1
|
Mersha FB, Cortes LK, Luck AN, McClung CM, Ruse CI, Taron CH, Foster JM. Computational and experimental analysis of the glycophosphatidylinositol-anchored proteome of the human parasitic nematode Brugia malayi. PLoS One 2019; 14:e0216849. [PMID: 31513600 PMCID: PMC6742230 DOI: 10.1371/journal.pone.0216849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/20/2019] [Indexed: 12/05/2022] Open
Abstract
Further characterization of essential systems in the parasitic filarial nematode Brugia malayi is needed to better understand its biology, its interaction with its hosts, and to identify critical components that can be exploited to develop novel treatments. The production of glycophosphatidylinositol-anchored proteins (GPI-APs) is essential for eukaryotic cellular and physiological function. In addition, GPI-APs perform many important roles for cells. In this study, we characterized the B. malayi GPI-anchored proteome using both computational and experimental approaches. We used bioinformatic strategies to show the presence or absence of B. malayi GPI-AP biosynthetic pathway genes and to compile a putative B. malayi GPI-AP proteome using available prediction programs. We verified these in silico analyses using proteomics to identify GPI-AP candidates prepared from the surface of intact worms and from membrane enriched extracts. Our study represents the first description of the GPI-anchored proteome in B. malayi and lays the groundwork for further exploration of this essential protein modification as a target for novel anthelmintic therapeutic strategies.
Collapse
Affiliation(s)
- Fana B. Mersha
- New England Biolabs, Ipswich MA, United States of America
| | | | - Ashley N. Luck
- New England Biolabs, Ipswich MA, United States of America
| | | | | | | | | |
Collapse
|
2
|
Assis CRD, Linhares AG, Cabrera MP, Oliveira VM, Silva KCC, Marcuschi M, Maciel Carvalho EVM, Bezerra RS, Carvalho LB. Erythrocyte acetylcholinesterase as biomarker of pesticide exposure: new and forgotten insights. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:18364-18376. [PMID: 29797194 DOI: 10.1007/s11356-018-2303-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Acetylcholinesterase (AChE) acts on the hydrolysis of acetylcholine, rapidly removing this neurotransmitter at cholinergic synapses and neuromuscular junctions as well as in neuronal growth and differentiation, modulation of cell adhesion ("electrotactins") and aryl-acylamidase activity (AAA). This enzyme is also found in erythrocyte, as 160 kDa dimer that anchors to the plasma membrane via glycophosphatidylinositol. The function of this enzyme in erythrocytes has not yet been elucidated; however, it is suspected to participate in cell-to-cell interactions. Here, a review on erythrocyte AChE characteristics and use as biomarker for organophosphorus and carbamate insecticides is presented since it is the first specific target/barrier of the action of these pesticides, besides plasma butyrylcholinesterase (BChE). However, some past and current methods have disadvantages: (a) not discriminating the activities of AChE and BChE; (b) low accuracy due to interference of hemoglobin in whole blood samples. On the other hand, extraction methods of hemoglobin-free erythrocyte AChE allows: (a) the freezing and transporting of samples; (b) samples free of colorimetric interference; (c) data from only erythrocyte AChE activity; (d) erythrocyte AChE specific activity presents higher correlation with the central nervous system AChE than other peripheral ChEs; (e) slow spontaneous regeneration against anti-ChEs agents of AChE in comparison to BChE, thus increasing the chances of detecting such compounds following longer interval after exposure. As monitoring perspectives, hemoglobin-free methodologies may be promising alternatives to assess the degree of exposure since they are not influenced by this interfering agent.
Collapse
Affiliation(s)
- Caio R D Assis
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil.
| | - Amanda G Linhares
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil
| | - Mariana P Cabrera
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil
| | - Vagne M Oliveira
- Laboratório de Tecnologia de Produtos Bioativos, Departamento de Morfologia e Fisiologia Animal, DMFA, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil
| | - Kaline C C Silva
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil
- Universidade Estadual da Bahia, Paulo Afonso, Bahia, Brazil
| | - Marina Marcuschi
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil
| | - Elba V M Maciel Carvalho
- Laboratório de Glicoproteínas, Departamento de Bioquímica, Universidade Federal de Pernambuco, Recife, PE, Brazil
| | - Ranilson S Bezerra
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil
| | - Luiz B Carvalho
- Laboratório de Enzimologia - LABENZ, Departamento de Bioquímica and Laboratório de Imunopatologia Keizo Asami - LIKA, Universidade Federal de Pernambuco, Recife, Pernambuco, 50670-901, Brazil
| |
Collapse
|
3
|
Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM. Alzheimer's disease: Targeting the Cholinergic System. Curr Neuropharmacol 2016; 14:101-15. [PMID: 26813123 PMCID: PMC4787279 DOI: 10.2174/1570159x13666150716165726] [Citation(s) in RCA: 855] [Impact Index Per Article: 106.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 07/01/2015] [Accepted: 07/14/2015] [Indexed: 12/16/2022] Open
Abstract
Acetylcholine (ACh) has a crucial role in the peripheral and central nervous
systems. The enzyme choline acetyltransferase (ChAT) is responsible for
synthesizing ACh from acetyl-CoA and choline in the cytoplasm and the vesicular
acetylcholine transporter (VAChT) uptakes the neurotransmitter into synaptic
vesicles. Following depolarization, ACh undergoes exocytosis reaching the
synaptic cleft, where it can bind its receptors, including muscarinic and
nicotinic receptors. ACh present at the synaptic cleft is promptly hydrolyzed by
the enzyme acetylcholinesterase (AChE), forming acetate and choline, which is
recycled into the presynaptic nerve terminal by the high-affinity choline
transporter (CHT1). Cholinergic neurons located in the basal forebrain,
including the neurons that form the nucleus basalis of Meynert, are severely
lost in Alzheimer’s disease (AD). AD is the most ordinary cause of dementia
affecting 25 million people worldwide. The hallmarks of the disease are the
accumulation of neurofibrillary tangles and amyloid plaques. However, there is
no real correlation between levels of cortical plaques and AD-related cognitive
impairment. Nevertheless, synaptic loss is the principal correlate of disease
progression and loss of cholinergic neurons contributes to memory and attention
deficits. Thus, drugs that act on the cholinergic system represent a promising
option to treat AD patients.
Collapse
Affiliation(s)
| | | | | | - Fabiola M Ribeiro
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
| |
Collapse
|
4
|
Yoon M, Kedderis GL, Yan GZ, Clewell HJ. Use of in vitro data in developing a physiologically based pharmacokinetic model: Carbaryl as a case study. Toxicology 2014; 332:52-66. [PMID: 24863738 DOI: 10.1016/j.tox.2014.05.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 04/02/2014] [Accepted: 05/18/2014] [Indexed: 12/14/2022]
Abstract
In vitro-derived information has been increasingly used to support and improve human health risk assessment for exposure to chemicals. Physiologically based pharmacokinetic (PBPK) modeling is a key component in the movement toward in vitro-based risk assessment, providing a tool to integrate diverse experimental data and mechanistic information to relate in vitro effective concentrations to equivalent human exposures. One of the challenges, however, in the use of PBPK models for this purpose has been the need for extensive chemical-specific parameters. With the remarkable advances in in vitro methodologies in recent years, in vitro-derived parameters can now be easily incorporated into PBPK models. In this study we demonstrate an in vitro data based parameterization approach to develop a physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) model, using carbaryl as a case study. In vitro experiments were performed to provide the chemical-specific pharmacokinetic (PK) and pharmacodynamic (PD) parameters for carbaryl in the PBPK model for this compound. Metabolic clearance and cholinesterase (ChE) interaction parameters for carbaryl were measured in rat and human tissues. These in vitro PK and PD data were extrapolated to parameters in the whole body PBPK model using biologically appropriate scaling. The PBPK model was then used to predict the kinetics and ChE inhibition dynamics of carbaryl in vivo. This case study with carbaryl provides a reasonably successful example of utilizing the in vitro to in vivo extrapolation (IVIVE) approach for PBPK model development. This approach can be applied to other carbamates with an anticholinesterase mode of action as well as to environmental chemicals in general with further refinement of the current shortcomings in the approach. It will contribute to minimizing the need for in vivo human data for PBPK model parameterization and evaluation in human risk assessments.
Collapse
Affiliation(s)
- Miyoung Yoon
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.
| | | | - Grace Zhixia Yan
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.
| | - Harvey J Clewell
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.
| |
Collapse
|
5
|
Pezzementi L, Nachon F, Chatonnet A. Evolution of acetylcholinesterase and butyrylcholinesterase in the vertebrates: an atypical butyrylcholinesterase from the Medaka Oryzias latipes. PLoS One 2011; 6:e17396. [PMID: 21364766 PMCID: PMC3045457 DOI: 10.1371/journal.pone.0017396] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 02/02/2011] [Indexed: 12/16/2022] Open
Abstract
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are thought to be the result of a gene duplication event early in vertebrate evolution. To learn more about the evolution of these enzymes, we expressed in vitro, characterized, and modeled a recombinant cholinesterase (ChE) from a teleost, the medaka Oryzias latipes. In addition to AChE, O. latipes has a ChE that is different from either vertebrate AChE or BChE, which we are classifying as an atypical BChE, and which may resemble a transitional form between the two. Of the fourteen aromatic amino acids in the catalytic gorge of vertebrate AChE, ten are conserved in the atypical BChE of O. latipes; by contrast, only eight are conserved in vertebrate BChE. Notably, the atypical BChE has one phenylalanine in its acyl pocket, while AChE has two and BChE none. These substitutions could account for the intermediate nature of this atypical BChE. Molecular modeling supports this proposal. The atypical BChE hydrolyzes acetylthiocholine (ATCh) and propionylthiocholine (PTCh) preferentially but butyrylthiocholine (BTCh) to a considerable extent, which is different from the substrate specificity of AChE or BChE. The enzyme shows substrate inhibition with the two smaller substrates but not with the larger substrate BTCh. In comparison, AChE exhibits substrate inhibition, while BChE does not, but may instead show substrate activation. The atypical BChE from O. latipes also shows a mixed pattern of inhibition. It is effectively inhibited by physostigmine, typical of all ChEs. However, although the atypical BChE is efficiently inhibited by the BChE-specific inhibitor ethopropazine, it is not by another BChE inhibitor, iso-OMPA, nor by the AChE-specific inhibitor BW284c51. The atypical BChE is found as a glycophosphatidylinositol-anchored (GPI-anchored) amphiphilic dimer (G(2) (a)), which is unusual for any BChE. We classify the enzyme as an atypical BChE and discuss its implications for the evolution of AChE and BChE and for ecotoxicology.
