THE MAGNITUDE OF Ca2+ INDUCED Ca2+ RELEASE TRIGGERED BY ACTIVATION OF TRPV4 IS DEPENDENT ON THE EXPRESSION OF AQP2 IN RENAL CELLS

CAPURRO, CLAUDIA; LÓPEZ GONZÁLEZ, MACARENA; FORD PAULA; DI GIUSTO, GISELA; RIVAROLA, VALERIA; ALEJANDRO PIZZONI

Congreso; Reunión Conjunta de Sociedades de Biociencias 2017.; 2017

There is increasing evidence indicating that aquaporins (AQPs) may influence cell signaling by affecting TRPV4, a non-selective Ca2+ channel. In a previous communication we described that under TRPV4 stimulation, AQP2 can modulate SK3 (a KCa subtype) leading to hyperpolarization of the membrane potential. Surprisingly, TRPV4-mediated Ca2+ signals were not apparently affected by Vm hyperpolarization. Since other works reported that TRPV4 activation triggers Ca2+ induced Ca2+ release (CICR) from intracellular stores, the aim of the present work was to investigate if CICR can mask the influence of hyperpolarization on TRPV4-mediated Ca2+ influx in AQP2 expressing cells. Using fluorescent probe techniques, we studied intracellular Ca2+ concentration ([Ca2+]i) in response to activation of TRPV4 (with 4-PDD, 10 µM) in two renal cell lines expressing (AQP2-RCCD1) or not AQP2 (WT-RCCD1). In addition, we assessed the colocalization between SK3 and AQP2. We found that in both cell lines, TRPV4-mediated [Ca2+]i signals were unaffected by preincubation with dantrolene (10 µM), an inhibitor of Ca2+ release from ryanodine receptors. However, caffeine (5 mM), an inhibitor of Ca2+ release from inositol trisphosphate receptors (InsP3R), significantly diminished the response in both cell lines (Area under curve: Wt-Ctrl: 928±77, n=320 vs. Wt-Caf: 478±54, n=107, p