Changes in Ca2+ Removal Can Mask the Effects of Geometry During IP3R Mediated Ca2+ Signals

PIEGARI, ESTEFANÍA; VILLARRUEL, CECILIA; PONCE DAWSON, SILVINA

Frontiers in Physiology

Frontiers

Año: 2019 vol. 10

Calcium (Ca2+) signals are ubiquitous. Most intracellular Ca2+ signals involve the releaseof Ca2+ from the endoplasmic reticulum (ER) through Inositol 1,4,5-TrisphosphateReceptors (IP3Rs). The non-uniform spatial organization of IP3Rs and the fact thattheir individual openings are coupled via cytosolic Ca2+ are key factors for thevariety of spatio-temporal distributions of the cytosolic [Ca2+] and the versatility ofthe signals. In this paper we combine experiments performed in untreated and inprogesterone-treated Xenopus laevis oocytes and mathematical models to investigatehow the interplay between geometry (the IP3R spatial distribution) and dynamics (theprocesses that characterize the release, transport, and removal of cytosolic Ca2+) affectsthe resulting signals. Signal propagation looks more continuous and spatially uniform intreated (mature) than in untreated (immature) oocytes. This could be due to the differentunderlying IP3R spatial distribution that has been observed in both cell types. The models,however, show that the rate of cytosolic Ca2+ removal, which is also different in both celltypes, plays a key role affecting the coupling between Ca2+ release sites in such a waythat the effect of the underlying IP3R spatial distribution can be modified.