1
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Burkart V, Kowalski K, Disch A, Hilfiker-Kleiner D, Lal S, Dos Remedios C, Perrot A, Zeug A, Ponimaskin E, Kosanke M, Dittrich-Breiholz O, Kraft T, Montag J. Nonsense mediated decay factor UPF3B is associated with cMyBP-C haploinsufficiency in hypertrophic cardiomyopathy patients. J Mol Cell Cardiol 2023; 185:26-37. [PMID: 37797718 DOI: 10.1016/j.yjmcc.2023.09.008] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 09/08/2023] [Accepted: 09/28/2023] [Indexed: 10/07/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiac disease. Up to 40% of cases are associated with heterozygous mutations in myosin binding protein C (cMyBP-C, MYBPC3). Most of these mutations lead to premature termination codons (PTC) and patients show reduction of functional cMyBP-C. This so-called haploinsufficiency most likely contributes to disease development. We analyzed mechanisms underlying haploinsufficiency using cardiac tissue from HCM-patients with truncation mutations in MYBPC3 (MYBPC3trunc). We compared transcriptional activity, mRNA and protein expression to donor controls. To differentiate between HCM-specific and general hypertrophy-induced mechanisms we used patients with left ventricular hypertrophy due to aortic stenosis (AS) as an additional control. We show that cMyBP-C haploinsufficiency starts at the mRNA level, despite hypertrophy-induced increased transcriptional activity. Gene set enrichment analysis (GSEA) of RNA-sequencing data revealed an increased expression of NMD-components. Among them, Up-frameshift protein UPF3B, a regulator of NMD was upregulated in MYBPC3trunc patients and not in AS-patients. Strikingly, we show that in sarcomeres UPF3B but not UPF1 and UPF2 are localized to the Z-discs, the presumed location of sarcomeric protein translation. Our data suggest that cMyBP-C haploinsufficiency in HCM-patients is established by UPF3B-dependent NMD during the initial translation round at the Z-disc.
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Affiliation(s)
- Valentin Burkart
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany.
| | - Kathrin Kowalski
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Alina Disch
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | | | - Sean Lal
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Cristobal Dos Remedios
- Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Andreas Perrot
- Charité - Universitätsmedizin Berlin, Experimental & Clinical Research Center, Berlin, Germany
| | - Andre Zeug
- Institute of Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Evgeni Ponimaskin
- Institute of Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Maike Kosanke
- Research Core Unit Genomics, Hannover Medical School, Hannover, Germany
| | | | - Theresia Kraft
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Judith Montag
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
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2
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Wunderlich S, Haase A, Merkert S, Jahn K, Deest M, Frieling H, Glage S, Korte W, Martens A, Kirschning A, Zeug A, Ponimaskin E, Göhring G, Ackermann M, Lachmann N, Moritz T, Zweigerdt R, Martin U. Targeted biallelic integration of an inducible Caspase 9 suicide gene in iPSCs for safer therapies. Mol Ther Methods Clin Dev 2022; 26:84-94. [PMID: 35795779 PMCID: PMC9234009 DOI: 10.1016/j.omtm.2022.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/25/2022] [Indexed: 11/16/2022]
Abstract
Drug-inducible suicide systems may help to minimize risks of human induced pluripotent stem cell (hiPSC) therapies. Recent research challenged the usefulness of such systems since rare drug-resistant subclones were observed. We have introduced a drug-inducible Caspase 9 suicide system (iCASP9) into the AAVS1 safe-harbor locus of hiPSCs. In these cells, apoptosis could be efficiently induced in vitro. After transplantation into mice, drug treatment generally led to rapid elimination of teratomas, but single animals subsequently formed tumor tissue from monoallelic iCASP9 hiPSCs. Very rare drug-resistant subclones of monoallelic iCASP9 hiPSCs appeared in vitro with frequencies of ∼ 3 × 10-8. Besides transgene elimination, presumably via loss of heterozygosity (LoH), silencing via aberrant promoter methylation was identified as a major underlying mechanism. In contrast to monoallelic iCASP9 hiPSCs, no escapees from biallelic iCASP9 cells were observed after treatment of up to 0.8 billion hiPSCs. The highly increased safety level provided by biallelic integration of the iCASP9 system may substantially contribute to the safety level of iPSC-based therapies.
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Affiliation(s)
- Stephanie Wunderlich
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany
| | - Alexandra Haase
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany
| | - Sylvia Merkert
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany
| | - Kirsten Jahn
- Laboratory for Molecular Neuroscience, Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, 30625 Hannover, Germany
| | - Maximillian Deest
- Laboratory for Molecular Neuroscience, Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, 30625 Hannover, Germany
| | - Helge Frieling
- Laboratory for Molecular Neuroscience, Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, 30625 Hannover, Germany
| | - Silke Glage
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Institute for Laboratory Animal Science, Hannover Medical School, 30625 Hannover, Germany
| | - Wilhelm Korte
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany
| | - Andreas Martens
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany
| | - Andreas Kirschning
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Institute for Organic Chemistry, Leibniz University Hannover, 30167 Hannover, Germany
| | - Andre Zeug
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Department of Cellular Neurophysiology; Hannover Medical School, 30625 Hannover, Germany
| | - Evgeni Ponimaskin
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Department of Cellular Neurophysiology; Hannover Medical School, 30625 Hannover, Germany
| | - Gudrun Göhring
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Department of Human Genetics, Hannover Medical School, 30625 Hannover, Germany
| | - Mania Ackermann
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany.,Institute of Experimental Hematology, Hannover Medical School, 30625 Hannover, Germany
| | - Nico Lachmann
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany.,Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany.,Institute of Experimental Hematology, Hannover Medical School, 30625 Hannover, Germany.,Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, 30625 Hannover, Germany
| | - Thomas Moritz
- REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,RG Reprogramming and Gene Therapy, Hannover Medical School, 30625 Hannover, Germany.,Institute of Experimental Hematology, Hannover Medical School, 30625 Hannover, Germany
| | - Robert Zweigerdt
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany
| | - Ulrich Martin
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany.,REBIRTH - Research Center for Translational Regenerative Medicine, 30625 Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany
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3
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Burkart V, Kowalski K, Aldag-Niebling D, Beck J, Frick DA, Holler T, Radocaj A, Piep B, Zeug A, Hilfiker-Kleiner D, dos Remedios CG, van der Velden J, Montag J, Kraft T. Transcriptional bursts and heterogeneity among cardiomyocytes in hypertrophic cardiomyopathy. Front Cardiovasc Med 2022; 9:987889. [PMID: 36082122 PMCID: PMC9445301 DOI: 10.3389/fcvm.2022.987889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/02/2022] [Indexed: 12/01/2022] Open
Abstract
Transcriptional bursting is a common expression mode for most genes where independent transcription of alleles leads to different ratios of allelic mRNA from cell to cell. Here we investigated burst-like transcription and its consequences in cardiac tissue from Hypertrophic Cardiomyopathy (HCM) patients with heterozygous mutations in the sarcomeric proteins cardiac myosin binding protein C (cMyBP-C, MYBPC3) and cardiac troponin I (cTnI, TNNI3). Using fluorescence in situ hybridization (RNA-FISH) we found that both, MYBPC3 and TNNI3 are transcribed burst-like. Along with that, we show unequal allelic ratios of TNNI3-mRNA among single cardiomyocytes and unequally distributed wildtype cMyBP-C protein across tissue sections from heterozygous HCM-patients. The mutations led to opposing functional alterations, namely increasing (cMyBP-Cc.927−2A>G) or decreasing (cTnIR145W) calcium sensitivity. Regardless, all patients revealed highly variable calcium-dependent force generation between individual cardiomyocytes, indicating contractile imbalance, which appears widespread in HCM-patients. Altogether, we provide strong evidence that burst-like transcription of sarcomeric genes can lead to an allelic mosaic among neighboring cardiomyocytes at mRNA and protein level. In HCM-patients, this presumably induces the observed contractile imbalance among individual cardiomyocytes and promotes HCM-development.
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Affiliation(s)
- Valentin Burkart
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
- Valentin Burkart
| | - Kathrin Kowalski
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - David Aldag-Niebling
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Julia Beck
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Dirk Alexander Frick
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Tim Holler
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Ante Radocaj
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Birgit Piep
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
| | - Andre Zeug
- Institute for Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | | | - Cristobal G. dos Remedios
- Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | | | - Judith Montag
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
- *Correspondence: Judith Montag
| | - Theresia Kraft
- Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany
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4
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Roig SR, Cassinelli S, Zeug A, Ponimaskin E, Felipe A. Oligomerization and Spatial Distribution of Kvβ1.1 and Kvβ2.1 Regulatory Subunits. Front Physiol 2022; 13:930769. [PMID: 35784882 PMCID: PMC9247503 DOI: 10.3389/fphys.2022.930769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/02/2022] [Indexed: 11/13/2022] Open
Abstract
Members of the regulatory Kvβ family modulate the kinetics and traffic of voltage-dependent K+ (Kv) channels. The crystal structure of Kv channels associated with Kvβ peptides suggests a α4/β4 composition. Although Kvβ2 and Kvβ1 form heteromers, evidence supports that only Kvβ2.1 forms tetramers in the absence of α subunits. Therefore, the stoichiometry of the Kvβ oligomers fine-tunes the activity of hetero-oligomeric Kv channel complexes. We demonstrate that Kvβ subtypes form homo- and heterotetramers with similar affinities. The Kvβ1.1/Kvβ2.1 heteromer showed an altered spatial distribution in lipid rafts, recapitulating the Kvβ1.1 pattern. Because Kvβ2 is an active partner of the Kv1.3-TCR complex at the immunological synapse (IS), an association with Kvβ1 would alter this location, shaping the immune response. Differential regulation of Kvβs influences the traffic and architecture of the Kvβ heterotetramer, modulating Kvβ-dependent physiological responses.
