Department of Endocrinology, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China.
Department of Ophthalmology, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China.
J Endocrinol Invest. 2021 Mar;44(3):471-480. doi: 10.1007/s40618-020-01329-y. Epub 2020 Jul 8.
Gitelman syndrome (GS) is an autosomal recessive renal tubular disease that arises as a consequence of mutations in the SLC12A3 gene, which codes for an Na-Cl cotransporter (NCC) in distal renal tubules. This study was designed to explore the mutations associated with GS in an effort to more fully understand the molecular mechanisms governing GS.
We analyzed SLC12A3 mutations in a pedigree including a 42-year-old male with GS as well as four related family members over three generations using Sanger and next generation sequencing approaches. We additionally explored the functional ramifications of identified mutations using both Xenopus oocytes and the HEK293T cell line.
We found that the subject with GS exhibited characteristic symptoms including sporadic thirst, fatigue, excess urination, and substantial hypokalemia and hypocalciuria, although magnesium levels were normal. Other analyzed subjects in this pedigree had normal laboratory findings and did not exhibit clear signs of GS. Sequencing analyses revealed that the GS subject exhibited a homozygous missense mutation (c.2874C > G, p.N958K) in exon 24 of SLC12A3. Both parents of this GS subject, as well as his older brother and daughter all exhibited heterozygous mutations at this same site. Functional analyses in Xenopus oocytes indicated that this mutated SLC12A3 gene encodes a protein which fails to mediate normal sodium transport, and when this mutant gene was expressed in HEK293T cells, we observed significant increases in endoplasmic reticulum (ER)-stress pathway activation.
The p.N958K mutation in exon 24 of SLC12A3 can trigger GS at least in part via enhancing ER stress responses.
吉特曼综合征（GS）是一种常染色体隐性肾小管疾病，是由于 SLC12A3 基因突变引起的，该基因编码位于远端肾小管的 Na-Cl 共转运体（NCC）。本研究旨在探讨与 GS 相关的突变，以期更全面地了解 GS 的分子机制。
我们使用 Sanger 和下一代测序方法分析了一个包括一名 42 岁男性 GS 患者在内的家系中的 SLC12A3 基因突变，该患者及其三代共四名相关家族成员参与了研究。我们还使用非洲爪蟾卵母细胞和 HEK293T 细胞系探索了鉴定出的突变的功能后果。
我们发现 GS 患者表现出特征性症状，包括偶发性口渴、疲劳、多尿和严重低钾血症和低钙尿症，尽管镁水平正常。该家系中其他被分析的患者实验室检查结果正常，没有明显的 GS 迹象。序列分析显示，GS 患者在 SLC12A3 的外显子 24 中表现出纯合错义突变（c.2874C > G，p.N958K）。该 GS 患者的父母以及他的哥哥和女儿均在该位点表现出杂合突变。非洲爪蟾卵母细胞中的功能分析表明，这种突变的 SLC12A3 基因编码一种不能介导正常钠转运的蛋白质，当这种突变基因在 HEK293T 细胞中表达时，我们观察到内质网（ER）应激途径的激活显著增加。
SLC12A3 外显子 24 中的 p.N958K 突变至少部分通过增强 ER 应激反应引发 GS。
