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Smith JB, Alloway KD, Hof PR, Orman R, Reser DH, Watakabe A, Watson GDR. The relationship between the claustrum and endopiriform nucleus: A perspective towards consensus on cross-species homology. J Comp Neurol 2019; 527:476-499. [PMID: 30225888 PMCID: PMC6421118 DOI: 10.1002/cne.24537] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 01/08/2023]
Abstract
With the emergence of interest in studying the claustrum, a recent special issue of the Journal of Comparative Neurology dedicated to the claustrum (Volume 525, Issue 6, pp. 1313-1513) brought to light questions concerning the relationship between the claustrum (CLA) and a region immediately ventral known as the endopiriform nucleus (En). These structures have been identified as separate entities in rodents but appear as a single continuous structure in primates. During the recent Society for Claustrum Research meeting, a panel of experts presented data pertaining to the relationship of these regions and held a discussion on whether the CLA and En should be considered (a) separate unrelated structures, (b) separate nuclei within the same formation, or (c) subregions of a continuous structure. This review article summarizes that discussion, presenting comparisons of the cytoarchitecture, neurochemical profiles, genetic markers, and anatomical connectivity of the CLA and En across several mammalian species. In rodents, we conclude that the CLA and the dorsal endopiriform nucleus (DEn) are subregions of a larger complex, which likely performs analogous computations and exert similar effects on their respective cortical targets (e.g., sensorimotor versus limbic). Moving forward, we recommend that the field retain the nomenclature currently employed for this region but should continue to examine the delineation of these structures across different species. Using thorough descriptions of a variety of anatomical features, this review offers a clear definition of the CLA and En in rodents, which provides a framework for identifying homologous structures in primates.
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Affiliation(s)
- Jared B. Smith
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Kevin D. Alloway
- Neural and Behavioral Sciences, Center for Neural Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Patrick R. Hof
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Rena Orman
- Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY, 11203 USA
| | - David H. Reser
- Graduate Entry Medicine Program, Monash Rural Health Churchill, Monash University, Churchill, Victoria 3842, Australia
- Department of Physiology, Monash University, Clayton 3800, Victoria, Australia
| | | | - Glenn D. R. Watson
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
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2
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Myelin Basic Protein Citrullination in Multiple Sclerosis: A Potential Therapeutic Target for the Pathology. Neurochem Res 2016; 41:1845-56. [PMID: 27097548 DOI: 10.1007/s11064-016-1920-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/02/2016] [Accepted: 04/13/2016] [Indexed: 10/21/2022]
Abstract
Multiple sclerosis (MS) is a multifactorial demyelinating disease characterized by neurodegenerative events and autoimmune response against myelin component. Citrullination or deimination, a post-translational modification of protein-bound arginine into citrulline, catalyzed by Ca(2+) dependent peptidylarginine deiminase enzyme (PAD), plays an essential role in physiological processes include gene expression regulation, apoptosis and the plasticity of the central nervous system, while aberrant citrullination can generate new epitopes, thus involving in the initiation and/or progression of autoimmune disorder like MS. Myelin basic protein (MBP) is the major myelin protein and is generally considered to maintain the stability of the myelin sheath. This review describes the MBP citrullination and its consequence, as well as offering further support for the "inside-out" hypothesis that MS is primarily a neurodegenerative disease with secondary inflammatory demyelination. In addition, it discusses the role of MBP citrullination in the immune inflammation and explores the potential of inhibition of PAD enzymes as a therapeutic strategy for the disease.
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3
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Watson GDR, Smith JB, Alloway KD. Interhemispheric connections between the infralimbic and entorhinal cortices: The endopiriform nucleus has limbic connections that parallel the sensory and motor connections of the claustrum. J Comp Neurol 2016; 525:1363-1380. [PMID: 26860547 DOI: 10.1002/cne.23981] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 12/17/2022]
Abstract
We have previously shown that the claustrum is part of an interhemispheric circuit that interconnects somesthetic-motor and visual-motor cortical regions. The role of the claustrum in processing limbic information, however, is poorly understood. Some evidence suggests that the dorsal endopiriform nucleus (DEn), which lies immediately ventral to the claustrum, has connections with limbic cortical areas and should be considered part of a claustrum-DEn complex. To determine whether DEn has similar patterns of cortical connections as the claustrum, we used anterograde and retrograde tracing techniques to elucidate the connectivity of DEn. Following injections of retrograde tracers into DEn, labeled neurons appeared bilaterally in the infralimbic (IL) cortex and ipsilaterally in the entorhinal and piriform cortices. Anterograde tracer injections in DEn revealed labeled terminals in the same cortical regions, but only in the ipsilateral hemisphere. These tracer injections also revealed extensive longitudinal projections throughout the rostrocaudal extent of the nucleus. Dual retrograde tracer injections into IL and lateral entorhinal cortex (LEnt) revealed intermingling of labeled neurons in ipsilateral DEn, including many double-labeled neurons. In other experiments, anterograde and retrograde tracers were separately injected into IL of each hemisphere of the same animal. This revealed an interhemispheric circuit in which IL projects bilaterally to DEn, with the densest terminal labeling appearing in the contralateral hemisphere around retrogradely labeled neurons that project to IL in that hemisphere. By showing that DEn and claustrum have parallel sets of connections, these results suggest that DEn and claustrum perform similar functions in processing limbic and sensorimotor information, respectively. J. Comp. Neurol. 525:1363-1380, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Glenn D R Watson
