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Lorch SA, Foust R, Gow A, Arkovitz M, Salzman AL, Szabo C, Vayert B, Geffard M, Ischiropoulos H. Immunohistochemical localization of protein 3-nitrotyrosine and S-nitrosocysteine in a murine model of inhaled nitric oxide therapy. Pediatr Res 2000; 47:798-805. [PMID: 10832741 DOI: 10.1203/00006450-200006000-00020] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Inhaled nitric oxide (INO) therapy is currently used clinically to selectively dilate the pulmonary vasculature and to help treat persistent pulmonary hypertension and bronchopulmonary dysplasia in the neonate. However, in the presence of oxygen or superoxide, nitric oxide forms potentially harmful reactive nitrogen species. Using an experimental mice model, we examined the effects of concurrent hyperoxia and INO on protein tyrosine nitration and cysteine S-nitrosylation in pulmonary tissue. Data showed enhanced 3-nitrotyrosine staining within the airway epithelium and alveolar interstitium of mice lungs treated with hyperoxia, which did not increase significantly with INO administration. Within the alveolar interstitium, 3-nitrotyrosine staining was localized to macrophages. S-Nitrosocysteine staining in airway epithelium was significantly enhanced with INO administration regardless of oxygen content. These data suggest that the formation of protein S-nitrosocysteine is the major protein modification during administration of INO.
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Stecca B, Southwood CM, Gragerov A, Kelley KA, Friedrich VL, Gow A. The evolution of lipophilin genes from invertebrates to tetrapods: DM-20 cannot replace proteolipid protein in CNS myelin. J Neurosci 2000; 20:4002-10. [PMID: 10818135 PMCID: PMC6772626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
The proteolipid protein (PLP) gene encodes two myelin-specific protein isoforms, DM-20 and PLP, which are members of the highly conserved lipophilin family of transmembrane proteins. While the functions of this family are poorly understood, the fact that null mutations of the PLP gene cause leukodystrophy in man is testament to the importance of DM-20 and PLP in normal CNS function. PLP differs from DM-20 by the presence of a 35 amino acid domain exposed to the cytoplasm, which is not encoded by other lipophilin genes and appears to have arisen in amphibians approximately 300 million years before present. However, the lipophilin gene family can be traced back at least 550 million years and is represented in Drosophila and silkworms. Thus, from an evolutionary perspective PLP can reasonably be anticipated to perform functions in CNS myelin that cannot be accomplished by other lipophilins. Herein we use a novel knock-in strategy to generate mice expressing wild-type levels of a Plp gene that has been modified to encode only DM-20. Although DM-20 is incorporated into functional compact myelin sheaths in young animals, our data show that the 35 amino acid PLP-specific peptide is required to engender the normal myelin period and to confer long-term stability on this multilamellar membrane.
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Gow AJ, Chen Q, Gole M, Themistocleous M, Lee VM, Ischiropoulos H. Two distinct mechanisms of nitric oxide-mediated neuronal cell death show thiol dependency. Am J Physiol Cell Physiol 2000; 278:C1099-107. [PMID: 10837337 DOI: 10.1152/ajpcell.2000.278.6.c1099] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To better understand the mechanism(s) underlying nitric oxide (. NO)-mediated toxicity, in the presence and absence of concomitant oxidant exposure, postmitotic terminally differentiated NT2N cells, which are incapable of producing. NO, were exposed to PAPA-NONOate (PAPA/NO) and 3-morpholinosydnonimine (SIN-1). Exposure to SIN-1, which generated peroxynitrite in the range of 25-750 nM/min, produced a concentration- and time-dependent delayed cell death. In contrast, a critical threshold concentration (>440 nM/min) was required for. NO to produce significant cell injury. Examination of cells by electron microscopy shows a largely necrotic injury after peroxynitrite exposure but mainly apoptotic-like morphology after. NO exposure. Cellular levels of reduced thiols correlated with cell death, and pretreatment with N-acetylcysteine (NAC) fully protected from cell death in either PAPA/NO or SIN-1 exposure. NAC given within the first 3 h posttreatment further delayed cell death and increased the intracellular thiol level in SIN-1 but not. NO-exposed cells. Cell injury from. NO was independent of cGMP, caspases, and superoxide or peroxynitrite formation. Overall, exposure of non-. NO-producing cells to. NO or peroxynitrite results in delayed cell death, which, although occurring by different mechanisms, appears to be mediated by the loss of intracellular redox balance.