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Affiliation(s)
- Sara R. Roig
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
- Imaging Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
- *Correspondence: Antonio Felipe,
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5
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Müller FE, Cherkas V, Stopper G, Caudal LC, Stopper L, Kirchhoff F, Henneberger C, Ponimaskin EG, Zeug A. Elucidating regulators of astrocytic Ca 2+ signaling via multi-threshold event detection (MTED). Glia 2021; 69:2798-2811. [PMID: 34388285 DOI: 10.1002/glia.24070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 01/23/2023]
Abstract
Recent achievements in indicator optimization and imaging techniques promote the advancement of functional imaging to decipher complex signaling processes in living cells, such as Ca2+ activity patterns. Astrocytes are important regulators of the brain network and well known for their highly complex morphology and spontaneous Ca2+ activity. However, the astrocyte community is lacking standardized methods to analyze and interpret Ca2+ activity recordings, hindering global comparisons. Here, we present a biophysically-based analytical concept for deciphering the complex spatio-temporal changes of Ca2+ biosensor fluorescence for understanding the underlying signaling mechanisms. We developed a pixel-based multi-threshold event detection (MTED) analysis of multidimensional data, which accounts for signal strength as an additional signaling dimension and provides the experimenter with a comprehensive toolbox for a differentiated and in-depth characterization of fluorescence signals. MTED was validated by analyzing astrocytic Ca2+ activity across Ca2+ indicators, imaging setups, and model systems from primary cell culture to awake, head-fixed mice. We identified extended Ca2+ activity at 25°C compared to 37°C physiological body temperature and dissected how neuronal activity shapes long-lasting astrocytic Ca2+ activity. Our MTED strategy, as a parameter-free approach, is easily transferrable to other fluorescent indicators and biosensors and embraces the additional dimensionality of signaling activity strength. It will also advance the definition of standardized procedures and parameters to improve comparability of research data and reports.
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Affiliation(s)
| | - Volodymyr Cherkas
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Gebhard Stopper
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Laura C Caudal
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Laura Stopper
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Institute of Neurology, University College London, London, UK
| | | | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
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6
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Lacivita E, Niso M, Mastromarino M, Garcia Silva A, Resch C, Zeug A, Loza MI, Castro M, Ponimaskin E, Leopoldo M. Knowledge-Based Design of Long-Chain Arylpiperazine Derivatives Targeting Multiple Serotonin Receptors as Potential Candidates for Treatment of Autism Spectrum Disorder. ACS Chem Neurosci 2021; 12:1313-1327. [PMID: 33792287 DOI: 10.1021/acschemneuro.0c00647] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Autism spectrum disorder (ASD) includes a group of neurodevelopmental disorders characterized by core symptoms such as impaired social interaction and communication, repetitive and stereotyped behaviors, and restricted interests. To date, there are no effective treatments for these core symptoms. Several studies have shown that the brain serotonin (5-HT) neurotransmission system is altered in both ASD patients and animal models of the disease. Multiple pieces of evidence suggest that targeting 5-HT receptors may treat the core symptoms of ASD and associated intellectual disabilities. In fact, stimulation of the 5-HT1A receptor reduces repetitive and restricted behaviors; blockade of the 5-HT2A receptor reduces both learning deficits and repetitive behavior, and activation of the 5-HT7 receptor improves cognitive performances and reduces repetitive behavior. On such a basis, we have designed novel arylpiperazine derivatives pursuing unprecedently reported activity profiles: dual 5-HT7/5-HT1A receptor agonist properties and mixed 5-HT7 agonist/5-HT1A agonist/5-HT2A antagonist properties. Seventeen new compounds were synthesized and tested in radioligand binding assay at the target receptors. We have identified the dual 5-HT1AR/5-HT7R agonists 8c and 29 and the mixed 5-HT1AR agonist/5-HT7R agonist/5-HT2AR antagonist 20b. These compounds are metabolically stable in vitro and have suitable central nervous system druglike properties.
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Affiliation(s)
- Enza Lacivita
- Dipartimento di Farmacia−Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona, 4, 70125 Bari, Italy
| | - Mauro Niso
- Dipartimento di Farmacia−Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona, 4, 70125 Bari, Italy
| | - Margherita Mastromarino
- Dipartimento di Farmacia−Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona, 4, 70125 Bari, Italy
| | - Andrea Garcia Silva
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS). Universidade de Santiago de Compostela. Avda. de Barcelona, s/n, 15782 Santiago de Compostela, Spain
| | - Cibell Resch
- Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - María I. Loza
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS). Universidade de Santiago de Compostela. Avda. de Barcelona, s/n, 15782 Santiago de Compostela, Spain
| | - Marián Castro
- Center for Research in Molecular Medicine and Chronic Diseases (CIMUS). Universidade de Santiago de Compostela. Avda. de Barcelona, s/n, 15782 Santiago de Compostela, Spain
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Marcello Leopoldo
- Dipartimento di Farmacia−Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona, 4, 70125 Bari, Italy
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7
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Labus J, Röhrs KF, Ackmann J, Varbanov H, Müller FE, Jia S, Jahreis K, Vollbrecht AL, Butzlaff M, Schill Y, Guseva D, Böhm K, Kaushik R, Bijata M, Marin P, Chaumont-Dubel S, Zeug A, Dityatev A, Ponimaskin E. Amelioration of Tau pathology and memory deficits by targeting 5-HT7 receptor. Prog Neurobiol 2021. [PMID: 32841723 DOI: 10.1016/j.pneurobiol.2020.101900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Tauopathies comprise a heterogeneous family of neurodegenerative diseases characterized by pathological accumulation of hyperphosphorylated Tau protein. Pathological changes in serotonergic signaling have been associated with tauopathy etiology, but the underlying mechanisms remain poorly understood. Here, we studied the role of the serotonin receptor 7 (5-HT7R), in a mouse model of tauopathy induced by overexpressing the human Tau[R406W] mutant associated with inherited forms of frontotemporal dementia. We showed that the constitutive 5-HT7R activity is required for Tau hyperphosphorylation and formation of highly bundled Tau structures (HBTS) through G-protein-independent, CDK5-dependent mechanism. We also showed that 5-HT7R physically interacts with CDK5. At the systemic level, 5-HT7R-mediated CDK5 activation induces HBTS leading to neuronal death, reduced long-term potentiation (LTP), and impaired memory in mice. Specific blockade of constitutive 5-HT7R activity in neurons that overexpressed Tau[R406W] prevents Tau hyperphosphorylation, aggregation, and neurotoxicity. Moreover, 5-HT7R knockdown in the prefrontal cortex fully abrogates Tau[R406W]-induced LTP deficits and memory impairments. Thus, 5-HT7R/CDK5 signaling emerged as a new, promising target for tauopathy treatments.
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Affiliation(s)
- Josephine Labus
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Kian-Fritz Röhrs
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany; Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jana Ackmann
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Hristo Varbanov
- Instituite of Neurophysiology, Hannover Medical School, Hannover, Germany; German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Franziska E Müller
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Shaobo Jia
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Kathrin Jahreis
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Anna-Lena Vollbrecht
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Malte Butzlaff
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Yvonne Schill
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Daria Guseva
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Katrin Böhm
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Rahul Kaushik
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Monika Bijata
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany; Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology of the Polish Academy of Science, Warsaw, Poland
| | - Philippe Marin
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | | | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany; Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany.
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany; Institute of Neuroscience, Lobachevsky State University of Nizhni Novgorod, Russia.
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8
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Hinze L, Schreek S, Zeug A, Ponimaskin E, Labrosse R, Degar J, Bornhauser B, Bourquin JP, Stanulla M, Gutierrez A. Abstract PR06: Spatial sequestration of GSKα as a cellular response to amino acid starvation. Cancer Res 2020. [DOI: 10.1158/1538-7445.epimetab20-pr06] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The ability of cells to tolerate amino acid starvation is fundamental to survival under stress. Some cancer cells are vulnerable to asparagine depletion, which is exploited therapeutically using asparaginase. We recently found that Wnt pathway activation induces a profound therapeutic vulnerability to asparaginase in acute leukemia and in colorectal cancer (Hinze et al., In press; Hinze et al., 2019). This effect is mediated by a β-catenin independent branch of Wnt signaling termed Wnt-dependent stabilization of proteins (Wnt/STOP), which inhibits GSK3-dependent protein degradation. Asparaginase resistance is uniquely dependent on GSK3α because its inhibition fully phenocopied Wnt-induced sensitization to asparaginase (p < 0.0001), whereas selective GSK3β inhibition had no effect (p=ns). This is surprising because GSK3α and GSK3β are closely related paralogs thought to be redundant for many of their biologic functions. Thus, we set out to define why asparaginase resistance is selectively dependent on GSK3α activity. To define the GSK3α domains responsible for asparaginase resistance, we tested whether resistance could be restored by expression of a series of GSK3 alleles in which the N-terminal, kinase, and C-terminal domains of GSK3α and GSK3β were swapped in various configurations. Fusing the N-terminus of GSK3α to the kinase and C-terminal domains of GSK3β fully restored asparaginase resistance in GSK3α depleted T-ALL (p<0.0001). By contrast, fusing the N-terminus of GSK3β to the kinase and C-terminus of GSK3α had no activity (p=ns). To investigate how the N-terminus of GSK3α regulates asparaginase response, we first applied structural prediction algorithms, which revealed that the N-terminal domain of GSK3α is a low-complexity domain, a feature lacking in its paralog GSK3β. Immunofluorescence confocal microscopy revealed that this domain mediates spatial sequestration of GSK3α into membrane-less cytoplasmic bodies in response to amino acid starvation. GSK3a bodies appeared to be distinct from known phase-separated compartments such as stress granules and aggresomes. However, GSK3α bodies colocalized with K48-linked ubiquitin and the proteasome, suggesting that they assemble the cellular machinery for protein ubiquitination and proteasomal degradation. This suggests that GSK3α body formation promotes efficient generation of amino acids via catabolic protein degradation, and promotes survival during starvation in normal and malignant cells. Importantly, GSK3α body formation was stimulated in response to starvation of several amino acids (p<0.0001), and promoted survival of normal cells in response to amino acid starvation. In human cancer, GSK3α body formation predicted response to asparaginase resistance (p<0.0001), and sensitivity to asparaginase combined with a GSK3a inhibitor (p<0.0001). We propose that GSK3α body formation provides a cellular mechanism to promote catalytic efficiency of protein degradation as an adaptive response to amino acid starvation.
Citation Format: Laura Hinze, Sabine Schreek, Andre Zeug, Evgeni Ponimaskin, Roxane Labrosse, James Degar, Beat Bornhauser, Jean-Pierre Bourquin, Martin Stanulla, Alejandro Gutierrez. Spatial sequestration of GSKα as a cellular response to amino acid starvation [abstract]. In: Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020; 2020 Oct 15-16. Philadelphia (PA): AACR; Cancer Res 2020;80(23 Suppl):Abstract nr PR06.
