Quasi-synaptic calcium signal transmission between endoplasmic reticulum and mitochondria

Csordás, György; Thomas, Andrew P.; Hajnóczky, György

doi:10.1093/emboj/18.1.96

Cited by 499 publications

(427 citation statements)

References 68 publications

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“…For fluorescence imaging of [Ca 2ϩ ] c , labeling of cells with fura-C 18 (1 M) was carried out during permeabilization. All of the measurements were performed in the presence of 2 mM succinate, 2 mM MgATP, and an ATPregenerating system composed of 5 mM phosphocreatine and 5 (11). After permeabilization, the cells were washed into fresh buffer without digitonin and incubated in the imaging chamber at 35°C.…”

Section: Methodsmentioning

confidence: 99%

“…Fluorescence imaging was carried out by using an Olympus IX70 inverted microscope [ϫ40, UApo340, numerical aperture (n.a.) 1.35 oil-immersion objective) fitted with a cooled charge-coupled device camera (PXL; Photometrics) and a scanning monochromator (DeltaRAM; PTI, South Brunswick, NJ) under computer control, as described previously (11,22). Simultaneous detection of fura-C18 (340-and 380-nm excitation) and rhod2 (545-nm excitation) fluorescence was achieved by using a multiwavelength beamsplitter͞emission filter combination (Chroma Technology, Brattleboro, VT).…”

Section: Methodsmentioning

confidence: 99%

“…4 and 5), but downstream effects of the individual elementary events have been difficult to resolve. Given the local communication between Ca 2ϩ release channels and adjacent mitochondrial Ca 2ϩ uptake sites, mitochondria have been suggested to respond to spatially confined Ca 2ϩ release (6)(7)(8)(9)(10)(11)(12)(13). Furthermore, if mitochondrial Ca 2ϩ uptake is activated in the effective domain of [Ca 2ϩ ] c sparks and puffs, mitochondria could actively contribute to the organization of elementary calcium signaling in the cytosol.…”

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confidence: 99%

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Ca ²⁺ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Pacher

Thomas

Hajnóczky

2002

Proc. Natl. Acad. Sci. U.S.A.

148

117

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Mitochondrial calcium signaling is important in the control of fundamental cellular functions including energy metabolism and apoptotic cell death (8,(14)(15)(16)(17). Mitochondrial calcium signals often are established by Ca 2ϩ release from sarco-endoplasmic reticulum Ca 2ϩ stores as a result of the strategic localization of the low-affinity mitochondrial Ca 2ϩ uptake sites close to Ca 2ϩ release channels. This machinery has been shown to be effective in delivering Ca 2ϩ to the mitochondria during [Ca 2ϩ ] c spikes (6-8, 10, 11, 18). Furthermore, Duchen et al. (19) monitored changes in mitochondrial membrane potential and demonstrated localized mitochondrial depolarizations in myocytes. Based on the association of depolarizations with contraction and on the effect of Ca 2ϩ transport inhibitors, they concluded that the depolarizations were due to mitochondrial Ca 2ϩ uptake. However, no measurement of localized cytosolic or mitochondrial matrix ([Ca 2ϩ ] m ) signals was shown in the study of Duchen et al. (19). Mitochondrial Ca 2ϩ uptake may be associated with membrane depolarization, but there is no expectation of a relationship between membrane potential and the subsequent duration and decay of mitochondrial Ca 2ϩ , which are the key parameters in the regulation of mitochondrial function. Moreover, mitochondrial Ca 2ϩ uptake can be associated with an increase in membrane potential because of activation of metabolism (8, 20). Thus, it is of critical importance to measure mitochondrial Ca 2ϩ directly and to address the question of whether brief opening of a few release channels during elementary Ca 2ϩ release events, such as ryanodine receptor (RyR)-mediated Ca 2ϩ sparks and IP 3 receptor-mediated Ca 2ϩ puffs, is sufficient to trigger [Ca 2ϩ ] m increases. The extent to which [Ca 2ϩ ] c sparks and puffs propagate to the mitochondria is a critical parameter for understanding the control of mitochondrial Ca 2ϩ targets and the local feedback exerted by mitochondrial Ca 2ϩ uptake on [Ca 2ϩ ] c . Using confocal microscopy and compartmentalized rhod2 to image [Ca 2ϩ ] at the level of individual mitochondria for the first time, we were able to record the elementary units of the [Ca 2ϩ ] m signal and to study how the miniature [Ca 2ϩ ] m rise is integrated into intracellular Ca 2ϩ regulation. Experimental ProceduresCells and Solutions. H9c2 cardiac cells were cultured, plated for imaging, and allowed to differentiate to myotubes as described previously (21,22). Before use, the cells were preincubated for 30 min in extracellular medium composed of 121 mM NaCl, 5 mM NaHCO 3 , 10 mM Na⅐Hepes, 4.7 mM KCl, 1.2 mM KH 2 PO 4 , 1.2 mM MgSO 4 , 2 mM CaCl 2 , 10 mM glucose, and 2% BSA (pH 7.4) at 37°C. Loading with the dyes was carried out in the same buffer. For measurements of [Ca 2ϩ ] m in permeabilized myotubes, the cells were loaded with 4 M rhod2͞AM in the presence of 0.003% (wt͞vol) pluronic acid at 37°C for 50 min. Dye-loaded cells were washed with Ca 2ϩ -free extracellular buffer composed of 120 mM NaCl, 20 mM Na⅐...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Ca ²⁺ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Pacher

