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MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS
1Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio; Departments of 2Medicine, 3Biochemistry, 4Dental Diagnostic Science, and 5Radiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas; and 6Department of Neurology, University of Virginia Health Sciences Center, Charlottesville, Virginia
Submitted 8 July 2005 ; accepted in final form 15 December 2005
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ABSTRACT |
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arachidonic acid; mitochondrial Ca2+ uniporter; G protein-coupled receptor; IP3 receptor
At the cellular level, excessive FA can increase oxidative stress, influence ion channel activities, activate multiple kinase pathways, and induce apoptosis. All of these cellular effects of FA may contribute to the altered physiological functions of different tissues observed in association with lipid overload. Production of reactive oxygen species by polyunsaturated FA (PUFA) has been reported in HL-60 and HeLa cells (23, 24, 26, 59), neutrophils (11), and human breast carcinoma cells (6, 13, 70). PUFA-stimulated reactive oxygen species production in some cells has been shown to be mediated by NADPH oxidase activation (1).
The induction of apoptosis by FA has been reported in a variety of cells. In human retinoblastoma Y79 cells apoptosis is induced by arachidonic acid (AA) through the action of its oxidative metabolites (73). In contrast, AA-induced apoptosis in chronic myeloid leukemia cells does not require AA metabolism (55). AA is also partially responsible for the apoptotic effect of oxidized LDL in the macrophage cell line Chinese hamster ovary-K1 (48). Saturated FA, such as palmitic acid (PA) and stearic acid, induce apoptosis in human granulosa cells and cause downregulation of Bcl-2 and upregulation of Bax proteins (47). It has been shown in LLCPKc14 cells that AA causes apoptosis through increased production of ceramide (9). Docosahexaenoic acid (DHA) induces apoptosis in Jurkat cells by a protein phosphatase 1- and 2B-sensitive mechanism (67). In mitochondria isolated from rat liver, both AA and PA cause the opening of the mitochondrial permeability transition pore (MPT), a process leading to apoptosis (51, 64). These studies suggest that FA induce apoptosis by diverse mechanisms.
Growing evidence indicates that excessive concentrations of FA affect cell functions by altering the activities of various ion transporters and channels, including proton, K+, Na+, Cl–, and Ca2+ currents, as well as nonselective cation channels and the cardiac Na+/Ca2+ exchanger (17, 25, 28, 36, 44, 63, 74). PUFA inhibit voltage-dependent Ca2+ channels in cardiac myocytes (17), retinal glial cells (4), and sympathetic neurons (39). The mechanisms by which PUFA modulate ion channels vary among different cell types and different channels. PUFA may directly bind and modulate the activity of some channels, whereas in other cases, PUFA regulate channel activities indirectly through metabolites and protein kinases (58). FA exert diverse effects on the transient receptor potential (TRP) or TRP-like families of Ca2+ channels (75). PUFA have been demonstrated to be reversible agonists for TRP and TRP-like channels (TRPC) in both Drosophila photoreceptors and Drosophila S2 cells (10). TRP channels in mammalian cells are composed of seven subfamilies, including TRPC, TRP vanilloid, and TRP melastatin (45). Some TRPC channels may be involved in the capacitative or store-operated Ca2+ entry during classic phospholipase C (PLC)-inositol-1,4,5-trisphosphate (IP3)-mediated cytosolic, or intracellular, Ca2+ ([Ca2+]i) signaling (75, 78). AA and other PUFA either inhibit or stimulate the store-operated Ca2+ influx during G protein-coupled receptor (GPCR)-mediated [Ca2+]i mobilization depending on the cell type and the nature of the channel (58).
PUFA-induced [Ca2+]i mobilization has also been observed in vascular endothelial and human embryonic kidney (HEK)-293 cells (33, 40, 65). In HEK-293 cells, [Ca2+]i mobilization induced by AA and other PUFA involves activation of the AA-specific Ca2+ influx pathway Iavc (40, 65). In the presence of 10 µM Gd3+ AA- but not carbachol- or thapsigargin-mediated Ca2+ release was completely inhibited in HEK-293 cells, suggesting that AA-induced Ca2+ release in these cells may be mediated by a process distinct from the traditional PLC-IP3 pathways (40). However, the mechanism of PUFA-induced [Ca2+]i mobilization remains unclear.
In this study, experiments have been designed to clarify the role of the classic PLC-IP3 pathway and other Ca2+ transport pathways in FA-mediated [Ca2+]i mobilization. We have found that PUFA but not monounsaturated or saturated FA cause [Ca2+]i mobilization in NT2 human teratocarcinoma cells. Unlike the [Ca2+]i response to the muscarinic agonist carbachol, PUFA-mediated [Ca2+]i mobilization in NT2 cells is independent of PLC and IP3 receptor activation, as well as IP3-sensitive internal Ca2+ stores. Furthermore, PUFA-mediated [Ca2+]i mobilization is inhibited by the mitochondrial uncoupler carboxyl cyanide m-chlorophenylhydrozone (CCCP). Direct measurements of mitochondrial Ca2+ with X-rhod-1 and 45Ca2+ indicate that PUFA induce Ca2+ efflux from mitochondria. These experiments suggest that PUFA-gated Ca2+ release from mitochondria is the underlying mechanism for PUFA-induced [Ca2+]i mobilization in NT2 cells.