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Affiliation(s)
| | | | - Andre Zeug
- 2Hannover Medical School, Hannover, Germany,
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9
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Müller FE, Schade SK, Cherkas V, Stopper L, Breithausen B, Minge D, Varbanov H, Wahl-Schott C, Antoniuk S, Domingos C, Compan V, Kirchhoff F, Henneberger C, Ponimaskin E, Zeug A. Serotonin receptor 4 regulates hippocampal astrocyte morphology and function. Glia 2020; 69:872-889. [PMID: 33156956 DOI: 10.1002/glia.23933] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 10/15/2020] [Accepted: 10/19/2020] [Indexed: 12/25/2022]
Abstract
Astrocytes are an important component of the multipartite synapse and crucial for proper neuronal network function. Although small GTPases of the Rho family are powerful regulators of cellular morphology, the signaling modules of Rho-mediated pathways in astrocytes remain enigmatic. Here we demonstrated that the serotonin receptor 4 (5-HT4 R) is expressed in hippocampal astrocytes, both in vitro and in vivo. Through fluorescence microscopy, we established that 5-HT4 R activation triggered RhoA activity via Gα13 -mediated signaling, which boosted filamentous actin assembly, leading to morphological changes in hippocampal astrocytes. We investigated the effects of these 5-HT4 R-mediated changes in mixed cultures and in acute slices, in which 5-HT4 R was expressed exclusively in astrocytes. In both systems, 5-HT4 R-RhoA signaling changed glutamatergic synaptic transmission: It increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in mixed cultures and reduced the paired-pulse-ratio (PPR) of field excitatory postsynaptic potentials (fEPSPs) in acute slices. Overall, our present findings demonstrate that astrocytic 5-HT4 R-Gα13 -RhoA signaling is a previously unrecognized molecular pathway involved in the functional regulation of excitatory synaptic circuits.
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Affiliation(s)
| | - Sophie K Schade
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Volodymyr Cherkas
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Laura Stopper
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Björn Breithausen
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Daniel Minge
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Hristo Varbanov
- Institute of Neurophysiology, Hannover Medical School, Hannover, Germany
| | | | - Svitlana Antoniuk
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany.,Nencki Institute of Experimental Biology of the Polish Academy of Science, Warsaw, Poland
| | - Catia Domingos
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Valérie Compan
- Department of Sciences, Brain, Anorexia & Addiction, Nîmes University, Nîmes, France
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Institute of Neurology, University College London, London, UK
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany.,Institute of Neuroscience, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
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10
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Labus J, Röhrs KF, Ackmann J, Varbanov H, Müller FE, Jia S, Jahreis K, Vollbrecht AL, Butzlaff M, Schill Y, Guseva D, Böhm K, Kaushik R, Bijata M, Marin P, Chaumont-Dubel S, Zeug A, Dityatev A, Ponimaskin E. Amelioration of Tau pathology and memory deficits by targeting 5-HT7 receptor. Prog Neurobiol 2020; 197:101900. [PMID: 32841723 DOI: 10.1016/j.pneurobio.2020.101900] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 07/21/2020] [Accepted: 08/17/2020] [Indexed: 01/01/2023]
Abstract
Tauopathies comprise a heterogeneous family of neurodegenerative diseases characterized by pathological accumulation of hyperphosphorylated Tau protein. Pathological changes in serotonergic signaling have been associated with tauopathy etiology, but the underlying mechanisms remain poorly understood. Here, we studied the role of the serotonin receptor 7 (5-HT7R), in a mouse model of tauopathy induced by overexpressing the human Tau[R406W] mutant associated with inherited forms of frontotemporal dementia. We showed that the constitutive 5-HT7R activity is required for Tau hyperphosphorylation and formation of highly bundled Tau structures (HBTS) through G-protein-independent, CDK5-dependent mechanism. We also showed that 5-HT7R physically interacts with CDK5. At the systemic level, 5-HT7R-mediated CDK5 activation induces HBTS leading to neuronal death, reduced long-term potentiation (LTP), and impaired memory in mice. Specific blockade of constitutive 5-HT7R activity in neurons that overexpressed Tau[R406W] prevents Tau hyperphosphorylation, aggregation, and neurotoxicity. Moreover, 5-HT7R knockdown in the prefrontal cortex fully abrogates Tau[R406W]-induced LTP deficits and memory impairments. Thus, 5-HT7R/CDK5 signaling emerged as a new, promising target for tauopathy treatments.
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Affiliation(s)
- Josephine Labus
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Kian-Fritz Röhrs
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany; Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jana Ackmann
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Hristo Varbanov
- Instituite of Neurophysiology, Hannover Medical School, Hannover, Germany; German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Franziska E Müller
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Shaobo Jia
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Kathrin Jahreis
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Anna-Lena Vollbrecht
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Malte Butzlaff
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Yvonne Schill
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Daria Guseva
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Katrin Böhm
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Rahul Kaushik
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Monika Bijata
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany; Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology of the Polish Academy of Science, Warsaw, Poland
| | - Philippe Marin
- IGF, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | | | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany; Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany.
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany; Institute of Neuroscience, Lobachevsky State University of Nizhni Novgorod, Russia.
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11
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Gorinski N, Wojciechowski D, Guseva D, Abdel Galil D, Mueller FE, Wirth A, Thiemann S, Zeug A, Schmidt S, Zareba-Kozioł M, Wlodarczyk J, Skryabin BV, Glage S, Fischer M, Al-Samir S, Kerkenberg N, Hohoff C, Zhang W, Endeward V, Ponimaskin E. DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels. J Biol Chem 2020; 295:5970-5983. [PMID: 32184353 DOI: 10.1074/jbc.ra119.011049] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 03/13/2020] [Indexed: 12/21/2022] Open
Abstract
Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7 -/- mice. Although palmitoylation of barttin in kidneys of Zdhhc7 -/- animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7 -/- mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.
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Affiliation(s)
- Nataliya Gorinski
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | | | - Daria Guseva
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Dalia Abdel Galil
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Franziska E Mueller
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Alexander Wirth
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Stefan Thiemann
- Institute for Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Silke Schmidt
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Monika Zareba-Kozioł
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Jakub Wlodarczyk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Boris V Skryabin
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, 48149 Münster, Germany
| | - Silke Glage
- Institute for Laboratory Animal Science, Hannover Medical School, 30625 Hannover, Germany
| | - Martin Fischer
- Institute for Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Samer Al-Samir
- Institute of Vegetative Physiology, Hannover Medical School, 30625 Hannover, Germany
| | - Nicole Kerkenberg
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, 48149 Münster, Germany
| | - Christa Hohoff
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany
| | - Weiqi Zhang
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, 48149 Münster, Germany
| | - Volker Endeward
- Institute of Vegetative Physiology, Hannover Medical School, 30625 Hannover, Germany
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany.
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12
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King CM, Bohmbach K, Minge D, Delekate A, Zheng K, Reynolds J, Rakers C, Zeug A, Petzold GC, Rusakov DA, Henneberger C. Local Resting Ca 2+ Controls the Scale of Astroglial Ca 2+ Signals. Cell Rep 2020; 30:3466-3477.e4. [PMID: 32160550 PMCID: PMC7068654 DOI: 10.1016/j.celrep.2020.02.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/21/2019] [Accepted: 02/06/2020] [Indexed: 02/07/2023] Open
Abstract
Astroglia regulate neurovascular coupling while engaging in signal exchange with neurons. The underlying cellular machinery is thought to rely on astrocytic Ca2+ signals, but what controls their amplitude and waveform is poorly understood. Here, we employ time-resolved two-photon excitation fluorescence imaging in acute hippocampal slices and in cortex in vivo to find that resting [Ca2+] predicts the scale (amplitude) and the maximum (peak) of astroglial Ca2+ elevations. We bidirectionally manipulate resting [Ca2+] by uncaging intracellular Ca2+ or Ca2+ buffers and use ratiometric imaging of a genetically encoded Ca2+ indicator to establish that alterations in resting [Ca2+] change co-directionally the peak level and anti-directionally the amplitude of local Ca2+ transients. This relationship holds for spontaneous and for induced (for instance by locomotion) Ca2+ signals. Our findings uncover a basic generic rule of Ca2+ signal formation in astrocytes, thus also associating the resting Ca2+ level with the physiological "excitability" state of astroglia.
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Affiliation(s)
- Claire M King
- Institute of Neurology, University College London, London, UK
| | - Kirsten Bohmbach
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Daniel Minge
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Andrea Delekate
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Kaiyu Zheng
- Institute of Neurology, University College London, London, UK
| | - James Reynolds
- Institute of Neurology, University College London, London, UK
| | - Cordula Rakers
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; Department of Neurology, University Hospital Bonn, Bonn, Germany
| | | | - Christian Henneberger
- Institute of Neurology, University College London, London, UK; Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
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13
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Schill Y, Bijata M, Kopach O, Cherkas V, Abdel-Galil D, Böhm K, Schwab MH, Matsuda M, Compan V, Basu S, Bijata K, Wlodarczyk J, Bard L, Cole N, Dityatev A, Zeug A, Rusakov DA, Ponimaskin E. Serotonin 5-HT 4 receptor boosts functional maturation of dendritic spines via RhoA-dependent control of F-actin. Commun Biol 2020; 3:76. [PMID: 32060357 PMCID: PMC7021812 DOI: 10.1038/s42003-020-0791-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/23/2020] [Indexed: 01/24/2023] Open
Abstract
Activity-dependent remodeling of excitatory connections underpins memory formation in the brain. Serotonin receptors are known to contribute to such remodeling, yet the underlying molecular machinery remains poorly understood. Here, we employ high-resolution time-lapse FRET imaging in neuroblastoma cells and neuronal dendrites to establish that activation of serotonin receptor 5-HT4 (5-HT4R) rapidly triggers spatially-restricted RhoA activity and G13-mediated phosphorylation of cofilin, thus locally boosting the filamentous actin fraction. In neuroblastoma cells, this leads to cell rounding and neurite retraction. In hippocampal neurons in situ, 5-HT4R-mediated RhoA activation triggers maturation of dendritic spines. This is paralleled by RhoA-dependent, transient alterations in cell excitability, as reflected by increased spontaneous synaptic activity, apparent shunting of evoked synaptic responses, and enhanced long-term potentiation of excitatory transmission. The 5-HT4R/G13/RhoA signaling thus emerges as a previously unrecognized molecular pathway underpinning use-dependent functional remodeling of excitatory synaptic connections.