Collapse
Affiliation(s)
- Leo Pezzementi
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Florian Nachon
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, Antenne de la Tronche, La Tronche, France
| | - Arnaud Chatonnet
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 866, Montpellier, France
- Université Montpellier 1, Montpellier, France
- Université Montpellier 2, Montpellier, France
| |
Collapse
|
6
|
De Lederkremer RM, Agusti R, Docampo R. Inositolphosphoceramide metabolism in Trypanosoma cruzi as compared with other trypanosomatids. J Eukaryot Microbiol 2011; 58:79-87. [PMID: 21332877 DOI: 10.1111/j.1550-7408.2011.00533.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chagas disease is caused by Trypanosoma cruzi and is endemic to North, Central and South American countries. Current therapy against this disease is only partially effective and produces adverse side effects. Studies on the metabolic pathways of T. cruzi, in particular those with no equivalent in mammalian cells, might identify targets for the development of new drugs. Ceramide is metabolized to inositolphosphoceramide (IPC) in T. cruzi and other kinetoplastid protists whereas in mammals it is mainly incorporated into sphingomyelin. In T. cruzi, in contrast to Trypanosoma brucei and Leishmania spp., IPC functions as lipid anchor constituent of glycoproteins and free glycosylinositolphospholipids (GIPLs). Inhibition of IPC and GIPLs biosynthesis impairs differentiation of trypomastigotes into the intracellular amastigote forms. The gene encoding IPC synthase in T. cruzi has been identified and the enzyme has been expressed in a cell-free system. The enzyme involved in IPC degradation and the remodelases responsible for the incorporation of ceramide into free GIPLs or into the glycosylphosphatidylinositols anchoring glycoproteins, and in fatty acid modifications of these molecules of T. cruzi have been understudied. Inositolphosphoceramide metabolism and remodeling could be exploited as targets for Chagas disease chemotherapy.
Collapse
Affiliation(s)
- Rosa M De Lederkremer
- CHIDECAR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | | | | |
Collapse
|
7
|
Ye W, Gong X, Xie J, Wu J, Zhang X, Ouyang Q, Zhao X, Shi Y, Zhang X. AChE deficiency or inhibition decreases apoptosis and p53 expression and protects renal function after ischemia/reperfusion. Apoptosis 2010; 15:474-87. [PMID: 20054652 DOI: 10.1007/s10495-009-0438-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
We recently reported that the expression of the synaptic form of acetylcholinesterase (AChE) is induced during apoptosis in various cell types in vitro. Here, we provide evidence to confirm that AChE is expressed during ischemia-reperfusion (I/R)-induced apoptosis in vivo. Renal I/R is a major cause of acute renal failure (ARF), resulting in injury and the eventual death of renal cells due to a combination of apoptosis and necrosis. Using AChE-deficient mice and AChE inhibitors, we investigated whether AChE deficiency or inhibition can protect against apoptosis caused by I/R in a murine kidney model. Unilateral clamping of renal pedicles for 90 min followed by reperfusion for 24 h caused significant renal dysfunction and injury. Both genetic AChE deficiency and chemical inhibition of AChE (provided by huperzine A, tacrine and donepezil) significantly reduced the biochemical and histological evidence of renal dysfunction following I/R. Activation of caspases-8, -9, -12, and -3 in vivo were prevented and associated with reduced levels of cell apoptosis and cell death. A further investigation also confirmed that AChE deficiency down-regulated p53 induction and phosphorylation at serine-15, and decreased the Bax/Bcl-2 ratio during I/R. In conclusion, our study demonstrates that AChE may be a pro-apoptotic factor and the inhibition of AChE reduces renal I/R injury. These findings suggest that AChE inhibitors may represent a therapeutic strategy for protection against ischemic acute renal failure.
Collapse
Affiliation(s)
- Weiyuan Ye
- Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, China.
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Affiliation(s)
- Rosa M de Lederkremer
- Departamento de Quimica Organica, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina
| | | |
Collapse
|
9
|
Salto ML, Bertello LE, Vieira M, Docampo R, Moreno SNJ, de Lederkremer RM. Formation and remodeling of inositolphosphoceramide during differentiation of Trypanosoma cruzi from trypomastigote to amastigote. EUKARYOTIC CELL 2003; 2:756-68. [PMID: 12912895 PMCID: PMC178363 DOI: 10.1128/ec.2.4.756-768.2003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Differentiation of Trypanosoma cruzi trypomastigotes to amastigotes inside myoblasts or in vitro, at low extracellular pH, in the presence of [(3)H]palmitic acid or [(3)H]inositol revealed differential labeling of inositolphosphoceramide and phosphatidylinositol, suggesting that a remodeling process takes place in both lipids. Using (3)H-labeled inositolphosphoceramide and phosphatidylinositol as substrates, we demonstrated the association of at least five enzymatic activities with the membranes of amastigotes and trypomastigotes. These included phospholipase A(1), phospholipase A(2), inositolphosphoceramide-fatty acid hydrolase, acyltransferase, and a phospholipase C releasing either ceramide or a glycerolipid from the inositolphospholipids. These enzymes may be acting in remodeling reactions leading to the anchor of mature glycoproteins or glycoinositolphospholipids and helping in the transformation of the plasma membrane, a necessary step in the differentiation of slender trypomastigotes to round amastigotes. Synthesis of inositolphosphoceramide and particularly of glycoinositolphospholipids was inhibited by aureobasidin A, a known inhibitor of fungal inositolphosphoceramide synthases. The antibiotic impaired the differentiation of trypomastigotes at acidic pH, as indicated by an increased appearance of intermediate forms and a decreased expression of the Ssp4 glycoprotein, a characteristic marker of amastigote forms. Aureobasidin A was also toxic to differentiating trypomastigotes at acidic pH but not to trypomastigotes maintained at neutral pH. Our data suggest that inositolphosphoceramide is implicated in T. cruzi differentiation and that its metabolism could provide important targets for the development of antiparasitic therapies.
Collapse
Affiliation(s)
- Maria Laura Salto
- Laboratory of Molecular Parasitology, Department of Pathobiology and Center for Zoonoses Research, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, 61802, USA
| | | | | | | | | | | |
Collapse
|
10
|
Nagao M, Takatori T, Maeno Y, Isobe I, Koyama H, Tsuchimochi T. Development of forensic diagnosis of acute sarin poisoning. Leg Med (Tokyo) 2003; 5 Suppl 1:S34-40. [PMID: 12935549 DOI: 10.1016/s1344-6223(02)00086-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
On March 20, 1995, the Tokyo subway system was subjected to a horrifying terrorist attack with sarin gas (isopropyl methylphosphonofluoridate) that left 12 persons dead and over 5000 injured. In order to diagnose the definite cause of death of the victims, a new method was developed to detect sarin hydrolysis products in the erythrocytes and formalin-fixed cerebella from four victims of sarin poisoning. Sarin-bound acetylcholinesterase (AChE) was solubilized from the specimens of sarin victims and digested with trypsin. The sarin hydrolysis products bound to AChE were released by alkaline phosphatase digestion. The digested sarin hydrolysis products were subjected to trimethylsilyl derivatization and detected by gas chromatography-mass spectrometry. Sarin hydrolysis products were detected in all sarin poisoning victims.
Collapse
Affiliation(s)
- Masataka Nagao
- Department of Forensic Medical Science, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-ku, Nagoya 467-8601, Japan.
| | | | | | | | | | | |
Collapse
|
11
|
Kristiansen S, Richter EA. GLUT4-containing vesicles are released from membranes by phospholipase D cleavage of a GPI anchor. Am J Physiol Endocrinol Metab 2002; 283:E374-82. [PMID: 12110545 DOI: 10.1152/ajpendo.00441.2001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously developed a cell-free assay from rat skeletal muscle that displayed in vitro glucose transporter 4 (GLUT4) transfer from large to small membrane structures by the addition of a cytosolic protein fraction. By combining protein fractionation and the in vitro GLUT4 transfer assay, we have purified a glycosylphosphatidylinositol (GPI) phospholipase D (PLD) that induces transfer of GLUT4 from small to large membranes. The in vitro GLUT4 transfer was activated and inhibited by suramin and 1,10-phenanthroline (an activator and an inhibitor of GPI-PLD activity, respectively). Furthermore, upon purification of the GLUT4 transporter protein, the protein displayed an elution profile in which the molecular mass was related to the charge, suggesting the presence or absence of phosphate. Second, by photoaffinity labeling of the purified GLUT4 with 3-(trifluoromethyl)-3-(m-[(125)I]iodopenyl)diazirine, both labeled phosphatidylethanolamine and fatty acids (constituents of a GPI link) were recovered. Third, by using phase transition of Triton X-114, the purified GLUT4 was found to be partly detergent resistant, which is a known characteristic of GPI-linked proteins. Fourth, the purified GLUT4 protein was recognized by an antibody raised specifically against GPI links. In conclusion, GLUT4-containing vesicles may be released from a membrane compartment by action of a GPI-PLD.
