Software programming vs hardware rewiring in intracellular Ca2+ signals

SILVINA PONCE DAWSON

Conferencia; 2017 Annual Meeting of the International Physics of Living Systems (iPoLS) Network; 2017

Calcium signals are ubiquitous. They participate of processes asdiverse as fertilization and cell death. In most situations theyinvolve calcium release from intracellular stores, particularly,through inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs). IP3Rsneed to bind calcium and IP3 to become open. IP3Rs, on the otherhand, get inhibited by high calcium concentrations. These propertiesprovide them with the ability to act as "coincidence" detectors wherethe timing between the relative increase of IP3 and calcium leads tosignals that can propagate or remain localized. This transitionbetween local and global signals also depends on the spatialarrangement of active IP3Rs which, in most cell types, seem to beorganized in clusters that are separated by a 1 or 2 microns. Cellssuch as oocytes change the IP3R spatial distribution withmaturation. In this way calcium waves travel smoothly across the(mature) egg while they are saltatory and can eventually fail topropagate in immature oocytes. The IP3R/Ca2+ channel then providesthe flexibility to the calcium signaling toolkit to operate on twodifferent timescales to change the resulting calcium signal: a "fast"programming mechanism that is controlled by external signals and onethat requires hardware rewiring. In this talk I will discuss anexample of each of these cases.