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Seedhom MO, Dersh D, Holly J, Pavon-Eternod M, Wei J, Angel M, Shores L, David A, Santos J, Hickman H, Yewdell JW. Paradoxical imbalance between activated lymphocyte protein synthesis capacity and rapid division rate. eLife 2024; 12:RP89015. [PMID: 38512721 PMCID: PMC10957176 DOI: 10.7554/elife.89015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024] Open
Abstract
Rapid lymphocyte cell division places enormous demands on the protein synthesis machinery. Flow cytometric measurement of puromycylated ribosome-associated nascent chains after treating cells or mice with translation initiation inhibitors reveals that ribosomes in resting lymphocytes in vitro and in vivo elongate at typical rates for mammalian cells. Intriguingly, elongation rates can be increased up to 30% by activation in vivo or fever temperature in vitro. Resting and activated lymphocytes possess abundant monosome populations, most of which actively translate in vivo, while in vitro, nearly all can be stalled prior to activation. Quantitating lymphocyte protein mass and ribosome count reveals a paradoxically high ratio of cellular protein to ribosomes insufficient to support their rapid in vivo division, suggesting that the activated lymphocyte proteome in vivo may be generated in an unusual manner. Our findings demonstrate the importance of a global understanding of protein synthesis in lymphocytes and other rapidly dividing immune cells.
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Affiliation(s)
- Mina O Seedhom
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Devin Dersh
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Jaroslav Holly
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | | | - Jiajie Wei
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Matthew Angel
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Lucas Shores
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Alexandre David
- CNRS UMR-5203; INSERM U661; UM1; UM2, Institut de Génomique FonctionnelleMontpellierFrance
| | - Jefferson Santos
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Heather Hickman
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
| | - Jonathan W Yewdell
- National Institute of Allergy and Infectious DiseasesBethesdaUnited States
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2
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Singh V, Johansson P, Lin YL, Hammarsten O, Westerlund F. Shining light on single-strand lesions caused by the chemotherapy drug bleomycin. DNA Repair (Amst) 2021; 105:103153. [PMID: 34119948 DOI: 10.1016/j.dnarep.2021.103153] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/17/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022]
Abstract
Quantification of the DNA damage induced by chemotherapy in patient cells may aid in personalization of the dose used. However, assays to evaluate individual patient response to chemotherapy are not available today. Here, we present an assay that quantifies single-stranded lesions caused by the chemotherapeutic drug Bleomycin (BLM) in peripheral blood mononuclear cells (PBMCs) isolated from healthy individuals. We use base excision repair (BER) enzymes to process the DNA damage induced by BLM and then extend the processed sites with fluorescent nucleotides using a DNA polymerase. The fluorescent patches are quantified on single DNA molecules using fluorescence microscopy. Using the assay, we observe a significant variation in the in vitro induced BLM damage and its repair for different individuals. Treatment of the cells with the BER inhibitor CRT0044876 leads to a lower level of repair of BLM-induced damage, indicating the ability of the assay to detect a compromised DNA repair in patients. Overall, the data suggest that our assay could be used to sensitively detect the variation in BLM-induced DNA damage and repair in patients and can potentially be able to aid in personalizing patient doses.
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Affiliation(s)
- Vandana Singh
- Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden; Laboratory of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden.
| | - Pegah Johansson
- Laboratory of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Yii-Lih Lin
- Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Ola Hammarsten
- Laboratory of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Fredrik Westerlund
- Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
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3
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Geissler R, Golbik RP, Behrens SE. The DEAD-box helicase DDX3 supports the assembly of functional 80S ribosomes. Nucleic Acids Res 2012; 40:4998-5011. [PMID: 22323517 PMCID: PMC3367175 DOI: 10.1093/nar/gks070] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The DEAD-box helicase DDX3 has suggested functions in innate immunity, mRNA translocation and translation, and it participates in the propagation of assorted viruses. Exploring initially the role of DDX3 in the life cycle of hepatitis C virus, we observed the protein to be involved in translation directed by different viral internal ribosomal entry sites. Extension of these studies revealed a general supportive role of DDX3 in translation initiation. DDX3 was found to interact in an RNA-independent manner with defined components of the translational pre-initiation complex and to specifically associate with newly assembling 80S ribosomes. DDX3 knock down and in vitro reconstitution experiments revealed a significant function of the protein in the formation of 80S translation initiation complexes. Our study implies that DDX3 assists the 60S subunit joining process to assemble functional 80S ribosomes.
