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Wischnewski S, Thäwel T, Ikenaga C, Kocharyan A, Lerma-Martin C, Zulji A, Rausch HW, Brenner D, Thomas L, Kutza M, Wick B, Trobisch T, Preusse C, Haeussler M, Leipe J, Ludolph A, Rosenbohm A, Hoke A, Platten M, Weishaupt JH, Sommer CJ, Stenzel W, Lloyd TE, Schirmer L. Cell type mapping of inflammatory muscle diseases highlights selective myofiber vulnerability in inclusion body myositis. NATURE AGING 2024; 4:969-983. [PMID: 38834884 PMCID: PMC11257986 DOI: 10.1038/s43587-024-00645-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 05/03/2024] [Indexed: 06/06/2024]
Abstract
Inclusion body myositis (IBM) is the most prevalent inflammatory muscle disease in older adults with no effective therapy available. In contrast to other inflammatory myopathies such as subacute, immune-mediated necrotizing myopathy (IMNM), IBM follows a chronic disease course with both inflammatory and degenerative features of pathology. Moreover, causal factors and molecular drivers of IBM progression are largely unknown. Therefore, we paired single-nucleus RNA sequencing with spatial transcriptomics from patient muscle biopsies to map cell-type-specific drivers underlying IBM pathogenesis compared with IMNM muscles and noninflammatory skeletal muscle samples. In IBM muscles, we observed a selective loss of type 2 myonuclei paralleled by increased levels of cytotoxic T and conventional type 1 dendritic cells. IBM myofibers were characterized by either upregulation of cell stress markers featuring GADD45A and NORAD or protein degradation markers including RNF7 associated with p62 aggregates. GADD45A upregulation was preferentially seen in type 2A myofibers associated with severe tissue inflammation. We also noted IBM-specific upregulation of ACHE encoding acetylcholinesterase, which can be regulated by NORAD activity and result in functional denervation of myofibers. Our results provide promising insights into possible mechanisms of myofiber degeneration in IBM and suggest a selective type 2 fiber vulnerability linked to genomic stress and denervation pathways.
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Grants
- R01 AR076390 NIAMS NIH HHS
- U41 HG002371 NHGRI NIH HHS
- European Research Council (DecOmPress ERC StG 950584), German Research Foundation grant (SCHI 1330/2-1, SCHI 1330/4-1, SCHI 1330/6-1, GRK 2727, SPP 2395), Hertie Foundation (P1180016), National Multiple Sclerosis Society (RFA-2203-39300, PA-2002-36405)
- The Myositis Association (90097118)
- German Cancer Aid
- National Human Genome Research Institute (5U41HG002371)
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01-AR076390), Muscular Dystrophy Association (MDA630399), The Peter and Carmen Lucia Buck Foundation, The Peter Frampton Myositis Research Fund
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Affiliation(s)
- Sven Wischnewski
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Thomas Thäwel
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Chiseko Ikenaga
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Anna Kocharyan
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Celia Lerma-Martin
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Amel Zulji
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Hans-Werner Rausch
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - David Brenner
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Department of Neurology, University of Ulm, Ulm, Germany
| | - Leonie Thomas
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Michael Kutza
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Brittney Wick
- Genomics Institute, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Tim Trobisch
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Corinna Preusse
- Department of Neuropathology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | | | - Jan Leipe
- Division of Rheumatology, Department of Medicine V, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Albert Ludolph
- Department of Neurology, University of Ulm, Ulm, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Ulm, Germany
| | | | - Ahmet Hoke
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael Platten
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- DKTK Clinical Cooperation Unit Neuroimmunology and Brain Tumor Immunology, German Cancer Research Center, Heidelberg, Germany
- Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Jochen H Weishaupt
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Clemens J Sommer
- Institute for Neuropathology, University Medical Center, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Werner Stenzel
- Department of Neuropathology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Thomas E Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA.
| | - Lucas Schirmer
- Department of Neurology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
- Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
- Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
- Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany.
