title: Integrin signaling modulates AQP2 trafficking via Arg-Gly-Asp (RGD) motif.
abstract: Aquaporin-2 (AQP2) increases the water permeability of renal collecting ducts in response to vasopressin. Vasopressin stimulation is accompanied by a profound remodeling of actin cytoskeleton whose dynamics are regulated by crosstalk between intracellular and extracellular signals. Here, we report that AQP2 contains a conserved RGD domain in its external C-loop. Co-immunoprecipitation experiments demonstrated that AQP2 binds integrin β1 in renal tissue and in MCD4 cells. To investigate the role of this interaction on AQP2 trafficking, cells were exposed to synthetic RGD-containing peptides, GRGDNP or GRGDSP, able to bind certain integrins. Incubation with these peptides increased the membrane expression of AQP2 in the absence of hormonal stimulation as assessed by confocal analysis and cell surface biotinylation. To identify the signals underlying the effects of peptides on AQP2 trafficking, some possible intracellular messengers were evaluated. Exposure of MCD4 cells to GRGDNP increased intracellular cAMP as assessed by FRET studies while GRGDSP increased intracellular calcium concentration. Taken together, these data propose integrins as new players controlling the cellular localization of AQP2, via two distinct signal transduction pathways dependent on cAMP and calcium respectively.
authors.affiliation: Department of General and Environmental Physiology, University of Bari, Via Amendola 165/A, 70125 Bari, Italy. g.tamma@biologia.uniba.it
authors.forename: Grazia
authors.initials: G
authors.lastname: Tamma
authors.forename: Domenica
authors.initials: D
authors.lastname: Lasorsa
authors.forename: Marianna
authors.initials: M
authors.lastname: Ranieri
authors.forename: Lisa
authors.initials: L
authors.lastname: Mastrofrancesco
authors.forename: Giovanna
authors.initials: G
authors.lastname: Valenti
authors.forename: Maria
authors.initials: M
authors.lastname: Svelto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051399:Aquaporin 2 / Q000378:metabolism*; D002460:Cell Line; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: D051399:Aquaporin 2; D016023:Integrins; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid