Software programming vs hardware rewiring in intracellular Ca2+ signals

SILVINA PONCE DAWSON

Simposio; Coloquios Queen's Belfast University; 2017

Intracellular alcium signals are ubiquitous. They participate ofprocesses as diverse as fertilization and cell death. In mostsituations they involve calcium release from intracellular stores,particularly, through inositol 1,4,5-trisphosphate (IP3) receptors(IP3Rs). IP3Rs need to bind calcium and IP3 to become open. IP3Rs, onthe other hand, get inhibited by high calcium concentrations. Thecalcium released from an open IP3R can then induce the opening ofneighboring channels leading to a propagating signal. The endresponses that such a signal elicits depend on the range ofpropagation. In this talk I will show results of models andexperiments which indicate that cells use (at least) two ?strategies?to change the range of signal propagation. One, which is at work insynaptic plasticity, involves differences in the timing between therelative increase of IP3 and calcium. The other one, which occurs asan oocyte matures into an egg, involves changes in the IP3R spatialdistribution and in the calcium handling mechanisms The examplesillustrate how the IP3R/Ca2+ channel equips the calcium signalingtoolkit with the flexibility to operate on two different timescales tochange the propagation range: a "fast" programming mechanism thatis controlled by external signals and a "slow" one that involves hardwarerewiring.