New VMD2 gene mutations identified in patients affected by Best vitelliform macular dystrophy
New VMD2 gene mutations identified in patients affected by Best vitelliform macular dystrophy
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DOI：
10.1136/jmg.2006.044511
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发表时间：
2007-03-01
影响因子：
4
通讯作者：
Abitbol, M.
中科院分区：
文献类型：
--
作者：
Marchant, D.;Yu, K.;Abitbol, M.
目的：在一个名为VMD 2的基因中发现了导致Best卵黄状黄斑营养不良（BVMD）的突变。VMD 2基因编码一种名为bestrophin-1（hBest 1）的跨膜蛋白，它是一种Ca 2+敏感的氯离子通道。本研究旨在确定27例BVMD患者的疾病特异性突变。由于这种疾病的特点是改变Cl-通道功能，膜片钳分析被用来测试的假设，VMD 2突变的变体之一，导致diseases.Methods：直接测序分析的11 VMD 2外显子进行检测新的异常序列。hBest 1的突变体在HEK-293细胞中表达，并用全细胞膜片钳分析检测相关的Cl-电流。其中一个突变（Q293 H）特别严重。表达Q293 H突变体的人胚肾细胞的膜片钳分析表明，该突变体通道是无功能的。此外，Q293 H突变体抑制野生型bestrophin-1通道的功能，在一个显性负性manners.Conclusions：这项研究提供了进一步的支持，VMD 2突变的想法是一个必要的因素最好的疾病。然而，由于在具有Q293 H突变的家族中观察到VMD 2的可变表达性，因此也清楚VMD 2中的疾病相关突变不足以产生BVMD。Q293 H突变体在膜中不形成功能性通道的发现可以通过通道电导或门控机制的破坏或通过蛋白质向质膜的不适当运输来解释。
Purpose: The mutations responsible for Best vitelliform macular dystrophy (BVMD) are found in a gene called VMD2. The VMD2 gene encodes a transmembrane protein named bestrophin-1 (hBest1) which is a Ca2+-sensitive chloride channel. This study was performed to identify disease-specific mutations in 27 patients with BVMD. Because this disease is characterised by an alteration in Cl- channel function, patch clamp analysis was used to test the hypothesis that one of the VMD2 mutated variants causes the disease.Methods: Direct sequencing analysis of the 11 VMD2 exons was performed to detect new abnormal sequences. The mutant of hBest1 was expressed in HEK-293 cells and the associated Cl- current was examined using whole-cell patch clamp analysis.Results: Six new VMD2 mutations were identified, located exclusively in exons four, six and eight. One of these mutations (Q293H) was particularly severe. Patch clamp analysis of human embryonic kidney cells expressing the Q293H mutant showed that this mutant channel is non-functional. Furthermore, the Q293H mutant inhibited the function of wild-type bestrophin-1 channels in a dominant negative manner.Conclusions: This study provides further support for the idea that mutations in VMD2 are a necessary factor for Best disease. However, because variable expressivity of VMD2 was observed in a family with the Q293H mutation, it is also clear that a disease-linked mutation in VMD2 is not sufficient to produce BVMD. The finding that the Q293H mutant does not form functional channels in the membrane could be explained either by disruption of channel conductance or gating mechanisms or by improper trafficking of the protein to the plasma membrane.