Biallelic COLGALT1 variants are associated with cerebral small vessel disease
Biallelic COLGALT1 variants are associated with cerebral small vessel disease
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DOI：
10.1002/ana.25367
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发表时间：
2018-12-01
影响因子：
11.2
通讯作者：
Matsumoto, Naomichi
中科院分区：
文献类型：
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作者：
Miyatake, Satoko;Schneeberger, Sacha;Matsumoto, Naomichi
目的大约5%的脑部小血管疾病是遗传性的，其中包括COL4A1/COL4A2相关疾病。COL4A1/COL4A2编码脑血管基底膜的IV型胶原α1/2链。COL4A1/COL4A2突变损害了胶原向细胞外基质的分泌，从而导致血管脆性。COL4A1/COL4A2变异的诊断效率约为20%至30%，提示其他突变基因可能与该病相关。本研究旨在确定导致COL4A1/COL4A2相关疾病的新基因。方法对2个疑似COL4A1/COL4A2相关疾病的家系进行外显子全序列测定。我们通过构建三维结构模型，通过Western blotting和胶原半乳糖基转移酶检测胶原β(1-O)半乳糖基转移酶1(ColGalT1)的蛋白表达和活性，以及进行体外RNA干扰和挽救实验，验证了COLGALT1变异体的作用。结果外显子测序发现COLGALT1编码ColGalT1的双等位基因变异，参与IV型胶原翻译后修饰的2例患者：患者1的C.452T>；G(p.Leu151Arg)和c.1096delG(p.Glu366Argfs*15)，患者2的c.460G>；C(p.Ala154Pro)和c.1129G>；C(p.Gly377Arg)。三维模型分析表明，p.Leu151Arg和p.Ala154Pro破坏了蛋白质折叠的稳定性，使酶活性受损。患者1的ColGalT1蛋白表达和ColGalT活性均为阴性。RNA干扰研究表明，减少的ColGalT1改变了COL4A1的分泌，救援实验表明，与野生型相比，突变体COLGALT1不能充分恢复细胞中COL4A1的产生。双等位基因COLGALT1变异通过与COL4A1/COL4A2相关疾病的共同分子发病机制导致大脑小血管异常。
Objective Approximately 5% of cerebral small vessel diseases are hereditary, which include COL4A1/COL4A2-related disorders. COL4A1/COL4A2 encode type IV collagen alpha 1/2 chains in the basement membranes of cerebral vessels. COL4A1/COL4A2 mutations impair the secretion of collagen to the extracellular matrix, thereby resulting in vessel fragility. The diagnostic yield for COL4A1/COL4A2 variants is around 20 to 30%, suggesting other mutated genes might be associated with this disease. This study aimed to identify novel genes that cause COL4A1/COL4A2-related disorders. Methods Whole exome sequencing was performed in 2 families with suspected COL4A1/COL4A2-related disorders. We validated the role of COLGALT1 variants by constructing a 3-dimensional structural model, evaluating collagen beta (1-O) galactosyltransferase 1 (ColGalT1) protein expression and ColGalT activity by Western blotting and collagen galactosyltransferase assays, and performing in vitro RNA interference and rescue experiments. Results Exome sequencing demonstrated biallelic variants in COLGALT1 encoding ColGalT1, which was involved in the post-translational modification of type IV collagen in 2 unrelated patients: c.452 T > G (p.Leu151Arg) and c.1096delG (p.Glu366Argfs*15) in Patient 1, and c.460G > C (p.Ala154Pro) and c.1129G > C (p.Gly377Arg) in Patient 2. Three-dimensional model analysis suggested that p.Leu151Arg and p.Ala154Pro destabilized protein folding, which impaired enzymatic activity. ColGalT1 protein expression and ColGalT activity in Patient 1 were undetectable. RNA interference studies demonstrated that reduced ColGalT1 altered COL4A1 secretion, and rescue experiments showed that mutant COLGALT1 insufficiently restored COL4A1 production in cells compared with wild type. Interpretation Biallelic COLGALT1 variants cause cerebral small vessel abnormalities through a common molecular pathogenesis with COL4A1/COL4A2-related disorders.