Observing the dynamics of luminal and cytosolic calcium during IP3R-mediated calcium signals

LUCÍA FERNANDA LOPEZ; LORENA SIGAUT; SILVINA PONCE DAWSON

Congreso; 58th Biophysical Society Annual Meeting; 2014

Ca2+ signaling is ubiquitous across cell types. Ca2+ liberation through inositol 1,4,5-trisphosphate receptors (IP3R's) is a key component of the Ca2+ signaling toolkit.The role of cytosolic Ca2+ on the kinetics of IP3R?s and on the dynamics of theevoked signals has been studied at large both experimentally and by modeling. Therole of luminal Ca2+ has not been investigated with that much detail although it hasbeen found that it is relevant for signal termination in the case of Ca2+ releasethrough Ryanodine Receptors. In this work we present the results of observing thedynamics of luminal and cytosolic Ca2+ simultaneously in Xenopus laevis oocytesusing two dyes that have their peaks of emission at different wavelengths. Througha continuous photorelease of caged IP3 we are able to evoke a series of global andlocalized signals in this system. The analysis of such signals allows acharacterization of the extent to which distant regions can be coupled via thedynamics of luminal Ca2+. In this way we expect to advance into answering whetherluminal Ca2+ can generate the global feedback mechanism that is necessary toexplain the robustness of IP3R-mediated Ca2+ spikes as a signaling tool in spite ofthe inter-spike interval randomness.