Establishment of transgenic rat expressing human A or B Transferase gene and cloning of rat paralogous genes equivalent of human histo-blood group ABO gene.

组织血型ABH抗原不仅对输血很重要，而且对器官移植也很重要。为了改善移植的临床管理，发展ABO不相合的动物模型是可取的。与小鼠相比，大鼠的体型较大，更适合于器官移植的常规检查。为了评估大鼠作为动物模型的可行性，我们研究了大鼠ABO同源基因，建立了人A和B转移酶转基因大鼠。从Wistar大鼠基因组DNA中扩增出人ABO基因外显子7的DNA片段，并进行了序列测定。以扩增片段为探针进行Southern杂交，在EcoRI和BamHI消化的7个品系的基因组上都出现了多条杂交条带，表现出品系间条带数目的差异。从一只Wistar大鼠中克隆了4个cDNA，其中3个具有A-转移酶活性，1个具有B-转移酶活性。这些活性依赖于人ABO转移酶第266位和268位的等值残基。野生Wistar大鼠在唾液腺、肠道和膀胱组织中表达A抗原，但B抗原在所研究的任何器官中均未染色，而具有B转移酶活性的ABO同源物的转录本普遍存在。将人A-转移酶和B-转移酶转移到Wistar大鼠体内。A转基因大鼠在脑丛、II型肺上皮、胰腺和表皮的异位组织中表达A抗原。B转基因大鼠的B抗原在与A转基因大鼠相同的器官中表达。如果类人ABO祖先基因像大鼠一样由具有A和B转移酶活性的多拷贝基因组成，它们必须相互捐赠或接受彼此的基因片段，并可能产生一个由A等位基因和B等位基因组成的基因座。这一估计必须通过对大鼠和其他哺乳动物的进一步基因组计划来解决。

Histo-blood group ABH antigens are important not only for blood transfusion but also for organ transplantation. To improve the clinical management of transplantation, development of ABO-mismatched animal models is desirable. Rats are more suitable for ordinary examination of organ transplantation because of the larger body size compared with mice. To evaluate the availability of rats as an animal model, we studied rat ABO homologue and established human A- and B-transferase transgenic rats. A DNA fragment corresponding to exon 7 of the human ABO gene was amplified from Wistar rat genomic DNA and sequenced. Using the amplified fragments as a probe for Southern blotting, multiple hybridized bands appeared on both EcoRI and BamHI digested genomes of seven rat strains, which showed variations in the band numbers among the strains. Four cDNAs were cloned from a Wistar rat, three of which showed A-transferase activity and one of which showed B-transferase activity. These activities were dependent on the equivalent residues at 266 and 268 of human ABO transferase. Wild Wistar rats expressed A-antigen in salivary gland, intestine, and urinary bladder tissue, but B-antigen was not stained in any organs studied, while a transcript from the ABO homologue with B-transferase activity was ubiquitous. Human A-transferase and B-transferase were transferred into Wistar rats. A-transgenic rats expressed A-antigen in ectopic tissue of the brain plexus, type II lung epithelium, pancreas, and epidermis. B-antigen in the B-transgenic rat was expressed in the same organs as A-transgenic rats. If the hominoid ABO ancestral genes consisted of multicopy genes with A and B transferase activity like rats, they must donate or accept gene fragments from each other and may produce a locus composed of A-alleles and B-alleles. This estimation must be resolved by further genome projects in rats and other mammals.