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Jiang Z, Lietz CB, Podvin S, Yoon MC, Toneff T, Hook V, O’Donoghue AJ. Differential Neuropeptidomes of Dense Core Secretory Vesicles (DCSV) Produced at Intravesicular and Extracellular pH Conditions by Proteolytic Processing. ACS Chem Neurosci 2021; 12:2385-2398. [PMID: 34153188 PMCID: PMC8267839 DOI: 10.1021/acschemneuro.1c00133] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
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Neuropeptides mediate
cell–cell signaling in the nervous
and endocrine systems. The neuropeptidome is the spectrum of peptides
generated from precursors by proteolysis within dense core secretory
vesicles (DCSV). DCSV neuropeptides and contents are released to the
extracellular environment where further processing for neuropeptide
formation may occur. To assess the DCSV proteolytic capacity for production
of neuropeptidomes at intravesicular pH 5.5 and extracellular pH 7.2,
neuropeptidomics, proteomics, and protease assays were conducted using
chromaffin granules (CG) purified from adrenal medulla. CG are an
established model of DCSV. The CG neuropeptidome consisted of 1239
unique peptides derived from 15 proneuropeptides that were colocalized
with 64 proteases. Distinct CG neuropeptidomes were generated at the
internal DCSV pH of 5.5 compared to the extracellular pH of 7.2. Class-specific
protease inhibitors differentially regulated neuropeptidome production
involving aspartic, cysteine, serine, and metallo proteases. The substrate
cleavage properties of CG proteases were assessed by multiplex substrate
profiling by mass spectrometry (MSP-MS) that uses a synthetic peptide
library containing diverse cleavage sites for endopeptidases and exopeptidases.
Parallel inhibitor-sensitive cleavages for neuropeptidome production
and peptide library proteolysis led to elucidation of six CG proteases
involved in neuropeptidome production, represented by cathepsins A,
B, C, D, and L and carboxypeptidase E (CPE). The MSP-MS profiles of
these six enzymes represented the majority of CG proteolytic cleavages
utilized for neuropeptidome production. These findings provide new
insight into the DCSV proteolytic system for production of distinct
neuropeptidomes at the internal CG pH of 5.5 and at the extracellular
pH of 7.2.
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Affiliation(s)
- Zhenze Jiang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States
| | - Christopher B. Lietz
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
| | - Sonia Podvin
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
| | - Michael C. Yoon
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
| | - Thomas Toneff
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
| | - Vivian Hook
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
- Department of Neuroscience and Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States
| | - Anthony J. O’Donoghue
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, United States
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Javadov S, Chapa-Dubocq X, Makarov V. Different approaches to modeling analysis of mitochondrial swelling. Mitochondrion 2017; 38:58-70. [PMID: 28802667 DOI: 10.1016/j.mito.2017.08.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/21/2017] [Accepted: 08/08/2017] [Indexed: 12/11/2022]
Abstract
Mitochondria are critical players involved in both cell life and death through multiple pathways. Structural integrity, metabolism and function of mitochondria are regulated by matrix volume due to physiological changes of ion homeostasis in cellular cytoplasm and mitochondria. Ca2+ and K+ presumably play a critical role in physiological and pathological swelling of mitochondria when increased uptake (influx)/decreased release (efflux) of these ions enhances osmotic pressure accompanied by high water accumulation in the matrix. Changes in the matrix volume in the physiological range have a stimulatory effect on electron transfer chain and oxidative phosphorylation to satisfy metabolic requirements of the cell. However, excessive matrix swelling associated with the sustained opening of mitochondrial permeability transition pores (PTP) and other PTP-independent mechanisms compromises mitochondrial function and integrity leading to cell death. The mechanisms of transition from reversible (physiological) to irreversible (pathological) swelling of mitochondria remain unknown. Mitochondrial swelling is involved in the pathogenesis of many human diseases such as neurodegenerative and cardiovascular diseases. Therefore, modeling analysis of the swelling process is important for understanding the mechanisms of cell dysfunction. This review attempts to describe the role of mitochondrial swelling in cell life and death and the main mechanisms involved in the maintenance of ion homeostasis and swelling. The review also summarizes and discusses different kinetic models and approaches that can be useful for the development of new models for better simulation and prediction of in vivo mitochondrial swelling.
