摘要
Intracellular Ca2+ is vital for cell physiology.Disruption of Ca2+ homeostasis contributes to human diseases such as heart failure,neuron-degeneration,and diabetes.To ensure an effective intracellular Ca2+ dynamics,various Ca2+ transport proteins localized in different cellular regions have to work in coordination.The central role of mitochondrial Ca2+ transport mechanisms in responding to physiological Ca2+ pulses in cytosol is to take up Ca2+ for regulating energy production and shaping the amplitude and duration of Ca2+ transients in various micro-domains.Since the discovery that isolated mitochondria can take up large quantities of Ca2+ approximately 5 decades ago,extensive studies have been focused on the functional characterization and implication of ion channels that dictate Ca2+ transport across the inner mitochondrial membrane.The mitochondrial Ca2+ uptake sensitive to non-specific inhibitors ruthenium red and Ru360 has long been considered as the activity of mitochondrial Ca2+ uniporter(MCU) .The general consensus is that MCU is dominantly or exclusively responsible for the mitochondrial Ca2+ influx.Since multiple Ca2+ influx mechanisms(e.g.L-,T-,and N-type Ca2+ channel) have their unique functions in the plasma membrane,it is plausible that mitochondrial inner membrane has more than just MCU to decode complex intracellular Ca2+ signaling in various cell types.During the last decade,four molecular identities related to mitochondrial Ca2+ influx mechanisms have been identified.These are mitochondrial ryanodine receptor,mitochondrial uncoupling proteins,LETM1(Ca2+ /H+ exchanger) ,and MCU and its Ca2+ sensing regulatory subunit MICU1.Here,we briefly review recent progress in these and other reported mitochondrial Ca2+ influx pathways and their differences in kinetics,Ca2+ dependence,and pharmacological characteristics.Their potential physiological and pathological implications are also discussed.
Intracellular Ca2＋ is vital for cell physiology.Disruption of Ca2＋ homeostasis contributes to human diseases such as heart failure,neuron-degeneration,and diabetes.To ensure an effective intracellular Ca2＋ dynamics,various Ca2＋ transport proteins localized in different cellular regions have to work in coordination.The central role of mitochondrial Ca2＋ transport mechanisms in responding to physiological Ca2＋ pulses in cytosol is to take up Ca2＋ for regulating energy production and shaping the amplitude and duration of Ca2＋ transients in various micro-domains.Since the discovery that isolated mitochondria can take up large quantities of Ca2＋ approximately 5 decades ago,extensive studies have been focused on the functional characterization and implication of ion channels that dictate Ca2＋ transport across the inner mitochondrial membrane.The mitochondrial Ca2＋ uptake sensitive to non-specific inhibitors ruthenium red and Ru360 has long been considered as the activity of mitochondrial Ca2＋ uniporter（MCU） .The general consensus is that MCU is dominantly or exclusively responsible for the mitochondrial Ca2＋ influx.Since multiple Ca2＋ influx mechanisms（e.g.L-,T-,and N-type Ca2＋ channel） have their unique functions in the plasma membrane,it is plausible that mitochondrial inner membrane has more than just MCU to decode complex intracellular Ca2＋ signaling in various cell types.During the last decade,four molecular identities related to mitochondrial Ca2＋ influx mechanisms have been identified.These are mitochondrial ryanodine receptor,mitochondrial uncoupling proteins,LETM1（Ca2＋ /H＋ exchanger） ,and MCU and its Ca2＋ sensing regulatory subunit MICU1.Here,we briefly review recent progress in these and other reported mitochondrial Ca2＋ influx pathways and their differences in kinetics,Ca2＋ dependence,and pharmacological characteristics.Their potential physiological and pathological implications are also discussed.
基金
supported by NIH grants(Grant Nos.HL-033333 and HL093671)to Shey-Shing Sheu
