title: Proximal tubule NHE3 activity is inhibited by beta-arrestin-biased angiotensin II type 1 receptor signaling.
abstract: Physiological concentrations of angiotensin II (ANG II) upregulate the activity of Na(+)/H(+) exchanger isoform 3 (NHE3) in the renal proximal tubule through activation of the ANG II type I (AT1) receptor/G protein-coupled signaling. This effect is key for maintenance of extracellular fluid volume homeostasis and blood pressure. Recent findings have shown that selective activation of the beta-arrestin-biased AT1 receptor signaling pathway induces diuresis and natriuresis independent of G protein-mediated signaling. This study tested the hypothesis that activation of this AT1 receptor/beta-arrestin signaling inhibits NHE3 activity in proximal tubule. To this end, we determined the effects of the compound TRV120023, which binds to the AT1R, blocks G-protein coupling, and stimulates beta-arrestin signaling on NHE3 function in vivo and in vitro. NHE3 activity was measured in both native proximal tubules, by stationary microperfusion, and in opossum proximal tubule (OKP) cells, by Na(+)-dependent intracellular pH recovery. We found that 10(-7) M TRV120023 remarkably inhibited proximal tubule NHE3 activity both in vivo and in vitro. Additionally, stimulation of NHE3 by ANG II was completely suppressed by TRV120023 both in vivo as well as in vitro. Inhibition of NHE3 activity by TRV120023 was associated with a decrease in NHE3 surface expression in OKP cells and with a redistribution from the body to the base of the microvilli in the rat proximal tubule. These findings indicate that biased signaling of the beta-arrestin pathway through the AT1 receptor inhibits NHE3 activity in the proximal tubule at least in part due to changes in NHE3 subcellular localization.
authors.affiliation: Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil;
authors.forename: Carla P
authors.initials: CP
authors.lastname: Carneiro de Morais
authors.affiliation: Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil;
authors.forename: Juliano Z
authors.initials: JZ
authors.lastname: Polidoro
authors.affiliation: Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California; and.
authors.forename: Donna L
authors.initials: DL
authors.lastname: Ralph
authors.affiliation: Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil;
authors.forename: Thaissa D
authors.initials: TD
authors.lastname: Pessoa
authors.affiliation: Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil;
authors.forename: Maria
authors.initials: M
authors.lastname: Oliveira-Souza
authors.affiliation: Department of Physiological Sciences, Federal University of Espírito Santo, Vitoria, Espírito Santo, Brazil.
authors.forename: Valério G
authors.initials: VG
authors.lastname: Barauna
authors.affiliation: Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil;
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Rebouças
authors.affiliation: Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil;
authors.forename: Gerhard
authors.initials: G
authors.lastname: Malnic
authors.affiliation: Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California; and.
authors.forename: Alicia A
authors.initials: AA
authors.lastname: McDonough
authors.affiliation: Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil; adriana.girardi@incor.usp.br.
authors.forename: Adriana C C
authors.initials: AC
authors.lastname: Girardi
mesh_terms: D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000502:physiology; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000502:physiology*; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D000071557:beta-Arrestins
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D019390:Arrestins; D009842:Oligopeptides; D044140:Receptor, Angiotensin, Type 1; C000613385:SLC9A3 protein, human; C000613387:Slc9a3 protein, rat; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D000071557:beta-Arrestins; C555535:sarcosine-arginyl-valyl-tyrosyl-lysyl-histidyl-prolyl-alanine; D012964:Sodium; C555534:Sar-Arg-Val-Tyr-Ile-His-Pro-Ala-OH
keywords: OKP cells; TRV120023; biased agonism; renal sodium transport