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MATERIALS AND METHODS |
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Cell culture. NT2 cells were plated at a density of 104 cells/cm2 and cultured in 100 mm dishes in Dulbecco's modified Eagle's medium, supplemented with 10% fetal calf serum and penicillin (10 U/ml)/streptomycin (10 µg/ml), at 37°C in a humidified 5% CO2-atmosphere incubator. Cells grown to near confluence were harvested with trypsin (0.05%)-EDTA (0.02%) and suspended in PBS solutions for use in experiments described below.
Human aortic endothelial cells (HAEC) were plated at a density of 6 x 103/cm2 in 75-ml flasks in MDCB-131, supplemented with 15 mM HEPES, 14 mM NaHCO3, EGF (10 ng/ml), fibroblast growth factor (2.5 ng/ml), hydrocortisone (1 µg/ml), 10% fetal calf serum, and penicillin (10 U/ml)/streptomycin (10 µg/ml), and cultured at 37°C in a humidified 5% CO2-atmosphere incubator. After 1 wk of culture, when the cells reached confluence, HAEC were harvested with trypsin (0.05%)-EDTA (0.02%) and labeled with fura-2 AM for measurement of [Ca2+]i in cell suspensions or used to isolate mitochondria to measure [Ca2+]m with X-rhod-1.
Measurement of [Ca2+]i in suspensions of NT2 cells. NT2 cells suspended in a buffer containing (in mM) 140 NaCl, 5 KCl, 1 CaCl2, 1 MgCl2, 1.2 KH2PO4, 10 glucose, and 10 HEPES, pH 7.4, were loaded with fura-2 AM (2 µM) at 37°C for 30 min with gentle shaking. Loaded cells were washed with 5 volumes of PBS supplemented with 1 mM CaCl2 and 1 mM MgSO4 (PBS1Ca). Alterations in [Ca2+]i were measured by changes in fluorescence ratio with emission wavelength of 510 nm and excitation wavelengths of 340 and 380 nm. Fura-2-loaded cells in suspension were incubated at 37°C in a cuvette with a magnetic stirrer, and changes of fluorescence ratio were monitored in a fluorometer manufactured by Photon Technology International (PTI; Lawrenceville, NJ). For measurement of [Ca2+]i in the absence of extracellular Ca2+, fura-2-loaded NT2 cells were washed with 5 volumes of PBS supplemented with 200 µM EGTA (pH 7.4) and 1 mM MgSO4 (PBS0Ca) immediately before experiments; [Ca2+]i measurements were performed in PBS0Ca solutions (76).
Measurement of mitochondrial Ca2+ in suspensions of NT2 cells. NT2 cells suspended in PBS were double labeled with X-rhod-1 AM (2 µM) and BAPTA-AM (50 µM), or labeled with X-rhod-1 AM alone, at 37°C for 30 min with gentle shaking. The loaded cells were washed with 5 volumes of PBS1Ca. Alterations in mitochondrial Ca2+ ([Ca2+]m) were measured by changes in fluorescence intensity with emission wavelength of 602 nm and excitation wavelength of 578 nm. X-rhod-1-AM- and BAPTA-AM-loaded cells were incubated in PBS supplemented with 2 mM EGTA (pH 7.4) and 1 mM MgSO4 at 37°C in a cuvette in the presence of constant magnetic stirring; cells loaded with X-rhod-1 alone were incubated in PBS supplemented with 2 mM EGTA/1 mM MgSO4 or in PBS1Ca. Changes of X-rhod-1 fluorescence intensity were monitored in a PTI fluorometer.
Measurement of [Ca2+]m in isolated mitochondria from NT2 cells and HAEC. Mitochondria from NT2 cells were isolated as described previously (30). Briefly, NT2 cells from seven to ten 100-mm dishes were suspended in PBS, incubated on ice, and centrifuged at 1,000 rpm for 15 min at 4°C in an Eppendorf 5804R centrifuge. Cells were resuspended in 2 ml ice-cold mitochondria isolation buffer containing 250 mM mannitol, 75 mM succinic acid, 100 µM EDTA, 0.5 mM EGTA, 10 mM HEPES, pH 7.5 (MB1). The cell suspensions were homogenized manually with 15–20 strokes in a glass-glass homogenizer. The homogenates were centrifuged at 1,000 rpm for 15 min at 4°C. The supernatants were collected and centrifuged at 10,000 g for 20 min at 4°C. The pellets were resuspended in 500 µl of MB1 and diluted to a final volume of 3 ml with PBS1Ca. The mitochondria suspensions were labeled with the mitochondrial Ca2+ fluorescent indicator X-rhod-1 AM (2 µM) at 37°C for 30 min, after which the mixtures were centrifuged at 10,000 g at room temperature in a tabletop high-speed centrifuge (Savant Instruments, Farmingdale, NY) for 10 min. The labeled mitochondria were resuspended in PBS1Ca and used for measurement of [Ca2+]m. Alterations of [Ca2+]m in suspensions of isolated mitochondria were measured by changes in fluorescence intensity with emission wavelength of 602 nm and excitation wavelength of 578 nm. X-rhod-1 loaded mitochondria were incubated in PBS0Ca at 37°C in a cuvette in the presence of continuous magnetic stirring, and changes of X-rhod-1 fluorescence intensity were monitored in a PTI fluorometer. The same procedure was adopted to isolate mitochondria and measure [Ca2+]m from HAEC, except that the cells were grown in 75-ml flasks.