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033.,Center for Neural Engineering, Pennsylvania State University, University Park, PA 16802
| | - Jared B Smith
- Center for Neural Engineering, Pennsylvania State University, University Park, PA 16802.,Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802
| | - Kevin D Alloway
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033.,Center for Neural Engineering, Pennsylvania State University, University Park, PA 16802
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4
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Ishigami A, Masutomi H, Handa S, Nakamura M, Nakaya S, Uchida Y, Saito Y, Murayama S, Jang B, Jeon YC, Choi EK, Kim YS, Kasahara Y, Maruyama N, Toda T. Mass spectrometric identification of citrullination sites and immunohistochemical detection of citrullinated glial fibrillary acidic protein in Alzheimer's disease brains. J Neurosci Res 2015; 93:1664-74. [DOI: 10.1002/jnr.23620] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/20/2015] [Accepted: 06/22/2015] [Indexed: 01/09/2023]
Affiliation(s)
- Akihito Ishigami
- Molecular Regulation of Aging; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Hirofumi Masutomi
- Molecular Regulation of Aging; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Setsuko Handa
- Molecular Regulation of Aging; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Megumi Nakamura
- Molecular Regulation of Aging; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Shuuichi Nakaya
- Global Applications Development Center; Shimadzu Corp.; Kyoto Japan
| | - Yoshiaki Uchida
- Research & Development Division; Fujirebio Inc.; Tokyo Japan
| | - Yuko Saito
- Department of Neuropathology; Tokyo Metropolitan Institute of Gerontology; Itabashi-ku, Tokyo Japan
| | - Shigeo Murayama
- Department of Neuropathology; Tokyo Metropolitan Institute of Gerontology; Itabashi-ku, Tokyo Japan
| | - Byungki Jang
- Ilsong Institute of Life Science; Hallym University; Anyang Gyeonggi-do Korea
| | - Yong-Chul Jeon
- Ilsong Institute of Life Science; Hallym University; Anyang Gyeonggi-do Korea
| | - Eun-Kyoung Choi
- Ilsong Institute of Life Science; Hallym University; Anyang Gyeonggi-do Korea
| | - Yong-Sun Kim
- Ilsong Institute of Life Science; Hallym University; Anyang Gyeonggi-do Korea
| | - Yasushi Kasahara
- Molecular Regulation of Aging; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
- Research & Development Division; Fujirebio Inc.; Tokyo Japan
| | - Naoki Maruyama
- Molecular Regulation of Aging; Tokyo Metropolitan Institute of Gerontology; Tokyo Japan
| | - Tosifusa Toda
- Advanced Medical Research Center; Yokohama City University; Yokohama Japan
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5
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Sabulski MJ, Wang Y, Pires MM. PAD2 Activity Monitored via a Fluorescent Substrate Analog. Chem Biol Drug Des 2015; 86:599-605. [PMID: 25643806 DOI: 10.1111/cbdd.12526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/02/2014] [Accepted: 01/08/2015] [Indexed: 11/29/2022]
Abstract
The post-transitional modification of peptidyl arginine to citrulline by PAD2 can affect the inherent biophysical properties of the citrullinated protein. Furthermore, dysregulation of PAD2 activity has been implicated in a number of human diseases. Inhibition of these enzymes by small molecules can serve as essential probes in establishing a link to pathogenesis. Herein, we describe a profluorescent substrate analog that reports on the activity and the inhibition of PAD2 in a robust assay. Most noteworthy, we expect future drug discovery efforts based on PAD2 inhibition can be pursued via this assay.
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Affiliation(s)
- Mary J Sabulski
- Chemistry Department, Lehigh University, Bethlehem, PA, 18015, USA
| | - Yanming Wang
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Marcos M Pires
- Chemistry Department, Lehigh University, Bethlehem, PA, 18015, USA
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Localisation of citrullinated proteins in normal appearing white matter and lesions in the central nervous system in multiple sclerosis. J Neuroimmunol 2014; 273:85-95. [DOI: 10.1016/j.jneuroim.2014.05.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 04/29/2014] [Accepted: 05/15/2014] [Indexed: 01/07/2023]
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7
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Dual immunofluorescence study of citrullinated proteins in Alzheimer diseased frontal cortex. Neurosci Lett 2013; 545:107-11. [PMID: 23648390 DOI: 10.1016/j.neulet.2013.04.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/05/2013] [Indexed: 11/23/2022]
Abstract
Deimination is a post-translational modification of proteins in which selected arginine amino acids are enzymatically converted to citrullines. Using dual-color immunofluorescence, the present study is the first to examine the frontal cortex of patients with Alzheimer's disease (AD) versus age-matched controls with an established monoclonal antibody (F95) against peptidyl-citrulline moieties. In AD specimens, a number of new findings were discovered, including evidence for deiminated proteins in extracellular plaques, the walls of large blood vessels, the nuclei of selective neurons immunoreactive for phosphorylated tau and numerous reactive astrocytes concentrated around extracellular plaques, ventricular surfaces and at the interface between the gray and white matter of the cortex. Although the identities of these citrullinated proteins remain largely unknown, the present study adds to the growing number of locations in which deiminated proteins may be found in the brains of patients with AD.
