1
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Chung YK, Chan HY, Lee TY, Wong YH. Inhibition of adenylyl cyclase by GTPase-deficient Gα i is mechanistically different from that mediated by receptor-activated Gα i. Cell Commun Signal 2024; 22:218. [PMID: 38581012 PMCID: PMC10996109 DOI: 10.1186/s12964-024-01572-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Accepted: 03/16/2024] [Indexed: 04/07/2024] Open
Abstract
Signal transduction through G protein-coupled receptors (GPCRs) has been a major focus in cell biology for decades. Numerous disorders are associated with GPCRs that utilize Gi proteins to inhibit adenylyl cyclase (AC) as well as regulate other effectors. Several early studies have successfully defined the AC-interacting domains of several members of Gαi by measuring the loss of activity upon homologous replacements of putative regions of constitutive active Gαi mutants. However, whether such findings can indeed be translated into the context of a receptor-activated Gαi have not been rigorously verified. To address this issue, an array of known and new chimeric mutations was introduced into GTPase-deficient Q204L (QL) and R178C (RC) mutants of Gαi1, followed by examinations on their ability to inhibit AC. Surprisingly, most chimeras failed to abolish the constitutive activity brought on by the QL mutation, while some were able to eliminate the inhibitory activity of RC mutants. Receptor-mediated inhibition of AC was similarly observed in the same chimeric constructs harbouring the pertussis toxin (PTX)-resistant C351I mutation. Moreover, RC-bearing loss-of-function chimeras appeared to be hyper-deactivated by endogenous RGS protein. Molecular docking revealed a potential interaction between AC and the α3/β5 loop of Gαi1. Subsequent cAMP assays support a cooperative action of the α3/β5 loop, the α4 helix, and the α4/β6 loop in mediating AC inhibition by Gαi1-i3. Our results unveiled a notable functional divergence between constitutively active mutants and receptor-activated Gαi1 to inhibit AC, and identified a previously unknown AC-interacting domain of Gαi subunits. These results collectively provide valuable insights on the mechanism of AC inhibition in the cellular environment.
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Affiliation(s)
- Yin Kwan Chung
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, 04103, Leipzig, Germany
| | - Ho Yung Chan
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China
| | - Tung Yeung Lee
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China
| | - Yung Hou Wong
- Division of Life Science and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, China.
- State Key Laboratory of Molecular Neuroscience, and the Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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2
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Yang L, Finlay DB, Green HM, Zhu X, Glass M, Duffull S. A quantitative pharmacology model for cannabinoid CB 1 receptor mediated by Gi/Gs protein competition. Br J Pharmacol 2024; 181:1324-1340. [PMID: 38072805 DOI: 10.1111/bph.16293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 10/29/2023] [Accepted: 11/20/2023] [Indexed: 01/14/2024] Open
Abstract
BACKGROUND AND PURPOSE Orthosteric agonism of the CB1 receptor normally associates with Gi signalling resulting in a net inhibition of cAMP production. Empirical evidence shows CB1 causes a net cAMP stimulation through Gs coupling under two conditions: co-stimulation with the D2 receptor and high-level CB1 expression. Two hypotheses have been proposed to account for these paradoxical effects, (1) Gi is consumed by coupling to D2 or extra CB1 and excess CB1 binds to Gs and (2), the formation of dimers CB1 -CB1 or CB1 -D2 switches Gi/Gs preference. This study explored the mechanisms of Gi/Gs preference based on a mathematical model of the CB1 receptor. EXPERIMENTAL APPROACH The model was based on Hypothesis 1 and known mechanisms. The model was calibrated to align with multiple types of data (cAMP, Gi dissociation and internalisation). The key step of Hypothesis 1 was examined by simulation from the model. An experiment was proposed to distinguish Hypothesis 1 and 2. KEY RESULTS The model successfully descripted multiple types of data under Hypothesis 1. Simulations from the model indicated that precoupling of G protein with receptors is necessary for this hypothesis. The model designed experiments to distinguish Hypothesis 1 and 2 by increasing Gi & Gs in parallel with CB1 overexpression. The two hypotheses result in distinct cAMP responses. CONCLUSION AND IMPLICATIONS A mathematical model of CB1 -regulated Gi/Gs pathways was developed. It indicated Hypothesis 1 is feasible and G protein precoupling is a key step causing cAMP signalling switch. The model-designed experiments provided guides for future experimentation.
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Affiliation(s)
- Liang Yang
- Otago Pharmacometrics Group, School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - David B Finlay
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand
| | - Hayley M Green
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand
| | - Xiao Zhu
- Department of Clinical Pharmacy and Pharmacy Administration, School of Pharmacy, Fudan University, Shanghai, China
| | - Michelle Glass
- Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand
| | - Stephen Duffull
- Otago Pharmacometrics Group, School of Pharmacy, University of Otago, Dunedin, New Zealand
- Certara, Princeton, New Jersey, USA
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3
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Luebbers A, Gonzalez-Hernandez AJ, Zhou M, Eyles SJ, Levitz J, Garcia-Marcos M. Dissecting the molecular basis for the modulation of neurotransmitter GPCR signaling by GINIP. Structure 2024; 32:47-59.e7. [PMID: 37989308 PMCID: PMC10872408 DOI: 10.1016/j.str.2023.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/23/2023] [Accepted: 10/25/2023] [Indexed: 11/23/2023]
Abstract
It is well established that G-protein-coupled receptors (GPCRs) stimulated by neurotransmitters are critical for neuromodulation. Much less is known about how heterotrimeric G-protein (Gαβγ) regulation after receptor-mediated activation contributes to neuromodulation. Recent evidence indicates that the neuronal protein GINIP shapes GPCR inhibitory neuromodulation via a unique mechanism of G-protein regulation that controls pain and seizure susceptibility. However, the molecular basis of this mechanism remains ill-defined because the structural determinants of GINIP responsible for binding and regulating G proteins are not known. Here, we combined hydrogen-deuterium exchange mass spectrometry, computational structure predictions, biochemistry, and cell-based biophysical assays to demonstrate an effector-like binding mode of GINIP to Gαi. Specific amino acids of GINIP's PHD domain first loop are essential for G-protein binding and subsequent regulation of Gαi-GTP and Gβγ signaling upon neurotransmitter GPCR stimulation. In summary, these findings shed light onto the molecular basis for a post-receptor mechanism of G-protein regulation that fine-tunes inhibitory neuromodulation.
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Affiliation(s)
- Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | | | - Myles Zhou
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Stephen J Eyles
- Mass Spectrometry Core Facility, Institute for Applied Life Sciences (IALS), University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10064, USA; Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA.
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4
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Hiramatsu Y, Nishida T, Ota N, Tamaki Y, Nugraha DK, Horiguchi Y. DAT, deacylating autotransporter toxin, from Bordetella parapertussis demyristoylates Gα i GTPases and contributes to cough. Proc Natl Acad Sci U S A 2023; 120:e2308260120. [PMID: 37748060 PMCID: PMC10556565 DOI: 10.1073/pnas.2308260120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/28/2023] [Indexed: 09/27/2023] Open
Abstract
The pathogenic bacteria Bordetella pertussis and Bordetella parapertussis cause pertussis (whooping cough) and pertussis-like disease, respectively, both of which are characterized by paroxysmal coughing. We previously reported that pertussis toxin (PTx), which inactivates heterotrimeric GTPases of the Gi family through ADP-ribosylation of their α subunits, causes coughing in combination with Vag8 and lipid A in B. pertussis infection. In contrast, the mechanism of cough induced by B. parapertussis, which produces Vag8 and lipopolysaccharide (LPS) containing lipid A, but not PTx, remained to be elucidated. Here, we show that a toxin we named deacylating autotransporter toxin (DAT) of B. parapertussis inactivates heterotrimeric Gi GTPases through demyristoylation of their α subunits and contributes to cough production along with Vag8 and LPS. These results indicate that DAT plays a role in B. parapertussis infection in place of PTx.
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Affiliation(s)
- Yukihiro Hiramatsu
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Takashi Nishida
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Natsuko Ota
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Yuki Tamaki
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Dendi K. Nugraha
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Yasuhiko Horiguchi
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
- Center for Infectious Disease Education and Research, Osaka University, Suita, Osaka565-0871, Japan
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5
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Park JC, Luebbers A, Dao M, Semeano A, Nguyen AM, Papakonstantinou MP, Broselid S, Yano H, Martemyanov KA, Garcia-Marcos M. Fine-tuning GPCR-mediated neuromodulation by biasing signaling through different G protein subunits. Mol Cell 2023; 83:2540-2558.e12. [PMID: 37390816 PMCID: PMC10527995 DOI: 10.1016/j.molcel.2023.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/28/2023] [Accepted: 06/02/2023] [Indexed: 07/02/2023]
Abstract
G-protein-coupled receptors (GPCRs) mediate neuromodulation through the activation of heterotrimeric G proteins (Gαβγ). Classical models depict that G protein activation leads to a one-to-one formation of Gα-GTP and Gβγ species. Each of these species propagates signaling by independently acting on effectors, but the mechanisms by which response fidelity is ensured by coordinating Gα and Gβγ responses remain unknown. Here, we reveal a paradigm of G protein regulation whereby the neuronal protein GINIP (Gα inhibitory interacting protein) biases inhibitory GPCR responses to favor Gβγ over Gα signaling. Tight binding of GINIP to Gαi-GTP precludes its association with effectors (adenylyl cyclase) and, simultaneously, with regulator-of-G-protein-signaling (RGS) proteins that accelerate deactivation. As a consequence, Gαi-GTP signaling is dampened, whereas Gβγ signaling is enhanced. We show that this mechanism is essential to prevent the imbalances of neurotransmission that underlie increased seizure susceptibility in mice. Our findings reveal an additional layer of regulation within a quintessential mechanism of signal transduction that sets the tone of neurotransmission.
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Affiliation(s)
- Jong-Chan Park
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Alex Luebbers
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Maria Dao
- U.F. Scripps Biomedical Research, University of Florida, Jupiter, FL 33458, USA
| | - Ana Semeano
- Department of Pharmaceutical Sciences, Center for Drug Discovery, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | - Anh Minh Nguyen
- Department of Pharmaceutical Sciences, Center for Drug Discovery, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | - Maria P Papakonstantinou
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Stefan Broselid
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA
| | - Hideaki Yano
- Department of Pharmaceutical Sciences, Center for Drug Discovery, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA
| | | | - Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA 02118, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, MA 02115, USA.
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6
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Schultz JE. The evolutionary conservation of eukaryotic membrane-bound adenylyl cyclase isoforms. Front Pharmacol 2022; 13:1009797. [PMID: 36238545 PMCID: PMC9552081 DOI: 10.3389/fphar.2022.1009797] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/06/2022] [Indexed: 11/18/2022] Open
Abstract
The nine membrane-delimited eukaryotic adenylyl cyclases are pseudoheterodimers with an identical domain order of seven (nine) distinct subdomains. Bioinformatics show that the protein evolved from a monomeric bacterial progenitor by gene duplication and fusion probably in a primordial eukaryotic cell around 1.5 billion years ago. Over a timespan of about 1 billion years, the first fusion product diverged into nine highly distinct pseudoheterodimeric isoforms. The evolutionary diversification ended approximately 0.5 billion years ago because the present isoforms are found in the living fossil coelacanth, a fish. Except for the two catalytic domains, C1 and C2, the mAC isoforms are fully diverged. Yet, within each isoform a high extent of conservation of respective subdomains is found. This applies to the C- and N-termini, a long linker region between the protein halves (C1b), two short cyclase-transducing-elements (CTE) and notably to the two hexahelical membrane domains TM1 and TM2. Except for the membrane anchor all subdomains were previously implicated in regulatory modalities. The bioinformatic results unequivocally indicate that the membrane anchors must possess an important regulatory function specifically tailored for each mAC isoform.
