1
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Yang W, Mei FC, Lin W, White MA, Li L, Li Y, Pan S, Cheng X. Protein SUMOylation promotes cAMP-independent EPAC1 activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.574738. [PMID: 38260470 PMCID: PMC10802480 DOI: 10.1101/2024.01.08.574738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Exchange protein directly activated by cAMP (EPAC1) mediates the intracellular functions of a critical stress-response second messenger, cAMP. Herein, we report that EPAC1 is a cellular substrate of protein SUMOylation, a prevalent stress-response posttranslational modification. Site-specific mapping of SUMOylation by mass spectrometer leads to identifying K561 as a primary SUMOylation site in EPAC1. Sequence and site-directed mutagenesis analyses reveal a functional SUMO-interacting motif required for cellular SUMOylation of EPAC1. SUMO modification of EPAC1 mediates its heat shock-induced Rap1/2 activation in a cAMP-independent manner. Structural modeling and molecular dynamics simulation studies demonstrate that SUMO substituent on K561 of EPAC1 promotes Rap1 interaction by increasing the buried surface area between the SUMOylated receptor and its effector. Our studies identify a functional SUMOylation site in EPAC1 and unveil a novel mechanism in which SUMOylation of EPAC1 leads to its autonomous activation. The findings of SUMOylation-mediated activation of EPAC1 not only provide new insights into our understanding of cellular regulation of EPAC1 but also will open up a new field of experimentation concerning the cross-talk between cAMP/EPAC1 signaling and protein SUMOylation, two major cellular stress response pathways, during cellular homeostasis.
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2
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Zaïmia N, Obeid J, Varrault A, Sabatier J, Broca C, Gilon P, Costes S, Bertrand G, Ravier MA. GLP-1 and GIP receptors signal through distinct β-arrestin 2-dependent pathways to regulate pancreatic β cell function. Cell Rep 2023; 42:113326. [PMID: 37897727 DOI: 10.1016/j.celrep.2023.113326] [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: 05/10/2023] [Revised: 09/14/2023] [Accepted: 10/07/2023] [Indexed: 10/30/2023] Open
Abstract
Glucagon-like peptide 1 (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIPR) receptors are G-protein-coupled receptors involved in glucose homeostasis. Diabetogenic conditions decrease β-arrestin 2 (ARRB2) levels in human islets. In mouse β cells, ARRB2 dampens insulin secretion by partially uncoupling cyclic AMP (cAMP)/protein kinase A (PKA) signaling at physiological doses of GLP-1, whereas at pharmacological doses, the activation of extracellular signal-related kinase (ERK)/cAMP-responsive element-binding protein (CREB) requires ARRB2. In contrast, GIP-potentiated insulin secretion needs ARRB2 in mouse and human islets. The GIPR-ARRB2 axis is not involved in cAMP/PKA or ERK signaling but does mediate GIP-induced F-actin depolymerization. Finally, the dual GLP-1/GIP agonist tirzepatide does not require ARRB2 for the potentiation of insulin secretion. Thus, ARRB2 plays distinct roles in regulating GLP-1R and GIPR signaling, and we highlight (1) its role in the physiological context and the possible functional consequences of its decreased expression in pathological situations such as diabetes and (2) the importance of assessing the signaling pathways engaged by the agonists (biased/dual) for therapeutic purposes.
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Affiliation(s)
- Nour Zaïmia
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Joelle Obeid
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Annie Varrault
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | | | | | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimental et Clinique, Pôle d'Endocrinologie, Diabète, et Nutrition, Brussels, Belgium
| | - Safia Costes
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
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3
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Slika H, Mansour H, Nasser SA, Shaito A, Kobeissy F, Orekhov AN, Pintus G, Eid AH. Epac as a tractable therapeutic target. Eur J Pharmacol 2023; 945:175645. [PMID: 36894048 DOI: 10.1016/j.ejphar.2023.175645] [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: 08/21/2022] [Revised: 02/26/2023] [Accepted: 03/06/2023] [Indexed: 03/09/2023]
Abstract
In 1957, cyclic adenosine monophosphate (cAMP) was identified as the first secondary messenger, and the first signaling cascade discovered was the cAMP-protein kinase A (PKA) pathway. Since then, cAMP has received increasing attention given its multitude of actions. Not long ago, a new cAMP effector named exchange protein directly activated by cAMP (Epac) emerged as a critical mediator of cAMP's actions. Epac mediates a plethora of pathophysiologic processes and contributes to the pathogenesis of several diseases such as cancer, cardiovascular disease, diabetes, lung fibrosis, neurological disorders, and others. These findings strongly underscore the potential of Epac as a tractable therapeutic target. In this context, Epac modulators seem to possess unique characteristics and advantages and hold the promise of providing more efficacious treatments for a wide array of diseases. This paper provides an in-depth dissection and analysis of Epac structure, distribution, subcellular compartmentalization, and signaling mechanisms. We elaborate on how these characteristics can be utilized to design specific, efficient, and safe Epac agonists and antagonists that can be incorporated into future pharmacotherapeutics. In addition, we provide a detailed portfolio for specific Epac modulators highlighting their discovery, advantages, potential concerns, and utilization in the context of clinical disease entities.