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8
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Dual immunofluorescence study of citrullinated proteins in Parkinson diseased substantia nigra. Neurosci Lett 2011; 495:26-9. [DOI: 10.1016/j.neulet.2011.03.028] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 02/15/2011] [Accepted: 03/08/2011] [Indexed: 11/21/2022]
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9
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Ishigami A, Maruyama N. Importance of research on peptidylarginine deiminase and citrullinated proteins in age-related disease. Geriatr Gerontol Int 2010; 10 Suppl 1:S53-8. [DOI: 10.1111/j.1447-0594.2010.00593.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Louw C, Gordon A, Johnston N, Mollatt C, Bradley G, Whiteley CG. Arginine deiminases: Therapeutic tools in the etiology and pathogenesis of Alzheimer's disease. J Enzyme Inhib Med Chem 2008; 22:121-6. [PMID: 17373558 DOI: 10.1080/14756360600990829] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
There is, at present, no definitive pre-mortem diagnostic tool for Alzheimer's disease, (AD) which relates to a poor understanding of its etiology. Brains of AD patients contain large amounts of the toxic plaque-forming beta-amyloid1-42 fragment in addition to elevated concentrations of the amino acid L-arginine. This work proposes that lowering levels of arginine in the astrocytes surrounding amyloid plaques may serve as a therapeutic tool in this neurodegenerative disorder. Arginine deiminase (ADI), from Pseudomonas aeruginosa, and peptidylarginine deiminase [PAD II], from bovine brain, are inhibited by amyloid peptides that contain arginine (amyloid1-42) and those that have no arginine (amyloid12-28/22-35). Enhanced activity of PAD II is noted with free L-arginine.
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Affiliation(s)
- Cassandra Louw
- Department of Biochemistry, Microbiology and Biotechnology Rhodes University, Grahamstown, South Africa
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11
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Musse AA, Polverini E, Raijmakers R, Harauz G. Kinetics of human peptidylarginine deiminase 2 (hPAD2) — Reduction of Ca2+ dependence by phospholipids and assessment of proposed inhibition by paclitaxel side chains. Biochem Cell Biol 2008; 86:437-47. [DOI: 10.1139/o08-124] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Multiple sclerosis is a complex human neurodegenerative disease, characterized by the active destruction of the insulating myelin sheath around the axons in the central nervous system. The physical deterioration of myelin is mediated by hyperdeimination of myelin basic and other proteins, catalysed by the Ca2+-dependent enzyme peptidylarginine deiminase 2 (PAD2). Thus, inhibition of PAD2 may be of value in treatment of this disease. Here, we have first characterized the in vitro kinetic properties of the human peptidylarginine deiminase isoform 2 (hPAD2). Phosphatidylserine and phosphatidylcholine reduced its Ca2+ dependence by almost twofold. Second, we have explored the putative inhibitory action of the methyl ester side chain of paclitaxel (TSME), which shares structural features with a synthetic PAD substrate, viz., the benzoyl-l-arginine ethyl ester (BAEE). Using the known crystallographic structure of the homologous enzyme hPAD4 and in silico molecular docking, we have shown that TSME interacted strongly with the catalytic site, albeit with a 100-fold lower affinity than BAEE. Despite paclitaxel having previously been shown to inhibit hPAD2 in vitro, the side chain of paclitaxel alone did not inhibit this enzyme’s activity.
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Affiliation(s)
- Abdiwahab A. Musse
- Department of Molecular and Cellular Biology, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Dipartimento di Fisica and CNISM, Università di Parma, V. le Usberti, 7/A, 43100 Parma, Italy
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands
| | - Eugenia Polverini
- Department of Molecular and Cellular Biology, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Dipartimento di Fisica and CNISM, Università di Parma, V. le Usberti, 7/A, 43100 Parma, Italy
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands
| | - Reinout Raijmakers
- Department of Molecular and Cellular Biology, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Dipartimento di Fisica and CNISM, Università di Parma, V. le Usberti, 7/A, 43100 Parma, Italy
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands
| | - George Harauz
- Department of Molecular and Cellular Biology, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Dipartimento di Fisica and CNISM, Università di Parma, V. le Usberti, 7/A, 43100 Parma, Italy
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands
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12
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Jang B, Kim E, Choi JK, Jin JK, Kim JI, Ishigami A, Maruyama N, Carp RI, Kim YS, Choi EK. Accumulation of citrullinated proteins by up-regulated peptidylarginine deiminase 2 in brains of scrapie-infected mice: a possible role in pathogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1129-42. [PMID: 18787103 DOI: 10.2353/ajpath.2008.080388] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Peptidylarginine deiminases (PADs), which are a group of posttranslational modification enzymes, are involved in protein citrullination (deimination) by the conversion of peptidylarginine to peptidylcitrulline in a calcium concentration-dependent manner. Among the PADs, PAD2 is widely distributed in various tissues and is the only type that is expressed in brain. To elucidate the involvement of protein citrullination by PAD2 in the pathogenesis of brain-specific prion diseases, we examined the profiles of citrullinated proteins using the brains of scrapie-infected mice as a prion disease model. We found that, compared with controls, increased levels of citrullinated proteins of various molecular weights were detected in different brain sections of scrapie-infected mice. In support of this data, expression levels of PAD2 protein as well as its enzyme activity were significantly increased in brain sections of scrapie-infected mice, including hippocampus, brain stem, and striatum. Additionally, the expression levels of PAD2 mRNA were increased during scrapie infection. Moreover, PAD2 immunoreactivity was increased in scrapie-infected brains, with staining detected primarily in reactive astrocytes. Using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry, various citrullinated proteins were identified in the brains of scrapie-infected mice, including glial fibrillary acidic protein, myelin basic protein, enolases, and aldolases. This study suggests that accumulated citrullinated proteins and abnormal activation of PAD2 may function in the pathogenesis of prion diseases and serve as potential therapeutic targets.
