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Weichert L, Düsedau HP, Fritzsch D, Schreier S, Scharf A, Grashoff M, Cebulski K, Michaelsen-Preusse K, Erck C, Lienenklaus S, Dunay IR, Kröger A. Astrocytes evoke a robust IRF7-independent type I interferon response upon neurotropic viral infection. J Neuroinflammation 2023; 20:213. [PMID: 37737190 PMCID: PMC10515022 DOI: 10.1186/s12974-023-02892-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 09/06/2023] [Indexed: 09/23/2023] Open
Abstract
BACKGROUND Type I interferons (IFN-I) are fundamental in controlling viral infections but fatal interferonopathy is restricted in the immune-privileged central nervous system (CNS). In contrast to the well-established role of Interferon Regulatory Factor 7 (IRF7) in the regulation of IFN-I response in the periphery, little is known about the specific function in the CNS. METHODS To investigate the role for IRF7 in antiviral response during neurotropic virus infection, mice deficient for IRF3 and IRF7 were infected systemically with Langat virus (LGTV). Viral burden and IFN-I response was analyzed in the periphery and the CNS by focus formation assay, RT-PCR, immunohistochemistry and in vivo imaging. Microglia and infiltration of CNS-infiltration of immune cells were characterized by flow cytometry. RESULTS Here, we demonstrate that during infection with the neurotropic Langat virus (LGTV), an attenuated member of the tick-borne encephalitis virus (TBEV) subgroup, neurons do not rely on IRF7 for cell-intrinsic antiviral resistance and IFN-I induction. An increased viral replication in IRF7-deficient mice suggests an indirect antiviral mechanism. Astrocytes rely on IRF7 to establish a cell-autonomous antiviral response. Notably, the loss of IRF7 particularly in astrocytes resulted in a high IFN-I production. Sustained production of IFN-I in astrocytes is independent of an IRF7-mediated positive feedback loop. CONCLUSION IFN-I induction in the CNS is profoundly regulated in a cell type-specific fashion.
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Affiliation(s)
- Loreen Weichert
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
- Innate Immunity and Infection, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Henning Peter Düsedau
- Institute of Inflammation and Neurodegeneration, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
| | - David Fritzsch
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
| | - Sarah Schreier
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
| | - Annika Scharf
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
- Innate Immunity and Infection, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Martina Grashoff
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
- Innate Immunity and Infection, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Kristin Cebulski
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
| | | | - Christian Erck
- Cellular Proteome Research, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Stefan Lienenklaus
- Institute for Laboratory Animal Science, Hanover Medical School, 30625, Hannover, Germany
| | - Ildiko Rita Dunay
- Institute of Inflammation and Neurodegeneration, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany
- Health Campus Immunology, Infectiology, and inflammation (GC-I3), Magdeburg, Germany
- Center for Behavioral Braun Science (CBBS), 39106, Magdeburg, Germany
| | - Andrea Kröger
- Molecular Microbiology Group, Institute of Medical Microbiology and Hospital Hygiene, Otto-von-Guericke-University Magdeburg, 39120, Magdeburg, Germany.
- Innate Immunity and Infection, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany.
- Health Campus Immunology, Infectiology, and inflammation (GC-I3), Magdeburg, Germany.
- Center for Behavioral Braun Science (CBBS), 39106, Magdeburg, Germany.
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2
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Hosseini S, van Ham M, Erck C, Korte M, Michaelsen-Preusse K. The role of α-tubulin tyrosination in controlling the structure and function of hippocampal neurons. Front Mol Neurosci 2022; 15:931859. [PMCID: PMC9627282 DOI: 10.3389/fnmol.2022.931859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubules (MTs) are central components of the neuronal cytoskeleton and play a critical role in CNS integrity, function, and plasticity. Neuronal MTs are diverse due to extensive post-translational modifications (PTMs), particularly detyrosination/tyrosination, in which the C-terminal tyrosine of α-tubulin is cyclically removed by a carboxypeptidase and reattached by a tubulin-tyrosine ligase (TTL). The detyrosination/tyrosination cycle of MTs has been shown to be an important regulator of MT dynamics in neurons. TTL-null mice exhibit impaired neuronal organization and die immediately after birth, indicating TTL function is vital to the CNS. However, the detailed cellular role of TTL during development and in the adult brain remains elusive. Here, we demonstrate that conditional deletion of TTL in the neocortex and hippocampus during network development results in a pathophysiological phenotype defined by incomplete development of the corpus callosum and anterior commissures due to axonal growth arrest. TTL loss was also associated with a deficit in spatial learning, impaired synaptic plasticity, and reduced number of spines in hippocampal neurons, suggesting that TTL also plays a critical role in hippocampal network development. TTL deletion after postnatal development, specifically in the hippocampus and in cultured hippocampal neurons, led to a loss of spines and impaired spine structural plasticity. This indicates a novel and important function of TTL for synaptic plasticity in the adult brain. In conclusion, this study reveals the importance of α-tubulin tyrosination, which defines the dynamics of MTs, in controlling proper network formation and suggests TTL-mediated tyrosination as a new key determinant of synaptic plasticity in the adult brain.
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Affiliation(s)
- Shirin Hosseini
- Department of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
- Research Group Neuroinflammation and Neurodegeneration, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Marco van Ham
- Research Group Cellular Proteome Research, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Christian Erck
- Research Group Cellular Proteome Research, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Martin Korte
- Department of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
- Research Group Neuroinflammation and Neurodegeneration, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Kristin Michaelsen-Preusse
- Department of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
- *Correspondence: Kristin Michaelsen-Preusse,
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Seiler LK, Phung NL, Nikolin C, Immenschuh S, Erck C, Kaufeld J, Haller H, Falk CS, Jonczyk R, Lindner P, Thoms S, Siegl J, Mayer G, Feederle R, Blume CA. An Antibody-Aptamer-Hybrid Lateral Flow Assay for Detection of CXCL9 in Antibody-Mediated Rejection after Kidney Transplantation. Diagnostics (Basel) 2022; 12:diagnostics12020308. [PMID: 35204399 PMCID: PMC8871475 DOI: 10.3390/diagnostics12020308] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 02/04/2023] Open
Abstract
Chronic antibody-mediated rejection (AMR) is a key limiting factor for the clinical outcome of a kidney transplantation (Ktx), where early diagnosis and therapeutic intervention is needed. This study describes the identification of the biomarker CXC-motif chemokine ligand (CXCL) 9 as an indicator for AMR and presents a new aptamer-antibody-hybrid lateral flow assay (hybrid-LFA) for detection in urine. Biomarker evaluation included two independent cohorts of kidney transplant recipients (KTRs) from a protocol biopsy program and used subgroup comparisons according to BANFF-classifications. Plasma, urine and biopsy lysate samples were analyzed with a Luminex-based multiplex assay. The CXCL9-specific hybrid-LFA was developed based upon a specific rat antibody immobilized on a nitrocellulose-membrane and the coupling of a CXCL9-binding aptamer to gold nanoparticles. LFA performance was assessed according to receiver operating characteristic (ROC) analysis. Among 15 high-scored biomarkers according to a neural network analysis, significantly higher levels of CXCL9 were found in plasma and urine and biopsy lysates of KTRs with biopsy-proven AMR. The newly developed hybrid-LFA reached a sensitivity and specificity of 71% and an AUC of 0.79 for CXCL9. This point-of-care-test (POCT) improves early diagnosis-making in AMR after Ktx, especially in KTRs with undetermined status of donor-specific HLA-antibodies.