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Affiliation(s)
- Sabzali Javadov
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA.
| | - Xavier Chapa-Dubocq
- Department of Physiology, School of Medicine, University of Puerto Rico, San Juan, PR, USA
| | - Vladimir Makarov
- Department of Physics, Rio Piedras Campus, University of Puerto Rico, San Juan, PR, USA
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Clark AJ, Coury EL, Meilhac AM, Petty HR. WO3/Pt nanoparticles are NADPH oxidase biomimetics that mimic effector cells in vitro and in vivo. NANOTECHNOLOGY 2016; 27:065101. [PMID: 26683660 DOI: 10.1088/0957-4484/27/6/065101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
To provide a means of delivering an artificial immune effector cell-like attack on tumor cells, we report the tumoricidal ability of inorganic WO3/Pt nanoparticles that mimic a leukocyte's functional abilities. These nanoparticles route electrons from organic structures and electron carriers to form hydroxyl radicals within tumor cells. During visible light exposure, WO3/Pt nanoparticles manufacture hydroxyl radicals, degrade organic compounds, use NADPH, trigger lipid peroxidation, promote lysosomal membrane disruption, promote the loss of reduced glutathione, and activate apoptosis. In a model of advanced breast cancer metastasis to the eye's anterior chamber, we show that WO3/Pt nanoparticles prolong the survival of 4T1 tumor-bearing Balb/c mice. This new generation of inorganic photosensitizers do not photobleach, and therefore should provide an important therapeutic advance in photodynamic therapy. As biomimetic nanoparticles destroy targeted cells, they may be useful in treating ocular and other forms of cancer.
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Affiliation(s)
- Andrea J Clark
- Department of Ophthalmology and Visual Sciences, 1000 Wall Street, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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Beck A, Fleig A, Penner R, Peinelt C. Regulation of endogenous and heterologous Ca²⁺ release-activated Ca²⁺ currents by pH. Cell Calcium 2014; 56:235-43. [PMID: 25168908 DOI: 10.1016/j.ceca.2014.07.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 07/16/2014] [Accepted: 07/22/2014] [Indexed: 10/24/2022]
Abstract
Deviations from physiological pH (∼pH 7.2) as well as altered Ca(2+) signaling play important roles in immune disease and cancer. One of the most ubiquitous pathways for cellular Ca(2+) influx is the store-operated Ca(2+) entry (SOCE) or Ca(2+) release-activated Ca(2+) current (ICRAC), which is activated upon depletion of intracellular Ca(2+) stores. We here show that extracellular and intracellular changes in pH regulate both endogenous ICRAC in Jurkat T lymphocytes and RBL2H3 cells, and heterologous ICRAC in HEK293 cells expressing the molecular components STIM1/2 and Orai1/2/3 (CRACM1/2/3). We find that external acidification suppresses, and alkalization facilitates IP3-induced ICRAC. In the absence of IP3, external alkalization did not elicit endogenous ICRAC but was able to activate heterologous ICRAC in HEK293 cells expressing Orai1/2/3 and STIM1 or STIM2. Similarly, internal acidification reduced IP3-induced activation of endogenous and heterologous ICRAC, while alkalization accelerated its activation kinetics without affecting overall current amplitudes. Mutation of two aspartate residues to uncharged alanine amino acids (D110/112A) in the first extracellular loop of Orai1 significantly attenuated both the inhibition of ICRAC by external acidic pH as well as its facilitation by alkaline conditions. We conclude that intra- and extracellular pH differentially regulates ICRAC. While intracellular pH might affect aggregation and/or binding of STIM to Orai, external pH seems to modulate ICRAC through its channel pore, which in Orai1 is partially mediated by residues D110 and D112.