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Affiliation(s)
- Byungki Jang
- Ilsong Institute of Life Science, Hallym University, Anyang, Republic of Korea
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13
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Asaga H, Ishigami A. Microglial expression of peptidylarginine deiminase 2 in the prenatal rat brain. Cell Mol Biol Lett 2007; 12:536-44. [PMID: 17579814 PMCID: PMC6275991 DOI: 10.2478/s11658-007-0025-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Accepted: 04/18/2007] [Indexed: 11/20/2022] Open
Abstract
Peptidylarginine deiminases (PADs) are Ca2t+-dependant post-translational modification enzymes that catalyze the citrullination of protein arginyl residues. PAD type 2 (PAD2) is thought to be involved in some processes of neurodegeneration and myelination in the central nervous system. In this study, we found PAD2-positive cells in rat cerebra in 19-to 21-day old embryos, i.e. at a developmental stage well before myelination begins. Most of the cells were microglial marker-positive cells found mainly in the prospective medulla, and others were microglial marker-negative cells found mainly in the prospective dentate gyrus of the hippocampus. The former seemed to be in an activated state as judged by morphological criteria. The specificity of the enzyme activity, immunoblotting and reverse transcriptase-polymerase chain reaction analyses revealed that these cells expressed PAD2 and not PAD1, PAD3 or PAD4. Our data is indicative of microglial expression of PAD2 in the prenatal developing cerebrum.
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Affiliation(s)
- Hiroaki Asaga
- Biological Science Laboratory, Meiji University, Suginami-ku, Tokyo, 168-8555, Japan.
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14
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Cham JL, Badoer E. Exposure to a hot environment can activate spinally projecting and nitrergic neurones in the lower brainstem in the rat. Exp Physiol 2007; 92:529-40. [PMID: 17329312 DOI: 10.1113/expphysiol.2006.036806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Reflex responses to hyperthermia include sweating, salivation and a redirection of blood flow from the viscera to the periphery, and involve changes in peripheral nerve activity mediated by the central nervous system (CNS), including specific areas of the ventral lower brainstem. The lower brainstem contains nitrergic neurones and neurones that project to intermediolateral cell column; however, it is not known whether these populations of neurones in the lower brainstem are activated following hyperthermia. The aims of the present study were to determine whether lower brainstem neurones activated by acute hyperthermia are nitrergic and/or whether they also project to the spinal cord. Retrogradely transported rhodamine-tagged beads were microinjected into the spinal cord. The rats were heated (environmental temperature 39 degrees C) for 1 h. Following perfusion/fixation, brain sections were processed to detect Fos (a marker of neuronal activation) and NADPH-diaphorase activity (a marker of nitrergic neurones). The results showed a significant increase in activated neurones in the mid-line (by fivefold), ventromedial (by eightfold) and ventrolateral lower brainstem (by ninefold). Some of these neurones were nitrergic, particularly in the ventromedial lower brainstem (5% of the activated neurones in this region were nitrergic). A small proportion of activated neurones were spinally projecting neurones (2-3% of activated neurones were spinally projecting). There were no triple-labelled neurones at any level of the lower brainstem examined. These findings indicate that only a small proportion of nitrergic neurones and spinally projecting neurones are activated by hyperthermia.
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Affiliation(s)
- Joo Lee Cham
- School of Medical Sciences, RMIT University, PO Box 71, Bundoora 3083, Melbourne, Victoria, Australia
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15
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Chavanas S, Méchin MC, Nachat R, Adoue V, Coudane F, Serre G, Simon M. Peptidylarginine deiminases and deimination in biology and pathology: relevance to skin homeostasis. J Dermatol Sci 2006; 44:63-72. [PMID: 16973334 DOI: 10.1016/j.jdermsci.2006.07.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 07/12/2006] [Indexed: 11/28/2022]
Abstract
Deimination corresponds to the transformation of arginine residues within a peptide sequence into citrulline residues. Catalyzed by peptidylarginine deiminases, it decreases the net positive charge of proteins, alters intra and intermolecular ionic interactions and probably the folding of target proteins. Deimination has recently been implicated in several physiological and pathological processes. Here, we describe the enzymes involved in this post-translational modification, focusing on their expression, location and roles in skin, as well as their known protein substrates in the epidermis and hair follicles. We discuss also the potential involvement of deimination in human diseases including cutaneous disorders.
