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Eitelmann S, Everaerts K, Petersilie L, Rose CR, Stephan J. Ca 2+-dependent rapid uncoupling of astrocytes upon brief metabolic stress. Front Cell Neurosci 2023; 17:1151608. [PMID: 37886111 PMCID: PMC10598858 DOI: 10.3389/fncel.2023.1151608] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 08/23/2023] [Indexed: 10/28/2023] Open
Abstract
Astrocytic gap junctional coupling is a major element in neuron-glia interaction. There is strong evidence that impaired coupling is involved in neurological disorders. Reduced coupling was, e.g., demonstrated for core regions of ischemic stroke that suffer from massive cell death. In the surrounding penumbra, cells may recover, but recovery is hampered by spreading depolarizations, which impose additional metabolic stress onto the tissue. Spreading depolarizations are characterized by transient breakdown of cellular ion homeostasis, including pH and Ca2+, which might directly affect gap junctional coupling. Here, we exposed acute mouse neocortical tissue slices to brief metabolic stress and examined its effects on the coupling strength between astrocytes. Changes in gap junctional coupling were assessed by recordings of the syncytial isopotentiality. Moreover, quantitative ion imaging was performed in astrocytes to analyze the mechanisms triggering the observed changes. Our experiments show that a 2-minute perfusion of tissue slices with blockers of glycolysis and oxidative phosphorylation causes a rapid uncoupling in half of the recorded cells. They further indicate that uncoupling is not mediated by the accompanying (moderate) intracellular acidification. Dampening large astrocytic Ca2+ loads by removal of extracellular Ca2+ or blocking Ca2+ influx pathways as well as a pharmacological inhibition of calmodulin, however, prevent the uncoupling. Taken together, we conclude that astrocytes exposed to brief episodes of metabolic stress can undergo a rapid, Ca2+/calmodulin-dependent uncoupling. Such uncoupling may help to confine and reduce cellular damage in the ischemic penumbra in vivo.
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Affiliation(s)
| | | | | | - Christine R. Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Jonathan Stephan
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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2
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Westerlund AM, Sridhar A, Dahl L, Andersson A, Bodnar AY, Delemotte L. Markov state modelling reveals heterogeneous drug-inhibition mechanism of Calmodulin. PLoS Comput Biol 2022; 18:e1010583. [PMID: 36206305 PMCID: PMC9581412 DOI: 10.1371/journal.pcbi.1010583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 10/19/2022] [Accepted: 09/18/2022] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) is a calcium sensor which binds and regulates a wide range of target-proteins. This implicitly enables the concentration of calcium to influence many downstream physiological responses, including muscle contraction, learning and depression. The antipsychotic drug trifluoperazine (TFP) is a known CaM inhibitor. By binding to various sites, TFP prevents CaM from associating to target-proteins. However, the molecular and state-dependent mechanisms behind CaM inhibition by drugs such as TFP are largely unknown. Here, we build a Markov state model (MSM) from adaptively sampled molecular dynamics simulations and reveal the structural and dynamical features behind the inhibitory mechanism of TFP-binding to the C-terminal domain of CaM. We specifically identify three major TFP binding-modes from the MSM macrostates, and distinguish their effect on CaM conformation by using a systematic analysis protocol based on biophysical descriptors and tools from machine learning. The results show that depending on the binding orientation, TFP effectively stabilizes features of the calcium-unbound CaM, either affecting the CaM hydrophobic binding pocket, the calcium binding sites or the secondary structure content in the bound domain. The conclusions drawn from this work may in the future serve to formulate a complete model of pharmacological modulation of CaM, which furthers our understanding of how these drugs affect signaling pathways as well as associated diseases. Calmodulin (CaM) is a calcium-sensing protein which makes other proteins dependent on the surrounding calcium concentration by binding to these proteins. Such protein-protein interactions with CaM are vital for calcium to control many physiological pathways within the cell. The antipsychotic drug trifluoperazine (TFP) inhibits CaM’s ability to bind and regulate other proteins. Here, we use molecular dynamics simulations together with Markov state modeling and machine learning to understand the structural and dynamical features by which TFP bound to the one domain of CaM prevents association to other proteins. We find that TFP encourages CaM to adopt a conformation that is like the one stabilized in absence of calcium: depending on the binding orientation of TFP, the drug indeed either affects the CaM hydrophobic binding pocket, the calcium binding sites or the secondary structure content in the domain. Understanding TFP binding is a first step towards designing better drugs targeting CaM.