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Affiliation(s)
- Lisa K. Seiler
- Institute of Technical Chemistry, Leibniz University Hannover, 30167 Hannover, Germany; (L.K.S.); (N.L.P.); (R.J.); (P.L.); (S.T.)
| | - Ngoc Linh Phung
- Institute of Technical Chemistry, Leibniz University Hannover, 30167 Hannover, Germany; (L.K.S.); (N.L.P.); (R.J.); (P.L.); (S.T.)
| | - Christoph Nikolin
- Institute of Transfusion Medicine and Transplant Engineering, Hannover Medical School, 30625 Hannover, Germany; (C.N.); (S.I.)
| | - Stephan Immenschuh
- Institute of Transfusion Medicine and Transplant Engineering, Hannover Medical School, 30625 Hannover, Germany; (C.N.); (S.I.)
| | - Christian Erck
- Helmholtz Centre for Infection Research, Cellular Proteome Research Group, 38124 Braunschweig, Germany;
| | - Jessica Kaufeld
- Department of Nephrology and Hypertension, Hannover Medical School, 30625 Hannover, Germany; (J.K.); (H.H.)
| | - Hermann Haller
- Department of Nephrology and Hypertension, Hannover Medical School, 30625 Hannover, Germany; (J.K.); (H.H.)
| | - Christine S. Falk
- Institute for Transplant Immunology, Hannover Medical School, 30625 Hannover, Germany;
| | - Rebecca Jonczyk
- Institute of Technical Chemistry, Leibniz University Hannover, 30167 Hannover, Germany; (L.K.S.); (N.L.P.); (R.J.); (P.L.); (S.T.)
| | - Patrick Lindner
- Institute of Technical Chemistry, Leibniz University Hannover, 30167 Hannover, Germany; (L.K.S.); (N.L.P.); (R.J.); (P.L.); (S.T.)
| | - Stefanie Thoms
- Institute of Technical Chemistry, Leibniz University Hannover, 30167 Hannover, Germany; (L.K.S.); (N.L.P.); (R.J.); (P.L.); (S.T.)
| | - Julia Siegl
- Chemical Biology & Chemical Genetics, Life and Medical Sciences (LIMES) Institute, University of Bonn, 53121 Bonn, Germany; (J.S.); (G.M.)
- Center of Aptamer Research & Development (CARD), University of Bonn, 53121 Bonn, Germany
| | - Günter Mayer
- Chemical Biology & Chemical Genetics, Life and Medical Sciences (LIMES) Institute, University of Bonn, 53121 Bonn, Germany; (J.S.); (G.M.)
- Center of Aptamer Research & Development (CARD), University of Bonn, 53121 Bonn, Germany
| | - Regina Feederle
- Monoclonal Antibody Core Facility, Institute for Diabetes and Obesity, Helmholtz-Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany;
| | - Cornelia A. Blume
- Institute of Technical Chemistry, Leibniz University Hannover, 30167 Hannover, Germany; (L.K.S.); (N.L.P.); (R.J.); (P.L.); (S.T.)
- Correspondence:
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4
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Volckmar J, Knop L, Hirsch T, Frentzel S, Erck C, van Ham M, Stegemann-Koniszewski S, Bruder D. Chemical Conjugation of a Purified DEC-205-Directed Antibody with Full-Length Protein for Targeting Mouse Dendritic Cells In Vitro and In Vivo. J Vis Exp 2021. [PMID: 33616089 DOI: 10.3791/62018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Targeted antigen delivery to cross-presenting dendritic cells (DC) in vivo efficiently induces T effector cell responses and displays a valuable approach in vaccine design. Antigen is delivered to DC via antibodies specific for endocytosis receptors such as DEC-205 that induce uptake, processing, and MHC class I- and II-presentation. Efficient and reliable conjugation of the desired antigen to a suitable antibody is a critical step in DC targeting and among other factors depends on the format of the antigen. Chemical conjugation of full-length protein to purified antibodies is one possible strategy. In the past, we have successfully established cross-linking of the model antigen ovalbumin (OVA) and a DEC-205-specific IgG2a antibody (αDEC-205) for in vivo DC targeting studies in mice. The first step of the protocol is the purification of the antibody from the supernatant of the NLDC (non-lymphoid dendritic cells)-145 hybridoma by affinity chromatography. The purified antibody is activated for chemical conjugation by sulfo-SMCC (sulfosuccinimidyl 4-[N-maleimidomethyl] cyclohexane-1-carboxylate) while at the same time the sulfhydryl-groups of the OVA protein are exposed through incubation with TCEP-HCl (tris (2-carboxyethyl) phosphine hydrochloride). Excess TCEP-HCl and sulfo-SMCC are removed and the antigen is mixed with the activated antibody for overnight coupling. The resulting αDEC-205/OVA conjugate is concentrated and freed from unbound OVA. Successful conjugation of OVA to αDEC-205 is verified by western blot analysis and enzyme-linked immunosorbent assay (ELISA). We have successfully used chemically crosslinked αDEC-205/OVA to induce cytotoxic T cell responses in the liver and to compare different adjuvants for their potential in inducing humoral and cellular immunity following in vivo targeting of DEC-205+ DC. Beyond that, such chemically coupled antibody/antigen conjugates offer valuable tools for the efficient induction of vaccine responses to tumor antigens and have been proven to be superior to classical immunization approaches regarding the prevention and therapy of various types of tumors.
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Affiliation(s)
- Julia Volckmar
- Immune Regulation Group, Helmholtz Centre for Infection Research; Infection Immunology Group, Institute of Medical Microbiology, Infection Prevention and Control, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg;
| | - Laura Knop
- Immune Regulation Group, Helmholtz Centre for Infection Research; Infection Immunology Group, Institute of Medical Microbiology, Infection Prevention and Control, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg; Institute for Molecular and Clinical Immunology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg
| | - Tatjana Hirsch
- Immune Regulation Group, Helmholtz Centre for Infection Research
| | - Sarah Frentzel
- Immune Regulation Group, Helmholtz Centre for Infection Research; Infection Immunology Group, Institute of Medical Microbiology, Infection Prevention and Control, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg
| | - Christian Erck
- Cellular Proteome Research, Helmholtz Centre for Infection Research
| | - Marco van Ham
- Cellular Proteome Research, Helmholtz Centre for Infection Research
| | - Sabine Stegemann-Koniszewski
- Immune Regulation Group, Helmholtz Centre for Infection Research; Infection Immunology Group, Institute of Medical Microbiology, Infection Prevention and Control, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg; Experimental Pneumology, University Hospital of Pneumology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg
| | - Dunja Bruder
- Immune Regulation Group, Helmholtz Centre for Infection Research; Infection Immunology Group, Institute of Medical Microbiology, Infection Prevention and Control, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg
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5
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Rodriguez Camargo DC, Tripsianes K, Buday K, Franko A, Göbl C, Hartlmüller C, Sarkar R, Aichler M, Mettenleiter G, Schulz M, Böddrich A, Erck C, Martens H, Walch AK, Madl T, Wanker EE, Conrad M, de Angelis MH, Reif B. The redox environment triggers conformational changes and aggregation of hIAPP in Type II Diabetes. Sci Rep 2017; 7:44041. [PMID: 28287098 PMCID: PMC5347123 DOI: 10.1038/srep44041] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 02/03/2017] [Indexed: 12/22/2022] Open
Abstract
Type II diabetes (T2D) is characterized by diminished insulin production and resistance of cells to insulin. Among others, endoplasmic reticulum (ER) stress is a principal factor contributing to T2D and induces a shift towards a more reducing cellular environment. At the same time, peripheral insulin resistance triggers the over-production of regulatory hormones such as insulin and human islet amyloid polypeptide (hIAPP). We show that the differential aggregation of reduced and oxidized hIAPP assists to maintain the redox equilibrium by restoring redox equivalents. Aggregation thus induces redox balancing which can assist initially to counteract ER stress. Failure of the protein degradation machinery might finally result in β-cell disruption and cell death. We further present a structural characterization of hIAPP in solution, demonstrating that the N-terminus of the oxidized peptide has a high propensity to form an α-helical structure which is lacking in the reduced state of hIAPP. In healthy cells, this residual structure prevents the conversion into amyloidogenic aggregates.
