First identification of PODXL nonsense mutations in autosomal dominant focal segmental glomerulosclerosis
First identification of PODXL nonsense mutations in autosomal dominant focal segmental glomerulosclerosis
复制标题
首次鉴定常染色体显性局灶节段性肾小球硬化症中的 PODXL 无义突变
DOI：
10.1042/cs20180676
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发表时间：
2019-01-15
期刊：
影响因子：
6
通讯作者：
Ren, Hong-Qi
中科院分区：
文献类型：
--
作者：
Lin, Fu-Jun;Yao, Lei;Ren, Hong-Qi
最近，一种新的杂合错义突变c。在常染色体显性局灶节段性肾小球硬化症 (AD-FSGS) 家系中鉴定出编码足萼蛋白的 PODXL 基因中的 T1421G (p. L474R)。然而，这种 PODXL 突变似乎不会损害足萼蛋白功能，因此有必要鉴定新的 PODXL 突变并确定其对 FSGS 的致病作用。在本研究中，我们报道了通过全外显子组测序（WES）在一个以蛋白尿和肾功能不全为特征的AD遗传的中国家系中鉴定出杂合无义PODXL突变（c.C976T；p.Arg326X）。与健康对照和无 PODXL 突变的血液透析对照相比，两名接受血液透析的受影响患者的可用外周血细胞样本中总 mRNA 和 PODXL 蛋白丰度降低。我们通过 WES 在 AD-FSGS 的英国-印度系谱中发现了另一个新的 PODXL 杂合无义突变（c. C1133G；p. Ser378X）。体外研究表明，转染pEGFP-PODXL-Arg326X或pEGFP-PODXL-Ser378X质粒的人胚肾293T细胞的mRNA和PODXL蛋白表达量明显低于转染野生型质粒的细胞。阻断无义介导的 mRNA 衰减 (NMD) 可显着恢复突变 mRNA 和 PODXL 蛋白的数量，这表明 PODXL 无义突变的致病作用很可能是由于 NMD 导致的足萼蛋白缺乏。 siRNA 推断 PODXL 无义突变引起的功能后果导致 RhoA 和 ezrin 活性降低、细胞迁移和应力纤维形成。我们的结果提供了新的数据，表明杂合 PODXL 无义突变在 FSGS 的发展中。
Recently, a novel heterozygous missense mutation c. T1421G (p. L474R) in the PODXL gene encoding podocalyxin was identified in an autosomal dominant focal segmental glomerulosclerosis (AD-FSGS) pedigree. However, this PODXL mutation appeared not to impair podocalyxin function, and it is necessary to identify new PODXL mutations and determine their causative role for FSGS. In the present study, we report the identification of a heterozygous nonsense PODXL mutation (c. C976T; p. Arg326X) in a Chinese pedigree featured by proteinuria and renal insufficiency with AD inheritance by whole exome sequencing (WES). Total mRNA and PODXL protein abundance were decreased in available peripheral blood cell samples of two affected patients undergoing hemodialysis, compared with those in healthy controls and hemodialysis controls without PODXL mutation. We identified another novel PODXL heterozygous nonsense mutation (c. C1133G; p. Ser378X) in a British-Indian pedigree of AD-FSGS by WES. In vitro study showed that, human embryonic kidney 293T cells transfected with the pEGFP-PODXL-Arg326X or pEGFP-PODXL-Ser378X plasmid expressed significantly lower mRNA and PODXL protein compared with cells transfected with the wild-type plasmid. Blocking nonsense-mediated mRNA decay (NMD) significantly restored the amount of mutant mRNA and PODXL proteins, which indicated that the pathogenic effect of PODXL nonsense mutations is likely due to NMD, resulting in podocalyxin deficiency. Functional consequences caused by the PODXL nonsense mutations were inferred by siRNA resulted in decreased RhoA and ezrin activities, cell migration and stress fiber formation. Our results provided new data implicating heterozygous PODXL nonsense mutations in the development of FSGS.