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Affiliation(s)
- Hasan Slika
- Department of Pharmacology and Toxicology, American University of Beirut, Beirut, P.O. Box 11-0236, Lebanon.
| | - Hadi Mansour
- Department of Pharmacology and Toxicology, American University of Beirut, Beirut, P.O. Box 11-0236, Lebanon.
| | | | - Abdullah Shaito
- Biomedical Research Center, Qatar University, Doha, P.O. Box: 2713, Qatar.
| | - Firas Kobeissy
- Department of Neurobiology and Neuroscience, Morehouse School of Medicine, Atlanta, Georgia, USA.
| | - Alexander N Orekhov
- Laboratory of Cellular and Molecular Pathology of Cardiovascular System, Institute of Human Morphology, 3 Tsyurupa Street, Moscow, 117418, Russia; Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, 8 Baltiiskaya Street, Moscow, 125315, Russia; Institute for Atherosclerosis Research, Skolkovo Innovative Center, Osennyaya Street 4-1-207, Moscow, 121609, Russia.
| | - Gianfranco Pintus
- Department of Biomedical Sciences, University of Sassari, 07100, Sassari, Italy.
| | - Ali H Eid
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, P.O. Box 2713, Qatar.
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4
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Chen H, Shen Y, Liang Y, Qiu Y, Xu M, Li C. Selexipag improves Lipopolysaccharide-induced ARDS on C57BL/6 mice by modulating the cAMP/PKA and cAMP/Epac1 signaling pathways. Biol Pharm Bull 2022; 45:1043-1052. [DOI: 10.1248/bpb.b21-01057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hongliu Chen
- Department of Emergency, the First Affiliated Hospital of Guangxi Medical University
| | - Ying Shen
- General Practice School, Guangxi Medical University
| | - Yi Liang
- Department of Respiratory Medicine, the First Affiliated Hospital of Guangxi Medical University
| | - Ying Qiu
- Department of Emergency, the First Affiliated Hospital of Guangxi Medical University
| | - Meili Xu
- Department of Emergency, the First Affiliated Hospital of Guangxi Medical University
| | - Chaoqian Li
- Department of Emergency, the First Affiliated Hospital of Guangxi Medical University
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5
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Ni Z, Cheng X. Origin and Isoform Specific Functions of Exchange Proteins Directly Activated by cAMP: A Phylogenetic Analysis. Cells 2021; 10:cells10102750. [PMID: 34685730 PMCID: PMC8534922 DOI: 10.3390/cells10102750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/09/2021] [Accepted: 10/09/2021] [Indexed: 12/21/2022] Open
Abstract
Exchange proteins directly activated by cAMP (EPAC1 and EPAC2) are one of the several families of cellular effectors of the prototypical second messenger cAMP. To understand the origin and molecular evolution of EPAC proteins, we performed a comprehensive phylogenetic analysis of EPAC1 and EPAC2. Our study demonstrates that unlike its cousin PKA, EPAC proteins are only present in multicellular Metazoa. Within the EPAC family, EPAC1 is only associated with chordates, while EPAC2 spans the entire animal kingdom. Despite a much more contemporary origin, EPAC1 proteins show much more sequence diversity among species, suggesting that EPAC1 has undergone more selection and evolved faster than EPAC2. Phylogenetic analyses of the individual cAMP binding domain (CBD) and guanine nucleotide exchange (GEF) domain of EPACs, two most conserved regions between the two isoforms, further reveal that EPAC1 and EPAC2 are closely clustered together within both the larger cyclic nucleotide receptor and RAPGEF families. These results support the notion that EPAC1 and EPAC2 share a common ancestor resulting from a fusion between the CBD of PKA and the GEF from RAPGEF1. On the other hand, the two terminal extremities and the RAS-association (RA) domains show the most sequence diversity between the two isoforms. Sequence diversities within these regions contribute significantly to the isoform-specific functions of EPACs. Importantly, unique isoform-specific sequence motifs within the RA domain have been identified.