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Affiliation(s)
- Diana C Rodriguez Camargo
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Konstantinos Tripsianes
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, Brno 62500, Czech Republic
| | - Katalin Buday
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Andras Franko
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,German Center for Diabetes Research (DZD e.V.), Neuherberg 85764, Germany
| | - Christoph Göbl
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Christoph Hartlmüller
- Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Riddhiman Sarkar
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
| | - Michaela Aichler
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | | | - Michael Schulz
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Annett Böddrich
- Max-Delbrück-Center Berlin (MDC), Robert-Rössle-Str. 10, Berlin 13125, Germany
| | - Christian Erck
- Synaptic Systems GmbH, Rudolf-Wissell-Straße 28, Göttingen, 37079, Germany
| | - Henrik Martens
- Synaptic Systems GmbH, Rudolf-Wissell-Straße 28, Göttingen, 37079, Germany
| | - Axel Karl Walch
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Tobias Madl
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany.,Institute of Molecular Biology &Biochemistry, Center of Molecular Medicine, Medical University of Graz, Austria
| | - Erich E Wanker
- Max-Delbrück-Center Berlin (MDC), Robert-Rössle-Str. 10, Berlin 13125, Germany
| | - Marcus Conrad
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany
| | - Martin Hrabě de Angelis
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,German Center for Diabetes Research (DZD e.V.), Neuherberg 85764, Germany.,Technische Universität München, Center of Life and Food Sciences Weihenstephan, Freising 85354, Germany
| | - Bernd Reif
- Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.,Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Germany
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6
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Ott C, Martens H, Hassouna I, Oliveira B, Erck C, Zafeiriou MP, Peteri UK, Hesse D, Gerhart S, Altas B, Kolbow T, Stadler H, Kawabe H, Zimmermann WH, Nave KA, Schulz-Schaeffer W, Jahn O, Ehrenreich H. Erratum to: Widespread Expression of Erythropoietin Receptor in Brain and Its Induction by Injury. Mol Med 2015. [DOI: 10.2119/molmed.2015.00192.erratum] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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7
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Ott C, Martens H, Hassouna I, Oliveira B, Erck C, Zafeiriou MP, Peteri UK, Hesse D, Gerhart S, Altas B, Kolbow T, Stadler H, Kawabe H, Zimmermann WH, Nave KA, Schulz-Schaeffer W, Jahn O, Ehrenreich H. Widespread Expression of Erythropoietin Receptor in Brain and Its Induction by Injury. Mol Med 2015; 21:803-815. [PMID: 26349059 DOI: 10.2119/molmed.2015.00192] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 09/01/2015] [Indexed: 11/06/2022] Open
Abstract
Erythropoietin (EPO) exerts potent neuroprotective, neuroregenerative and procognitive functions. However, unequivocal demonstration of erythropoietin receptor (EPOR) expression in brain cells has remained difficult since previously available anti-EPOR antibodies (EPOR-AB) were unspecific. We report here a new, highly specific, polyclonal rabbit EPOR-AB directed against different epitopes in the cytoplasmic tail of human and murine EPOR and its characterization by mass spectrometric analysis of immuno-precipitated endogenous EPOR, Western blotting, immunostaining and flow cytometry. Among others, we applied genetic strategies including overexpression, Lentivirus-mediated conditional knockout of EpoR and tagged proteins, both on cultured cells and tissue sections, as well as intracortical implantation of EPOR-transduced cells to verify specificity. We show examples of EPOR expression in neurons, oligodendroglia, astrocytes and microglia. Employing this new EPOR-AB with double-labeling strategies, we demonstrate membrane expression of EPOR as well as its localization in intracellular compartments such as the Golgi apparatus. Moreover, we show injury-induced expression of EPOR. In mice, a stereotactically applied stab wound to the motor cortex leads to distinct EpoR expression by reactive GFAP-expressing cells in the lesion vicinity. In a patient suffering from epilepsy, neurons and oligodendrocytes of the hippocampus strongly express EPOR. To conclude, this new analytical tool will allow neuroscientists to pinpoint EPOR expression in cells of the nervous system and to better understand its role in healthy conditions, including brain development, as well as under pathological circumstances, such as upregulation upon distress and injury.
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Affiliation(s)
- Christoph Ott
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | - Imam Hassouna
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Physiology Unit, Zoology Department, Faculty of Science, Menoufia University, Egypt
| | - Bárbara Oliveira
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | | | - Ulla-Kaisa Peteri
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Dörte Hesse
- Proteomics Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Simone Gerhart
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Bekir Altas
- Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | | | - Hiroshi Kawabe
- Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | - Klaus-Armin Nave
- Neurogenetics, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | | | - Olaf Jahn
- Proteomics Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Hannelore Ehrenreich
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
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8
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Stein H, Bob R, Dürkop H, Erck C, Kämpfe D, Kvasnicka HM, Martens H, Roth A, Streubel A. A new monoclonal antibody (CAL2) detects CALRETICULIN mutations in formalin-fixed and paraffin-embedded bone marrow biopsies. Leukemia 2015. [PMID: 26202929 PMCID: PMC4705422 DOI: 10.1038/leu.2015.192] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Recent advances in the diagnostic of myeloproliferative neoplasms (MPNs) discovered CALRETICULIN (CALR) mutations as a major driver in these disorders. In contrast to JAK2 mutations being mainly associated with polycythaemia vera, CALR mutations are only associated with primary myelofibrosis (PMF) and essential thrombocythaemia (ET). CALR mutations are present in the majority of PMF and ET patients lacking JAK2 and MPL mutations. As these CALR mutations are absent from reactive bone marrow (BM) lesions their presence indicates ET or PMF. So far these mutations are detectable only by molecular assays. Their molecular detection is cumbersome because of the great CALR mutation heterogeneity. Therefore, the availability of a simple assay would be of great help. All CALR mutations reported lead to a frameshift generating a new 36 amino-acid C-terminus. We generated a monoclonal antibody (CAL2) to this C-neoterminus by immunizing mice with a representative peptide and compared its performance with Sanger sequencing data in 173 MPNs and other BM diseases. There was a 100% correlation between the molecular and the CAL2 immunohistochemical (IHC) assays. Thus, the detection of CALR mutations by the CAL2 IHC is a specific, sensitive, rapid, simple and low-cost method.