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Affiliation(s)
- Rene Geissler
- Institute of Biochemistry and Biotechnology, Faculty of Life Sciences (NFI), Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany
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4
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Yamashita R, Saito T, Satoh S, Aoki K, Kaburagi Y, Sekihara H. Effects of dehydroepiandrosterone on gluconeogenic enzymes and glucose uptake in human hepatoma cell line, HepG2. Endocr J 2005; 52:727-33. [PMID: 16410665 DOI: 10.1507/endocrj.52.727] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Dehydroepiandrosterone (DHEA), the most abundant human adrenal steroid, improves insulin sensitivity and obesity in human and model animals. In a previous study, we reported that orally administered DHEA suppresses the elevated activities of hepatic gluconeogenic enzymes like glucose-6-phosphatase (G6Pase) in C57BL/KsJ-db/db mice. However, the molecular mechanisms by which DHEA ameliorates insulin resistance are not clearly understood. In the present study, we cultured the human hepatoma cell line HepG2 with DHEA and measured the enzyme activity and protein expression of G6Pase to investigate the direct effect of DHEA on glucose metabolism in hepatocytes. DHEA significantly suppressed both the activity and protein expression of G6Pase. Moreover, DHEA decreased the gene expression of G6Pase and phosphoenolpyruvate carboxykinase, both of which were maximal at 1 microM DHEA, whereas the mRNA level of glucose-6-phosphate translocase was unchanged. Furthermore, DHEA enhanced 2-deoxyglucose uptake, although its effect was much smaller than that of insulin. These results suggest that DHEA may act at multiple steps in the regulation of glucose metabolism in the liver.
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Affiliation(s)
- Ryo Yamashita
- Department of Endocrinology and Metabolism, Yokohama City University Graduate School of Medicine
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5
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Yamazaki T, Sasaki E, Kakinuma C, Yano T, Miura S, Ezaki O. Increased Very Low Density Lipoprotein Secretion and Gonadal Fat Mass in Mice Overexpressing Liver DGAT1. J Biol Chem 2005; 280:21506-14. [PMID: 15797871 DOI: 10.1074/jbc.m412989200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acyl-CoA:diacylglycerol acyltransferases (DGATs) catalyze the last step in triglyceride (TG) synthesis. The genes for two DGAT enzymes, DGAT1 and DGAT2, have been identified. To examine the roles of liver DGAT1 and DGAT2 in TG synthesis and very low density lipoprotein (VLDL) secretion, liver DGAT1- and DGAT2-overexpressing mice were created by adenovirus-mediated gene transfection. DGAT1-overexpressing mice had markedly increased DGAT activity in the presence of the permeabilizing agent alamethicin. This suggests that DGAT1 possesses latent DGAT activity on the lumen of the endoplasmic reticulum. DGAT1-overexpressing mice showed increased VLDL secretion, resulting in increased gonadal (epididymal or parametrial) fat mass but not subcutaneous fat mass. The VLDL-mediated increase in gonadal fat mass might be due to the 4-fold greater expression of the VLDL receptor protein in gonadal fat than in subcutaneous fat. DGAT2-overexpressing mice had increased liver TG content, but VLDL secretion was not affected. These results indicate that DGAT1 but not DGAT2 has a role in VLDL synthesis and that increased plasma VLDL concentrations may promote obesity, whereas increased DGAT2 activity has a role in steatosis.