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7
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van Keulen SC, Martin J, Colizzi F, Frezza E, Trpevski D, Diaz NC, Vidossich P, Rothlisberger U, Hellgren Kotaleski J, Wade RC, Carloni P. Multiscale molecular simulations to investigate adenylyl cyclase‐based signaling in the brain. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Siri C. van Keulen
- Computational Structural Biology Group, Bijvoet Center for Biomolecular Research, Science for Life, Faculty of Science – Chemistry Utrecht University Utrecht The Netherlands
| | - Juliette Martin
- CNRS, UMR 5086 Molecular Microbiology and Structural Biochemistry University of Lyon Lyon France
| | - Francesco Colizzi
- Molecular Ocean Laboratory, Department of Marine Biology and Oceanography Institute of Marine Sciences, ICM‐CSIC Barcelona Spain
| | - Elisa Frezza
- Université Paris Cité, CiTCoM, CNRS Paris France
| | - Daniel Trpevski
- Science for Life Laboratory, School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm
| | - Nuria Cirauqui Diaz
- CNRS, UMR 5086 Molecular Microbiology and Structural Biochemistry University of Lyon Lyon France
| | - Pietro Vidossich
- Molecular Modeling and Drug Discovery Lab Istituto Italiano di Tecnologia Genoa Italy
| | - Ursula Rothlisberger
- Laboratory of Computational Chemistry and Biochemistry Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne
| | - Jeanette Hellgren Kotaleski
- Science for Life Laboratory, School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm
- Department of Neuroscience Karolinska Institute Stockholm
| | - Rebecca C. Wade
- Molecular and Cellular Modeling Group Heidelberg Institute for Theoretical Studies (HITS) Heidelberg Germany
- Center for Molecular Biology (ZMBH), DKFZ‐ZMBH Alliance, and Interdisciplinary Center for Scientific Computing (IWR) Heidelberg University Heidelberg Germany
| | - Paolo Carloni
- Institute for Neuroscience and Medicine (INM‐9) and Institute for Advanced Simulations (IAS‐5) “Computational biomedicine” Forschungszentrum Jülich Jülich Germany
- INM‐11 JARA‐Institute: Molecular Neuroscience and Neuroimaging Forschungszentrum Jülich Jülich Germany
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8
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Ferré S, Ciruela F, Dessauer CW, González-Maeso J, Hébert TE, Jockers R, Logothetis DE, Pardo L. G protein-coupled receptor-effector macromolecular membrane assemblies (GEMMAs). Pharmacol Ther 2022; 231:107977. [PMID: 34480967 PMCID: PMC9375844 DOI: 10.1016/j.pharmthera.2021.107977] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/11/2021] [Accepted: 08/17/2021] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest group of receptors involved in cellular signaling across the plasma membrane and a major class of drug targets. The canonical model for GPCR signaling involves three components - the GPCR, a heterotrimeric G protein and a proximal plasma membrane effector - that have been generally thought to be freely mobile molecules able to interact by 'collision coupling'. Here, we synthesize evidence that supports the existence of GPCR-effector macromolecular membrane assemblies (GEMMAs) comprised of specific GPCRs, G proteins, plasma membrane effector molecules and other associated transmembrane proteins that are pre-assembled prior to receptor activation by agonists, which then leads to subsequent rearrangement of the GEMMA components. The GEMMA concept offers an alternative and complementary model to the canonical collision-coupling model, allowing more efficient interactions between specific signaling components, as well as the integration of the concept of GPCR oligomerization as well as GPCR interactions with orphan receptors, truncated GPCRs and other membrane-localized GPCR-associated proteins. Collision-coupling and pre-assembled mechanisms are not exclusive and likely both operate in the cell, providing a spectrum of signaling modalities which explains the differential properties of a multitude of GPCRs in their different cellular environments. Here, we explore the unique pharmacological characteristics of individual GEMMAs, which could provide new opportunities to therapeutically modulate GPCR signaling.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Addiction, Intramural Research Program, NIH, DHHS, Baltimore, MD, USA.
| | - Francisco Ciruela
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Institute of Neurosciences, IDIBELL, University of Barcelona, L’Hospitalet de Llobregat, Spain
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Javier González-Maeso
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Terence E. Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec
| | - Ralf Jockers
- University of Paris, Institute Cochin, INSERM, CNRS, Paris, France
| | - Diomedes E. Logothetis
- Laboratory of Electrophysiology, Departments of Pharmaceutical Sciences, Chemistry and Chemical Biology and Center for Drug Discovery, School of Pharmacy at the Bouvé College of Health Sciences and College of Science, Northeastern University, Boston, Massachusetts, USA
| | - Leonardo Pardo
- Laboratory of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Autonomous University of Barcelona, Bellaterra, Spain
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9
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Anandakrishnan R, Tobey H, Nguyen S, Sandoval O, Klein BG, Costa BM. Cranial manipulation affects cholinergic pathway gene expression in aged rats. J Osteopath Med 2022; 122:95-103. [PMID: 34995434 DOI: 10.1515/jom-2021-0183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 09/01/2021] [Indexed: 11/15/2022]
Abstract
CONTEXT Age-dependent dementia is a devastating disorder afflicting a growing older population. Although pharmacological agents improve symptoms of dementia, age-related comorbidities combined with adverse effects often outweigh their clinical benefits. Therefore, nonpharmacological therapies are being investigated as an alternative. In a previous pilot study, aged rats demonstrated improved spatial memory after osteopathic cranial manipulative medicine (OCMM) treatment. OBJECTIVES In this continuation of the pilot study, we examine the effect of OCMM on gene expression to elicit possible explanations for the improvement in spatial memory. METHODS OCMM was performed on six of 12 elderly rats every day for 7 days. Rats were then euthanized to obtain the brain tissue, from which RNA samples were extracted. RNA from three treated and three controls were of sufficient quality for sequencing. These samples were sequenced utilizing next-generation sequencing from Illumina NextSeq. The Cufflinks software suite was utilized to assemble transcriptomes and quantify the RNA expression level for each sample. RESULTS Transcriptome analysis revealed that OCMM significantly affected the expression of 36 genes in the neuronal pathway (false discovery rate [FDR] <0.004). The top five neuronal genes with the largest-fold change were part of the cholinergic neurotransmission mechanism, which is known to affect cognitive function. In addition, 39.9% of 426 significant differentially expressed (SDE) genes (FDR<0.004) have been previously implicated in neurological disorders. Overall, changes in SDE genes combined with their role in central nervous system signaling pathways suggest a connection to previously reported OCMM-induced behavioral and biochemical changes in aged rats. CONCLUSIONS Results from this pilot study provide sufficient evidence to support a more extensive study with a larger sample size. Further investigation in this direction will provide a better understanding of the molecular mechanisms of OCMM and its potential in clinical applications. With clinical validation, OCMM could represent a much-needed low-risk adjunct treatment for age-related dementia including Alzheimer's disease.
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Affiliation(s)
- Ramu Anandakrishnan
- Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, VA, USA.,Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.,Gibbs Cancer Center and Research Institute, Spartanburg, SC, USA
| | - Hope Tobey
- Sports and Osteopathic Medicine, Edward Via College of Osteopathic Medicine, Blacksburg, VA, USA
| | - Steven Nguyen
- Edward Via College of Osteopathic Medicine, Blacksburg, VA, USA
| | - Osscar Sandoval
- Edward Via College of Osteopathic Medicine, Blacksburg, VA, USA
| | - Bradley G Klein
- Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.,School of Neuroscience, Virginia Tech, Blacksburg, VA, USA
| | - Blaise M Costa
- Biomedical Sciences, Edward Via College of Osteopathic Medicine, Blacksburg, VA, USA.,Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
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10
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Colizzi F, Orozco M. Probing allosteric regulations with coevolution-driven molecular simulations. SCIENCE ADVANCES 2021; 7:eabj0786. [PMID: 34516882 PMCID: PMC8442858 DOI: 10.1126/sciadv.abj0786] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Protein-mediated allosteric regulations are essential in biology, but their quantitative characterization continues to posit formidable challenges for both experiments and computations. Here, we combine coevolutionary information, multiscale molecular simulations, and free-energy methods to interrogate and quantify the allosteric regulation of functional changes in protein complexes. We apply this approach to investigate the regulation of adenylyl cyclase (AC) by stimulatory and inhibitory G proteins—a prototypical allosteric system that has long escaped from in-depth molecular characterization. We reveal a surprisingly simple ON/OFF regulation of AC functional dynamics through multiple pathways of information transfer. The binding of G proteins reshapes the free-energy landscape of AC following the classical population-shift paradigm. The model agrees with structural and biochemical data and reveals previously unknown experimentally consistent intermediates. Our approach showcases a general strategy to explore uncharted functional space in complex biomolecular regulations.
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Affiliation(s)
- Francesco Colizzi
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Carrer de Baldiri Reixac 10, Barcelona 08028, Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Carrer de Baldiri Reixac 10, Barcelona 08028, Spain
- Departament de Bioquímica i Biomedicina, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 647, Barcelona 08028, Spain
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11
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Urakubo H, Yagishita S, Kasai H, Kubota Y, Ishii S. The critical balance between dopamine D2 receptor and RGS for the sensitive detection of a transient decay in dopamine signal. PLoS Comput Biol 2021; 17:e1009364. [PMID: 34591840 PMCID: PMC8483376 DOI: 10.1371/journal.pcbi.1009364] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 08/18/2021] [Indexed: 12/19/2022] Open
Abstract
In behavioral learning, reward-related events are encoded into phasic dopamine (DA) signals in the brain. In particular, unexpected reward omission leads to a phasic decrease in DA (DA dip) in the striatum, which triggers long-term potentiation (LTP) in DA D2 receptor (D2R)-expressing spiny-projection neurons (D2 SPNs). While this LTP is required for reward discrimination, it is unclear how such a short DA-dip signal (0.5-2 s) is transferred through intracellular signaling to the coincidence detector, adenylate cyclase (AC). In the present study, we built a computational model of D2 signaling to determine conditions for the DA-dip detection. The DA dip can be detected only if the basal DA signal sufficiently inhibits AC, and the DA-dip signal sufficiently disinhibits AC. We found that those two requirements were simultaneously satisfied only if two key molecules, D2R and regulators of G protein signaling (RGS) were balanced within a certain range; this balance has indeed been observed in experimental studies. We also found that high level of RGS was required for the detection of a 0.5-s short DA dip, and the analytical solutions for these requirements confirmed their universality. The imbalance between D2R and RGS is associated with schizophrenia and DYT1 dystonia, both of which are accompanied by abnormal striatal LTP. Our simulations suggest that D2 SPNs in patients with schizophrenia and DYT1 dystonia cannot detect short DA dips. We finally discussed that such psychiatric and movement disorders can be understood in terms of the imbalance between D2R and RGS.