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Affiliation(s)
- Annie M. Westerlund
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Akshay Sridhar
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Leo Dahl
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Alma Andersson
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
- Division of Gene Technology, Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Anna-Yaroslava Bodnar
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Lucie Delemotte
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
- * E-mail:
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3
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Mahmud Z, Tikunova S, Belevych N, Wagg CS, Zhabyeyev P, Liu PB, Rasicci DV, Yengo CM, Oudit GY, Lopaschuk GD, Reiser PJ, Davis JP, Hwang PM. Small Molecule RPI-194 Stabilizes Activated Troponin to Increase the Calcium Sensitivity of Striated Muscle Contraction. Front Physiol 2022; 13:892979. [PMID: 35755445 PMCID: PMC9213791 DOI: 10.3389/fphys.2022.892979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
Small molecule cardiac troponin activators could potentially enhance cardiac muscle contraction in the treatment of systolic heart failure. We designed a small molecule, RPI-194, to bind cardiac/slow skeletal muscle troponin (Cardiac muscle and slow skeletal muscle share a common isoform of the troponin C subunit.) Using solution NMR and stopped flow fluorescence spectroscopy, we determined that RPI-194 binds to cardiac troponin with a dissociation constant KD of 6-24 μM, stabilizing the activated complex between troponin C and the switch region of troponin I. The interaction between RPI-194 and troponin C is weak (KD 311 μM) in the absence of the switch region. RPI-194 acts as a calcium sensitizer, shifting the pCa50 of isometric contraction from 6.28 to 6.99 in mouse slow skeletal muscle fibers and from 5.68 to 5.96 in skinned cardiac trabeculae at 100 μM concentration. There is also some cross-reactivity with fast skeletal muscle fibers (pCa50 increases from 6.27 to 6.52). In the slack test performed on the same skinned skeletal muscle fibers, RPI-194 slowed the velocity of unloaded shortening at saturating calcium concentrations, suggesting that it slows the rate of actin-myosin cross-bridge cycling under these conditions. However, RPI-194 had no effect on the ATPase activity of purified actin-myosin. In isolated unloaded mouse cardiomyocytes, RPI-194 markedly decreased the velocity and amplitude of contractions. In contrast, cardiac function was preserved in mouse isolated perfused working hearts. In summary, the novel troponin activator RPI-194 acts as a calcium sensitizer in all striated muscle types. Surprisingly, it also slows the velocity of unloaded contraction, but the cause and significance of this is uncertain at this time. RPI-194 represents a new class of non-specific troponin activator that could potentially be used either to enhance cardiac muscle contractility in the setting of systolic heart failure or to enhance skeletal muscle contraction in neuromuscular disorders.