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Gow A, Southwood CM, Li JS, Pariali M, Riordan GP, Brodie SE, Danias J, Bronstein JM, Kachar B, Lazzarini RA. CNS myelin and sertoli cell tight junction strands are absent in Osp/claudin-11 null mice. Cell 1999; 99:649-59. [PMID: 10612400 DOI: 10.1016/s0092-8674(00)81553-6] [Citation(s) in RCA: 554] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Oligodendrocyte-specific protein (OSP)/claudin-11 is a recently identified transmembrane protein found in CNS myelin and testis with unknown function. Herein we demonstrate that Osp null mice exhibit both neurological and reproductive deficits: CNS nerve conduction is slowed, hindlimb weakness is conspicuous, and males are sterile. Freeze fracture reveals that tight junction intramembranous strands are absent in CNS myelin and between Sertoli cells of mutant mice. Our results demonstrate that OSP is the mediator of parallel-array tight junction strands and distinguishes this protein from other intrinsic membrane proteins in tight junctions. These novel results provide direct evidence of the pivotal role of the claudin family in generating the paracellular physical barrier of tight junctions necessary for spermatogenesis and normal CNS function.
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Durner J, Gow AJ, Stamler JS, Glazebrook J. Ancient origins of nitric oxide signaling in biological systems. Proc Natl Acad Sci U S A 1999; 96:14206-7. [PMID: 10588683 PMCID: PMC33950 DOI: 10.1073/pnas.96.25.14206] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Minning DM, Gow AJ, Bonaventura J, Braun R, Dewhirst M, Goldberg DE, Stamler JS. Ascaris haemoglobin is a nitric oxide-activated 'deoxygenase'. Nature 1999; 401:497-502. [PMID: 10519555 DOI: 10.1038/46822] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The parasitic nematode Ascaris lumbricoides infects one billion people worldwide. Its perienteric fluid contains an octameric haemoglobin that binds oxygen nearly 25,000 times more tightly than does human haemoglobin. Despite numerous investigations, the biological function of this molecule has remained elusive. The distal haem pocket contains a metal, oxygen and thiol, all of which are known to be reactive with nitric oxide. Here we show that Ascaris haemoglobin enzymatically consumes oxygen in a reaction driven by nitric oxide, thus keeping the perienteric fluid hypoxic. The mechanism of this reaction involves unprecedented chemistry of a haem group, a thiol and nitric oxide. We propose that Ascaris haemoglobin functions as a 'deoxygenase', using nitric oxide to detoxify oxygen. The structural and functional adaptations of Ascaris haemoglobin suggest that the molecular evolution of haemoglobin can be rationalized by its nitric oxide related functions.
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Gow AJ, Luchsinger BP, Pawloski JR, Singel DJ, Stamler JS. The oxyhemoglobin reaction of nitric oxide. Proc Natl Acad Sci U S A 1999; 96:9027-32. [PMID: 10430889 PMCID: PMC17726 DOI: 10.1073/pnas.96.16.9027] [Citation(s) in RCA: 344] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The oxidation of nitric oxide (NO) to nitrate by oxyhemoglobin is a fundamental reaction that shapes our understanding of NO biology. This reaction is considered to be the major pathway for NO elimination from the body; it is the basis for a prevalent NO assay; it is a critical feature in the modeling of NO diffusion in the circulatory system; and it informs a variety of therapeutic applications, including NO-inhalation therapy and blood substitute design. Here we show that, under physiological conditions, this reaction is of little significance. Instead, NO preferentially binds to the minor population of the hemoglobin's vacant hemes in a cooperative manner, nitrosylates hemoglobin thiols, or reacts with liberated superoxide in solution. In the red blood cell, superoxide dismutase eliminates superoxide, increasing the yield of S-nitrosohemoglobin and nitrosylated hemes. Hemoglobin thus serves to regulate the chemistry of NO and maintain it in a bioactive state. These results represent a reversal of the conventional view of hemoglobin in NO biology and motivate a reconsideration of fundamental issues in NO biochemistry and therapy.