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Affiliation(s)
- Stéphane Chavanas
- UMR 5165, CNRS-University Toulouse III, Faculty of Medicine Purpan, 37 allées J. Guesde, 31073 Toulouse, France
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16
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Harauz G, Musse AA. A Tale of Two Citrullines—Structural and Functional Aspects of Myelin Basic Protein Deimination in Health and Disease. Neurochem Res 2006; 32:137-58. [PMID: 16900293 DOI: 10.1007/s11064-006-9108-9] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2006] [Indexed: 02/03/2023]
Abstract
Myelin basic protein (MBP) binds to negatively charged lipids on the cytosolic surface of oligodendrocyte membranes and is responsible for adhesion of these surfaces in the multilayered myelin sheath. The pattern of extensive post-translational modifications of MBP is dynamic during normal central nervous system (CNS) development and during myelin degeneration in multiple sclerosis (MS), affecting its interactions with the myelin membranes and with other molecules. In particular, the degree of deimination (or citrullination) of MBP is correlated with the severity of MS, and may represent a primary defect that precedes neurodegeneration due to autoimmune attack. That the degree of MBP deimination is also high in early CNS development indicates that this modification plays major physiological roles in myelin assembly. In this review, we describe the structural and functional consequences of MBP deimination in healthy and diseased myelin.
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Affiliation(s)
- George Harauz
- Department of Molecular and Cellular Biology, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, Canada, N1G 2W1.
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17
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György B, Tóth E, Tarcsa E, Falus A, Buzás EI. Citrullination: a posttranslational modification in health and disease. Int J Biochem Cell Biol 2006; 38:1662-77. [PMID: 16730216 DOI: 10.1016/j.biocel.2006.03.008] [Citation(s) in RCA: 338] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/13/2006] [Accepted: 03/14/2006] [Indexed: 11/29/2022]
Abstract
Posttranslational modifications are chemical changes to proteins that take place after synthesis. One such modification, peptidylarginine to peptidylcitrulline conversion, catalysed by peptidylarginine deiminases, has recently received significant interest in biomedicine. Introduction of citrulline dramatically changes the structure and function of proteins. It has been implicated in several physiological and pathological processes. Physiological processes include epithelial terminal differentiation, gene expression regulation, and apoptosis. Rheumatoid arthritis, multiple sclerosis, and Alzheimer's disease are examples of human diseases where protein citrullination involvement has been demonstrated. In this review, we discuss our current understanding on the importance of protein deimination in these processes. We describe the enzymes catalyzing the reaction, as well as their known protein substrates. We review the citrullinated peptide epitopes that are proposed as disease markers, specifically recognized in certain human autoimmune disorders. The potential autopathogenic role of citrullinated epitopes is also discussed.
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Affiliation(s)
- Bence György
- Department of Genetics, Cell- and Immunobiology, Semmelweis University, Budapest, Hungary
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Ishigami A, Ohsawa T, Hiratsuka M, Taguchi H, Kobayashi S, Saito Y, Murayama S, Asaga H, Toda T, Kimura N, Maruyama N. Abnormal accumulation of citrullinated proteins catalyzed by peptidylarginine deiminase in hippocampal extracts from patients with Alzheimer's disease. J Neurosci Res 2005; 80:120-8. [PMID: 15704193 DOI: 10.1002/jnr.20431] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Citrullinated proteins are the products of a posttranslational process in which arginine residues undergo modification into citrulline residues when catalyzed by peptidylarginine deiminases (PADs) in a calcium ion-dependent manner. In our previous report, PAD2 expressed mainly in the rat cerebrum became activated early in the neurodegenerative process. To elucidate the involvement of protein citrullination in human neuronal degeneration, we examined whether citrullinated proteins are produced during Alzheimer's disease (AD). By Western blot analysis with antimodified citrulline antibody, citrullinated proteins of varied molecular weights were detected in hippocampal tissues from patients with AD but not normal humans. Two of the citrullinated proteins were identified as vimentin and glial fibrillary acidic protein (GFAP) by using two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. Interestingly, PAD2 was detected in hippocampal extracts from AD and normal brains, but the amount of PAD2 in the AD tissue was markedly greater. Histochemical analysis revealed citrullinated proteins throughout the hippocampus, especially in the dentate gyrus and stratum radiatum of CA1 and CA2 areas. However, no citrullinated proteins were detected in the normal hippocampus. PAD2 immunoreactivity was also ubiquitous throughout both the AD and the normal hippocampal areas. PAD2 enrichment coincided well with citrullinated protein positivity. Double immunofluorescence staining revealed that citrullinated protein- and PAD2-positive cells also coincided with GFAP-positive cells, but not all GFAP-positive cells were positive for PAD2. As with GFAP, which is an astrocyte-specific marker protein, PAD2 is distributed mainly in astrocytes. These collective results, the abnormal accumulation of citrullinated proteins and abnormal activation of PAD2 in hippocampi of patients with AD, strongly suggest that PAD has an important role in the onset and progression of AD and that citrullinated proteins may become a useful marker for human neurodegenerative diseases.
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Affiliation(s)
- Akihito Ishigami
- Department of Molecular Pathology, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo, Japan.
