Ca2+ and cAMP cross-talk in mitochondria

While mitochondrial Ca2+ homeostasis has been studied for several decades and many of the functional roles of Ca2+ accumulation within the matrix have been at least partially clarified, the possibility of modulation of the organelle functions by cAMP remains largely unknown. In this contribution we briefly summarize the key aspects of Ca2+ and cAMP signalling pathways in mitochondria. In particular, we focus on recent findings concerning the discovery of an autonomous cAMP toolkit within the mitochondrial matrix, its crossroad with mitochondrial Ca2+ signalling and its role in controlling ATP synthesis. The discovery of a cAMP signalling, and the demonstration of a cross-talk between cAMP and Ca2+ inside mitochondria, open the way to a re-evaluation of these organelles as integrators of multiple second messengers. A description of the main methods presently available to measure Ca2+ and cAMP in mitochondria of living cells with genetically encoded probes is also presented.