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Affiliation(s)
- Zabed Mahmud
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Svetlana Tikunova
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States
| | - Natalya Belevych
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, United States
| | - Cory S Wagg
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Pavel Zhabyeyev
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Philip B Liu
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - David V Rasicci
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, University Park, PA, United States
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, University Park, PA, United States
| | - Gavin Y Oudit
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Gary D Lopaschuk
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Peter J Reiser
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, United States
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States
| | - Peter M Hwang
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.,Department of Medicine, University of Alberta, Edmonton, AB, Canada
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4
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Melnitskaya AV, Krutetskaya ZI, Antonov VG, Krutetskaya NI. The Sigma-1 Receptor Ligands Chlorpromazine and Trifluoperazine Inhibit Na+ Transport in Frog Skin Epithelium. Biophysics (Nagoya-shi) 2020. [DOI: 10.1134/s0006350920050115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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5
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Kang S, Kwon HN, Kang S, Park S. Interaction between IDH1 WT and calmodulin and its implications for glioblastoma cell growth and migration. Biochem Biophys Res Commun 2020; 524:224-230. [PMID: 31983428 DOI: 10.1016/j.bbrc.2020.01.073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 01/14/2020] [Indexed: 01/02/2023]
Abstract
Isocitrate dehydrogenase (IDH) mutations are found in low-grade gliomas, and the product of the IDH mutant (MT), 2-hydroxyglutarate (2-HG), is the first known oncometabolite. However, the roles of the IDH wild type (WT) in high-grade glioblastoma, which rarely has the IDH mutation, are still unknown. To investigate possible pathways related to IDH WT in gliomas, we carried out bioinformatics analysis, and found that IDH1 has several putative calmodulin (CaM) binding sites. Pull-down and quantitative dissociation constant (Kd) measurements using recombinant proteins showed that IDH1 WT indeed binds to CaM with a higher affinity than IDH1 R132H MT. This biochemical interaction was demonstrated also in the cellular environment by immunoprecipitation with glioblastoma cell extracts. A synthetic peptide for the suggested binding region interfered with the interaction between CaM and IDH1, confirming the specificity of the binding. Direct binding between the synthetic peptide and CaM was observed in an NMR binding experiment, which additionally revealed that the peptide initially binds to the C-lobe of CaM. The physiological meaning of the CaM-IDH1 WT binding was shown with trifluoperazine (TFP), a CaM antagonist, which disrupted the binding and inhibited survival and migration of glioblastoma cells with IDH1 WT. As CaM signaling is activated in glioblastoma, our results suggest that IDH1 WT may be involved in the CaM-signaling pathway in the tumorigenesis of high-grade gliomas.
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Affiliation(s)
- Sunmi Kang
- Natural Product Research Institute, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea.
| | - Hyuk Nam Kwon
- Natural Product Research Institute, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea; Stem Cells and Metabolism Research Program, Faculty of Medicine / Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Soeun Kang
- Natural Product Research Institute, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea; Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Sunghyouk Park
- Natural Product Research Institute, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea.
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The KN-93 Molecule Inhibits Calcium/Calmodulin-Dependent Protein Kinase II (CaMKII) Activity by Binding to Ca 2+/CaM. J Mol Biol 2019; 431:1440-1459. [PMID: 30753871 DOI: 10.1016/j.jmb.2019.02.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 12/14/2018] [Accepted: 02/04/2019] [Indexed: 12/22/2022]
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional serine/threonine protein kinase that transmits calcium signals in various cellular processes. CaMKII is activated by calcium-bound calmodulin (Ca2+/CaM) through a direct binding mechanism involving a regulatory C-terminal α-helix in CaMKII. The Ca2+/CaM binding triggers transphosphorylation of critical threonine residues proximal to the CaM-binding site leading to the autoactivated state of CaMKII. The demonstration of its critical roles in pathophysiological processes has elevated CaMKII to a key target in the management of numerous diseases. The molecule KN-93 is the most widely used inhibitor for studying the cellular and in vivo functions of CaMKII. It is widely believed that KN-93 binds directly to CaMKII, thus preventing kinase activation by competing with Ca2+/CaM. Herein, we employed surface plasmon resonance, NMR, and isothermal titration calorimetry to characterize this presumed interaction. Our results revealed that KN-93 binds directly to Ca2+/CaM and not to CaMKII. This binding would disrupt the ability of Ca2+/CaM to interact with CaMKII, effectively inhibiting CaMKII activation. Our findings also indicated that KN-93 can specifically compete with a CaMKIIδ-derived peptide for binding to Ca2+/CaM. As indicated by the surface plasmon resonance and isothermal titration calorimetry data, apparently at least two KN-93 molecules can bind to Ca2+/CaM. Our findings provide new insight into how in vitro and in vivo data obtained with KN-93 should be interpreted. They further suggest that other Ca2+/CaM-dependent, non-CaMKII activities should be considered in KN-93-based mechanism-of-action studies and drug discovery efforts.