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19
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Nijenhuis S, Zendman AJW, Vossenaar ER, Pruijn GJM, vanVenrooij WJ. Autoantibodies to citrullinated proteins in rheumatoid arthritis: clinical performance and biochemical aspects of an RA-specific marker. Clin Chim Acta 2005; 350:17-34. [PMID: 15530456 DOI: 10.1016/j.cccn.2004.07.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2004] [Revised: 06/30/2004] [Accepted: 07/15/2004] [Indexed: 12/01/2022]
Abstract
Rheumatoid arthritis (RA) is a common, systemic autoimmune disease of which the exact etiology is not known. In the past 10 years, substantial progress has been made in the identification of the antigens specifically recognized by the autoantibodies of RA patients. A central factor in this respect is citrullination, a form of post-translational modification that is strongly associated with autoimmunity in RA. Here, we summarize and discuss our current knowledge on (i) autoantibody systems in RA, (ii) the occurrence of peptidylarginine deiminases and (iii) citrullinated proteins in natural and diseased environments, and (iv) genetic factors involved in RA that may influence the generation and presentation of citrullinated proteins and the resulting antibody production against these modified proteins. Citrullination of proteins may play a key role in the initiation and/or the progression of RA. The onset of citrulline-specific autoimmunity in RA is probably mediated by both environmental and genetic factors, and future studies will learn whether therapeutic intervention at the level of citrullination may provide new possibilities to treat RA.
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Affiliation(s)
- Suzanne Nijenhuis
- Department of Biochemistry 161, Radboud University Nijmegen, PO Box 9101, NL-6500 HB Nijmegen, The Netherlands
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20
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Sambandam T, Belousova M, Accaviti-Loper MA, Blanquicett C, Guercello V, Raijmakers R, Nicholas AP. Increased peptidylarginine deiminase type II in hypoxic astrocytes. Biochem Biophys Res Commun 2004; 325:1324-9. [PMID: 15555572 DOI: 10.1016/j.bbrc.2004.10.173] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Indexed: 10/26/2022]
Abstract
Peptidylarginine deiminase type II (PAD 2) is the primary enzyme responsible for conversion of protein bound arginine to citrulline in the central nervous system. Evidence suggests that glial fibrillary acidic protein (GFAP), the main intermediate filament in astrocytes, is deiminated, but not much is known regarding factors that control this enzymatic reaction. The present study demonstrated that PAD 2 activity (as determined by Western blot analysis of citrullinated GFAP isoforms) was increased in human cultured astrocytes by hypoxic conditions. PAD 2 mRNA increased markedly during the first 2h of hypoxia, but using a single chain antibody against human PAD 2 produced from the ETH-2 phage library, it took approximately 8h of hypoxia to see marked increases in PAD 2 protein. Thus, this is the first report to demonstrate a measurable response in the amounts of PAD 2 mRNA, protein and activity in human astrocytes by prolonged hypoxic exposure.
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Affiliation(s)
- Thiagarajan Sambandam
- Department of Neurology, University of Alabama at Birmingham, School of Medicine, Birmingham, AL 35294, USA
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21
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Ahmed MM, Hoshino H, Chikuma T, Yamada M, Kato T. Effect of memantine on the levels of glial cells, neuropeptides, and peptide-degrading enzymes in rat brain regions of ibotenic acid-treated alzheimer's disease model. Neuroscience 2004; 126:639-49. [PMID: 15183513 DOI: 10.1016/j.neuroscience.2004.04.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2004] [Indexed: 02/06/2023]
Abstract
It has been implicated that glia activation plays a critical role in the progression of Alzheimer's disease (AD). However, the precise mechanism of glia activation is not clearly understood yet. In our present studies, we confirmed our previous results where change the levels of neuropeptides and peptidases in ibotenic acid (IBO) infusion into the rat nucleus basalis magnocellularis, an animal model of AD. Furthermore, we extended our study to investigate a possible protection effect of co-administration on the changes of neuropeptides, and neuronal and glial cells in IBO-infused rat brain by memantine treatment. The levels of substance P and somatostatin were decreased in the striatum and frontal cortex 1 week after IBO infusion, and recovered to the control level by memantine treatment, indicating the involvement of neuropeptides in AD pathology. Furthermore, the immunohistochemical and enzymatic studies of GFAP and CD 11b, and peptidylarginine deiminase, markers of glia, in the striatum and frontal cortex showed the increase in IBO-treated rat brain as compared with controls, while co-administration of memantine and IBO no increase of astrocytes and microglia activation was observed. The present biochemical and immunohistochemical results suggest that glia activation might play an important role to the pathology of AD, and correlate with the changes of neuropeptide levels in AD brain that is recovered by memantine treatment.