Collapse
Affiliation(s)
- Søren Kristiansen
- Copenhagen Muscle Reseach Centre, Department of Human Physiology, Institute of Exercise and Sports Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | | |
Collapse
|
12
|
Simmons PJ, Zannettino AC, Harrison-Findik D, Swart B, Tomlinson S, Hill B, Javni JA. A novel epitope of CD59 expressed by primitive human hematopoietic progenitors. Exp Hematol 2001; 29:1474-83. [PMID: 11750107 DOI: 10.1016/s0301-472x(01)00745-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The aim of this study was to determine the identity of the cell surface molecule on primitive hematopoietic cells recognized by monoclonal antibody HCC-1. MATERIALS AND METHODS Screening of a cDNA expression library prepared from human bone marrow stromal cells with HCC-1 yielded a single cDNA, which when expressed in FDCP-1 cells, resulted in the specific acquisition of HCC-1 binding. The cDNA demonstrated complete identity with CD59, a phosphoinositol glycan-linked membrane protein that protects cells against autologous complement attack. The ubiquitous expression of CD59 is in marked contrast to the restricted reactivity of HCC-1. Studies were performed to examine the basis for the novel specificity of HCC-1 for CD59. The epitope on CD59 identified by HCC-1 was mapped using a series of rat/human CD59 chimeric proteins. Immunoprecipitation analyses were performed to determine whether CD59 associates with other membrane proteins. RESULTS Mutagenesis of Asn18 did not alter the binding of HCC-1 to CD59, suggesting that N-linked carbohydrates are not responsible for the binding specificity of HCC-1. The epitope for HCC-1 was shown to differ from that identified by previously described CD59 antibodies, encompassing residues A31, L33, R55, and L59. An 80 kDa protein co-immunoprecipitated with CD59 in the HCC-1(-) cell line HL-60 but not in HCC-1(+) K562 cells. CONCLUSION Collectively, these data support the hypothesis that the unique specificity of HCC-1 for CD59 is due in part to recognition of a novel epitope, which is masked as a result of association with an as yet unidentified 80 kDa protein.
Collapse
Affiliation(s)
- P J Simmons
- Stem Cell Laboratory, The Peter MacCallum Cancer Institute, East Melbourne, Victoria, Australia.
| | | | | | | | | | | | | |
Collapse
|
13
|
Singh BN, BonDurant RH, Campero CM, Corbeil LB. Immunological and biochemical analysis of glycosylated surface antigens and lipophosphoglycan of Tritrichomonas foetus. J Parasitol 2001; 87:770-7. [PMID: 11534640 DOI: 10.1645/0022-3395(2001)087[0770:iabaog]2.0.co;2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Immunoaffinity-purified TF1.17 adhesin antigen was compared biochemically and antigenically to Tritrichomonas foetus (TF) lipophosphoglycan (LPG) and a soluble glycosylated antigen (SGA) released from T. foetus and implicated in pathogenesis and immunity. The monoclonal antibodies (Mabs TF1.15 and TF1.17) specific for a glycosylated TF1.17 antigen were previously shown to prevent adhesion of the T. foetus parasites to bovine vaginal epithelial cells and to mediate killing by bovine complement. SGA was isolated from T. foetus-conditioned buffer and purified by octyl-Sepharose hydrophobic column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of SGA showed a major SGA1 component (approximately 190 kDa) and a minor SGA2 component (50-70 kDa), which migrated close to TF-LPG and TF1.17. The carbohydrate and lipid compositional analyses of affinity-purified TF1.17 and SGA2 by high-performance liquid chromatography (HPLC) and gas-liquid chromatography revealed the presence of monosaccharides and fatty acids as found in TF-LPG. All antigens contained terminal fucose as determined by alpha-fucosidase digestion followed by HPLC. ELISA and western blots were used to further characterize these glycosylated antigens and to analyze their relationships. The Mabs TF1.15 and TF1.17 reacted very strongly to TF-LPG and SGA2. as well as TF1.17 antigen, indicating that these molecules share common epitopes. These Mabs did not react with the SGA1 component either in ELISA and western blot analyses. Also, the monosaccharide composition of SGA1 was very different from the other three antigen, suggesting SGA1 was different from LPG, SGA2 and TF1.17. Although LPG reacted with Mabs to native TF1.17 antigen, LPG did not induce an immune response in cattle with the same route and adjuvant used to produce strong antibody responses to the native antigen. The latter response suggests that the tightly bound peptide present in the immunoaffinity-purified antigen is necessary for induction of a response to (an) epitope(s) in TF-LPG and TF1.17. Furthermore, vaginal fluid from T. foetus-infected heifers and serum from a cow with a T. foetus-associated pyometra recognized both TF1.17 and TF-LPG in western blots. These results suggest that T. foetus LPG and SGA2 are related to TF1.17 antigen, which was previously shown to play an important role in the pathogenesis and host response in bovine trichomoniasis.
Collapse
Affiliation(s)
- B N Singh
- Department of Biochemistry and Molecular Biology, SUNY UpState Medical University, Syracuse, New York 13210, USA
| | | | | | | |
Collapse
|
14
|
Nelson KL, Buckley JT. Channel formation by the glycosylphosphatidylinositol-anchored protein binding toxin aerolysin is not promoted by lipid rafts. J Biol Chem 2000; 275:19839-43. [PMID: 10770947 DOI: 10.1074/jbc.m002785200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycosylphosphatidylinositol-anchored proteins may be concentrated in membrane microdomains (lipid rafts) that are also enriched in cholesterol and sphingolipids. The glycosyl anchor of these proteins is a specific, high affinity receptor for the channel-forming protein aerolysin. We wished to determine if the presence of rafts promotes the activity of aerolysin. Treatment of T lymphocytes with methyl-beta-cyclodextrin, which destroys lipid rafts by sequestering cholesterol, had no measurable effect on the sensitivity of the cells to aerolysin; nor did similar treatment of erythrocytes decrease the rate at which they were lysed by the toxin. We also studied the rate of aerolysin-induced channel formation in liposomes containing glycosylphosphatidylinositol-anchored placental alkaline phosphatase, which we show is a receptor for aerolysin. In liposomes containing sphingolipids as well as glycerophospholipids and cholesterol, most of the enzyme was Triton X-100-insoluble, indicating that it was localized in rafts, whereas in liposomes prepared without sphingolipids, all of the enzyme was soluble. Aerolysin was no more active against liposomes containing rafts than against those that did not. We conclude that lipid rafts do not promote channel formation by aerolysin.
Collapse
Affiliation(s)
- K L Nelson
- Department of Biochemistry and Microbiology, University of Victoria, Box 3055, Victoria, British Columbia V8W 3P6, Canada
| | | |
Collapse
|
15
|
Nagarajan S, Selvaraj P. Expression and characterization of glycolipid-anchored B7-1 (CD80) from baculovirus-infected insect cells: protein transfer onto tumor cells. Protein Expr Purif 1999; 17:273-81. [PMID: 10545276 DOI: 10.1006/prep.1999.1130] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tumor cells can be modified to express immunostimulatory molecules such as B7-1 by protein transfer using purified glycosylphosphatidylinositol-anchored B7-1 (GPI-B7-1). In this study recombinant baculovirus encoding GPI-B7-1 (vBacB7-1(GPI)) was established to obtain large quantities of purified GPI-B7-1 to modify tumor cells by protein transfer. vBacB7-1(GPI)-infected insect cells showed high-level cell surface expression of GPI-B7-1 that was susceptible to PIPLC treatment. GPI-B7-1 expressed in insect cells (Bac-GPI-B7-1) mediated T cell proliferation, indicating that the GPI-B7-1 retains costimulatory activity. Moreover, Bac-GPI-B7-1 was completely solubilized in Triton X-100 at 4 degrees C compared to 22% solubilization of GPI-B7-1 expressed in CHOK1 cells, suggesting that GPI-anchored proteins expressed in insect cells may not be clustered into the detergent-insoluble fraction. SDS-PAGE analysis of Bac-GPI-B7-1 showed faster mobility (45 kDa) compared to GPI-B7-1 from CHOK1 (68 kDa) and this difference may be due to a difference in glycosylation. Cell binding assays showed that immunoaffinity-purified Bac-GPI-B7-1 retained its functional ability to bind CD28(+) cells. Moreover, when human tumor cells were incubated with this functionally active purified GPI-B7-1, an efficient transfer of B7-1 onto tumor cells was observed. These results demonstrate that GPI-B7-1 can be expressed in insect cells in a functionally active form and can be used to modify tumor cells for immunotherapeutic applications.
Collapse
Affiliation(s)
- S Nagarajan
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, 30322, USA
| | | |
Collapse
|
16
|
Ferguson MA, Brimacombe JS, Brown JR, Crossman A, Dix A, Field RA, Güther ML, Milne KG, Sharma DK, Smith TK. The GPI biosynthetic pathway as a therapeutic target for African sleeping sickness. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1455:327-40. [PMID: 10571022 DOI: 10.1016/s0925-4439(99)00058-7] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
African sleeping sickness is a debilitating and often fatal disease caused by tsetse fly transmitted African trypanosomes. These extracellular protozoan parasites survive in the human bloodstream by virtue of a dense cell surface coat made of variant surface glycoprotein. The parasites have a repertoire of several hundred immunologically distinct variant surface glycoproteins and they evade the host immune response by antigenic variation. All variant surface glycoproteins are anchored to the plasma membrane via glycosylphosphatidylinositol membrane anchors and compounds that inhibit the assembly or transfer of these anchors could have trypanocidal potential. This article compares glycosylphosphatidylinositol biosynthesis in African trypanosomes and mammalian cells and identifies several steps that could be targets for the development of parasite-specific therapeutic agents.