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Affiliation(s)
- Yvonne Schill
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
| | - Monika Bijata
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteur Str. 3, 02-093, Warsaw, Poland
| | - Olga Kopach
- UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Volodymyr Cherkas
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
| | - Dalia Abdel-Galil
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
| | - Katrin Böhm
- German Center for Neurodegenerative Diseases (DZNE), Leipziger Str. 44, 39120, Magdeburg, Germany
| | - Markus H Schwab
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
| | - Michiyuki Matsuda
- Bioimaging and Cell Signaling, Kyoto University, Kyoto, 606-8501, Japan
| | | | - Subhadip Basu
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
- Computer Science and Engineering, Jadavpur University, Kolkata, 700032, India
| | - Krystian Bijata
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteur Str. 3, 02-093, Warsaw, Poland
| | - Jakub Wlodarczyk
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteur Str. 3, 02-093, Warsaw, Poland
| | - Lucie Bard
- UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Nicholas Cole
- UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE), Leipziger Str. 44, 39120, Magdeburg, Germany
- Medical Faculty, Otto-von-Guericke-University, Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany
| | - Dmitri A Rusakov
- UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Hannover Medical School, Carl-Neuberg Str. 1, 30625, Hannover, Germany.
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Xu J, Zeug A, Riederer B, Yeruva S, Griesbeck O, Daniel H, Tuo B, Ponimaskin E, Dong H, Seidler U. Calcium-sensing receptor regulates intestinal dipeptide absorption via Ca 2+ signaling and IK Ca activation. Physiol Rep 2020; 8:e14337. [PMID: 31960592 PMCID: PMC6971415 DOI: 10.14814/phy2.14337] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although absorption of di- and tripeptides into intestinal epithelial cells occurs via the peptide transporter 1 (PEPT1, also called solute carrier family 15 member 1 (SLC15A1)), the detailed regulatory mechanisms are not fully understood. We examined: (a) whether dipeptide absorption in villous enterocytes is associated with a rise in cytosolic Ca2+ ([Ca2+ ]cyt ), (b) whether the calcium sensing receptor (CaSR) is involved in dipeptide-elicited [Ca2+ ]cyt signaling, and (c) what potential consequences of [Ca2+ ]cyt signaling may enhance enterocyte dipeptide absorption. Dipeptide Gly-Sar and CaSR agonist spermine markedly raised [Ca2+ ]cyt in villous enterocytes, which was abolished by NPS-2143, a selective CaSR antagonist and U73122, an phospholipase C (PLC) inhibitor. Apical application of Gly-Sar induced a jejunal short-circuit current (Isc), which was reduced by NPS-2143. CaSR expression was identified in the lamina propria and on the basal enterocyte membrane of mouse jejunal mucosa in both WT and Slc15a1-/- animals, but Gly-Sar-induced [Ca2+ ]cyt signaling was significantly decreased in Slc15a1-/- villi. Clotrimazole and TRM-34, two selective blockers of the intermediate conductance Ca2+ -activated K+ channel (IKCa ), but not iberiotoxin, a selective blocker of the large-conductance K+ channel (BKCa ) and apamin, a selective blocker of the small-conductance K+ channel (SKCa ), significantly inhibited Gly-Sar-induced Isc in native tissues. We reveal a novel CaSR-PLC-Ca2+ -IKCa pathway in the regulation of small intestinal dipeptide absorption, which may be exploited as a target for future drug development in human nutritional disorders.
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Affiliation(s)
- Jingyu Xu
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Andre Zeug
- Cellular NeurophysiologyHannover Medical SchoolHannoverGermany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | - Sunil Yeruva
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | | | - Hannelore Daniel
- Nutritional PhysiologyTechnical University of MunichFreisingGermany
| | - Biguang Tuo
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | | | - Hui Dong
- Department of MedicineUniversity of California, San DiegoLa JollaCAUSA
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
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Tian Q, Schröder L, Schwarz Y, Flockerzi A, Kaestner L, Zeug A, Bruns D, Lipp P. Large scale, unbiased analysis of elementary calcium signaling events in cardiac myocytes. J Mol Cell Cardiol 2019; 135:79-89. [DOI: 10.1016/j.yjmcc.2019.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/26/2019] [Accepted: 08/12/2019] [Indexed: 12/12/2022]
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Prasad S, Ponimaskin E, Zeug A. Serotonin receptor oligomerization regulates cAMP-based signaling. J Cell Sci 2019; 132:jcs.230334. [PMID: 31371490 DOI: 10.1242/jcs.230334] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 07/22/2019] [Indexed: 11/20/2022] Open
Abstract
Protein-protein interaction is often investigated using quantitative molecular microscopy with Förster resonant energy transfer (FRET). Here, we combined 'linear unmixing FRET' (lux-FRET) with the simultaneous application of a FRET-based biosensor for cAMP to investigate the oligomerization between the 5-HT7 receptor (5-HT7R, also known as HTR7) and the 5-HT1A receptor (5-HT1AR, also known as HTR1A) and its importance for cAMP signaling. We found that the 5-HT7R not only stimulates cAMP production, but also forms hetero-oligomers with 5-HT1AR, which blocks the inhibitory effect of the latter. 5-HT7R signaling, however, is not affected by this hetero-oligomerization. By modeling the kinetics of intracellular cAMP level changes in relation to the 5-HT7R:5-HT1AR stoichiometry, we were able to decipher the complex signaling characteristics of endogenous serotonin receptors in cultured hippocampal neurons. Our findings indicate that serotonergic signaling is not only modulated by the concentration of an individual receptor but also by its specific interaction with other receptors in endogenous systems. We conclude that the regulated ratio of serotonin receptors in immature and mature neurons may be critically involved in both the onset and response to treatments of psychiatric diseases, such as anxiety and depression.
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Affiliation(s)
- Sonal Prasad
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany.,Department of Behavioral Neurogenomics, Institute of Cytology and Genetics, Lavrentyeva av., 10 630090, Novosibirsk, Russia
| | - Andre Zeug
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
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17
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Hogendorf AS, Hogendorf A, Popiołek-Barczyk K, Ciechanowska A, Mika J, Satała G, Walczak M, Latacz G, Handzlik J, Kieć-Kononowicz K, Ponimaskin E, Schade S, Zeug A, Bijata M, Kubicki M, Kurczab R, Lenda T, Staroń J, Bugno R, Duszyńska B, Pilarski B, Bojarski AJ. Fluorinated indole-imidazole conjugates: Selective orally bioavailable 5-HT 7 receptor low-basicity agonists, potential neuropathic painkillers. Eur J Med Chem 2019; 170:261-275. [PMID: 30904783 DOI: 10.1016/j.ejmech.2019.03.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/06/2019] [Accepted: 03/06/2019] [Indexed: 12/31/2022]
Abstract
The 5-HT7 receptor has recently gained much attention due to its involvement in multiple physiological functions and diseases. The insufficient quality of the available molecular probes prompted design of fluorinated 3-(1-alkyl-1H-imidazol-5-yl)-1H-indoles as a new generation of selective 5-HT7 receptor agonists. A potent and drug-like agonist, 3-(1-ethyl-1H-imidazol-5-yl)-5-iodo-4-fluoro-1H-indole (AGH-192, 35, Ki 5-HT7R = 4 nM), was identified by optimizing the halogen bond formation with Ser5.42 as the supposed partner. The compound was characterized by excellent water solubility, high selectivity over related CNS targets, high metabolic stability, oral bioavailability and low cytotoxicity. Rapid absorption into the blood, medium half-life and a high peak concentration in the brain Cmax = 1069 ng/g were found after i.p. (2.5 mg/kg) administration in mice. AGH-192 may thus serve as the long-sought tool compound in the study of 5-HT7 receptor function, as well as a potential analgesic, indicated by the antinociceptive effect observed in a mouse model of neuropathic pain.
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Affiliation(s)
- Adam S Hogendorf
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Agata Hogendorf
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | | | - Agata Ciechanowska
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Joanna Mika
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Grzegorz Satała
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Maria Walczak
- Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Street, 30-688 Kraków, Poland
| | - Gniewomir Latacz
- Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Street, 30-688 Kraków, Poland
| | - Jadwiga Handzlik
- Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Street, 30-688 Kraków, Poland
| | - Katarzyna Kieć-Kononowicz
- Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Street, 30-688 Kraków, Poland
| | - Evgeni Ponimaskin
- Center of Physiology, Hannover Medical School, 1 Carl-Neuberg Street, 30625 Hannover, Germany
| | - Sophie Schade
- Center of Physiology, Hannover Medical School, 1 Carl-Neuberg Street, 30625 Hannover, Germany
| | - Andre Zeug
- Center of Physiology, Hannover Medical School, 1 Carl-Neuberg Street, 30625 Hannover, Germany
| | - Monika Bijata
- Center of Physiology, Hannover Medical School, 1 Carl-Neuberg Street, 30625 Hannover, Germany; Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warszawa, Poland
| | - Maciej Kubicki
- Adam Mickiewicz University, Faculty of Chemistry, 89b Umultowska Street, 61-614 Poznań, Poland
| | - Rafał Kurczab
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Tomasz Lenda
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Jakub Staroń
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Ryszard Bugno
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | - Beata Duszyńska
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland
| | | | - Andrzej J Bojarski
- Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, 30-343 Kraków, Poland.
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18
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Ulc A, Zeug A, Bauch J, van Leeuwen S, Kuhlmann T, ffrench-Constant C, Ponimaskin E, Faissner A. The guanine nucleotide exchange factor Vav3 modulates oligodendrocyte precursor differentiation and supports remyelination in white matter lesions. Glia 2018; 67:376-392. [DOI: 10.1002/glia.23548] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Annika Ulc
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
| | - Andre Zeug
- Cellular Neurophysiology, Centre for Physiology; Hannover Medical School; Hannover Germany
| | - Juliane Bauch
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
| | - Simon van Leeuwen
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
| | - Tanja Kuhlmann
- Institute of Neuropathology; University Hospital Münster; Germany
| | | | - Evgeni Ponimaskin
- Cellular Neurophysiology, Centre for Physiology; Hannover Medical School; Hannover Germany
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology; Ruhr-University Bochum; Germany
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19
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Rose CR, Felix L, Zeug A, Dietrich D, Reiner A, Henneberger C. Astroglial Glutamate Signaling and Uptake in the Hippocampus. Front Mol Neurosci 2018; 10:451. [PMID: 29386994 PMCID: PMC5776105 DOI: 10.3389/fnmol.2017.00451] [Citation(s) in RCA: 122] [Impact Index Per Article: 20.3] [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: 11/20/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022] Open
Abstract
Astrocytes have long been regarded as essentially unexcitable cells that do not contribute to active signaling and information processing in the brain. Contrary to this classical view, it is now firmly established that astrocytes can specifically respond to glutamate released from neurons. Astrocyte glutamate signaling is initiated upon binding of glutamate to ionotropic and/or metabotropic receptors, which can result in calcium signaling, a major form of glial excitability. Release of so-called gliotransmitters like glutamate, ATP and D-serine from astrocytes in response to activation of glutamate receptors has been demonstrated to modulate various aspects of neuronal function in the hippocampus. In addition to receptors, glutamate binds to high-affinity, sodium-dependent transporters, which results in rapid buffering of synaptically-released glutamate, followed by its removal from the synaptic cleft through uptake into astrocytes. The degree to which astrocytes modulate and control extracellular glutamate levels through glutamate transporters depends on their expression levels and on the ionic driving forces that decrease with ongoing activity. Another major determinant of astrocytic control of glutamate levels could be the precise morphological arrangement of fine perisynaptic processes close to synapses, defining the diffusional distance for glutamate, and the spatial proximity of transporters in relation to the synaptic cleft. In this review, we will present an overview of the mechanisms and physiological role of glutamate-induced ion signaling in astrocytes in the hippocampus as mediated by receptors and transporters. Moreover, we will discuss the relevance of astroglial glutamate uptake for extracellular glutamate homeostasis, focusing on how activity-induced dynamic changes of perisynaptic processes could shape synaptic transmission at glutamatergic synapses.
