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Shapovalov G, Ritaine A, Bidaux G, Slomianny C, Borowiec AS, Gordienko D, Bultynck G, Skryma R, Prevarskaya N. Organelle membrane derived patches: reshaping classical methods for new targets. Sci Rep 2017; 7:14082. [PMID: 29074990 PMCID: PMC5658434 DOI: 10.1038/s41598-017-13968-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 10/04/2017] [Indexed: 12/12/2022] Open
Abstract
Intracellular ion channels are involved in multiple signaling processes, including such crucial ones as regulation of cellular motility and fate. With 95% of the cellular membrane belonging to intracellular organelles, it is hard to overestimate the importance of intracellular ion channels. Multiple studies have been performed on these channels over the years, however, a unified approach allowing not only to characterize their activity but also to study their regulation by partner proteins, analogous to the patch clamp “golden standard”, is lacking. Here, we present a universal approach that combines the extraction of intracellular membrane fractions with the preparation of patchable substrates that allows to characterize these channels in endogenous protein environment and to study their regulation by partner proteins. We validate this method by characterizing activity of multiple intracellular ion channels localized to different organelles and by providing detailed electrophysiological characterization of the regulation of IP3R activity by endogenous Bcl-2. Thus, after synthesis and reshaping of the well-established approaches, organelle membrane derived patch clamp provides the means to assess ion channels from arbitrary cellular membranes at the single channel level.
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Affiliation(s)
- George Shapovalov
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France
| | - Abigaël Ritaine
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France
| | - Gabriel Bidaux
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France.,Laboratoire INSERM U1060, CarMeN Laboratory, Claude Bernard Lyon 1 University, 8, avenue Rockfeller, F-69373, Lyon, France
| | - Christian Slomianny
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France
| | - Anne-Sophie Borowiec
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France.,Laboratoire INSERM U1060, CarMeN Laboratory, Claude Bernard Lyon 1 University, 8, avenue Rockfeller, F-69373, Lyon, France
| | - Dmitri Gordienko
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Herestraat 49, BE-3000, Leuven, Belgium
| | - Roman Skryma
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France.,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France
| | - Natalia Prevarskaya
- Inserm U1003, Equipe Labellisée par la Ligue Nationale Contre le Cancer, Université de Sciences et Technologies de Lille (USTL), F-59655, Villeneuve d'Ascq, France. .,Laboratory of Excellence, Ion Channels Science and Therapeutics; Université Lille I Sciences et Technologies, Villeneuve d'Ascq, France.
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2
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Kinnally KW, Campo ML, Tedeschi H. Mitochondrial channel activity studied by patch-clamping mitoplasts. J Bioenerg Biomembr 1989; 21:497-506. [PMID: 2478535 DOI: 10.1007/bf00762521] [Citation(s) in RCA: 162] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Patch-clamping mitoplasts, we have observed a complex pattern of conductance transitions. This report discusses primarily the 45, 120-150, 350, and 1,000 pS transitions.
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Affiliation(s)
- K W Kinnally
- Department of Biological Sciences, State University of New York, Albany, 12222
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3
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Rule CJ, Behm CA, Bygrave FL. Aberrant energy-linked reactions in mitochondria isolated from the livers of rats infected with the liver fluke Fasciola hepatica. Biochem J 1989; 260:517-23. [PMID: 2527493 PMCID: PMC1138698 DOI: 10.1042/bj2600517] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The respiratory properties of mitochondria isolated from the livers of rats infected with the parasite Fasciola hepatica were examined. Oligomycin-sensitive ATPase activity was also examined during the acute stage (2-4 weeks post-infection). At 2,4 and 6 weeks post-infection, mitochondrial respiration in vitro (supported by site I and site II substrates) was completely uncoupled. Limited respiratory control had returned by 11 weeks post-infection, but complete recovery was not observed even at 21 weeks post-infection. At 4 weeks post-infection, uncoupled respiration (from all three energy-conserving sites) was also markedly attenuated (to the greatest extent with NADH-linked substrate). Except for pyruvate-supported respiration, this attenuation was not apparent at any other stage of the infection. The attenuation of pyruvate-supported respiration declined, but was still present, at 6 weeks post-infection. In addition to these perturbations in mitochondrial respiratory properties, mitochondrial ATPase activity at 4 weeks post-infection was insensitive to oligomycin, indicating a change in the structural integrity of the ATPase complex.