Collapse
Affiliation(s)
- M A Ferguson
- Department of Biochemistry, University of Dundee, UK.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Mallender WD, Szegletes T, Rosenberry TL. Organophosphorylation of acetylcholinesterase in the presence of peripheral site ligands. Distinct effects of propidium and fasciculin. J Biol Chem 1999; 274:8491-9. [PMID: 10085081 DOI: 10.1074/jbc.274.13.8491] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Structural analysis of acetylcholinesterase (AChE) has revealed two sites of ligand interaction in the active site gorge: an acylation site at the base of the gorge and a peripheral site at its mouth. A goal of our studies is to understand how ligand binding to the peripheral site alters the reactivity of substrates and organophosphates at the acylation site. Kinetic rate constants were determined for the phosphorylation of AChE by two fluorogenic organophosphates, 7-[(diethoxyphosphoryl)oxy]-1-methylquinolinium iodide (DEPQ) and 7-[(methylethoxyphosphonyl)oxy]-4-methylcoumarin (EMPC), by monitoring release of the fluorescent leaving group. Rate constants obtained with human erythrocyte AChE were in good agreement with those obtained for recombinant human AChE produced from a high level Drosophila S2 cell expression system. First-order rate constants kOP were 1,600 +/- 300 min-1 for DEPQ and 150 +/- 11 min-1 for EMPC, and second-order rate constants kOP/KOP were 193 +/- 13 microM-1 min-1 for DEPQ and 0.7-1.0 +/- 0.1 microM-1 min-1 for EMPC. Binding of the small ligand propidium to the AChE peripheral site decreased kOP/KOP by factors of 2-20 for these organophosphates. Such modest inhibitory effects are consistent with our recently proposed steric blockade model (Szegletes, T., Mallender, W. D., and Rosenberry, T. L. (1998) Biochemistry 37, 4206-4216). Moreover, the binding of propidium resulted in a clear increase in kOP for EMPC, suggesting that molecular or electronic strain caused by the proximity of propidium to EMPC in the ternary complex may promote phosphorylation. In contrast, the binding of the polypeptide neurotoxin fasciculin to the peripheral site of AChE dramatically decreased phosphorylation rate constants. Values of kOP/KOP were decreased by factors of 10(3) to 10(5), and kOP was decreased by factors of 300-4,000. Such pronounced inhibition suggested a conformational change in the acylation site induced by fasciculin binding. As a note of caution to other investigators, measurements of phosphorylation of the fasciculin-AChE complex by AChE inactivation gave misleading rate constants because a small fraction of the AChE was resistant to inhibition by fasciculin.
Collapse
Affiliation(s)
- W D Mallender
- Department of Pharmacology, Mayo Foundation for Medical Education and Research, and the Department of Research, Mayo Clinic Jacksonville, Jacksonville, Florida 32224, USA
| | | | | |
Collapse
|
18
|
Worby CA, Vega QC, Chao HH, Seasholtz AF, Thompson RC, Dixon JE. Identification and characterization of GFRalpha-3, a novel Co-receptor belonging to the glial cell line-derived neurotrophic receptor family. J Biol Chem 1998; 273:3502-8. [PMID: 9452475 DOI: 10.1074/jbc.273.6.3502] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A new family of neuronal survival factors comprised of glial cell line-derived neurotrophic factor (GDNF) and neurturin has recently been described (Kotzbauer, P. T., Lampe, P. A., Heuckeroth, R. O., Golden, J. P., Creedon, D. J., Johnson, E. M., Jr., and Milbrandt, J. (1997) Nature 384, 467-470). These molecules, which are related to transforming growth factor-beta, are important in embryogenesis and in the survival of distinct neuronal populations. These molecules signal through a novel receptor system that includes the Ret receptor tyrosine kinase, a ligand (i.e. GDNF or neurturin), and an accessory glycosyl-phosphatidylinositol-linked molecule that is responsible for high affinity binding of the ligand. Two accessory molecules denoted GDNF family receptor 1 and 2 (GFRalpha-1 and GFRalpha-2) have been described that function in GDNF and neurturin signaling complexes. We have identified a novel co-receptor belonging to this family based on similarity to GFRalpha-1, which we have named GFRalpha-3. GFRalpha-3 displays 33% amino acid identity with GFRalpha-1 and 36% identity with GFRalpha-2. Despite the similarity of GFRalpha-3 to GFRalpha-1 and GFRalpha-2, it is unable to activate Ret in conjunction with GDNF, suggesting that there are likely additional undiscovered ligands and/or Ret-like receptors to be identified. GFRalpha-3 is anchored to the cell membrane by a phosphatidylinositol-specific phospholipase C-resistant glycosyl-phosphatidylinositol linkage. GFRalpha-3 is highly expressed by embryonic day 11 but is not appreciably expressed in the adult mouse. In situ hybridization analyses demonstrate that GFRalpha-3 is located in dorsal root ganglia and the superior cervical sympathetic ganglion. Comparison of the expression patterns of GFRalpha-3 and Ret suggests that these molecules could form a receptor pair and interact with GDNF family members to play unique roles in development.
Collapse
Affiliation(s)
- C A Worby
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA
| | | | | | | | | | | |
Collapse
|
19
|
Diep DB, Nelson KL, Raja SM, Pleshak EN, Buckley JT. Glycosylphosphatidylinositol anchors of membrane glycoproteins are binding determinants for the channel-forming toxin aerolysin. J Biol Chem 1998; 273:2355-60. [PMID: 9442081 DOI: 10.1074/jbc.273.4.2355] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cells that are sensitive to the channel-forming toxin aerolysin contain surface glycoproteins that bind the toxin with high affinity. Here we show that a common feature of aerolysin receptors is the presence of a glycosylphosphatidylinositol anchor, and we present evidence that the anchor itself is an essential part of the toxin binding determinant. The glycosylphosphatidylinositol (GPI)-anchored T-lymphocyte protein Thy-1 is an example of a protein that acts as an aerolysin receptor. This protein retained its ability to bind aerolysin when it was expressed in Chinese hamster ovary cells, but could not bind the toxin when expressed in Escherichia coli, where the GPI anchor is absent. An unrelated GPI-anchored protein, the variant surface glycoprotein of trypanosomes, was shown to bind aerolysin with similar affinity to Thy-1, and this binding ability was significantly reduced when the anchor was removed chemically. Cathepsin D, a protein with no affinity for aerolysin, was converted to an aerolysin binding form when it was expressed as a GPI-anchored hybrid in COS cells. Not all GPI-anchored proteins bind aerolysin. In some cases this may be due to differences in the structure of the anchor itself. Thus the GPI-anchored proteins procyclin of Trypanosoma congolense and gp63 of Leishmania major did not bind aerolysin, but when gp63 was expressed with a mammalian GPI anchor in Chinese hamster ovary cells, it bound the toxin.
Collapse
Affiliation(s)
- D B Diep
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
| | | | | | | | | |
Collapse
|
20
|
Schroeder RJ, Ahmed SN, Zhu Y, London E, Brown DA. Cholesterol and sphingolipid enhance the Triton X-100 insolubility of glycosylphosphatidylinositol-anchored proteins by promoting the formation of detergent-insoluble ordered membrane domains. J Biol Chem 1998; 273:1150-7. [PMID: 9422781 DOI: 10.1074/jbc.273.2.1150] [Citation(s) in RCA: 348] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins can be isolated from both cells and sphingolipid and cholesterol-rich liposomes (SCRLs) in association with detergent-insoluble membranes. We found previously that detergent insolubility of lipids was characteristic of phases in which lipid acyl chains are ordered. We presented evidence that GPI-anchored proteins are insoluble because they associate with cholesterol and sphingolipid-rich lipid domains with properties similar to the liquid-ordered phase. Here, this model was tested by a variety of approaches. First, we demonstrated that saponin, which removes cholesterol from cell membranes and allows solubilization of GPI-anchored proteins by Triton X-100, had the same effect on the GPI-anchored protein alkaline phosphatase (PLAP) in SCRLs of appropriate lipid composition. The similarity of saponin action in cells and simple liposomes suggests that the compound disrupts protein-lipid interactions. However, direct interactions between PLAP and cholesterol were not needed for insolubility, because the protein was also insoluble in cholesterol-free liposomes containing lipid in an ordered phase. Instead, cholesterol acted by greatly enhancing the formation of a detergent-insoluble phase by sphingolipids, which have a tendency to form ordered phases. We propose that saponin solubilizes GPI-anchored proteins because the lipid composition of cell membranes (and the SCRLs used above) supports ordered phase formation in the presence but not the absence of cholesterol. Supporting this model, saponin did not promote Triton X-100 solubilization of PLAP in SCRLs with sphingolipid levels high enough to allow ordered phase formation in the absence of cholesterol. We also showed that two additional GPI-anchored proteins are detergent-insoluble in SCRLs and that detergent does not artifactually create ordered domains or cause components of solubilized membranes to associate with detergent-resistant membranes present in separate bilayers in the same lysate. We conclude that the ordered domain model explains the behavior of detergent-resistant membranes in liposomes and cells.