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Affiliation(s)
- Tomomi Yamazaki
- Division of Clinical Nutrition, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8636, Japan
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6
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Vila-Sanjurjo A, Schuwirth BS, Hau CW, Cate JHD. Structural basis for the control of translation initiation during stress. Nat Struct Mol Biol 2004; 11:1054-9. [PMID: 15502846 DOI: 10.1038/nsmb850] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 09/28/2004] [Indexed: 11/08/2022]
Abstract
During environmental stress, organisms limit protein synthesis by storing inactive ribosomes that are rapidly reactivated when conditions improve. Here we present structural and biochemical data showing that protein Y, an Escherichia coli stress protein, fills the tRNA- and mRNA-binding channel of the small ribosomal subunit to stabilize intact ribosomes. Protein Y inhibits translation initiation during cold shock but not at normal temperatures. Furthermore, protein Y competes with conserved translation initiation factors that, in bacteria, are required for ribosomal subunit dissociation. The mechanism used by protein Y to reduce translation initiation during stress and quickly release ribosomes for renewed translation initiation may therefore occur widely in nature.
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Affiliation(s)
- Antón Vila-Sanjurjo
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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7
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Guionie O, Clottes E, Stafford K, Burchell A. Identification and characterisation of a new human glucose-6-phosphatase isoform. FEBS Lett 2003; 551:159-64. [PMID: 12965222 DOI: 10.1016/s0014-5793(03)00903-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The liver endoplasmic reticulum glucose-6-phosphatase catalytic subunit (G6PC1) catalyses glucose 6-phosphate hydrolysis during gluconeogenesis and glycogenolysis. The highest glucose-6-phosphatase activities are found in the liver and the kidney; there have been many reports of glucose 6-phosphate hydrolysis in other tissues. We cloned a new G6Pase isoform (G6PC3) from human brain encoded by a six-exon gene (chromosome 17q21). G6PC3 protein was able to hydrolyse glucose 6-phosphate in transfected Chinese hamster ovary cells. The optimal pH for glucose 6-phosphate hydrolysis was lower and the K(m) higher relative to G6PC1. G6PC3 preferentially hydrolyzed other substrates including pNPP and 2-deoxy-glucose-6-phosphate compared to the liver enzyme.
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Affiliation(s)
- Olivier Guionie
- Ninewells Hospital and Medical School, University of Dundee, DD1 9SY Dundee, UK
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8
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Clottes E, Middleditch C, Burchell A. Rat liver glucose-6-phosphatase system: light scattering and chemical characterization. Arch Biochem Biophys 2002; 408:33-41. [PMID: 12485600 DOI: 10.1016/s0003-9861(02)00523-4] [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: 10/27/2022]
Abstract
Glucose-6-phosphatase is a multicomponent system located in the endoplasmic reticulum, involving both a catalytic subunit (G6PC) and several substrate and product carriers. The glucose-6-phosphate carrier is called G6PT1. Using light scattering, we determined K(D) values for phosphate and glucose transport in rat liver microsomes (45 and 33mM, respectively), G6PT1 K(D) being too low to be estimated by this technique. We provide evidence that phosphate transport may be carried out by an allosteric multisubunit translocase or by two distinct proteins. Using chemical modifications by sulfhydryl reagents with different solubility properties, we conclude that in G6PT1, one thiol group important for activity is facing the cytosol and could be Cys(121) or Cys(362). Moreover, a different glucose-6-phosphate translocase, representing 20% of total glucose-6-phosphate transport and insensitive to N-ethylmaleimide modification, could coexist with liver G6PT1. In the G6PC protein, an accessible thiol group is facing the cytosol and, according to structural predictions, could be Cys(284).
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Affiliation(s)
- Eric Clottes
- Laboratoire Inter-universitaire des Activités Physiques et Sportives, Faculté de Médecine, 28 Place Henri Dunant, 63001, Clermont-Ferrand Cedex, France
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9
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Foster JD, Nordlie RC. The biochemistry and molecular biology of the glucose-6-phosphatase system. Exp Biol Med (Maywood) 2002; 227:601-8. [PMID: 12192101 DOI: 10.1177/153537020222700807] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Progress has continued to be made over the past 4 years in our understanding of the glucose-6-phosphatase (G6Pase) system. The gene for a second component of the system, the putative glucose-6-P transporter (G6PT), was cloned, and mutations in this gene were found in patients diagnosed with glycogen storage disease type 1b. The functional characterization of this putative G6PT has been initiated, and the relationship between substrate transport via the G6PT and catalysis by the system's catalytic subunit continues to be explored. A lively debate over the feasibility of various aspects of the two proposed models of the G6Pase system persists, and the functional/structural relationships of the individual components of the system remain a hot topic of interest in G6Pase research. New evidence supportive of physiologic roles for the biosynthetic functions of the G6Pase system in vivo also has emerged over the past 4 years.
