Mitochondria from every tissue are quite similar in their capability to accumulate Ca2+ in a process that depends on the electrical potential across the inner membrane; it is catalyzed by a gated channel (named mitochondrial Ca2+ uniporter), the molecular identity of which has only recently been unraveled. The release of accumulated Ca2+ in mitochondria from different tissues is, on the contrary, quite variable, both in terms of speed and mechanism: a Na+-dependent efflux in excitable cells (catalyzed by NCLX) and a H+/Ca2+ exchanger in other cells. The efficacy of mitochondrial Ca2+ uptake in living cells is strictly dependent on the topological arrangement of the organelles with respect to the source of Ca2+ flowing into the cytoplasm, i.e., plasma membrane or intracellular channels. In turn, the structural and functional relationships between mitochondria and other cellular membranes are dictated by the specific architecture of different cells. Mitochondria not only modulate the amplitude and the kinetics of local and bulk cytoplasmic Ca2+ changes but also depend on the Ca2+ signal for their own functionality, in particular for their capacity to produce ATP. In this review, we summarize the processes involved in mitochondrial Ca2+ handling and its integration in cell physiology, highlighting the main common characteristics as well as key differences, in different tissues.
Mitochondrial Ca2+ homeostasis: mechanism, role, and tissue specificities
Filadi Riccardo;Pozzan Tullio
2012
Abstract
Mitochondria from every tissue are quite similar in their capability to accumulate Ca2+ in a process that depends on the electrical potential across the inner membrane; it is catalyzed by a gated channel (named mitochondrial Ca2+ uniporter), the molecular identity of which has only recently been unraveled. The release of accumulated Ca2+ in mitochondria from different tissues is, on the contrary, quite variable, both in terms of speed and mechanism: a Na+-dependent efflux in excitable cells (catalyzed by NCLX) and a H+/Ca2+ exchanger in other cells. The efficacy of mitochondrial Ca2+ uptake in living cells is strictly dependent on the topological arrangement of the organelles with respect to the source of Ca2+ flowing into the cytoplasm, i.e., plasma membrane or intracellular channels. In turn, the structural and functional relationships between mitochondria and other cellular membranes are dictated by the specific architecture of different cells. Mitochondria not only modulate the amplitude and the kinetics of local and bulk cytoplasmic Ca2+ changes but also depend on the Ca2+ signal for their own functionality, in particular for their capacity to produce ATP. In this review, we summarize the processes involved in mitochondrial Ca2+ handling and its integration in cell physiology, highlighting the main common characteristics as well as key differences, in different tissues.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