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Gow AJ, Branco F, Christofidou-Solomidou M, Black-Schultz L, Albelda SM, Muzykantov VR. Immunotargeting of glucose oxidase: intracellular production of H(2)O(2) and endothelial oxidative stress. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:L271-81. [PMID: 10444521 DOI: 10.1152/ajplung.1999.277.2.l271] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extracellular and intracellular reactive oxygen species attack different targets and may, therefore, result in different forms of oxidative stress. To specifically study an oxidative stress induced by a regulated intracellular flux of a defined reactive oxygen species in endothelium, we used immunotargeting of the H(2)O(2)-generating enzyme glucose oxidase (GOX) conjugated with an antibody to platelet-endothelial cell adhesion molecule (PECAM)-1, an endothelial surface antigen. Anti-PECAM-(125)I-GOX conjugates specifically bind to both endothelial and PECAM-transfected cells. Approximately 70% of cell-bound anti-PECAM-(125)I-GOX was internalized. The cell-bound conjugate was enzymatically active and generated H(2)O(2) from glucose. Use of the fluorescent dye dihydrorhodamine 123 revealed that 70% of H(2)O(2) was generated intracellularly, whereas 30% of H(2)O(2) was detected in the cell medium. Catalase added to the cells eliminated H(2)O(2) in the medium but had little effect on the intracellular generation of H(2)O(2) by anti-PECAM-GOX. Both H(2)O(2) added exogenously to the cell medium (extracellular H(2)O(2)) and that generated by anti-PECAM-GOX caused oxidative stress manifested by time- and dose-dependent irreversible plasma membrane damage. Inactivation of cellular catalase by aminotriazole treatment augmented damage caused by either extracellular H(2)O(2) or anti-PECAM-GOX. Catalase added to the medium protected either normal or aminotriazole-treated cells against extracellular H(2)O(2), yet failed to protect cells against injury induced by anti-PECAM-GOX. Therefore, treatment of PECAM-positive cells with anti-PECAM-GOX leads to conjugate internalization, predominantly intracellular H(2)O(2) generation and intracellular oxidative stress. These results indicate that anti-PECAM-GOX 1) provides cell-specific intracellular delivery of an active enzyme and 2) causes intracellular oxidative stress in PECAM-positive cells.
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Mannick JB, Hausladen A, Liu L, Hess DT, Zeng M, Miao QX, Kane LS, Gow AJ, Stamler JS. Fas-induced caspase denitrosylation. Science 1999; 284:651-4. [PMID: 10213689 DOI: 10.1126/science.284.5414.651] [Citation(s) in RCA: 562] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Only a few intracellular S-nitrosylated proteins have been identified, and it is unknown if protein S-nitrosylation/denitrosylation is a component of signal transduction cascades. Caspase-3 zymogens were found to be S-nitrosylated on their catalytic-site cysteine in unstimulated human cell lines and denitrosylated upon activation of the Fas apoptotic pathway. Decreased caspase-3 S-nitrosylation was associated with an increase in intracellular caspase activity. Fas therefore activates caspase-3 not only by inducing the cleavage of the caspase zymogen to its active subunits, but also by stimulating the denitrosylation of its active-site thiol. Protein S-nitrosylation/denitrosylation can thus serve as a regulatory process in signal transduction pathways.