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Affiliation(s)
- Hidetoshi Urakubo
- Integrated Systems Biology Laboratory, Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan
- Section of Electron Microscopy, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Sho Yagishita
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan
| | - Haruo Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan
| | - Yoshiyuki Kubota
- Section of Electron Microscopy, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan
| | - Shin Ishii
- Integrated Systems Biology Laboratory, Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan
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12
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O'Brien JB, Roman DL. Novel treatments for chronic pain: moving beyond opioids. Transl Res 2021; 234:1-19. [PMID: 33727192 DOI: 10.1016/j.trsl.2021.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023]
Abstract
It is essential that safe and effective treatment options be available to patients suffering from chronic pain. The emergence of an opioid epidemic has shaped public opinions and created stigmas surrounding the use of opioids for the management of pain. This reality, coupled with high risk of adverse effects from chronic opioid use, has led chronic pain patients and their healthcare providers to utilize nonopioid treatment approaches. In this review, we will explore a number of cellular reorganizations that are associated with the development and progression of chronic pain. We will also discuss the safety and efficacy of opioid and nonopioid treatment options for chronic pain. Finally, we will review the evidence for adenylyl cyclase type 1 (AC1) as a novel target for the treatment of chronic pain.
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Affiliation(s)
- Joseph B O'Brien
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, Iowa
| | - David L Roman
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, Iowa; Iowa Neuroscience Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.
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13
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Zhang X, Pizzoni A, Hong K, Naim N, Qi C, Korkhov V, Altschuler DL. CAP1 binds and activates adenylyl cyclase in mammalian cells. Proc Natl Acad Sci U S A 2021; 118:e2024576118. [PMID: 34099549 PMCID: PMC8214675 DOI: 10.1073/pnas.2024576118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
CAP1 (Cyclase-Associated Protein 1) is highly conserved in evolution. Originally identified in yeast as a bifunctional protein involved in Ras-adenylyl cyclase and F-actin dynamics regulation, the adenylyl cyclase component seems to be lost in mammalian cells. Prompted by our recent identification of the Ras-like small GTPase Rap1 as a GTP-independent but geranylgeranyl-specific partner for CAP1, we hypothesized that CAP1-Rap1, similar to CAP-Ras-cyclase in yeast, might play a critical role in cAMP dynamics in mammalian cells. In this study, we report that CAP1 binds and activates mammalian adenylyl cyclase in vitro, modulates cAMP in live cells in a Rap1-dependent manner, and affects cAMP-dependent proliferation. Utilizing deletion and mutagenesis approaches, we mapped the interaction of CAP1-cyclase with CAP's N-terminal domain involving critical leucine residues in the conserved RLE motifs and adenylyl cyclase's conserved catalytic loops (e.g., C1a and/or C2a). When combined with a FRET-based cAMP sensor, CAP1 overexpression-knockdown strategies, and the use of constitutively active and negative regulators of Rap1, our studies highlight a critical role for CAP1-Rap1 in adenylyl cyclase regulation in live cells. Similarly, we show that CAP1 modulation significantly affected cAMP-mediated proliferation in an RLE motif-dependent manner. The combined study indicates that CAP1-cyclase-Rap1 represents a regulatory unit in cAMP dynamics and biology. Since Rap1 is an established downstream effector of cAMP, we advance the hypothesis that CAP1-cyclase-Rap1 represents a positive feedback loop that might be involved in cAMP microdomain establishment and localized signaling.
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Affiliation(s)
- Xuefeng Zhang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Alejandro Pizzoni
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Kyoungja Hong
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Nyla Naim
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Chao Qi
- Institute of Molecular Biology and Biophysics, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Volodymyr Korkhov
- Institute of Molecular Biology and Biophysics, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Daniel L Altschuler
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261;
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14
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Nubbemeyer B, Pepanian A, Paul George AA, Imhof D. Strategies towards Targeting Gαi/s Proteins: Scanning of Protein-Protein Interaction Sites To Overcome Inaccessibility. ChemMedChem 2021; 16:1696-1715. [PMID: 33615736 PMCID: PMC8252600 DOI: 10.1002/cmdc.202100039] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Indexed: 12/16/2022]
Abstract
Heterotrimeric G proteins are classified into four subfamilies and play a key role in signal transduction. They transmit extracellular signals to intracellular effectors subsequent to the activation of G protein-coupled receptors (GPCRs), which are targeted by over 30 % of FDA-approved drugs. However, addressing G proteins as drug targets represents a compelling alternative, for example, when G proteins act independently of the corresponding GPCRs, or in cases of complex multifunctional diseases, when a large number of different GPCRs are involved. In contrast to Gαq, efforts to target Gαi/s by suitable chemical compounds has not been successful so far. Here, a comprehensive analysis was conducted examining the most important interface regions of Gαi/s with its upstream and downstream interaction partners. By assigning the existing compounds and the performed approaches to the respective interfaces, the druggability of the individual interfaces was ranked to provide perspectives for selective targeting of Gαi/s in the future.
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Affiliation(s)
- Britta Nubbemeyer
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| | - Anna Pepanian
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
| | | | - Diana Imhof
- Pharmaceutical Biochemistry and BioanalyticsPharmaceutical InstituteUniversity of BonnAn der Immenburg 453121BonnGermany
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15
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Cross-Talk Between the Adenylyl Cyclase/cAMP Pathway and Ca 2+ Homeostasis. Rev Physiol Biochem Pharmacol 2021; 179:73-116. [PMID: 33398503 DOI: 10.1007/112_2020_55] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cyclic AMP and Ca2+ are the first second or intracellular messengers identified, unveiling the cellular mechanisms activated by a plethora of extracellular signals, including hormones. Cyclic AMP generation is catalyzed by adenylyl cyclases (ACs), which convert ATP into cAMP and pyrophosphate. By the way, Ca2+, as energy, can neither be created nor be destroyed; Ca2+ can only be transported, from one compartment to another, or chelated by a variety of Ca2+-binding molecules. The fine regulation of cytosolic concentrations of cAMP and free Ca2+ is crucial in cell function and there is an intimate cross-talk between both messengers to fine-tune the cellular responses. Cancer is a multifactorial disease resulting from a combination of genetic and environmental factors. Frequent cases of cAMP and/or Ca2+ homeostasis remodeling have been described in cancer cells. In those tumoral cells, cAMP and Ca2+ signaling plays a crucial role in the development of hallmarks of cancer, including enhanced proliferation and migration, invasion, apoptosis resistance, or angiogenesis. This review summarizes the cross-talk between the ACs/cAMP and Ca2+ intracellular pathways with special attention to the functional and reciprocal regulation between Orai1 and AC8 in normal and cancer cells.
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16
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Narzi D, van Keulen SC, Röthlisberger U. Gαi1 inhibition mechanism of ATP-bound adenylyl cyclase type 5. PLoS One 2021; 16:e0245197. [PMID: 33493164 PMCID: PMC7833170 DOI: 10.1371/journal.pone.0245197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 12/25/2020] [Indexed: 01/17/2023] Open
Abstract
Conversion of adenosine triphosphate (ATP) to the second messenger cyclic adenosine monophosphate (cAMP) is an essential reaction mechanism that takes place in eukaryotes, triggering a variety of signal transduction pathways. ATP conversion is catalyzed by the enzyme adenylyl cyclase (AC), which can be regulated by binding inhibitory, Gαi, and stimulatory, Gαs subunits. In the past twenty years, several crystal structures of AC in isolated form and complexed to Gαs subunits have been resolved. Nevertheless, the molecular basis of the inhibition mechanism of AC, induced by Gαi, is still far from being fully understood. Here, classical molecular dynamics simulations of the isolated holo AC protein type 5 and the holo binary complex AC5:Gαi have been analyzed to investigate the conformational impact of Gαi association on ATP-bound AC5. The results show that Gαi appears to inhibit the activity of AC5 by preventing the formation of a reactive ATP conformation.
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Affiliation(s)
- Daniele Narzi
- Institut des Sciences et Ingénierie Chimiques, École Polytechnicque Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Siri C. van Keulen
- Institut des Sciences et Ingénierie Chimiques, École Polytechnicque Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Ursula Röthlisberger
- Institut des Sciences et Ingénierie Chimiques, École Polytechnicque Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- * E-mail:
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17
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Frezza E, Amans TM, Martin J. Allosteric Inhibition of Adenylyl Cyclase Type 5 by G-Protein: A Molecular Dynamics Study. Biomolecules 2020; 10:E1330. [PMID: 32957635 PMCID: PMC7563791 DOI: 10.3390/biom10091330] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 11/17/2022] Open
Abstract
Adenylyl cyclases (ACs) have a crucial role in many signal transduction pathways, in particular in the intricate control of cyclic AMP (cAMP) generation from adenosine triphosphate (ATP). Using homology models developed from existing structural data and docking experiments, we have carried out all-atom, microsecond-scale molecular dynamics simulations on the AC5 isoform of adenylyl cyclase bound to the inhibitory G-protein subunit Gαi in the presence and in the absence of ATP. The results show that Gαi has significant effects on the structure and flexibility of adenylyl cyclase, as observed earlier for the binding of ATP and Gsα. New data on Gαi bound to the C1 domain of AC5 help explain how Gαi inhibits enzyme activity and obtain insight on its regulation. Simulations also suggest a crucial role of ATP in the regulation of the stimulation and inhibition of AC5.
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Affiliation(s)
- Elisa Frezza
- CiTCoM, CNRS, Université de Paris, F-75006 Paris, France
| | - Tina-Méryl Amans
- CNRS, UMR 5086 Molecular Microbiology and Structural Biochemistry, University of Lyon, F-69367 Lyon, France;
| | - Juliette Martin
- CNRS, UMR 5086 Molecular Microbiology and Structural Biochemistry, University of Lyon, F-69367 Lyon, France;
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18
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Garcia-Marcos M, Parag-Sharma K, Marivin A, Maziarz M, Luebbers A, Nguyen LT. Optogenetic activation of heterotrimeric G-proteins by LOV2GIVe, a rationally engineered modular protein. eLife 2020; 9:60155. [PMID: 32936073 PMCID: PMC7515630 DOI: 10.7554/elife.60155] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/15/2020] [Indexed: 12/24/2022] Open
Abstract
Heterotrimeric G-proteins are signal transducers involved in mediating the action of many natural extracellular stimuli and many therapeutic agents. Non-invasive approaches to manipulate the activity of G-proteins with high precision are crucial to understand their regulation in space and time. Here, we developed LOV2GIVe, an engineered modular protein that allows the activation of heterotrimeric G-proteins with blue light. This optogenetic construct relies on a versatile design that differs from tools previously developed for similar purposes, that is metazoan opsins, which are light-activated G-protein-coupled receptors (GPCRs). Instead, LOV2GIVe consists of the fusion of a G-protein activating peptide derived from a non-GPCR regulator of G-proteins to a small plant protein domain, such that light uncages the G-protein activating module. Targeting LOV2GIVe to cell membranes allowed for light-dependent activation of Gi proteins in different experimental systems. In summary, LOV2GIVe expands the armamentarium and versatility of tools available to manipulate heterotrimeric G-protein activity.