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The NMJ as a model synapse: New perspectives on formation, synaptic transmission and maintenance: Acetylcholinesterase at the neuromuscular junction. Neurosci Lett 2020; 735:135157. [PMID: 32540360 DOI: 10.1016/j.neulet.2020.135157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 12/28/2022]
Abstract
Acetylcholinesterase (AChE) is an essential enzymatic component of the neuromuscular junction where it is responsible for terminating neurotransmission by the cholinergic motor neurons. The enzyme at the neuromuscular junction (NMJ) is contributed primarily by the skeletal muscle where it is produced at higher levels in the post-synaptic region of the fibers. The major form of AChE at the NMJ is a large asymmetric form consisting of three tetramers covalently attached to a three-stranded collagen-like tail which is responsible for anchoring it to the synaptic basal lamina. Its location and expression is regulated to a large extent by the motor neurons and occurs at the transcriptional, translational and post-translational levels. While its expression can be quite rapid in tissue cultured cells, its half-life in vivo appears to be quite long, about three weeks, although more rapidly turning over pools have been described. Finally the essential nature of this enzyme is underscored by the fact that no naturally occurring null mutations of the catalytic subunit have been described in higher organisms and the few dozen humans carrying mutations in the collagen tail responsible for anchoring the enzyme at the NMJ are severely affected.
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3
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Rotundo RL. Biogenesis, assembly and trafficking of acetylcholinesterase. J Neurochem 2017; 142 Suppl 2:52-58. [PMID: 28326552 PMCID: PMC5550332 DOI: 10.1111/jnc.13982] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 01/31/2017] [Indexed: 11/29/2022]
Abstract
Acetylcholinesterase (AChE) is expressed as several homomeric and heterooligomeric forms in a wide variety of tissues such as neurons in the central and peripheral nervous systems and their targets including skeletal muscle, endocrine and exocrine glands. In addition, glycolipid-anchored forms are expressed in erythropoietic and lymphopoietic cells. While transcriptional and post-transcriptional regulation is important for determining which AChE oligomeric forms are expressed in a given tissue, translational and post-translational regulatory mechanisms at the level of protein folding, assembly and sorting play equally important roles in assuring that the AChE molecules reach their intended sites on the cell surface in the appropriate numbers. This brief review will focus on the latter events in the cell with the goal of providing novel therapeutic interventional strategies for the treatment of organophosphate and carbamate pesticide and nerve agent exposure. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.
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Affiliation(s)
- Richard L Rotundo
- Department of Cell Biology and Neuroscience Program, University of Miami Miller School of Medicine, Miami, Florida, USA
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4
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Zhuang Q, Young A, Callam CS, McElroy CA, Ekici ÖD, Yoder RJ, Hadad CM. Efforts toward treatments against aging of organophosphorus-inhibited acetylcholinesterase. Ann N Y Acad Sci 2016; 1374:94-104. [PMID: 27327269 DOI: 10.1111/nyas.13124] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 11/26/2022]
Abstract
Aging is a dealkylation reaction of organophosphorus (OP)-inhibited acetylcholinesterase (AChE). Despite many studies to date, aged AChE cannot be reactivated directly by traditional pyridinium oximes. This review summarizes strategies that are potentially valuable in the treatment against aging in OP poisoning. Among them, retardation of aging seeks to lower the rate of aging through the use of AChE effectors. These drugs should be administered before AChE is completely aged. For postaging treatment, realkylation of aged AChE by appropriate alkylators may pave the way for oxime treatment by neutralizing the oxyanion at the active site of aged AChE. The other two strategies, upregulation of AChE expression and introduction of exogenous AChE, cannot resurrect aged AChE but may compensate for lowered active AChE levels by in situ production or external introduction of active AChE. Upregulation of AChE expression can be triggered by some peptides. Sources of exogenous AChE can be whole blood or purified AChE, either from human or nonhuman species.