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Affiliation(s)
- C J Rule
- Department of Biochemistry, Faculty of Science, Australian National University, Canberra
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4
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Sandri G, Siagri M, Panfili E. Influence of Ca2+ on the isolation from rat brain mitochondria of a fraction enriched of boundary membrane contact sites. Cell Calcium 1988; 9:159-65. [PMID: 3191526 DOI: 10.1016/0143-4160(88)90020-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Data have been obtained suggesting that the complex porin-hexokinase of brain mitochondria may be related to the contact sites between the outer and inner membrane. In the attempt to isolate from brain mitochondria the inner and outer membranes and the boundary membrane contacts, a procedure was developed based on swelling and shrinking of the organelles, followed by sonication and reverse discontinuous density gradient centrifugation. Three fractions were obtained by this technique, which were identified by measuring the relative specific activities of marker enzymes, namely succinate-cytochrome c reductase; NADH-cytochrome c reductase (rotenone insensitive); hexokinase and glutathione transferase, for the inner and outer membranes and contact sites, respectively. The fraction which contains the contact sites is characterized by the highest specific activity of hexokinase and glutathione transferase and by the highest calcium binding capacity; physiological concentrations of this cation produces a sharper separation of this fraction. Results indicate that both the porin-hexokinase gating system of the outer membrane and the calcium transporting complex of the inner membrane are present in the fraction which contains the contact sites.
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Affiliation(s)
- G Sandri
- Dipartimento di Biochimica, Università degli Studi, Trieste, Italy
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5
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Burcham JM, Giometti CS, Tollaksen SL, Peraino C. Comparison of rat and mouse ornithine aminotransferase with respect to molecular properties and regulation of synthesis. Arch Biochem Biophys 1988; 262:501-7. [PMID: 3364978 DOI: 10.1016/0003-9861(88)90401-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A comparative study of the synthesis patterns and molecular properties of mouse and rat ornithine aminotransferase (OAT) was conducted. The two enzymes were found to be very similar with respect to catalytic properties, two-dimensional electrophoresis patterns of tryptic digests, amino acid compositions, and antibody cross-reactivity. In vitro translation assays for OAT synthesis on free polysomes isolated from livers at different times of day showed similar circadian fluctuations in OAT synthesis for both species. However, hybridization measurements revealed no circadian changes in the levels of hybridizable OAT mRNA in these livers. These results demonstrate that the circadian cycling of OAT synthesis is regulated at the level of translation in both the rat and the mouse.
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Affiliation(s)
- J M Burcham
- Division of Biological and Medical Research, Argonne National Laboratory, Illinois 60439-4833
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6
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Power JH, Jones ME, Barr HA, Nicholas TE. Analysis of pulmonary phospholipid compartments in the unanesthetized rat during prolonged periods of hyperpnea. Exp Lung Res 1986; 11:105-28. [PMID: 3757932 DOI: 10.3109/01902148609063274] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We exposed rats to 4% CO2-10% O2-86% N2 for 24 h before infusing with 20 microCi kg-1 (methyl-3H)choline chloride. They were then exposed for periods up to 48 h, at which times their lungs were degassed and lavaged. The lavage fluid was divided into a tubular myelin-rich (PLalv-1) and a tubular myelin-poor (PLalv-2) fraction. Lamellar body (lb) and microsomal (m) fractions were prepared from the lung tissue and the amount of phospholipid (PL) was determined in each of the 4 fractions. Specific activity (sp.act.) curves were constructed for both control and hyperpneic groups. Exposure to the gas doubled both tidal volume and frequency of breathing. Total PLalv, PLlb and PLm were all markedly elevated, which, when taken in conjunction with the changes in sp.act. in these fractions, suggests that the rate of surfactant PL synthesis was increased within 24 h. The shapes of the sp.act. curves suggest precursor-product relationships between PLlb and PLalv-1 and between PLalv-1 and PLalv-2. However, when we applied analysis based on the Zilversmit steady-state equation, instead of the expected straight line, we found a marked clockwise hysteresis that did not return to the origin. Whereas this may reflect PLalv being supplied from 2 tissue pools, we argue that, in fact, we are not dealing with classic compartmental precursor-product relationships.