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Affiliation(s)
- Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Kshitij Parag-Sharma
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Arthur Marivin
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Marcin Maziarz
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Alex Luebbers
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
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19
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Nanometric targeting of type 9 adenylyl cyclase in heart. Biochem Soc Trans 2020; 47:1749-1756. [PMID: 31769471 DOI: 10.1042/bst20190227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022]
Abstract
Adenylyl cyclases (ACs) convert ATP into the classical second messenger cyclic adenosine monophosphate (cAMP). Cardiac ACs, specifically AC5, AC6, and AC9, regulate cAMP signaling controlling functional outcomes such as heart rate, contractility and relaxation, gene regulation, stress responses, and glucose and lipid metabolism. With so many distinct functional outcomes for a single second messenger, the cell creates local domains of cAMP signaling to correctly relay signals. Targeting of ACs to A-kinase anchoring proteins (AKAPs) not only localizes ACs, but also places them within signaling nanodomains, where cAMP levels and effects can be highly regulated. Here we will discuss the recent work on the structure, regulation and physiological functions of AC9 in the heart, where it accounts for <3% of total AC activity. Despite the small contribution of AC9 to total cardiac cAMP production, AC9 binds and regulates local PKA phosphorylation of Yotiao-IKs and Hsp20, demonstrating a role for nanometric targeting of AC9.
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20
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The chilling of adenylyl cyclase 9 and its translational potential. Cell Signal 2020; 70:109589. [PMID: 32105777 DOI: 10.1016/j.cellsig.2020.109589] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 02/21/2020] [Accepted: 02/23/2020] [Indexed: 12/26/2022]
Abstract
A recent break-through paper has revealed for the first time the high-resolution, three-dimensional structure of a mammalian trans-membrane adenylyl cyclase (tmAC) obtained by cryo-electronmicroscopy (cryo-EM). Reporting the structure of adenylyl cyclase 9 (AC9) in complex with activated Gsα, the cryo-EM study revealed that AC9 has three functionally interlinked, yet structurally distinct domains. The array of the twelve transmembrane helices is connected to the cytosolic catalytic core by two helical segments that are stabilized through the formation of a parallel coiled-coil. Surprisingly, in the presence of Gsα, the isoform-specific carboxyl-terminal tail of AC9 occludes the forskolin- as well as the active substrate-sites, resulting in marked autoinhibition of the enzyme. As AC9 has the lowest primary sequence homology with the eight further mammalian tmAC paralogues, it appears to be the best candidate for selective pharmacologic targeting. This is now closer to reality as the structural insight provided by the cryo-EM study indicates that all of the three structural domains are potential targets for bioactive agents. The present paper summarizes for molecular physiologists and pharmacologists what is known about the biological role of AC9, considers the potential modes of physiologic regulation, as well as pharmacologic targeting on the basis of the high-resolution cryo-EM structure. The translational potential of AC9 is considered upon highlighting the current state of genome-wide association screens, and the corresponding experimental evidence. Overall, whilst the high- resolution structure presents unique opportunities for the full understanding of the control of AC9, the data on the biological role of the enzyme and its translational potential are far from complete, and require extensive further study.
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21
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Köfalvi A, Moreno E, Cordomí A, Cai NS, Fernández-Dueñas V, Ferreira SG, Guixà-González R, Sánchez-Soto M, Yano H, Casadó-Anguera V, Cunha RA, Sebastião AM, Ciruela F, Pardo L, Casadó V, Ferré S. Control of glutamate release by complexes of adenosine and cannabinoid receptors. BMC Biol 2020; 18:9. [PMID: 31973708 PMCID: PMC6979073 DOI: 10.1186/s12915-020-0739-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 01/13/2020] [Indexed: 12/20/2022] Open
Abstract
Background It has been hypothesized that heteromers of adenosine A2A receptors (A2AR) and cannabinoid CB1 receptors (CB1R) localized in glutamatergic nerve terminals mediate the integration of adenosine and endocannabinoid signaling involved in the modulation of striatal excitatory neurotransmission. Previous studies have demonstrated the existence of A2AR-CB1R heteromers in artificial cell systems. A dependence of A2AR signaling for the Gi protein-mediated CB1R signaling was described as one of its main biochemical characteristics. However, recent studies have questioned the localization of functionally significant A2AR-CB1R heteromers in striatal glutamatergic terminals. Results Using a peptide-interfering approach combined with biophysical and biochemical techniques in mammalian transfected cells and computational modeling, we could establish a tetrameric quaternary structure of the A2AR-CB1R heterotetramer. This quaternary structure was different to the also tetrameric structure of heteromers of A2AR with adenosine A1 receptors or dopamine D2 receptors, with different heteromeric or homomeric interfaces. The specific quaternary structure of the A2A-CB1R, which depended on intermolecular interactions involving the long C-terminus of the A2AR, determined a significant A2AR and Gs protein-mediated constitutive activation of adenylyl cyclase. Using heteromer-interfering peptides in experiments with striatal glutamatergic terminals, we could then demonstrate the presence of functionally significant A2AR-CB1R heteromers with the same biochemical characteristics of those studied in mammalian transfected cells. First, either an A2AR agonist or an A2AR antagonist allosterically counteracted Gi-mediated CB1R agonist-induced inhibition of depolarization-induced glutamate release. Second, co-application of both an A2AR agonist and an antagonist cancelled each other effects. Finally, a CB1R agonist inhibited glutamate release dependent on a constitutive activation of A2AR by a canonical Gs-Gi antagonistic interaction at the adenylyl cyclase level. Conclusions We demonstrate that the well-established cannabinoid-induced inhibition of striatal glutamate release can mostly be explained by a CB1R-mediated counteraction of the A2AR-mediated constitutive activation of adenylyl cyclase in the A2AR-CB1R heteromer.
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Affiliation(s)
- Attila Köfalvi
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - Estefanía Moreno
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, and Institute of Biomedicine, University of Barcelona, 08028, Barcelona, Spain
| | - Arnau Cordomí
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Ning-Sheng Cai
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Victor Fernández-Dueñas
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Samira G Ferreira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - Ramón Guixà-González
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Marta Sánchez-Soto
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Hideaki Yano
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Verònica Casadó-Anguera
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, and Institute of Biomedicine, University of Barcelona, 08028, Barcelona, Spain
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Ana Maria Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Spain. .,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
| | - Vicent Casadó
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, and Institute of Biomedicine, University of Barcelona, 08028, Barcelona, Spain.
| | - Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA.
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22
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Ferré S, Ciruela F, Casadó V, Pardo L. Oligomerization of G protein-coupled receptors: Still doubted? PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 169:297-321. [DOI: 10.1016/bs.pmbts.2019.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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23
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Identification of Novel Adenylyl Cyclase 5 (AC5) Signaling Networks in D 1 and D 2 Medium Spiny Neurons using Bimolecular Fluorescence Complementation Screening. Cells 2019; 8:cells8111468. [PMID: 31752385 PMCID: PMC6912275 DOI: 10.3390/cells8111468] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 11/15/2019] [Accepted: 11/15/2019] [Indexed: 11/17/2022] Open
Abstract
Adenylyl cyclase type 5 (AC5), as the principal isoform expressed in striatal medium spiny neurons (MSNs), is essential for the integration of both stimulatory and inhibitory midbrain signals that initiate from dopaminergic G protein-coupled receptor (GPCR) activation. The spatial and temporal control of cAMP signaling is dependent upon the composition of local regulatory protein networks. However, there is little understanding of how adenylyl cyclase protein interaction networks adapt to the multifarious pressures of integrating acute versus chronic and inhibitory vs. stimulatory receptor signaling in striatal MSNs. Here, we presented the development of a novel bimolecular fluorescence complementation (BiFC)-based protein-protein interaction screening methodology to further identify and characterize elements important for homeostatic control of dopamine-modulated AC5 signaling in a neuronal model cell line and striatal MSNs. We identified two novel AC5 modulators: the protein phosphatase 2A (PP2A) catalytic subunit (PPP2CB) and the intracellular trafficking associated protein-NSF (N-ethylmaleimide-sensitive factor) attachment protein alpha (NAPA). The effects of genetic knockdown (KD) of each gene were evaluated in several cellular models, including D1- and D2-dopamine receptor-expressing MSNs from CAMPER mice. The knockdown of PPP2CB was associated with a reduction in acute and sensitized adenylyl cyclase activity, implicating PP2A is an important and persistent regulator of adenylyl cyclase activity. In contrast, the effects of NAPA knockdown were more nuanced and appeared to involve an activity-dependent protein interaction network. Taken together, these data represent a novel screening method and workflow for the identification and validation of adenylyl cyclase protein-protein interaction networks under diverse cAMP signaling paradigms.
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24
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van Keulen SC, Narzi D, Rothlisberger U. Association of Both Inhibitory and Stimulatory Gα Subunits Implies Adenylyl Cyclase 5 Deactivation. Biochemistry 2019; 58:4317-4324. [PMID: 31525953 DOI: 10.1021/acs.biochem.9b00662] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Adenylyl cyclase (AC) generates cyclic AMP required for a variety of cellular functions, and its regulation plays a major role in cellular signal transduction in eukaryotes and prokaryotes. All membrane-bound AC isoforms in eukaryotes can be activated by stimulatory G-proteins, but only AC1, AC5, and AC6 can be both stimulated and inhibited by active Gα subunits, Gαs and Gαi, respectively. In principle, these Gαi-sensitive AC isoforms could form both binary and ternary complexes with Gα subunits due to the noncompetitive association of inhibitory and stimulatory Gα. However, the formation and possible catalytic activity of a putative ternary complex have not yet been experimentally confirmed due to its proposed short-lived nature. Here, the catalytic activity of such a ternary complex consisting of apo AC5, stimulatory Gαolf, and inhibitory Gαi1 is investigated via classical molecular dynamics simulations. Trajectories of inhibited and stimulated binary complexes, AC5:Gαi1 and AC5:Gαolf, respectively, as well as Gα-free AC5 were also obtained to compare the sampled AC5 conformation in the ternary complex to those sampled under different Gα conditions. This comparison suggests that association of both Gα subunits results in an AC5 conformation similar to that sampled by the AC5:Gαi1 complex, indicating that the ternary complex mainly samples an inactive conformation.