Measurement of PUFA-induced Ca2+ efflux in isolated mitochondria using 45Ca2+. Loading of 45Ca2+ into mitochondria was performed according to a previously reported procedure (8) with modification. Briefly, isolated mitochondria (0.4–1.2 mg protein) were resuspended in 500 µl of MB1, diluted to a final volume of 3 ml with PBS1Ca, and loaded with 45Ca2+ at 37°C for 30 min with gentle agitation. The 45Ca2+-loaded mitochondria were then diluted in 10 volumes of PBS0Ca-containing vehicle or 10 µg/ml PUFA or palmitic acid (PA). The mixtures were incubated at 37°C for 5 min and the 45Ca2+ contents remaining in the mitochondria were counted in a liquid scintillation counter.
Data analysis. Individual figures shown in RESULTS are representative of at least three experiments. Statistical analysis of 45Ca2+ measurements was performed using the Wilcoxon scores for variable assay and Monte Carlo estimate for significance.
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RESULTS |
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TOPABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONGRANTSREFERENCES |
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The effects of CCCP observed in NT2 cells suggest that PUFA-induced [Ca2+]i mobilization requires functional mitochondria. To determine how mitochondria are involved in the PUFA response, we compared the change of [Ca2+]m during carbachol and PUFA treatment of NT2 cells. In these experiments, intact NT2 cells were labeled with the mitochondrial Ca2+ indicator X-rhod-1 and the fluctuation in cytosolic Ca2+ was buffered with BAPTA. In BAPTA and X-rhod-1 double-labeled cells, stimulation of the cells with carbachol had no effect on X-rhod-1 fluorescence in the absence of extracellular Ca2+ (Fig. 8A), indicating that activation of the traditional GPCR-PLC-IP3 pathway under the experimental conditions used had no effect on [Ca2+]m. In contrast, in the same cells in which carbachol had no effect on [Ca2+]m subsequent treatment with AA (10 µg/ml) caused a reduction in X-rhod-1 fluorescence (Fig. 8B), suggesting a reduction in [Ca2+]m in intact NT2 cells by AA. Under the same conditions, the saturated FA PA (10 µg/ml) showed no effect on X-rhod-1 fluorescence (Fig. 8C), whereas the PUFA LA also caused a reduction in X-rhod-1 fluorescence (Fig. 8D). These results suggest that PUFA but not carbachol or saturated FA cause Ca2+ release from mitochondria in intact NT2 cells.
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Additional experiments were conducted to compare the effects of carbachol and PUFA on X-rhod-1 signals in NT2 cells in the absence of BAPTA. In the presence of extracellular Ca2+, carbachol caused a transient increase in [Ca2+]i, followed by an elevated plateau, indicating a typical GPCR response, whereas AA caused a more gradual increase of [Ca2+]i (Fig. 8G). The AA response observed may represent the sum of the change in cytosolic and mitochondrial Ca2+. In Ca2+-free media, both carbachol and AA caused increases in [Ca2+]i without BAPTA (Fig. 8H). However, after carbachol-induced [Ca2+]i decayed to basal levels, addition of AA caused a reduction in X-rhod-1 signal (Fig. 8H). This observation is consistent with a decrease of [Ca2+]m under conditions of enhanced removal of [Ca2+]i by the endoplamic reticulum and plasma membrane Ca2+-ATPase, which has been reported to be activated during GPCR stimulation in other cell types (62, 77).
To confirm that PUFA may induce [Ca2+]i mobilization by causing Ca2+ release from mitochondria, we examined the effect of PUFA in isolated mitochondria using both the mitochondrial Ca2+ indicator X-rhod-1 and 45Ca2+. In these experiments, mitochondria were prepared from NT2 cells and labeled with X-rhod-1 or 45Ca2+ in the presence of high concentration of Ca2+ (PBS1Ca buffer). The labeled mitochondria were then treated with PUFA and alterations in [Ca2+]m were measured by X-rhod-1 fluorescence or by the remaining 45Ca2+ content in the mitochondria. As demonstrated in Fig. 9A, DHA caused a concentration-dependent release of Ca2+ from mitochondria, as measured by X-rhod-1 fluorescence; LA and AA had similar effects (data not shown). Measurement of 45Ca2+ indicated that AA and LA but not PA also caused a significant reduction in mitochondrial 45Ca2+ content (Fig. 9B). Compared with control, AA and LA reduced the 45Ca2+ content by 36.3 ± 12.4% (P = 0.0079, n = 5 measurements) and 35.9 ± 10.6% (P = 0.0039, n = 6), respectively, whereas PA had no significant effect on mitochondrial 45Ca2+ content (P = 0.1256 vs. control, n = 5).