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7
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Storm H, van Hardeveld C. Effect of thyroid hormone on intracellular Ca2+ mobilization by noradrenaline and vasopressin in relation to glycogenolysis in rat liver. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 846:275-85. [PMID: 2992606 DOI: 10.1016/0167-4889(85)90075-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The relation between Ca2+ efflux, Ca2+ mobilization from mitochondria and glycogenolysis was studied in perfused euthyroid and hypothyroid rat livers stimulated by Ca2+-mobilizing hormones. Ca2+ efflux, induced by noradrenaline (1 microM) in the absence or presence of DL-propranolol (10 microM) from livers perfused with medium containing a low concentration of Ca2+ (approx. 24 microM), was decreased by more than 50% in hypothyroidism. This correlated with an equal decrease of the fractional mobilization of mitochondrial Ca2+, which could account for 65% of the difference between the net amounts of Ca2+ expelled from the euthyroid and hypothyroid livers. With vasopressin (10 nM) similar results were found, suggesting that hypothyroidism has a general effect on mobilization of internal Ca2+. In normal Ca2+ medium (1300 microM), however, the effect of vasopressin on net Ca2+ fluxes and phosphorylase activation was not impaired in hypothyroidism, indicating that Ca2+ mobilization from the mitochondria in this case plays a minor role in phosphorylase activation. The alpha 1-adrenergic responses of Ca2+ efflux, phosphorylase activation and glucose output, glucose-6-phosphatase activity and oxygen consumption in hypothyroid rat liver were completely restored by in vivo T3 injections (0.5 micrograms per 100 g body weight, daily during 3 days). Perfusion with T3 (100 pM) during 19 min did not influence hypothyroid rat liver oxygen consumption and alpha 1-receptor-mediated Ca2+ efflux. However, this in vitro T3 treatment showed a completely recovered alpha 1-adrenergic response of phosphorylase and a partly restored glucose-6-phosphatase activity and glucose output. The results indicate that thyroid hormones may control alpha 1-adrenergic stimulation of glycogenolysis by at least two mechanisms, i.e., a long-term action on Ca2+ mobilization, and a short-term action on separate stages of the glycogenolytic process.
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8
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Fournier N, Gallice P, Crevat A, Murisasco A, Ducet G, Elsen R. Action on mitochondrial calcium metabolism of an ionophorous compound isolated from uremic plasma or normal urine. Artif Organs 1985; 9:22-7. [PMID: 3994549 DOI: 10.1111/j.1525-1594.1985.tb04342.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
An ionophorous compound that is one of the uremic middle molecules is able to inhibit the mitochondrial storage of calcium. Its active concentration is equivalent to that found in uremic plasma. This result can explain the diminution of phosphate calcium granules observed in mitochondria from uremic children. Moreover, this phenomenon may be involved in the calcium pool decrease observed in chronic renal insufficiency.
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9
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Epping RJ, Taylor WM, Bygrave FL. Characterisation of Ca2+ transport activity by white adipose tissue mitochondria. FEBS Lett 1983; 158:21-6. [PMID: 6190683 DOI: 10.1016/0014-5793(83)80668-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Ca2+ transport in mitochondria isolated from rat white adipocytes has been examined and many of the properties found to be similar to those reported for mitochondria isolated from rat liver. Ca2+ transport is ruthenium red-sensitive (Ki approximately 5 pmol . mg protein-1), the affinity for free Ca2+ is high (Km approximately 3.3 microM) and the Vmax is 135 nmol Ca2+ . min-1 . mg protein-1 at 4 degrees C with 0.2 mM Pi present. Ca2+ transport is stimulated by increasing the medium [Pi], and is inhibited when ATP or Mg2+ is added to the incubation system and in contrast to brown adipocyte mitochondria, Ca2+ efflux is not promoted by Na+. White adipocyte mitochondria may play a rôle in the regulation of total cell calcium in this tissue.
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11
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Reinhart PH, Taylor WM, Bygrave FL. A procedure for the rapid preparation of mitochondria from rat liver. Biochem J 1982; 204:731-5. [PMID: 7126163 PMCID: PMC1158413 DOI: 10.1042/bj2040731] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A technique for the rapid preparation of mitochondria from rat liver is described. Tissue fractionation is performed by a single centrifugation step with a discontinuous Percoll density gradient. Total preparation times of 5--6 min are achieved by using this method. The mitochondrial fraction obtained is relatively free of contaminating organelles, as judged by marker-enzyme activity determinations. Mitochondria isolated by Percoll-density-gradient centrifugation differ from mitochondria obtained by differential centrifugation [Taylor, Prpić, Exton & Bygrave (1980) Biochem. J. 188, 443--450] in that the former exhibit a higher acceptor control ratio and a higher calcium content. Values obtained for the protonmotive force are not significantly different between the two preparations. The technique described may be widely applicable for studies requiring the rapid preparation of functionally intact and relatively uncontaminated mitochondria.
