to the cloning sequencing. The alleles h(235C)and h(35T+628G) caused G79R, A12V and M228V amino acid substitutions in alpha-1,2-fucosyltransferase, respectively.</p><p><b>CONCLUSION</b>A novel 235G>C mutation of FUT1 gene which was associated with para-Bombay phenotype was found in the Chinese pedigree.</p>

Cloning and expression of MHC class I chain-related gene A in E. coli / 中国实验血液学杂志

In order to construct prokaryotic expression system of MHC classI chain-related gene A (mica) and purify MICA protein, RNAs were extracted from the peripheral blood samples and mica cDNA fragments were obtained by RT-PCR method. The cDNA for mica was ligated with cloning vector by TOPO method. The recombinant cloning vector and prokaryotic expression vector pET-28a were digested by two restriction enzymes and ligated to construct pET-28a-MICA recombinant expression vector, then the pET-28a-MICA vector was transformed and expressed in E. coli BL21 DE3. The recombinant protein was purified by Ni-NTA Spin method. The results showed that the recombinant MICA protein expressed with soluble form in host with pET-28a-MICA vector after IPTG induction. The recombinant target protein was obtained by Ni-NTA spin purification. In conclusion, this study has constructed prokaryotic expression system of mica gene and has purified MICA protein which would help to explore the interaction between MICA and transplantation immunology.

Molecular basis of a new O61 allele in ABO blood group / 中国实验血液学杂志

Objective of this study was to explore the molecular basis of a new O61 allele in ABO blood group. The ABO group antigens on red cells of the blood samples were identified by monoclonal antibodies and the ABO antibody in serum was detected by the standard A, B, O red cells. The coding region sequences of exon 5 to exon 7 in ABO gene were amplified by polymerase chain reaction (PCR) and the amplification products were purified with double enzyme digestion and directly sequenced for exon 6 and 7. The diploid of the individual with B phenotype was separated into its haploid components with a haplotype specific extraction method. The exons 6 to 7 of the two single ABO haplotypes were then amplified and sequenced separately. The results indicated that 3 samples had mutation at 743 site in total 417 individuals, in which 2 individuals were with O phenotype and 1 individual was with B phenotype. The DNA sequencing of exon 6 and 7 in 2 samples with O phenotype showed 261G deletion and 743G/C heterozygotes. The DNA sequencing of exon 6 and 7 in the sample with B phenotype showed 261G/deletion and 297A/G, 526C/G, 743G/C, 657C/T, 703G/A, 796C/A, 803G/C, 930G/A heterozygotes. After separating of the 2 single strands in the B sample with haplotype specific extraction, an O and B101 allele were identified after sequencing. The novel allele was submitted to the Blood Group Antigen Gene Mutation database and is named as O61. It is concluded that 743G>C is a novel mutation in exon 7 of ABO and a novel O61 allele with 743G>C has been identified.

Molecular genetic analysis of a new B112 allele of ABO blood group / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the molecular genetic basis for a new B112 allele of ABO blood group and the pedigree of the proband.</p><p><b>METHODS</b>The ABO group antigens on red cells of the proband were identified by monoclonal antibodies. The ABO antibody in serum was detected by using standard A, B and O cells. The exons 5-7 of ABO gene for the proband was amplified by polymerase chain reaction and the amplified products were digested with double enzymes and sequenced for exons 6 and 7. A magnetic bead-based, haplotype specific extraction was used to separate the diploid sample of the proband into its haploid components. The exons 6 and 7 of the two single ABO haplotypes were then amplified and sequenced separately. The samples of the parents of the proband were collected, and the blood group serological test and sequence analysis for exons 6 and 7 of ABO gene were performed.</p><p><b>RESULTS</b>The serum characteristic of the proband was consisted with the normal B phenotype. The DNA sequencing of exons 6 and 7 showed 261G/del, 297A/G, 526C/G, 559C/T, 657C/T, 703G/A, 796C/A, 803G/C and 930G/A heterozygotes and was assigned for B/O genotype. After separation of the two single strands of the proband with haplotype specific extraction, a B112 and an O01 allele were identified after sequencing. The B112 allele had one nucleotide change (C to T) at position 559 compared with B101, which resulted in an amino acid change at position 187 (Arg to Cys). The B112 in the proband was identified to inherit from his mother after pedigree analysis, the ABO blood group serological characteristics and sequences of exons 6 and 7 of the mother were identical to that of the proband.</p><p><b>CONCLUSION</b>A novel B112 allele of ABO group system with 559C>T was identified. It had normal B antigen expression, suggesting that Arg118Cys of alpha-1, 3 galactosyltransferase did not affect its enzyme activity.</p>