DNA sequence polymorphism at the human tumor necrosis factor (TNF) locus. Numerous TNF/lymphotoxin alleles tagged by two closely linked microsatellites in the upstream region of the lymphotoxin (TNF-beta) gene.
DNA sequence polymorphism at the human tumor necrosis factor (TNF) locus. Numerous TNF/lymphotoxin alleles tagged by two closely linked microsatellites in the upstream region of the lymphotoxin (TNF-beta) gene.
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人类肿瘤坏死因子 (TNF) 位点的 DNA 序列多态性。
DOI：
10.4049/jimmunol.147.3.1053
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发表时间：
1991
影响因子：
4.4
通讯作者：
R. Turetskaya
中科院分区：
文献类型：
--
作者：
S. Nedospasov;I. Udalova;D. Kuprash;R. Turetskaya
TNF-α和TNF-β（LT，TNF-β）基因串联排列，并在MHC着丝粒内映射到HLA-B，在端粒内映射到III类基因。由这些基因编码的两种细胞因子都是有效的免疫调节剂。另一方面，一些MHC连锁的自身免疫性疾病的特征在于其表达或诱导的异常水平。对假定的疾病相关的TNF/LT等位基因的搜索依赖于TNF基因座上的信息性遗传标记。以前，在人TNF基因座的遗传多态性程度较低，主要是双等位基因RFLP。为了定位和定义额外的多态性标记，我们用合成的串联重复的二核苷酸探测了基因组克隆的集合，对应于称为微卫星的序列。我们映射和表征三个（TC/GA）和一个（AC/GT）重复克隆40 kb的DNA，包括人TNF基因座。使用聚合酶链反应为基础的技术，我们分析了这四个微卫星，并观察其长度的多态性。使用来自献血者、两个家庭和三个人类细胞系的DNA样本，我们检测到邻近人类TNF基因的AC/GT微卫星的13个不同等位基因。通过同时分析第二个连锁微卫星进一步增加了变异性。这个连锁的TC/GA重复序列至少有5个等位基因，而位于LT（TNF-β）基因第一内含子的多态性最低的TC/GA重复序列有2个等位基因。TNF等位基因定义的微卫星是稳定的遗传和分离的孟德尔方式。因此，我们描述了迄今为止人类MHC这一部分DNA序列多态性的最具信息量的水平。我们提出了一个命名为微卫星标记的LT/TNF等位基因的大小和变异性的基础上，这也可以扩展到包括RFLP和其他尚未确定的多态性标记。微卫星标记的多态性，这里描述可以用于系统的连锁研究的HLA相关疾病。
TNF-alpha and lymphotoxin (LT, TNF-beta) genes are tandemly arranged and map within the MHC centromeric to HLA-B and telomeric to the class III genes. Both cytokines encoded by these genes are potent immunomodulators. On the other hand, some MHC-linked autoimmune diseases are characterized by abnormal levels of their expression or inducibility. A search for the putative disease-associated TNF/LT alleles depends on the informative genetic markers at the TNF locus. Previously, a low degree of genetic polymorphism at the human TNF locus has been reported, mostly bi-allelic RFLP. To localize and define additional polymorphic markers, we probed the collection of genomic clones with synthetic tandemly repeated dinucleotides, corresponding to the sequences known as microsatellites. We mapped and characterized three (TC/GA) and one (AC/GT) repeats within cloned 40-kb DNA comprising the human TNF locus. Using a polymerase chain reaction-based technique, we analyzed three of these four microsatellites and observed their length of polymorphism. Using DNA samples from blood donors, two families, and three human cell lines, we detected 13 distinct alleles of the AC/GT microsatellite neighboring human TNF genes. The variability was further increased by simultaneous analysis of the second linked microsatellite. This linked TC/GA repeat showed at least five alleles, whereas the least polymorphic TC/GA repeat located in the first intron of LT (TNF-beta) gene had two alleles. TNF alleles defined by microsatellites were stably inherited and segregated in the Mendelian way. Therefore, we describe thus far the most informative level of DNA sequence polymorphism in this part of human MHC. We propose a nomenclature for microsatellite tagged LT/TNF alleles based on their size and variability, which could also be extended to include RFLP and other not yet identified polymorphic markers. Microsatellite tagged polymorphism described here can be used in systematic linkage studies of HLA-associated diseases.