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Vinogradov SN, Hoogewijs D, Bailly X, Arredondo-Peter R, Gough J, Dewilde S, Moens L, Vanfleteren JR. A phylogenomic profile of globins. BMC Evol Biol 2006; 6:31. [PMID: 16600051 PMCID: PMC1457004 DOI: 10.1186/1471-2148-6-31] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 04/07/2006] [Indexed: 12/26/2022] Open
Abstract
Background Globins occur in all three kingdoms of life: they can be classified into single-domain globins and chimeric globins. The latter comprise the flavohemoglobins with a C-terminal FAD-binding domain and the gene-regulating globin coupled sensors, with variable C-terminal domains. The single-domain globins encompass sequences related to chimeric globins and «truncated» hemoglobins with a 2-over-2 instead of the canonical 3-over-3 α-helical fold. Results A census of globins in 26 archaeal, 245 bacterial and 49 eukaryote genomes was carried out. Only ~25% of archaea have globins, including globin coupled sensors, related single domain globins and 2-over-2 globins. From one to seven globins per genome were found in ~65% of the bacterial genomes: the presence and number of globins are positively correlated with genome size. Globins appear to be mostly absent in Bacteroidetes/Chlorobi, Chlamydia, Lactobacillales, Mollicutes, Rickettsiales, Pastorellales and Spirochaetes. Single domain globins occur in metazoans and flavohemoglobins are found in fungi, diplomonads and mycetozoans. Although red algae have single domain globins, including 2-over-2 globins, the green algae and ciliates have only 2-over-2 globins. Plants have symbiotic and nonsymbiotic single domain hemoglobins and 2-over-2 hemoglobins. Over 90% of eukaryotes have globins: the nematode Caenorhabditis has the most putative globins, ~33. No globins occur in the parasitic, unicellular eukaryotes such as Encephalitozoon, Entamoeba, Plasmodium and Trypanosoma. Conclusion Although Bacteria have all three types of globins, Archaeado not have flavohemoglobins and Eukaryotes lack globin coupled sensors. Since the hemoglobins in organisms other than animals are enzymes or sensors, it is likely that the evolution of an oxygen transport function accompanied the emergence of multicellular animals.
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Affiliation(s)
- Serge N Vinogradov
- Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - David Hoogewijs
- Department of Biology, Ghent University, B-9000 Ghent, Belgium
| | - Xavier Bailly
- Station Biologique de Roscoff, 29680 Roscoff, France
| | - Raúl Arredondo-Peter
- Laboratorio de Biofísica y Biología Molecular, Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, 62210 Cuernavaca, Morelos, México
| | - Julian Gough
- RIKEN Genomic Sciences Centre, Yokohama 230-0045, Japan
| | - Sylvia Dewilde
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium
| | - Luc Moens
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium
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52
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Patterson AD, Hollander MC, Miller GF, Fornace AJ. Gadd34 requirement for normal hemoglobin synthesis. Mol Cell Biol 2006; 26:1644-53. [PMID: 16478986 PMCID: PMC1430266 DOI: 10.1128/mcb.26.5.1644-1653.2006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protein encoded by growth arrest and DNA damage-inducible transcript 34 (Gadd34) is associated with translation initiation regulation following certain stress responses. Through interaction with the protein phosphatase 1 catalytic subunit (PP1c), Gadd34 recruits PP1c for the removal of an inhibitory phosphate group on the alpha subunit of elongation initiation factor 2, thereby reversing the shutoff of protein synthesis initiated by stress-inducible kinases. In the absence of stress, the physiologic consequences of Gadd34 function are not known. Initial analysis of Gadd34-null mice revealed several significant findings, including hypersplenism, decreased erythrocyte volume, increased numbers of circulating erythrocytes, and decreased hemoglobin content, resembling some thalassemia syndromes. Biochemical analysis of the hemoglobin-producing reticulocyte (an erythrocyte precursor) revealed that the decreased hemoglobin content in the Gadd34-null erythrocyte is due to the reduced initiation of the globin translation machinery. We propose that an equilibrium state exists between Gadd34/PP1c and the opposing heme-regulated inhibitor kinase during hemoglobin synthesis in the reticulocyte.
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Affiliation(s)
- Andrew D Patterson
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
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53
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Igarashi K, Sun J. The heme-Bach1 pathway in the regulation of oxidative stress response and erythroid differentiation. Antioxid Redox Signal 2006; 8:107-18. [PMID: 16487043 DOI: 10.1089/ars.2006.8.107] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Heme--as a prosthetic group of proteins required for oxygen transport and storage, respiration, and biosynthetic pathways--is essential for practically all forms of life. Additionally, the degradation products of heme (i.e., carbon monoxide, biliverdin, and bilirubin) produced by the enzymatic actions of heme oxygenase (HO) and biliverdin reductase, possess various biological activities in vivo. In mammalian cells, heme also functions as an intracellular regulator of gene expression by virtue of its ability to bind to Bach1, a transcription factor that functions in association with small Maf proteins. Normally, such complexes function as repressors by binding to specific target sequences, the Maf recognition element (MARE), within enhancers of genes encoding proteins such as HO-1 and beta-globin. By binding to Bach1, heme induces selective removal of the repressor from the gene enhancers permitting subsequent occupancy of the MAREs by activators that, interestingly, also contain small Maf proteins. Thus small Maf proteins play dual functions in gene expression: complexes with Bach1 repress MARE-dependent gene expression, whereas heterodimers with NF-E2 p45 or related factors (Nrf1, Nrf2, and Nrf3) activate MARE-driven genes. By modulating the equilibrium of the small Maf heterodimer network, heme regulates expression of the cytoprotective enzyme HO-1 during the stress response and of beta-globin during erythroid differentiation. Implications of such heme-regulated gene expression in human diseases including atherosclerosis are discussed.
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Affiliation(s)
- Kazuhiko Igarashi
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Japan.