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7
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Xu M, Liu L, Yan Q. Allosterically Activated Protein Self-Assembly for the Construction of Helical Microfilaments with Tunable Helicity. Angew Chem Int Ed Engl 2018; 57:5029-5032. [DOI: 10.1002/anie.201801081] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Indexed: 12/27/2022]
Affiliation(s)
- Miaomiao Xu
- State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Engineering; Fudan University; Shanghai 200433 China
| | - Lianxiao Liu
- State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Engineering; Fudan University; Shanghai 200433 China
| | - Qiang Yan
- State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Engineering; Fudan University; Shanghai 200433 China
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8
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Xu M, Liu L, Yan Q. Allosterically Activated Protein Self-Assembly for the Construction of Helical Microfilaments with Tunable Helicity. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201801081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Miaomiao Xu
- State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Engineering; Fudan University; Shanghai 200433 China
| | - Lianxiao Liu
- State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Engineering; Fudan University; Shanghai 200433 China
| | - Qiang Yan
- State Key Laboratory of Molecular Engineering of Polymers; Department of Macromolecular Engineering; Fudan University; Shanghai 200433 China
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9
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Abstract
Calmodulin (CaM) regulation of voltage-gated calcium (CaV) channels is a powerful Ca2+ feedback mechanism that adjusts Ca2+ influx, affording rich mechanistic insights into Ca2+ decoding. CaM possesses a dual-lobed architecture, a salient feature of the myriad Ca2+-sensing proteins, where two homologous lobes that recognize similar targets hint at redundant signaling mechanisms. Here, by tethering CaM lobes, we demonstrate that bilobal architecture is obligatory for signaling to CaV channels. With one lobe bound, CaV carboxy tail rearranges itself, resulting in a preinhibited configuration precluded from Ca2+ feedback. Reconstitution of two lobes, even as separate molecules, relieves preinhibition and restores Ca2+ feedback. CaV channels thus detect the coincident binding of two Ca2+-free lobes to promote channel opening, a molecular implementation of a logical NOR operation that processes spatiotemporal Ca2+ signals bifurcated by CaM lobes. Overall, a unified scheme of CaV channel regulation by CaM now emerges, and our findings highlight the versatility of CaM to perform exquisite Ca2+ computations.
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10
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Owens DC. Meet the relatives: a reintroduction to the clinical pharmacology of ‘typical’ antipsychotics (Part 1). ACTA ACUST UNITED AC 2018. [DOI: 10.1192/apt.bp.109.006908] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SummaryA number of pragmatic trials have cast doubt on the concept of ‘atypicality’ in relation to antipsychotic drugs, and some commentators have argued that the dichotomy between ‘typical’ (‘first-generation’) and ‘atypical’ ('second-generation’) compounds is artificial and should be abandoned, leaving the entire class of antipsychotics available for consideration in more individualised treatment planning. However, younger psychiatrists now gain little or no experience in the use of older antipsychotics. This is the first of two articles addressing practical issues for consideration in prescribing the older antipsychotics available in the UK. It covers background, including the fundamental clinical action of antipsychotics, the nature of drug licensing and identification of pharmacological parameters that may be of value in prescribing decisions, and discusses the phenothiazines: chlorpromazine, promazine, levomepromazine, pericyazine, perphenazine, trifluoperazine and prochlorperazine.