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Affiliation(s)
- Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Lisa Felix
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Dirk Dietrich
- Department of Neurosurgery, University of Bonn Medical School, Bonn, Germany
| | - Andreas Reiner
- Cellular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany.,German Center for Degenerative Diseases (DZNE), Bonn, Germany.,Institute of Neurology, University College London, London, United Kingdom
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20
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Ruhe F, Olling A, Abromeit R, Rataj D, Grieschat M, Zeug A, Gerhard R, Alekov A. Overexpression of the Endosomal Anion/Proton Exchanger ClC-5 Increases Cell Susceptibility toward Clostridium difficile Toxins TcdA and TcdB. Front Cell Infect Microbiol 2017; 7:67. [PMID: 28348980 PMCID: PMC5346576 DOI: 10.3389/fcimb.2017.00067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 08/11/2016] [Accepted: 02/21/2017] [Indexed: 12/30/2022] Open
Abstract
Virulent C. difficile toxins TcdA and TcdB invade host intestinal epithelia by endocytosis and use the acidic environment of intracellular vesicles for further processing and activation. We investigated the role of ClC-5, a chloride/proton exchanger expressed in the endosomes of gastrointestinal epithelial cells, in the activation and processing of C. difficile toxins. Enhanced intoxication by TcdA and TcdB was observed in cells expressing ClC-5 but not ClC-4, another chloride/proton exchanger with similar function but different localization. In accordance with the established physiological function of ClC-5, its expression lowered the endosomal pH in HEK293T cells by approximately 0.6 units and enhanced approximately 5-fold the internalization of TcdA. In colon HT29 cells, 34% of internalized TcdA localized to ClC-5-containing vesicles defined by colocalization with Rab5, Rab4a, and Rab7 as early and early-to-late of endosomes but not as Rab11-containing recycling endosomes. Impairing the cellular uptake of TcdA by deleting the toxin CROPs domain did not abolish the effects of ClC-5. In addition, the transport-incompetent mutant ClC-5 E268Q similarly enhanced both endosomal acidification and intoxication by TcdA but facilitated the internalization of the toxin to a lower extent. These data suggest that ClC-5 enhances the cytotoxic action of C. difficile toxins by accelerating the acidification and maturation of vesicles of the early and early-to-late endosomal system. The dispensable role of electrogenic ion transport suggests that the voltage-dependent nonlinear capacitances of mammalian CLC transporters serve important physiological functions. Our data shed light on the intersection between the endocytotic cascade of host epithelial cells and the internalization pathway of the large virulence C. difficile toxins. Identifying ClC-5 as a potential specific host ion transporter hijacked by toxins produced by pathogenic bacteria widens the horizon of possibilities for novel therapies of life-threatening gastrointestinal infections.
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Affiliation(s)
- Frederike Ruhe
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Alexandra Olling
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | - Rasmus Abromeit
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Dennis Rataj
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | | | - Andre Zeug
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Ralf Gerhard
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | - Alexi Alekov
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
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21
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Hassouna I, Ott C, Wüstefeld L, Offen N, Neher RA, Mitkovski M, Winkler D, Sperling S, Fries L, Goebbels S, Vreja IC, Hagemeyer N, Dittrich M, Rossetti MF, Kröhnert K, Hannke K, Boretius S, Zeug A, Höschen C, Dandekar T, Dere E, Neher E, Rizzoli SO, Nave KA, Sirén AL, Ehrenreich H. Revisiting adult neurogenesis and the role of erythropoietin for neuronal and oligodendroglial differentiation in the hippocampus. Mol Psychiatry 2016; 21:1752-1767. [PMID: 26809838 PMCID: PMC5193535 DOI: 10.1038/mp.2015.212] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 11/10/2015] [Accepted: 11/13/2015] [Indexed: 12/22/2022]
Abstract
Recombinant human erythropoietin (EPO) improves cognitive performance in neuropsychiatric diseases ranging from schizophrenia and multiple sclerosis to major depression and bipolar disease. This consistent EPO effect on cognition is independent of its role in hematopoiesis. The cellular mechanisms of action in brain, however, have remained unclear. Here we studied healthy young mice and observed that 3-week EPO administration was associated with an increased number of pyramidal neurons and oligodendrocytes in the hippocampus of ~20%. Under constant cognitive challenge, neuron numbers remained elevated until >6 months of age. Surprisingly, this increase occurred in absence of altered cell proliferation or apoptosis. After feeding a 15N-leucine diet, we used nanoscopic secondary ion mass spectrometry, and found that in EPO-treated mice, an equivalent number of neurons was defined by elevated 15N-leucine incorporation. In EPO-treated NG2-Cre-ERT2 mice, we confirmed enhanced differentiation of preexisting oligodendrocyte precursors in the absence of elevated DNA synthesis. A corresponding analysis of the neuronal lineage awaits the identification of suitable neuronal markers. In cultured neurospheres, EPO reduced Sox9 and stimulated miR124, associated with advanced neuronal differentiation. We are discussing a resulting working model in which EPO drives the differentiation of non-dividing precursors in both (NG2+) oligodendroglial and neuronal lineages. As endogenous EPO expression is induced by brain injury, such a mechanism of adult neurogenesis may be relevant for central nervous system regeneration.
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Affiliation(s)
- I Hassouna
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany,On leave of absence from Physiology
Unit, Zoology Department, Faculty of Science, Menoufia University,
Al Minufya, Egypt
| | - C Ott
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - L Wüstefeld
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - N Offen
- Department of Neurosurgery,
University of Würzburg, Würzburg,
Germany
| | - R A Neher
- Evolutionary Dynamics and Biophysics,
Max Planck Institute for Developmental Biology,
Tübingen, Germany
| | - M Mitkovski
- Light Microscopy Facility, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - D Winkler
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - S Sperling
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - L Fries
- Department of Neurosurgery,
University of Würzburg, Würzburg,
Germany
| | - S Goebbels
- Department of Neurogenetics, Max
Planck Institute of Experimental Medicine,
Göttingen, Germany
| | - I C Vreja
- Department of Neuro- and Sensory
Physiology, University Medical Center
Göttingen, Germany,International Max Planck Research
School Molecular Biology, Göttingen,
Germany
| | - N Hagemeyer
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - M Dittrich
- Department of Bioinformatics,
Biocenter, University of Würzburg, Würzburg,
Germany
| | - M F Rossetti
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - K Kröhnert
- Department of Neuro- and Sensory
Physiology, University Medical Center
Göttingen, Germany
| | - K Hannke
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - S Boretius
- Department of Diagnostic Radiology,
Christian-Albrechts-Universität, Kiel,
Germany
| | - A Zeug
- Cellular Neurophysiology, Hannover
Medical School, Hannover, Germany
| | - C Höschen
- Department of Ecology and Ecosystem
Management, Lehrstuhl für Bodenkunde, Technische Universität
München, Freising-Weihenstephan,
Germany
| | - T Dandekar
- Department of Bioinformatics,
Biocenter, University of Würzburg, Würzburg,
Germany
| | - E Dere
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany
| | - E Neher
- Department of Membrane Biophysics,
Max Planck Institute for Biophysical Chemistry,
Göttingen, Germany,DFG Center for Nanoscale Microscopy
and Molecular Physiology of the Brain, Göttingen,
Germany
| | - S O Rizzoli
- Department of Neuro- and Sensory
Physiology, University Medical Center
Göttingen, Germany,DFG Center for Nanoscale Microscopy
and Molecular Physiology of the Brain, Göttingen,
Germany
| | - K-A Nave
- Department of Neurogenetics, Max
Planck Institute of Experimental Medicine,
Göttingen, Germany,DFG Center for Nanoscale Microscopy
and Molecular Physiology of the Brain, Göttingen,
Germany
| | - A-L Sirén
- Department of Neurosurgery,
University of Würzburg, Würzburg,
Germany
| | - H Ehrenreich
- Clinical Neuroscience, Max Planck
Institute of Experimental Medicine, Göttingen,
Germany,DFG Center for Nanoscale Microscopy
and Molecular Physiology of the Brain, Göttingen,
Germany,Clinical Neuroscience, Max Planck Institute of
Experimental Medicine, Hermann-Rein-Str.3,
Göttingen
37075, Germany. E-mail:
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22
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Konopka A, Zeug A, Skupien A, Kaza B, Mueller F, Chwedorowicz A, Ponimaskin E, Wilczynski GM, Dzwonek J. Cleavage of Hyaluronan and CD44 Adhesion Molecule Regulate Astrocyte Morphology via Rac1 Signalling. PLoS One 2016; 11:e0155053. [PMID: 27163367 PMCID: PMC4862642 DOI: 10.1371/journal.pone.0155053] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Accepted: 04/22/2016] [Indexed: 11/19/2022] Open
Abstract
Communication of cells with their extracellular environment is crucial to fulfill their function in physiological and pathophysiological conditions. The literature data provide evidence that such a communication is also important in case of astrocytes. Mechanisms that contribute to the interaction between astrocytes and extracellular matrix (ECM) proteins are still poorly understood. Hyaluronan is the main component of ECM in the brain, where its major receptor protein CD44 is expressed by a subset of astrocytes. Considering the fact that functions of astrocytes are tightly coupled with changes in their morphology (e.g.: glutamate clearance in the synaptic cleft, migration, astrogliosis), we investigated the influence of hyaluronan cleavage by hyaluronidase, knockdown of CD44 by specific shRNA and CD44 overexpression on astrocyte morphology. Our results show that hyaluronidase treatment, as well as knockdown of CD44, in astrocytes result in a "stellate"-like morphology, whereas overexpression of CD44 causes an increase in cell body size and changes the shape of astrocytes into flattened cells. Moreover, as a dynamic reorganization of the actin cytoskeleton is supposed to be responsible for morphological changes of cells, and this reorganization is controlled by small GTPases of the Rho family, we hypothesized that GTPase Rac1 acts as a downstream effector for hyaluronan and CD44 in astrocytes. We used FRET-based biosensor and a dominant negative mutant of Rac1 to investigate the involvement of Rac1 activity in hyaluronidase- and CD44-dependent morphological changes of astrocytes. Both, hyaluronidase treatment and knockdown of CD44, enhances Rac1 activity while overexpression of CD44 reduces the activity state in astrocytes. Furthermore, morphological changes were blocked by specific inhibition of Rac1 activity. These findings indicate for the first time that regulation of Rac1 activity is responsible for hyaluronidase and CD44-driven morphological changes of astrocytes.
