title: Nephrogenic diabetes insipidus: functional analysis of new AVPR2 mutations identified in Italian families.
abstract: 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.
authors.affiliation: Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Albertazzi
authors.affiliation: Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
authors.forename: Deborah
authors.initials: D
authors.lastname: Zanchetta
authors.affiliation: Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
authors.forename: Pascaline
authors.initials: P
authors.lastname: Barbier
authors.affiliation: Consiglio Nazionale delle Ricerche Institute of Advanced Biomedical Technologies, Milan, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Faranda
authors.affiliation: Consiglio Nazionale delle Ricerche Institute of Advanced Biomedical Technologies, Milan, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Frattini
authors.affiliation: Consiglio Nazionale delle Ricerche Institute of Advanced Biomedical Technologies, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Vezzoni
authors.affiliation: II Paediatric Clinic, Milan, Italy.
authors.forename: Mirella
authors.initials: M
authors.lastname: Procaccio
authors.affiliation: II Paediatric Clinic, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Bettinelli
authors.affiliation: Department of Pharmacology, University of Milan, Milan, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Guzzi
authors.affiliation: Department of Pharmacology, University of Milan, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Parenti
authors.affiliation: Consiglio Nazionale delle Ricerche Cellular and Molecular Pharmacology Center, Milan, Italy.
authors.forename: Bice
authors.initials: B
authors.lastname: Chini
mesh_terms: 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
chemical_list: D017483:Receptors, Vasopressin; D000242:Cyclic AMP