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Affiliation(s)
- James D Foster
- Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58203, USA.
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10
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Peng J, Chen PY, Marchase RB, Prestwich GD. Preparation and use of a photoactivatable glucose-6-phosphate analogue. Bioorg Med Chem Lett 2000; 10:535-9. [PMID: 10741548 DOI: 10.1016/s0960-894x(00)00043-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
A benzophenone-containing derivative of glucose-6-phosphate, 6-[(3-([2,3-3H2]-p-benzoyl dihydrocinnamidoylpropyl-1-oxy)phosphoryl]-D-glucopyranose ([3H]BZDC-Glc-6-P) was synthesized and employed to photoaffinity label proteins on intact rat liver microsomes. The use of a non-photoactivatable, UV-transparent desoxy analogue of BZDC, named p-benzyldihydrocinnamoyl (BnDC), is introduced as a general method to achieve competition when hydrophilic ligands are modified with hydrophobic photophores.
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Affiliation(s)
- J Peng
- Department of Medicinal Chemistry, The University of Utah, Salt Lake City 84112-5820, USA
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11
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Abstract
Glycogen storage disease type 1b is caused by a deficiency in a glucose 6-phosphate transporter (G6PT) that translocates glucose 6-phosphate from the cytoplasm to the endoplasmic reticulum lumen where the active site of glucose 6-phosphatase is situated. Using amino- and carboxyl-terminal tagged G6PT, we demonstrate that proteolytic digestion of intact microsomes resulted in the cleavage of both tags, indicating that both termini of G6PT face the cytoplasm. This is consistent with ten and twelve transmembrane domain models for G6PT predicted by hydropathy analyses. A region of G6PT corresponding to amino acid residues 50-71, which constitute a transmembrane segment in the twelve-domain model, are situated in a 51-residue luminal loop in the ten-domain model. To determine which of these two models is correct, we generated two G6PT mutants, T53N and S55N, that created a potential Asn-linked glycosylation site at residues 53-55 (N53SS) or 55-57 (N55QS), respectively. N53SS or N55QS would be glycosylated only if it is situated in a luminal loop larger than 33 residues as predicted by the ten-domain model. Whereas wild-type G6PT is not a glycoprotein, both T53N and S55N mutants are glycosylated, strongly supporting the ten-helical model for G6PT.
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Affiliation(s)
- C J Pan
- Heritable Disorders Branch, NICHHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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12
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D'Santos CS, Clarke JH, Divecha N. Phospholipid signalling in the nucleus. Een DAG uit het leven van de inositide signalering in de nucleus. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1436:201-32. [PMID: 9838115 DOI: 10.1016/s0005-2760(98)00146-5] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Diverse methodologies, ranging from activity measurements in various nuclear subfractions to electron microscopy, have been used to demonstrate and establish that many of the key lipids and enzymes responsible for the metabolism of inositol lipids are resident in nuclei. PtdIns(4)P, PtdIns(4,5)P2 and PtdOH are all present in nuclei, as well as the corresponding enzyme activities required to synthesise and metabolise these compounds. In addition other non-inositol containing phospholipids such as phosphatidylcholine constitute a significant percentage of the total nuclear phospholipid content. We feel that it is pertinent to include this lipid in our discussion as it provides an alternative source of 1, 2-diacylglycerol (DAG) in addition to the hydrolysis of PtdIns(4, 5)P2. We discuss at length data related to the sources and possible consequences of nuclear DAG production as this lipid appears to be increasingly central to a number of general physiological functions. Data relating to the existence of alternative pathways of inositol phospholipid synthesis, the role of 3-phosphorylated inositol lipids and lipid compartmentalisation and transport are reviewed. The field has also expanded to a point where we can now also begin to address what role these lipids play in cellular proliferation and differentiation and hopefully provide avenues for further research.