Collapse
Affiliation(s)
- R J Schroeder
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, New York 11794-5215, USA
| | | | | | | | | |
Collapse
|
21
|
Grigg ME, Tang L, Hussein AS, Selkirk ME. Purification and properties of monomeric (G1) forms of acetylcholinesterase secreted by Nippostrongylus brasiliensis. Mol Biochem Parasitol 1997; 90:513-24. [PMID: 9476798 DOI: 10.1016/s0166-6851(97)00202-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Acetylcholinesterase (AChE) activity secreted by Nippostrongylus brasiliensis was resolved by sucrose density centrifugation and gel permeation chromatography in single peaks estimated at 4.3 S and 60-85 kDa, respectively. Sedimentation was unaffected by the inclusion of detergent. AChE was purified by affinity chromatography on 9-[Nbeta-(epsilon-aminocaproyl)-beta-aminopropylamino]-acridinium bromide hydrobromide-coupled sepharose 4B. Three forms of the enzyme (A, B and C) were distinguished by non-denaturating polyacrylamide gel electrophoresis, and displayed apparent masses of 74, 69 and 71 kDa respectively when resolved by SDS-PAGE. All three isoforms showed a preference for acetylthiocholine (ASCh) as substrate. They were highly sensitive to inhibition by the AChE-specific inhibitor bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide, with inhibitor concentration reducing initial activity by 50% (IC50) between 0.1 and 0.8 microM, but activity was unaffected by tetramonoisopropylpyrophosphortetramide (iso-OMPA) at concentrations up to 10 mM. We conclude that the secreted enzymes are authentic AChEs of hydrophilic monomeric (G1) form and broadly similar properties, but which can be distinguished by molecular mass, inhibitor sensitivities and the degree of excess substrate inhibition.
Collapse
Affiliation(s)
- M E Grigg
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK
| | | | | | | |
Collapse
|
22
|
Niketić V, Tomasević N, Nikolić M. Covalent glycoinositolphospholipid binding to hemoglobin: a new post-translational modification of Hb occurring in hyperinsulinism with concomitant hypoglycemia. Biochem Biophys Res Commun 1997; 239:435-8. [PMID: 9344847 DOI: 10.1006/bbrc.1997.7362] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this work a novel hitherto unrecognised minor hemoglobin (Hb) fraction, which we detected previously in hemolysates of erythrocytes exposed to a high concentration of insulin under hypoglycemic conditions, both in vivo and in vitro, is analysed. The modification of Hb in HbA1x was shown to be due the addition of glycoinositolphospholipid (GPI) to the C termini of both beta polypeptide chains. A structurally related minor Hb fraction was identified in erythrocytes exposed in vitro to insulin-mimetic agent, trypsin. To our knowledge this is the first demonstration of such a modification of Hb, as well as the first demonstration of post-translational GPI binding to proteins in response to insulin. The mechanism proposed for GPI-Hb formation is briefly described.
Collapse
Affiliation(s)
- V Niketić
- Department of Chemistry, University of Belgrade, Yugoslavia.
| | | | | |
Collapse
|
23
|
Nagao M, Takatori T, Matsuda Y, Nakajima M, Iwase H, Iwadate K. Definitive evidence for the acute sarin poisoning diagnosis in the Tokyo subway. Toxicol Appl Pharmacol 1997; 144:198-203. [PMID: 9169085 DOI: 10.1006/taap.1997.8110] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A new method was developed to detect sarin hydrolysis products from erythrocytes of four victims of sarin (isopropylmethylphosphonofluoridate) poisoning resulting from the terrorist attack on the Tokyo subway. Sarin-bound acetylcholinesterase (AChE) was solubilized from erythrocyte membranes of sarin victims, digested with trypsin, the sarin hydrolysis products bound to AChE were released by alkaline phosphatase digestion, and the digested sarin hydrolysis products were subjected to trimethylsilyl derivatization and detected by gas chromatography-mass spectrometry. Isopropylmethylphosphonic acid, which is a sarin hydrolysis product, was detected in all sarin poisoning, victims we examined and methylphosphonic acid, which is a sarin and soman hydrolysis product, was determined in all victims. Postmortem examinations revealed no macroscopic and microscopic findings specific to sarin poisoning and sarin and its hydrolysis products were almost undetectable in their blood. We think that the procedure described below will be useful for the forensic diagnosis of acute sarin poisoning.
Collapse
Affiliation(s)
- M Nagao
- Faculty of Medicine, Department of Forensic Medicine, University of Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
24
|
Deadwyler G, Sima PD, Fu Y, Kanofsky JR. Singlet oxygen-mediated inactivation of acetylcholinesterase: a comparison of purified enzyme in solution and enzyme bound to K562 leukemia cells. Photochem Photobiol 1997; 65:884-94. [PMID: 9155262 DOI: 10.1111/j.1751-1097.1997.tb01939.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have compared the singlet oxygen-mediated inactivation of acetylcholinesterase (ACE) in solution with the inactivation of ACE on the surface of K562 leukemia cells. In solution, the actions of the singlet-oxygen quenchers, methionine, azide, disodium [N,N'-ethylenebis (5-sulfosalicylideneimminato)]nickelate(II) (Ni-chelate 1) and disodium [(N,N'-2,3-propionic acid)bis(5-sulfosal-icylideneimminato)] nickelate(II) (Ni-chelate 2) could be explained quantitatively by assuming their only mechanism of action was to quench singlet oxygen. The singlet oxygen quenchers, azide, Ni-chelate 1 and Ni-chelate 2, caused smaller inhibitions in the rate of singlet oxygen-mediated inactivation of ACE on K562 cells than ACE in solution. The effects of these quenchers and of deuterium oxide were interpreted using a mathematical model of singlet-oxygen quenching and diffusion to estimate the lifetime of singlet oxygen near the cell surface. The azide quenching data and the deuterium-oxide data gave lifetimes of 0.9 +/- 0.2 microsecond and 0.45 +/- 0.15 microsecond, respectively. The increases in ACE inactivation lifetime caused by the nickel chelates were anomalously large. The unexpectedly large quenching due to the nickel chelates may have been due to a nonuniform distribution of the chelates in the cytoplasm with a large concentration of the chelate near the cell membrane.
Collapse
Affiliation(s)
- G Deadwyler
- Hines Veterans Affairs Hospital, IL 60141, USA
| | | | | | | |
Collapse
|
25
|
Armesto J, Hannappel E, Leopold K, Fischer W, Bublitz R, Langer L, Cumme GA, Horn A. Microheterogeneity of the hydrophobic and hydrophilic part of the glycosylphosphatidylinositol anchor of alkaline phosphatase from calf intestine. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:259-69. [PMID: 8665945 DOI: 10.1111/j.1432-1033.1996.0259q.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Digestion of calf intestine alkaline phosphatase with pronase and subsequent dephosphorylation of the released peptidyl-(Etn-P)2-glycosyl-PtdIns with HF generated 8 glycosyl-Ins species the largest of which (G1 and G2) have the following proposed structures: [sequence: see text] G3 and G5 are lower homologues of G1 and G2, respectively, being one alpha 1-2 linked mannopyranosyl residue shorter. G4 is analogous to G2 lacking the N-acetylgalactosaminyl residue and G6 is the next lower homologue of G4. Most of G4 and G6 occur substituted with a palmitoyl (G4, G6) or a myristoyl residue (G6) probably attached to the inositol moiety. Thus, the basic ManxGlc-Ins species are either substituted with an N-acetylgalactosaminyl residue or a fatty acid ester. The structures were deduced from compositional analysis, molecular-mass determination by matrix-assisted laser desorption MS, sequential hydrolysis with appropriate exoglycosidases and treatment with CrO3. Purification of the glycosylinositol species was achieved by a novel reverse-phase HPLC technique using fluorescent fluoren-9-yl-methoxy-carbonyl (Fmoc) derivatives. These stable derivatives were susceptible to hydrolysis with exoglycosidases which allowed sequential cleavages to be carried out and kinetics to be followed at the picomole level. We observed recently that native alkaline phosphatase separates on octyl-Sepharose into four distinct fractions of increasing hydrophobicity (F1-F4). Here we show that all four fractions contain G1-G6. The acylated species G4 and G6 were restricted to F2 and F4 which had been shown earlier to contain, on average, 2.5 and 3 fatty acid residues/subunit, respectively. In all four fractions the diradylglycerol moiety was predominantly diacylglycerol, alkylacylglycerol being less than 10% which is in contrast to most glycosyl-PtdIns--anchored proteins of mammalian origin.
Collapse
Affiliation(s)
- J Armesto
- Institut für Biochemie, Medizinische Fakultät, Universität Erlangen-Nürnberg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Haas R, Jackson BC, Reinhold B, Foster JD, Rosenberry TL. Glycoinositol phospholipid anchor and protein C-terminus of bovine erythrocyte acetylcholinesterase: analysis by mass spectrometry and by protein and DNA sequencing. Biochem J 1996; 314 ( Pt 3):817-25. [PMID: 8615775 PMCID: PMC1217130 DOI: 10.1042/bj3140817] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Purified bovine erythrocyte acetylcholinesterase (AChE) was radiomethylated on its amine groups and incubated with bacterial phosphatidylinositol-specific phospholipase C to remove the lipid portion of the AChE glycoinositol phospholipid (GPI) anchor, and a C-terminal tryptic fragment that contained the residual GPI glycan was isolated by HPLC. Analysis by electrospray-ionization mass spectrometry revealed a parent ion of m/z 3798. The fragmentation patterns produced by collision-induced dissociation mass spectrometry of the +4 and +5 states of the parent ion indicated a 23-amino acid peptide in amide linkage to ethanolamine-P04-Hex-Hex-Hex(PO4-ethanolamine)(HexNAc)-Hex N(Me)2-inositol phosphate. The glycan structure is completely consistent with that obtained previously for the GPI anchor of human erythrocyte AChE except for the addition of the HexNAc substituent. A nearly complete peptide sequence was deduced from the fragmentation patterns, although four assignments were based only on single fragments of very low abundance. To resolve this uncertainty, a segment of bovine genomic DNA corresponding to the C-terminal AChE sequence was amplified by PCR. DNA sequencing established the 23-amino acid peptide sequence to be FLPKLLSATASEAPCTCSGPAHG, in agreement with the MS data and consistent with results from Edman protein sequencing. Dimerization of AChE polypeptides is mediated by intersubunit disulphide bonding in this C-terminal segment, but the bovine AChE contained two cysteine residues in a ...CTC... motif, in contrast with human AChE which contains only a single cysteine in this segment. Although bovine AChE contained no free thiol groups reactive with iodo[14C]acetamide, partial reduction and alkylation with iodo[14C]acetamide revealed that conversion into monomers occurred with an overall incorporation of only one alkyl group per monomer. An identical level of alkylation was observed when dimeric human AChE was converted into monomers by partial reduction. The question of whether the bovine AChE contains one or two intersubunit disulphide linkages is considered.