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11
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Aprahamian ML, Tikunova SB, Price MV, Cuesta AF, Davis JP, Lindert S. Successful Identification of Cardiac Troponin Calcium Sensitizers Using a Combination of Virtual Screening and ROC Analysis of Known Troponin C Binders. J Chem Inf Model 2017; 57:3056-3069. [PMID: 29144742 DOI: 10.1021/acs.jcim.7b00536] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium-dependent cardiac muscle contraction is regulated by the protein complex troponin. Calcium binds to the N-terminal domain of troponin C (cNTnC) which initiates the process of contraction. Heart failure is a consequence of a disruption of this process. With the prevalence of this condition, a strong need exists to find novel compounds to increase the calcium sensitivity of cNTnC. Desirable are small chemical molecules that bind to the interface between cTnC and the cTnI switch peptide and exhibit calcium sensitizing properties by possibly stabilizing cTnC in an open conformation. To identify novel drug candidates, we employed a structure-based drug discovery protocol that incorporated the use of a relaxed complex scheme (RCS). In preparation for the virtual screening, cNTnC conformations were identified based on their ability to correctly predict known cNTnC binders using a receiver operating characteristics analysis. Following a virtual screen of the National Cancer Institute's Developmental Therapeutic Program database, a small number of molecules were experimentally tested using stopped-flow kinetics and steady-state fluorescence titrations. We identified two novel compounds, 3-(4-methoxyphenyl)-6,7-chromanediol (NSC600285) and 3-(4-methylphenyl)-7,8-chromanediol (NSC611817), that show increased calcium sensitivity of cTnC in the presence of the regulatory domain of cTnI. The effects of NSC600285 and NSC611817 on the calcium dissociation rate was stronger than that of the known calcium sensitizer bepridil. Thus, we identified a 3-phenylchromane group as a possible key pharmacophore in the sensitization of cardiac muscle contraction. Building on this finding is of interest to researchers working on development of drugs for calcium sensitization.
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Affiliation(s)
- Melanie L Aprahamian
- Department of Chemistry and Biochemistry, Ohio State University , Columbus, Ohio 43210, United States
| | - Svetlana B Tikunova
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Morgan V Price
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Andres F Cuesta
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Jonathan P Davis
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University , Columbus, Ohio 43210, United States
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12
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Wang L, Nick P. Cold sensing in grapevine-Which signals are upstream of the microtubular "thermometer". PLANT, CELL & ENVIRONMENT 2017; 40:2844-2857. [PMID: 28898434 DOI: 10.1111/pce.13066] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 08/23/2017] [Accepted: 08/28/2017] [Indexed: 05/09/2023]
Abstract
Plants can acquire freezing tolerance in response to cold but non-freezing temperatures. To efficiently activate this cold acclimation, low temperature has to be sensed and processed swiftly, a process that is linked with a transient elimination of microtubules. Here, we address cold-induced microtubules elimination in a grapevine cell line stably expressing a green fluorescent protein fusion of Arabidopsis TuB6, which allows to follow their response in vivo and to quantify this response by quantitative image analysis. We use time-course studies with several specific pharmacological inhibitors and activators to dissect the signalling events acting upstream of microtubules elimination. We find that microtubules disappear within 30 min after the onset of cold stress. We provide evidence for roles of calcium influx, membrane rigidification, and activation of NAD(P)H oxidase as factors in signal susception and amplification. We further conclude that a G-protein in concert with a phospholipase D convey the signal towards microtubules, whereas calmodulin seems to be not involved. Moreover, activation of jasmonate pathway in response to cold is required for an efficient microtubule response. We summarize our findings in a working model on a complex signalling hub at the membrane-cytoskeleton interphase that assembles the susception, perception and early transduction of cold signals.
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Affiliation(s)
- Lixin Wang
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, 76131, Karlsruhe, Germany
| | - Peter Nick
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, 76131, Karlsruhe, Germany
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13
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Waudby CA, Ramos A, Cabrita LD, Christodoulou J. Two-Dimensional NMR Lineshape Analysis. Sci Rep 2016; 6:24826. [PMID: 27109776 PMCID: PMC4843008 DOI: 10.1038/srep24826] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 03/31/2016] [Indexed: 12/18/2022] Open
Abstract
NMR titration experiments are a rich source of structural, mechanistic, thermodynamic and kinetic information on biomolecular interactions, which can be extracted through the quantitative analysis of resonance lineshapes. However, applications of such analyses are frequently limited by peak overlap inherent to complex biomolecular systems. Moreover, systematic errors may arise due to the analysis of two-dimensional data using theoretical frameworks developed for one-dimensional experiments. Here we introduce a more accurate and convenient method for the analysis of such data, based on the direct quantum mechanical simulation and fitting of entire two-dimensional experiments, which we implement in a new software tool, TITAN (TITration ANalysis). We expect the approach, which we demonstrate for a variety of protein-protein and protein-ligand interactions, to be particularly useful in providing information on multi-step or multi-component interactions.