Thomas

Hajnóczky

2002

Proc. Natl. Acad. Sci. U.S.A.

148

117

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“…Besides the rER, the mitochondria-associated membrane (MAM) is most highly enriched in ER chaperones and oxidoreductases (Hayashi et al 2009). The MAM is the location where phosphatidylserine biosynthesis and its transfer to mitochondria occur (Shiao et al 1998;Stone and Vance 2000), but also contains calcium handling proteins, such as the inositol 1,4,5-trisphosphate receptor (IP3R) (Csordas et al 1999;Hajnoczky et al 2000). On the MAM, ER chaperones and oxidoreductases appear to regulate the ER calcium content.…”

Section: Introductionmentioning

confidence: 99%

Ero1α requires oxidizing and normoxic conditions to localize to the mitochondria-associated membrane (MAM)

Gilady

Bui

Lynes

et al. 2010

Cell Stress and Chaperones

156

115

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Protein secretion from the endoplasmic reticulum (ER) requires the enzymatic activity of chaperones and oxidoreductases that fold polypeptides and form disulfide bonds within newly synthesized proteins. The best-characterized ER redox relay depends on the transfer of oxidizing equivalents from molecular oxygen through ER oxidoreductin 1 (Ero1) and protein disulfide isomerase to nascent polypeptides. The formation of disulfide bonds is, however, not the sole function of ER oxidoreductases, which are also important regulators of ER calcium homeostasis. Given the role of human Ero1α in the regulation of the calcium release by inositol 1,4,5-trisphosphate receptors during the onset of apoptosis, we hypothesized that Ero1α may have a redox-sensitive localization to specific domains of the ER. Our results show that within the ER, Ero1α is almost exclusively found on the mitochondria-associated membrane (MAM). The localization of Ero1α on the MAM is dependent on oxidizing conditions within the ER. Chemical reduction of the ER environment, but not ER stress in general leads to release of Ero1α from the MAM. In addition, the correct localization of Ero1α to the MAM also requires normoxic conditions, but not ongoing oxidative phosphorylation.

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“…Mitochondria are temporo-spatial modulators of cytosolic [Ca 2ϩ ] through their ability to both sequester and release Ca 2ϩ in concert with Ca 2ϩ transport across the endoplasmic reticulum (1,2). Physiological mitochondrial Ca 2ϩ efflux, including that caused by Ca 2ϩ -induced Ca 2ϩ release (mCICR), 1 is attributed to either activation of the permeability transition pore (PTP) (3,4) or to reversal of the Ca 2ϩ uniporter (5).…”