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Affiliation(s)
- C S D'Santos
- The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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13
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Clottes E, Burchell A. Three thiol groups are important for the activity of the liver microsomal glucose-6-phosphatase system. Unusual behavior of one thiol located in the glucose-6-phosphate translocase. J Biol Chem 1998; 273:19391-7. [PMID: 9677356 DOI: 10.1074/jbc.273.31.19391] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Liver microsomal glucose-6-phosphatase (Glc-6-Pase) is a multicomponent system involving both substrate and product carriers and a catalytic subunit. We have investigated the inhibitory effect of N-ethylmaleimide (NEM), a rather specific sulfhydryl reagent, on rat liver Glc-6-Pase activity. Three thiol groups are important for Glc-6-Pase system activity. Two of them are located in the glucose-6-phosphate (Glc-6-P) translocase, and one is located in the catalytic subunit. The other transporters (phosphate and glucose) are not affected by NEM treatment. The NEM alkylation of the catalytic subunit sulfhydryl residue is prevented by preincubating the disrupted microsomes with saturating concentrations of substrate or product. This suggests either that the modified cysteine is located in the protein active site or that substrate binding hides the thiol group via a conformational change in the enzyme structure. Two other thiols important for the Glc-6-Pase system activity are located in the Glc-6-P translocase and are more reactive than the one located in the catalytic subunit. The study of the NEM inhibition of the translocase has provided evidence of the existence of two distinct areas in the protein that can behave independently, with conformational changes occurring during Glc-6-P binding to the transporter. The recent cloning of a human putative Glc-6-P carrier exhibiting homologies with bacterial phosphoester transporters, such as Escherichia coli UhpT (a Glc-6-P translocase), is compatible with the fact that two cysteine residues are important for the bacterial Glc-6-P transport.
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Affiliation(s)
- E Clottes
- Department of Obstetrics and Gynaecology, Ninewells Hospital and Medical School, Dundee University, Dundee, DD1 9SY, Scotland
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14
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Jedlicka P, Panniers R. Mechanism of activation of protein synthesis initiation in mitogen-stimulated T lymphocytes. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98458-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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15
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Morris DR, White MW. Growth-regulation of the cellular levels and expression of the mRNA molecules coding for ornithine decarboxylase and S-adenosylmethionine decarboxylase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1988; 250:241-52. [PMID: 3076322 DOI: 10.1007/978-1-4684-5637-0_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- D R Morris
- Department of Biochemistry, University of Washington, Seattle
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16
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Hölttä E, Hovi T. Polyamine depletion results in impairment of polyribosome formation and protein synthesis before onset of DNA synthesis in mitogen-activated human lymphocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 152:229-37. [PMID: 3930244 DOI: 10.1111/j.1432-1033.1985.tb09188.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lymphocytes, exposed to mitogens in culture, show enhanced protein and RNA synthesis before the onset of DNA synthesis. Inhibition by DL-alpha-difluoromethylornithine of polyamine synthesis in phytohaemagglutinin-activated human lymphocytes resulted in a suppression of protein synthesis, which was evident before the initiation of DNA synthesis. The mitogen-induced increase in the incorporation of [3H]thymidine into DNA was subsequently inhibited in parallel with the activity of thymidine kinase in the polyamine-depleted cells. Ultraviolet absorbance measurement of the ribosomes after sucrose gradient centrifugation revealed a suppression of polyribosome formation that coincided with the decrease in the rate of protein synthesis. The disturbance in the polysomal profiles did not appear to be due to a shortage of mRNA, since the synthesis of poly(A)-rich mRNA was reduced less than that of rRNA after inhibiting polyamine synthesis. Entry of both the pre-existing and newly synthesized ribosomal subunits into polysomal structures was found to be impaired. These results thus suggest an important role for polyamines in the initiation step of protein synthesis.