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Affiliation(s)
- M M Ahmed
- Laboratory of Natural Information Science, Graduate School of Integrated Science, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan
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22
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Vossenaar ER, Zendman AJW, van Venrooij WJ, Pruijn GJM. PAD, a growing family of citrullinating enzymes: genes, features and involvement in disease. Bioessays 2004; 25:1106-18. [PMID: 14579251 DOI: 10.1002/bies.10357] [Citation(s) in RCA: 705] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Peptidylarginine deiminase (PAD, EC 3.5.3.15) enzymes catalyze the conversion of protein-bound arginine to citrulline. This post-translational modification may have a big impact on the structure and function of the target protein. In this review, we will discuss the effects of citrullination and its involvement in several human diseases, including rheumatoid arthritis and multiple sclerosis. So far, four isotypes of PAD have been described in mammals. We describe the existence of PAD in non-mammalian vertebrates and the existence of a fifth mammalian PAD. In addition, tissue-specific expression, genomic organization and evolutionary conservation of the different PAD isotypes will be discussed in detail. This article contains supplementary material which may be viewed at the BioEssays website at http://www.interscience.wiley.com/jpages/0265-9247/suppmat/2003/25/v25.1106.html.
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Affiliation(s)
- Erik R Vossenaar
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands.
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23
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Nicholas AP, Sambandam T, Echols JD, Tourtellotte WW. Increased citrullinated glial fibrillary acidic protein in secondary progressive multiple sclerosis. J Comp Neurol 2004; 473:128-36. [PMID: 15067723 DOI: 10.1002/cne.20102] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In this study, we demonstrate that grossly unaffected white matter from secondary progressive multiple sclerosis (SP-MS) patients is heavily citrullinated, as compared to normal white matter from control patients. Citrullination was most pronounced at plaque interfaces and was shown to colocalize with glial fibrillary acidic protein (GFAP)-immunoreactivity using dual color immunofluorescence. In contrast, the plaques themselves weakly stained for citrullinated proteins compared to control white matter and usually contained a blood vessel with surrounding astrocytes that were positive both for citrullinated proteins and GFAP. In SP-MS brain samples, but not in normal brains, long fibers of colocalized GFAP- and citrullinated proteins extended into the gray matter. Increased numbers of astrocytes containing citrullinated proteins and GFAP were also present at the junction between the gray and white matter in SP-MS brains. Western blot analysis of acidic brain proteins from nonplaque-containing white matter showed upregulation of multiple citrullinated GFAP proteins in SP-MS brains as compared to controls. Our results demonstrate that increased amounts of citrullinated GFAP are present in SP-MS brains, but also shows that these proteins are present in areas of MS brains that were grossly normal appearing. These data raise the possibility that citrullination of GFAP contributes to the pathophysiology of MS.
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Affiliation(s)
- Anthony P Nicholas
- Department of Neurology, University of Alabama at Birmingham and the Birmingham Veterans Administration Medical Center, Birmingham, Alabama 35249-7340, USA.
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24
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Nicholas AP, King JL, Sambandam T, Echols JD, Gupta KB, McInnis C, Whitaker JN. Immunohistochemical localization of citrullinated proteins in adult rat brain. J Comp Neurol 2003; 459:251-66. [PMID: 12655508 DOI: 10.1002/cne.10607] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
By using hybridoma technology, an IgM monoclonal antibody (F95) against multiple citrullinated synthetic and natural peptides was recently developed and used to stain immunohistochemically subsets of astrocytes and myelin basic protein (MBP) from selected regions of human brain (Nicholas and Whitaker [2002] Glia 37:328-336). With this antibody, the present study provides a more detailed localization of citrullinated epitopes in the central nervous system (CNS) by examining immunohistochemical staining patterns for F95 in the normal adult rat brain. Thus, immunohistochemical labeling for citrullinated epitopes was seen in white matter areas consistent with myelin staining; however, in general, it was more prominent and uniform in the caudal CNS (spinal cord, medulla oblongata, pons, and cerebellum) than in more rostral areas. F95 staining was also seen in cells and fibers often intimately associated with blood vessels and/or ventricular surfaces. By using dual-color immunofluorescence, the vast majority of this latter staining was colocalized within a subset of astrocytes also immunoreactive for glial fibrillary acidic protein (GFAP). By using Western blot analysis of rat brain proteins, multiple GFAP- and MBP-immunoreactive proteins and peptide fragments were seen, and many of them were also reactive with the F95 antibody. Thus, the present study not only demonstrates that citrullinated epitopes in normal rat brain are most concentrated in subsets of myelin and astrocytes but also provides evidence that GFAP, like MBP, may be present as multiple citrullinated isoforms.
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Affiliation(s)
- Anthony P Nicholas
- Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama 35249-7340, USA.
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25
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Keilhoff G, Wolf G. Citrulline immunohistochemistry may not necessarily identify nitric oxide synthase activity: the pitfall of peptidylarginine deiminase. Nitric Oxide 2003; 8:31-8. [PMID: 12586539 DOI: 10.1016/s1089-8603(02)00130-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nitric oxide synthase (NOS) converts L-arginine as a substrate to form nitric oxide and the "by-product" citrulline. To characterize NOS activity in the nervous tissue at the single-cell level, citrulline immunostaining is considered to be a suitable means of working on the principle that in brain tissue, due to the incomplete urea cycle, citrulline is produced exclusively by NOS. This assumption is correct for free citrulline but it does not consider the conversion of arginine to citrulline residues of proteins by the calcium-dependent peptidylarginine deiminase (PAD). Using a polyclonal antiserum against citrulline we observed in cerebellar cell cultures immunopositivity in a few, mostly NOS-positive, neurons, in activated microglia, and in oligodendroglia (which under control conditions are in doubt to be able to express NOS), but not in astroglia. Treatment with the excitotoxin kainate substantially enhanced the staining intensity for citrulline in neurons and glial cells. To distinguish between free (NOS-related) and protein-bound (PAD-related) citrulline we blocked NOS activity by 7-nitroindazole or L-N5-(1-iminoethyl)lysine. The results provide evidence that citrulline immunolabeling results partly from PAD-mediated protein citrullination, enhanced pathophysiologically under stimulated conditions by exposure to kainate. Our immunocytochemical observations were corroborated by Western blot analysis showing several bands of citrulline-positive proteins, whose number and staining intensity depended on kainate treatment and calcium ions.