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54
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Abstract
Cytochrome P450 was the first hemoprotein found to have a thiolate anion as the axial ligand of the heme. Several other heme-thiolate proteins, including nitric oxide synthase, were later found in animals, plants, and microorganisms. Both cytochrome P450 and nitric oxide synthase, two major members of the heme-thiolate protein family, catalyze monooxygenase reactions, but the physiological functions of other heme-thiolate proteins are apparently highly diverse. Chloroperoxidase of a mold, Caldaryomyces fumago, catalyzes a haloperoxidase reaction. CooA of a bacterium, Rhodospirillum rubrum, and heme-regulated eIF2alpha kinase of animals function as the sensors for carbon monoxide and nitric oxide, respectively, to elicit biological responses to these gases. The role of heme in the enzymatic activity of cystathionine beta-synthase is still unknown. It is likely that more heme-thiolate proteins with diversified functions will be found in various organisms in the future.
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55
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Sarkar A, Kulkarni A, Chattopadhyay S, Mogare D, Sharma KK, Singh K, Pal JK. Lead-induced upregulation of the heme-regulated eukaryotic initiation factor 2α kinase is compromised by hemin in human K562 cells. ACTA ACUST UNITED AC 2005; 1732:15-22. [PMID: 16500424 DOI: 10.1016/j.bbaexp.2005.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 12/10/2005] [Accepted: 12/19/2005] [Indexed: 11/24/2022]
Abstract
Expression and kinase activity of the heme-regulated-eIF-2alpha kinase or -inhibitor (HRI) are induced during cytoplasmic stresses leading to inhibition of protein synthesis. Using a reporter construct with HRI promoter, we have determined the promoter activity during heat-shock and lead toxicity in human K562 cells. These two conditions induced HRI promoter activity by 2- to 3-fold. Contrary to this, hemin, a suppressor of HRI kinase activity, downregulated HRI promoter activity and stimulated hemoglobin synthesis. Interestingly, when hemin-treated cells were transfected and exposed to lead, hemin compromised lead-effect substantially by downregulating HRI promoter activity, HRI transcription and HRI kinase activity. These results together suggest that heme signaling in relation to translation regulation is not only restricted to the cytoplasm (modulating HRI kinase activity) alone but it also spans to the nucleus modulating HRI expression. Hemin may thus be useful for alleviation of stress-induced inhibition of protein synthesis.
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Affiliation(s)
- Angshuman Sarkar
- Department of Biotechnology, University of Pune, Pune 411 007, India
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56
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Yun BG, Matts JAB, Matts RL. Interdomain interactions regulate the activation of the heme-regulated eIF2α kinase. Biochim Biophys Acta Gen Subj 2005; 1725:174-81. [PMID: 16109458 DOI: 10.1016/j.bbagen.2005.07.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Revised: 07/25/2005] [Accepted: 07/25/2005] [Indexed: 10/25/2022]
Abstract
The heme-regulated inhibitor of protein synthesis (HRI) regulates translation through the phosphorylation of the alpha-subunit of eukaryotic initiation factor-2 (eIF 2). While HRI is best known for its activation in response to heme-deficiency, we recently showed that the binding of NO and CO to the N-terminal heme-binding domain (NT-HBD) of HRI activated and suppressed its activity, respectively. Here, we examined the effect of hemin, NO, and CO on the interaction between the NT-HBD and the catalytic domain of HRI (HRI/Delta HBD). Hemin stabilized the interaction of NT-HBD with HRI/Delta HBD, and NO and CO disrupted and stabilized this interaction, respectively. Mutant HRI (Delta H-HRI), lacking amino acids 116-158 from the NT-HBD, was less sensitive to heme-induced inhibition, and mutant NT-HBD lacking these residues did not bind to HRI/Delta HBD. HRI/Delta HBD and Delta H-HRI also activated more readily than HRI in response to heme-deficiency. Thus, HRI's activity is regulated through the modulation of the interaction between its NT-HBD and catalytic domain.
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Affiliation(s)
- Bo-Geon Yun
- Department of Biochemistry and Molecular Biology, Oklahoma State University, 246 NRC, Stillwater, OK 74078-3035, USA
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57
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Han AP, Fleming MD, Chen JJ. Heme-regulated eIF2alpha kinase modifies the phenotypic severity of murine models of erythropoietic protoporphyria and beta-thalassemia. J Clin Invest 2005; 115:1562-70. [PMID: 15931390 PMCID: PMC1136998 DOI: 10.1172/jci24141] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2004] [Accepted: 03/16/2005] [Indexed: 12/31/2022] Open
Abstract
Heme-regulated eIF2alpha kinase (HRI) controls protein synthesis by phosphorylating the alpha-subunit of eukaryotic translational initiation factor 2 (eIF2alpha). In heme deficiency, HRI is essential for translational regulation of alpha- and beta-globins and for the survival of erythroid progenitors. HRI is also activated by a number of cytoplasmic stresses other than heme deficiency, including oxidative stress and heat shock. However, to date, HRI has not been implicated in the pathogenesis of any known human disease or mouse phenotype. Here we report the essential role of HRI in 2 mouse models of human rbc disorders, namely erythropoietic protoporphyria (EPP) and beta-thalassemia. In both cases, lack of HRI adversely modifies the phenotype: HRI deficiency exacerbates EPP and renders beta-thalassemia embryonically lethal. This study establishes the protective function of HRI in inherited rbc diseases in mice and suggests that HRI may be a significant modifier of many rbc disorders in humans. Our findings also demonstrate that translational regulation could play a critical role in the clinical manifestation of rbc diseases.