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17
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Degen JL, Neubauer MG, Degen SJ, Seyfried CE, Morris DR. Regulation of protein synthesis in mitogen-activated bovine lymphocytes. Analysis of actin-specific and total mRNA accumulation and utilization. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44150-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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18
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Engelhardt M. Quantitative analysis of mRNA synthesis during early cortisol action on rat thymocytes: restricted size of a possible hormone response. Mol Cell Endocrinol 1983; 29:309-33. [PMID: 6840393 DOI: 10.1016/0303-7207(83)90020-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Complete inhibition of cortisol-induced pycnosis was seen by actinomycin D and cycloheximide only when added during the initial period of hormone action. This phenomenon, being a characteristic of steroid hormone effects in general, is often taken as indirect evidence for early steroid-induced mRNA synthesis. The lack of direct evidence for this theory has been tested for significance. Approximately 133 newly synthesized mRNA molecules were found to accumulate in the cytoplasm/min/cell, suggesting an average synthesis rate for individual mRNA species of about 1 copy/h/cell. Electrophoretic fractionation of double labelled RNA failed to reveal any changes of the isotope ratio of single fractions during the first 15-45 min of cortisol action, within an experimental error corresponding to +/- 2- +/- 20 molecules/cell. Possible effects of cortisol are thus restricted to changes in the range of constitutive mRNA synthesis rates. In contrast, the RNA labelling pattern was differentially changed after 45 min treatment with 10(-5) M cycloheximide.
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19
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MacDonald RG, Cidlowski JA. Glucocorticoids inhibit precursor incorporation into protein in splenic lymphocytes by stimulating protein degradation and expanding intracellular amino acid pools. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 717:236-47. [PMID: 7115767 DOI: 10.1016/0304-4165(82)90175-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In the presence of tracer concentrations of extracellular leucine (5 microM), treatment of rat splenic lymphocyte suspensions in vitro with 1 microM dexamethasone for 2.5-4 h caused a 30-35% inhibition of [3H]leucine incorporation into protein. As the extracellular leucine concentration was raised to 5mM, this inhibition was progressively reduced to 0-12%. This phenomenon correlated with a marked dependence on extracellular leucine concentration of the dexamethasone-dependent enlargement of free intracellular leucine pools in splenic lymphocytes: a 123% increase in pool size with tracer extracellular leucine; a 10% increase with 5 mM leucine. Varying extracellular leucine had no effect on: (1) nuclear [3H]dexamethasone binding by the cells; (2) the concentration of dexamethasone needed for half-maximal inhibiton of [3H]leucine incorporation; (3) the time course of onset and maximal expression of the hormonal inhibition of [3H]leucine incorporation; or (4) the magnitude of dexamethasone-dependent inhibition of [3H]uridine incorporation into RNA by these cells. There was no detectable effect of dexamethasone on uptake and retention of [3H]leucine by the cells regardless of the extracellular leucine concentration. Treatment of splenic lymphocytes for 4 h in vitro with 1 microM dexamethasone caused a small shift of ribosomes from larger aggregate polysomes to smaller forms. Thus, glucocorticoid-induced inhibition of amino aicd incorporation in splenic lymphocytes is a multicomponent response, of which an actual decrease in protein synthesis is only a small part. Enlargement of free intracellular amino acid pools, probably resulting from increased protein degradation, is the major contributing factor to the hormonal inhibition of amino acid incorporation.
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20
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Doggett DL, Chang MP, Makinodan T, Strehler BL. Cellular and molecular aspects of immune system aging. Mol Cell Biochem 1981; 37:137-56. [PMID: 7024781 DOI: 10.1007/bf02354883] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We begin with a brief discussion of the importance and advantages of immune studies to the problem of aging. This is followed by a short over-view of immune system aging at the systemic level. The major portion of the article is a review of observation, both at the cellular and molecular level, of changes in aging immune cells, with sections on intercellular communication, membrane phenomena, cyclic nucleotides, and molecular genetic changes.
