Trimerization and Genotype-Phenotype Correlation of COL4A5 Mutants in Alport Syndrome
Trimerization and Genotype-Phenotype Correlation of COL4A5 Mutants in Alport Syndrome
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DOI：
10.1016/j.ekir.2020.01.008
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发表时间：
2020-05-01
影响因子：
6
通讯作者：
Kai, Hirofumi
中科院分区：
文献类型：
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作者：
Kamura, Misato;Yamamura, Tomohiko;Kai, Hirofumi
简介：Alport综合征是一种遗传性肾小球肾炎，由COL 4A 3、COL 4A 4或COL 4A 5基因突变引起的胶原蛋白α 345（IV）异源三聚体破坏引起。许多临床研究已经阐明了基因型与表型之间的相关性，但仍存在许多模糊和不足。在这里，我们专注于α 345（IV）异源三聚体的α 5（IV）错义突变体作为一种新的因素，以进一步了解Alport syndrome.Methods的病理生理学：我们选择了9 α 5（IV）错义突变体与典型的甘氨酸取代，临床上不同的疾病进展。为了量化每个突变体的三聚体，分裂nanoluciferase融合的α 3/α 5突变体和α 4转染到细胞中，和细胞内和分泌的异源三聚体检测发光使用的测定，我们开发previous.Results：三聚体的形成和分泌模式往往是类似的野生型在大多数的突变，不显示蛋白尿在年轻的时候。另一方面，在所有显示蛋白尿和早期肾衰竭发作的突变中，三聚体分泌显著减少。其中一株突变体的胞内三聚体形成能力较低，其余突变体的胞内三聚体分泌能力较低。结论：α 345（IV）异源三聚体形成试验结果与临床基因型-表型密切相关。这些三聚体评估提供了额外的表型考虑，并可能有助于区分致病性和非致病性突变。
Introduction: Alport syndrome is a hereditary glomerulonephritis that results from the disruption of collagen alpha 345(IV) heterotrimerization caused by mutation in COL4A3, COL4A4 or COL4A5 genes. Many clinical studies have elucidated the correlation between genotype and phenotype, but there is still much ambiguity and insufficiency. Here, we focused on the alpha 345(IV) heterotrimerization of alpha 5(IV) missense mutant as a novel factor to further understand the pathophysiology of Alport syndrome.Methods: We selected 9 alpha 5(IV) missense mutants with typical glycine substitutions that clinically differed in disease progression. To quantify the trimerization of each mutant, split nanoluciferase-fused alpha 3/alpha 5 mutants and alpha 4 were transfected into the cells, and intracellular and secreted heterotrimer were detected by luminescence using an assay that we developed previously.Results: Trimer formation and secretion patterns tended to be similar to the wild type in most of the mutations that did not show proteinuria at a young age. On the other hand, trimer secretion was significantly reduced in all the mutations that showed proteinuria and early onset of renal failure. One of these mutants has low ability of intracellular trimer formation, and the others had the defect of low-level secretion. In addition, the mutant that is assumed to be nonpathogenic has similar trimer formation and secretion pattern as wild-type alpha 5(IV).Conclusion: The result of cell-based alpha 345(IV) heterotrimer formation assay was largely correlated with clinical genotype-phenotype. These trimerization assessments provide additional phenotypic considerations and may help to distinguish between pathogenic and nonpathogenic mutations.