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Affiliation(s)
- Andreas Beck
- Queen's Center for Biomedical Research, Laboratory of Cell and Molecular Signaling, The Queen's Medical Center, Honolulu, HI 96813, United States; John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, United States; Department of Pharmacology and Toxicology, ZHMB, Saarland University, D-66421 Homburg, Germany
| | - Andrea Fleig
- Queen's Center for Biomedical Research, Laboratory of Cell and Molecular Signaling, The Queen's Medical Center, Honolulu, HI 96813, United States; John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, United States
| | - Reinhold Penner
- Queen's Center for Biomedical Research, Laboratory of Cell and Molecular Signaling, The Queen's Medical Center, Honolulu, HI 96813, United States; John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, United States.
| | - Christine Peinelt
- Queen's Center for Biomedical Research, Laboratory of Cell and Molecular Signaling, The Queen's Medical Center, Honolulu, HI 96813, United States; John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, United States; Department of Biophysics, Saarland University, ZHMB, 66421 Homburg, Germany.
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5
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Szczepanowska J, Malinska D, Wieckowski MR, Duszynski J. Effect of mtDNA point mutations on cellular bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1740-6. [PMID: 22406627 DOI: 10.1016/j.bbabio.2012.02.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/13/2012] [Accepted: 02/14/2012] [Indexed: 10/28/2022]
Abstract
This overview discusses the results of research on the effects of most frequent mtDNA point mutations on cellular bioenergetics. Thirteen proteins coded by mtDNA are crucial for oxidative phosphorylation, 11 of them constitute key components of the respiratory chain complexes I, III and IV and 2 of mitochondrial ATP synthase. Moreover, pathogenic point mutations in mitochondrial tRNAs and rRNAs generate abnormal synthesis of the mtDNA coded proteins. Thus, pathogenic point mutations in mtDNA usually disturb the level of key parameter of the oxidative phosphorylation, i.e. the electric potential on the inner mitochondrial membrane (Δψ), and in a consequence calcium signalling and mitochondrial dynamics in the cell. Mitochondrial generation of reactive oxygen species is also modified in the mutated cells. The results obtained with cultured cells and describing biochemical consequences of mtDNA point mutations are full of contradictions. Still they help elucidate the biochemical basis of pathologies and provide a valuable tool for finding remedies in the future. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
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Affiliation(s)
- Joanna Szczepanowska
- Department of Biochemsitry, Nencki Institute of Experimental Biology, Warsaw, Poland
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Kim B, Takeuchi A, Koga O, Hikida M, Matsuoka S. Pivotal role of mitochondrial Na⁺₋Ca²⁺ exchange in antigen receptor mediated Ca²⁺ signalling in DT40 and A20 B lymphocytes. J Physiol 2011; 590:459-74. [PMID: 22155933 DOI: 10.1113/jphysiol.2011.222927] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) increases upon activation of antigen-receptor in lymphocytes. Mitochondria have been suggested to regulate the [Ca(2+)](i) response, but the molecular mechanisms and the roles are poorly understood. To clarify them, we carried out a combination study of mathematical simulations and knockout or knockdown of NCLX, a gene candidate for the mitochondrial Na(+)-Ca(2+) exchanger (NCX(mit)), in B lymphocytes. A mathematical model of Ca(2+) dynamics in B lymphocytes demonstrated that NCX(mit) inhibition reduces basal Ca(2+) content of endoplasmic reticulum (ER) and suppresses B-cell antigen receptor (BCR)-mediated [Ca(2+)](i) rise. The predictions were validated in DT40 B lymphocytes of heterozygous NCLX knockout (NCLX(+/-)). In NCLX(+/-) cells, mitochondrial Ca(2+) efflux via NCX(mit) was strongly decelerated, suggesting NCLX is a gene responsible for NCX(mit) in B lymphocytes. Consistent with the predictions, ER Ca(2+) content declined and [Ca(2+)](i) hardly rose upon BCR activation in NCLX(+/-) cells. ER Ca(2+) uptake was reduced to ∼58% of the wild-type (WT), while it was comparable to WT when mitochondrial respiration was disturbed. Essentially the same results were obtained by a pharmacological inhibition or knockdown of NCLX by siRNA in A20 B lymphocytes. Unexpectedly, ER Ca(2+) leak was augmented and co-localization of mitochondria with ER was lower in NCLX(+/-) and NCLX silenced cells. Taken together, we concluded that NCLX is a key Ca(2+) provider to ER, and that NCLX-mediated Ca(2+) recycling between mitochondria and ER is pivotal in B cell responses to antigen.