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DISCUSSION |
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In several cell types, CCCP increases [Ca2+]i by causing Ca2+ release from mitochondria (7, 12, 20, 29, 34, 49, 60, 67, 72). CCCP is a mitochondrial uncoupler that collapses the proton gradient across the mitochondrial inner membrane and thus eliminates the driving force for mitochondrial Ca2+ uptake. In addition, Ca2+ efflux from mitochondria requires the opening of a conducting pathway for Ca2+ exit. During GPCR-stimulated [Ca2+]i mobilization CCCP prevents mitochondrial Ca2+ uptake, which leads to inhibition of the store-operated or capacitative Ca2+ influx. Consistently in NT2 cells CCCP eliminated the plateau phase of carbachol-mediated [Ca2+]i mobilization, indicating the inhibition of store-operated Ca2+ influx (Fig. 7F). The effect of CCCP on [Ca2+]i in resting cells has been found to vary among different cell types. For example, in studies (20) of pancreatic acinar cells, CCCP did not induce [Ca2+]i signals in resting cells but did prevent mitochondrial Ca2+ uptake and cause [Ca2+]i mobilization in agonist-stimulated cells. In chromaffin cells, CCCP triggered [Ca2+]i mobilization and reduced [Ca2+]m under resting conditions (46), indicating that in some cell types, energized mitochondria retain higher concentrations of ionic Ca2+ than the cytosol even in the resting state. Direct measurement of [Ca2+] in mitochondria with low-affinity aequorin yields a value of 5.8 µM (46), which is >50-fold higher than the normal resting [Ca2+]i. Thus mitochondria may be an independent intracellular Ca2+ store. It is known that the two intracellular Ca2+ stores, i.e., the mitochondrial Ca2+ pool and the IP3-sensitive endoplasmic reticulum pool, are dynamically linked by their structural proximity during [Ca2+]i mobilization (57). Part of the Ca2+ released from the endoplasmic reticulum by the IP3-gated channels is taken up by mitochondria (68), leading to increased [Ca2+]m. The increase in [Ca2+]m upregulates the activities of multiple enzymes involved in energy production, as indicated by changes in mitochondrial reduction-oxidation substrates (21, 68). On the other hand increased Ca2+ uptake into mitochondria and/or [Ca2+]m also sensitize cells for the induction of apoptosis by proapoptotic factors (69). Mitochondrial Ca2+ uptake and subsequent efflux also modify the amplitude, duration, localization, and propagation of cytosolic Ca2+ transients (15, 19, 27, 71). In this study, we provide evidence that mitochondria may serve as an independent intracellular source for PUFA-responsive [Ca2+]i mobilization in NT2 cells. CCCP-induced [Ca2+]i mobilization was observed in resting NT2 cells (Fig. 6). The CCCP-mediated [Ca2+]i signal in these cells may occur by elimination of the driving force for Ca2+ uptake, i.e., the proton gradient, and opening of a conducting pathway such as the mitochondrial Ca2+-induced Ca2+ release process (46) or Ca2+ leak along the Ca2+ gradient between mitochondria and cytosol. PUFA-induced mitochondrial Ca2+ release and [Ca2+]i mobilization in NT2 cells may occur by depolarization of the mitochondrial proton gradient through an uncoupling protein-dependent mechanism (32) and/or opening of the MPT for Ca2+ exit (41, 50, 64). Pretreatment of NT2 cells with CCCP inhibits subsequent PUFA-induced [Ca2+]i mobilization probably by causing Ca2+ efflux from mitochondria and depletion of the mitochondrial Ca2+ pool (Fig. 7).
In this study, we used U73122 [GenBank] and 2-APB to examine the involvement of the classic PLC-IP3 signaling pathway in PUFA-induced [Ca2+]i mobilization. U73122 [GenBank] is a synthetic aminosteroid PLC inhibitor. The specificity of the inhibitor toward PIP2 specific PLCs has been validated by numerous studies (22, 38, 53, 54, 75) from different laboratories that had used various cell types. We observed that treatment of NT2 cells with U73122 [GenBank] completely blocked carbachol-induced [Ca2+]i mobilization but had no effect on the PUFA response (Fig. 3). The results confirm that as in other cell types, U73122 [GenBank] specifically targets the GPCR-PLC-IP3 signaling pathway in NT2 cells; [Ca2+]i mobilization mediated by other mechanisms, such as PUFA-induced Ca2+ efflux from mitochondria, is unaffected (Fig. 3). Although 2-APB was originally reported as a cell permeable IP3 receptor antagonist (43), recent studies (3, 37) demonstrated effects of this agent on other pathways that may or may not be related to PLC-IP3-mediated [Ca2+]i mobilization. Moreover, inhibition of IP3 receptor-mediated Ca2+ release by 2-APB has been shown to be variable among different cell types (3, 37). The inhibitory effect of 2-APB may depend on the isoforms of IP3 receptors expressed in the cell and the cytosolic concentrations of IP3 during agonist stimulation (3). In NT2 cells 2-APB effectively blocked [Ca2+]i mobilization in response to carbachol but not PUFA (Fig. 4). 2-APB was found to reduce the rate of the initial rise of PUFA-induced [Ca2+]i mobilization by 80% (Fig. 4). This action of 2-APB could result from a nonspecific effect on mitochondria, insofar as 2-APB has been suggested to inhibit mitochondrial Ca2+ efflux in Jurkat T cells (52a).