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Affiliation(s)
- An-Ping Han
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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58
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Han XM, Lee G, Hefner C, Maher JJ, Correia MA. Heme-reversible impairment of CYP2B1/2 induction in heme-depleted rat hepatocytes in primary culture: translational control by a hepatic alpha-subunit of the eukaryotic initiation factor kinase? J Pharmacol Exp Ther 2005; 314:128-38. [PMID: 15769864 DOI: 10.1124/jpet.105.084699] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of heme in the phenobarbital-mediated induction of CYP2B1/2 was reexamined in rat hepatocytes in monolayer culture, acutely depleted of heme by treatment with either 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine (DDEP) or N-methylprotoporphyrins (NMPP). The findings revealed that such acute hepatic heme depletion markedly impaired CYP2B1/2 protein induction, an effect that was reversible by heme resupplementation. However, TaqMan analyses of hepatic mRNA isolated from these heme-depleted cells revealed that this impairment was not due to faulty transcriptional activation of either CYP2B1 or CYP2B2 gene expression as previously proposed, thereby confirming literature reports that heme is not a transcriptional regulator of the CYP2B1/2 gene. In contrast, the rate of de novo CYP2B1/2 protein synthesis was found to be dramatically inhibited in both DDEP- and NMPP-treated hepatocytes. Concurrently, a marked (>80%) suppression of de novo hepatocellular protein synthesis was also observed, along with a significantly enhanced phosphorylation of the alpha-subunit of the eukaryotic initiation factor eIF2 (eIF2alpha), as monitored by the phosphorylated eIF2alpha/total eIF2alpha ratio in these heme-depleted cells. Indeed, the parallel reversal of all these three effects by heme supplementation suggests that this impaired CYP2B1 induction most likely stems from blocked translational initiation resulting from the activation of a heme-sensitive eIF2alpha kinase. Such global suppression of hepatic protein synthesis may disrupt a myriad of vital cellular functions, thereby contributing to the clinical symptoms of acute hepatic heme-deficient states such as the hepatic porphyrias.
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Affiliation(s)
- Xing-Mei Han
- Department of Cellular and Molecular Pharmacology, Box 0450, University of California, San Francisco, CA 94143-0450, USA
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59
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Yang J, Ishimori K, O'Brian MR. Two Heme Binding Sites Are Involved in the Regulated Degradation of the Bacterial Iron Response Regulator (Irr) Protein. J Biol Chem 2005; 280:7671-6. [PMID: 15613477 DOI: 10.1074/jbc.m411664200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The iron response regulator (Irr) protein from Bradyrhizobium japonicum is a conditionally stable protein that degrades in response to cellular iron availability. This turnover is heme-dependent, and rapid degradation involves heme binding to a heme regulatory motif (HRM) of Irr. Here, we show that Irr confers iron-dependent instability on glutathione S-transferase (GST) when fused to it. Analysis of Irr-GST derivatives with C-terminal truncations of Irr implicated a second region necessary for degradation, other than the HRM, and showed that the HRM was not sufficient to confer instability on GST. The HRM-defective mutant IrrC29A degraded in the presence of iron but much more slowly than the wild-type protein. This slow turnover was heme-dependent, as discerned by the stability of Irr in a heme-defective mutant strain. Whereas the HRM of purified recombinant Irr binds ferric (oxidized) heme, a second site that binds ferrous (reduced) heme was identified based on spectral analysis of truncation and substitution mutants. A mutant in which histidines 117-119 were changed to alanines severely diminished ferrous, but not ferric, heme binding. Introduction of these substitutions in an Irr-GST fusion stabilized the protein in vivo in the presence of iron. We conclude that normal iron-dependent Irr degradation involves two heme binding sites and that both redox states of heme are required for rapid turnover.
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Affiliation(s)
- Jianhua Yang
- Department of Biochemistry, State University of New York, Buffalo, New York 14214, USA
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60
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Quigley JG, Yang Z, Worthington MT, Phillips JD, Sabo KM, Sabath DE, Berg CL, Sassa S, Wood BL, Abkowitz JL. Identification of a human heme exporter that is essential for erythropoiesis. Cell 2004; 118:757-66. [PMID: 15369674 DOI: 10.1016/j.cell.2004.08.014] [Citation(s) in RCA: 307] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 07/22/2004] [Accepted: 07/27/2004] [Indexed: 01/11/2023]
Abstract
FLVCR, a member of the major facilitator superfamily of transporter proteins, is the cell surface receptor for feline leukemia virus, subgroup C. Retroviral interference with FLVCR display results in a loss of erythroid progenitors (colony-forming units-erythroid, CFU-E) and severe anemia in cats. In this report, we demonstrate that human FLVCR exports cytoplasmic heme and hypothesize that human FLVCR is required on developing erythroid cells to protect them from heme toxicity. Inhibition of FLVCR in K562 cells decreases heme export, impairs their erythroid maturation and leads to apoptosis. FLVCR is upregulated on CFU-E, indicating that heme export is important in primary cells at this stage. Studies of FLVCR expression in cell lines suggest this exporter also impacts heme trafficking in intestine and liver. To our knowledge, this is the first description of a mammalian heme transporter.
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Affiliation(s)
- John G Quigley
- Department of Medicine/Hematology, University of Washington, Seattle 98195, USA
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61
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Akins R, McLaughlin T, Boyce R, Gilmour L, Gratton K. Exogenous metalloporphyrins alter the organization and function of cultured neonatal rat heart cells via modulation of heme oxygenase activity. J Cell Physiol 2004; 201:26-34. [PMID: 15281086 DOI: 10.1002/jcp.20040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Heme oxygenase (HO), the enzyme responsible for heme catabolism, has been associated with the function of both skeletal and smooth muscle cells and with protection of the heart against ischemia/reperfusion injury. Exposure of skeletal muscle cultures to heme, the physiological substrate for HO, has been shown to improve differentiation and aerobic metabolism. Little is known, however, about the roles that heme and heme metabolism play in cardiac muscle, and the present study was conducted to examine the effects of exogenous heme on cultured heart cells in the presence or absence of modulators of HO activity. Treatment of neonatal rat ventricular cells with heme resulted in increases in four key indicators: (1) the activity of metabolic enzymes, (2) the rate of spontaneous contraction, (3) the level of myosin heavy chain (MyHC) expressed, and (4) the amount of actin organized as filaments. Treatment with heme while metabolically inhibiting increased HO activity altered these effects such that: (1) increases in enzyme activities were attenuated, (2) spontaneous beating ceased, (3) the level of MyHC was reduced, and (4) the amount of filamentous actin was severely decreased to the point where myofibrils were no longer evident. These results suggest that heme and its catabolites act to modulate aspects of cardiac cell function and organization.
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Affiliation(s)
- Robert Akins
- Department of Biomedical Research, A. I. duPont Hospital for Children, Wilmington, Delaware, USA.