Collapse
Affiliation(s)
- R Haas
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | | | | | | | | |
Collapse
|
27
|
Llanes C, Collman RG, Hrin R, Kolson DL. Acetylcholinesterase expression in NTera 2 human neuronal cells: a model for developmental expression in the nervous system. J Neurosci Res 1995; 42:791-802. [PMID: 8847741 DOI: 10.1002/jnr.490420608] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Acetylcholinesterase (AChE; EC 3.1.1.7) is expressed in the central nervous system in multiple molecular forms that may subserve multiple functions and may be selectively lost in neurodegenerative illnesses such as Alzheimer's disease. AChE expression has been studied in primary cultures of developing vertebrate nervous system, but investigation has been limited by the lack of a suitable human CNS surrogate cell model system for in vitro studies and the inability of primary brain cultures to provide large numbers of pure neurons. To develop an in vitro model for studies of neuronal AChE expression and function, we utilized a neuronally committed human teratocarcinoma cell line, NTera 2, that can be induced to differentiate to a post-mitotic CNS neuronal phenotype. We found that NTera 2 cells express multiple molecular forms of AChE that are similar to CNS-derived AChE isoforms in velocity sedimentation profile, anion exchange elution profile, and sensitivity to inhibitors. At least two forms of AChE are expressed (G1 and G4), similar to human and rodent brain, and induction of NTera 2 cell differentiation results in an increased G4/G1 ratio, which is characteristic of mature neurons. As in primary CNS neurons, AChE is present in NTera 2 cells in both the cytosolic fraction and in the outer membrane, and is also released in a soluble form. These observations indicate that NTera 2 cells provide a useful human model system for studies of expression of cell-associated and soluble cell-free AChE in developing and mature human neurons and for elucidating the potential role(s) of acetylcholinesterase metabolism in both normal development and neurodegenerative disease states.
Collapse
Affiliation(s)
- C Llanes
- Department of Neurology, University of Pennsylvania Medical Center, Philadelphia, USA
| | | | | | | |
Collapse
|
28
|
Affiliation(s)
- V L Stevens
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA 30335, USA
| |
Collapse
|
29
|
Eastman J, Wilson EJ, Cerveñansky C, Rosenberry TL. Fasciculin 2 binds to the peripheral site on acetylcholinesterase and inhibits substrate hydrolysis by slowing a step involving proton transfer during enzyme acylation. J Biol Chem 1995; 270:19694-701. [PMID: 7649979 DOI: 10.1074/jbc.270.34.19694] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The acetylcholinesterase active site consists of a gorge 20 A deep that is lined with aromatic residues. A serine residue near the base of the gorge defines an acylation site where an acyl enzyme intermediate is formed during the hydrolysis of ester substrates. Residues near the entrance to the gorge comprise a peripheral site where inhibitors like propidium and fasciculin 2, a snake neurotoxin, bind and interfere with catalysis. We report here the association and dissociation rate constants for fasciculin 2 interaction with the human enzyme in the presence of ligands that bind to either the peripheral site or the acylation site. These kinetic data confirmed that propidium is strictly competitive with fasciculin 2 for binding to the peripheral site. In contrast, edrophonium, N-methylacridinium, and butyrylthiocholine bound to the acylation site and formed ternary complexes with the fasciculin 2-bound enzyme in which their affinities were reduced by about an order of magnitude from their affinities in the free enzyme. Steady state analysis of the inhibition of substrate hydrolysis by fasciculin 2 revealed that the ternary complexes had residual activity. For acetylthiocholine and phenyl acetate, saturating amounts of the toxin reduced the first-order rate constant kcat to 0.5-2% and the second-order rate constant kcat/Kapp to 0.2-2% of their values with the uninhibited enzyme. To address whether fasciculin 2 inhibition primarily involved steric blockade of the active site or conformational interaction with the acylation site, deuterium oxide isotope effects on these kinetic parameters were measured. The isotope effect on kcat/Kapp increased for both substrates when fasciculin 2 was bound to the enzyme, indicating that fasciculin 2 acts predominantly by altering the conformation of the active site in the ternary complex so that steps involving proton transfer during enzyme acylation are slowed.
Collapse
Affiliation(s)
- J Eastman
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44120-4965, USA
| | | | | | | |
Collapse
|
30
|
Sánchez-Chávez G, Vidal CJ, Salceda R. Acetyl- and butyrylcholinesterase activities in the rat retina and retinal pigment epithelium. J Neurosci Res 1995; 41:655-62. [PMID: 7563246 DOI: 10.1002/jnr.490410512] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities in the neural retina and retinal pigment epithelium (RPE) of adult rats were determined. The tissues were extracted with a saline buffer to release the soluble enzymes (S1) and the pellet re-extracted with Triton X-100 to detach the membrane-bound enzymes (S2). Less than 5% of the cholinesterase activity measured in retina and almost 30% of that assayed in RPE was due to BChE. About 20% and 10% of the AChE in retina and RPE was brought into solution with a saline buffer and the rest with a detergent-containing buffer. Main AChE molecular forms of 10.5S (hydrophilic G4H), 9.5S (amphiphilic G4A) and 3.0S (amphiphilic G1A) were identified in retina by subjecting the supernatant S1 to sedimentation analysis in sucrose gradients made with Brij 96. Amphiphilic G4 and G1 AChE were found in S2. Analysis of the soluble fractions obtained from RPE in the gradients made with Brij 96 revealed 16.0S (asymmetric A12), 10.5-10.0S (globular G4H + G4A), 4.5S (G2A), and 3.0S (G1A) AChE forms in S1, whereas G4A, G2A, and G1A enzyme molecules predominated in S2. Our results show that amphiphilic tetramers and monomers of AChE are abundant in neural retina, and enzyme tetramers, dimers, and monomers in RPE. The AChE in the neural retina might be involved in cholinergic actions. The enzyme function in the retinal pigment epithelium remains to be established.
Collapse
|
31
|
Venisse A, Rivière M, Vercauteren J, Puzo G. Structural analysis of the mannan region of lipoarabinomannan from Mycobacterium bovis BCG. Heterogeneity in phosphorylation state. J Biol Chem 1995; 270:15012-21. [PMID: 7797482 DOI: 10.1074/jbc.270.25.15012] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Lipoarabinomannan (LAM) is a major antigen of mycobacterial cell walls, involved in host-Mycobacterium interactions. In a previous work, LAM from the vaccine strain, Mycobacterium bovis BCG, was found to exhibit mannooligosaccharides at its arabinan nonreducing ends (ManLAM). The present report concerns the mannan core structure of this ManLAM. After partial hydrolysis of ManLAM, two populations of mannans (Ma1 and Ma2) were obtained by gel filtration chromatography. Their structural features were defined by means of two-dimensional homo- and heteronuclear (1H-13C) NMR sequences and methylation analysis. They were both found to be composed of an alpha-(1-->6)-linked mannan backbone with alpha-(1-->2)-Manp-linked side chains. They are highly branched, and Ma2 presents a higher frequency of branching than Ma1. Moreover, chemical analysis indicates that only Ma1 is phosphorylated. By a two-dimensional heteronuclear 1H-31P total correlation experiment, the phosphate was found to be involved in a phosphodiester bond between inositol C-1 and glycerol C-3. Then, the molecular mass of mannan was established by mass spectrometry, which revealed a molecular mass of 3517 Da for the major molecular species of Ma1. Likewise, analysis of unfractionated mannans showed the occurrence of other, quantitatively minor molecular species, endowed with two phosphates. This study clearly indicates that the mannan region of M. bovis BCG ManLAM exists as a heterogeneous population of molecules whose structures differ in their degree of glycosylation, level of branching, and phosphorylation state. The hypothesis that the relative abundance of these different molecules modulates the biological functions of LAM is discussed.