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Ischiropoulos H, Gow A, Thom SR, Kooy NW, Royall JA, Crow JP. Detection of reactive nitrogen species using 2,7-dichlorodihydrofluorescein and dihydrorhodamine 123. Methods Enzymol 1999; 301:367-73. [PMID: 9919585 DOI: 10.1016/s0076-6879(99)01100-3] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Hausladen A, Gow AJ, Stamler JS. Nitrosative stress: metabolic pathway involving the flavohemoglobin. Proc Natl Acad Sci U S A 1998; 95:14100-5. [PMID: 9826660 PMCID: PMC24333 DOI: 10.1073/pnas.95.24.14100] [Citation(s) in RCA: 241] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) biology has focused on the tightly regulated enzymatic mechanism that transforms L-arginine into a family of molecules, which serve both signaling and defense functions. However, very little is known of the pathways that metabolize these molecules or turn off the signals. The paradigm is well exemplified in bacteria where S-nitrosothiols (SNO)-compounds identified with antimicrobial activities of NO synthase-elicit responses that mediate bacterial resistance by unknown mechanisms. Here we show that Escherichia coli possess both constitutive and inducible elements for SNO metabolism. Constitutive enzyme(s) cleave SNO to NO whereas bacterial hemoglobin, a widely distributed flavohemoglobin of poorly understood function, is central to the inducible response. Remarkably, the protein has evolved a novel heme-detoxification mechanism for NO. Specifically, the heme serves a dioxygenase function that produces mainly nitrate. These studies thus provide new insights into SNO and NO metabolism and identify enzymes with reactions that were thought to occur only by chemical means. Our results also emphasize that the reactions of SNO and NO with hemoglobins are evolutionary conserved, but have been adapted for cell-specific function.
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Gow A, Southwood CM, Lazzarini RA. Disrupted proteolipid protein trafficking results in oligodendrocyte apoptosis in an animal model of Pelizaeus-Merzbacher disease. J Cell Biol 1998; 140:925-34. [PMID: 9472043 PMCID: PMC2141744 DOI: 10.1083/jcb.140.4.925] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pelizaeus-Merzbacher disease (PMD) is a dysmyelinating disease resulting from mutations, deletions, or duplications of the proteolipid protein (PLP) gene. Distinguishing features of PMD include pleiotropy and a range of disease severities among patients. Previously, we demonstrated that, when expressed in transfected fibroblasts, many naturally occurring mutant PLP alleles encode proteins that accumulate in the endoplasmic reticulum and are not transported to the cell surface. In the present communication, we show that oligodendrocytes in an animal model of PMD, the msd mouse, accumulate Plp gene products in the perinuclear region and are unable to transport them to the cell surface. Another important aspect of disease in msd mice is oligodendrocyte cell death, which is increased by two- to threefold. We demonstrate in msd mice that this death occurs by apoptosis and show that at the time oligodendrocytes die, they have differentiated, extended processes that frequently contact axons and are expressing myelin structural proteins. Finally, we define a hypothesis that accounts for pathogenesis in most PMD patients and animal models of this disease and, moreover, can be used to develop potential therapeutic strategies for ameliorating the disease phenotype.
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Gow AJ, Stamler JS. Reactions between nitric oxide and haemoglobin under physiological conditions. Nature 1998; 391:169-73. [PMID: 9428761 DOI: 10.1038/34402] [Citation(s) in RCA: 472] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The tenet of high-affinity nitric oxide (NO) binding to a haemoglobin (Hb) has shaped our view of haem proteins and of small diffusible signaling molecules. Specifically, NO binds rapidly to haem iron in Hb (k approximately 10[7] M[-1] s[-1]) and once bound, the NO activity is largely irretrievable (Kd approximately 10[-5] s[-1]); the binding is purportedly so tight as to be unaffected by O2 or CO. However, these general principles do not consider the allosteric state of Hb or the nature of the allosteric effector, and they mostly derive from the functional behaviour of fully nitrosylated Hb, whereas Hb is only partially nitrosylated in vivo. Here we show that oxygen drives the conversion of nitrosylhaemoglobin in the 'tense' T (or partially nitrosylated, deoxy) structure to S-nitrosohaemoglobin in the 'relaxed' R (or ligand-bound, oxy) structure. In the absence of oxygen, nitroxyl anion (NO-) is liberated in a reaction producing methaemoglobin. The yields of both S-nitrosohaemoglobin and methaemoglobin are dependent on the NO/Hb ratio. These newly discovered reactions elucidate mechanisms underlying NO function in the respiratory cycle, and provide insight into the aetiology of S-nitrosothiols, methaemoglobin and its related valency hybrids. Mechanistic reexamination of NO interactions with other haem proteins containing allosteric-site thiols may be warranted.