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Affiliation(s)
- Anna Konopka
- Laboratory of Molecular and Systemic Neuromorphology, The Nencki Institute of Experimental Biology, 02–093, Warsaw, ul. Pasteura 3, Poland
| | - Andre Zeug
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, 30625, Hannover, Germany
| | - Anna Skupien
- Laboratory of Molecular and Systemic Neuromorphology, The Nencki Institute of Experimental Biology, 02–093, Warsaw, ul. Pasteura 3, Poland
| | - Beata Kaza
- Laboratory of Molecular Neurobiology, Neurobiology Center, The Nencki Institute of Experimental Biology, 02–093, Warsaw, ul. Pasteura 3, Poland
| | - Franziska Mueller
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, 30625, Hannover, Germany
| | - Agnieszka Chwedorowicz
- Laboratory of Molecular and Systemic Neuromorphology, The Nencki Institute of Experimental Biology, 02–093, Warsaw, ul. Pasteura 3, Poland
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, 30625, Hannover, Germany
| | - Grzegorz M. Wilczynski
- Laboratory of Molecular and Systemic Neuromorphology, The Nencki Institute of Experimental Biology, 02–093, Warsaw, ul. Pasteura 3, Poland
| | - Joanna Dzwonek
- Laboratory of Molecular and Systemic Neuromorphology, The Nencki Institute of Experimental Biology, 02–093, Warsaw, ul. Pasteura 3, Poland
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23
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Butzlaff M, Weigel A, Ponimaskin E, Zeug A. eSIP: A Novel Solution-Based Sectioned Image Property Approach for Microscope Calibration. PLoS One 2015; 10:e0134980. [PMID: 26244982 PMCID: PMC4526552 DOI: 10.1371/journal.pone.0134980] [Citation(s) in RCA: 9] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 07/15/2015] [Indexed: 11/20/2022] Open
Abstract
Fluorescence confocal microscopy represents one of the central tools in modern sciences. Correspondingly, a growing amount of research relies on the development of novel microscopic methods. During the last decade numerous microscopic approaches were developed for the investigation of various scientific questions. Thereby, the former qualitative imaging methods became replaced by advanced quantitative methods to gain more and more information from a given sample. However, modern microscope systems being as complex as they are, require very precise and appropriate calibration routines, in particular when quantitative measurements should be compared over longer time scales or between different setups. Multispectral beads with sub-resolution size are often used to describe the point spread function and thus the optical properties of the microscope. More recently, a fluorescent layer was utilized to describe the axial profile for each pixel, which allows a spatially resolved characterization. However, fabrication of a thin fluorescent layer with matching refractive index is technically not solved yet. Therefore, we propose a novel type of calibration concept for sectioned image property (SIP) measurements which is based on fluorescent solution and makes the calibration concept available for a broader number of users. Compared to the previous approach, additional information can be obtained by application of this extended SIP chart approach, including penetration depth, detected number of photons, and illumination profile shape. Furthermore, due to the fit of the complete profile, our method is less susceptible to noise. Generally, the extended SIP approach represents a simple and highly reproducible method, allowing setup independent calibration and alignment procedures, which is mandatory for advanced quantitative microscopy.
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Affiliation(s)
- Malte Butzlaff
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
| | - Arwed Weigel
- Carl Zeiss Microscopy GmbH, Kistlerhofstr. 75, München, Germany
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Center of Physiology, Hannover Medical School, Hannover, Germany
- * E-mail:
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24
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Tian Q, Schröder L, Flockerzi A, Zeug A, Kaestner L, Lipp P. Large-Scale, Automated Calcium Spark Analysis using iSpark Reveals Functional and Spatial Remodeling During Cardiac Hypertrophy. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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25
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Bang C, Batkai S, Dangwal S, Gupta SK, Foinquinos A, Holzmann A, Just A, Remke J, Zimmer K, Zeug A, Ponimaskin E, Schmiedl A, Yin X, Mayr M, Halder R, Fischer A, Engelhardt S, Wei Y, Schober A, Fiedler J, Thum T. Cardiac fibroblast-derived microRNA passenger strand-enriched exosomes mediate cardiomyocyte hypertrophy. J Clin Invest 2014; 124:2136-46. [PMID: 24743145 DOI: 10.1172/jci70577] [Citation(s) in RCA: 737] [Impact Index Per Article: 73.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 02/20/2014] [Indexed: 12/20/2022] Open
Abstract
In response to stress, the heart undergoes extensive cardiac remodeling that results in cardiac fibrosis and pathological growth of cardiomyocytes (hypertrophy), which contribute to heart failure. Alterations in microRNA (miRNA) levels are associated with dysfunctional gene expression profiles associated with many cardiovascular disease conditions; however, miRNAs have emerged recently as paracrine signaling mediators. Thus, we investigated a potential paracrine miRNA crosstalk between cardiac fibroblasts and cardiomyocytes and found that cardiac fibroblasts secrete miRNA-enriched exosomes. Surprisingly, evaluation of the miRNA content of cardiac fibroblast-derived exosomes revealed a relatively high abundance of many miRNA passenger strands ("star" miRNAs), which normally undergo intracellular degradation. Using confocal imaging and coculture assays, we identified fibroblast exosomal-derived miR-21_3p (miR-21*) as a potent paracrine-acting RNA molecule that induces cardiomyocyte hypertrophy. Proteome profiling identified sorbin and SH3 domain-containing protein 2 (SORBS2) and PDZ and LIM domain 5 (PDLIM5) as miR-21* targets, and silencing SORBS2 or PDLIM5 in cardiomyocytes induced hypertrophy. Pharmacological inhibition of miR-21* in a mouse model of Ang II-induced cardiac hypertrophy attenuated pathology. These findings demonstrate that cardiac fibroblasts secrete star miRNA-enriched exosomes and identify fibroblast-derived miR-21* as a paracrine signaling mediator of cardiomyocyte hypertrophy that has potential as a therapeutic target.
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26
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Zeug A, Stawarski M, Bieganska K, Korotchenko S, Wlodarczyk J, Dityatev A, Ponimaskin E. Current microscopic methods for the neural ECM analysis. Prog Brain Res 2014; 214:287-312. [PMID: 25410363 DOI: 10.1016/b978-0-444-63486-3.00013-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The extracellular matrix (ECM) occupies the space between both neurons and glial cells and thus provides a microenvironment that regulates multiple aspects of neural activities. Because of the vital role of ECM as a natural environment of cells in vivo, there is a growing interest to develop methodology allowing for the detailed structural and functional analyses of ECM. In this chapter, we provide the detailed overview of current microscopic methods used for ECM analysis and also describe general labeling strategies for ECM visualization. Since ECM remodeling involves the proteolytic cleavage of ECM, we will also describe current experimental approaches to image the proteolytic reorganization and/or degradation of ECM. The special focus of this chapter is set to the application of Förster resonance energy transfer-based approaches to monitor intracellular and extracellular matrix functions with high spatiotemporal resolution.
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Affiliation(s)
- Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Michal Stawarski
- Laboratory of Cell Biophysics, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | - Svetlana Korotchenko
- Laboratory for Brain Extracellular Matrix Research, University of Nizhny Novgorod, Nizhny Novgorod, Russia; Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy; Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy
| | - Jakub Wlodarczyk
- Laboratory of Cell Biophysics, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Alexander Dityatev
- Laboratory for Brain Extracellular Matrix Research, University of Nizhny Novgorod, Nizhny Novgorod, Russia; Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy; Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy; Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Magdeburg, Germany
| | - Evgeni Ponimaskin
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany.
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Gorinski N, Kowalsman N, Renner U, Wirth A, Reinartz MT, Seifert R, Zeug A, Ponimaskin E, Niv MY. Computational and experimental analysis of the transmembrane domain 4/5 dimerization interface of the serotonin 5-HT(1A) receptor. Mol Pharmacol 2012; 82:448-63. [PMID: 22669805 DOI: 10.1124/mol.112.079137] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Experimental evidence suggests that most members of class A G-protein coupled receptors (GPCRs) can form homomers and heteromers in addition to functioning as single monomers. In particular, serotonin (5-HT) receptors were shown to homodimerize and heterodimerize with other GPCRs, although the details and the physiological role of the oligomerization has not yet been fully elucidated. Here we used computational modeling of the 5-HT(1A) receptor monomer and dimer to predict residues important for dimerization. Based on these results, we carried out rationally designed site-directed mutagenesis. The ability of the mutants to dimerize was evaluated using different FRET-based approaches. The reduced levels of acceptor photobleaching-Förster resonance energy transfer (FRET) and the lower number of monomers participating in oligomers, as assessed by lux-FRET, confirmed the decreased ability of the mutants to dimerize and the involvement of the predicted contacts (Trp175(4.64), Tyr198(5.41), Arg151(4.40), and Arg152(4.41)) at the interface. This information was reintroduced as constraints for computational protein-protein docking to obtain a high-quality dimer model. Analysis of the refined model as well as molecular dynamics simulations of wild-type (WT) and mutant dimers revealed compensating interactions in dimers composed of WT and W175A mutant. This provides an explanation for the requirement of mutations of Trp175(4.64) in both homomers for disrupting dimerization. Our iterative computational-experimental study demonstrates that transmembrane domains TM4/TM5 can form an interaction interface in 5-HT(1A) receptor dimers and indicates that specific amino acid interactions maintain this interface. The mutants and the optimized model of the dimer structure may be used in functional studies of serotonin dimers.
