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MOLECULAR GENETICS OF HUMAN LEFT-RIGHT AXIS MALFORMATIONS

人类左右轴畸形的分子遗传学

基本信息

批准号：
11670785
负责人：
KOSAKI Kenjiro
金额：
$ 2.24万
依托单位：
KEIO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

1) In the inv/inv mouse strain, integration of the tyrosinase minigene causes complete mirror image reversal of internal organs. Analysis of the transgenic integration site revealed that loss of function mutation of a novel gene, Inversin, is responsible for the disruption of normal left-right polarity. Based on these results, we hypothesized that mutations in the Inversin gene are associated with some cases of left-right axis malformations in humans. We cloned of the human INVERSIN cDNA, characterized its genomic structure, and screened for mutations among 112 sporadic and 14 familial cases of left-right axis malformations. We demonstrated that human INVERSIN, localizes to chromosome 9q3l, and encodes a protein with 9O% homology to the mouse homologue. Mutation analysis revealed 2 unique nucleotide substitutions, S371G and A650P which result in missense mutations. We conclude from the current study that INVERSIN mutations are rarely associated with human left-right axis malformations.2) Bioinformatic analyses of the human/mouse genome sequences of the flanking the lefty gene region revealed that mouse Lefty 1 is the ortholog of human LEFTY2 (also known as LEFTYB). Right sided silencer element of the mouse Lefty 1 is conserved in humans as well. Mutation analysis of more than one hundred patients with situs abnormalities, however, did not reveal any patients with LEFTY2 coding mutations.3) Left-right axis malformations is commonly observed in the F1 offspring of NOD (non-obese diabetic) mouse dams and sires from ICR strains. The ICR strain had 1) a 0.2 kb insertion in the putative promoter region of the isoform E of Hnf3beta together with a G to A change that could create a potential splice acceptor in the exon 3 of Hnf3beta (gene frequency 0.36), 2) five single base substitutions within the 5' controlling element and a proline to serine substitution (P2S) of Lefty1 (0.77). These substitutions may contribute to increased susceptibility to maternal diabetes.

1)在inv/inv小鼠品系中，酪氨酸酶minigene的整合导致内脏器官的完全镜像逆转。对转基因整合位点的分析表明，一种新基因Inversin的功能突变丧失是导致正常左右极性破坏的原因。基于这些结果，我们假设Inversin基因的突变与人类左右轴畸形的一些病例有关。我们克隆了人类INVERSIN cDNA，分析了其基因组结构，并对112例散发性和14例家族性左右轴畸形进行了突变筛选。我们证明了人类的INVERSIN，定位于染色体9q31，并编码一个与小鼠同源物90%同源的蛋白。突变分析发现2个独特的核苷酸替换，S371G和A650P导致错义突变。我们从目前的研究中得出结论，INVERSIN突变很少与人类左右轴畸形相关。2)生物信息学分析表明，小鼠lefty 1与人类LEFTY2（也称为LEFTYB）具有同源性。小鼠Lefty 1的右侧消音元件在人类中也是保守的。然而，对100多例位置异常患者的突变分析未发现任何LEFTY2编码突变患者。3)左右轴畸形常见于NOD（非肥胖糖尿病）小鼠的F1后代和ICR品系的后代。ICR菌株1)在Hnf3beta亚型E的假设启动子区域插入0.2 kb，并在Hnf3beta的第3外显子上发生G到a的变化，可能产生一个潜在的剪接受体（基因频率0.36），2)在5'控制元件内发生5个单碱基替换，Lefty1的脯氨酸到丝氨酸替换（P2S）（0.77）。这些替代可能会增加产妇患糖尿病的易感性。