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Affiliation(s)
- Bongju Kim
- Center for Innovation in Immunoregulative Technology and Therapeutics, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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Ryu SY, Beutner G, Dirksen RT, Kinnally KW, Sheu SS. Mitochondrial ryanodine receptors and other mitochondrial Ca2+ permeable channels. FEBS Lett 2010; 584:1948-55. [PMID: 20096690 DOI: 10.1016/j.febslet.2010.01.032] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2009] [Revised: 01/11/2010] [Accepted: 01/18/2010] [Indexed: 01/06/2023]
Abstract
Ca(2+) channels that underlie mitochondrial Ca(2+) transport first reported decades ago have now just recently been precisely characterized electrophysiologically. Numerous data indicate that mitochondrial Ca(2+) uptake via these channels regulates multiple intracellular processes by shaping cytosolic and mitochondrial Ca(2+) transients, as well as altering the cellular metabolic and redox state. On the other hand, mitochondrial Ca(2+) overload also initiates a cascade of events that leads to cell death. Thus, characterization of mitochondrial Ca(2+) channels is central to a comprehensive understanding of cell signaling. Here, we discuss recent progresses in the biophysical and electrophysiological characterization of several distinct mitochondrial Ca(2+) channels.
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Affiliation(s)
- Shin-Young Ryu
- Department of Pharmacology and Physiology, and Mitochondrial Research Innovation Group, University of Rochester Medical Center, Rochester, NY 14642, USA
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8
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Clark AJ, Diamond M, Elfline M, Petty HR. Calicum microdomains form within neutrophils at the neutrophil-tumor cell synapse: role in antibody-dependent target cell apoptosis. Cancer Immunol Immunother 2009; 59:149-59. [PMID: 19593564 DOI: 10.1007/s00262-009-0735-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 06/29/2009] [Indexed: 01/03/2023]
Abstract
Ca(2+) messages are broadly important in cellular signal transduction. In immune cells, Ca(2+) signaling is an essential step in many forms of activation. Neutrophil-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) is one form of leukocyte activation that plays an important role in tumor cell killing in vitro and in patient care. Using fluorescence methodologies, we found that neutrophils exhibit Ca(2+) signals during ADCC directed against breast fibrosarcoma cells. Importantly, these signals were localized to Ca(2+) microdomains at the neutrophil-to-tumor cell interface where they display dynamic features such as movement, fusion, and fission. These signals were blocked by the intracellular Ca(2+) buffer BAPTA. At the neutrophil-tumor cell synapse, the neutrophil's cytoplasm was enriched in STIM1, a crucial mediator of Ca(2+) signaling, whereas the Ca(2+)-binding proteins calbindin and parvalbumin were not affected. Our findings suggest that Ca(2+) microdomains are due to an active signaling process. As Ca(2+) signals within neutrophils were necessary for specific tumor cell apoptosis, a central role of microdomains in leukocyte-mediated tumor cell destruction is indicated.
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Affiliation(s)
- Andrea J Clark
- Department of Ophthalmology and Visual Sciences, The University of Michigan Medical School, 1000 Wall Street, Ann Arbor, MI 48105, USA
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9
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Czyź A, Brutkowski W, Fronk J, Duszyński J, Zabłocki K. Tunicamycin desensitizes store-operated Ca2+ entry to ATP and mitochondrial potential. Biochem Biophys Res Commun 2009; 381:176-80. [PMID: 19338771 DOI: 10.1016/j.bbrc.2009.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 02/05/2009] [Indexed: 01/11/2023]
Abstract
Tunicamycin effect on thapsigargin-induced store-operated calcium entry was investigated. Ca2+ influx was stimulated by 50% upon exposure of Jurkat cells to tunicamycin. Moreover, tunicamycin efficiently prevented the inhibition of store-operated calcium entry caused by dissipation of mitochondrial membrane potential. Protective action of tunicamycin on store-operated Ca2+ entry was also partially preserved in Jurkat cells depleted of ATP, while Ca2+ entry into ATP-deprived cells grown in tunicamycin-free medium was almost completely inhibited. Tunicamycin-evoked changes in cellular Ca2+ fluxes coincided with decreased glycosylation of STIM1 protein. Although the latter observation is correlative and needs additional confirmation it may suggest that deglycosylation of STIM1 protein deprives store-operated calcium entry system of an important regulatory mechanism. This study suggests a novel mechanism of modulation of the activity of store-operated calcium channels in lymphoidal cells.
