The combined effect of Ca2+ Removal and Spatial Inhomogeneities on IP3R Mediated Ca2+ Signals

PONCE DAWSON, SILVINA

Congreso; SAFIS 2021; 2021

Calcium (Ca2+) signals are ubiquitous. Most intracellular Ca2+ signals involve the release of Ca2+ from the endoplasmic reticulum (ER) through Inositol 1,4,5-Trisphosphate Receptors (IP3Rs). In this talk I will discuss the results of our investigations on how the interplay between the non-uniform spatial distribution of IP3Rs and the processes that characterize the release, transport, and removal of cytosolic Ca2+ determines the characteristics of the intracellular signals of this ion. More specifically, I will present the results of experiments performed in untreated and in progesterone-treated Xenopus laevis oocytes which show that the propagation is less saltatory in the latter than in the former. Our starting hypothesis was that the different underlying IP3R spatial distributions that have been observed in both cell types could explain the differences in the signal propagation properties. By means of simple mathematical models we determined, however, that the rate of cytosolic Ca2+ removal, which is also different in both cell types, plays a key role on the change of the propagation properties. In particular, it affects the Ca2+-mediated coupling between IP3Rs in such a way that the effect of the underlying (uniform or non-uniform) spatial distribution of the channels can be masked.