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62
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Schweizer U, Bräuer AU, Köhrle J, Nitsch R, Savaskan NE. Selenium and brain function: a poorly recognized liaison. ACTA ACUST UNITED AC 2004; 45:164-78. [PMID: 15210302 DOI: 10.1016/j.brainresrev.2004.03.004] [Citation(s) in RCA: 244] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2004] [Indexed: 01/08/2023]
Abstract
Molecular biology has recently contributed significantly to the recognition of selenium (Se)2 and Se-dependent enzymes as modulators of brain function. Increased oxidative stress has been proposed as a pathomechanism in neurodegenerative diseases including, among others, Parkinson's disease, stroke, and epilepsy. Glutathione peroxidases (GPx), thioredoxin reductases, and one methionine-sulfoxide-reductase are selenium-dependent enzymes involved in antioxidant defense and intracellular redox regulation and modulation. Selenium depletion in animals is associated with decreased activities of Se-dependent enzymes and leads to enhanced cell loss in models of neurodegenerative disease. Genetic inactivation of cellular GPx increases the sensitivity towards neurotoxins and brain ischemia. Conversely, increased GPx activity as a result of increased Se supply or overexpression ameliorates the outcome in the same models of disease. Genetic inactivation of selenoprotein P leads to a marked reduction of brain Se content, which has not been achieved by dietary Se depletion, and to a movement disorder and spontaneous seizures. Here we review the role of Se for the brain under physiological as well as pathophysiological conditions and highlight recent findings which open new vistas on an old essential trace element.
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Affiliation(s)
- Ulrich Schweizer
- Neurobiology of Selenium, Neuroscience Research Center, Charité, University Medical School, Berlin, Germany
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63
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Lan C, Lee HC, Tang S, Zhang L. A novel mode of chaperone action: heme activation of Hap1 by enhanced association of Hsp90 with the repressed Hsp70-Hap1 complex. J Biol Chem 2004; 279:27607-12. [PMID: 15102838 DOI: 10.1074/jbc.m402777200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular chaperones Hsp90 and Hsp70 control many signal transducers, including cyclin-dependent kinases and steroid receptors. The yeast heme-responsive transcriptional activator Hap1 is a native substrate of both Hsp90 and Hsp70. Hsp90 and Hsp70 are critical for the precise regulation of Hap1 activity by heme. Here, to decipher the molecular events underlying the actions of Hsp90 and Hsp70 in heme regulation, we purified various multichaperone-Hap1 complexes and characterized the complexes linked to Hap1 repression and activation by two-dimensional electrophoresis analysis. Notably, we found that in vitro Hap1 is associated continuously with Ssa and its co-chaperones, and this association is not weakened by heme. Heme enhances the interaction between Hap1 and Hsp90. In vivo, defective Ssa, Ydj1, or Sro9 function causes Hap1 derepression in the absence of heme, whereas defective Hsp90 function causes reduced Hap1 activity at high heme concentrations. These results show that continuous association of Hap1 with Ssa, Ydj1, and Sro9 confers Hap1 repression, whereas enhanced association of Hsp90 with the repressed Hap1-Ssa-Ydj1-Sro9 complex by heme causes Hap1 activation. This novel mechanism of chaperone action may operate to control the activity of other important signal transducers.
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Affiliation(s)
- Changgui Lan
- Department of Environmental Health Sciences, Columbia University, Mailman School of Public Health, New York, New York 10032, USA
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64
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Igarashi J, Sato A, Kitagawa T, Yoshimura T, Yamauchi S, Sagami I, Shimizu T. Activation of heme-regulated eukaryotic initiation factor 2alpha kinase by nitric oxide is induced by the formation of a five-coordinate NO-heme complex: optical absorption, electron spin resonance, and resonance raman spectral studies. J Biol Chem 2004; 279:15752-62. [PMID: 14752110 DOI: 10.1074/jbc.m310273200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Heme-regulated eukaryotic initiation factor 2alpha kinase (HRI) regulates the synthesis of hemoglobin in reticulocytes in response to heme availability. HRI contains a tightly bound heme at the N-terminal domain. Earlier reports show that nitric oxide (NO) regulates HRI catalysis. However, the mechanism of this process remains unclear. In the present study, we utilize in vitro kinase assays, optical absorption, electron spin resonance (ESR), and resonance Raman spectra of purified full-length HRI for the first time to elucidate the regulation mechanism of NO. HRI was activated via heme upon NO binding, and the Fe(II)-HRI(NO) complex displayed 5-fold greater eukaryotic initiation factor 2alpha kinase activity than the Fe(III)-HRI complex. The Fe(III)-HRI complex exhibited a Soret peak at 418 nm and a rhombic ESR signal with g values of 2.49, 2.28, and 1.87, suggesting coordination with Cys as an axial ligand. Interestingly, optical absorption, ESR, and resonance Raman spectra of the Fe(II)-NO complex were characteristic of five-coordinate NO-heme. Spectral findings on the coordination structure of full-length HRI were distinct from those obtained for the isolated N-terminal heme-binding domain. Specifically, six-coordinate NO-Fe(II)-His was observed but not Cys-Fe(III) coordination. It is suggested that significant conformational change(s) in the protein induced by NO binding to the heme lead to HRI activation. We discuss the role of NO and heme in catalysis by HRI, focusing on heme-based sensor proteins.
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Affiliation(s)
- Jotaro Igarashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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65
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Inuzuka T, Yun BG, Ishikawa H, Takahashi S, Hori H, Matts RL, Ishimori K, Morishima I. Identification of crucial histidines for heme binding in the N-terminal domain of the heme-regulated eIF2alpha kinase. J Biol Chem 2003; 279:6778-82. [PMID: 14672943 DOI: 10.1074/jbc.c300464200] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heme-regulated eukaryotic initiation factor-2alpha (eIF2alpha) kinase (HRI) regulates the initiation of protein synthesis in reticulocytes. The binding of NO to the N-terminal heme-binding domain (NTD) of HRI positively modulates its kinase activity. By utilizing UV-visible absorption, resonance Raman, EPR and CD spectroscopies, two histidine residues have been identified that are crucial for the binding of heme to the NTD. The UV-visible absorption and resonance Raman spectra of all the histidine to alanine mutants constructed were similar to those of the unmutated NTD. However, the change in the CD spectra of the NTD construct containing mutation of His78 to Ala (H78A) indicated loss of the specific binding of heme. The EPR spectrum for the ferric H78A mutant was also substantially perturbed. Thus, His78 is one of the axial ligands for the NTD of HRI. Significant changes in the EPR spectrum of the H123A mutant were also observed, and heme readily dissociated from both the H123A and the H78A NTD mutants, suggesting that His123 was also an axial heme ligand. However, the CD spectrum for the Soret region of the H123A mutant indicated that this mutant still bound heme specifically. Thus, while both His78 and His123 are crucial for stable heme binding, the effects of their mutations on the structure of the NTD differed. His78 appears to play the primary role in the specific binding of heme to the NTD, acting analogously to the "proximal histidine" ligand of globins, while His123 appears to act as the "distal" heme ligand.