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Affiliation(s)
- Gerburg Keilhoff
- Institute of Medical Neurobiology, Otto-von-Guericke University of Magdeburg, Leipziger Strasse 44, D-39120 Magdeburg, Germany.
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26
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Asaga H, Akiyama K, Ohsawa T, Ishigami A. Increased and type II-specific expression of peptidylarginine deiminase in activated microglia but not hyperplastic astrocytes following kainic acid-evoked neurodegeneration in the rat brain. Neurosci Lett 2002; 326:129-32. [PMID: 12057845 DOI: 10.1016/s0304-3940(02)00334-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Peptidylarginine deiminases (PADs) are a group of posttranslational modification enzymes that convert protein arginine residues to citrulline residues. In the rat cerebrum, the type II PAD is thought to be expressed mainly in glial cells, especially astrocytes, and to become activated early in the neurodegenerative process. To determine whether hyperplastic glial cells express PAD type II, we examined the rat brain after kainic acid-evoked neurodegeneration. Western blot and reverse transcriptase-polymerase chain reaction analyses revealed increased and type II-specific expression of PAD in the brain at 4-7 days after kainate administration. Immunocytochemically, no PAD type II immunoreactivity was observed in the glial fibrillary acidic protein-positive astrocytes, but such immunoreactivity was present coincident with a microglial marker recognized by Bandeiraea simplicifolia isolectin B4 in the damaged regions. These results clearly indicate that PAD type II is specifically and abundantly expressed in activated microglial cells and suppressed in hyperplastic astrocytes following neurodegeneration.
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Affiliation(s)
- Hiroaki Asaga
- Department of Bioactivity Regulation, Tokyo Metropolitan Institute of Gerontology, Toyko 173-0015, Japan.
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27
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Nicholas AP, Whitaker JN. Preparation of a monoclonal antibody to citrullinated epitopes: Its characterization and some applications to immunohistochemistry in human brain. Glia 2002. [DOI: 10.1002/glia.10039] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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28
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Asaga H, Ishigami A. Protein deimination in the rat brain after kainate administration: citrulline-containing proteins as a novel marker of neurodegeneration. Neurosci Lett 2001; 299:5-8. [PMID: 11166924 DOI: 10.1016/s0304-3940(00)01735-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Peptidylarginine deiminases (PADs) are a group of enzymes that convert protein arginine residues to citrulline residues in a Ca2+-dependent manner. In the central nervous system, PAD type II localizes in glial cells, but its biological role is little understood. We examined the timing and region dependence of protein deimination in the rat cerebrum after a systemic injection of kainic acid (KA). Citrulline-containing proteins were consistently found in neurodegenerating regions. Western blot analyses showed deimination of numerous proteins in a broad-molecular-weight range. By immunocytochemical scrutiny, deiminated protein-positive astrocytes were found at 2 h after KA administration, and they increased in number until the 6 h. Furthermore, shrunken neurons became deiminated protein-positive at 12-24 h. These data suggest that PAD type II becomes activated in regions undergoing neurodegeneration and functions to deiminate various proteins. Therefore, citrulline-containing proteins seem to be a useful marker of acute neurodegeneration.
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Affiliation(s)
- H Asaga
- Department of Bioactivity Regulation, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan.
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29
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Murphy S, Simmons ML, Agullo L, Garcia A, Feinstein DL, Galea E, Reis DJ, Minc-Golomb D, Schwartz JP. Synthesis of nitric oxide in CNS glial cells. Trends Neurosci 1993; 16:323-8. [PMID: 7691008 DOI: 10.1016/0166-2236(93)90109-y] [Citation(s) in RCA: 504] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Attention has focused on particular neurons as the source of nitric oxide (NO) within the parenchyma of the CNS. In contrast, glial cells have been viewed mainly as potential reservoirs of L-arginine, the substrate for nitric oxide synthase (NOS), and as likely targets for neuronally derived NO because of their proximity and their expression of soluble guanylyl cyclase (sGC). However, it is becoming evident that astrocytes display both constitutive and inducible NOS activity under various conditions, and that activated microglia express an inducible NOS. The NO-producing capacity of oligodendrocytes is not yet known. Glial-derived NO has significant implications for CNS pathophysiology, given the anatomical location and abundance of these cells, and the wide variety of potential interactions that NO can have with cellular biochemistry. Our intention here is to evaluate the evidence for NO production from non-neuronal CNS sources and thus prompt discussion about potential 'nitrinergic' roles for glial cells.
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Affiliation(s)
- S Murphy
- Dept of Pharmacology, University of Iowa College of Medicine, Iowa City 52242
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