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12
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Ruthenium red-sensitive and Ruthenium Red-insensitive release of calcium by mitochondria isolated from rat liver and from rat heart. Cell Calcium 1981. [DOI: 10.1016/0143-4160(81)90001-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Prpić V, Bygrave FL. Maturation in liver mitochondria of Ruthenium Red-sensitive calcium-ion-transport activity and the influence of glucagon administration in vivo and in utero. Biochem J 1981; 196:207-16. [PMID: 6171266 PMCID: PMC1162984 DOI: 10.1042/bj1960207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The maturation of Ca(2+) transport in mitochondria isolated from rat liver was examined, from 5 days before birth. The mitochondria used were isolated from liver homogenates by centrifugation at 22000g-min. Ca(2+) transport by mitochondria isolated from foetal liver is energy-dependent and Ruthenium Red-sensitive. The transmembrane pH gradient in these mitochondria is higher by about 7mV and the membrane potential lower by about 20mV than in adult mitochondria. The inclusion of 2mm-P(i) in the incubation medium enhances the protonmotive force by approx. 30mV. The rate of Ca(2+) influx in foetal mitochondria measured in buffered KCl plus succinate is low until about 2-3h after birth, when it increases to about 60% of adult values; approx. 24h later it has reached near-adult values. Higher rates of Ca(2+) influx are observed in the presence of 2mm-P(i); 3-5 days before birth the rates are about one-third of adult values and decline slightly as birth approaches. By 2-3h post partum they have reached adult values. The inclusion of 12.5mum-MgATP with the P(i) stimulates further the initial rate of Ca(2+) influx in foetal mitochondria. The rates observed are constant over the prenatal period examined and are 50-60% of those observed in adult mitochondria. Mitochondria isolated from foetal livers 4-5 days before birth retain the accumulated Ca(2+) for about 50min in the presence of 2mm-P(i). In the period 2 days before birth to birth, this ability is largely lost, but by 2-3h after birth Ca(2+) retention is similar to that of adult mitochondria. The presence of 12.5mum-MgATP progressively enhances the Ca(2+) retention time as development proceeds until 2-3h after birth, when it becomes less sensitive to added MgATP. Glucagon administration to older foetuses in utero enhances both the rate of mitochondrial Ca(2+) influx assayed in the presence of 2mm-P(i) and the time for which mitochondria retain accumulated Ca(2+) in the presence of 12.5mum-MgATP and 2mm-P(i). Its administration to neonatal animals leads to an increase in mitochondrial Ca(2+) retention similar to that seen in adult mitochondria. The data provide evidence that the Ruthenium Red-sensitive Ca(2+) transporter is potentially as active in foetal mitochondria 5 days before birth as it is in adult mitochondria. They also show that foetal mitochondria have an ability to retain accumulated Ca(2+) reminiscent of mitochondria from tumour cells and from hormone-challenged rat liver.
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Reinhart PH, Bygrave FL. Glucagon stimulation of ruthenium red-insensitive calcium ion transport in developing rat liver. Biochem J 1981; 194:541-9. [PMID: 6171260 PMCID: PMC1162778 DOI: 10.1042/bj1940541] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The maturation of glucagon-stimulated Ruthenium Red-insensitive Ca2+-transport activity was determined in livers of rats ranging in age from 5 days preterm to 10 weeks of adult life. Previous indications are that this activity is confined to vesicles derived mainly from the endoplasmic reticulum. Perinatal-rat liver contains near-adult values of Ruthenium Red-insensitive Ca2+-transport activity, and exhibits large transient increases in the rate of this activity at two stages of development, immediately after birth, and at 2-5 days after birth. The administration of glucagon to foetal rats, at developmental stages after 19.5 days of gestation (2.5 days before birth), results in a large stable increase (greater than 100%) of Ca2+-transport activity in a subsequently isolated 'heavy' microsomal fraction. That this fraction was enriched in vesicles derived from the rough endoplasmic reticulum was indicated by both an electron-microscopic examination and a marker-enzyme analysis of the subcellular fractions. The administration of glucagon into newborn animals only hours old does not enhance further the initial rate of Ca2+-transport activity, and from day 1 to 10 weeks after birth the administration of the hormone results in the moderate enhancement of Ca2+ transport. Experiments with cyclic AMP and inhibitors of phosphodiesterase activity suggest that cyclic AMP plays a key role in the enhancement by glucagon of Ruthenium Red-insensitive Ca2+ transport, and arguments are presented that this transport system has an important metabolic role in the redistribution of intracellular Ca2+ in liver tissue.
