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Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus

The aquaporin 2 (AQP2) plays a critical role in water reabsorption to maintain water homeostasis. AQP2 mutation leads to nephrogenic diabetes insipidus (NDI), characterized by polyuria, polydipsia, and hypernatremia. We previously reported that a novel AQP2 mutation (G215S) caused NDI in a boy. In t...

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Autores principales: Li, Qian, Lu, Bichao, Yang, Jia, Li, Chao, Li, Yanchun, Chen, Hui, Li, Naishi, Duan, Lian, Gu, Feng, Zhang, Jianmin, Xia, Weibo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8429928/
https://www.ncbi.nlm.nih.gov/pubmed/34512542
http://dx.doi.org/10.3389/fendo.2021.665145
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author Li, Qian
Lu, Bichao
Yang, Jia
Li, Chao
Li, Yanchun
Chen, Hui
Li, Naishi
Duan, Lian
Gu, Feng
Zhang, Jianmin
Xia, Weibo
author_facet Li, Qian
Lu, Bichao
Yang, Jia
Li, Chao
Li, Yanchun
Chen, Hui
Li, Naishi
Duan, Lian
Gu, Feng
Zhang, Jianmin
Xia, Weibo
author_sort Li, Qian
collection PubMed
description The aquaporin 2 (AQP2) plays a critical role in water reabsorption to maintain water homeostasis. AQP2 mutation leads to nephrogenic diabetes insipidus (NDI), characterized by polyuria, polydipsia, and hypernatremia. We previously reported that a novel AQP2 mutation (G215S) caused NDI in a boy. In this study, we aimed to elucidate the cell biological consequences of this mutation on AQP2 function and clarify the molecular pathogenic mechanism for NDI in this patient. First, we analyzed AQP2 expression in Madin-Darby canine kidney (MDCK) cells by AQP2-G215S or AQP2-WT plasmid transfection and found significantly decreased AQP2-G215S expression in cytoplasmic membrane compared with AQP2-WT, independent of forskolin treatment. Further, we found co-localization of endoplasmic reticulum (ER) marker (Calnexin) with AQP2-G215S rather than AQP2-WT in MDCK cells by immunocytochemistry. The functional analysis showed that MDCK cells transfected with AQP2-G215S displayed reduced water permeability compared with AQP2-WT. Visualization of AQP2 structure implied that AQP2-G215S mutation might interrupt the folding of the sixth transmembrane α-helix and/or the packing of α-helices, resulting in the misfolding of monomer and further impaired formation of tetramer. Taken together, these findings suggested that AQP2-G215S was misfolded and retained in the ER and could not be translocated to the apical membrane to function as a water channel, which revealed the molecular pathogenic mechanism of AQP2-G215S mutation and explained for the phenotype of NDI in this patient.
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spelling pubmed-84299282021-09-11 Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus Li, Qian Lu, Bichao Yang, Jia Li, Chao Li, Yanchun Chen, Hui Li, Naishi Duan, Lian Gu, Feng Zhang, Jianmin Xia, Weibo Front Endocrinol (Lausanne) Endocrinology The aquaporin 2 (AQP2) plays a critical role in water reabsorption to maintain water homeostasis. AQP2 mutation leads to nephrogenic diabetes insipidus (NDI), characterized by polyuria, polydipsia, and hypernatremia. We previously reported that a novel AQP2 mutation (G215S) caused NDI in a boy. In this study, we aimed to elucidate the cell biological consequences of this mutation on AQP2 function and clarify the molecular pathogenic mechanism for NDI in this patient. First, we analyzed AQP2 expression in Madin-Darby canine kidney (MDCK) cells by AQP2-G215S or AQP2-WT plasmid transfection and found significantly decreased AQP2-G215S expression in cytoplasmic membrane compared with AQP2-WT, independent of forskolin treatment. Further, we found co-localization of endoplasmic reticulum (ER) marker (Calnexin) with AQP2-G215S rather than AQP2-WT in MDCK cells by immunocytochemistry. The functional analysis showed that MDCK cells transfected with AQP2-G215S displayed reduced water permeability compared with AQP2-WT. Visualization of AQP2 structure implied that AQP2-G215S mutation might interrupt the folding of the sixth transmembrane α-helix and/or the packing of α-helices, resulting in the misfolding of monomer and further impaired formation of tetramer. Taken together, these findings suggested that AQP2-G215S was misfolded and retained in the ER and could not be translocated to the apical membrane to function as a water channel, which revealed the molecular pathogenic mechanism of AQP2-G215S mutation and explained for the phenotype of NDI in this patient. Frontiers Media S.A. 2021-08-27 /pmc/articles/PMC8429928/ /pubmed/34512542 http://dx.doi.org/10.3389/fendo.2021.665145 Text en Copyright © 2021 Li, Lu, Yang, Li, Li, Chen, Li, Duan, Gu, Zhang and Xia https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Endocrinology
Li, Qian
Lu, Bichao
Yang, Jia
Li, Chao
Li, Yanchun
Chen, Hui
Li, Naishi
Duan, Lian
Gu, Feng
Zhang, Jianmin
Xia, Weibo
Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus
title Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus
title_full Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus
title_fullStr Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus
title_full_unstemmed Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus
title_short Molecular Characterization of an Aquaporin−2 Mutation Causing Nephrogenic Diabetes Insipidus
title_sort molecular characterization of an aquaporin−2 mutation causing nephrogenic diabetes insipidus
topic Endocrinology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8429928/
https://www.ncbi.nlm.nih.gov/pubmed/34512542
http://dx.doi.org/10.3389/fendo.2021.665145
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