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Affiliation(s)
- Qinggeng Zhuang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Amneh Young
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Christopher S Callam
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Craig A McElroy
- College of Pharmacy, The Ohio State University, Columbus, Ohio
| | - Özlem Dogan Ekici
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio.,Department of Chemistry and Biochemistry, The Ohio State University-Newark, Newark, Ohio
| | - Ryan J Yoder
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio.,Department of Chemistry and Biochemistry, The Ohio State University-Marion, Marion, Ohio
| | - Christopher M Hadad
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
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5
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Ruiz CA, Rossi SG, Rotundo RL. Rescue and Stabilization of Acetylcholinesterase in Skeletal Muscle by N-terminal Peptides Derived from the Noncatalytic Subunits. J Biol Chem 2015; 290:20774-20781. [PMID: 26139603 PMCID: PMC4543640 DOI: 10.1074/jbc.m115.653741] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/29/2015] [Indexed: 11/06/2022] Open
Abstract
The vast majority of newly synthesized acetylcholinesterase (AChE) molecules do not assemble into catalytically active oligomeric forms and are rapidly degraded intracellularly by the endoplasmic reticulum-associated protein degradation pathway. We have previously shown that AChE in skeletal muscle is regulated in part post-translationally by the availability of the noncatalytic subunit collagen Q, and others have shown that expression of a 17-amino acid N-terminal proline-rich attachment domain of collagen Q is sufficient to promote AChE tetramerization in cells producing AChE. In this study we show that muscle cells, or cell lines expressing AChE catalytic subunits, incubated with synthetic proline-rich attachment domain peptides containing the endoplasmic reticulum retrieval sequence KDEL take up and retrogradely transport them to the endoplasmic reticulum network where they induce assembly of AChE tetramers. The peptides act to enhance AChE folding thereby rescuing them from reticulum degradation. This enhanced folding efficiency occurs in the presence of inhibitors of protein synthesis and in turn increases total cell-associated AChE activity and active tetramer secretion. Pulse-chase studies of isotopically labeled AChE molecules show that the enzyme is rescued from intracellular degradation. These studies provide a mechanistic explanation for the large scale intracellular degradation of AChE previously observed and indicate that simple peptides alone can increase the production and secretion of this critical synaptic enzyme in muscle tissue.
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Affiliation(s)
- Carlos A Ruiz
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Susana G Rossi
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Richard L Rotundo
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida 33136; Department of Neuroscience Program, University of Miami Miller School of Medicine, Miami, Florida 33136.
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6
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Blotnick E, Hamra-Amitai Y, Wald C, Brenner T, Anglister L. Changes in acetylcholinesterase in experimental autoimmune myasthenia gravis and in response to treatment with a specific antisense. Eur J Neurosci 2012; 36:3077-85. [PMID: 22805122 DOI: 10.1111/j.1460-9568.2012.08218.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Controlled regulation of synaptic nicotinic acetylcholine receptors (AChRs) and acetylcholinesterase (AChE), together with maintenance of a dynamic balance between them, is a requirement for proper function of cholinergic synapses. In the present study we assessed whether pathological changes in AChR perturb this balance, and whether such changes can be corrected. We studied the influence of AChR loss, caused by experimental autoimmune myasthenia gravis (EAMG), on muscle AChE, as well as the reciprocal effect of an antisense targeted towards AChE on both AChR and AChE at the neuromuscular synapse. The extensor digitorum longus (EDL) muscles of EAMG Lewis rats were isolated, and AChE levels and isoform compositions were examined. Although AChE levels in the muscles of healthy and EAMG rats were similar, marked changes were observed in isoform composition. Healthy EDL muscles contained globular (G(1,2) , G(4) ) and asymmetric (primarily A(12) ) isoforms. G(1,2) -AChE was significantly reduced in EAMG muscles, whereas both G(4) - and A(12) -AChE remained unchanged. Treatment of EAMG rats with the antisense EN101 resulted in decreased total muscle AChE, with recovery in G(1,2) and reduction in A(12) -AChE. AChE/AChR ratios were determined at the neuromuscular junctions (NMJ). The decrease in AChR levels that occurred as the disease progressed resulted in a dramatic increase in this ratio, and a significant recovery towards normal ratios occurred after EN101 treatment. This improvement was primarily due to increased synaptic AChR content. Our findings emphasise the tight connection between AChR and AChE at the myasthenic NMJ, and the importance of the AChE/AChR ratio in maintaining the required cholinergic balance.