mentioning

confidence: 99%

Cyclosporin A-insensitive Permeability Transition in Brain Mitochondria

Chinopoulos

Starkov

Fiskum

2003

Journal of Biological Chemistry

123

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The mitochondrial permeability transition pore (PTP) may operate as a physiological Ca 2؉ release mechanism and also contribute to mitochondrial deenergization and release of proapoptotic proteins after pathological stress, e.g. ischemia/reperfusion. Brain mitochondria exhibit unique PTP characteristics, including relative resistance to inhibition by cyclosporin A. In this study, we report that 2-aminoethoxydiphenyl borate blocks Ca 2؉ -induced Ca 2؉ release in isolated, non-synaptosomal rat brain mitochondria in the presence of physiological concentrations of ATP and Mg 2؉ . Ca 2؉ release was not mediated by the mitochondrial Na ؉ /Ca 2؉ exchanger or by reversal of the uniporter responsible for energy-dependent Ca 2؉ uptake. Loss of mitochondrial Ca 2؉ was accompanied by release of cytochrome c and pyridine nucleotides, indicating an increase in permeability of both the inner and outer mitochondrial membranes. Under these conditions, Ca 2؉ -induced opening of the PTP was not blocked by cyclosporin A, antioxidants, or inhibitors of phospholipase A 2 or nitric-oxide synthase but was abolished by pretreatment with bongkrekic acid. These findings indicate that in the presence of adenine nucleotides and Mg 2؉ , Ca 2؉ -induced PTP in non-synaptosomal brain mitochondria exhibits a unique pattern of sensitivity to inhibitors and is particularly responsive to 2-aminoethoxydiphenyl borate.Mitochondria are temporo-spatial modulators of cytosolic [Ca 2ϩ ] through their ability to both sequester and release Ca 2ϩ in concert with Ca 2ϩ transport across the endoplasmic reticulum (1, 2). Physiological mitochondrial Ca 2ϩ efflux, including that caused by Ca 2ϩ -induced Ca 2ϩ release (mCICR), 1 is attributed to either activation of the permeability transition pore (PTP) (3, 4) or to reversal of the Ca 2ϩ uniporter (5). Opening of the PTP has been implicated as a mediator of apoptotic and necrotic cell death as well as a regulator of normal cell Ca 2ϩ homeostasis (4, 6 -12). The characteristic traits of the PTP include reversibility (13), sensitivity to inhibition by cyclosporin A (14), and mitochondrial swelling associated with loss of matrix solutes (15-17). Cyclosporin A is not always effective, however, at inhibiting Ca 2ϩ -induced mitochondrial swelling and loss of ⌬⌿ (18 -22). In addition, the observation that normal intracellular concentrations of adenine nucleotides and Mg 2ϩ partially or completely block PTP activation (23, 24) casts doubt on a physiological role of the PTP.The extent to which mitochondria swell in response to accumulation of large Ca 2ϩ loads also varies considerably with experimental conditions and with mitochondrial tissue type (25-27). Brain mitochondria are particularly resistant to Ca 2ϩ -induced swelling (25, 28); moreover, they represent many cell populations, which may explain their heterogeneous response to large Ca 2ϩ loads and to inhibitors of the PTP, e.g. cyclosporin A (26,29).In this study we report that 2-APB (30) prevents Ca 2ϩ -induced PTP in non-synaptosomal brain mitochondria in the ...

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Quasi-synaptic calcium signal transmission between endoplasmic reticulum and mitochondria

Cited by 499 publications

References 68 publications

Ca ²⁺ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Ca ²⁺ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Ero1α requires oxidizing and normoxic conditions to localize to the mitochondria-associated membrane (MAM)

Cyclosporin A-insensitive Permeability Transition in Brain Mitochondria

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Quasi-synaptic calcium signal transmission between endoplasmic reticulum and mitochondria

Cited by 499 publications

References 68 publications

Ca 2+ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Ca 2+ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Ero1α requires oxidizing and normoxic conditions to localize to the mitochondria-associated membrane (MAM)

Cyclosporin A-insensitive Permeability Transition in Brain Mitochondria

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Ca ²⁺ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors

Ca ²⁺ marks: Miniature calcium signals in single mitochondria driven by ryanodine receptors