Mutations in the intellectual disability gene KDM5C reduce protein stability and demethylase activity
Mutations in the intellectual disability gene KDM5C reduce protein stability and demethylase activity
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DOI：
10.1093/hmg/ddv046
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发表时间：
2015-05-15
影响因子：
3.5
通讯作者：
Shi, Yang
中科院分区：
文献类型：
--
作者：
Brookes, Emily;Laurent, Benoit;Shi, Yang
KDM5C突变是导致男性x连锁智力残疾的重要原因。KDM5C编码组蛋白去甲基化酶，表明染色质结构的改变可能导致疾病。我们使用原代患者细胞和生化方法来研究患者突变对KDM5C表达、稳定性和催化活性的影响。我们报道并描述了一种新的无义突变c.3223delG (p.V1075Yfs*2)，该突变导致KDM5C蛋白的丢失。我们还鉴定了两种KDM5C错义突变，c.1439C > T （p.P480L）和c.1204G > T (p.p d402y)，它们与蛋白质生产兼容，但损害了稳定性和酶活性。最后，我们证明了KDM5C翻译起始密码子的C . 2t > C突变导致翻译重新启动和产生n端截断蛋白（p.M1_E165del），该蛋白不稳定且缺乏可检测的去甲基化酶活性。患者成纤维细胞没有显示组蛋白甲基化的全局变化，但我们发现了几个上调的基因，表明染色质构象和基因表达的局部变化。这种对KDM5C患者突变的彻底检查表明，在评估智力残疾突变的功能结果时，从酶产生到催化活性等多个层面上检查患者突变的分子后果是有用的。
Mutations in KDM5C are an important cause of X-linked intellectual disability in males. KDM5C encodes a histone demethylase, suggesting that alterations in chromatin landscape may contribute to disease. We used primary patient cells and biochemical approaches to investigate the effects of patient mutations on KDM5C expression, stability and catalytic activity. We report and characterize a novel nonsense mutation, c.3223delG (p.V1075Yfs*2), which leads to loss of KDM5C protein. We also characterize two KDM5C missense mutations, c.1439C > T (p.P480L) and c.1204G > T (p.D402Y) that are compatible with protein production, but compromise stability and enzymatic activity. Finally, we demonstrate that a c.2T > C mutation in the translation initiation codon of KDM5C results in translation re-start and production of a N-terminally truncated protein (p.M1_E165del) that is unstable and lacks detectable demethylase activity. Patient fibroblasts do not show global changes in histone methylation but we identify several up-regulated genes, suggesting local changes in chromatin conformation and gene expression. This thorough examination of KDM5C patient mutations demonstrates the utility of examining the molecular consequences of patient mutations on several levels, ranging from enzyme production to catalytic activity, when assessing the functional outcomes of intellectual disability mutations.