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Affiliation(s)
- Takayuki Inuzuka
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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66
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Igarashi J, Sato A, Kitagawa T, Sagami I, Shimizu T. CO binding study of mouse heme-regulated eIF-2alpha kinase: kinetics and resonance Raman spectra. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1650:99-104. [PMID: 12922173 DOI: 10.1016/s1570-9639(03)00205-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Heme-regulated eukaryotic initiation factor (eIF)-2alpha kinase (HRI) regulates the synthesis of globin chains in reticulocytes with heme availability. In the present study, CO binding kinetics to the 6-coordinated Fe(II) heme of the amino-terminal domain of mouse HRI and resonance Raman spectra of the Fe(II)-CO complex are examined to probe the character of the heme environment. The CO association rate constant, k(on)', and CO dissociation rate constant, k(off), were 0.0029 microM(-1)s(-1) and 0.003 s(-1), respectively. These values are very slow compared with those of mouse neuroglobin and sperm whale myoglobin, while the k(off) value of HRI was close to those of the 6-coordinated hemoglobins from Chlamydomonas and barley (0.0022 and 0.0011 s(-1)). The dissociation rate constant of an endogenous ligand, which occurs prior to CO association, was 18.3 s(-1), which was lower than those (197 and 47 s(-1)) of the same 6-coordinated hemoglobins. Resonance Raman spectra suggest that the Fe-C-O adopts an almost linear and upright structure and that the bound CO interacts only weakly with nearby amino acid residues.
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Affiliation(s)
- Jotaro Igarashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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67
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Lee HC, Hon T, Lan C, Zhang L. Structural environment dictates the biological significance of heme-responsive motifs and the role of Hsp90 in the activation of the heme activator protein Hap1. Mol Cell Biol 2003; 23:5857-66. [PMID: 12897155 PMCID: PMC166322 DOI: 10.1128/mcb.23.16.5857-5866.2003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Heme-responsive motifs (HRMs) mediate heme regulation of diverse regulatory proteins. The heme activator protein Hap1 contains seven HRMs, but only one of them, HRM7, is essential for heme activation of Hap1. To better understand the molecular basis underlying the biological significance of HRMs, we examined the effects of various mutations of HRM7 on Hap1. We found that diverse mutations of HRM7 significantly diminished the extent of Hap1 activation by heme and moderately enhanced the interaction of Hap1 with Hsp90. Furthermore, deletions of nonregulatory sequences completely abolished heme activation of Hap1 and greatly enhanced the interaction of Hap1 with Hsp90. These results show that the biological functions of HRMs and Hsp90 are highly sensitive to structural changes. The unique role of HRM7 in heme activation stems from its specific structural environment, not its mere presence. Likewise, the role of Hsp90 in Hap1 activation is dictated by the conformational or structural state of Hap1, not by the mere strength of Hap1-Hsp90 interaction. It appears likely that HRM7 and Hsp90 act together to promote the Hap1 conformational changes that are necessary for Hap1 activation. Such fundamental mechanisms of HRM-Hsp90 cooperation may operate in diverse regulatory systems to mediate signal transduction.
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Affiliation(s)
- Hee Chul Lee
- Department of Biochemistry, NYU School of Medicine, New York, New York 10016, USA
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68
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Rafie-Kolpin M, Han AP, Chen JJ. Autophosphorylation of threonine 485 in the activation loop is essential for attaining eIF2alpha kinase activity of HRI. Biochemistry 2003; 42:6536-44. [PMID: 12767237 DOI: 10.1021/bi034005v] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In heme deficiency, protein synthesis is inhibited by the activation of the heme-regulated eIF2alpha kinase (HRI) through its multiple autophosphorylation. Autophosphorylation sites in HRI were identified in order to investigate their functions. We found that there were eight major tryptic phosphopeptides of HRI activated in heme deficiency. In this report we focused on the role of autophosphorylation at Thr483 and Thr485 in the activation loop of HRI. Disruption of the autophosphorylation of Thr485, but not Thr483, resulted in a lower autokinase activity and locked Thr485Ala HRI in a hypophosphorylated state. Most importantly, autophosphorylation of Thr485, but not Thr483, was essential for attaining eIF2alpha kinase activity of HRI. In addition, autophosphorylation of Thr485 was necessary for arsenite-induced activation of the eIF2alpha kinase activity of HRI, while autophosphorylation at Thr483 was not required for activation by arsenite. The function of Thr490, another conserved Thr residue in the activation loop of HRI, was also investigated. Mutations of Thr490 to either Ala or Asp resulted in reduced autokinase activity and loss of eIF2alpha kinase activity in heme deficiency or upon arsenite treatment. Since Thr490 was not identified as an autophosphorylated site, it is likely that Thr490 itself might be critical for the catalytic activity of HRI. Importantly, Thr485 was very poorly phosphorylated in Thr490 mutant HRI. Collectively, our results demonstrate that autophosphorylation of Thr485 is essential for the hyperphosphorylation and activation of HRI and is required for the acquisition of the eIF2alpha kinase activity.