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Affiliation(s)
- Edna Blotnick
- Department of Medical Neurobiology, Institute for Medical Research, IMRIC, Hebrew University Medical School, Jerusalem, Israel
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7
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Protein-anchoring strategy for delivering acetylcholinesterase to the neuromuscular junction. Mol Ther 2012; 20:1384-92. [PMID: 22371845 DOI: 10.1038/mt.2012.34] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Acetylcholinesterase (AChE) at the neuromuscular junction (NMJ) is anchored to the synaptic basal lamina via a triple helical collagen Q (ColQ). Congenital defects of ColQ cause endplate AChE deficiency and myasthenic syndrome. A single intravenous administration of adeno-associated virus serotype 8 (AAV8)-COLQ to Colq(-/-) mice recovered motor functions, synaptic transmission, as well as the morphology of the NMJ. ColQ-tailed AChE was specifically anchored to NMJ and its amount was restored to 89% of the wild type. We next characterized the molecular basis of this efficient recovery. We first confirmed that ColQ-tailed AChE can be specifically targeted to NMJ by an in vitro overlay assay in Colq(-/-) mice muscle sections. We then injected AAV1-COLQ-IRES-EGFP into the left tibialis anterior and detected AChE in noninjected limbs. Furthermore, the in vivo injection of recombinant ColQ-tailed AChE protein complex into the gluteus maximus muscle of Colq(-/-) mice led to accumulation of AChE in noninjected forelimbs. We demonstrated for the first time in vivo that the ColQ protein contains a tissue-targeting signal that is sufficient for anchoring itself to the NMJ. We propose that the protein-anchoring strategy is potentially applicable to a broad spectrum of diseases affecting extracellular matrix molecules.
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8
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Chen VP, Luk WKW, Chan WKB, Leung KW, Guo AJY, Chan GKL, Xu SL, Choi RCY, Tsim KWK. Molecular Assembly and Biosynthesis of Acetylcholinesterase in Brain and Muscle: the Roles of t-peptide, FHB Domain, and N-linked Glycosylation. Front Mol Neurosci 2011; 4:36. [PMID: 22046147 PMCID: PMC3200509 DOI: 10.3389/fnmol.2011.00036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Accepted: 10/10/2011] [Indexed: 11/13/2022] Open
Abstract
Acetylcholinesterase (AChE) is responsible for the hydrolysis of the neurotransmitter, acetylcholine, in the nervous system. The functional localization and oligomerization of AChE T variant are depending primarily on the association of their anchoring partners, either collagen tail (ColQ) or proline-rich membrane anchor (PRiMA). Complexes with ColQ represent the asymmetric forms (A(12)) in muscle, while complexes with PRiMA represent tetrameric globular forms (G(4)) mainly found in brain and muscle. Apart from these traditional molecular forms, a ColQ-linked asymmetric form and a PRiMA-linked globular form of hybrid cholinesterases (ChEs), having both AChE and BChE catalytic subunits, were revealed in chicken brain and muscle. The similarity of various molecular forms of AChE and BChE raises interesting question regarding to their possible relationship in enzyme assembly and localization. The focus of this review is to provide current findings about the biosynthesis of different forms of ChEs together with their anchoring proteins.