Collapse
Affiliation(s)
- A Venisse
- Laboratoire de Pharmacologie et de Toxicologie Fondamentales du CNRS, Département III, Toulouse, France
| | | | | | | |
Collapse
|
32
|
Stevens VL, Zhang H. Coenzyme A dependence of glycosylphosphatidylinositol biosynthesis in a mammalian cell-free system. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)31707-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
33
|
|
34
|
McCoy J, Mann B, Vedvick T, Pak Y, Heimark D, Petri W. Structural analysis of the light subunit of the Entamoeba histolytica galactose-specific adherence lectin. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80514-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
35
|
Bublitz R, Armesto J, Hoffmann-Blume E, Schulze M, Rhode H, Horn A, Aulwurm S, Hannappel E, Fischer W. Heterogeneity of glycosylphosphatidylinositol-anchored alkaline phosphatase of calf intestine. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 217:199-207. [PMID: 8223555 DOI: 10.1111/j.1432-1033.1993.tb18234.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A method is described for large-scale purification of glycosylphosphatidylinositol-anchored alkaline phosphatase from intestinal mucosa and chyme to homogeneity. Both enzyme preparations contain approximately 2 mol fatty acid/mol subunit and exhibit a very similar fatty acid composition with octadecanoate and hexadecanoate as prevalent components. No significant differences between native glycosylPtdIns-anchored and hydrophilic alkaline phosphatases from both sources were found regarding Km, Vmax, the type of inhibition and inhibition constants of the amino acids L-leucine, L-phenylalanine, and L-tryptophan. The purified enzymes of both sources yield diacylglycerol and phosphatidic acid, after treatment with phosphatidylinositol-specific phospholipase C (PtdIns-PLC) and glycosylphosphatidylinositol phospholipase D (PLD), respectively. Enzyme preparations of both sources appear as heterogeneous mixtures of five fractions separable by octyl-Sepharose chromatography. Fraction I corresponds to the anchorless enzyme, fractions II-V differ in their susceptibility to phospholipases. Fractions II and IV are completely split by PtdIns-PLC or PLD action, almost 50% of fraction III is split by PtdIns-PLC, while fraction V is resistant. The susceptibility of these two fractions toward the action of PLD is considerably higher. Fatty acid analysis yields molar ratios of fatty acids/alkaline phosphatase subunit of 1.78, 2.58, 2.24, and 3.37 for fractions II, III, IV, and V, respectively. Aggregates of glycosylPtdIns-anchored alkaline phosphatase of all fractions are seen in native PAGE in the presence of Triton X-100. By gel chromatography in the presence of Brij 35, fractions II-V form stable multiple aggregates of dimers and may bind different amounts of the detergent. These data, together with fatty acid analysis, can be interpreted by the following model. Fractions II and IV are tetramers and octamers with two molecules fatty acid/subunit. Fraction III is a tetramer, bearing one additional fatty acid molecule, localized on the dimer. Fraction V is an octamer, containing glycosylPtdIns-anchor molecules with three molecules fatty acids/anchor molecule. The additional fatty acid residue is possibly located on inositol and responsible for the reduced susceptibility to PtdIns-PLC. The similarity of all measured parameters of both enzymes suggests that the glycosylPtdIns-anchored alkaline phosphatase of the mucosa is released into the chyme without changing the anchor molecule constituents.
Collapse
Affiliation(s)
- R Bublitz
- Institute of Biochemistry, Medical Faculty, Friedrich Schiller University of Jena, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Sáez-Valero J, Tornel PL, Muñoz-Delgado E, Vidal CJ. Amphiphilic and hydrophilic forms of acetyl- and butyrylcholinesterase in human brain. J Neurosci Res 1993; 35:678-89. [PMID: 8411269 DOI: 10.1002/jnr.490350610] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Human brain acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were sequentially extracted, first with a Tris-saline buffer (S1) and then with 1% (w/v) Triton X-100 (S2). About 20 and 30% of the AChE and BuChE activities were recovered in S1 and most of the remaining enzymes in S2. Main molecular forms of about 10.5 S and 12.0 S, G4 forms of AChE and BuChE, and smaller amounts of 4.5 S and 5.5 S forms, G1 species of AChE and BuChE, were measured in S1. Application of Triton X-114 phase partitioning and affinity chromatography on phenyl-agarose to S1 revealed that 25% of the AChE and none of the BuChE molecules displayed amphiphilic properties. Analysis of the enzyme activity retained by the phenyl-agarose showed that G1 AChE constituted the bulk of the amphiphilic molecules released without detergent. Main G4 forms of AChE and BuChE were found in the S2 extract. Eighty and 45% of the AChE and BuChE activities in S2 were measured in the detergent-rich phase by Triton X-114 phase partitioning. Thus, most of the AChE and about half of the BuChE molecules in S2 displayed amphiphilic properties. The main peak of BuChE, a 12.0 S form in gradients made with Triton X-100, splits into two peaks of 9.5 S and 12.5 S in Brij 96-containing gradients. This suggests that hydrophilic G4 BuChE forms are predominant in S1 and that hydrophilic and amphiphilic isoforms coexist in S2.
Collapse
Affiliation(s)
- J Sáez-Valero
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Spain
| | | | | | | |
Collapse
|
37
|
Houenou LJ, Sahuqué MV, Villageois AP. Calcium influxes and calmodulin modulate the expression and physicochemical properties of acetylcholinesterase molecular forms during development in vivo. Cell Mol Neurobiol 1993; 13:217-32. [PMID: 8242686 DOI: 10.1007/bf00733751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
1. Acetylcholinesterase (AcChoE; EC 3.1.1.7) exists in several molecular forms that may be anchored to cell membranes or associated with extracellular matrix. AcChoE bound to lipidic membranes is detergent extractable (DE AcChoE), whereas the enzyme associated with extracellular matrix is high salt soluble (HSS AcChoE). The latter variant is accumulated in synaptic regions by an unknown mechanism. 2. We have suggested previously that depolarization-induced Ca2+ influx is a major factor that modulates AcChoE synthesis in vivo, as well as the conversion of some DE AcChoE to HSS variant. In the present study, we have examined (i) the effects of depolarization-induced skeletal muscle inactivity and ionophore-induced Ca2+ influxes on the expression of AcChoE molecular forms and (ii) the hypothesis that Ca(2+)-dependent calmodulin may be involved in the conversion of at least some forms of DE AcChoE to HSS variant in vivo. 3. Chick embryos were treated in ovo during the early period of nerve-muscle interactions with d-tubocurarine (dTC; a competitive neuromuscular blocking agent) or with decamethonium (dMET; a depolarizing agent). Both dTC and dMET equally and significantly reduced embryonic neuromuscular activity (motility). However, dTC significantly decreased AcChoE overall activity, whereas dMET had virtually no effect on AcChoE expression, compared to controls. 4. Treatment of embryos with the Ca2+ ionophore A23187 significantly increased the total AcChoE activity as well as the DE/HSS ratio of each AcChoE molecular form. However, treatment with N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide (also termed W-7), a calmodulin antagonist, did not alter the total AcChoE activity, but significantly increased the DE/HSS ratio of AcChoE forms. 5. These results support the idea that (i) depolarization and/or Ca2+ influxes, but not muscle contraction, may regulate AcChoE expression in skeletal muscle and (ii) Ca(2+)-dependent calmodulin activation may be involved in the conversion of some DE AcChoE to their HSS variant in vivo.
Collapse
Affiliation(s)
- L J Houenou
- Department of Neurobiology and Anatomy, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157
| | | | | |
Collapse
|
38
|
Motoyama N, Okada N, Yamashina M, Okada H. Paroxysmal nocturnal hemoglobinuria due to hereditary nucleotide deletion in the HRF20 (CD59) gene. Eur J Immunol 1992; 22:2669-73. [PMID: 1382994 DOI: 10.1002/eji.1830221029] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
HRF20 (CD59) is a membrane glycoprotein which protects cells from the membrane attack reaction of homologous complement. A patient who is completely deficient in HRF20 expression and is suffering from paroxysmal nocturnal hemoglobinuria (PNH) was studied. His parents are cousins and both have decreased HRF20 expression, suggesting that the deficiency is genetic. We established a cultured cell line (NCU1) which is HRF20 deficient from the patient's lymphocytes by Epstein-Barr-virus (EBV) infection. Northern blot analysis revealed HRF20 mRNA signals, indicating that HRF20 mRNA were transcribed. HRF20 cDNA was amplified by the polymerase chain reaction (PCR) method. Sequencing of the cDNA from the NCU1 showed two single-base deletions at amino acid 16 and 96 from the N terminus of the mature protein. Deletion in the genomic DNA of peripheral blood lymphocytes was confirmed by the DNA sequence of an HRF20 open reading frame containing amino acid 16. Furthermore, the patient's parents and sister possessed both intact and deleted genomic HRF20 DNA while his brother's DNA was intact. These findings demonstrate that the HRF20 deficiency was genomic in origin, and that complete deletion was brought about by a homozygous abnormality in the HRF20 gene. The base deletion caused a codon frame shift resulting in failure to produce intact HRF20 protein in the patient.
Collapse
Affiliation(s)
- N Motoyama
- Department of Molecular Biology, Nagoya City University School of Medicine, Japan
| | | | | | | |
Collapse
|
39
|
Getman DK, Eubanks JH, Camp S, Evans GA, Taylor P. The human gene encoding acetylcholinesterase is located on the long arm of chromosome 7. Am J Hum Genet 1992; 51:170-7. [PMID: 1609795 PMCID: PMC1682883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Acetylcholinesterase (AChE) is a secreted enzyme essential for regulating cholinergic neurotransmission at neuronal and neuromuscular synapses. In view of the altered expression of AChE in some central neurological and neuromuscular disorders with a probable genetic basis, we have identified the chromosomal location of the gene encoding AChE. Chromosomal in situ suppression hybridization analysis revealed a single gene to be at 7q22, a result which was confirmed by PCR analysis of genomic DNA from a human/hamster somatic cell hybrid containing a single human chromosome 7. The AChE gene thus maps to the same region in which frequent nonrandom chromosome 7 deletions occur in leukemias of myeloid cell precursors known to express the enzyme during normal differentiation.
