Heteroligomerization of an Aquaporin-2 mutant with wild-type Aquaporin-2 and their misrouting to late endosomes/lysosomes explains dominant nephrogenic diabetes insipidus.
نویسندگان
چکیده
Autosomal nephrogenic diabetes insipidus (NDI), a disease in which the kidney is unable to concentrate urine in response to vasopressin, is caused by mutations in the Aquaporin-2 (AQP2) gene. Analysis of a new family with dominant NDI revealed a single nucleotide deletion (727deltaG) in one AQP2 allele, which encoded an AQP2 mutant with an altered and extended C-terminal tail. When expressed in oocytes, the tetrameric AQP2-727deltaG was retained within the cell. When co-expressed, AQP2-727deltaG, but not a mutant in recessive NDI (AQP2-R187C), formed hetero-oligomers with wild-type (wt) AQP2 and reduced the water permeability of these oocytes, because of a reduced plasma membrane expression of wt-AQP2. Expressed in renal epithelial cells, AQP2-727deltaG predominantly localized to the basolateral membrane and late endosomes/lysosomes, whereas wt-AQP2 was expressed in the apical membrane. Upon co-expressing in these cells, wt-AQP2 and AQP2-727deltaG mainly co-localized to late endosomes/lysosomes. In conclusion, hetero-oligomerization of AQP2-727deltaG with wt-AQP2 and consequent mistargeting of this complex to late endosomes/lysosomes results in absence of AQP2 in the apical membrane, which can explain dominant NDI in this family. Together with other mutants in dominant NDI, our data reveal that a misrouting, instead of a lack of function, is a general mechanism for the 'loss of function' phenotype in dominant NDI and visualizes for the first time a mislocalization of a wild-type protein to late endosomes/lysosomes in polarized cells after oligomerization with a mutant protein.
منابع مشابه
Defective processing and trafficking of water channels in nephrogenic diabetes insipidus.
Nephrogenic diabetes insipidus (NDI) is a disease characterized by the inability of the kidney to concentrate urine upon stimulation with vasopressin. Mutations in the gene for aquaporin-2 (AQP2) are the cause of the autosomal recessive and autosomal dominant forms of NDI. Mutant AQP2 proteins, found in autosomal recessive NDI, were shown to be misfolded and retarded in the endoplasmic reticulu...
متن کاملAn impaired routing of wild-type aquaporin-2 after tetramerization with an aquaporin-2 mutant explains dominant nephrogenic diabetes insipidus.
Autosomal recessive and dominant nephrogenic diabetes insipidus (NDI), a disease in which the kidney is unable to concentrate urine in response to vasopressin, are caused by mutations in the aquaporin-2 (AQP2) gene. Missense AQP2 proteins in recessive NDI have been shown to be retarded in the endoplasmic reticulum, whereas AQP2-E258K, an AQP2 mutant in dominant NDI, was retained in the Golgi co...
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Frame-shift mutations within the C terminus of aquaporin 2 (AQP2) cause autosomal-dominant nephrogenic diabetes insipidus (AD-NDI). To identify the molecular mechanism(s) of this disease in vivo and to test possible therapeutic strategies, we generated a mutant AQP2 (763-772 del) knockin mouse. Heterozygous knockin mice showed a severely impaired urine-concentrating ability. However, they were ...
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ورودعنوان ژورنال:
- Human molecular genetics
دوره 11 7 شماره
صفحات -
تاریخ انتشار 2002