Nephrogenic diabetes insipidus: functional analysis of new AVPR2 mutations identified in Italian families.
The aim of this study was to identify loss-of-function mutations of the V2 vasopressin receptor gene (AVPR2) in Italian patients affected by X-linked nephrogenic diabetes insipidus (NDI). Mutations were found in 15 of the 18 unrelated families investigated: nine of these mutations were previously unknown, including two affecting residues located in regions known to be important for determining the pharmacologic properties of the receptor, which were therefore functionally investigated. The first (A84D) involves a residue located near an aspartic acid (D85) that is highly conserved in all G protein-coupled receptors and that is believed to play a role in the process of their isomerization into functionally active and inactive states. The present study indicates that this mutation not only affects receptor folding in such a way as to lead to its retention inside the intracellular compartments but, as expected, also has profound effects on its binding and coupling properties. The second was a mutation of a tryptophan located at the beginning of the first extracellular loop (W99R) that greatly impaired the binding properties of the receptor and had a minor effect on its intracellular routing. Molecular analysis of the first extracellular loop bearing this mutation suggests that this residue plays a fundamental role in stabilizing the peptide/receptor interactions responsible for the high-affinity binding of agonists to the V2 receptor.
Albertazzi
Elena
E
Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
Zanchetta
Deborah
D
Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
Barbier
Pascaline
P
Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
Faranda
Sara
S
Consiglio Nazionale delle Ricerche Institute of Advanced Biomedical Technologies, Milan, Italy.
Frattini
Annalisa
A
Consiglio Nazionale delle Ricerche Institute of Advanced Biomedical Technologies, Milan, Italy.
Vezzoni
Paolo
P
Consiglio Nazionale delle Ricerche Institute of Advanced Biomedical Technologies, Milan, Italy.
Procaccio
Mirella
M
II Paediatric Clinic, Milan, Italy.
Bettinelli
Alberto
A
II Paediatric Clinic, Milan, Italy.
Guzzi
Francesca
F
Department of Pharmacology, University of Milan, Milan, Italy.
Parenti
Marco
M
Department of Pharmacology, University of Milan, Milan, Italy.
Chini
Bice
B
Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D015153:Blotting, Western; D002648:Child; D002675:Child, Preschool; D000242:Cyclic AMP / Q000378:metabolism; D018500:Diabetes Insipidus, Nephrogenic / Q000235:genetics* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D008040:Genetic Linkage; D006801:Humans; D007223:Infant; D007558:Italy / Q000453:epidemiology; D008297:Male; D020125:Mutation, Missense; D016133:Polymerase Chain Reaction; D017483:Receptors, Vasopressin / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D014960:X Chromosome
D017483:Receptors, Vasopressin; D000242:Cyclic AMP