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Gow AJ, Thom SR, Ischiropoulos H. Nitric oxide and peroxynitrite-mediated pulmonary cell death. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:L112-8. [PMID: 9458808 DOI: 10.1152/ajplung.1998.274.1.l112] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nitric oxide (.NO) can be produced within the lung, and recently inhaled nitric oxide has been used as a therapeutic agent. Peroxynitrite1 (ONOO-), the product of the nearly diffusion-limited reaction between .NO and superoxide, may represent the proximal reactive species mediating .NO injury to pulmonary cells. To investigate the physiological and pathological reactivities of .NO and ONOO- at the molecular and cellular levels, bovine pulmonary artery endothelial cells (BPAEC) and rat type II epithelial cells were exposed to .NO (0.01-2.5 microM/min for 2 h) generated by spermine-NONOate and papa-NONOate and to the same fluxes of ONOO- generated by 1,3-morpholinosydnonimine (SIN-1). Exposure to SIN-1 resulted in cellular injury and death in both cell types. Epithelial cells displayed a concentration-dependent loss of cellular viability within 8 h of exposure. In contrast, BPAEC loss of cellular viability was evident after 18 h postexposure. Events preceding cell death in BPAEC include depolarization of the mitochondrial membrane, evident as early as 6 h postexposure, loss of cellular redox activity at 16 h, and DNA fragmentation detected by in situ staining at 18 h after exposure. Exposure of BPAEC to .NO did not affect the cellular viability, but type II cells were injured in a manner similar to ONOO- exposure. .NO-mediated cellular injury within type II cells was reduced by preincubation with N-acetylcysteine. The data imply that the pathological and physiological effects of .NO may be regulated by its reactions with superoxide and reduced thiols.
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Tosic M, Matthey B, Gow A, Lazzarini RA, Matthieu JM. Intracellular transport of the DM-20 bearing shaking pup (shp) mutation and its possible phenotypic consequences. J Neurosci Res 1997; 50:844-52. [PMID: 9418971 DOI: 10.1002/(sici)1097-4547(19971201)50:5<844::aid-jnr20>3.0.co;2-#] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Paralytic tremor (pt) in rabbits and shaking pup (shp) in dogs are allelic dysmyelinated mutants of the proteolipid protein (Plp) gene. Both mutations affect the same amino acid, histidine36, which is replaced by glutamine in pt and by proline in shp. Phenotypic expression of these two mutations is very different. Paralytic tremor presents a much milder form of dysmyelination than shaking pup. The number of oligodendrocytes in the mutant rabbit is normal, while in the dog, the oligodendrocyte number is reduced due to early death or incomplete maturation. We have previously reported an abnormal intracellular transport of the PLPpt, whereas DM-20pt was normally transported to the cell membrane. In the present study, we show that the transport of the two isoforms containing the shp mutation is impaired in transfected Cos-7 cells. Cotransfecting cells with different ratios and combinations of mutated PLP and DM-20 cDNAs, we demonstrated that DM-20pt, but not DM-20shp, facilitates intracellular trafficking and integration into the plasma membrane of either of the two mutated PLPs. The phenotypic difference between these two allelic mutations can result from differences in DM-20 protein trafficking and sorting. These results show that the loss of function of PLP is not position-dependent but depends on the nature of the mutation.
