Urinary content of aquaporin 1 and 2 in nephrogenic diabetes insipidus

Hereditary nephrogenic diabetes insipidus (NDI) is caused by mutations in either the X-chromosomal gene encoding the vasopressin V2-receptor or in the autosomal gene encoding aquaporin-2. Expressed in Xenopus oocytes, the AQP2 gene mutations found in NDl have been shown to reduce the stability of th...

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Bibliographic Details
Published in:Journal of the American Society of Nephrology 1996-06, Vol.7 (6), p.836-841
Main Authors: Deen, P M, van Aubel, R A, van Lieburg, A F, van Os, C H
Format: Article
Language:English
Subjects:
Adult
Aquaporin 1
Aquaporin 2
Aquaporin 6
Aquaporins
Blood Group Antigens
Child
Child, Preschool
Diabetes Insipidus, Nephrogenic - genetics
Diabetes Insipidus, Nephrogenic - urine
Diuresis
Female
Humans
Immunoblotting
Ion Channels - genetics
Ion Channels - urine
Male
Middle Aged
Mutation
Receptors, Vasopressin - genetics
Reference Values
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Summary:Hereditary nephrogenic diabetes insipidus (NDI) is caused by mutations in either the X-chromosomal gene encoding the vasopressin V2-receptor or in the autosomal gene encoding aquaporin-2. Expressed in Xenopus oocytes, the AQP2 gene mutations found in NDl have been shown to reduce the stability of the encoded protein. This study investigated the in vivo stability of mutant and wild-type aquaporin-2 proteins by measuring their excretion in urine of NDl patients and healthy individuals. On immunoblots, the urine samples from healthy volunteers revealed clear aquaporin-1 and aquaporin-2 signals in antidiuretic but not diuretic states. In the urine of a female patient, whose NDl is explained by low expression of the wild-type V2-receptor gene, aquaporin-2 excretion was high and comparable with that in a healthy individual during antidiuresis. In the urine of a male patient with a non-sense mutation in the V2-receptor gene, a weak aquaporin-2 signal was detected. In NDl patients with mutations in the aquaporin-2 gene, aquaporin-2 could not be detected in urine, suggesting a low stability of mutant aquaporin-2 proteins. In four out of seven NDl patients, aquaporin-1 excretion was relatively high, which suggests a compensatory increase in proximal reabsorption in NDl.
ISSN:1046-6673
1533-3450
DOI:10.1681/ASN.V76836