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Zeug A, Meyer M, Lo PC, Ng DKP, Röder B. Fluorescence anisotropy and transient absorption of halogenated silicon(IV) phthalocyanines with axial poly(ethylene-glycol) substituents. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424605000381] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Herein we report the utilization of fluorescence anisotropy to give rough hints on the conformation of three halogenated silicon-phthalocyanines with axially substituted polyethyleneglycol chains in solution. To deconvolute decay data sets from the instrumental response function a scanning fit algorithm was used, which facilitates the visualization of fitting accuracy and correlation of parameters of the assumed decay function. Moreover, to extend our investigation of photophysical properties in the nonlinear domain, the transient absorption in the picosecond range was measured and thus excited state absorption spectra are presented.
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Affiliation(s)
- Andre Zeug
- Humboldt-Universität Berlin, Institut für Physik, Photobiophysik, Newtonstr. 15, 12489 Berlin, Germany
| | - Matthias Meyer
- Humboldt-Universität Berlin, Institut für Physik, Photobiophysik, Newtonstr. 15, 12489 Berlin, Germany
| | - Pui-Chi Lo
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Dennis K. P. Ng
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Beate Röder
- Humboldt-Universität Berlin, Institut für Physik, Photobiophysik, Newtonstr. 15, 12489 Berlin, Germany
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Renner U, Zeug A, Woehler A, Niebert M, Dityatev A, Dityateva G, Gorinski N, Guseva D, Abdel-Galil D, Fröhlich M, Döring F, Wischmeyer E, Richter DW, Neher E, Ponimaskin EG. Heterodimerization of serotonin receptors 5-HT1A and 5-HT7 differentially regulates receptor signalling and trafficking. J Cell Sci 2012; 125:2486-99. [DOI: 10.1242/jcs.101337] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Serotonin receptors 5-HT1A and 5-HT7 are highly co-expressed in brain regions implicated in depression. However, their functional interaction has not been established. In the present study we show that 5-HT1A and 5-HT7 receptors form heterodimers both in vitro and in vivo. Foerster resonance energy transfer-based assays revealed that, in addition to heterodimers, homodimers composed either by 5-HT1A or 5-HT7 receptors together with monomers co-exist in cells. The highest affinity to form the complex was obtained for the 5-HT7-5-HT7 homodimers, followed by the 5-HT7-5-HT1A heterodimers and 5-HT1A-5-HT1A homodimers. Functionally, heterodimerization decreases 5-HT1A receptor-mediated activation of Gi-protein without affecting 5-HT7 receptor-mediated signalling. Moreover, heterodimerization markedly decreases the ability of the 5-HT1A receptor to activate G-protein gated inwardly rectifying potassium channels in a heterologous system. The inhibitory effect on such channels was also preserved in hippocampal neurons, demonstrating a physiological relevance of heteromerization in vivo. In addition, heterodimerization is critically involved in initiation of the serotonin-mediated 5-HT1A receptor internalization and also enhances the ability of the 5-HT1A receptor to activate the mitogen-activated protein kinases. Finally, we found that production of 5-HT7 receptors in hippocampus continuously decreases during postnatal development, indicating that the relative concentration of 5-HT1A-5-HT7 heterodimers and, consequently, their functional importance undergoes pronounced developmental changes.
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Nölle A, Zeug A, van Bergeijk J, Tönges L, Gerhard R, Brinkmann H, Al Rayes S, Hensel N, Schill Y, Apkhazava D, Jablonka S, O'mer J, Srivastav RK, Baasner A, Lingor P, Wirth B, Ponimaskin E, Niedenthal R, Grothe C, Claus P. The spinal muscular atrophy disease protein SMN is linked to the Rho-kinase pathway via profilin. Hum Mol Genet 2011; 20:4865-78. [PMID: 21920940 DOI: 10.1093/hmg/ddr425] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinal muscular atrophy (SMA), a frequent neurodegenerative disease, is caused by reduced levels of functional survival of motoneuron (SMN) protein. SMN is involved in multiple pathways, including RNA metabolism and splicing as well as motoneuron development and function. Here we provide evidence for a major contribution of the Rho-kinase (ROCK) pathway in SMA pathogenesis. Using an in vivo protein interaction system based on SUMOylation of proteins, we found that SMN is directly interacting with profilin2a. Profilin2a binds to a stretch of proline residues in SMN, which is heavily impaired by a novel SMN2 missense mutation (S230L) derived from a SMA patient. In different SMA models, we identified differential phosphorylation of the ROCK-downstream targets cofilin, myosin-light chain phosphatase and profilin2a. We suggest that hyper-phosphorylation of profilin2a is the molecular link between SMN and the ROCK pathway repressing neurite outgrowth in neuronal cells. Finally, we found a neuron-specific increase in the F-/G-actin ratio that further support the role of actin dynamics in SMA pathogenesis.
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Affiliation(s)
- Anna Nölle
- Institute for Neuroanatomy, Hannover Medical School, Hannover 30623, Germany
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Keil VC, Funke F, Zeug A, Schild D, Müller M. Ratiometric high-resolution imaging of JC-1 fluorescence reveals the subcellular heterogeneity of astrocytic mitochondria. Pflugers Arch 2011; 462:693-708. [PMID: 21881871 PMCID: PMC3192276 DOI: 10.1007/s00424-011-1012-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [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: 08/01/2011] [Accepted: 08/07/2011] [Indexed: 11/25/2022]
Abstract
Using the mitochondrial potential (ΔΨm) marker JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide) and high-resolution imaging, we functionally analyzed mitochondria in cultured rat hippocampal astrocytes. Ratiometric detection of JC-1 fluorescence identified mitochondria with high and low ΔΨm. Mitochondrial density was highest in the perinuclear region, whereas ΔΨm tended to be higher in peripheral mitochondria. Spontaneous ΔΨm fluctuations, representing episodes of increased energization, appeared in individual mitochondria or synchronized in mitochondrial clusters. They continued upon withdrawal of extracellular Ca2+, but were antagonized by dantrolene or 2-aminoethoxydiphenylborate (2-APB). Fluo-3 imaging revealed local cytosolic Ca2+ transients with similar kinetics that also were depressed by dantrolene and 2-APB. Massive cellular Ca2+ load or metabolic impairment abolished ΔΨm fluctuations, occasionally evoking heterogeneous mitochondrial depolarizations. The detected diversity and ΔΨm heterogeneity of mitochondria confirms that even in less structurally polarized cells, such as astrocytes, specialized mitochondrial subpopulations coexist. We conclude that ΔΨm fluctuations are an indication of mitochondrial viability and are triggered by local Ca2+ release from the endoplasmic reticulum. This spatially confined organelle crosstalk contributes to the functional heterogeneity of mitochondria and may serve to adapt the metabolism of glial cells to the activity and metabolic demand of complex neuronal networks. The established ratiometric JC-1 imaging—especially combined with two-photon microscopy—enables quantitative functional analyses of individual mitochondria as well as the comparison of mitochondrial heterogeneity in different preparations and/or treatment conditions.
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Affiliation(s)
- Vera C Keil
- DFG Research Center Molecular Physiology of the Brain, Humboldtallee 23, D-37073, Göttingen, Germany
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Miranda-Laferte E, Gonzalez-Gutierrez G, Schmidt S, Zeug A, Ponimaskin EG, Neely A, Hidalgo P. Homodimerization of the Src homology 3 domain of the calcium channel β-subunit drives dynamin-dependent endocytosis. J Biol Chem 2011; 286:22203-10. [PMID: 21502319 DOI: 10.1074/jbc.m110.201871] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Voltage-dependent calcium channels constitute the main entry pathway for calcium into excitable cells. They are heteromultimers formed by an α(1) pore-forming subunit (Ca(V)α(1)) and accessory subunits. To achieve a precise coordination of calcium signals, the expression and activity of these channels is tightly controlled. The accessory β-subunit (Ca(V)β), a membrane associated guanylate kinase containing one guanylate kinase (β-GK) and one Src homology 3 (β-SH3) domain, has antagonistic effects on calcium currents by regulating different aspects of channel function. Although β-GK binds to a conserved site within the α(1)-pore-forming subunit and facilitates channel opening, β-SH3 binds to dynamin and promotes endocytosis. Here, we investigated the molecular switch underlying the functional duality of this modular protein. We show that β-SH3 homodimerizes through a single disulfide bond. Substitution of the only cysteine residue abolishes dimerization and impairs internalization of L-type Ca(V)1.2 channels expressed in Xenopus oocytes while preserving dynamin binding. Covalent linkage of the β-SH3 dimerization-deficient mutant yields a concatamer that binds to dynamin and restores endocytosis. Moreover, using FRET analysis, we show in living cells that Ca(V)β form oligomers and that this interaction is reduced by Ca(V)α(1). Association of Ca(V)β with a polypeptide encoding the binding motif in Ca(V)α(1) inhibited endocytosis. Together, these findings reveal that β-SH3 dimerization is crucial for endocytosis and suggest that channel activation and internalization are two mutually exclusive functions of Ca(V)β. We propose that a change in the oligomeric state of Ca(V)β is the functional switch between channel activator and channel internalizer.
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Affiliation(s)
- Erick Miranda-Laferte
- Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
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Salonikidis PS, Niebert M, Ullrich T, Bao G, Zeug A, Richter DW. An ion-insensitive cAMP biosensor for long term quantitative ratiometric fluorescence resonance energy transfer (FRET) measurements under variable physiological conditions. J Biol Chem 2011; 286:23419-31. [PMID: 21454618 DOI: 10.1074/jbc.m111.236869] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ratiometric measurements with FRET-based biosensors in living cells using a single fluorescence excitation wavelength are often affected by a significant ion sensitivity and the aggregation behavior of the FRET pair. This is an important problem for quantitative approaches. Here we report on the influence of physiological ion concentration changes on quantitative ratiometric measurements by comparing different FRET pairs for a cAMP-detecting biosensor. We exchanged the enhanced CFP/enhanced YFP FRET pair of an established Epac1-based biosensor by the fluorophores mCerulean/mCitrine. In the case of enhanced CFP/enhanced YFP, we showed that changes in proton, and (to a lesser extent) chloride ion concentrations result in incorrect ratiometric FRET signals, which may exceed the dynamic range of the biosensor. Calcium ions have no direct, but an indirect pH-driven effect by mobilizing protons. These ion dependences were greatly eliminated when mCerulean/mCitrine fluorophores were used. For such advanced FRET pairs the biosensor is less sensitive to changes in ion concentration and allows consistent cAMP concentration measurements under different physiological conditions, as occur in metabolically active cells. In addition, we verified that the described FRET pair exchange increased the dynamic range of the FRET efficiency response. The time window for stable experimental conditions was also prolonged by a faster biosensor expression rate in transfected cells and a greatly reduced tendency to aggregate, which reduces cytotoxicity. These properties were verified in functional tests in single cells co-expressing the biosensor and the 5-HT(1A) receptor.