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Affiliation(s)
- Aneta Czyź
- The Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
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10
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Ardón F, Rodríguez-Miranda E, Beltrán C, Hernández-Cruz A, Darszon A. Mitochondrial inhibitors activate influx of external Ca2+ in sea urchin sperm. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:15-24. [DOI: 10.1016/j.bbabio.2008.10.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 09/16/2008] [Accepted: 10/09/2008] [Indexed: 01/01/2023]
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Role of STIM1 in regulation of store-operated Ca2+ influx in pheochromocytoma cells. Cell Mol Neurobiol 2008; 29:193-202. [PMID: 18807171 DOI: 10.1007/s10571-008-9311-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2007] [Accepted: 08/27/2008] [Indexed: 01/08/2023]
Abstract
Changes in the local environment such as pH (acidosis/alkalosis), temperature (hypothermia/hyperthermia), and agonist (glutamate) can adversely affect neuronal function, and are important factors in clinical situations such as anesthesia and intensive care. Regulation of intracellular Ca2+ ([Ca2+](i)) is key to neuronal function. Stromal interaction molecule (STIM1) has been recently recognized to trigger store-operated Ca2+ entry (SOCE), an important component of [Ca2+](i) regulation. Using differentiated, fura-2 loaded rat pheochromocytoma (PC12) cells transfected with small interference RNA for STIM1 (or vehicle), we examined the role of STIM1 in SOCE sensitivity to temperature, pH, and glutamate. SOCE was triggered following endoplasmic reticulum depletion. Cells were washed and exposed to altered pH (6.0-8.0), altered temperature (34-40 degrees C), or to glutamate. In non-transfected cells, SOCE was inhibited by acidosis or hypothermia, but increased with alkalosis and hyperthermia. Increasing glutamate concentrations progressively stimulated SOCE. STIM1 siRNA decreased SOCE at normal temperature and pH, and substantially decreased sensitivity to acidosis and hypothermia, eliminating the concentration-dependence to glutamate. Sensitivity of SOCE to these environmental parameters was less altered by decreased extracellular Ca2+ alone (with STIM1 intact). We conclude that STIM1 mediates exquisite susceptibility of SOCE to pH, temperature, and glutamate: factors that can adversely affect neuronal function under pathological conditions.
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Kozieł R, Zabłocki K, Duszyński J. Calcium signals are affected by ciprofloxacin as a consequence of reduction of mitochondrial DNA content in Jurkat cells. Antimicrob Agents Chemother 2006; 50:1664-71. [PMID: 16641433 PMCID: PMC1472211 DOI: 10.1128/aac.50.5.1664-1671.2006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effects of ciprofloxacin on mitochondrial DNA (mtDNA) content, oxygen consumption, mitochondrial membrane potential, cellular ATP formation, and capacitative Ca(2+) entry into Jurkat cells were investigated. In cells incubated for several days with 25 mug/ml ciprofloxacin, a 60% reduction of mtDNA content, inhibition of the respiratory chain, and a significant decrease in mitochondrial membrane potential were observed. These changes led to a decrease in the calcium buffering capacity of mitochondria which, in turn, resulted in a gradual inhibition of the capacitative Ca(2+) entry. On days 4, 7, and 11 of incubation with ciprofloxacin, the initial rates of Ca(2+) entry were reduced by 33%, 50%, and 50%, respectively. Ciprofloxacin caused a transient decrease in the cellular capability for ATP formation. In cells incubated for 15 min with glucose, pyruvate, and glutamine as exogenous fuel, ciprofloxacin reduced ATP content by 16% and 35% on days 4 and 7, respectively, of incubation with the drug. However, on day 11 of incubation with ciprofloxacin, a recovery of cellular ATP formation was observed. In conclusion, long-term exposure of Jurkat cells to ciprofloxacin at a concentration of 25 mug/ml seriously affects cellular energy metabolism and calcium homeostasis.
