The calcium-signaling toolkit: Updates needed

Here, we review the role of Ca2 + in apoptosis, namely that ER Ca2 + depletion or a sustained elevation of cytosolic or mitochondrial Ca2 + concentration are sufficient to trigger apoptosis. These concepts have emerged by the use of ER stressor agents that decrease the ER Ca2 + pool by inhibiting SERCA pumps. However, aside from their well-known actions on Ca2 + homeostasis disruption leading to apoptosis, new evidence show that some ER Ca2 + modulators have significant implications in other Ca2 +-mediated or Ca2 +-independent pathways determining cell fate suggesting a more complex regulation of apoptosis by intracellular Ca2 +. Here, we discuss the crucial interplay between Ca2 + mediated apoptosis, the Unfold Protein Response and autophagy determining cell fate, and the molecular compounds that have been used to depict these pathways. This review of the literature clearly shows the need for new inhibitors that do not interfere concomitantly with autophagy and Ca2 + signaling. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.