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Affiliation(s)
- Maryam Rafie-Kolpin
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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69
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Garner JN, Joshi B, Jagus R. Characterization of rainbow trout and zebrafish eukaryotic initiation factor 2alpha and its response to endoplasmic reticulum stress and IPNV infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2003; 27:217-231. [PMID: 12590973 DOI: 10.1016/s0145-305x(02)00096-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The cDNAs of rainbow trout and zebrafish eIF2alpha have been isolated and found to encode proteins of similar molecular weight and isoelectric point to the alpha-subunit of the human translational initiation factor, eIF2. The rainbow trout (36.0kDa) and zebrafish (36.2kDa) eIF2alphas share 93 and 91% identity to the human protein, respectively, and are recognized by antibodies raised to the human form. In mammals, the phosphorylation of the alpha-subunit of eIF2 plays a key role in the regulation of protein synthesis in response to a range of cellular stresses. Regions corresponding to the human phosphorylation and kinase-docking sites are identical in the proteins of both fish species, as are residues that interact with the eIF2 recycling factor, eIF2B. Moreover, both recombinant rainbow trout and zebrafish eIF2alphas can be phosphorylated in vitro by the mammalian heme-sensitive eIF2alpha-kinase, HRI/HCR, as well as the interferon-inducible, dsRNA sensitive kinase, PKR. Phosphorylation of rainbow trout and zebrafish eIF2alpha can also occur in vivo. RTG-2 and ZFL cells subjected to endoplasmic reticulum (ER) stress by treatment with the Ca(2+)-ionophore A23187 showed increased levels of eIF2alpha phosphorylation, suggesting similarity between the ER stress response in fish and other higher eukaryotes. Furthermore, RTG-2 cells responded to treatment with poly(I).poly(C) or to infection by infectious pancreatic necrosis virus, IPNV, by increasing eIF2alpha phosphorylation. These data imply that RTG-2 cells express the interferon-induced eIF2alpha-kinase, PKR and suggests that the interferon/eIF2alpha/PKR response to virus infection may be a conserved vertebrate characteristic. Overall these data are consistent with the premise that fish are able to regulate protein synthesis in response to cellular stresses through phosphorylation of eIF2alpha.
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Affiliation(s)
- Joseph N Garner
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA
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70
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Zhan K, Vattem KM, Bauer BN, Dever TE, Chen JJ, Wek RC. Phosphorylation of eukaryotic initiation factor 2 by heme-regulated inhibitor kinase-related protein kinases in Schizosaccharomyces pombe is important for fesistance to environmental stresses. Mol Cell Biol 2002; 22:7134-46. [PMID: 12242291 PMCID: PMC139816 DOI: 10.1128/mcb.22.20.7134-7146.2002] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein synthesis is regulated by the phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2alpha) in response to different environmental stresses. One member of the eIF2alpha kinase family, heme-regulated inhibitor kinase (HRI), is activated under heme-deficient conditions and blocks protein synthesis, principally globin, in mammalian erythroid cells. We identified two HRI-related kinases from Schizosaccharomyces pombe which have full-length homology with mammalian HRI. The two HRI-related kinases, named Hri1p and Hri2p, exhibit autokinase and kinase activity specific for Ser-51 of eIF2alpha, and both activities were inhibited in vitro by hemin, as previously described for mammalian HRI. Overexpression of Hri1p, Hri2p, or the human eIF2alpha kinase, double-stranded-RNA-dependent protein kinase (PKR), impeded growth of S. pombe due to elevated phosphorylation of eIF2alpha. Cells from strains with deletions of the hri1(+) and hri2(+) genes, individually or in combination, exhibited a reduced growth rate when exposed to heat shock or to arsenic compounds. Measurements of in vivo phosphorylation of eIF2alpha suggest that Hri1p and Hri2p differentially phosphorylate eIF2alpha in response to these stress conditions. These results demonstrate that HRI-related enzymes are not unique to vertebrates and suggest that these eIF2alpha kinases are important participants in diverse stress response pathways in some lower eukaryotes.
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Affiliation(s)
- Ke Zhan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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71
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Han AP, Yu C, Lu L, Fujiwara Y, Browne C, Chin G, Fleming M, Leboulch P, Orkin SH, Chen JJ. Heme-regulated eIF2alpha kinase (HRI) is required for translational regulation and survival of erythroid precursors in iron deficiency. EMBO J 2001; 20:6909-18. [PMID: 11726526 PMCID: PMC125753 DOI: 10.1093/emboj/20.23.6909] [Citation(s) in RCA: 276] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Although the physiological role of tissue-specific translational control of gene expression in mammals has long been suspected on the basis of biochemical studies, direct evidence has been lacking. Here, we report on the targeted disruption of the gene encoding the heme-regulated eIF2alpha kinase (HRI) in mice. We establish that HRI, which is expressed predominantly in erythroid cells, regulates the synthesis of both alpha- and beta-globins in red blood cell (RBC) precursors by inhibiting the general translation initiation factor eIF2. This inhibition occurs when the intracellular concentration of heme declines, thereby preventing the synthesis of globin peptides in excess of heme. In iron-deficient HRI(-/-) mice, globins devoid of heme aggregated within the RBC and its precursors, resulting in a hyperchromic, normocytic anemia with decreased RBC counts, compensatory erythroid hyperplasia and accelerated apoptosis in bone marrow and spleen. Thus, HRI is a physiological regulator of gene expression and cell survival in the erythroid lineage.