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Affiliation(s)
- Rafał Kozieł
- Nencki Institute of Experimental Biology, Pasteura 3, 02-093 Warsaw, Poland
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13
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Duszyński J, Kozieł R, Brutkowski W, Szczepanowska J, Zabłocki K. The regulatory role of mitochondria in capacitative calcium entry. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:380-7. [PMID: 16777055 DOI: 10.1016/j.bbabio.2006.04.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 04/13/2006] [Accepted: 04/20/2006] [Indexed: 11/19/2022]
Abstract
Capacitative regulation of calcium entry is a major mechanism of Ca2+ influx into electrically non-excitable cells, but it also operates in some excitable ones. It participates in the refilling of intracellular calcium stores and in the generation of Ca2+ signals in excited cells. The mechanism which couples depletion of intracellular calcium stores located in the endoplasmic reticulum with opening of store-operated calcium channels in the plasma membrane is not clearly understood. Mitochondria located in close proximity to Ca2+ channels are exposed to high Ca2+ concentration, and therefore, they are able to accumulate this cation effectively. This decreases local Ca2+ concentration and thereby affects calcium-dependent processes, such as depletion and refilling of the intracellular calcium stores and opening of the store-operated channels. Finally, mitochondria modulate the intensity and the duration of calcium signals induced by extracellular stimuli. Ca2+ uptake by mitochondria requires these organelles to be in the energized state. On the other hand, Ca2+ flux into mitochondria stimulates energy metabolism. To sum up, mitochondria couple cellular metabolism with calcium homeostasis and signaling.
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Affiliation(s)
- Jerzy Duszyński
- Nencki Institute of Experimental Biology, 3 Pasteur Str., 02-093 Warsaw, Poland
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Núñez L, Valero RA, Senovilla L, Sanz-Blasco S, García-Sancho J, Villalobos C. Cell proliferation depends on mitochondrial Ca2+ uptake: inhibition by salicylate. J Physiol 2005; 571:57-73. [PMID: 16339178 PMCID: PMC1805645 DOI: 10.1113/jphysiol.2005.100586] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a ubiquitous Ca2+ influx pathway involved in control of multiple cellular and physiological processes including cell proliferation. Recent evidence has shown that SOCE depends critically on mitochondrial sinking of entering Ca2+ to avoid Ca2+-dependent inactivation. Thus, a role of mitochondria in control of cell proliferation could be anticipated. We show here that activation of SOCE induces cytosolic high [Ca2+] domains that are large enough to be sensed and avidly taken up by a pool of nearby mitochondria. Prevention of mitochondrial clearance of the entering Ca2+ inhibited both SOCE and cell proliferation in several cell types including Jurkat and human colon cancer cells. In addition, we find that therapeutic concentrations of salicylate, the major metabolite of aspirin, depolarize partially mitochondria and inhibit mitochondrial Ca2+ uptake, as revealed by mitochondrial Ca2+ measurements with targeted aequorins. This salicylate-induced inhibition of mitochondrial Ca2+ sinking prevented SOCE and impaired cell growth of Jurkat and human colon cancer cells. Finally, direct blockade of SOCE by the pyrazole derivative BTP-2 was sufficient to arrest cell growth. Taken together, our results reveal that cell proliferation depends critically on mitochondrial Ca2+ uptake and suggest that inhibition of tumour cell proliferation by salicylate may be due to interference with mitochondrial Ca2+ uptake, which is essential for sustaining SOCE. This novel mechanism may contribute to explaining the reported anti-proliferative and anti-tumoral actions of aspirin and dietary salicylates.
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Affiliation(s)
- Lucía Núñez
- Instituto de Biología y Genética Molecular (IBGM), c/Sanz y Forés s/n. 47003-Valladolid, Spain
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