Multiple mitochondrial pathways, including the Na+/Ca2+ and H+/Ca2+ exchangers, the Ca2+ uniporter, as well as the MPT, are capable of transporting Ca2+ out of mitochondria (14, 52, 56). Opening of MPT by PUFA and other FA has been reported in isolated mitochondria (2). The MPT is theoretically permeable to Ca2+ and other small molecules, which makes the MPT a possible candidate for mediating PUFA-induced Ca2+ efflux. In addition, the opening of MPT by PUFA may collapse the mitochondrial membrane potential and proton gradients and thus indirectly activate the reversal mode of the Ca2+ uniporter, or affect the activities of the Na+/Ca2+ and/or H+/Ca2+ exchangers, to release mitochondrial Ca2+. We have found that PUFA depolarize mitochondrial membrane potential in intact NT2 cells (data not shown). However, preincubation of NT2 mitochondria with CsA and BA had no effect on PUFA-induced Ca2+ efflux (Fig. 11), suggesting that the MPT and other pathways indirectly linked with MPT through mitochondrial membrane potential may not be involved in PUFA-mediated mitochondrial Ca2+ efflux. This does not exclude the possibility that PUFA might directly activate mitochondrial Ca2+ transporters to release Ca2+ in Ca2+-loaded mitochondria. Indeed, as we have demonstrated, the addition of ruthenium red to block the mitochondrial Ca2+ uniporter inhibited LA-induced mitochondrial Ca2+ efflux, implicating the involvement of the Ca2+ uniporter in PUFA-mediated mitochondrial Ca2+ efflux (Fig. 11). The Na+/Ca2+ exchanger blocker CGP37157 did not affect LA-induced [Ca2+]i mobilization in NT2 cells (data not shown). PUFA and other FA may also depolarize the mitochondrial membrane potential by uncoupling protein 2 (UCP-2)-dependent mechanisms. However, the UCP-2 pathways are unlikely to be the underlying mechanism for PUFA-induced mitochondrial Ca2+ efflux because saturated and monounsaturated FA activate the UCP-2 pathway in other systems (35) but had no effect on [Ca2+]i in NT2 cells and [Ca2+]m in isolated mitochondria (Figs. 1 and 8). Additional studies are ongoing to define the role of the mitochondrial Ca2+ uniporter and possibly other transporters in PUFA-mediated mitochondrial Ca2+ efflux.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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REFERENCES |
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TOPABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONGRANTSREFERENCES |
|---|
2. Bernardi P. Mitochondrial transport of cations: channels, exchangers, and permeability transition. Physiol Rev 79: 1127–1155, 1999.
3. Bootman MD, Collins TJ, Mackenzie L, Roderick HL, Berridge MJ, and Peppiatt CM. 2-Aminoethoxydiphenyl borate (2-APB) is a reliable blocker of store-operated Ca2+ entry but an inconsistent inhibitor of InsP3-induced Ca2+ release. FASEB J 16: 1145–1150, 2002.
4. Bringmann A, Schopf S, Faude F, and Reichenbach A. Arachidonic acid-induced inhibition of Ca2+ channel currents in retinal glial (Müller) cells. Graefes Arch Clin Exp Ophthalmol 239: 859–864, 2001.[Web of Science][Medline]
5. Campbell PJ, Carlson MG, and Nurjhan N. Fat metabolism in human obesity. Am J Physiol Endocrinol Metab 266: E600–E605, 1994.
6. Chajes V, Sattler W, Stranzl A, and Kostner GM. Influence of n-3 fatty acids on the growth of human breast cancer cells in vitro: relationship to peroxides and vitamin-E. Breast Cancer Res Treat 34: 199–212, 1995.[CrossRef][Web of Science][Medline]
7. Chan C, Harland ML, Webb SE, Chen J, Miller AL, and Barritt GJ. Evaluation, using targeted aequorins, of the roles of the endoplasmic reticulum and its (Ca2+ + Mg2+)ATP-ases in the activation of store-operated Ca2+ channels in liver cells. Cell Calcium 35: 317–331, 2004.[CrossRef][Web of Science][Medline]
8. Chang L, Xu J, Yu F, Zhao J, Tang X, and Tang C. Taurine protected myocardial mitochondria injury induced by hyperhomocysteinemia in rats. Amino Acids 27: 37–48, 2004.[CrossRef][Web of Science][Medline]
9. Chen JK, Capdevila J, and Harris RC. Cytochrome p450 epoxygenase metabolism of arachidonic acid inhibits apoptosis. Mol Cell Biol 21: 6322–6331, 2001.
10. Chyb S, Raghu P, and Hardie RC. Polyunsaturated fatty acids activate the Drosophila light-sensitive channels TRP and TRPL. Nature 397: 255–259, 1999.[CrossRef][Web of Science][Medline]
11. Corey SJ and Rossoff PM. Unsaturated fatty acids and lipoxygenase products regulate phagocytic NADPH oxidase activity by a nondetergent mechanism. J Lab Clin Med 118: 343–351, 1991.[Web of Science][Medline]
12. Cristóvão AJ, Capela AN, and Carvalho CM. Ca2+ stores in the chick embryo retina cells. Cell Signal 9: 97–103, 1997.[CrossRef][Web of Science][Medline]
13. Das UN, Begin ME, Ells G, Huang YS, and Horrobin DF. Polyunsaturated fatty acids augment free radical generation in tumor cells in vitro. Biochem Biophys Res Commun 145: 15–24, 1987.[CrossRef][Web of Science][Medline]
14. Deryabina YI, Isakova EP, and Zvyagilskaya RA. Mitochondrial calcium transport systems: properties, regulation, and taxonomic features. Biochemistry 69: 91–102, 2004.[CrossRef][Medline]
15. Duchen MR. Contributions of mitochondria to animal physiology: from homeostatic sensor to calcium signalling and cell death. J Physiol 516: 1–17, 1999.
16. Dulin NO, Sorokin A, and Douglas JG. Arachidonate-induced tyrosine phosphorylation of epidermal growth factor receptor and Shc-Grb2-Sos association. Hypertension 32: 1089–1093, 1998.
17. Ferrier GR, Redondo I, Zhu J, and Murphy MG. Differential effects of docosahexaenoic acid on contractions and L-type Ca2+ current in adult cardiac myocytes. Cardiovasc Res 54: 601–610, 2002.