Collapse
Affiliation(s)
- D K Getman
- Department of Pharmacology, University of California-San Diego, La Jolla 92093-0636
| | | | | | | | | |
Collapse
|
40
|
Hughes TR, Piddlesden SJ, Williams JD, Harrison RA, Morgan BP. Isolation and characterization of a membrane protein from rat erythrocytes which inhibits lysis by the membrane attack complex of rat complement. Biochem J 1992; 284 ( Pt 1):169-76. [PMID: 1376109 PMCID: PMC1132712 DOI: 10.1042/bj2840169] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The membrane attack complex (MAC) of complement in humans is regulated by several membrane-bound proteins; however, no such proteins have so far been described in other species. Here we report the isolation and characterization of a rat erythrocyte membrane glycoprotein of molecular mass 21 kDa which inserts into cell membranes and is a potent inhibitor of the rat MAC. This protein, here called rat inhibitory protein (RIP), was first partially purified by column chromatography from a butanol extract of rat erythrocyte membranes. Monoclonal antibodies (Mabs) were raised against RIP and used for its affinity purification. Affinity-purified RIP was shown to inhibit in a dose-dependent manner the cobra venom factor (CVF)-mediated 'reactive' lysis of guinea pig erythrocytes by rat complement. Conversely, the anti-RIP MAbs 6D1 and TH9 were shown to markedly enhance the CVF-mediated lysis of rat erythrocytes by rat complement. RIP acted late in the assembly of the MAC (at or after the C5b-8 stage) and was releasable from the membranes of rat erythrocytes by phosphatidylinositol-specific phospholipase C. These features, together with its size, deglycosylation pattern and N-terminal amino acid sequence, lead us to conclude that RIP is the rat homologue of the human MAC-inhibitory protein CD59 antigen.
Collapse
Affiliation(s)
- T R Hughes
- Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff, U.K
| | | | | | | | | |
Collapse
|
41
|
Verma R, Gullapalli S, Antony A. Evidence that the hydrophobicity of isolated, in situ, and de novo-synthesized native human placental folate receptors is a function of glycosyl-phosphatidylinositol anchoring to membranes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50637-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
42
|
Affiliation(s)
- M H Holguin
- Hematology/Oncology Section (111C), Veterans Administration Medical Center, Salt Lake City, UT 84148
| | | |
Collapse
|
43
|
Affiliation(s)
- D M Lublin
- Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110
| |
Collapse
|
44
|
Gene structure of mammalian acetylcholinesterase. Alternative exons dictate tissue-specific expression. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54466-5] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
45
|
Low MG, Huang KS. Factors affecting the ability of glycosylphosphatidylinositol-specific phospholipase D to degrade the membrane anchors of cell surface proteins. Biochem J 1991; 279 ( Pt 2):483-93. [PMID: 1835378 PMCID: PMC1151630 DOI: 10.1042/bj2790483] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mammalian serum and plasma contain high levels of glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD). Previous studies with crude serum or partially purified GPI-PLD have shown that this enzyme is capable of degrading the GPI anchor of several purified detergent-solubilized cell surface proteins yet is unable to act on GPI-anchored proteins located in intact cells. Treatment of intact ROS17/2.8, WISH or HeLa cells (or membrane fractions prepared from them) with GPI-PLD purified from bovine serum by immunoaffinity chromatography gave no detectable release of alkaline phosphatase into the medium. However, when membranes were treated with GPI-PLD in the presence of 0.1% Nonidet P-40 substantial GPI anchor degradation (as measured by Triton X-114 phase separation) was observed. The mechanism of this stimulatory effect of detergent was further investigated using [3H]myristate-labelled variant surface glycoprotein and human placental alkaline phosphatase reconstituted into phospholipid vesicles. As with the cell membranes the reconstituted substrates exhibited marked resistance to the action of purified GPI-PLD which could be overcome by the inclusion of Nonidet P-40. Similar results were obtained when crude bovine serum was used as the source of GPI-PLD. These data indicate that the resistance of cell membranes to the action of GPI-PLD is not entirely due to the action of serum or membrane-associated inhibitory factors. A more likely explanation is that, in common with many other eukaryotic phospholipases, the action of GPI-PLD is restricted by the physical state of the phospholipid bilayer in which the substrates are embedded. These data may account for the ability of endothelial and blood cells to retain GPI-anchored proteins on their surfaces in spite of the high levels of GPI-PLD present in plasma.
Collapse
Affiliation(s)
- M G Low
- Rover Physiology Research Laboratories, Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons of Columbia University, NY 10032
| | | |
Collapse
|
46
|
Stieger S, Diem S, Jakob A, Brodbeck U. Enzymatic properties of phosphatidylinositol-glycan-specific phospholipase C from rat liver and phosphatidylinositol-glycan-specific phospholipase D from rat serum. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 197:67-73. [PMID: 1849823 DOI: 10.1111/j.1432-1033.1991.tb15883.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using phosphatidylinositol-glycan (PtdIns-glycan) anchored acetylcholinesterase from bovine erythrocytes as substrate, we found PtdIns-glycan-anchor-degrading activity in rat liver and serum [corrected]. The hepatic enzyme was only soluble in detergents, whereas the serum enzyme occurs as soluble, slightly amphiphilic protein. Using 3-trifluoromethyl-3-(m- [125I]iodophenyl)diazirine-labelled acetylcholinesterase as substrate, we showed that the hepatic anchor-degrading enzyme had a cleavage specificity of a phospholipase C, whereas the serum enzyme was a phospholipase D. Both enzyme exhibited maximal activity in slightly acidic conditions and at low ionic strength. They had a high affinity for the PtdIns-glycan anchor of the substrate (Km = 0.1 microM and 0.16 microM, respectively). Both hepatic PtdIns-glycan-specific phospholipase C and serum PtdIns-glycan-specific phospholipase D gave a large increase in activity between 0.1-10 microM Ca2+, indicating that PtdIns-glycan-specific phospholipases are only marginally active at physiological intracellular Ca2+ concentrations. The enzymes were inhibited by heavy metal chelating agents such as 1,10-phenanthroline and 2,2'-bipyridyl but not by the corresponding Fe2+ complexes or non-chelating analogues, indicating that they both require a heavy metal ion for the expression of catalytic activity in addition to Ca2+. Another interesting property of PtdIns-glycan-specific phospholipases is their inactivation by bicarbonate and cyanate. The inactivation was time- and pH-dependent and could be reversed by dialysis. These observations are in agreement with a covalent modification of the enzymes by carbamoylation.
Collapse
Affiliation(s)
- S Stieger
- Institut für Biochemie und Molekularbiologie, Universität Bern, Switzerland
| | | | | | | |
Collapse
|
47
|
Roberts WL, Doctor BP, Foster JD, Rosenberry TL. Bovine brain acetylcholinesterase primary sequence involved in intersubunit disulfide linkages. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(20)89471-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
48
|
|
49
|
Toutant JP, Krall JA, Richards MK, Rosenberry TL. Rapid analysis of glycolipid anchors in amphiphilic dimers of acetylcholinesterases. Cell Mol Neurobiol 1991; 11:219-30. [PMID: 1849455 DOI: 10.1007/bf00712811] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
1. We describe two simple procedures for the rapid identification of certain structural features of glycolipid anchors in acetylcholinesterases (AChEs). 2. Treatment with alkaline hydroxylamine (that cleaves ester-linked acyl chains but not ether-linked alkyl chains) converts molecules possessing a diacylglycerol, but not those with an alkylacylglycerol, into hydrophilic derivatives. AChEs in human and bovine erythrocytes possess an alkylacylglycerol (Roberts et al., J. Biol. Chem. 263:18766-18775, 1988; Biochem. Biophys. Res. Commun. 150:271-277, 1988) and are not converted to hydrophilic dimers by alkaline hydroxylamine. Amphiphilic dimers of AChE from Drosophila, from mouse erythrocytes, and from the human erythroleukaemia cell line K562 also resist the treatment with hydroxylamine and likely possess a terminal alkylacylglycerol. This indicates that the cellular pool of free glycolipids used as precursors of protein anchors is distinct from the pool of membrane phosphatidylinositols (which contain diacylglycerols). 3. Pretreatment with alkaline hydroxylamine is required to render the amphiphilic AChE from human erythrocytes susceptible to digestion by Bacillus thuringiensis phosphatidylinositol-specific phospholipase C (PI-PLC) (Toutant et al., Eur. J. Biochem. 180:503-508, 1989). We show here that this is also the case for the AChE from mouse erythrocytes, which therefore likely possesses an additional acyl chain in the anchor that prevents the action of PI-PLC. 4. In two sublines of K562 cells (48 and 243), we observed that AChE either was directly susceptible to PI-PLC (243) or required a prior deacylation by alkaline hydroxylamine (48). This suggests that glycolipid anchors in AChE of K562-48 cells, but not those in AChE of K562-243 cells, contain the additional acylation demonstrated in AChE from human erythrocytes. These observations illustrate the cell specificity (and the lack of species-specificity) of the structure of glycolipid anchors.
Collapse
Affiliation(s)
- J P Toutant
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | | | | | | |
Collapse
|
50
|
Heider H, Litynski P, Stieger S, Brodbeck U. Comparative studies on the primary structure of acetylcholinesterases from bovine caudate nucleus and bovine erythrocytes. Cell Mol Neurobiol 1991; 11:105-18. [PMID: 2013055 DOI: 10.1007/bf00712803] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
1. Comparison of partial amino acid sequences of G2-acetylcholinesterase (AChE) from bovine erythrocytes and G4-AChE from bovine caudate nucleus revealed no differences in primary structure between the two enzymes. The first 33 residues of the N-terminal sequences were identical. 2. In addition, the amino acid sequences of four peptides generated by tryptic and cyanogen bromide cleavage were identical for bovine erythrocyte and brain AChE, suggesting one identical major coding exon for the adult bovine AChE forms. Comparison of these sequences with that of fetal bovine serum AChE (Doctor et al., 1988), showed differences in residues 16, 181, 212, and 216. 3. Deglycosylation studies of the two adult enzyme forms revealed that the core protein of erythrocyte AChE has an approximately 4 kDa lower molecular mass than brain AChE. This most probably reflects differences in the C-terminal sequences of the two enzymes.
Collapse
Affiliation(s)
- H Heider
- Institut für Biochemie und Molekularbiologie, Universität Bern, Switzerland
| | | | | | | |
Collapse
|