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Affiliation(s)
- H Stein
- Reference and Consultation Center for Lymphoma and Haematopathology, Pathodiagnostik Berlin, Berlin, Germany
| | - R Bob
- Reference and Consultation Center for Lymphoma and Haematopathology, Pathodiagnostik Berlin, Berlin, Germany
| | - H Dürkop
- Reference and Consultation Center for Lymphoma and Haematopathology, Pathodiagnostik Berlin, Berlin, Germany
| | - C Erck
- Synaptic Systems GmbH, Göttingen, Germany
| | - D Kämpfe
- Praxis für Onkologie, Lüdenscheid, Germany
| | - H-M Kvasnicka
- Senckenbergisches Institut für Pathologie, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany
| | - H Martens
- Synaptic Systems GmbH, Göttingen, Germany
| | - A Roth
- Medizinisches Versorgungszentrum am Helios Klinikum Emil von Behring, Labor für molekulare Diagnostik und Mikrobiologie, Berlin, Germany
| | - A Streubel
- Medizinisches Versorgungszentrum am Helios Klinikum Emil von Behring, Labor für molekulare Diagnostik und Mikrobiologie, Berlin, Germany
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9
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Binotti B, Pavlos NJ, Riedel D, Wenzel D, Vorbrüggen G, Schalk AM, Kühnel K, Boyken J, Erck C, Martens H, Chua JJE, Jahn R. The GTPase Rab26 links synaptic vesicles to the autophagy pathway. eLife 2015; 4:e05597. [PMID: 25643395 PMCID: PMC4337689 DOI: 10.7554/elife.05597] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 02/01/2015] [Indexed: 12/27/2022] Open
Abstract
Small GTPases of the Rab family not only regulate target recognition in membrane traffic but also control other cellular functions such as cytoskeletal transport and autophagy. Here we show that Rab26 is specifically associated with clusters of synaptic vesicles in neurites. Overexpression of active but not of GDP-preferring Rab26 enhances vesicle clustering, which is particularly conspicuous for the EGFP-tagged variant, resulting in a massive accumulation of synaptic vesicles in neuronal somata without altering the distribution of other organelles. Both endogenous and induced clusters co-localize with autophagy-related proteins such as Atg16L1, LC3B and Rab33B but not with other organelles. Furthermore, Atg16L1 appears to be a direct effector of Rab26 and binds Rab26 in its GTP-bound form, albeit only with low affinity. We propose that Rab26 selectively directs synaptic and secretory vesicles into preautophagosomal structures, suggesting the presence of a novel pathway for degradation of synaptic vesicles. DOI:http://dx.doi.org/10.7554/eLife.05597.001 Our brain contains billions of cells called neurons that form an extensive network through which information is readily exchanged. These cells connect to each other via junctions called synapses. Our developing brain starts off with far more synapses than it needs, but the excess synapses are destroyed as the brain matures. Even in adults, synapses are continuously made and destroyed in response to experiences and learning. Inside neurons there are tiny bubble-like compartments called vesicles that supply the synapses with many of the proteins and other components that they need. There is a growing body of evidence that suggests these vesicles are rapidly destroyed once a synapse is earmarked for destruction, but it is not clear how this may occur. Here, Binotti, Pavlos et al. found that a protein called Rab26 sits on the surface of the vesicles near synapses. This protein promotes the formation of clusters of vesicles, and a membrane sometimes surrounds these clusters. Further experiments indicate that several proteins involved in a process called autophagy—where unwanted proteins and debris are destroyed—may also be found around the clusters of vesicles. Autophagy starts with the formation of a membrane around the material that needs to be destroyed. This seals the material off from rest of the cell so that enzymes can safely break it down. Binotti, Pavlos et al. found that one of the autophagy proteins—called Atg16L—can bind directly to Rab26, but only when Rab26 is in an ‘active’ state. These findings suggest that excess vesicles at synapses may be destroyed by autophagy. Further work will be required to establish how this process is controlled and how it is involved in the loss of synapses. DOI:http://dx.doi.org/10.7554/eLife.05597.002
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Affiliation(s)
- Beyenech Binotti
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nathan J Pavlos
- School of Surgery, University of Western Australia, Crawley, Australia
| | - Dietmar Riedel
- Facility for Transmission Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dirk Wenzel
- Facility for Transmission Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Gerd Vorbrüggen
- Research Group Molecular Cell Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Amanda M Schalk
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Karin Kühnel
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Janina Boyken
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | | | - John J E Chua
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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10
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Ewald F, Annemann M, Pils MC, Plaza-Sirvent C, Neff F, Erck C, Reinhold D, Schmitz I. Constitutive expression of murine c-FLIPR causes autoimmunity in aged mice. Cell Death Dis 2014; 5:e1168. [PMID: 24722293 PMCID: PMC5424115 DOI: 10.1038/cddis.2014.138] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 02/06/2023]
Abstract
Death receptor-mediated apoptosis is a key mechanism for the control of immune responses and dysregulation of this pathway may lead to autoimmunity. Cellular FLICE-inhibitory proteins (c-FLIPs) are known as inhibitors of death receptor-mediated apoptosis. The only short murine c-FLIP splice variant is c-FLIPRaji (c-FLIPR). To investigate the functional role of c-FLIPR in the immune system, we used the vavFLIPR mouse model constitutively expressing murine c-FLIPR in all hematopoietic compartments. Lymphocytes from these mice are protected against CD95-mediated apoptosis and activation-induced cell death. Young vavFLIPR mice display normal lymphocyte compartments, but the lymphocyte populations alter with age. We identified reduced levels of T cells and slightly higher levels of B cells in 1-year-old vavFLIPR mice compared with wild-type (WT) littermates. Moreover, both B and T cells from aged vavFLIPR animals show activated phenotypes. Sera from 1-year-old WT and transgenic animals were analysed for anti-nuclear antibodies. Notably, elevated titres of these autoantibodies were detected in vavFLIPR sera. Furthermore, tissue damage in kidneys and lungs from aged vavFLIPR animals was observed, indicating that vavFLIPR mice develop a systemic lupus erythematosus-like phenotype with age. Taken together, these data suggest that c-FLIPR is an important modulator of apoptosis and enforced expression leads to autoimmunity.
