Molecular studies on genomic imprinting at APRT locus

APRT位点基因组印记的分子研究

• 批准号: 07457127
• 负责人: KAMATANI Naoyuki
• 金额: $ 2.05万
• 依托单位: Tokyo Women's Medical College
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07457127/
• 关键词: somatic mutation; purine metabolism; loss of heterozygosity; tumor suppressing gene; gene therapy; familial tumor; adenine phosphoribosyltransferase; プリント代謝; 体細胞遺伝子; ジャームライン遺伝子; 突然変異率; クローン生物; Loss of heterozygosity; プリン代謝; ゲノムインプリント; LOH /

Studies on in vivo somatic mutations at the adenine phosphoribosyltransferase (APRT) locus have disclosed that human somatic cells have mutations at surprisingly high frequencies. Most of the mutations are of the loss of heterozygosity (LOH) type. However, in 3 heterozygotes for APRT deficiency, LOH was not observed suggesting the genomic imprinting at this region. Precise analyzes, however, clarified that the genomic imprinting was not observed in this area, but the 3 persons had a unique deletion mutation which suppressed the occurrence of LOH.By the techniques of selective PCR and inverse PCR,the germline mutation suppressing LOH phenomenon was analyzed. This mutation gene (APRT^<**>del) had a deletion from the intron 4 and was ligated to an unknown gene. The determination of the sequence of the recombination site disclosed that the deletion encompassed at least 2,000 bp and an important gene (tentatively named LSG : LOH-supporter gene) was missing. Thus, when a LSG gene is damaged in the germline as a heterozygous state, then the LOH of the homologous area on the other chromosome is suppressed. The discovery of the new phenomenon for the mechanisms of the suppression of LOH is likely to be applied to various areas. Thus, when a tumor suppressing gene is damaged, a gene therapy destroying a nearby LSG on the same chromosome may successfully suppress the LOH of the other intact chromosome. Such a gene therapy may be useful to treat families with high incidence of cancers. Furthermore, the present type of gene changes may explain the mechanisms of low incidence of tumors in some families.

对腺嘌呤磷酸核糖基转移酶（APRT）位点体内体细胞突变的研究表明，人类体细胞的突变频率高得惊人。大多数突变为杂合性缺失（LOH）型。然而，在3个APRT缺失的杂合子中，没有观察到LOH，这表明该区域存在基因组印迹。然而，精确的分析表明，在这一区域没有观察到基因组印记，但这3人有一个独特的缺失突变，抑制了LOH的发生。采用选择性PCR和反相PCR技术，分析了种系突变抑制LOH现象。该突变基因（APRT^<**>del）从内含子4缺失，连接到未知基因上。重组位点序列测定发现缺失至少2000 bp，缺失一个重要基因（暂定名为LSG: loh -support gene）。因此，当一个LSG基因在种系中以杂合状态受损时，则另一条染色体上同源区域的LOH受到抑制。这一抑制LOH机理的新现象的发现有可能应用于各个领域。因此，当一个肿瘤抑制基因被破坏时，破坏同一染色体上附近的LSG的基因疗法可能成功地抑制另一个完整染色体的LOH。这种基因疗法可能对治疗癌症高发家族有用。此外，目前的基因变化类型可能解释肿瘤在一些家庭低发病率的机制。

项目成果

Hakoda M.et al.: "Similarity of in vivo somatic mutations at an autosomal adenine phosphoribosyltransferase locus between T and B cells in human periphera blood" Mutat.Res.357. 107-113 (1996)

Hakoda M.等人：“人外周血中 T 细胞和 B 细胞之间常染色体腺嘌呤磷酸核糖基转移酶位点体内体细胞突变的相似性”Mutat.Res.357。

Taniguchi A.et al: "Agermline mutation abolishing the original stop codon of human adenine phosphoribosyltransferase (APRT) gene leads to the complete loss of the enzyme protein" Submitted for publication.

Taniguchi A.等人：“Agermline突变废除了人腺嘌呤磷酸核糖基转移酶（APRT）基因的原始终止密码子导致酶蛋白完全丢失”已提交发表。

Hakoda M.et al: "Similarity of in vivo somatic mutations at an autosomal adenine phosphoribosyltransferase locus between T and B cells in human peripheral blood." Mutat.Res.357. 107-113 (1996)

Hakoda M.et al：“人外周血中 T 细胞和 B 细胞之间常染色体腺嘌呤磷酸核糖基转移酶位点体内体细胞突变的相似性。”

Hakoda M.et al: "Selection against blood cells deficient in hypoxanthine phosphoribosyltransferase(HPRT)in Lesch-Nyhan heterozygotes occarsat the level of multipotent stemce" Hum.Genet. 96. 674-680 (1995)

Hakoda M.等人：“在多能干细胞水平上对 Lesch-Nyhan 杂合子中次黄嘌呤磷酸核糖转移酶 (HPRT) 缺陷的血细胞进行选择”Hum.Genet。

Kamatani N.et al: "Origin of the most common mutation of adenine phosphoribosyltransferase among Japanese gces back to prehistoric era." Hum.Genet.98. 596-600 (1996)

Kamatani N.等人：“日本 gces 中最常见的腺嘌呤磷酸核糖转移酶突变的起源可追溯到史前时代。”