Molecular basis of late onset ornithine transcarbamylase deficiency in male

男性迟发性鸟氨酸转氨甲酰酶缺乏症的分子基础

• 批准号: 08671192
• 负责人: NISHIYORI Atsushi
• 金额: $ 1.47万
• 依托单位: Kurume University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08671192/
• 关键词: ornithine transcarbamylase deficiency; late onset; expression analysis

We had reported a cluster of male ornithine transcarbamylase deficiency (OTC) patients with onset from late adolescence to the presenile period. In this study, we discovered three patients who have R4OH mutation. We detected R4OH mutation in liver specimens from one of the patients with RFLP, but in fibroblast and skin specimens the RFLP showed almost normal. This result indicated that the R4OH mutation in the patient may be somatic mutation. The R4OH mutation has been discovered in different ethnic groups. This mutation may arise as a result of a recurrent mutation because the mutation involves a CpG island.We have showed that posttranslational mechanisms related late onset omithine transcarbamylase deficiency patients bearing R4OH or Y55D mutations. In this study, expression analysis using Cos 1 cells indicated that the OTC activities of cells transfected with the plasmid only, and the plasmid containing wild type cDNA were 23.5 (nmol/min/ml) and 1955*140 (n=3) respectively. On the other hand OTC activities with R4OH mutant cDNA, and Y55D cDNA were 670*130 (n=3) and 627*124 (n=3) respectively. The activities of R4OH mutant OTC and Y55D mutant OTC, as normalized for beta-galactosidase activity were 28% and 26% of the normal OTC activity respectively. When the cell lysates were subjected to five cycles of freezing and thawing, the activities of the wild type OTC and Y55D mutant OTC did not change, whereas the activity of the R4OH mutant OTC decreased to 6% of wild type that before treatment. These results indicated that the R4OH mutant OTC was physically unstable and was degraded more rapidly than the wild type enzyme. Thus, the R4OH OTC activity may be depressed to an incompatible level once a metabolic burden that would facilitate inactivation and degradation of the mutant enzyme is applied.

我们报告了一组男性鸟氨酸转氨酶缺乏症(OTC)患者，其发病时间从青春期晚期到老年前期。在这项研究中，我们发现了三名患者存在R4OH突变。我们在其中一例RFLP患者的肝脏标本中检测到R4OH突变，但在成纤维细胞和皮肤标本中，RFLP显示几乎正常。提示该患者的R4OH突变可能是体细胞突变。在不同的种族中发现了R4OH突变。这种突变可能是一种反复突变的结果，因为该突变涉及一个CpG岛。我们已经证明，翻译后机制与携带R4OH或Y55D突变的迟发性欧米辛转氨酶缺乏症患者有关。用Cos-1细胞进行的表达分析表明，仅转染组和含有野生型cDNA组的OTC活性分别为23.5(nmol/min/ml)和1955×140(n=3)。R4OH突变体和Y55D的OTC活性分别为670×130(n=3)和627×124(n=3)。R4OH突变株OTC和Y55D突变株OTC的β-半乳糖苷酶活性分别为正常OTC活性的28%和26%。冻融5次后，野生型OTC和Y55D突变型OTC的活性没有变化，而R4OH突变体OTC的活性下降到处理前的6%。这些结果表明，R4OH突变体OTC在生理上是不稳定的，而且比野生型酶降解更快。因此，一旦施加了促进突变酶失活和降解的代谢负荷，R4OH OTC活性可能被抑制到不相容的水平。

项目成果

Atsushi Nishiyori: "Y55P mutation in Ornihine Transcorbonylase Associated With Late-Onset Hyperammonemia in a Mole." Hum Mutat. Supplerment1. S131-S133 (1998)

Atsushi Nishiyori：“鸟氨酸转胆固醇酶 Y55P 突变与鼹鼠迟发性高氨血症相关。”

Ichiro Matsuda: "Phenotypic variability in mole patients carring the mutant ornithine transcarbamylase (OTC) allele." J Med Genet. Vol33・NO.8. 645-648 (1996)

Ichiro Matsuda：“携带突变鸟氨酸转氨甲酰酶 (OTC) 等位基因的葡萄胎患者的表型变异。”J Med Genet 第 33 卷·NO.8 (1996)。

Yoriko Watanabe: "P1148A in fibrilin-1 is not a mutation leading to Shprinzen-Goldberg Syndrome." Hum Mutat. Vol.10. 326-327 (1997)

Yoriko Watanabe：“fibrilin-1 中的 P1148A 并不是导致 Shprinzen-Goldberg 综合征的突变。”

Atsushi Nishiyori: "Y55D Mutation in Ornithine Transcarbamylase Associated With Late-Onset Hyperammonemia in a Male" Human Mutation. Supplement 1. S131-S133 (1998)

Atsushi Nishiyori：“鸟氨酸转氨甲酰酶 Y55D 突变与男性迟发性高氨血症相关”人类突变。