18. Flarsheim CE, Grupp IL, and Matlib MA. Mitochondrial dysfunction accompanies diastolic dysfunction in diabetic rat heart. Am J Physiol Heart Circ Physiol 271: H192–H202, 1996.
19. Friel DD and Tsien RW. An FCCP-sensitive Ca2+ store in bullfrog sympathetic neurons and its participation in stimulus-evoked changes in [Ca2+]i. J Neurosci 14: 4007–4024, 1994.[Abstract]
20. González A, Schulz I, and Schmid A. Agonist-evoked mitochondrial Ca2+ signals in mouse pancreatic acinar cells. J Biol Chem 275: 38680–38686, 2000.
21. Hajnócky G, Robb-Gaspers LD, Seitz MB, and Thomas AP. Decoding of cytosolic calcium oscillations in the mitochondria. Cell 82: 415–424, 1995.[CrossRef][Web of Science][Medline]
22. He YY, Huang JL, and Chignell CF. Delayed and sustained activation of extracellular signal-regulated kinase in human keratinocytes by UVA: implications in carcinogenesis. J Biol Chem 279: 53867–53874, 2004.
23. Healy DA, Watson RW, and Newsholme P. Polyunsaturated and monounsaturated fatty acids increase neutral lipid accumulation, caspase activation and apoptosis in a neutrophil-like, differentiated HL-60 cell line. Clin Sci (Lond) 104: 171–179, 2003.[Medline]
24. Heimli H, Finstad HS, and Drevon CA. Necrosis and apoptosis in lymphoma cell lines exposed to eicosapentaenoic acid and antioxidants. Lipids 36: 613–621, 2001.[Web of Science][Medline]
25. Hong MP, Kim HI, Shin YK, Lee CS, Park M, and Song JH. Effects of free fatty acids on sodium currents in rat dorsal root ganglion neurons. Brain Res 1008: 81–91, 2004.[CrossRef][Web of Science][Medline]
26. Huang ZH, Hii CS, Rathjen DA, Poulos A, Murray AW, and Ferrante A. n6 and n3 polyunsaturated fatty acids stimulate translocation of protein kinase C
, -
I, -II and -
and enhance agonist-induced NADPH oxidase in macrophages. Biochem J 325: 553–557, 1997.
27. Jouaville LS, Ichas F, Holmuhamedov EL, Camacho P, and Lechleiter JD. Synchronization of calcium waves by mitochondrial substrates in Xenopus laevis oocytes. Nature 377: 438–441, 1995.[CrossRef][Medline]
28. Kahn-Kirby AH, Dantzker JLM, Apicella AJ, Schafer WR, Browse J, Bargmann CI, and Watts JL. Specific polyunsaturated fatty acids drive TRPV-dependent sensory signaling in vivo. Cell 119: 889–900, 2004.[CrossRef][Web of Science][Medline]
29. Kamishima T and Quayle JM. Mitochondrial Ca2+ uptake is important over low [Ca2+]i range in arterial smooth muscle. Am J Physiol Heart Circ Physiol 283: H2431–H2439, 2002.
30. King MP and Attardi G. Human cells lacking mtDNA: repopulation with exogenous mitochondria by complementation. Science 246: 500–503, 1989.
31. Korge P, Honda HM, and Weiss JN. Effects of fatty acids in isolated mitochondria: implications for ischemic injury and cardioprotection. Am J Physiol Heart Circ Physiol 285: H259–H269, 2003.
32. Krauss S, Zhang CY, and Lowell BB. The mitochondrial uncoupling-protein homologues. Nat Rev Mol Cell Biol 6: 248–261, 2005.[Web of Science][Medline]
33. Kuroda R, Hirata KI, Kawashima S, and Yokoyama M. Unsaturated free fatty acids inhibit Ca2+ mobilization and NO release in endothelial cells. Kobe J Med Sci 47: 211–219, 2001.[Medline]
34. Ladewig T, Kloppenburg P, Lalley PM, Zipfel WR, Webb WW, and Keller BU. Spatial profiles of store-dependent calcium release in motoneurones of the nucleus hypoglossus from newborn mouse. J Physiol 547: 775–787, 2003.
35. Lameloise N, Muzzin P, Prentki M, and Assimacopoulos-Jeannet F. Uncoupling protein 2: a possible link between fatty acid excess and impaired glucose-induced insulin secretion? Diabetes 50: 803–809, 2001.
36. Leaf A, Kang JX, Xiao YF, Billman GE, and Voskuyl RA. Experimental studies on antiarrhythmic and antiseizure effects of polyunsaturated fatty acids in excitable tissues. J Nutr Biochem 10: 440–448, 1999.[CrossRef][Web of Science][Medline]
37. Lemonnier L, Prevarskaya N, Mazurier J, Shuba Y, and Skryma R. 2-APB inhibits volume-regulated anion channels independently from intracellular calcium signaling modulation. FEBS Lett 556: 121–126, 2004.[CrossRef][Web of Science][Medline]
38. Liu J, Wu LL, Li L, Zhang L, and Song ZE. Growth-promoting effect of platelet-derived growth factor on rat cardiac myocytes. Regul Pept 127: 11–18, 2005.[CrossRef][Web of Science][Medline]
39. Liu L and Rittenhouse AR. Effects of arachidonic acid on unitary calcium currents in rat sympathetic neurons. J Physiol 525: 391–404, 2000.