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Affiliation(s)
- Christopher A Waudby
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 6BT, UK
| | - Andres Ramos
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 6BT, UK
| | - Lisa D Cabrita
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 6BT, UK
| | - John Christodoulou
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 6BT, UK
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14
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Feldkamp MD, Gakhar L, Pandey N, Shea MA. Opposing orientations of the anti-psychotic drug trifluoperazine selected by alternate conformations of M144 in calmodulin. Proteins 2015; 83:989-96. [PMID: 25694384 DOI: 10.1002/prot.24781] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/28/2015] [Accepted: 01/31/2015] [Indexed: 11/07/2022]
Abstract
The anti-psychotic drug trifluoperazine (TFP) is an antagonist observed to bind to calcium-saturated calmodulin ((Ca(2+) )4 -CaM) at ratios of 1:1 (1CTR), 2:1 (1A29), and 4:1 (1LIN). Each structure contains one TFP bound in the hydrophobic cleft of the C-domain of CaM. However, the orientation of the trifluoromethyl (CF3 ) moiety differs among them: it is buried in the C-domain cleft of 1A29 and 1LIN, but protrudes from 1CTR. We report a 2.0 Å resolution crystallographic structure (4RJD) of TFP bound to the (Ca(2+) )-saturated C-domain of CaM (CaMC ). The asymmetric unit contains two molecules of (Ca(2+) )2 -CaMC . Chain backbones were nearly identical, but the orientation of TFP in the cleft of Chain A matched 1A29/1LIN, while TFP bound to Chain B matched 1CTR. This was accommodated by a flip of the M144 sidechain and small changes in sidechains of M109 and M145. Docking simulations suggested that the rotamer conformation of M144 determined the orientation of TFP within the cleft of (Ca(2+) )2 -CaMC . Chains A and B show that the open cleft of (Ca(2+) )2 -CaMC is promiscuous in accepting TFP in reversed directions under the same crystallization conditions. Observing multiple orientations of an antagonist bound to a single protein highlights the challenge of designing highly specific pharmaceuticals, and may have importance for QSAR of other CF3 -containing drugs such as fluoxetine (anti-depressant) or efavirenz (reverse transcriptase inhibitor). This study emphasizes that a single structure of a complex represents an energetically accessible state, but does not necessarily show the full range of energetically equivalent states.
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Affiliation(s)
- Michael D Feldkamp
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242-1109
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15
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Vocke K, Dauner K, Hahn A, Ulbrich A, Broecker J, Keller S, Frings S, Möhrlen F. Calmodulin-dependent activation and inactivation of anoctamin calcium-gated chloride channels. ACTA ACUST UNITED AC 2014; 142:381-404. [PMID: 24081981 PMCID: PMC3787769 DOI: 10.1085/jgp.201311015] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium-dependent chloride channels serve critical functions in diverse biological systems. Driven by cellular calcium signals, the channels codetermine excitatory processes and promote solute transport. The anoctamin (ANO) family of membrane proteins encodes three calcium-activated chloride channels, named ANO 1 (also TMEM16A), ANO 2 (also TMEM16B), and ANO 6 (also TMEM16F). Here we examined how ANO 1 and ANO 2 interact with Ca2+/calmodulin using nonstationary current analysis during channel activation. We identified a putative calmodulin-binding domain in the N-terminal region of the channel proteins that is involved in channel activation. Binding studies with peptides indicated that this domain, a regulatory calmodulin-binding motif (RCBM), provides two distinct modes of interaction with Ca2+/calmodulin, one at submicromolar Ca2+ concentrations and one in the micromolar Ca2+ range. Functional, structural, and pharmacological data support the concept that calmodulin serves as a calcium sensor that is stably associated with the RCBM domain and regulates the activation of ANO 1 and ANO 2 channels. Moreover, the predominant splice variant of ANO 2 in the brain exhibits Ca2+/calmodulin-dependent inactivation, a loss of channel activity within 30 s. This property may curtail ANO 2 activity during persistent Ca2+ signals in neurons. Mutagenesis data indicated that the RCBM domain is also involved in ANO 2 inactivation, and that inactivation is suppressed in the retinal ANO 2 splice variant. These results advance the understanding of Ca2+ regulation in anoctamin Cl− channels and its significance for the physiological function that anoctamin channels subserve in neurons and other cell types.