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Affiliation(s)
- F Ewald
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - M Annemann
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - M C Pils
- Mouse Pathology, Animal Experimental Unit, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - C Plaza-Sirvent
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - F Neff
- Institute of Pathology, Helmholtz Centre Munich, Ingolstaedter Landstr. 1, Neuherberg, Germany
| | - C Erck
- Cellular Proteome Research, Department of Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
| | - D Reinhold
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany
| | - I Schmitz
- 1] Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, Magdeburg, Germany [2] Research Group of Systems-Oriented Immunology and Inflammation Research, Department of Immune Control, Helmholtz Centre for Infection Research, Inhoffenstr. 7, Braunschweig, Germany
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11
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Antonucci F, Alpár A, Kacza J, Caleo M, Verderio C, Giani A, Martens H, Chaudhry FA, Allegra M, Grosche J, Michalski D, Erck C, Hoffmann A, Harkany T, Matteoli M, Härtig W. Cracking down on inhibition: selective removal of GABAergic interneurons from hippocampal networks. J Neurosci 2012; 32:1989-2001. [PMID: 22323713 PMCID: PMC3742881 DOI: 10.1523/jneurosci.2720-11.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 12/07/2011] [Accepted: 12/14/2011] [Indexed: 12/12/2022] Open
Abstract
Inhibitory (GABAergic) interneurons entrain assemblies of excitatory principal neurons to orchestrate information processing in the hippocampus. Disrupting the dynamic recruitment as well as the temporally precise activity of interneurons in hippocampal circuitries can manifest in epileptiform seizures, and impact specific behavioral traits. Despite the importance of GABAergic interneurons during information encoding in the brain, experimental tools to selectively manipulate GABAergic neurotransmission are limited. Here, we report the selective elimination of GABAergic interneurons by a ribosome inactivation approach through delivery of saporin-conjugated anti-vesicular GABA transporter antibodies (SAVAs) in vitro as well as in the mouse and rat hippocampus in vivo. We demonstrate the selective loss of GABAergic--but not glutamatergic--synapses, reduced GABA release, and a shift in excitation/inhibition balance in mixed cultures of hippocampal neurons exposed to SAVAs. We also show the focal and indiscriminate loss of calbindin(+), calretinin(+), parvalbumin/system A transporter 1(+), somatostatin(+), vesicular glutamate transporter 3 (VGLUT3)/cholecystokinin/CB(1) cannabinoid receptor(+) and neuropeptide Y(+) local-circuit interneurons upon SAVA microlesions to the CA1 subfield of the rodent hippocampus, with interneuron debris phagocytosed by infiltrating microglia. SAVA microlesions did not affect VGLUT1(+) excitatory afferents. Yet SAVA-induced rearrangement of the hippocampal circuitry triggered network hyperexcitability associated with the progressive loss of CA1 pyramidal cells and the dispersion of dentate granule cells. Overall, our data identify SAVAs as an effective tool to eliminate GABAergic neurons from neuronal circuits underpinning high-order behaviors and cognition, and whose manipulation can recapitulate pathogenic cascades of epilepsy and other neuropsychiatric illnesses.
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Affiliation(s)
- Flavia Antonucci
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
- Fondazione Filarete, I-20129 Milan, Italy
| | - Alán Alpár
- Division of Molecular Neurobiology, Department of Medical Biochemistry & Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
| | - Johannes Kacza
- Institute of Veterinary Anatomy, University of Leipzig, D-04103 Leipzig, Germany
| | - Matteo Caleo
- CNR Institute of Neuroscience, I-51600 Pisa, Italy
| | - Claudia Verderio
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
| | - Alice Giani
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
| | | | - Farrukh A. Chaudhry
- The Biotechnology Centre of Oslo & Centre for Molecular Biology and Neuroscience, University of Oslo, N-0317 Oslo, Norway
| | | | - Jens Grosche
- Paul Flechsig Institute for Brain Research, University of Leipzig, D-04109 Leipzig, Germany
| | - Dominik Michalski
- Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany
| | | | - Anke Hoffmann
- Institute of Veterinary Anatomy, University of Leipzig, D-04103 Leipzig, Germany
| | - Tibor Harkany
- Division of Molecular Neurobiology, Department of Medical Biochemistry & Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
- European Neuroscience Institute, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom, and
| | - Michela Matteoli
- Department of Medical Pharmacology, CNR Institute of Neuroscience, Università di Milano and
- Instituto Clinico Humanitas, IRCCS, Rozzano, I-20089 Milan, Italy
| | - Wolfgang Härtig
- Paul Flechsig Institute for Brain Research, University of Leipzig, D-04109 Leipzig, Germany
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12
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Kusch K, Hanke K, Holtfreter S, Schmudde M, Kohler C, Erck C, Wehland J, Hecker M, Ohlsen K, Bröker B, Engelmann S. The influence of SaeRS and σB on the expression of superantigens in different Staphylococcus aureus isolates. Int J Med Microbiol 2011; 301:488-99. [DOI: 10.1016/j.ijmm.2011.01.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 01/06/2011] [Accepted: 01/08/2011] [Indexed: 01/10/2023] Open
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13
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Wirths O, Erck C, Martens H, Harmeier A, Geumann C, Jawhar S, Kumar S, Multhaup G, Walter J, Ingelsson M, Degerman-Gunnarsson M, Kalimo H, Huitinga I, Lannfelt L, Bayer TA. Identification of low molecular weight pyroglutamate A{beta} oligomers in Alzheimer disease: a novel tool for therapy and diagnosis. J Biol Chem 2010; 285:41517-24. [PMID: 20971852 PMCID: PMC3009878 DOI: 10.1074/jbc.m110.178707] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/18/2010] [Indexed: 12/19/2022] Open
Abstract
N-terminally truncated Aβ peptides starting with pyroglutamate (AβpE3) represent a major fraction of all Aβ peptides in the brain of Alzheimer disease (AD) patients. AβpE3 has a higher aggregation propensity and stability and shows increased toxicity compared with full-length Aβ. In the present work, we generated a novel monoclonal antibody (9D5) that selectively recognizes oligomeric assemblies of AβpE3 and studied the potential involvement of oligomeric AβpE3 in vivo using transgenic mouse models as well as human brains from sporadic and familial AD cases. 9D5 showed an unusual staining pattern with almost nondetectable plaques in sporadic AD patients and non-demented controls. Interestingly, in sporadic and familial AD cases prominent intraneuronal and blood vessel staining was observed. Using a novel sandwich ELISA significantly decreased levels of oligomers in plasma samples from patients with AD compared with healthy controls were identified. Moreover, passive immunization of 5XFAD mice with 9D5 significantly reduced overall Aβ plaque load and AβpE3 levels, and normalized behavioral deficits. These data indicate that 9D5 is a therapeutically and diagnostically effective monoclonal antibody targeting low molecular weight AβpE3 oligomers.