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Affiliation(s)
- Siri C van Keulen
- Institut des Sciences et Ingénierie Chimiques , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland.,Computational Structural Biology Group, Bijvoet Center for Biomolecular Research , Utrecht University , 3584 CH Utrecht , Netherlands
| | - Daniele Narzi
- Institut des Sciences et Ingénierie Chimiques , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Ursula Rothlisberger
- Institut des Sciences et Ingénierie Chimiques , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
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25
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Bruce NJ, Narzi D, Trpevski D, van Keulen SC, Nair AG, Röthlisberger U, Wade RC, Carloni P, Hellgren Kotaleski J. Regulation of adenylyl cyclase 5 in striatal neurons confers the ability to detect coincident neuromodulatory signals. PLoS Comput Biol 2019; 15:e1007382. [PMID: 31665146 PMCID: PMC6821081 DOI: 10.1371/journal.pcbi.1007382] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 09/05/2019] [Indexed: 02/04/2023] Open
Abstract
Long-term potentiation and depression of synaptic activity in response to stimuli is a key factor in reinforcement learning. Strengthening of the corticostriatal synapses depends on the second messenger cAMP, whose synthesis is catalysed by the enzyme adenylyl cyclase 5 (AC5), which is itself regulated by the stimulatory Gαolf and inhibitory Gαi proteins. AC isoforms have been suggested to act as coincidence detectors, promoting cellular responses only when convergent regulatory signals occur close in time. However, the mechanism for this is currently unclear, and seems to lie in their diverse regulation patterns. Despite attempts to isolate the ternary complex, it is not known if Gαolf and Gαi can bind to AC5 simultaneously, nor what activity the complex would have. Using protein structure-based molecular dynamics simulations, we show that this complex is stable and inactive. These simulations, along with Brownian dynamics simulations to estimate protein association rates constants, constrain a kinetic model that shows that the presence of this ternary inactive complex is crucial for AC5's ability to detect coincident signals, producing a synergistic increase in cAMP. These results reveal some of the prerequisites for corticostriatal synaptic plasticity, and explain recent experimental data on cAMP concentrations following receptor activation. Moreover, they provide insights into the regulatory mechanisms that control signal processing by different AC isoforms.
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Affiliation(s)
- Neil J. Bruce
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Heidelberg, Germany
| | - Daniele Narzi
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Daniel Trpevski
- Science for Life Laboratory, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Siri C. van Keulen
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Department of Computer Science, Stanford University, Stanford, California, United States of America
| | - Anu G. Nair
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Ursula Röthlisberger
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Rebecca C. Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Heidelberg, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Heidelberg, Germany
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Paolo Carloni
- Department of Physics and Department of Neurobiology, RWTH Aachen University,Aachen, Germany
- Institute for Neuroscience and Medicine (INM)-11, Forschungszentrum Jülich, Jülich, Germany
- Institute of Neuroscience and Medicine (INM-9), Forschungszentrum Jülich, Jülich, Germany
- Institute for Advanced Simulation (IAS-5), Forschungszentrum Jülich, Jülich, Germany
| | - Jeanette Hellgren Kotaleski
- Science for Life Laboratory, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Solna, Sweden
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Ferré S, Ciruela F. Functional and Neuroprotective Role of Striatal Adenosine A 2A Receptor Heterotetramers. J Caffeine Adenosine Res 2019; 9:89-97. [PMID: 31559390 PMCID: PMC6761580 DOI: 10.1089/caff.2019.0008] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In the striatum, adenosine A2A receptors (A2AR) are mainly expressed within the soma and dendrites of the striatopallidal neuron. A predominant proportion of these striatal postsynaptic A2AR form part of the macromolecular complexes that include A2AR-dopamine D2 receptor (D2R) heteromers, Golf and Gi/o proteins, and the effector adenylyl cyclase (AC), subtype AC5. The A2AR-D2R heteromers have a tetrameric structure, constituted by A2AR and D2R homomers. By means of reciprocal antagonistic allosteric interactions and antagonistic interactions at the effector level between adenosine and dopamine, the A2AR-D2R heterotetramer-AC5 complex acts an integrative molecular device, which determines a switch between the adenosine-facilitated activation and the dopamine-facilitated inhibition of the striatopallidal neuron. Striatal adenosine also plays an important presynaptic modulatory role, driving the function of corticostriatal terminals. This control is mediated by adenosine A1 receptors (A1R) and A2AR, which establish intermolecular interactions forming A1R-A2AR heterotetramers. Here, we review the functional role of both presynaptic and postsynaptic striatal A2AR heterotetramers as well as their possible neuroprotective role. We hypothesize that alterations in the homomer/heteromer stoichiometry (i.e., increase or decrease in the proportion of A2AR forming homomers or heteromers) are pathogenetically involved in neurological disorders, specifically in Parkinson's disease and restless legs syndrome.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine, IDIBELL, University of Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institute of Neurosciences, University of Barcelona, Barcelona, Spain
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27
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PDE10A mutations help to unwrap the neurobiology of hyperkinetic disorders. Cell Signal 2019; 60:31-38. [PMID: 30951862 DOI: 10.1016/j.cellsig.2019.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/31/2019] [Accepted: 04/01/2019] [Indexed: 12/31/2022]
Abstract
The dual-specific cAMP/cGMP phosphodiesterase PDE10A is exclusively localised to regions of the brain and specific cell types that control crucial brain circuits and behaviours. The downside to this expression pattern is that PDE10A is also positioned to be a key player in pathology when its function is perturbed. The last decade of research has seen a clear role emerge for PDE10A inhibition in modifying behaviours in animal models of psychosis and Huntington's disease. Unfortunately, this has not translated to the human diseases as expected. More recently, a series of families with hyperkinetic movement disorders have been identified with mutations altering the PDE10A protein sequence. As these mutations have been analysed and characterised in other model systems, we are beginning to learn more about PDE10A function and perhaps catch a glimpse into how PDE10A activity could be modified for therapeutic benefit.
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Doyle TB, Hayes MP, Chen DH, Raskind WH, Watts VJ. Functional characterization of AC5 gain-of-function variants: Impact on the molecular basis of ADCY5-related dyskinesia. Biochem Pharmacol 2019; 163:169-177. [PMID: 30772269 DOI: 10.1016/j.bcp.2019.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/05/2019] [Indexed: 12/13/2022]
Abstract
Adenylyl cyclases are key points for the integration of stimulatory and inhibitory G protein-coupled receptor (GPCR) signals. Adenylyl cyclase type 5 (AC5) is highly expressed in striatal medium spiny neurons (MSNs), and is known to play an important role in mediating striatal dopaminergic signaling. Dopaminergic signaling from the D1 expressing MSNs of the direct pathway, as well as the D2 expressing MSNs of the indirect pathway both function through the regulation of AC5 activity, controlling the production of the 2nd messenger cAMP, and subsequently the downstream effectors. Here, we used a newly developed cell line that used Crispr-Cas9 to eliminate the predominant adenylyl cyclase isoforms to more accurately characterize a series of AC5 gain-of-function mutations which have been identified in ADCY5-related dyskinesias. Our results demonstrate that these AC5 mutants exhibit enhanced activity to Gαs-mediated stimulation in both cell and membrane-based assays. We further show that the increased cAMP response at the membrane effectively translates into increased downstream gene transcription in a neuronal model. Subsequent analysis of inhibitory pathways show that the AC5 mutants exhibit significantly reduced inhibition following D2 dopamine receptor activation. Finally, we demonstrate that an adenylyl cyclase "P-site" inhibitor, SQ22536 may represent an effective future therapeutic mechanism by preferentially inhibiting the overactive AC5 gain-of-function mutants.
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Affiliation(s)
- T B Doyle
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, 575 Stadium Mall Drive, West Lafayette, IN, 47907, United States
| | - M P Hayes
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, 575 Stadium Mall Drive, West Lafayette, IN, 47907, United States
| | - D H Chen
- University of Washington, Department of Neurology, Seattle, WA 98195-7720, United States
| | - W H Raskind
- University of Washington, Medicine and Medical Genetics, United States; University of Washington, Psychiatry and Behavioral Sciences, Seattle, WA 98195-7720, United States; Geriatric Research, Education, and Clinical Center, Veterans Administration Puget Sound, Veterans Health Care Center, Seattle, WA 98108, United States
| | - V J Watts
- Purdue University, Medicinal Chemistry and Molecular Pharmacology, 575 Stadium Mall Drive, West Lafayette, IN, 47907, United States; Purdue Institute for Integrative Neuroscience, Hall for Discovery Learning, 207 South Martin Jischke Drive, West Lafayette, IN 47907, United States; Purdue Institute for Drug Discovery, 720 Clinic Drive, West Lafayette, IN 47907, United States.
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29
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Baldwin TA, Li Y, Brand CS, Watts VJ, Dessauer CW. Insights into the Regulatory Properties of Human Adenylyl Cyclase Type 9. Mol Pharmacol 2019; 95:349-360. [PMID: 30696718 DOI: 10.1124/mol.118.114595] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 01/23/2019] [Indexed: 11/22/2022] Open
Abstract
Membrane-bound adenylyl cyclase (AC) isoforms have distinct regulatory mechanisms that contribute to their signaling specificity and physiologic roles. Although insight into the physiologic relevance of AC9 has progressed, the understanding of AC9 regulation is muddled with conflicting studies. Currently, modes of AC9 regulation include stimulation by Gαs, protein kinase C (PKC) βII, or calcium-calmodulin kinase II (CaMKII) and inhibition by Gαi/o, novel PKC isoforms, or calcium-calcineurin. Conversely, the original cloning of human AC9 reported that AC9 is insensitive to Gαi inhibition. The purpose of our study was to clarify which proposed regulators of AC9 act directly or indirectly, particularly with respect to Gαi/o. The proposed regulators, including G proteins (Gαs, Gαi, Gαo, Gβγ), protein kinases (PKCβII, CaMKII), and forskolin, were systematically evaluated using classic in vitro AC assays and cell-based cAMP accumulation assays in COS-7 cells. Our studies show that AC9 is directly regulated by Gαs with weak conditional activation by forskolin; other modes of proposed regulation either occur indirectly or possibly require additional scaffolding proteins to facilitate regulation. We also show that AC9 contributes to basal cAMP production; knockdown or knockout of endogenous AC9 reduces basal AC activity in COS-7 cells and splenocytes. Importantly, although AC9 is not directly inhibited by Gαi/o, it can heterodimerize with Gαi/o-regulated isoforms, AC5 and AC6.
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Affiliation(s)
- Tanya A Baldwin
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas (T.A.B., Y.L., C.S.B., C.W.D.); and Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana (V.J.W.)
| | - Yong Li
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas (T.A.B., Y.L., C.S.B., C.W.D.); and Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana (V.J.W.)
| | - Cameron S Brand
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas (T.A.B., Y.L., C.S.B., C.W.D.); and Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana (V.J.W.)
| | - Val J Watts
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas (T.A.B., Y.L., C.S.B., C.W.D.); and Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana (V.J.W.)
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas (T.A.B., Y.L., C.S.B., C.W.D.); and Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana (V.J.W.)