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MESH Headings
- Animals
- Apoptosis
- Blotting, Northern
- Blotting, Western
- Cell Lineage
- Cell Separation
- Cell Survival
- Cloning, Molecular
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- Erythrocytes/cytology
- Erythrocytes/enzymology
- Eukaryotic Initiation Factor-2/metabolism
- Flow Cytometry
- Gene Expression Regulation, Enzymologic
- Gene Library
- Genotype
- Heme/biosynthesis
- Iron/metabolism
- Iron Deficiencies
- Mice
- Microscopy, Electron
- Models, Biological
- Phosphorylation
- Polyribosomes/metabolism
- Protein Binding
- Protein Biosynthesis
- Protein Structure, Tertiary
- Protoporphyrins/biosynthesis
- Reticulocytes/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Stress, Physiological
- Time Factors
- eIF-2 Kinase/metabolism
- eIF-2 Kinase/physiology
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Affiliation(s)
- An-Ping Han
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Channing Yu
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Linrong Lu
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Yuko Fujiwara
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Carol Browne
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Gregory Chin
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Mark Fleming
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Philippe Leboulch
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Stuart H. Orkin
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
| | - Jane-Jane Chen
- Harvard–MIT Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, Division of Hematology and Oncology, Children’s Hospital and Dana Farber Cancer Institute, Harvard Medical School, Department of Pathology, Children’s Hospital, Harvard Medical School, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 and Howard Hughes Medical Institute, Boston, MA 02115, USA Corresponding author e-mail:
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72
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Lu L, Han AP, Chen JJ. Translation initiation control by heme-regulated eukaryotic initiation factor 2alpha kinase in erythroid cells under cytoplasmic stresses. Mol Cell Biol 2001; 21:7971-80. [PMID: 11689689 PMCID: PMC99965 DOI: 10.1128/mcb.21.23.7971-7980.2001] [Citation(s) in RCA: 243] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytoplasmic stresses, including heat shock, osmotic stress, and oxidative stress, cause rapid inhibition of protein synthesis in cells through phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha) by eIF2alpha kinases. We have investigated the role of heme-regulated inhibitor (HRI), a heme-regulated eIF2alpha kinase, in stress responses of erythroid cells. We have demonstrated that HRI in reticulocytes and fetal liver nucleated erythroid progenitors is activated by oxidative stress induced by arsenite, heat shock, and osmotic stress but not by endoplasmic reticulum stress or nutrient starvation. While autophosphorylation is essential for the activation of HRI, the phosphorylation status of HRI activated by different stresses is different. The contributions of HRI in various stress responses were assessed with the aid of HRI-null reticulocytes and fetal liver erythroid cells. HRI is the only eIF2alpha kinase activated by arsenite in erythroid cells, since HRI-null cells do not induce eIF2alpha phosphorylation upon arsenite treatment. HRI is also the major eIF2alpha kinase responsible for the increased eIF2alpha phosphorylation upon heat shock in erythroid cells. Activation of HRI by these stresses is independent of heme and requires the presence of intact cells. Both hsp90 and hsc70 are necessary for all stress-induced HRI activation. However, reactive oxygen species are involved only in HRI activation by arsenite. Our results provide evidence for a novel function of HRI in stress responses other than heme deficiency.
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Affiliation(s)
- L Lu
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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73
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Bauer BN, Rafie-Kolpin M, Lu L, Han A, Chen JJ. Multiple autophosphorylation is essential for the formation of the active and stable homodimer of heme-regulated eIF2alpha kinase. Biochemistry 2001; 40:11543-51. [PMID: 11560503 DOI: 10.1021/bi010983s] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In heme-deficient reticulocytes, protein synthesis is inhibited due to the activation of heme-regulated eIF2alpha kinase (HRI). Activation of HRI is accompanied by its phosphorylation. We have investigated the role of autophosphorylation in the formation of active and stable HRI. Two autophosphorylated species of recombinant HRI expressed in Escherichia coli were resolved by SDS-PAGE. Both species of HRI were multiply autophosphorylated on serine, threonine, and to a lesser degree also tyrosine residues. Species II HRI exhibited a much higher extent of autophosphorylation and thus migrates slower in SDS-PAGE than species I HRI. Similarly, HRI naturally present in reticulocytes also exhibited these species with different degrees of phosphorylation. Importantly, in heme-deficient intact reticulocytes, inactive species I HRI was converted completely into species II. We further separated and characterized these two species biochemically. We found that species I was inactive and had a tendency to aggregate while the more extensively autophosphorylated species II was an active heme-regulated eIF2alpha kinase and stable homodimer. Our results strongly suggest that autophosphorylation regulates HRI in a two-stage mechanism. In the first stage, autophosphorylation of newly synthesized HRI stabilizes species I HRI against aggregation. Although species I is an active autokinase, it is still without eIF2alpha kinase activity. Additional multiple autophosphorylation in the second stage is required for the formation of stable dimeric HRI (species II) with eIF2alpha kinase activity that is regulated by heme.
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Affiliation(s)
- B N Bauer
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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74
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Huang TJ, McCoubrey WK, Maines MD. Heme oxygenase-2 interaction with metalloporphyrins: function of heme regulatory motifs. Antioxid Redox Signal 2001; 3:685-96. [PMID: 11554454 DOI: 10.1089/15230860152543023] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Heme oxygenase-2 (HO-2) degrades heme [Fe-protoporphyrin IX (Fe-PP)] to CO and bilirubin. The enzyme is a hemoprotein and interacts with nitric oxide. HO-2 has two copies of heme regulatory motif (HRM) with a conserved core of Cys264-Pro265 and Cys281-Pro282. We examined interaction of HO-2 HRMs with Fe-PP, Zn-protoporphyrin IX (Zn-PP; HO-2 inhibitor), and protoporphyrin IX (PP IX). Spectral analyses, using 1:4 or 1:1 molar ratio of the heme to 10-residue peptides, corresponding to HRM containing HO-2 sequences, revealed specific interactions as indicated by a shift in the absorption spectrum of heme. Five residue peptides qualitatively produced similar results. Substitution of cysteine with alanine in either peptide eliminated interactions, and substitution of proline with alanine reduced the peptides' affinity for heme. Neither Zn-PP nor PP IX absorption spectrum was affected by HRM peptides. The circular dichroism spectra confirmed heme-HRM peptides interactions. An astounding 4,000-6,000-fold higher concentrations of KCN were required at pH 7.5 to displace HRM peptides from heme. Data suggest (a) each HRM can contribute to HO-2-heme interaction, (b) heme iron interacts with cysteine thiol, (c) charged residues upstream of Cys264-Pro265 result in its high-affinity heme binding, and (d) inhibition of HO-2 activity by synthetic metalloporphyrins does not involve HRMs. We suggest that heme bound to HRMs may serve as a binding site/reservoir for gaseous signal molecules.