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Affiliation(s)
- Oliver Wirths
- From the Department of Molecular Psychiatry and Alzheimer, Graduate School, University Medicine Goettingen, 37075 Goettingen, Germany
| | | | | | - Anja Harmeier
- the Institute of Chemistry and Biochemistry, Free University of Berlin, 14195 Berlin, Germany
| | | | - Sadim Jawhar
- From the Department of Molecular Psychiatry and Alzheimer, Graduate School, University Medicine Goettingen, 37075 Goettingen, Germany
| | - Sathish Kumar
- the Department of Neurology, Molecular Cell Biology, University of Bonn, 53127 Bonn, Germany
| | - Gerd Multhaup
- the Institute of Chemistry and Biochemistry, Free University of Berlin, 14195 Berlin, Germany
| | - Jochen Walter
- the Department of Neurology, Molecular Cell Biology, University of Bonn, 53127 Bonn, Germany
| | - Martin Ingelsson
- the Department of Public Health and Caring Sciences Rudbeck Laboratory, Uppsala University, SE 75185 Uppsala, Sweden
| | - Malin Degerman-Gunnarsson
- the Department of Public Health and Caring Sciences Rudbeck Laboratory, Uppsala University, SE 75185 Uppsala, Sweden
| | - Hannu Kalimo
- the Department of Pathology, University of Helsinki, FI-00014 Helsingin yliopisto, Finland, and
| | - Inge Huitinga
- the Netherlands Brain Bank, Netherlands Institute for Neuroscience, 1105 BA Amsterdam, Netherlands
| | - Lars Lannfelt
- the Department of Public Health and Caring Sciences Rudbeck Laboratory, Uppsala University, SE 75185 Uppsala, Sweden
| | - Thomas A. Bayer
- From the Department of Molecular Psychiatry and Alzheimer, Graduate School, University Medicine Goettingen, 37075 Goettingen, Germany
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14
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Hahn P, Wegener I, Burrells A, Böse J, Wolf A, Erck C, Butler D, Schofield CJ, Böttger A, Lengeling A. Analysis of Jmjd6 cellular localization and testing for its involvement in histone demethylation. PLoS One 2010; 5:e13769. [PMID: 21060799 PMCID: PMC2966431 DOI: 10.1371/journal.pone.0013769] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 10/05/2010] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Methylation of residues in histone tails is part of a network that regulates gene expression. JmjC domain containing proteins catalyze the oxidative removal of methyl groups on histone lysine residues. Here, we report studies to test the involvement of Jumonji domain-containing protein 6 (Jmjd6) in histone lysine demethylation. Jmjd6 has recently been shown to hydroxylate RNA splicing factors and is known to be essential for the differentiation of multiple tissues and cells during embryogenesis. However, there have been conflicting reports as to whether Jmjd6 is a histone-modifying enzyme. METHODOLOGY/PRINCIPAL FINDINGS Immunolocalization studies reveal that Jmjd6 is distributed throughout the nucleoplasm outside of regions containing heterochromatic DNA, with occasional localization in nucleoli. During mitosis, Jmjd6 is excluded from the nucleus and reappears in the telophase of the cell cycle. Western blot analyses confirmed that Jmjd6 forms homo-multimers of different molecular weights in the nucleus and cytoplasm. A comparison of mono-, di-, and tri-methylation states of H3K4, H3K9, H3K27, H3K36, and H4K20 histone residues in wildtype and Jmjd6-knockout cells indicate that Jmjd6 is not involved in the demethylation of these histone lysine residues. This is further supported by overexpression of enzymatically active and inactive forms of Jmjd6 and subsequent analysis of histone methylation patterns by immunocytochemistry and western blot analysis. Finally, treatment of cells with RNase A and DNase I indicate that Jmjd6 may preferentially associate with RNA/RNA complexes and less likely with chromatin. CONCLUSIONS/SIGNIFICANCE Taken together, our results provide further evidence that Jmjd6 is unlikely to be involved in histone lysine demethylation. We confirmed that Jmjd6 forms multimers and showed that nuclear localization of the protein involves association with a nucleic acid matrix.
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Affiliation(s)
- Phillip Hahn
- Department of Experimental Mouse Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Ivonne Wegener
- Department of Experimental Mouse Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Alison Burrells
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, United Kingdom
| | - Jens Böse
- Department of Experimental Mouse Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Alexander Wolf
- Department of Biology II, Ludwig-Maximilians-University, Planeeg-Martinsried, Germany
| | | | - Danica Butler
- Chemistry Research Laboratory and the Oxford Centre for Integrative Systems Biology, University of Oxford, Oxford, United Kingdom
| | - Christopher J. Schofield
- Chemistry Research Laboratory and the Oxford Centre for Integrative Systems Biology, University of Oxford, Oxford, United Kingdom
| | - Angelika Böttger
- Department of Biology II, Ludwig-Maximilians-University, Planeeg-Martinsried, Germany
| | - Andreas Lengeling
- Department of Experimental Mouse Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, United Kingdom
- * E-mail:
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15
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Quiel A, Jürgen B, Piechotta G, Le Foll AP, Ziebandt AK, Kohler C, Köster D, Engelmann S, Erck C, Hintsche R, Wehland J, Hecker M, Schweder T. Electrical protein array chips for the detection of staphylococcal virulence factors. Appl Microbiol Biotechnol 2009; 85:1619-27. [DOI: 10.1007/s00253-009-2347-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 11/05/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
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16
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Probst-Kepper M, Geffers R, Kröger A, Viegas N, Erck C, Hecht HJ, Lünsdorf H, Roubin R, Moharregh-Khiabani D, Wagner K, Ocklenburg F, Jeron A, Garritsen H, Arstila TP, Kekäläinen E, Balling R, Hauser H, Buer J, Weiss S. GARP: a key receptor controlling FOXP3 in human regulatory T cells. J Cell Mol Med 2009; 13:3343-57. [PMID: 19453521 PMCID: PMC4516490 DOI: 10.1111/j.1582-4934.2009.00782.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 04/03/2009] [Indexed: 11/30/2022] Open
Abstract
Recent evidence suggests that regulatory pathways might control sustained high levels of FOXP3 in regulatory CD4(+)CD25(hi) T (T(reg)) cells. Based on transcriptional profiling of ex vivo activated T(reg) and helper CD4(+)CD25(-) T (T(h)) cells we have identified GARP (glycoprotein-A repetitions predominant), LGALS3 (lectin, galactoside-binding, soluble, 3) and LGMN (legumain) as novel genes implicated in human T(reg) cell function, which are induced upon T-cell receptor stimulation. Retroviral overexpression of GARP in antigen-specific T(h) cells leads to an efficient and stable re-programming of an effector T cell towards a regulatory T cell, which involves up-regulation of FOXP3, LGALS3, LGMN and other T(reg)-associated markers. In contrast, overexpression of LGALS3 and LGMN enhance FOXP3 and GARP expression, but only partially induced a regulatory phenotype. Lentiviral down-regulation of GARP in T(reg) cells significantly impaired the suppressor function and was associated with down-regulation of FOXP3. Moreover, down-regulation of FOXP3 resulted in similar phenotypic changes and down-regulation of GARP. This provides compelling evidence for a GARP-FOXP3 positive feedback loop and provides a rational molecular basis for the known difference between natural and transforming growth factor-beta induced T(reg) cells as we show here that the latter do not up-regulate GARP. In summary, we have identified GARP as a key receptor controlling FOXP3 in T(reg) cells following T-cell activation in a positive feedback loop assisted by LGALS3 and LGMN, which represents a promising new system for the therapeutic manipulation of T cells in human disease.
