Gyrate Atrophy of The Choroid and Retina

1.线粒体酶的普遍缺陷。鸟氨酸转氨酶(OAT：EC 2.6.1.13)是回状萎缩症(GA)的标志，GA是一种导致失明的眼部脉络膜和视网膜的遗传性退行性疾病。以本实验室已构建并鉴定的人OAT基因和抗人OAT抗体为探针，检测GA患者的OAT基因、mRNA和蛋白。对14名GA患者的基因组DNA、RNA和蛋白质的印迹分析发现，1例OTA功能基因部分杂合性缺失，没有检测到燕麦mRNA，燕麦抗体反应蛋白水平几乎检测不到。其余病例燕麦蛋白基因、信使核糖核酸均正常，燕麦蛋白表达有不同程度的降低。然后，我们更准确地分析了另一个遗传算法的案例。Southern分析表明，该功能基因大体完整。Northern对他的燕麦mRNA的分析表明，燕麦信息只有正常水平的一半，表明e…燕麦基因的两个等位基因中只有一个有更多的表达。通过体外翻译和抗人OAT抗体免疫沉淀对表达的OAT mRNA进行功能分析表明，该消息合成了一种燕麦蛋白。表达的消息被克隆和测序，结果表明，在翻译的燕麦蛋白的第319位，含有从C到T的单一碱基改变，导致氨基酸密码子从CAT(组氨酸)改变为TAT(酪氨酸)。在体外线粒体转运/处理系统中对突变前体进行了测试。结果表明，来自回旋萎缩患者的突变型燕麦蛋白前体可以转运到线粒体，但在那里被最小限度地加工。我们用免疫细胞化学方法对人眼组织中的鸟氨酸转氨酶进行了定位。在视网膜中，神经节细胞和一些无长突细胞呈免疫反应。色素颗粒使虹膜、睫状体色素上皮、脉络膜和视网膜色素上皮中的免疫反应产物难以辨认。我们的发现表明，鸟氨酸转氨酶在这些眼组织中的鸟氨酸代谢中起着重要作用。较少

1. A generalized deficiency in the mitochondrial enzyme. Ornithine aminotransferase (OAT : EC 2.6.1.13), is the hallmark of gyrate atrophy (GA), a hereditary degenerative disease of the choroid and retina of the eye that leads to blindness. A human OAT cDNA, previously constructed and characterized in our laboratory, and anti-human OAT antibody were used as probes to examine the OAT gene, mRNA and protein of GA patients. A blot analysis of the genomic DNAs, RNAs, and proteins of 14 GA patients identified a case with a partial heterozygous deletion of the functional OTA gene, no detectable OAT mRNA, and a barely detectable level of OAT antibody-reactive protein. The rest of the cases showed grossly normal OAT gene, mRNA, and variably reduced levels of OAT protein.2. We then analyzed another case of GA more precisely. Southern analysis indicated the functional gene to be grossly intact. Northern analysis of his OAT mRNA demonstrated only half the normal level of OAT message, suggesting e … More xpression of only one of the two alleles of the OAT gene. A functional assay of the expressed OAT mRNA by in vitro translation and immunoprecipitation with antihuman OAT antibody indicated synthesis of an OAT protein from the message. The expressed message was cloned and sequenced and was shown to contain a single base change from C to T, resulting in an amino acid codon change from CAT (histidine) to TAT (tyrosine) at position 319 in the translated OAT protein. The mutant precursors were tested in an in vitro mitochondrial transport/ processing system. The results indicate that the mutant OAT precursor from the gyrate atrophy patient can be transported to the mitochondria but is minimally processed there.3. We localized ornithine aminotransferase in human ocular tissues using immunocytochemical procedures. In the retina, ganglion cells and some amacrine cells were immunoreactive. Pigmented granules made it difficult to identify immunoreactive products in the iris, pigmented epithelium of the ciliary body, choroid, and retinal pigment epithelium. Our findings suggested that ornithine aminotransferase plays an important role in ornithine metabolism in these ocular tissues. Less