Mitochondrial calcium signalling and cell death: approaches for assessing the role of mitochondrial Ca2+ uptake in apoptosis.
Local Ca(2+) transfer between adjoining domains of the sarcoendoplasmic reticulum (ER/SR) and mitochondria allows ER/SR Ca(2+) release to activate mitochondrial Ca(2+) uptake and to evoke a matrix [Ca(2+)] ([Ca(2+)](m)) rise. [Ca(2+)](m) exerts control on several steps of energy metabolism to synchronize ATP generation with cell function. However, calcium signal propagation to the mitochondria may also ignite a cell death program through opening of the permeability transition pore (PTP). This occurs when the Ca(2+) release from the ER/SR is enhanced or is coincident with sensitization of the PTP. Recent studies have shown that several pro-apoptotic factors, including members of the Bcl-2 family proteins and reactive oxygen species (ROS) regulate the Ca(2+) sensitivity of both the Ca(2+) release channels in the ER and the PTP in the mitochondria. To test the relevance of the mitochondrial Ca(2+) accumulation in various apoptotic paradigms, methods are available for buffering of [Ca(2+)], for dissipation of the driving force of the mitochondrial Ca(2+) uptake and for inhibition of the mitochondrial Ca(2+) transport mechanisms. However, in intact cells, the efficacy and the specificity of these approaches have to be established. Here we discuss mechanisms that recruit the mitochondrial calcium signal to a pro-apoptotic cascade and the approaches available for assessment of the relevance of the mitochondrial Ca(2+) handling in apoptosis. We also present a systematic evaluation of the effect of ruthenium red and Ru360, two inhibitors of mitochondrial Ca(2+) uptake on cytosolic [Ca(2+)] and [Ca(2+)](m) in intact cultured cells.
Hajnóczky
György
G
Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA. Gyorgy.Hajnoczky@jefferson.edu
Csordás
György
G
Das
Sudipto
S
Garcia-Perez
Cecilia
C
Saotome
Masao
M
Sinha Roy
Soumya
S
Yi
Muqing
M
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008928:Mitochondria / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D015220:Calcium Channels; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C034703:mitochondrial calcium uniporter; D002118:Calcium