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Affiliation(s)
- M Probst-Kepper
- Junior Research Group for Xenotransplantation, Department of Visceral and Transplant Surgery, Hannover Medical SchoolHannover, Germany
| | - R Geffers
- Mucosal Immunity Research Group, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - A Kröger
- Department of Molecular Biotechnology, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - N Viegas
- Department of Molecular Immunology, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - C Erck
- Synaptic Systems GmbHGoettingen, Germany
| | - H-J Hecht
- Department of Structural Biology, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - H Lünsdorf
- Department of Environmental Microbiology, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - R Roubin
- Institut de Cancerologie de MarseilleMarseille, France
| | - D Moharregh-Khiabani
- Junior Research Group for Xenotransplantation, Department of Visceral and Transplant Surgery, Hannover Medical SchoolHannover, Germany
| | - K Wagner
- Junior Research Group for Xenotransplantation, Department of Visceral and Transplant Surgery, Hannover Medical SchoolHannover, Germany
| | - F Ocklenburg
- Junior Research Group for Xenotransplantation, Department of Visceral and Transplant Surgery, Hannover Medical SchoolHannover, Germany
| | - A Jeron
- Mucosal Immunity Research Group, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - H Garritsen
- Institute for Clinical Transfusion Medicine, Städtisches Klinikum Braunschweig gGmbHBraunschweig, Germany
| | - TP Arstila
- Haartman Institute, Department of Immunology, University of HelsinkiHaartmaninkatu, Finland
| | - E Kekäläinen
- Haartman Institute, Department of Immunology, University of HelsinkiHaartmaninkatu, Finland
| | - R Balling
- Biological Systems Analysis, Helmholtz Centre for Infection ResearchInhoffenstraße, Braunschweig, Germany
| | - H Hauser
- Department of Molecular Biotechnology, Helmholtz Centre for Infection ResearchBraunschweig, Germany
| | - J Buer
- Institute for Medical Microbiology, University EssenEssen, Germany
| | - S Weiss
- Department of Molecular Immunology, Helmholtz Centre for Infection ResearchBraunschweig, Germany
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17
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Meissner A, Wild V, Simm R, Rohde M, Erck C, Bredenbruch F, Morr M, Römling U, Häussler S. Pseudomonas aeruginosa cupA-encoded fimbriae expression is regulated by a GGDEF and EAL domain-dependent modulation of the intracellular level of cyclic diguanylate. Environ Microbiol 2008; 9:2475-85. [PMID: 17803773 DOI: 10.1111/j.1462-2920.2007.01366.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cyclic-diguanylate (c-di-GMP) is a widespread bacterial signal molecule that plays a major role in the modulation of cellular surface components, such as exopolysaccharides and fimbriae, and in the establishment of a sessile life style. Here, we report that intracellular c-di-GMP levels influence cupA-encoded fimbriae expression in Pseudomonas aeruginosa. In an autoaggregative P. aeruginosa small colony variant (SCV) CupA fimbriae and the intracellular c-di-GMP concentration were found to be enhanced as compared with the clonal wild-type. The SCV morphology and the expression of CupA fimbriae were dependent on a functional PA1120 and morA gene both encoding a GGDEF domain. Overexpression of the GGDEF domain protein PA1120 complemented the PA1120 and the morA mutant with respect to CupA fimbriae expression. In agreement with these findings, overexpression of the EAL domain containing phenotypic variance regulator (PvrR) in the SCV resulted in a decreased intracellular level of c-di-GMP, a reduced cupA fimbriae expression and a switch to wild-type colony morphology.
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Affiliation(s)
- Andree Meissner
- Division of Cell Biology and Immunology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
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18
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Erck C, Peris L, Andrieux A, Meissirel C, Gruber AD, Vernet M, Schweitzer A, Saoudi Y, Pointu H, Bosc C, Salin PA, Job D, Wehland J. A vital role of tubulin-tyrosine-ligase for neuronal organization. Proc Natl Acad Sci U S A 2005; 102:7853-8. [PMID: 15899979 PMCID: PMC1129054 DOI: 10.1073/pnas.0409626102] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tubulin is subject to a special cycle of detyrosination/tyrosination in which the C-terminal tyrosine of alpha-tubulin is cyclically removed by a carboxypeptidase and readded by a tubulin-tyrosine-ligase (TTL). This tyrosination cycle is conserved in evolution, yet its physiological importance is unknown. Here, we find that TTL suppression in mice causes perinatal death. A minor pool of tyrosinated (Tyr-)tubulin persists in TTL null tissues, being present mainly in dividing TTL null cells where it originates from tubulin synthesis, but it is lacking in postmitotic TTL null cells such as neurons, which is apparently deleterious because early death in TTL null mice is, at least in part, accounted for by a disorganization of neuronal networks, including a disruption of the cortico-thalamic loop. Correlatively, cultured TTL null neurons display morphogenetic anomalies including an accelerated and erratic time course of neurite outgrowth and a premature axonal differentiation. These anomalies may involve a mislocalization of CLIP170, which we find lacking in neurite extensions and growth cones of TTL null neurons. Our results demonstrate a vital role of TTL for neuronal organization and suggest a requirement of Tyr-tubulin for proper control of neurite extensions.
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Affiliation(s)
- Christian Erck
- Department of Cell Biology, German Research Center for Biotechnology, D-38124 Braunschweig, Germany
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Erck C, MacLeod RAF, Wehland J. Cloning and genomic organization of the TTL gene on mouse chromosome 2 and human chromosome 2q13. Cytogenet Genome Res 2004; 101:47-53. [PMID: 14571137 DOI: 10.1159/000073418] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2002] [Accepted: 04/09/2003] [Indexed: 11/19/2022] Open
Abstract
Tubulin tyrosine ligase (TTL) is a cytosolic enzyme involved in the posttranslational modification of tubulin. In the assembled form microtubules are detyrosinated over time at the C-terminus of alpha-tubulin. After microtubular disassembly TTL restores tyrosine residues back to the detyrosinated tubulin leading to a cycle of detyrosination/tyrosination. Here we report the isolation of the human and mouse TTL cDNA. In comparison with other known TTL sequences, namely bovine, rat and porcine, we found that only porcine TTL deviates in length by having an insertion of two glutamate residues. In mouse and human TTL the genomic coding sequence is composed of seven exons with normal intron/exon boundaries. Using fluorescence in situ hybridization (FISH), we mapped the murine TTL gene to mouse chromosome 2 (MMU2). Human TTL has been located to chromosome 2q13 (HSA2q13). In addition, we found frequently truncated PCR products of hTTL transcripts with aberrant splicing in tumors.
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MESH Headings
- 5' Flanking Region/genetics
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- Cell Line, Tumor
- Chromosome Mapping
- Chromosomes, Human, Pair 2/genetics
- Chromosomes, Mammalian/genetics
- Cloning, Molecular
- DNA/chemistry
- DNA/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Exons
- Genes/genetics
- HeLa Cells
- Humans
- In Situ Hybridization, Fluorescence
- Introns
- Mice
- Mice, Inbred Strains
- Molecular Sequence Data
- NIH 3T3 Cells
- Peptide Synthases/genetics
- Phylogeny
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- C Erck
- Department of Cell Biology, German Research Center of Biotechnology, Braunschweig, Germany.
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Kalisz HM, Erck C, Plessmann U, Wehland J. Incorporation of nitrotyrosine into alpha-tubulin by recombinant mammalian tubulin-tyrosine ligase. Biochim Biophys Acta 2000; 1481:131-8. [PMID: 11004583 DOI: 10.1016/s0167-4838(00)00110-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Tubulin-tyrosine ligase (TTL, EC 6.3.2.25) from porcine brain, which catalyses the readdition of tyrosine to the C-terminus of detyrosinated alpha-tubulin, was cloned and expressed in Escherichia coli as a glutathione S-transferase-fusion protein. Upon cleavage of the immobilised fusion protein, an electrophoretically homogeneous enzyme was obtained. Recombinant TTL, which exhibited similar catalytic properties as the mammalian enzyme purified from brain tissue, was capable of using nitrotyrosine as an alternative substrate in vitro. Incorporation of tyrosine into tubulin was competitively inhibited by nitrotyrosine with an apparent K(i) of 0.24 mM. The TTL-catalysed incorporation of nitrotyrosine as sole substrate into alpha-tubulin was clearly detectable at concentrations of 10 microM by immunological methods using nitrotyrosine specific antibodies. However, in competition with tyrosine 20-fold higher concentrations of nitrotyrosine were necessary before its incorporation became evident. Analysis of the C-terminal peptides of in vitro modified alpha-tubulin by MALDI-MS confirmed the covalent incorporation of nitrotyrosine into tubulin by TTL. In contrast to the C-terminal tyrosine, pancreatic carboxypeptidase A was incapable of cleaving nitrotyrosine from the modified alpha-tubulin.