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Abstract
The past few years have seen a dramatic increase in our understanding, in molecular terms, of the involvement of the central nervous system proteolipid protein in myelinogenesis and X-linked genetic diseases. In addition, we have expanded our knowledge of the proteins that have been recruited into the vertebrate myelin membrane over the past 400 million years with the molecular cloning of several cDNAs encoding proteins which are homologous to the proteolipid protein gene. In searching for a name to distinguish these proteins from other "proteolipid" proteins of nonneural origin I propose that we resurrect the term "lipophilins" which describes a small family of unusually hydrophobic integral membrane proteins exhibiting identical topologies and similar physical properties. Two subgroups are distinguishable among the lipophilins based on the patterns of expression during development and the presence or absence of a small motif that is exposed to the extracellular space.
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Libonati JR, Gaughan JP, Hefner CA, Gow A, Paolone AM, Houser SR. Reduced ischemia and reperfusion injury following exercise training. Med Sci Sports Exerc 1997; 29:509-16. [PMID: 9107634 DOI: 10.1097/00005768-199704000-00013] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We examined the effects of two exercise training modalities, i.e., low-intensity endurance and sprint running, on in vitro, isovolumic myocardial performance following ischemia and reperfusion. Rats ran on a treadmill 5 d.wk-1 for 6 wk at the following levels: endurance; 20 m.min-1, 0% grade, 60 min.d-1 and sprint; five 1-min runs at 75 m.min-1, 15% grade interspersed with 1-min active recovery runs at 20 m.min-1, 15% grade. Both endurance and sprint training significantly improved exercise tolerance relative to control (P < 0.05) on two graded exercise tests. Buffer perfused hearts of control (N = 18), endurance (N = 20), and sprint (N = 13) trained animals underwent no-flow ischemia (20 min) and reperfusion (30 min) in a Langendorff mode. During reperfusion, left ventricular developed pressure and its first derivative were 20% higher in sprint (P < 0.05) than either endurance or control hearts. Left ventricular end-diastolic pressure was lowest in sprint during reperfusion (sprint, 10 +/- 1 mm Hg vs endurance, 14 +/- 2 mm Hg; and control, 14 +/- 2 mm Hg, at 30 min reperfusion). Hearts were then used for biochemical studies or dissociated into single cells for measurement of contraction, cell calcium, and action potential duration. Single cell contractions were greatest in sprint despite similar calcium transients in all groups. Ischemia/reperfusion caused action potential prolongation in control but not trained myocytes. Hearts from sprint had the greatest glyceraldehyde-3-phosphate dehydrogenase activity (P < 0.05) and a tendency towards increased superoxide dismutase activity. These results suggest that sprinting increases myocardial resistance to ischemia/reperfusion. This protection may be secondary to increased myofilament calcium sensitivity and/or myocardial expression of glyceraldehyde-3-phosphate dehydrogenase.
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Gow AJ, Buerk DG, Ischiropoulos H. A novel reaction mechanism for the formation of S-nitrosothiol in vivo. J Biol Chem 1997; 272:2841-5. [PMID: 9006926 DOI: 10.1074/jbc.272.5.2841] [Citation(s) in RCA: 244] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The objective of this study was to investigate the mechanism of S-nitrosothiol formation under physiological conditions. A mechanism is proposed by which nitric oxide (.NO) reacts directly with reduced thiol to produce a radical intermediate, R-S-N.-O-H. This intermediate reduces an electron acceptor to produce S-nitrosothiol. Under aerobic conditions O2 acts as the electron acceptor and is reduced to produce superoxide (O-2). The following experimental evidence is provided in support of this mechanism. Cysteine accelerates the consumption of .NO by 2.5-fold under physiological conditions. The consumption of O2 in the presence of .NO and cysteine is increased by 2.4-fold. The reaction orders of .NO and cysteine are second and first order, respectively. The second order of reaction for .NO may result from interaction between .NO and O-2 to form peroxynitrite. In the presence of Cu,Zn-superoxide dismutase, the reaction of .NO with cysteine generates hydrogen peroxide, indicating that the reaction generates O-2. Finally, the formation of S-nitrosothiol is demonstrated in an anaerobic environment and, as predicted by the mechanism, is dependent on the presence of an electron acceptor. These results demonstrate that under physiological conditions .NO reacts directly with thiols to form S-nitrosothiol in the presence of an electron acceptor.