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Affiliation(s)
- Vicky P Chen
- Division of Life Science, Center for Chinese Medicine, The Hong Kong University of Science and Technology Hong Kong, China
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9
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Pezzementi L, Krejci E, Chatonnet A, Selkirk ME, Matthews JB. A tetrameric acetylcholinesterase from the parasitic nematode Dictyocaulus viviparus associates with the vertebrate tail proteins PRiMA and ColQ. Mol Biochem Parasitol 2011; 181:40-8. [PMID: 22027027 DOI: 10.1016/j.molbiopara.2011.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 09/26/2011] [Accepted: 10/11/2011] [Indexed: 10/16/2022]
Abstract
Dictyocaulus viviparus causes a serious lung disease of cattle. Similar to other parasitic nematodes, D. viviparus possesses several acetylcholinesterase (AChE) genes, one of which encodes a putative neuromuscular AChE, which contains a tryptophan (W) amphiphilic tetramerization (WAT) domain at its C-terminus. In the current study, we describe the biochemical characterization of a recombinant version of this WAT domain-containing AChE. To assess if the WAT domain is biologically functional, we investigated the association of the recombinant enzyme with the vertebrate tail proteins, proline-rich membrane anchor (PRiMA) and collagen Q (ColQ), as well as the synthetic polypeptide poly-l-proline. The results indicate that the recombinant enzyme hydrolyzes acetylthiocholine preferentially and exhibits inhibition by excess substrate, a characteristic of AChEs but not butyrylcholinesterases (BChEs). The enzyme is inhibited by the AChE inhibitor, BW284c51, but not by the BChE inhibitors, ethopropazine or iso-OMPA. The enzyme is able to assemble into monomeric (G(1)), dimeric (G(2)), and tetrameric (G(4)) globular forms and can also associate with PRiMA and ColQ, which contain proline-rich attachment domains (PRADs). This interaction is likely to be mediated via WAT-PRAD interactions, as the enzyme also assembles into tetramers with the synthetic polypeptide poly-l-proline. These interactions are typical of AChE(T) subunits. This is the first demonstration of an AChE(T) from a parasitic nematode that can assemble into heterologous forms with vertebrate proteins that anchor the enzyme in cholinergic synapses. We discuss the implications of our results for this particular host/parasite system and for the evolution of AChE.
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Affiliation(s)
- Leo Pezzementi
- Department of Biology, Birmingham-Southern College, Birmingham, AL 35254, USA.
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10
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Chen VP, Choi RCY, Chan WKB, Leung KW, Guo AJY, Chan GKL, Luk WKW, Tsim KWK. The assembly of proline-rich membrane anchor (PRiMA)-linked acetylcholinesterase enzyme: glycosylation is required for enzymatic activity but not for oligomerization. J Biol Chem 2011; 286:32948-61. [PMID: 21795704 DOI: 10.1074/jbc.m111.261248] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetylcholinesterase (AChE) anchors onto cell membranes by a transmembrane protein PRiMA (proline-rich membrane anchor) as a tetrameric form in vertebrate brain. The assembly of AChE tetramer with PRiMA requires the C-terminal "t-peptide" in AChE catalytic subunit (AChE(T)). Although mature AChE is well known N-glycosylated, the role of glycosylation in forming the physiologically active PRiMA-linked AChE tetramer has not been studied. Here, several lines of evidence indicate that the N-linked glycosylation of AChE(T) plays a major role for acquisition of AChE full enzymatic activity but does not affect its oligomerization. The expression of the AChE(T) mutant, in which all N-glycosylation sites were deleted, together with PRiMA in HEK293T cells produced a glycan-depleted PRiMA-linked AChE tetramer but with a much higher K(m) value as compared with the wild type. This glycan-depleted enzyme was assembled in endoplasmic reticulum but was not transported to Golgi apparatus or plasma membrane.
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Affiliation(s)
- Vicky P Chen
- Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Hong Kong SAR, China
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11
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Jett DA. Finding new cures for neurological disorders: a possible fringe benefit of biodefense research? Sci Transl Med 2010; 2:23ps12. [PMID: 20375001 DOI: 10.1126/scitranslmed.3000752] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The National Institutes of Health (NIH) supports research about and the development of better therapies for treating exposure to toxic chemicals that could be used in a terrorist attack or released during an industrial accident. A review of recent research published by NIH investigators working in this field indicates that scientific advances in this area also have implications for reducing the burden of other neurological diseases and disorders. Some key examples discussed include studies on the development of therapeutic drugs to treat seizures and the neuropathology caused by chemical nerve agents, which may help find better cures for epilepsy, stroke, and neurodegenerative diseases.