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Affiliation(s)
- Kerstin Vocke
- Department of Molecular Physiology, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
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Fernandez TF, Samal AB, Bedwell GJ, Chen Y, Saad JS. Structural and biophysical characterization of the interactions between the death domain of Fas receptor and calmodulin. J Biol Chem 2013; 288:21898-908. [PMID: 23760276 DOI: 10.1074/jbc.m113.471821] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The extrinsic apoptotic pathway is initiated by cell surface death receptors such as Fas. Engagement of Fas by Fas ligand triggers a conformational change that allows Fas to interact with adaptor protein Fas-associated death domain (FADD) via the death domain, which recruits downstream signaling proteins to form the death-inducing signaling complex (DISC). Previous studies have shown that calmodulin (CaM) is recruited into the DISC in cholangiocarcinoma cells, suggesting a novel role of CaM in Fas-mediated signaling. CaM antagonists induce apoptosis through a Fas-related mechanism in cholangiocarcinoma and other cancer cell lines possibly by inhibiting Fas-CaM interactions. The structural determinants of Fas-CaM interaction and the underlying molecular mechanisms of inhibition, however, are unknown. Here we employed NMR and biophysical techniques to elucidate these mechanisms. Our data show that CaM binds to the death domain of Fas (FasDD) with an apparent dissociation constant (Kd) of ~2 μM and 2:1 CaM:FasDD stoichiometry. The interactions between FasDD and CaM are endothermic and entropically driven, suggesting that hydrophobic contacts are critical for binding. We also show that both the N- and C-terminal lobes of CaM are important for binding. NMR and surface plasmon resonance data show that three CaM antagonists (N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide, tamoxifen, and trifluoperazine) greatly inhibit Fas-CaM interactions by blocking the Fas-binding site on CaM. Our findings provide the first structural evidence for Fas-CaM interactions and mechanism of inhibition and provide new insight into the molecular basis for a novel role of CaM in regulating Fas-mediated apoptosis.
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Affiliation(s)
- Timothy F Fernandez
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Abstract
Although effective in treating an array of neurological disorders, antipsychotics are associated with deleterious metabolic side effects. Through high-throughput screening, we previously identified phenothiazine antipsychotics as modulators of the human insulin promoter. Here, we extended our initial finding to structurally diverse typical and atypical antipsychotics. We then identified the transforming growth factor beta (TGFβ) pathway as being involved in the effect of antipsychotics on the insulin promoter, finding that antipsychotics activated SMAD3, a downstream effector of the TGFβ pathway, through a receptor distinct from the TGFβ receptor family and known neurotransmitter receptor targets of antipsychotics. Of note, antipsychotics that do not cause metabolic side effects did not activate SMAD3. In vivo relevance was demonstrated by reanalysis of gene expression data from human brains treated with antipsychotics, which showed altered expression of SMAD3 responsive genes. This work raises the possibility that antipsychotics could be designed that retain beneficial CNS activity while lacking deleterious metabolic side effects.