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Reinhart PH, Taylor WM, Bygrave FL. Trifluoperazine, an inhibitor of calmodulin action, antagonises phenylephrine-induced metabolic responses and mitochondrial calcium fluxes in liver. FEBS Lett 1980; 120:71-4. [PMID: 7439392 DOI: 10.1016/0014-5793(80)81049-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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May ME, Mancusi VJ, Aftring RP, Buse MG. Effects of diabetes on oxidative decarboxylation of branched-chain keto acids. THE AMERICAN JOURNAL OF PHYSIOLOGY 1980; 239:E215-22. [PMID: 7435556 DOI: 10.1152/ajpendo.1980.239.3.e215] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Oxidative decarboxylation is the first irreversible step in the degradation of leucine. The effect of streptozotocin diabetes on this reaction was studied in cell-free rat liver preparations, using [1-14C]alpha-ketoisocaproate as substrate. Diabetes increased the branched-chain ketoacid dehydrogenase (BCKD) activity (per g liver or per mg protein) of homogenates, but the ratios of homogenate BCKD activity to other mitochondrial markers remained unchanged. A cytosolic branched-chain ketoacid decarboxylase activity (15-22% of homogenate activity), which did not require NAD, CoA, or NADP, was also increased in diabetics. Insulin treatment of diabetics normalized enzyme activity in all fractions. The apparent Km of BCKD in homogenates was 43-45 microM; diabetes increased the apparent Vmax from 165 nmol x min-1 x g tissue-1 to 260 nmol x min-1 x g-1. In contrast, the Km for cytosolic alpha-ketoisocaproate decarboxylation was 270 microM in controls, and diabetes resulted in both a lower Km (210 microM) and a higher Vmax. Adrenalectomy did not affect activity in homogenates from controls, but partially reversed the diabetes-associated increase. Glucagon pretreatment of controls did not affect activity. In summary, distinct mitochondrial and cytosolic enzymes decarboxylate alpha-ketoisocaproate in liver. The increased hepatic capacity of diabetic rats to degrade the carbon skeleton of leucine is attributed mainly to a relative increase in mitochondrial mass.
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Prpić V, Bygrave F. On the inter-relationship between glucagon action, the oxidation-reduction state of pyridine nucleotides, and calcium retention by rat liver mitochondria. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43721-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Taylor WM, Prpić V, Exton JH, Bygrave FL. Stable changes to calcium fluxes in mitochondria isolated from rat livers perfused with alpha-adrenergic agonists and with glucagon. Biochem J 1980; 188:443-50. [PMID: 7396872 PMCID: PMC1161887 DOI: 10.1042/bj1880443] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mitochondria isolated from rat liver after a short-term perfusion with the alpha-adrenergic agonist phenylephrine or with glucagon exhibited enhanced rates of uptake of Ca2+ and prolonged retention of Ca2+ in the presence of 4mm-P(i). The effect of Ca2+ retention was apparent after perfusion with phenylephrine for only 1min and was maximal after 7min of treatment. The changes induced by glucagon, although similar, were less rapid. Adrenaline caused similar changes to phenylephrine and its effects were blocked by the alpha-adrenergic antagonist phenoxybenzamine, but not by the beta-antagonist propranolol. The Ca2+ content of the isolated mitochondria decreased by 30% 1min after the onset of perfusion with phenylephrine; by 6min it had begun to return to the original value which was reached at 10min. A similar loss in calcium content was induced by glucagon but the changes were not as great and occurred more slowly. Mitochondria from phenylephrine-treated livers exhibited decreased rates of Ca2+ efflux induced by addition of 2mm-EGTA, a 50% increase in the contents of ADP and total adenine nucleotides, a small increase in the transmembrane pH gradient, and a reduced rate of oxaloacetate-induced NADPH oxidation. This study thus shows that stimulation of liver by alpha-adrenergic agonists, like that by glucagon, induces within minutes a stable modification of mitochondria leading to alterations in the Ca2+-translocation cycle (increased Ca2+ uptake and retention) and alterations in mitochondrial energy-linked reactions.