40. Luo D, Broad LM, Bird GSJ, and Putney JW Jr. Signaling pathways underlying muscarinic receptor-induced [Ca2+]i oscillations in HEK293 cells. J Biol Chem 276: 5613–5621, 2001.
i41. Lupi R, Dotta F, Marselli L, Del Guerra S, Masini M, Santangelo C, Patané G, Boggi U, Piro S, Anello M, Bergamini E, Mosca F, Di Mario U, Del Prato S, and Marchetti P. Prolonged exposure to free fatty acids has cytostatic and pro-apoptotic effects on human pancreatic islets: evidence that -cell death is caspase mediated, partially dependent on ceramide pathway, and Bcl-2 regulated. Diabetes 51: 1437–1442, 2002.
42. Malli R, Freiden M, Osibow K, Zoratti C, Mayer M, Demaurex N, and Graier WF. Sustained Ca2+ transfer across mitochondria is essential for mitochondrial Ca2+ buffering, store-operated Ca2+ entry, and Ca2+ store refilling. J Biol Chem 278: 44769–44779, 2003.
43. Maruyama T, Kanaji T, Nakade S, Kanno T, and Mikoshiba K. 2APB, 2-aminoethoxydiphenyl borate, a membrane-penetrable modulator of Ins(1,4,5)P3-induced Ca2+ release. J Biochem (Tokyo) 122: 498–505, 1997.
44. Mies F, Shlyonsky V, Goolaerts A, and Sariban-Sohraby S. Modulation of epithelial Na+ channel activity by long-chain n-3 fatty acids. Am J Physiol Renal Physiol 287: F850–F855, 2004.
45. Montell C. The TRP superfamily of cation channels. Sci STKE 272: 2005.
46. Montero M, Alonso MT, Albillos A, García-Sancho J, and Alvarez J. Mitochondrial Ca2+-induced Ca2+ release mediated by the Ca2+ uniporter. Mol Biol Cell 12: 63–71, 2001.
47. Mu YM, Yanase T, Nishi Y, Tanaka A, Saito M, Jin CH, Mukasa C, Okabe T, Nomura M, Goto K, and Nawata H. Saturated FFAs, palmitic acid and stearic acid, induce apoptosis in human granulosa cells. Endocrinology 142: 3590–3597, 2001.
48. Panini SR, Yang L, Rusinol AE, Sinensky MS, Bonventre JV, and Leslie CC. Arachidonate metabolism and the signaling pathway of induction of apoptosis by oxidized LDL/oxysterol. J Lipid Res 42: 1678–1686, 2001.
49. Park K, Lee S, Elliott AC, Kim JS, and Lee JH. Swelling-induced Ca2+ release from intracellular calcium stores in rat submandibular gland acinar cells. J Membr Biol 186: 165–176, 2002.[CrossRef][Web of Science][Medline]
50. Penzo D, Petronilli V, Angelin A, Cusan C, Colonna R, Scorrano L, Pagano F, Prato M, Di Lisa F, and Bernardi P. Arachidonic acid released by phospholipase A2 activation triggers Ca2+-dependent apoptosis through the mitochondrial pathway. J Biol Chem 279: 25219–25225, 2004.
51. Petronilli V, Penzo D, Scorrano L, Bernardi P, and Di Lisa F. The mitochondrial permeability transition, release of cytochrome c and cell death. Correlation with the duration of pore openings in situ. J Biol Chem 276: 12030–12034, 2001.
52. Pfeiffer DR, Gunter TE, Eliseev R, Broekemeier KM, and Gunter KK. Release of Ca2+ from mitochondria via the saturable mechanisms and the permeability transition. IUBMB Life 52: 205–212, 2001.[Web of Science][Medline]
52a. Prakriya M and Lewis RS. Potentiation and inhibition of Ca2+ release-activated Ca2+ channels by 2-aminoethyldiphenyl borate (2-APB) occurs independently of IP3 receptors. J Physiol 536: 3–19, 2001.
53. Rahman MA, Ashton AC, Meunier FA, Davletov BA, Dolly JO, and Ushkaryov YA. Norepinephrine exocytosis stimulated by -latrotoxin requires both external and stored Ca2+ and is mediated by latrophilin, G proteins and phospholipase C. Philos Trans R Soc Lond B Biol Sci 354: 379–386, 1999.
54. Rangel LBA, Lopes AG, Lara LSM, Carvalho TLG, Silva IV, Oliveira MM, Einicker-Lamas M, Vieyra A, Nogaroli L, and Caruso-Neves C. PI-PLC is involved in the modulation of the proximal tubule Na+-ATPase by angiotensin II. Regul Pept 127: 177–182, 2005.[CrossRef][Web of Science][Medline]
55. Rizzo MT, Regazzi E, Garau D, Akard L, Dugan M, Boswell HS, Rizzoli V, and Carlo-Stella C. Induction of apoptosis by arachidonic acid in chronic myeloid leukemia cells. Cancer Res 59: 5047–5053, 1999.
56. Rizzuto R, Bernardi P, and Pozzan T. Mitochondria as all-round players of the calcium game. J Physiol 529: 37–47, 2000.