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30
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Ferré S, Díaz-Ríos M, Salamone JD, Prediger RD. New Developments on the Adenosine Mechanisms of the Central Effects of Caffeine and Their Implications for Neuropsychiatric Disorders. J Caffeine Adenosine Res 2018; 8:121-131. [PMID: 30596206 PMCID: PMC6306650 DOI: 10.1089/caff.2018.0017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recent studies on interactions between striatal adenosine and dopamine and one of its main targets, the adenosine A2A receptor–dopamine D2 receptor (A2AR–D2R) heteromer, have provided a better understanding of the mechanisms involved in the psychostimulant effects of caffeine and have brought forward new data on the mechanisms of operation of classical orthosteric ligands within G protein-coupled receptor heteromers. The striatal A2AR–D2R heteromer has a tetrameric structure and forms part of a signaling complex that includes a Gs and a Gi protein and the effector adenyl cyclase (subtype AC5). Another target of caffeine, the adenosine A1 receptor–dopamine D1 receptor (A1R–D1R) heteromer, seems to have a very similar structure. Initially suggested to be localized in the striatum, the A1R–D1R heteromer has now been identified in the spinal motoneuron and shown to mediate the spinally generated caffeine-induced locomotion. In this study, we review the recently discovered properties of A2AR–D2R and A1R–D1R heteromers. Our studies demonstrate that these complexes are a necessary condition to sustain the canonical antagonistic interaction between a Gs-coupled receptor (A2AR or D1R) and a Gi-coupled receptor (D2R or A1R) at the adenylyl cyclase level, which constitutes a new concept in the field of G protein-coupled receptor physiology and pharmacology. A2AR antagonists targeting the striatal A2AR–D2R heteromer are already being considered as therapeutic agents in Parkinson's disease. In this study, we review the preclinical evidence that indicates that caffeine and A2AR antagonists could be used to treat the motivational symptoms of depression and attention-deficit/hyperactivity disorder, while A1R antagonists selectively targeting the spinal A1R–D1R heteromer could be used in the recovery of spinal cord injury.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland
| | - Manuel Díaz-Ríos
- Department of Anatomy and Neurobiology, Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | - John D Salamone
- Department of Psychological Sciences, University of Connecticut, Storrs, Connecticut
| | - Rui Daniel Prediger
- Department of Pharmacology, Federal University of Santa Catarina, Florianópolis, Brazil
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31
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Tewson P, Martinka S, Shaner N, Berlot C, Quinn AM, Hughes T. Assay for Detecting Gαi-Mediated Decreases in cAMP in Living Cells. SLAS DISCOVERY 2018; 23:898-906. [PMID: 29991302 DOI: 10.1177/2472555218786238] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cell-based assays to detect Gαi signaling are often indirect, frequently involve complex pharmacological interventions, and are usually blind to the kinetics of the signaling. Our goal was to develop a simple, direct measure of Gαi signaling in living cells. We previously reported our fluorescent cADDis assay and showed that it reliably detects Gαs-mediated increases in cAMP levels. Agonists that stimulate a Gs-coupled receptor produce changes in the intensity of bright green or red fluorescent protein sensors that can be followed over time using automated fluorescence plate readers or fluorescence imaging systems. Since the cADDis sensors can monitor Gαs-mediated increases in adenylyl cyclase activity, in theory they should also be capable of detecting Gαi-mediated decreases. Here we apply our green fluorescent cADDis sensor to the detection of Gαi-mediated inhibition of adenylyl cyclase activity. We validated and optimized the assay in living HEK 293T cells using several known Gαi-coupled receptors and agonists, and we report robust Z' statistics and consistent EC50 responses.
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Affiliation(s)
| | | | - Nathan Shaner
- 2 Department of Photobiology and Bioimaging, The Scintillon Institute, San Diego, CA, USA
| | | | | | - Thomas Hughes
- 1 Montana Molecular, Bozeman, MT, USA.,3 Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT, USA
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32
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Wiggins SV, Steegborn C, Levin LR, Buck J. Pharmacological modulation of the CO 2/HCO 3-/pH-, calcium-, and ATP-sensing soluble adenylyl cyclase. Pharmacol Ther 2018; 190:173-186. [PMID: 29807057 DOI: 10.1016/j.pharmthera.2018.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cyclic AMP (cAMP), the prototypical second messenger, has been implicated in a wide variety of (often opposing) physiological processes. It simultaneously mediates multiple, diverse processes, often within a single cell, by acting locally within independently-regulated and spatially-restricted microdomains. Within each microdomain, the level of cAMP will be dependent upon the balance between its synthesis by adenylyl cyclases and its degradation by phosphodiesterases (PDEs). In mammalian cells, there are many PDE isoforms and two types of adenylyl cyclases; the G protein regulated transmembrane adenylyl cyclases (tmACs) and the CO2/HCO3-/pH-, calcium-, and ATP-sensing soluble adenylyl cyclase (sAC). Discriminating the roles of individual cyclic nucleotide microdomains requires pharmacological modulators selective for the various PDEs and/or adenylyl cyclases. Such tools present an opportunity to develop therapeutics specifically targeted to individual cAMP dependent pathways. The pharmacological modulators of tmACs have recently been reviewed, and in this review, we describe the current status of pharmacological tools available for studying sAC.
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Affiliation(s)
- Shakarr V Wiggins
- Graduate Program in Neuroscience, Weill Cornell Medicine, New York, NY 10065, United States
| | - Clemens Steegborn
- Department of Biochemistry, University of Bayreuth, 95440 Bayreuth, Germany
| | - Lonny R Levin
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10065, United States.
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10065, United States
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33
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A molecular dynamics study of adenylyl cyclase: The impact of ATP and G-protein binding. PLoS One 2018; 13:e0196207. [PMID: 29694437 PMCID: PMC5918993 DOI: 10.1371/journal.pone.0196207] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 04/09/2018] [Indexed: 12/26/2022] Open
Abstract
Adenylyl cyclases (ACs) catalyze the biosynthesis of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP) and play an important role in many signal transduction pathways. The enzymatic activity of ACs is carefully controlled by a variety of molecules, including G-protein subunits that can both stimulate and inhibit cAMP production. Using homology models developed from existing structural data, we have carried out all-atom, microsecond-scale molecular dynamics simulations on the AC5 isoform of adenylyl cyclase and on its complexes with ATP and with the stimulatory G-protein subunit Gsα. The results show that both ATP and Gsα binding have significant effects on the structure and flexibility of adenylyl cyclase. New data on ATP bound to AC5 in the absence of Gsα notably help to explain how Gsα binding enhances enzyme activity and could aid product release. Simulations also suggest a possible coupling between ATP binding and interactions with the inhibitory G-protein subunit Gαi.
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34
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Robichaux WG, Cheng X. Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development. Physiol Rev 2018; 98:919-1053. [PMID: 29537337 PMCID: PMC6050347 DOI: 10.1152/physrev.00025.2017] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.
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Affiliation(s)
- William G Robichaux
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
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35
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Evidence for functional pre-coupled complexes of receptor heteromers and adenylyl cyclase. Nat Commun 2018; 9:1242. [PMID: 29593213 PMCID: PMC5871782 DOI: 10.1038/s41467-018-03522-3] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 02/21/2018] [Indexed: 01/13/2023] Open
Abstract
G protein-coupled receptors (GPCRs), G proteins and adenylyl cyclase (AC) comprise one of the most studied transmembrane cell signaling pathways. However, it is unknown whether the ligand-dependent interactions between these signaling molecules are based on random collisions or the rearrangement of pre-coupled elements in a macromolecular complex. Furthermore, it remains controversial whether a GPCR homodimer coupled to a single heterotrimeric G protein constitutes a common functional unit. Using a peptide-based approach, we here report evidence for the existence of functional pre-coupled complexes of heteromers of adenosine A2A receptor and dopamine D2 receptor homodimers coupled to their cognate Gs and Gi proteins and to subtype 5 AC. We also demonstrate that this macromolecular complex provides the necessary frame for the canonical Gs-Gi interactions at the AC level, sustaining the ability of a Gi-coupled GPCR to counteract AC activation mediated by a Gs-coupled GPCR. It is unclear whether GPCRs, G proteins and adenylyl cyclase (AC) associate through random collisions or defined pre-coupling mechanisms. Using a peptide-based approach, the authors show that heteromers of adenosine A2A and dopamine D2 receptors form pre-coupled complexes with their cognate G proteins and AC5.
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36
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Function of Adenylyl Cyclase in Heart: the AKAP Connection. J Cardiovasc Dev Dis 2018; 5:jcdd5010002. [PMID: 29367580 PMCID: PMC5872350 DOI: 10.3390/jcdd5010002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/09/2018] [Accepted: 01/11/2018] [Indexed: 12/13/2022] Open
Abstract
Cyclic adenosine monophosphate (cAMP), synthesized by adenylyl cyclase (AC), is a universal second messenger that regulates various aspects of cardiac physiology from contraction rate to the initiation of cardioprotective stress response pathways. Local pools of cAMP are maintained by macromolecular complexes formed by A-kinase anchoring proteins (AKAPs). AKAPs facilitate control by bringing together regulators of the cAMP pathway including G-protein-coupled receptors, ACs, and downstream effectors of cAMP to finely tune signaling. This review will summarize the distinct roles of AC isoforms in cardiac function and how interactions with AKAPs facilitate AC function, highlighting newly appreciated roles for lesser abundant AC isoforms.
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37
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van Keulen SC, Rothlisberger U. Exploring the inhibition mechanism of adenylyl cyclase type 5 by n-terminal myristoylated Gαi1. PLoS Comput Biol 2017; 13:e1005673. [PMID: 28892485 PMCID: PMC5608429 DOI: 10.1371/journal.pcbi.1005673] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 09/21/2017] [Accepted: 06/26/2017] [Indexed: 11/18/2022] Open
Abstract
Adenylyl cyclase (AC) is an important messenger involved in G-protein-coupled-receptor signal transduction pathways, which is a well-known target for drug development. AC is regulated by activated stimulatory (Gαs) and inhibitory (Gαi) G proteins in the cytosol. Although experimental studies have shown that these Gα subunits can stimulate or inhibit AC's function in a non-competitive way, it is not well understood what the difference is in their mode of action as both Gα subunits appear structurally very similar in a non-lipidated state. However, a significant difference between Gαs and Gαi is that while Gαs does not require any lipidation in order to stimulate AC, N-terminal myristoylation is crucial for Gαi's inhibitory function as AC is not inhibited by non-myristoylated Gαi. At present, only the conformation of the complex including Gαs and AC has been resolved via X-ray crystallography. Therefore, understanding the interaction between Gαi and AC is important as it will provide more insight into the unknown mechanism of AC regulation. This study demonstrates via classical molecular dynamics simulations that the myristoylated Gαi1 structure is able to interact with apo adenylyl cyclase type 5 in a way that causes inhibition of the catalytic function of the enzyme, suggesting that Gα lipidation could play a crucial role in AC regulation and in regulating G protein function by affecting Gαi's active conformation.
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Affiliation(s)
- Siri Camee van Keulen
- Institut des Sciences et Ingénierie Chimiques, École Polytechnicque Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ursula Rothlisberger
- Institut des Sciences et Ingénierie Chimiques, École Polytechnicque Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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38
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Dessauer CW, Watts VJ, Ostrom RS, Conti M, Dove S, Seifert R. International Union of Basic and Clinical Pharmacology. CI. Structures and Small Molecule Modulators of Mammalian Adenylyl Cyclases. Pharmacol Rev 2017; 69:93-139. [PMID: 28255005 PMCID: PMC5394921 DOI: 10.1124/pr.116.013078] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adenylyl cyclases (ACs) generate the second messenger cAMP from ATP. Mammalian cells express nine transmembrane AC (mAC) isoforms (AC1-9) and a soluble AC (sAC, also referred to as AC10). This review will largely focus on mACs. mACs are activated by the G-protein Gαs and regulated by multiple mechanisms. mACs are differentially expressed in tissues and regulate numerous and diverse cell functions. mACs localize in distinct membrane compartments and form signaling complexes. sAC is activated by bicarbonate with physiologic roles first described in testis. Crystal structures of the catalytic core of a hybrid mAC and sAC are available. These structures provide detailed insights into the catalytic mechanism and constitute the basis for the development of isoform-selective activators and inhibitors. Although potent competitive and noncompetitive mAC inhibitors are available, it is challenging to obtain compounds with high isoform selectivity due to the conservation of the catalytic core. Accordingly, caution must be exerted with the interpretation of intact-cell studies. The development of isoform-selective activators, the plant diterpene forskolin being the starting compound, has been equally challenging. There is no known endogenous ligand for the forskolin binding site. Recently, development of selective sAC inhibitors was reported. An emerging field is the association of AC gene polymorphisms with human diseases. For example, mutations in the AC5 gene (ADCY5) cause hyperkinetic extrapyramidal motor disorders. Overall, in contrast to the guanylyl cyclase field, our understanding of the (patho)physiology of AC isoforms and the development of clinically useful drugs targeting ACs is still in its infancy.