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Affiliation(s)
- David A Jett
- NIH CounterACT Research, National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
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12
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Sigoillot SM, Bourgeois F, Legay C. Cholinesterases regulation in the absence of ColQ. Chem Biol Interact 2010; 187:84-9. [PMID: 20153305 DOI: 10.1016/j.cbi.2010.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 02/03/2010] [Accepted: 02/04/2010] [Indexed: 11/26/2022]
Abstract
Normal physiological activity of the neuromuscular junction (NMJ) requires that key molecules are clustered at the synapse. One of these molecules is acetylcholinesterase (AChE) that regulates acetylcholine levels. This enzyme exists under different isoforms but the predominant form at the NMJ is a collagen-tailed enzyme. The collagen associated to AChE (ColQ) fulfills two functions. It anchors and accumulates AChE in the extracellular matrix. Mutations in ColQ lead to faint or no activity of AChE in the synaptic cleft. As a consequence, normal NMJ functioning is impaired and myasthenic syndromes are observed in patients bearing these mutations. Here, we investigated the effects of ColQ deficiency on cholinesterases mRNA levels and cluster formation. We show that overexpression of AChE but not ColQ in muscle cells is sufficient to drive the formation of AChE clusters. The absence of ColQ in muscle cells in vitro and in vivo leads to an increase in AChE(R) and AChE(T) mRNAs, corresponding to two isoforms of AChE. However, AChE activity is decreased in the medium of ColQ-deficient cells suggesting that AChE secretion is impaired. Butyrylcholinesterase (BChE) mRNAs are also upregulated in vivo. Since AChE and BChE can associate with PRiMA, a membrane anchor, we explored the pattern of expression of PRiMA in vitro and in vivo. The level of PRiMA transcripts is downregulated in the absence of ColQ. Therefore, AChE, BChE and PRiMA mRNA level modifications found in the absence of ColQ cannot compensate for the physiological defects observed at the ColQ-deficient NMJs.
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Affiliation(s)
- Séverine M Sigoillot
- Laboratoire de biologie des jonctions neuromusculaires normales et pathologiques, Université Paris Descartes, INSERM U686, 45, rue des Saints Pères, 75270 Paris, France
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13
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Ruiz CA, Rotundo RL. Limiting role of protein disulfide isomerase in the expression of collagen-tailed acetylcholinesterase forms in muscle. J Biol Chem 2009; 284:31753-63. [PMID: 19758986 DOI: 10.1074/jbc.m109.038471] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The expression of acetylcholinesterase (AChE) in skeletal muscle is regulated by muscle activity; however, the underlying molecular mechanisms are incompletely understood. We show here that the expression of the synaptic collagen-tailed AChE form (ColQ-AChE) in quail muscle cultures can be regulated by muscle activity post-translationally. Inhibition of thiol oxidoreductase activity decreases expression of all active AChE forms. Likewise, primary quail myotubes transfected with protein disulfide isomerase (PDI) short hairpin RNAs showed a significant decrease of both the intracellular pool of all collagen-tailed AChE forms and cell surface AChE clusters. Conversely, overexpression of PDI, endoplasmic reticulum protein 72, or calnexin in muscle cells enhanced expression of all collagen-tailed AChE forms. Overexpression of PDI had the most dramatic effect with a 100% increase in the intracellular ColQ-AChE pool and cell surface enzyme activity. Moreover, the levels of PDI are regulated by muscle activity and correlate with the levels of ColQ-AChE and AChE tetramers. Finally, we demonstrate that PDI interacts directly with AChE intracellularly. These results show that collagen-tailed AChE form levels induced by muscle activity can be regulated by molecular chaperones and suggest that newly synthesized exportable proteins may compete for chaperone assistance during the folding process.
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Affiliation(s)
- Carlos A Ruiz
- Department of Cell Biology and Anatomy and the Neuroscience Program, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
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