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Cooper H, Braverman R. Close correlation between initiator methionyl-tRNA level and rate of protein synthesis during human lymphocyte growth cycle. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68985-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Cooper HL, Braverman R. Protein synthesis in resting and growth-stimulated human peripheral lymphocytes. Evidence for regulation by a non-messenger RNA. Exp Cell Res 1980; 127:351-9. [PMID: 6155283 DOI: 10.1016/0014-4827(80)90440-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Berger SL, Birkenmeier CS. Inhibition of intractable nucleases with ribonucleoside--vanadyl complexes: isolation of messenger ribonucleic acid from resting lymphocytes. Biochemistry 1979; 18:5143-9. [PMID: 497174 DOI: 10.1021/bi00590a018] [Citation(s) in RCA: 381] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Wettenhall RE, Slobbe A. Rate-limiting factors for lymphocyte protein synthesis. Ribosome commitment and the capacity of lymphocyte cell-free systems to translate exogenous mRNAs. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 563:400-12. [PMID: 465497 DOI: 10.1016/0005-2787(79)90059-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The properties of the protein synthesising systems of different lymphocyte preparations have been compared with those of non-lymphoid tissues. Polysome profiles from rat thymocytes, sheep mesenteric lymphocytes, rat liver and mouse ascites tumours showed that the commitment of ribosomes to protein synthesis in lymphocytes was relatively low. Initiation factor activities, assessed on the abilities of post-mitochondrial fractions to support exogenous mRNA translation, were limited or undetectable in lymphoid tissues. While the thymocyte system translated globin mRNA, the response was enhanced by ascites extracts rich in initiation factors. The mesenteric lymphocyte system responded only marginally to globin mRNA and poly(U) but the responses were not enhanced by ascites extracts. The activity of isolated mesenteric ribosomes was comparable with ribosomes from other tissues, indicating that extraribosomal factors were responsible for the poor overall activity of the mesenteric system. Finally, the effects of cycloheximide on the recruitment of polysomes in lymphocytes indicated that the commitment of ribosomes to protein synthesis might be restricted by both limited mRNA availability and limited capacity for initiation of mRNA translation.
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Kalt MR. In vitro synthesis of RNA by Xenopus spermatogenic cells I. Evidence for polyadenylated and non-polyadenylated RNA synthesis in different cell populations. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1979; 208:77-96. [PMID: 469479 DOI: 10.1002/jez.1402080110] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Premeiotic and postmeiotic (haploid) gene expression during spermatogenesis in the anuran, Xenopus laevis, was studied by analyzing the accumulation of radioactively labelled cytoplasmic polyadenylated [poly (A +)] and non-polyadenylated [poly (A -)] RNAs. Dissociated spermatogenic cells were labelled and maintained in an in vitro system capable of supporting cell differentiation. Labelled cells were separated by density gradient centrifugation into subpopulations enriched for individual spermatogenic stages. RNA was extracted and purified from each cell fraction, and separated into poly (A +) and poly (A -) species. Comparison of poly (A +) to non-poly (A) radioactivity in cells labelled with tritiated uridine or adenosine demonstrated that (1) all cell fractions produced significant quantities of polyadenylated RNA relative to total RNA synthesis; and (2) that a cell fraction enriched for pachytene spermatocyte RNA contained up to 15% of total cytoplasmic and 35% of total polysomal RNA labelled as poly (A +) containing species. RNA was also characterized by sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. All cell types showed typical poly (A -) peaks of 4S, 18S and 28S, corresponding to tRNA (4S) and rRNAs (18, 28S) respectively. Spermatids and spermatozoa had additional absorbance peaks at 13 and 21S which cosedimented with Xenopus oocyte mitochondrial rRNA. Patterns of incorporation of uridine and adenosine into poly (A +) RNA in all germ cell fractions tested were complex. In all cases, major areas of radioactivity were found in a broad band sedimenting between 6-17S. Spermatid fractions showed a prominent peak of incorporation at 6-8S, while pachytene cells also showed heavier poly (A +) peaks in the 17-25S region. A non-polyadenylated RNA species sedimenting at 6-8S with a relatively rapid rate of turnover was also observed in spermatids. From these results it is concluded that synthesis of transfer, ribosomal, and putative messenger RNA species continues in spermatogenic cells throughout all but the very last stages of spermatogenesis in Xenopus.