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Affiliation(s)
- Petrus S Salonikidis
- Department of Neuro- and Sensory Physiology, University of Göttingen, 37073 Göttingen, Germany.
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Ribes S, Ebert S, Regen T, Czesnik D, Scheffel J, Zeug A, Bunkowski S, Eiffert H, Hanisch UK, Hammerschmidt S, Nau R. Fibronectin stimulates Escherichia coli phagocytosis by microglial cells. Glia 2010; 58:367-76. [PMID: 19780198 DOI: 10.1002/glia.20929] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Microglia express Toll-like receptors (TLRs) that recognize invading pathogens as well as endogenous proteins such as fibronectin under nonphysiological conditions. Here, we demonstrated that fibronectin stimulates murine microglia in culture in a dose-dependent manner: microglial cells secreted proinflammatory cytokines and chemokines and increased phagocytosis of Escherichia coli DH5alpha and E. coli K1 strains. Low levels of fibronectin exerted a synergistic effect on the release of proinflammatory compounds by microglia co-stimulated with agonists for TLR1/2 (Pam(3)CSK(4)) or TLR9 (CpG DNA), but not in combination with the TLR4 agonist lipopolysaccharide (LPS). Phagocytosis of bacterial strains was moderately enhanced when microglia was co-stimulated with high concentrations of fibronectin and one pathogen-derived TLR agonist. In conclusion, fibronectin increased proinflammatory and phagocytotic functions in microglia and partially synergized with microbial TLR agonists.
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Affiliation(s)
- Sandra Ribes
- Department of Neurology, University of Göttingen, Robert-Koch-Strasse 40, Göttingen, Germany.
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Singh AK, Moros EG, Novak P, Straube W, Zeug A, Locke JE, Myerson RJ. MicroPET-compatible, small animal hyperthermia ultrasound system (SAHUS) for sustainable, collimated and controlled hyperthermia of subcutaneously implanted tumours. Int J Hyperthermia 2009; 20:32-44. [PMID: 14612312 DOI: 10.1080/02656730310001609326] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [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] [Indexed: 10/26/2022] Open
Abstract
An external ultrasound system was developed for the heating of subcutaneously implanted tumours in small animals. This small animal hyperthermia ultrasound system (SAHUS) was designed to be compatible with a microPET (small animal positron emission tomography) scanner to facilitate studies of hyperthermia effects on tumour hypoxia. Collimation and localization of energy deposition, a specific goal for the new device to avoid regional and/or systemic heating of small animals, was demonstrated using thermoradiography following high-power short-time heating of a layered gel phantom. The in vivo heating capabilities of the SAHUS were tested using PC3 cell line tumours (2000-2700 mm(3)) grown in the lateral proximal thighs of Nu-/Nu- nuBR nude mice. Intratumour temperatures were recorded during heating trials with deep and superficial interstitial thermocouples. The experimental data showed that the SAHUS could produce hyperthermia in 8 +/- 2 mm diameter tumours in small animals to a target temperature of 41.5 degrees C and maintain it within a narrow temperature range (+/- 0.3 degrees C) for up to 4 h without raising the core temperature of the animals. PET imaging studies, data to be published separately, were conducted before and during SAHUS-induced hyperthermia. Both devices performed as expected and there was no significant decrease in image quality. In this paper, the new SAHUS is described and data from phantom and in vivo experiments presented.
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Affiliation(s)
- A K Singh
- Washington University School of Medicine, Department of Radiation Oncology, St. Louis, MO 63108, USA
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Lipp P, Hammer KP, Flockerzi A, Zeug A, Kaestner L. Automatic Calcium Spark Detection and Analysis in Time Series of Two-Dimensional Confocal Images. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.1375] [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: 11/25/2022] Open
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Kobe F, Renner U, Woehler A, Wlodarczyk J, Papusheva E, Bao G, Zeug A, Richter DW, Neher E, Ponimaskin E. Stimulation- and palmitoylation-dependent changes in oligomeric conformation of serotonin 5-HT1A receptorsi. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2008; 1783:1503-16. [DOI: 10.1016/j.bbamcr.2008.02.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 02/21/2008] [Accepted: 02/25/2008] [Indexed: 12/01/2022]
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Heine M, Voyno-Yasenetskaya T, Zeug A, Ponimaskin E, Salonikidis P. Monitoring Receptor- Mediated Changes of Intracellular cAMP Level by Using Ion Channels and Fluorescent Proteins as Biosensors. Front Neurosci 2007. [DOI: 10.1201/9781420005752.ch2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Novák P, Moros EG, Parry JJ, Rogers BE, Myerson RJ, Zeug A, Locke JE, Rossin R, Straube WL, Singh AK. Experience with a small animal hyperthermia ultrasound system (SAHUS): report on 83 tumours. Phys Med Biol 2005; 50:5127-39. [PMID: 16237245 DOI: 10.1088/0031-9155/50/21/012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [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] [Indexed: 11/11/2022]
Abstract
An external local ultrasound (US) system was developed to induce controlled hyperthermia of subcutaneously implanted tumours in small animals (e.g., mice and rats). It was designed to be compatible with a small animal positron emission tomography scanner (microPET) to facilitate studies of hyperthermia-induced tumour re-oxygenation using a PET radiopharmaceutical, but it is applicable for any small animal study requiring controlled heating. The system consists of an acrylic applicator bed with up to four independent 5 MHz planar disc US transducers of 1 cm in diameter, a four-channel radiofrequency (RF) generator, a multiple thermocouple thermometry unit, and a personal computer with custom monitoring and controlling software. Although the system presented here was developed to target tumours of up to 1 cm in diameter, the applicator design allows for different piezoelectric transducers to be exchanged and operated within the 3.5-6.5 MHz band to target different tumour sizes. Temperature feedback control software was developed on the basis of a proportional-integral-derivative (PID) approach when the measured temperatures were within a selectable temperature band about the target temperature. Outside this band, an on/off control action was applied. Perfused tissue-mimicking phantom experiments were performed to determine optimum controller gain constants, which were later employed successfully in animal experiments. The performance of the SAHUS (small animal hyperthermia ultrasound system) was tested using several tumour types grown in thighs of female nude (nu/nu) mice. To date, the system has successfully treated 83 tumours to target temperatures in the range of 41-43 degrees C for periods of 65 min on average.
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Affiliation(s)
- P Novák
- Department of Radiation Oncology, Washington University School of Medicine, 4511 Forest Park Ave., Suite 200, St Louis, MO 63108, USA
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Locke J, Zeug A, Thompson D, Allan J, Mazzarella K, Novak P, Hanson D, Singh AK, Moros EG, Pandita TK. Localized versus regional hyperthermia: comparison of xenotransplants treated with a small animal ultrasound system and waterbath limb immersion. Int J Hyperthermia 2005; 21:271-81. [PMID: 16019853 DOI: 10.1080/02656730500070151] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The response of xenotransplants were compared with waterbath immersion vs focal ultrasound (US) hyperthermia using tumour growth delay, immunhistochemistry and histopathology assays. Waterbath hyperthermia was performed by limb immersion. Precautions were taken to minimize total body heating by surrounding the mouse with plastic insulators. Thermometry was performed with clinical-grade, 20-gauge needle thermocouples and monitored with a Labthermics unit. Significant differences in cytotoxicity between ultrasound and waterbath treatment of tumors at 43 degrees C were observed as determined by TUNNEL assay. Conversely, contralateral (non-treated) tumours in animals treated with similar temperature demonstrated no significant differences between modalities. Western blot analysis revealed increased hsp70 induction at 43 degrees C in waterbath vs focal ultrasound hyperthermia. Comparison of tumour growth delay between tumours heated with waterbath vs ultrasound at 43 degrees C but not at 41 degrees C revealed significant differences. This is the first study comparing localized vs regional hyperthermia using the small animal ultrasound system (SAHUS) delivery system. Consistent ultrasound hyperthermia can be achieved throughout a xenotransplant. At equivalent temperature of 43 degrees C for 60?min, waterbath hyperthermia demonstrated greater local response vs ultrasound hyperthermia.
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Affiliation(s)
- J Locke
- Department of Radiation Oncology, Washington University School of Medicine, Saint Louis, MO 63108, USA
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Thompson N, Zeug A, Allan J, Locke J. Waterbath versus ultrasound hyperthermia in vivo: Implications for clinical hyperthermia. Int J Radiat Oncol Biol Phys 2004. [DOI: 10.1016/j.ijrobp.2004.07.215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Chen Y, Hanack M, O'Flaherty S, Bernd G, Zeug A, Roeder B, Blau WJ. An Axially Grafted Charm Bracelet Type Indium Phthalocyanine Copolymer. Macromolecules 2003. [DOI: 10.1021/ma025939e] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yu Chen
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
| | - Michael Hanack
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
| | - Sean O'Flaherty
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
| | - Goelach Bernd
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
| | - Andre Zeug
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
| | - Beate Roeder
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
| | - Werner J. Blau
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, Washington 98195-2120; Institut für Organische Chemie, Organische Chemie II, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany; Materials Ireland Polymer Research Centre, Department of Physics, Trinity College, University of Dublin, Dublin 2, Ireland; and Humboldt Universitaet, Institut fuer Physik, Lehrstuhl Photobiophys, Invalidenstrasse 110, D-10115, Berlin, Germany
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Lo PC, Wang S, Zeug A, Meyer M, Röder B, Ng DK. Preparation and photophysical properties of halogenated silicon(IV) phthalocyanines substituted axially with poly(ethylene glycol) chains. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(03)00061-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Zimmermann J, Zeug A, Röder B. A generalization of the Jablonski diagram to account for polarization and anisotropy effects in time-resolved experiments. Phys Chem Chem Phys 2003. [DOI: 10.1039/b303138a] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zeug A, Paul A, Röder B. Observation of the phase transition in phospholipid liposomes taking advantage of the particular optical properties of octa‐α‐butyloxy‐H2phthalocyanines. J PORPHYR PHTHALOCYA 2001. [DOI: 10.1002/jpp.374.abs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zeug A, Rückmann I, Röder B. Picosecond transient dichroism and birefringence spectroscopy on pheophorbide-a molecules in solution. ACTA ACUST UNITED AC 2001. [DOI: 10.1088/1464-4266/3/2/377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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RuUckmann I, Zeug A, Herter R, Roder B. On the Influence of Higher Excited States on the ISC Quantum Yield of Octa-aL-alkyloxy-substituted Zn-Phthalocyanine Molecules Studied by Nonlinear Absorption. Photochem Photobiol 1997. [DOI: 10.1111/j.1751-1097.1997.tb03192.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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