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Affiliation(s)
- H M Kalisz
- Gesellschaft für Biotechnologische Forschung, Abteilung Zellbiologie, Braunschweig, Germany
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Abstract
Tubulins and microtubules are subjected to several post-translational modifications of which the reversible detyrosination/tyrosination of the carboxy-terminal end of most alpha-tubulins has been extensively analysed. This modification cycle involves a specific carboxypeptidase and the activity of the tubulin-tyrosine ligase (TTL). The true physiological function of TTL has so far not been established. This review describes the purification of TTL to homogeneity by biochemical methods, its in vitro properties and the generation of monoclonal antibodies. These mabs not only enabled a very convenient and rapid purification of TTL by immunoaffinity chromatography but also its extensive characterization by protein sequencing, which led to the isolation of the full length cDNA. With this information, gene disruption should be feasible in order to determine the physiological significance of the tyrosination cycle.
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Affiliation(s)
- C Erck
- Abteilung Zellbiologie, Gesellschaft fuer Biotechnologische Forschung, Braunschweig, Germany
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Abstract
In our preceding report, we have shown that nerve growth factor (NGF) and its low-affinity receptor (p75NTR) are expressed in C2C12 myoblasts and downregulated during myogenic differentiation. Furthermore, NGF affects myogenic differentiation and cell growth via p75NTR and downregulation of p75NTR is essential for myogenic differentiation (Seidl et al., 1998). Here we show that NGF and p75NTR are regulated by mechanisms preceding terminal differentiation in myogenic cells. These mechanisms include cell-density phenomena such as cell-cell contact as well as signaling of basic fibroblast growth factor (FGF-2) and its receptor (FGFR1). Downregulation of NGF and p75NTR occurred as a consequence of increasing cell density, an important trigger for the onset of myogenic differentiation. FGF-2 and FGFR1 were shown to be present in C2C12 cells and exogenous FGF-2 induced NGF and p75NTR expression, implying that FGF/FGFR signaling is an upstream regulator of the NGF/p75NTR system. The fact that FGF-2 could suspend yet not abolish density-induced downregulation indicates that cell-cell contact counteracts the FGF effect and ultimately terminates NGF/p75NTR signaling. This evidence, together with the observation that p75NTR expression is suppressed in muscle progenitors, which constitutively express adenovirus E1A proteins and thus lack the competence of myogenic differentiation, underline the important role for the NGF/p75NTR system in the interplay of multiple factors and biological systems that balance myogenic differentiation at the appropriate spatial and temporal level.
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Affiliation(s)
- C Erck
- Department of Cell and Molecular Biology, Institute for Biochemistry and Biotechnology, University of Braunschweig, Germany
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Abstract
We have studied expression and function of neurotrophins and their receptors during myogenic differentiation of C2C12 cells, a clonal cell line derived from mouse muscle that is capable of in vitro differentiation. The genes coding for nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and their common low-affinity receptor p75(neurotrophin receptor) (p75NTR) were shown to be expressed in C2C12 myoblasts and downregulated during myogenic differentiation and fusion into myotubes. Cocultures with dorsal root ganglia from day 8 chick embryos revealed neurite-promoting activities of C2C12 cells that ceased with myogenic differentiation. These data suggest a temporal and developmental window for the effect of myogenic cell-derived neurotrophins on neuronal as well as on myogenic cell populations. NGF was shown to increase DNA synthesis and cell growth of C2C12 myoblasts and to enhance myogenic differentiation in this cell line. We present evidence that NGF-mediated processes take place at stages preceding myogenic differentiation. Enhanced muscle differentiation was also seen in p75NTR-overexpressing C2C12 myoblasts which maintained high levels of receptors but ceased to produce NGF during differentiation. In contrast, when exogenous NGF was present at the onset of myogenic differentiation of receptor-overexpressing cells, muscle cell development was strongly repressed. This indicates that downregulation of p75NTR is necessary for guiding myogenic cells towards terminal differentiation. Since none of the trk high-affinity neurotrophin receptors could be demonstrated in C2C12 cells, we conclude that NGF mediates its nonneurotrophic effect via its low-affinity receptor in an autocrine fashion.
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Affiliation(s)
- K Seidl
- Institute for Biochemistry and Biotechnology, Department of Cell and Molecular Biology, University of Braunschweig, Germany.
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Abstract
In an effort to clarify transient expression of the NGF low-affinity receptor p75NGFR during muscle development we have focused on the molecular mechanisms involved in the initiation and cessation of p75NGFR gene expression. Using quiescent C3H10T1/2 fibroblast as a tool, we observed that induction of differentiation competence in MyoD-transfected 10T1/2 fibroblasts was accompanied by the initiation of p75NGFR expression. Moreover, we could show that the bHLH transcription factor MyoD itself is a powerful candidate for transcriptional activation of the p75NGFR gene in muscle precursor cells. By means of MyoD-mutants we have found that both the amino terminus of the MyoD molecule as well as the bHLH-region are essential for transcriptional activity on the p75NGFR promoter. The fact that myocyte enhancer factor MEF2A inactivated MyoD-induced p75NGFR promoter activity strongly suggests that cell-specific regulation of the p75NGFR gene might be strictly dependent on the intracellular composition and balance of the appropriate bHLH-transcription factors and their modulators.
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Affiliation(s)
- C Erck
- Department of Cell and Molecular Biology, University of Braunschweig, FRG
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Seidl K, Buchberger A, Erck C. Expression of nerve growth factor and neurotrophin receptors in testicular cells suggest novel roles for neurotrophins outside the nervous system. Reprod Fertil Dev 1996; 8:1075-87. [PMID: 8916284 DOI: 10.1071/rd9961075] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The present study was designed to clarify the non-neurotrophic role for neurotrophins in mouse testis. By means of SI nuclease protection assay we could demonstrate that the gene coding for the low-affinity nerve growth factor (NGF) receptor p75NGFR is transiently expressed during germ cell development. Gene expression for p75NGFR was detected in late-meiotic spermatocytes and early spermatids and was found to be co-expressed with trkB and trkC, two tyrosine kinase receptors, commonly regarded as the high-affinity receptors for brain-derived neurotrophic factor and neurotrophin-3. Gene transcripts for the high-affinity NGF receptor trkA were found exclusively in non-germ cells. Isolated Leydig cells, peritubular myoid cells and Sertoli cells, but not germ cells, could be identified as potential testicular NGF sources. Non-germ cells respond after incubation for several days with a sharp induction in NGF synthesis, which is accompanied by a loss of phenotypic expression patterns. The fact that p75NGFR mRNA expression was induced in cultured Sertoli cells and peritubular myoid cells suggests an autocrine mode of NGF action in these cells. Induction of NGF synthesis in cultured Leydig cells could be prevented by the glucocorticoid dexamethasone. Results indicate different roles for the individual neurotrophins in distinct testicular compartments and suggest that these neurotrophins might support testicular functions by signalling between individual cell types in an autocrine and paracrine manner.
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Affiliation(s)
- K Seidl
- Department of Cell and Molecular Biology, University of Braunschweig, FRG
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