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Harms-Ringdahl M, Cooper HL. Sequential changes in ribosomal activity during the activation and cessation of growth in lymphocytes stimulated with concanavalin A. J Cell Physiol 1978; 97:253-63. [PMID: 701390 DOI: 10.1002/jcp.1040970214] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Stanners CP, Wightman TM, Harkins JL. Effect of extreme amino acid starvation on the protein synthetic machinery of CHO cells. J Cell Physiol 1978; 95:125-37. [PMID: 246869 DOI: 10.1002/jcp.1040950202] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
When CHO cells are incubated under conditions of extreme amino acid starvation, effected by withdrawal of an amino acid from the medium together with genetic or chemical interference with the activity of the corresponding aminoacyl-tRNA synthetase, there is a rapid and profound decline in the functional capacity of the protein synthetic machinery. The effect was observed for all amino acids tested including leucine, asparagine, histidine, methionine and glutamine. This decline in protein synthetic potential appears to be due to a progressive permanent inactivation of the specific aminoacyl-tRNA synthetase concerned, as shown by a decline in the amount of cellular, specific aminoacyl-tRNA and a decline in the cell-free enzyme activity, measured after reversal of the starvation conditions. When cells are left for more than several hours under these starvation conditions, they shrink in size, lose viability and eventually disintegrate, with anomalous rapidity. We suggest that the progressive loss of protein synthetic capacity of the cells is the prime cause of these subsequent events. If the starvation conditions are reversed before cell death, regeneration of the protein synthetic potential occurs rapidly but requires protein synthesis itself, implying the existence of strong control mechanisms for cellular aminoacyl-tRNA synthetase activities.
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Hauser H, Knippers R, Schäfer KP. Increased rate of RNA-polyadenylation. An early response in Concanavalin A activated lymphocytes. Exp Cell Res 1978; 111:175-84. [PMID: 563795 DOI: 10.1016/0014-4827(78)90247-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Ramagopal S, Huang B, Marcus A. Modulation of protein synthesis during the growth cycle of a culture of scarlet rose. J Cell Physiol 1977; 93:319-29. [PMID: 304062 DOI: 10.1002/jcp.1040930302] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Mendelsohn SL, Nordeen SK, Young DA. Rapid changes in initiation-limited rates of protein synthesis in rat thymic lymphocytes correlate with energy charge. Biochem Biophys Res Commun 1977; 79:53-60. [PMID: 303518 DOI: 10.1016/0006-291x(77)90059-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Cooper HL, Braverman R. Free fibosomes and growth stimulation in human peripheral lymphocytes: activation of free ribisomes as an essential event in growth induction. J Cell Physiol 1977; 93:213-25. [PMID: 591563 DOI: 10.1002/jcp.1040930207] [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: 12/23/2022]
Abstract
During the initial ten hours of growth in lymphocytes stimulated by phytohemagglutinin, the cells are converted from a state in which over 70% of all ribosomes are inactive free ribosomes, to one in which over 80% of ribosomes are in polysomes or in native ribosomal subunits. In this initial period, there was a neglible increase in total ribosomal RNA due to increased RNA synthesis, and abolition of ribosomal RNA synthesis with low concentrations of actinomycin D did not interfere with polysome formation. Therefore, the conversion is accomplished by the activation of existing free ribosomes rather than by accumulation of newly synthesized particles. The large free ribosome pool of resting lymphocytes is thus an essential source of components for accelerated protein synthesis early in lymphocyte activation, before increased synthesis can provide a sufficient number of new ribosomes. Free ribosomes accumulate once more after 24 to 48 hours of growth, when RNA and DNA synthetic activity are maximal. This reaccumulation of inactive ribosomes at the peak of growth activity may represent preparation for a return to the resting state where cells are again susceptible to stimulation. Activation of free ribosomes to form polysomes appears to involve modification of at least two steps: (a) dissociation of free ribosomes with stabilization as native subunits, and (b) adjustment of a rate-limiting step at initiation.
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