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Affiliation(s)
- Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Val J Watts
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Rennolds S Ostrom
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Marco Conti
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Stefan Dove
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
| | - Roland Seifert
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Sciences Center at Houston, Houston, Texas (C.W.D.); Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana (V.J.W.); Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (R.S.O.); Center for Reproductive Sciences, University of California San Francisco, San Francisco, California (M.C.); Institute of Pharmacy, University of Regensburg, Regensburg, Germany (S.D.); and Institute of Pharmacology, Hannover Medical School, Hannover, Germany (R.S.)
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39
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Ziegler M, Bassler J, Beltz S, Schultz A, Lupas AN, Schultz JE. Characterization of a novel signal transducer element intrinsic to class IIIa/b adenylate cyclases and guanylate cyclases. FEBS J 2017; 284:1204-1217. [PMID: 28222489 DOI: 10.1111/febs.14047] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 01/09/2017] [Accepted: 02/17/2017] [Indexed: 11/28/2022]
Abstract
Adenylate cyclases (ACs) are signaling proteins that produce the second messenger cAMP. Class III ACs comprise four groups (class IIIa-d) of which class IIIa and IIIb ACs have been identified in bacteria and eukaryotes. Many class IIIa ACs are anchored to membranes via hexahelical domains. In eukaryotic ACs, membrane anchors are well conserved, suggesting that this region possesses important functional characteristics that are as yet unknown. To address this question, we replaced the hexahelical membrane anchor of the mycobacterial AC Rv1625c with the hexahelical quorum-sensing receptor from Legionella, LqsS. Using this chimera, we identified a novel 19-amino-acid cyclase transducer element (CTE) located N-terminally to the catalytic domain that links receptor stimulation to effector activation. Coupling of the receptor to the AC was possible at several positions distal to the membrane exit, resulting in stimulatory or inhibitory responses to the ligand Legionella autoinducer-1. In contrast, on the AC effector side functional coupling was only successful when starting with the CTE. Bioinformatics approaches established that distinct CTEs are widely present in class IIIa and IIIb ACs and in vertebrate guanylate cyclases. The data suggest that membrane-delimited receiver domains transduce regulatory signals to the downstream catalytic domains in an engineered AC model system. This may suggest a previously unknown mechanism for cellular cAMP regulation.
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Affiliation(s)
- Miriam Ziegler
- Pharmazeutisches Institut der Universität Tübingen, Germany
| | - Jens Bassler
- Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany
| | | | - Anita Schultz
- Pharmazeutisches Institut der Universität Tübingen, Germany
| | - Andrei N Lupas
- Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany
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van Keulen SC, Rothlisberger U. Effect of N-Terminal Myristoylation on the Active Conformation of Gα i1-GTP. Biochemistry 2016; 56:271-280. [PMID: 27936598 DOI: 10.1021/acs.biochem.6b00388] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
G proteins are part of the G-protein-coupled receptor (GPCR) signal transduction cascade in which they transfer a signal from the membrane-embedded GPCR to other proteins in the cell. In the case of the inhibitory G-protein heterotrimer, permanent N-terminal myristoylation can transiently localize the Gαi subunit at the membrane as well as crucially influence Gαi's function in the GTP-bound conformation. The attachment of lipids to proteins is known to be essential for membrane trafficking; however, our results suggest that lipidation is also important for protein-protein interactions during signal transduction. Here we investigate the effect of myristoylation on the structure and dynamics of soluble Gαi1 and its possible implication for signal transduction. A 2 μs classical molecular dynamics simulation of a myristoylated Gαi1-GTP complex suggests that the myristoyl-induced conformational changes of the switch II and alpha helical domains create new possibilities for protein-protein interactions and emphasize the importance of permanent lipid attachment for the conformation and functional tunability of signaling proteins.
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Affiliation(s)
- Siri C van Keulen
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Ursula Rothlisberger
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
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41
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Tong R, Wade RC, Bruce NJ. Comparative electrostatic analysis of adenylyl cyclase for isoform dependent regulation properties. Proteins 2016; 84:1844-1858. [PMID: 27667304 DOI: 10.1002/prot.25167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/29/2016] [Accepted: 09/06/2016] [Indexed: 01/26/2023]
Abstract
The enzyme adenylyl cyclase (AC) plays a pivotal role in a variety of signal transduction pathways inside the cell, where it catalyzes the cyclization of adenosine triphosphate (ATP) into the second-messenger cyclic adenosine monophosphate (cAMP). Among other roles, AC regulates processes involved in neural plasticity, innervation of smooth muscles of the heart and the endocrine system of the pancreas. The functional diversity of AC is manifested in its different isoforms, each having a specific regulation pattern. There is an increasing amount of data available concerning the regulatory properties of AC isoforms, however little is known about the interactions on a structural level. Here, we conducted a comparative electrostatic analysis of the catalytic domains of all nine transmembrane AC isoforms with the aim of detecting, verifying and predicting the binding sites of molecular regulators on AC. The results provide support for the positioning of the binding site of the inhibitory protein Gi α at a pseudo-symmetric position to the stimulatory Gs α binding site. They also provide a structural interpretation of the Gβγ interaction with ACs 2, 4, and 7 and suggest a new binding site for RGS2. Comparison of the small molecule binding sites on AC shows that overall they have high electrostatic similarity, but regions of electrostatic differences are identified. These could provide a basis for the development of novel compounds with isoform-specific modulatory effects on AC. Proteins 2016; 84:1844-1858. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Rudi Tong
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany.,Institute of Pharmacy and Molecular Biotechnology (IPMB) Heidelberg University, Im Neuenheimer Feld 364, 69120, Heidelberg, Germany
| | - Rebecca C Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany.,Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR) Heidelberg University, Im Neuenheimer Feld 368, 69120, Heidelberg, Germany
| | - Neil J Bruce
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany
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Sunahara RK, Insel PA. The Molecular Pharmacology of G Protein Signaling Then and Now: A Tribute to Alfred G. Gilman. Mol Pharmacol 2016; 89:585-92. [PMID: 26984025 PMCID: PMC11037445 DOI: 10.1124/mol.116.104216] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 03/14/2016] [Indexed: 11/22/2022] Open
Abstract
The recent, unfortunate death of Alfred G. ("Al") Gilman, M.D., Ph.D., represents a sad signpost for an era spanning over 40 years in molecular pharmacology. Gilman's discoveries, influence, and persona were dominant forces in research and training in pharmacology. Here, we review the progression of ideas and knowledge that spawned early work by Gilman and collaborators (among them, one of the authors) and later efforts (including those of the other author) that have recently yielded a comprehensive and precise structural understanding of fundamental topics in pharmacology: the binding of ligands to G protein-coupled receptors (GPCRs) and the interaction of GPCRs with heterotrimeric G proteins and effector molecules. Those data provide new and important insights into the molecular basis that underlies affinity and efficacy, two of the most important features of drug action, which represent the latest chapter in the saga that Al Gilman's work helped launch.
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Affiliation(s)
- Roger K Sunahara
- Department of Pharmacology (R.K.S., P.A.I.) and Department of Medicine (P.A.I.), University of California, San Diego, La Jolla, California
| | - Paul A Insel
- Department of Pharmacology (R.K.S., P.A.I.) and Department of Medicine (P.A.I.), University of California, San Diego, La Jolla, California
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Brand CS, Sadana R, Malik S, Smrcka AV, Dessauer CW. Adenylyl Cyclase 5 Regulation by Gβγ Involves Isoform-Specific Use of Multiple Interaction Sites. Mol Pharmacol 2015. [PMID: 26206488 DOI: 10.1124/mol.115.099556] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Adenylyl cyclase (AC) converts ATP into cyclic AMP (cAMP), an important second messenger in cell signaling. Heterotrimeric G proteins and other regulators are important for control of AC activity. Depending on the AC isoform, Gβγ subunits can either conditionally stimulate or inhibit cAMP synthesis. We previously showed that the Gαs-βγ heterotrimer binds to the N terminus (NT) of type 5 AC (AC5). We now show that Gβγ binds to the NT of a wide variety of AC isoforms. We hypothesized that Gβγ/AC5 interactions involving inactive heterotrimer and Gβγ stimulation of AC5 were separable events. Mutations of the Gβγ "hotspot" show that this site is necessary for AC5 stimulation but not for interactions with the first 198 aa of AC5NT, which is a G protein scaffolding site. This contrasts with AC6, where the Gβγ hotspot is required for both interactions with AC6NT and for stimulation of AC6. Additionally, the SIGK hotspot peptide disrupts Gβγ regulation of AC isoforms 1, 2, and 6, but not AC5. Gβγ also binds the C1/C2 catalytic domains of AC5 and AC6. Finally, cellular interactions with full-length AC5 depend on multiple sites on Gβγ. This suggests an isoform-specific mechanism in which bound Gβγ at the AC5NT is ideally situated for spatiotemporal control of AC5. We propose Gβγ regulation of AC involves multiple binding events, and the role of the AC NT for mechanisms of regulation by heterotrimeric G protein subunits is isoform-specific.
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Affiliation(s)
- Cameron S Brand
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.)
| | - Rachna Sadana
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.)
| | - Sundeep Malik
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.)
| | - Alan V Smrcka
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.)
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.)
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Dynamics of adenylate cyclase regulation via heterotrimeric G-proteins. Biochem Soc Trans 2015; 42:239-43. [PMID: 24646224 DOI: 10.1042/bst20130280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A wide variety of G-protein-coupled receptors either activate or inhibit ACs (adenylate cyclases), thereby regulating cellular cAMP levels and consequently inducing proper physiological responses. Stimulatory and inhibitory G-proteins interact directly with ACs, whereas G(q)-coupled receptors exert their effects primarily via Ca2+. Using the FRET-based cAMP sensor Epac1 (exchange protein directly activated by cAMP 1)-cAMPS (adenosine 3',5'-cyclic monophosphorothioate), we studied cAMP levels in single living VSMCs (vascular smooth muscle cells) or HUVECs (human umbilical vein endothelial cells) with subsecond temporal resolution. Stimulation of purinergic (VSMCs) or thrombin (HUVECs) receptors rapidly decreased cAMP levels in the presence of the β-adrenergic agonist isoprenaline via a rise in Ca2+ and subsequent inhibition of AC5 and AC6. Specifically in HUVECs, we observed that, in the continuous presence of thrombin, cAMP levels climbed slowly after the initial decline with a delay of a little less than 1 min. The underlying mechanism includes phospholipase A2 activity and cyclo-oxygenase-mediated synthesis of prostaglandins. We studied further the dynamics of the inhibition of ACs via G(i)-proteins utilizing FRET imaging to resolve interactions between fluorescently labelled G(i)-proteins and AC5. FRET between Gα(i1) and AC5 developed at much lower concentration of agonist compared with the overall G(i)-protein activity. We found the dissociation of Gα(i1) subunits and AC5 to occur slower than the G(i)-protein deactivation. This led us to the conclusion that AC5, by binding active Gα(i1), interferes with G-protein deactivation and reassembly and thereby might sensitize its own regulation.