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Affiliation(s)
- T J Huang
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, NY 14642, USA
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75
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Ogawa K, Sun J, Taketani S, Nakajima O, Nishitani C, Sassa S, Hayashi N, Yamamoto M, Shibahara S, Fujita H, Igarashi K. Heme mediates derepression of Maf recognition element through direct binding to transcription repressor Bach1. EMBO J 2001; 20:2835-43. [PMID: 11387216 PMCID: PMC125477 DOI: 10.1093/emboj/20.11.2835] [Citation(s) in RCA: 408] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Heme controls expression of genes involved in the synthesis of globins and heme. The mammalian transcription factor Bach1 functions as a repressor of the Maf recognition element (MARE) by forming antagonizing hetero-oligomers with the small Maf family proteins. We show here that heme binds specifically to Bach1 and regulates its DNA-binding activity. Deletion studies demonstrated that a heme-binding region of Bach1 is confined within its C-terminal region that possesses four dipeptide cysteine-proline (CP) motifs. Mutations in all of the CP motifs of Bach1 abolished its interaction with heme. The DNA-binding activity of Bach1 as a MafK hetero-oligomer was markedly inhibited by heme in gel mobility shift assays. The repressor activity of Bach1 was lost upon addition of hemin in transfected cells. These results suggest that increased levels of heme inactivate the repressor Bach1, resulting in induction of a host of genes with MARES:
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Affiliation(s)
- Kazuhiro Ogawa
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Jiying Sun
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Shigeru Taketani
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Osamu Nakajima
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Chiaki Nishitani
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Shigeru Sassa
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Norio Hayashi
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Masayuki Yamamoto
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Shigeki Shibahara
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Hiroyoshi Fujita
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
| | - Kazuhiko Igarashi
- Laboratory of Environmental Biology, Hokkaido University School of Medicine, Sapporo 060-8638, Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai 980-8575, Department of Biochemistry, Hiroshima University School of Medicine, Kasumi 1-2-3, Minami-Ku, Hiroshima 734-8551, Kyoto Institute of Technology, Kyoto 600-8585, Research Laboratory for Molecular Genetics, Yamagata University, Yamagata 990-9585, Department of Biochemistry, Tohoku University School of Medicine, Sendai 980-8575, Center for Tsukuba Advanced Research Alliance and Institute of Basic Medicine, University of Tsukuba, Tsukuba 305-8575, Japan and The Rockefeller University, New York, NY 10021, USA Present address: Yamanouchi Pharmaceutical Co., Ltd, Itabashi-ku, Tokyo 174-0046, Japan Corresponding author e-mail:
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Uma S, Yun BG, Matts RL. The heme-regulated eukaryotic initiation factor 2alpha kinase. A potential regulatory target for control of protein synthesis by diffusible gases. J Biol Chem 2001; 276:14875-83. [PMID: 11278914 DOI: 10.1074/jbc.m011476200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Nitric oxide (NO) has been reported to inhibit protein synthesis in eukaryotic cells by increasing the phosphorylation of the alpha-subunit of eukaryotic initiation factor (eIF) 2. However, the mechanism through which this increase occurs has not been characterized. In this report, we examined the effect of the diffusible gases nitric oxide (NO) and carbon monoxide (CO) on the activation of the heme-regulated eIF2alpha kinase (HRI) in rabbit reticulocyte lysate. Spectral analysis indicated that both NO and CO bind to the N-terminal heme-binding domain of HRI. Although NO was a very potent activator of HRI, CO markedly suppressed NO-induced HRI activation. The NO-induced activation of HRI was transduced through the interaction of NO with the N-terminal heme-binding domain of HRI and not through S-nitrosylation of HRI. We postulate that the regulation of HRI activity by diffusible gases may be of wider physiological significance, as we further demonstrate that NO generators increase eIF2alpha phosphorylation levels in NT2 neuroepithelial and C2C12 myoblast cells and activate HRI immunoadsorbed from extracts of these non-erythroid cell lines.
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Affiliation(s)
- S Uma
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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77
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Regulation of hemoglobin synthesis and proliferation of differentiating erythroid cells by heme-regulated eIF-2α kinase. Blood 2000. [DOI: 10.1182/blood.v96.9.3241] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractProtein synthesis in reticulocytes depends on the availability of heme. In heme deficiency, inhibition of protein synthesis correlates with the activation of heme-regulated eIF-2α kinase (HRI), which blocks the initiation of protein synthesis by phosphorylating eIF-2α. HRI is a hemoprotein with 2 distinct heme-binding domains. Heme negatively regulates HRI activity by binding directly to HRI. To further study the physiological function of HRI, the wild-type (Wt) HRI and dominant-negative inactive mutants of HRI were expressed by retrovirus-mediated transfer in both non-erythroid NIH 3T3 and mouse erythroleukemic (MEL) cells. Expression of Wt HRI in 3T3 cells resulted in the inhibition of protein synthesis, a loss of proliferation, and eventually cell death. Expression of the inactive HRI mutants had no apparent effect on the growth characteristics or morphology of NIH 3T3 cells. In contrast, expression of 3 dominant-negative inactive mutants of HRI in MEL cells resulted in increased hemoglobin production and increased proliferative capacity of these cells upon dimethyl-sulfoxide induction of erythroid differentiation. These results directly demonstrate the importance of HRI in the regulation of protein synthesis in immature erythroid cells and suggest a role of HRI in the regulation of the numbers of matured erythroid cells.
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78
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Regulation of hemoglobin synthesis and proliferation of differentiating erythroid cells by heme-regulated eIF-2α kinase. Blood 2000. [DOI: 10.1182/blood.v96.9.3241.h8003241_3241_3248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein synthesis in reticulocytes depends on the availability of heme. In heme deficiency, inhibition of protein synthesis correlates with the activation of heme-regulated eIF-2α kinase (HRI), which blocks the initiation of protein synthesis by phosphorylating eIF-2α. HRI is a hemoprotein with 2 distinct heme-binding domains. Heme negatively regulates HRI activity by binding directly to HRI. To further study the physiological function of HRI, the wild-type (Wt) HRI and dominant-negative inactive mutants of HRI were expressed by retrovirus-mediated transfer in both non-erythroid NIH 3T3 and mouse erythroleukemic (MEL) cells. Expression of Wt HRI in 3T3 cells resulted in the inhibition of protein synthesis, a loss of proliferation, and eventually cell death. Expression of the inactive HRI mutants had no apparent effect on the growth characteristics or morphology of NIH 3T3 cells. In contrast, expression of 3 dominant-negative inactive mutants of HRI in MEL cells resulted in increased hemoglobin production and increased proliferative capacity of these cells upon dimethyl-sulfoxide induction of erythroid differentiation. These results directly demonstrate the importance of HRI in the regulation of protein synthesis in immature erythroid cells and suggest a role of HRI in the regulation of the numbers of matured erythroid cells.
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