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Gow A, Gragerov A, Gard A, Colman DR, Lazzarini RA. Conservation of topology, but not conformation, of the proteolipid proteins of the myelin sheath. J Neurosci 1997; 17:181-9. [PMID: 8987747 PMCID: PMC6793710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The proteolipid protein gene products DM-20 and PLP are adhesive intrinsic membrane proteins that make up >/=50% of the protein in myelin and serve to stabilize compact myelin sheaths at the extracellular surfaces of apposed membrane lamellae. To identify which domains of DM-20 and PLP are positioned topologically in the extracellular space to participate in adhesion, we engineered N-glycosylation consensus sites into the hydrophilic segments and determined the extent of glycosylation. In addition, we assessed the presence of two translocation stop-transfer signals and, finally, mapped the extracellular and cytoplasmic dispositions of four antibody epitopes. We find that the topologies of DM-20 and PLP are identical, with both proteins possessing four transmembrane domains and N and C termini exposed to the cytoplasm. Consistent with this notion, DM-20 and PLP contain within their N- and C-terminal halves independent stop-transfer signals for insertion into the bilayer of the rough endoplasmic reticulum during de novo synthesis. Surprisingly, the conformation (as opposed to topology) of DM-20 and PLP may differ, which has been inferred from the divergent effects that many missense mutations have on the intracellular trafficking of these two isoforms. The 35 amino acid cytoplasmic peptide in PLP, which distinguishes this protein from DM-20, imparts a sensitivity to mutations in extracellular domains. This peptide may normally function during myelinogenesis to detect conformational changes originating across the bilayer from extracellular PLP interactions in trans and trigger intracellular events such as membrane compaction in the cytoplasmic compartment.
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Jaquet V, Gow A, Tosic M, Suchanek G, Breitschopf H, Lassmann H, Lazzarini RA, Matthieu JM. An antisense transgenic strategy to inhibit the myelin oligodendrocyte glycoprotein synthesis. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1996; 43:333-7. [PMID: 9037550 DOI: 10.1016/s0169-328x(96)00219-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To understand the function of the myelin oligodendrocyte glycoprotein (MOG), a myelin specific protein of the central nervous system, transgenic mice were produced. The transgene is a fusion gene containing 1.9 kb of murine myelin basic protein promoter, 430 bp of rat MOG cDNA in the reverse orientation and 4.5 kb of human proteolipid protein gene. In spite of high expression of antisense MOG mRNA in the oligodendrocytes, MOG synthesis was not inhibited in transgenic mice. This lack of inhibition of MOG underlines the difficulties encountered with antisense transgenic strategies.
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Gow A, Duran D, Thom SR, Ischiropoulos H. Carbon dioxide enhancement of peroxynitrite-mediated protein tyrosine nitration. Arch Biochem Biophys 1996; 333:42-8. [PMID: 8806752 DOI: 10.1006/abbi.1996.0362] [Citation(s) in RCA: 249] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Production of reactive species has been associated with tissue injury in diverse human disorders and experimental models of disease. Peroxynitrite is a strong oxidant with multiple pathways of reactivity. One protein modification reaction that may be specific to peroxynitrite is the nitration of the ortho position of tyrosine residues and nitrotyrosine has been used as a marker for peroxynitrite-mediated oxidative stress. Nitrotyrosine was formed when peroxynitrite was reacted at physiological pH with fatty acid-free bovine serum albumin or with human plasma proteins. Nitrotyrosine was not formed when proteins were incubated with nitric oxide, nitrogen dioxide, or nitric oxide plus hydrogen peroxide in the presence of ferrous iron or ferrihorseradish peroxidase. Low-molecular-weight molecules such as uric acid, ascorbate, and sulfhydryls inhibited protein tyrosine nitration in the absence of bicarbonate. Addition of bicarbonate catalytically enhanced the yield of nitration and overcame the inhibition of these antioxidants. Bicarbonate/CO2 enhanced the yield of protein nitrotyrosine in a concentration-dependent manner. Catalysis of nitration is achieved by the interaction of CO2 with the peroxynitrite anion. A mechanism is proposed involving an ONOO(O)CO- intermediate, which readily nitrates tyrosine residues in a non-radical-dependent manner. Thus, peroxynitrite nitrates tyrosine residues by a mechanism that is catalyzed by CO2 under normal physiological conditions.
