Correction of an enzyme trafficking defect in hereditary kidney stone disease in vitro
Correction of an enzyme trafficking defect in hereditary kidney stone disease in vitro
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DOI：
10.1042/bj20030371
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发表时间：
2003-08-15
影响因子：
4.1
通讯作者：
Danpure, CJ
中科院分区：
文献类型：
--
作者：
Lumb, MJ;Birdsey, GM;Danpure, CJ
在正常人肝细胞中，中间代谢酶丙氨酸：乙醛酸氨基转移酶（AGT）位于过氧化物酶体内。然而，在约。三分之一患有遗传性肾结石病的患者原发性高尿酸1型，AGT被误认为是线粒体。AGT的错误定位是由常见的P11 L（Pro（11）--> Leu）多态性和疾病特异性G170 R突变之间的协同相互作用引起的。多态性产生功能弱的线粒体靶向序列，其效率通过突变而增加。这两个取代在一起，但不是孤立的，抑制AGT二聚化，突出了过氧化物酶体和线粒体蛋白质输入机制的不同结构要求。在本研究中，我们表明，已知的非特异性增加蛋白质稳定性的处理（即，将温度从37 ℃降低到30 ℃或通过添加甘油）完全正常化转染COS细胞中表达的突变AGT的细胞内靶向。另一方面，已知降低蛋白质稳定性的治疗（例如将温度从37 ℃升高到42 ℃）加剧了靶向缺陷。这两种处理都不影响过氧化物酶体和线粒体蛋白质输入途径的相对效率。结果进行了讨论，根据已知的结构要求的两个蛋白质运输途径和制定可能的治疗策略原发性高尿酸1型。
In normal human hepatocytes, the intermediary-metabolic enzyme alanine:glyoxylate aminotransferase (AGT) is located within the peroxisomes. However, in approx. one-third of patients suffering from the hereditary kidney stone disease primary hyperoxaluria type 1, AGT is mistargeted to the mitochondria. AGT mistargeting results from the synergistic interaction between a common P11L (Pro(11) --> Leu) polymorphism and a disease-specific G170R mutation. The polymorphism generates a functionally weak mitochondria) targeting sequence, the efficiency of which is increased by the mutation. The two substitutions together, but not in isolation, inhibit AGT dimerization, highlighting the different structural requirements of the peroxisomal and mitochondrial protein-import machineries. In the present study, we show that treatments known to increase the stability of proteins non-specifically (i.e. lowering the temperature from 37 to 30 degreesC or by the addition of glycerol) completely normalize the intracellular targeting of mutant AGT expressed in transfected COS cells. On the other hand, treatments known to decrease protein stability (e.g. increasing the temperature from 37 to 42 degreesC) exacerbate the targeting defect. Neither of the treatments affects the relative efficiencies of the peroxisomal and mitochondria) protein-import pathways intrinsically. Results are discussed in the light of the known structural requirements of the two protein trafficking pathways and the formulation of possible treatment strategies for primary hyperoxaluria type 1.