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20
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Taylor WM, Bygrave FL, Blackmore PF, Exton JH. Stable enhancement of ruthenium red-insensitive calcium transport in an endoplasmic reticulum-rich fraction following the exposure of isolated rat liver cells to glucagon. FEBS Lett 1979; 104:31-4. [PMID: 225203 DOI: 10.1016/0014-5793(79)81079-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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21
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Studies on alpha-adrenergic activation of hepatic glucose output. The role of mitochondrial calcium release in alpha-adrenergic activation of phosphorylase in perfused rat liver. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50266-0] [Citation(s) in RCA: 142] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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22
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Blackmore PF, Dehaye JP, Strickland WG, Exton JH. alpha-Adrenergic mobilization of hepatic mitochondrial calcium. FEBS Lett 1979; 100:117-20. [PMID: 437092 DOI: 10.1016/0014-5793(79)81144-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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23
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Abstract
The efflux of Ca2+ from rat heart mitochondria has been examined by using Ruthenium Red to inhibit active uptake after predetermined loadings with Ca2+. The efflux is proportional to the internal Ca2+ load; it is increased by Na+ applied when the mitochondria are respiring and this effect is inhibited by oligomycin. The efflux of Ca2+ is diminished by ATP and by ADP, with the latter the more effective. Both active uptake and efflux of Ca2+ are slowed by bongkrekic acid; this action has a time lag. The lower efflux found with the nucleotides and with bongkrekic acid seems to correspond to the more condensed state seen in the electron microscope when these agents are applied [Stoner & Sirak (1973) J. Cell Biol. 56, 51-64, 65-73]. The results are discussed in relation to the less-permeable state being contingent upon nucleotide binding to the membrane.
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Prpić V, Spencer TL, Bygrave FL. Stable enhancement of calcium retention in mitochondria isolated from rat liver after the administration of glucagon to the intact animal. Biochem J 1978; 176:705-14. [PMID: 747647 PMCID: PMC1186292 DOI: 10.1042/bj1760705] [Citation(s) in RCA: 85] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
1. Mitochondria isolated from rat liver by centrifugation of the homogenate in buffered iso-osmotic sucrose at between 4000 and 8000g-min, 1h after the administration in vivo of 30mug of glucagon/100g body wt., retain Ca(2+) for over 45min after its addition at 100nmol/mg of mitochondrial protein in the presence of 2mm-P(i). In similar experiments, but after the administration of saline (0.9% NaCl) in place of glucagon, Ca(2+) is retained for 6-8min. The ability of glucagon to enhance Ca(2+) retention is completely prevented by co-administration of 4.2mg of puromycin/100g body wt. 2. The resting rate of respiration after Ca(2+) accumulation by mitochondria from glucagon-treated rats remains low by contrast with that from saline-treated rats. Respiration in the latter mitochondria increased markedly after the Ca(2+) accumulation, reflecting the uncoupling action of the ion. 3. Concomitant with the enhanced retention of Ca(2+) and low rates of resting respiration by mitochondria from glucagon-treated rats was an increased ability to retain endogenous adenine nucleotides. 4. An investigation of properties of mitochondria known to influence Ca(2+) transport revealed a significantly higher concentration of adenine nucleotides but not of P(i) in those from glucagon-treated rats. The membrane potential remained unchanged, but the transmembrane pH gradient increased by approx. 10mV, indicating increased alkalinity of the matrix space. 5. Depletion of endogenous adenine nucleotides by P(i) treatment in mitochondria from both glucagon-treated and saline-treated rats led to a marked diminution in ability to retain Ca(2+). The activity of the adenine nucleotide translocase was unaffected by glucagon treatment of rats in vivo. 6. Although the data are consistent with the argument that the Ca(2+)-translocation cycle in rat liver mitochondria is a target for glucagon action in vivo, they do not permit conclusions to be drawn about the molecular mechanisms involved in the glucagon-induced alteration to this cycle.
