Modulation of calcium signalling by mitochondria

In this review we will attempt to summarise the complex and sometimes contradictory effects that mitochondria have on different forms of calcium signalling. Mitochondria can influence Ca2+ signalling indirectly by changing the concentration of ATP, NAD(P)H, pyruvate and reactive oxygen species - which in turn modulate components of the Ca2+ signalling machinery i.e. buffering, release from internal stores, influx from the extracellular solution, uptake into cellular organelles and extrusion by plasma membrane Ca2+ pumps. Mitochondria can directly influence the calcium concentration in the cytosol of the cell by importing Ca2+ via the mitochondrial Ca2+ uniporter or transporting Ca2+ from the interior of the organelle into the cytosol by means of Na+/Ca2+ or H+/Ca2+ exchangers. Considerable progress in understanding the relationship between Ca2+ signalling cascades and mitochondrial physiology has been accumulated over the last few years due to the development of more advanced optical techniques and electrophysiological approaches.