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Bodmann EL, Wolters V, Bünemann M. Dynamics of G protein effector interactions and their impact on timing and sensitivity of G protein-mediated signal transduction. Eur J Cell Biol 2015; 94:415-9. [PMID: 26074197 DOI: 10.1016/j.ejcb.2015.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
G protein coupled receptors regulate numerous cellular functions primarily via coupling to heterotrimeric G proteins and subsequent regulation of effector proteins such as ion channels, enzymes or GTP exchange factors for small G proteins. The dynamics of interactions between G protein subunits and effectors have been difficult to study particularly in a cellular context. The introduction of Förster resonance energy transfer methods into the field of GPCR research led to interesting insights into the temporal patterns of interactions between G protein subunits and their effectors. In this review we specifically focus on the interaction of Gαi subunits with adenylyl cyclases and of Gαq subunits with p63RhoGEF or G protein coupled receptor kinases type 2. Comparing the dynamics of these interactions revealed remarkable differences between different G protein effectors regarding the ability to be modulated by members of the regulator of G protein signalling protein family as well as the sensitivity towards receptor activation.
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Affiliation(s)
- Eva-Lisa Bodmann
- Institute for Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Valerie Wolters
- Institute for Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Moritz Bünemann
- Institute for Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany.
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Reddy GR, Subramanian H, Birk A, Milde M, Nikolaev VO, Bünemann M. Adenylyl cyclases 5 and 6 underlie PIP3-dependent regulation. FASEB J 2015; 29:3458-71. [PMID: 25931510 DOI: 10.1096/fj.14-268466] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/21/2015] [Indexed: 11/11/2022]
Abstract
Many different neurotransmitters and hormones control intracellular signaling by regulating the production of the second messenger cAMP. The function of the broadly expressed adenylyl cyclases (ACs) 5 and 6 is regulated by either stimulatory or inhibitory G proteins. By analyzing a well-known rebound stimulation phenomenon after withdrawal of Gi protein in atrial myocytes, we discovered that AC5 and -6 are tightly regulated by the second messenger PIP3. By monitoring cAMP levels in real time by means of Förster resonance energy transfer (FRET)-based biosensors, we reproduced the rebound stimulation in a heterologous expression system specifically for AC5 or -6. Strikingly, this cAMP rebound stimulation was completely blocked by the PI3K inhibitor wortmannin, both in atrial myocytes and in transfected human embryonic kidney cells. Similar effects were observed by heterologous expression of the PIP3 phosphatase and tensin homolog (PTEN). However, general kinase inhibitors or inhibitors of Akt had no effect, suggesting a PIP3-dependent mechanism. These findings demonstrate the existence of a novel general pathway for regulation of AC5 and -6 activity via PIP3 that leads to pronounced alterations of cytosolic cAMP levels.
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Affiliation(s)
- Gopireddy Raghavender Reddy
- *Faculty of Pharmacy, Philipps University, Marburg, Marburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Interfakultäres Institut für Biochemie, University of Tübingen, Tübingen, Germany
| | - Hariharan Subramanian
- *Faculty of Pharmacy, Philipps University, Marburg, Marburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Interfakultäres Institut für Biochemie, University of Tübingen, Tübingen, Germany
| | - Alexandra Birk
- *Faculty of Pharmacy, Philipps University, Marburg, Marburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Interfakultäres Institut für Biochemie, University of Tübingen, Tübingen, Germany
| | - Markus Milde
- *Faculty of Pharmacy, Philipps University, Marburg, Marburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Interfakultäres Institut für Biochemie, University of Tübingen, Tübingen, Germany
| | - Viacheslav O Nikolaev
- *Faculty of Pharmacy, Philipps University, Marburg, Marburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Interfakultäres Institut für Biochemie, University of Tübingen, Tübingen, Germany
| | - Moritz Bünemann
- *Faculty of Pharmacy, Philipps University, Marburg, Marburg, Germany; Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Interfakultäres Institut für Biochemie, University of Tübingen, Tübingen, Germany
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Ferré S. The GPCR heterotetramer: challenging classical pharmacology. Trends Pharmacol Sci 2015; 36:145-52. [PMID: 25704194 PMCID: PMC4357316 DOI: 10.1016/j.tips.2015.01.002] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 01/15/2015] [Accepted: 01/20/2015] [Indexed: 01/09/2023]
Abstract
Two concepts are gaining increasing acceptance in G protein-coupled receptor (GPCR) pharmacology: (i) pre-coupling of GPCRs with their preferred signaling molecules, and (ii) GPCR oligomerization. This is begging for the introduction of new models such as GPCR oligomer-containing signaling complexes with GPCR homodimers as functional building blocks. This model favors the formation of GPCR heterotetramers - heteromers of homodimers coupled to their cognate G protein. The GPCR heterotetramer offers an optimal framework for a canonical antagonistic interaction between activated Gs and Gi proteins, which can simultaneously bind to their respective preferred receptors and to adenylyl cyclase (AC) catalytic units. This review addresses the current evidence for pre-coupling of the various specific components that provide the very elaborate signaling machinery exemplified by the Gs-Gi-AC-coupled GPCR heterotetramer.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health (NIH), Triad Technology Building, 333 Cassell Drive, Baltimore, MD 21224, USA.
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Kahanovitch U, Tsemakhovich V, Berlin S, Rubinstein M, Styr B, Castel R, Peleg S, Tabak G, Dessauer CW, Ivanina T, Dascal N. Recruitment of Gβγ controls the basal activity of G-protein coupled inwardly rectifying potassium (GIRK) channels: crucial role of distal C terminus of GIRK1. J Physiol 2014; 592:5373-90. [PMID: 25384780 DOI: 10.1113/jphysiol.2014.283218] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The G-protein coupled inwardly rectifying potassium (GIRK, or Kir3) channels are important mediators of inhibitory neurotransmission via activation of G-protein coupled receptors (GPCRs). GIRK channels are tetramers comprising combinations of subunits (GIRK1-4), activated by direct binding of the Gβγ subunit of Gi/o proteins. Heterologously expressed GIRK1/2 exhibit high, Gβγ-dependent basal currents (Ibasal) and a modest activation by GPCR or coexpressed Gβγ. Inversely, the GIRK2 homotetramers exhibit low Ibasal and strong activation by Gβγ. The high Ibasal of GIRK1 seems to be associated with its unique distal C terminus (G1-dCT), which is not present in the other subunits. We investigated the role of G1-dCT using electrophysiological and fluorescence assays in Xenopus laevis oocytes and protein interaction assays. We show that expression of GIRK1/2 increases the plasma membrane level of coexpressed Gβγ (a phenomenon we term 'Gβγ recruitment') but not of coexpressed Gαi3. All GIRK1-containing channels, but not GIRK2 homomers, recruited Gβγ to the plasma membrane. In biochemical assays, truncation of G1-dCT reduces the binding between the cytosolic parts of GIRK1 and Gβγ, but not Gαi3. Nevertheless, the truncation of G1-dCT does not impair activation by Gβγ. In fluorescently labelled homotetrameric GIRK1 channels and in the heterotetrameric GIRK1/2 channel, the truncation of G1-dCT abolishes Gβγ recruitment and decreases Ibasal. Thus, we conclude that G1-dCT carries an essential role in Gβγ recruitment by GIRK1 and, consequently, in determining its high basal activity. Our results indicate that G1-dCT is a crucial part of a Gβγ anchoring site of GIRK1-containing channels, spatially and functionally distinct from the site of channel activation by Gβγ.
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Affiliation(s)
- Uri Kahanovitch
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Vladimir Tsemakhovich
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shai Berlin
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Moran Rubinstein
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Boaz Styr
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ruth Castel
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Sagit Peleg
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Galit Tabak
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA
| | - Tatiana Ivanina
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nathan Dascal
- Department of Physiology and Pharmacology and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
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A functional genome-wide in vivo screen identifies new regulators of signalling pathways during early Xenopus embryogenesis. PLoS One 2013; 8:e79469. [PMID: 24244509 PMCID: PMC3828355 DOI: 10.1371/journal.pone.0079469] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 10/01/2013] [Indexed: 01/09/2023] Open
Abstract
Embryonic development requires exquisite regulation of several essential processes, such as patterning of tissues and organs, cell fate decisions, and morphogenesis. Intriguingly, these diverse processes are controlled by only a handful of signalling pathways, and mis-regulation in one or more of these pathways may result in a variety of congenital defects and diseases. Consequently, investigating how these signalling pathways are regulated at the molecular level is essential to understanding the mechanisms underlying vertebrate embryogenesis, as well as developing treatments for human diseases. Here, we designed and performed a large-scale gain-of-function screen in Xenopus embryos aimed at identifying new regulators of MAPK/Erk, PI3K/Akt, BMP, and TGF-β/Nodal signalling pathways. Our gain-of-function screen is based on the identification of gene products that alter the phosphorylation state of key signalling molecules, which report the activation state of the pathways. In total, we have identified 20 new molecules that regulate the activity of one or more signalling pathways during early Xenopus development. This is the first time that such a functional screen has been performed, and the findings pave the way toward a more comprehensive understanding of the molecular mechanisms regulating the activity of important signalling pathways under normal and pathological conditions.
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Dynamics of Gαi1 interaction with type 5 adenylate cyclase reveal the molecular basis for high sensitivity of Gi-mediated inhibition of cAMP production. Biochem J 2013; 454:515-23. [PMID: 23841650 DOI: 10.1042/bj20130554] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Many physiological and pathophysiological processes are regulated by cAMP. Different therapies directly or indirectly influence the cellular concentration of this second messenger. A wide variety of receptors either activates or inhibits adenylate cyclases in order to induce proper physiological responses. A key event in this signalling system is the direct and dynamic interaction of Gαi1 subunits with adenylate cyclases. We established a FRET-based assay between G-protein subunits and AC5 (type 5 adenylate cyclase) and monitored receptor-stimulated interactions between Gαi1 and AC5 in single intact cells with high temporal resolution. We observed that FRET between Gαi1 and AC5 developed at much lower concentration of agonist compared with the overall Gi-protein activity resulting in a left-shift of the concentration-response curve by approximately one order of magnitude. Furthermore, Gi1-protein-mediated attenuation of AC5-dependent increases in cAMP occurred at comparable low concentrations of agonist. On analysing the dynamics we found the dissociation of the Gαi1 subunits and AC5 to occur significantly slower than the G-protein deactivation and to be insensitive to RGS4 (regulator of G-protein signalling type 4) expression. This led us to the conclusion that AC5, by binding active Gαi1, interferes with G-protein deactivation and reassembly and thereby might sensitize its own regulation.
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