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Smith RL, Bygrave FL. Enrichment of ruthenium red-sensitive Ca2+ transport in a population of heavy mitochondria isolated from flight-muscle of Lucilia cuprina. Further evidence for its heterogeneous distribution in the inner mitochondrial membrane. FEBS Lett 1978; 95:303-6. [PMID: 720623 DOI: 10.1016/0014-5793(78)81016-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Bygrave FL, Tranter CJ. The subcellular location, maturation and response to increased plasma glucagon of ruthenium red-insensitive calcium-ion transport in rat liver. Biochem J 1978; 174:1021-30. [PMID: 215118 PMCID: PMC1186008 DOI: 10.1042/bj1741021] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1. The subcellular distribution and maturation of Ruthenium Red-insensitive Ca(2+) transport activity were determined in livers of rats ranging in age from 3 days pre-term to 10 weeks of adult life and compared with those of glucose 6-phosphatase, 5'-nucleotidase and Ruthenium Red-sensitive Ca(2+) transport. Initial rates of Ruthenium Red-insensitive Ca(2+) transport were highest in those fractions enriched in glucose 6-phosphatase, i.e. the microsomal fraction; this fraction was devoid of Ruthenium Red-sensitive Ca(2+) transport activity. Although the heaviest fraction (nuclear) contained significant amounts of 5'-nucleotidase activity it was devoid of Ruthenium Red-insensitive Ca(2+) transport activity. 2. Foetal rat liver contain minimal amounts of Ruthenium Red-insensitive Ca(2+) transport activity, glucose 6-phosphatase and 5'-nucleotidase activities. These begin to be expressed concomitantly soon after birth; Ruthenium Red-insensitive Ca(2+) transport is maximal by 3 to 4 days and remains so for up to at least 10 weeks of adult life. Glucose 6-phosphatase also reaches a peak at 3-4 days, but then rapidly decreases to approach adult values. Maximal activity of 5'-nucleotidase in the microsomal and nuclear fractions is seen about 4-6 days after birth; this enzyme activity remains increased for up to about 10 days and then falls, but not as rapidly as glucose 6-phosphatase. It is tentatively suggested that the bulk of the Ruthenium Red-insensitive Ca(2+) transport is attributable to the system derived from the endoplasmic reticulum. 3. Administration of glucagon to adult rats enhances by 2-3-fold the initial rate of Ruthenium Red-insensitive Ca(2+) transport in the intermediate but not the microsomal fraction. The hormone-induced effect is fully suppressed by co-administration of puromycin, is dose-dependent with half-maximal response at approx. 1mug of glucagon/100g body wt. and time-dependent exhibiting a half-maximal response about 1h after administration of the hormone. 4. Ruthenium Red-insensitive Ca(2+) transport in the post-mitochondrial fraction of foetal liver also responds to the administration in situ of glucagon. The response, which also is prevented by co-administration of puromycin, is maximal in those foetuses nearing term. The suggestion is made that these effects of the hormone on Ruthenium Red-insensitive Ca(2+) transport are an integral part of the physiological network in the liver cell.
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Bygrave FL, Smith RL. Inability of tributyltin-induced chloride/hydroxyl exchange to stimulate calcium transport in mitochondria isolated from flight muscle of the sheep blowfly Lucilia cuprina. Biochem J 1978; 174:1075-7. [PMID: 728076 PMCID: PMC1186016 DOI: 10.1042/bj1741075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tributyltin in the concentration range 1-4mum failed to stimulate Ca(2+) transport by Lucilia flight-muscle mitochondria in a medium containing KCl and respiratory substrate but devoid of P(i), despite its promotion of a rapid Cl(-)/OH(-) exchange. When 2mm-P(i) was present, concentrations of tributyltin greater than 1mum inhibited the initial rate of Ca(2+) transport and induced efflux of the ion from the mitochondria in Cl(-)- or NO(3) (-)-containing media. Lower concentrations had little effect. Oligomycin added at up to 10mug/mg of mitochondrial protein had no effect on Ca(2+) transport. By contrast, approx. 0.3mum-tributyltin completely inhibited respiration supported by alpha-glycerophosphate in either the presence or absence of added ADP. The data suggest that tributyltin can inhibit Ca(2+) transport in Lucilia flight-muscle mitochondria other than by facilitating a Cl(-)/OH(-) exchange or producing an oligomycin-like effect.
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