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Affiliation(s)
- T. Cohen
- Sanford Children’s Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla, CA,Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA
| | | | - F. Levine
- Sanford Children’s Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla, CA,Address correspondence to: Dr. Fred Levine, Sanford Children’s Health Research Center, Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
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Affiliation(s)
| | | | - John E. Linz
- Department of Food Science and Human Nutrition,
- Department of Microbiology and Molecular Genetics,
- National Food Safety and Toxicology Center,
- Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824;
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Ochoa-Campuzano C, Sánchez J, García-Robles I, Real MD, Rausell C, Sánchez J. Identification of a calmodulin-binding site within the domain I of Bacillus thuringiensis Cry3Aa toxin. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2012; 81:53-62. [PMID: 22836907 DOI: 10.1002/arch.21044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Bacillus thuringiensis Cry3Aa toxin is a coleopteran specific toxin highly active against Colorado Potato Beetle (CPB).We have recently shown that Cry3Aa toxin is proteolytically cleaved by CPB midgut membrane associated metalloproteases and that this cleavage is inhibited by ADAM metalloprotease inhibitors. In the present study, we investigated whether the Cry3Aa toxin is a calmodulin (CaM) binding protein, as it is the case of several different ADAM shedding substrates. In pull-down assays using agarose beads conjugated with CaM, we demonstrated that Cry3Aa toxin specifically binds to CaM in a calcium-independent manner. Furthermore, we used gel shift assays and (1)H NMR spectra to demonstrate that CaM binds to a 16-amino acid synthetic peptide corresponding to residues N256-V271 within the domain I of Cry3Aa toxin. Finally, to investigate whether CaM has any effect on Cry3Aa toxin CPB midgut membrane associated proteolysis, cleavage assays were performed in the presence of the CaM-specific inhibitor trifluoperazine. We showed that trifluoperazine significantly increased Cry3Aa toxin proteolysis and also decreased Cry3Aa larval toxicity.
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Affiliation(s)
- Camila Ochoa-Campuzano
- Departamento de Genética, Facultad de Ciencias Biológicas, Universidad de Valencia, Valencia, Spain
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Johnstone AL, Reierson GW, Smith RP, Goldberg JL, Lemmon VP, Bixby JL. A chemical genetic approach identifies piperazine antipsychotics as promoters of CNS neurite growth on inhibitory substrates. Mol Cell Neurosci 2012; 50:125-35. [PMID: 22561309 DOI: 10.1016/j.mcn.2012.04.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 03/23/2012] [Accepted: 04/20/2012] [Indexed: 01/22/2023] Open
Abstract
Injury to the central nervous system (CNS) can result in lifelong loss of function due in part to the regenerative failure of CNS neurons. Inhibitory proteins derived from myelin and the astroglial scar are major barriers for the successful regeneration of injured CNS neurons. Previously, we described the identification of a novel compound, F05, which promotes neurite growth from neurons challenged with inhibitory substrates in vitro, and promotes axonal regeneration in vivo (Usher et al., 2010). To identify additional regeneration-promoting compounds, we used F05-induced gene expression profiles to query the Broad Institute Connectivity Map, a gene expression database of cells treated with >1300 compounds. Despite no shared chemical similarity, F05-induced changes in gene expression were remarkably similar to those seen with a group of piperazine phenothiazine antipsychotics (PhAPs). In contrast to antipsychotics of other structural classes, PhAPs promoted neurite growth of CNS neurons challenged with two different glial derived inhibitory substrates. Our pharmacological studies suggest a mechanism whereby PhAPs promote growth through antagonism of calmodulin signaling, independent of dopamine receptor antagonism. These findings shed light on mechanisms underlying neurite-inhibitory signaling, and suggest that clinically approved antipsychotic compounds may be repurposed for use in CNS injured patients.
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Affiliation(s)
- Andrea L Johnstone
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1400 NW 12th Ave, Miami, FL 33136, USA
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Dupuis L, Mousseau N. Understanding the EF-hand closing pathway using non-biased interatomic potentials. J Chem Phys 2012; 136:035101. [DOI: 10.1063/1.3671986] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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González-Andrade M, Rivera-Chávez J, Sosa-Peinado A, Figueroa M, Rodríguez-Sotres R, Mata R. Development of the Fluorescent Biosensor hCalmodulin (hCaM)L39C-monobromobimane(mBBr)/V91C-mBBr, a Novel Tool for Discovering New Calmodulin Inhibitors and Detecting Calcium. J Med Chem 2011; 54:3875-84. [DOI: 10.1021/jm200167g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - José Rivera-Chávez
- Facultad de Química, Universidad Nacional Autónoma de México, México DF 04510, México
| | | | - Mario Figueroa
- Facultad de Química, Universidad Nacional Autónoma de México, México DF 04510, México
| | | | - Rachel Mata
- Facultad de Química, Universidad Nacional Autónoma de México, México DF 04510, México
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