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Abstract
Pelizaeus-Merzbacher disease (PMD) is a leukodystrophy linked to the proteolipid protein gene (PLP). We report a cellular basis for the distinction between two disease subtypes, classical and connatal, based on protein trafficking of the two PLP gene products (PLP and DM20). Classical PMD mutations correlate with accumulation of PLP in the ER of transfected COS-7 cells while the cognate DM20 traverses the secretory pathway to the cell surface. On the other hand, connatal PMD mutations lead to the accumulation of both mutant PLP and DM20 proteins in the ER of COS-7 cells with little of either isoform transported to the cell surface. Moreover, we show that transport-competent mutant DM20s facilitate trafficking of cognate PLPs and hence may influence disease severity.
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Gow AJ, Duran D, Malcolm S, Ischiropoulos H. Effects of peroxynitrite-induced protein modifications on tyrosine phosphorylation and degradation. FEBS Lett 1996; 385:63-6. [PMID: 8641468 DOI: 10.1016/0014-5793(96)00347-x] [Citation(s) in RCA: 339] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The ability of protein tyrosine kinases to phosphorylate a synthetic peptide was inhibited 51% by peroxynitrite-mediated nitration of tyrosine. Exposure of endothelial cells to peroxynitrite decreased the intensity of tyrosine phosphorylated proteins and increased the intensity of nitrotyrosine-containing proteins. Peroxynitrite-modified BSA was degraded by human red blood cell lysates. However, human plasma in a concentration-, time-, and temperature-dependent manner, removed the protein nitrotyrosine epitope. These results suggest that tyrosine nitration interferes with phosphorylation and targets proteins for degradation. Specific enzymatic process(es) for removing nitrotyrosine may be present in vivo.
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Tosic M, Gow A, Dolivo M, Domanska-Janik K, Lazzarini RA, Matthieu JM. Proteolipid/DM-20 proteins bearing the paralytic tremor mutation in peripheral nerves and transfected Cos-7 cells. Neurochem Res 1996; 21:423-30. [PMID: 8734435 DOI: 10.1007/bf02527706] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Paralytic tremor (Plp-pt) is a missense mutation of the myelin proteolipid gene (Plp) in rabbits. The myelin yield in the Plp-pt brain is reduced and the protein and lipid composition of central nervous system (CNS) myelin is abnormal. We studied the intracellular transport of the normal and Plp-pt mutant PLP and DM-20 in transiently transfected Cos-7 cells. While the mutant PLP accumulates in the rough endoplasmic reticulum and does not reach the plasma membrane, the spliced isoform of PLP, mutant DM-20, is normally transported to the cell surface and integrated into the membrane. Analysis of rabbit sciatic nerves revealed that concentration of peripheral nervous system (PNS) myelin proteins is normal in Plp-pt myelin. In the PNS like in the CNS, the level of Plp gene products is subnormal. But this does not affect myelination in the PNS where PLP, present in low concentration, is not a structural component of compact myelin. The normal level of Plp gene expression in Schwann cells is low and these results suggest that, in the Plp-pt PNS, Schwann cell function is not affected by the deficiency in PLP and/or the impairment of intracellular PLP transport.
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Zielinski GA, Mayewski PA, Meeker LD, Whitlow S, Twickler MS, Morrison M, Meese DA, Gow AJ, Alley RB. Response
: The GISP Ice Core Record of Volcanism Since 7000 B.C. Science 1995; 267:257-8. [PMID: 17791350 DOI: 10.1126/science.267.5195.257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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