MLYCD mutation analysis: Evidence for protein mistargeting as a cause of MLYCD deficiency
MLYCD mutation analysis: Evidence for protein mistargeting as a cause of MLYCD deficiency
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DOI：
10.1002/humu.10264
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发表时间：
2003-10-01
期刊：
影响因子：
3.9
通讯作者：
FitzPatrick, DR
中科院分区：
文献类型：
--
作者：
Wightman, PJ;Santer, R;FitzPatrick, DR
丙二酰辅酶A脱羧酶（MLYCD）缺乏症是一种常染色体隐性遗传疾病，其特征为丙二酸尿、发育迟缓、癫痫发作、低血糖和心肌病。对 9 名无关患者的 MLYCD 基因组测序鉴定出 18 个致病等位基因中的 16 个，这些等位基因记录在新创建的人类 MLYCD 等位基因变异数据库 (http://mlycd.hgu.mrc.ac.uk/) 中。成纤维细胞系来自其中 8 名患者和两名先前报道的具有纯合 MLYCD 突变的患者。使用 C 端肽抗血清进行蛋白质印迹分析，检测到 66 kDa 条带，该条带在 6 名患者中不存在，在 3 名患者中大幅减少。一名患者的蛋白质水平有所增加，并伴有明显的 68-183-kDa 涂片带。表达 MLYCD 的患者细胞系的免疫细胞化学分析显示明显的细胞内错误定位。极端的 N 端突变 c.8G > A (p.G3D) 错误定位到质膜，表明新的靶向信号可能存在于四个氨基酸保守的 N 端基序中。假定的线粒体和过氧化物酶体起始密码子（M1 和 M40）之间的 25 个碱基缺失以及消除第二个密码子的点突变（c.119T > C，p-M40T）均显示出点状核周染色。由于预计这三种错误定位突变都不会改变肽的催化功能，因此 MLYCD 的正确亚细胞定位对其正常发挥作用似乎至关重要。 (C) 2003 Wiley-Liss, Inc.
Malonyl-CoA decarboxylase (MLYCD) deficiency is an autosomal recessive disorder characterized by malonic aciduria, developmental delay, seizure disorder, hypoglycemia, and cardiomyopathy. Genomic sequencing of MLYCD in nine unrelated patients identified 16 of 18 pathogenic alleles, which are documented in the newly created Human MLYCD Allelic Variant Database (http://mlycd.hgu.mrc.ac.uk/). Fibroblast cell lines were available from eight of these patients and two previously reported patients with homozygous MLYCD mutations. Western blot analysis using antisera raised to a C-terminal peptide detected a 66-kDa band that was absent in six patients and substantially reduced in three patients. One patient showed an increase in protein levels with a prominent smeary 68-183-kDa band. Immunocytochernical analysis of MLYCD,expressing patient cell lines showed apparent intracellular mislocalization. An extreme N-terminal mutation c.8G > A (p.G3D) mislocalized to the plasma membrane, suggesting that a novel targeting signal may reside in a four-amino acid conserved N-terminal motif. A 25-base deletion between the putative mitochondrial and peroxisomal initiating codons (M1 and M40) and a point mutation ablating the second of these (c.119T > C, p-M40T) both showed punctate perinuclear staining. As none of the three mislocalizing mutations are predicted to alter the catalytic function of the peptide, it seems likely that correct subcellular localization of MLYCD is critical for it to function normally. (C) 2003 Wiley-Liss, Inc.