57. Rizzuto R, Duchen MR, and Pozzan T. Flirting in little space: the ER/mitochondria Ca2+ liaison. Sci STKE 215: 2004.
58. Rychkov GY, Litjens T, Roberts ML, and Barritt GJ. Arachidonic acid inhibits the store-operated Ca2+ current in rat liver cells. Biochem J 385: 551–556, 2005.[CrossRef][Web of Science][Medline]
59. Sagar PS and Das UN. Cytotoxic action of cis-unsaturated fatty acids on human cervical carcinoma (HeLa) cells in vitro. Prostaglandins Leukot Essent Fatty Acids 53: 287–299, 1995.[CrossRef][Web of Science][Medline]
60. Salathe M, Ivonnet PI, Lieb T, and Bookman RJ. Agonist-stimulated calcium decreases in ovine ciliated airway epithelial cells: role of mitochondria. J Physiol 531: 13–26, 2001.
61. Schaffer JE. Lipotoxicity: when tissues overeat. Curr Opin Lipidol 14: 281–287, 2003.[CrossRef][Web of Science][Medline]
62. Schertzer JD, Plant DR, Ryall JG, Beitzel F, Stupka N, and Lynch GS. 2-Agonist administration increases sarcoplasmic reticulum Ca2+-ATPase activity in aged rat skeletal muscle. Am J Physiol Endocrinol Metab 288: E526–E533, 2005.
63. Schönfeld P, Sayeed I, Bohnensack R, and Siemen D. Fatty acids induce chloride permeation in rat liver mitochondria by activation of the inner membrane anion channel (IMAC). J Bioenerg Biomembr 36: 241–248, 2004.[CrossRef][Web of Science][Medline]
64. Scorrano L, Penzo D, Petronilli V, Pagano F, and Bernardi P. Arachidonic acid causes cell death through the mitochondrial permeability transition. Implications for tumor necrosis factor- apoptotic signaling. J Biol Chem 276: 12035–12040, 2001.
65. Shuttleworth TJ. Arachidonic acid activates the noncapacitative entry of Ca2+ during [Ca2+]i oscillations. J Biol Chem 271: 21720–21725, 1996.
66. Siddiqui RA, Jenski LJ, Neff K, Harvey K, Kovacs RJ, and Stillwell W. Docosahexaenoic acid induces apoptosis in Jurkat cells by a protein phosphatase-mediated process. Biochim Biophys Acta 1499: 265–275, 2001.[Medline]
67. Simpson PB and Russell JT. Mitochondrial Ca2+ uptake and release influence metabotropic and ionotropic cytosolic Ca2+ responses in rat oligodendrocyte progenitors. J Physiol 508: 413–426, 1998.
68. Szabadkai G, Pitter JG, and Spät A. Cytoplasmic Ca2+ at low submicromolar concentration stimulates mitochondrial metabolism in rat luteal cells. Pflügers Arch 441: 678–685, 2001.[CrossRef][Web of Science][Medline]
69. Szabadkai G and Rizzuto R. Participation of endoplasmic reticulum and mitochondrial calcium handling in apoptosis: more than just neighborhood? FEBS Lett 567: 111–115, 2004.[CrossRef][Web of Science][Medline]
70. Terada S, Takizawa M, Yamamoto S, Ezaki O, Itakura H, and Akagawa KS. Eicosapentaenoic acid inhibits CSF-induced human monocyte survival and maturation into macrophage through the stimulation of H2O2 production. J Leukoc Biol 71: 981–986, 2002.
71. Vandecasteele G, Szabadkai G, and Rizzuto R. Mitochondrial calcium homeostasis: mechanisms and molecules. IUBMB Life 52: 213–219, 2001.[Web of Science][Medline]
72. Vaur S, Sartor P, and Dufy-Barbe L. Calcium store depletion induced by mitochondrial uncoupling in prostatic cells. Gen Physiol Biophys 19: 265–278, 2000.[Web of Science][Medline]
73. Vento R, D'Alessandro N, Giuliano M, Carabillò M, and Tesoriere G. Induction of apoptosis by arachidonic acid in human retinoblastoma Y79 cells: involvement of oxidative stress. Exp Eye Res 70: 503–517, 2000.[CrossRef][Web of Science][Medline]
74. Xiao YF, Ke Q, Chen Y, Morgan JP, and Leaf A. Inhibitory effect of n-3 fish oil fatty acids on cardiac Na+/Ca2+ exchange currents in HEK293t cells. Biochem Biophys Res Commun 321: 116–123, 2004.[CrossRef][Web of Science][Medline]
75. Zhang BX, Ma X, Yeh CK, Lifschitz MD, Zhu MX, and Katz MS. Epidermal growth factor-induced depletion of the intracellular Ca2+ store fails to activate capacitative Ca2+ entry in a human salivary cell line. J Biol Chem 277: 48165–48171, 2002.
76. Zhang BX, Yeh CK, Hymer TK, Lifschitz MD, and Katz MS. EGF inhibits muscarinic receptor-mediated calcium signaling in a human salivary cell line. Am J Physiol Cell Physiol 279: C1024–C1033, 2000.
77. Zhang BX, Zhao H, Loessberg P, and Muallem S. Activation of the plasma membrane Ca2+ pump during agonist stimulation of pancreatic acini. J Biol Chem 267: 15419–15425, 1992.
78. Zhang Z, Tang J, Tikunova S, Johnson JD, Chen Z, Qin N, Dietrich A, Stefani E, Birnbaumer L, and Zhu MX. Activation of Trp3 by inositol 1,4,5-trisphosphate receptors through displacement of inhibitory calmodulin from a common binding domain. Proc Natl Acad Sci USA 98: 3168–3173, 2001.
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