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Affiliation(s)
- Zhuofu Ni
- Department of Integrative Biology & Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Xiaodong Cheng
- Department of Integrative Biology & Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
- Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-713-500-7487
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Identification and Characterization of an Affimer Affinity Reagent for the Detection of the cAMP Sensor, EPAC1. Cells 2021; 10:cells10092307. [PMID: 34571955 PMCID: PMC8465552 DOI: 10.3390/cells10092307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 01/15/2023] Open
Abstract
An exchange protein directly activated by cAMP 1 (EPAC1) is an intracellular sensor for cAMP that is involved in a wide variety of cellular and physiological processes in health and disease. However, reagents are lacking to study its association with intracellular cAMP nanodomains. Here, we use non-antibody Affimer protein scaffolds to develop isoform-selective protein binders of EPAC1. Phage-display screens were carried out against purified, biotinylated human recombinant EPAC1ΔDEP protein (amino acids 149–811), which identified five potential EPAC1-selective Affimer binders. Dot blots and indirect ELISA assays were next used to identify Affimer 780A as the top EPAC1 binder. Mutagenesis studies further revealed a potential interaction site for 780A within the EPAC1 cyclic nucleotide binding domain (CNBD). In addition, 780A was shown to co-precipitate EPAC1 from transfected cells and co-localize with both wild-type EPAC1 and a mis-targeting mutant of EPAC1(K212R), predominantly in perinuclear and cytosolic regions of cells, respectively. As a novel EPAC1-selective binder, 780A therefore has the potential to be used in future studies to further understand compartmentalization of the cAMP-EPAC1 signaling system.
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Abstract
The well-known second messenger cyclic adenosine monophosphate (cAMP) regulates the morphology and physiology of neurons and thus higher cognitive brain functions. The discovery of exchange protein activated by cAMP (Epac) as a guanine nucleotide exchange factor for Rap GTPases has shed light on protein kinase A (PKA)-independent functions of cAMP signaling in neural tissues. Studies of cAMP-Epac-mediated signaling in neurons under normal and disease conditions also revealed its diverse contributions to neurodevelopment, synaptic remodeling, and neurotransmitter release, as well as learning, memory, and emotion. In this mini-review, the various roles of Epac isoforms, including Epac1 and Epac2, highly expressed in neural tissues are summarized, and controversies or issues are highlighted that need to be resolved to uncover the critical functions of Epac in neural tissues and the potential for a new therapeutic target of mental disorders.
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Affiliation(s)
- Kyungmin Lee
- Laboratory for Behavioral Neural Circuitry and Physiology, Department of Anatomy, Brain Science & Engineering Institute, School of Medicine, Kyungpook National University, Daegu 41944, Korea
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8
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Guijarro-Belmar A, Domanski DM, Bo X, Shewan D, Huang W. The therapeutic potential of targeting exchange protein directly activated by cyclic adenosine 3',5'-monophosphate (Epac) for central nervous system trauma. Neural Regen Res 2021; 16:460-469. [PMID: 32985466 PMCID: PMC7996029 DOI: 10.4103/1673-5374.293256] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Millions of people worldwide are affected by traumatic spinal cord injury, which usually results in permanent sensorimotor disability. Damage to the spinal cord leads to a series of detrimental events including ischaemia, haemorrhage and neuroinflammation, which over time result in further neural tissue loss. Eventually, at chronic stages of traumatic spinal cord injury, the formation of a glial scar, cystic cavitation and the presence of numerous inhibitory molecules act as physical and chemical barriers to axonal regrowth. This is further hindered by a lack of intrinsic regrowth ability of adult neurons in the central nervous system. The intracellular signalling molecule, cyclic adenosine 3′,5′-monophosphate (cAMP), is known to play many important roles in the central nervous system, and elevating its levels as shown to improve axonal regeneration outcomes following traumatic spinal cord injury in animal models. However, therapies directly targeting cAMP have not found their way into the clinic, as cAMP is ubiquitously present in all cell types and its manipulation may have additional deleterious effects. A downstream effector of cAMP, exchange protein directly activated by cAMP 2 (Epac2), is mainly expressed in the adult central nervous system, and its activation has been shown to mediate the positive effects of cAMP on axonal guidance and regeneration. Recently, using ex vivo modelling of traumatic spinal cord injury, Epac2 activation was found to profoundly modulate the post-lesion environment, such as decreasing the activation of astrocytes and microglia. Pilot data with Epac2 activation also suggested functional improvement assessed by in vivo models of traumatic spinal cord injury. Therefore, targeting Epac2 in traumatic spinal cord injury could represent a novel strategy in traumatic spinal cord injury repair, and future work is needed to fully establish its therapeutic potential.
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Affiliation(s)
- Alba Guijarro-Belmar
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen; Sainsbury Wellcome Centre, University College London, London, UK
| | - Dominik Mateusz Domanski
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, UK
| | - Xuenong Bo
- Center for Neuroscience, Surgery and Trauma, Queen Mary University of London, London, UK
| | - Derryck Shewan
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, UK
| | - Wenlong Huang
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, UK
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9
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Keyes J, Ganesan A, Molinar-Inglis O, Hamidzadeh A, Zhang J, Ling M, Trejo J, Levchenko A, Zhang J. Signaling diversity enabled by Rap1-regulated plasma membrane ERK with distinct temporal dynamics. eLife 2020; 9:57410. [PMID: 32452765 PMCID: PMC7289600 DOI: 10.7554/elife.57410] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/22/2020] [Indexed: 12/23/2022] Open
Abstract
A variety of different signals induce specific responses through a common, extracellular-signal regulated kinase (ERK)-dependent cascade. It has been suggested that signaling specificity can be achieved through precise temporal regulation of ERK activity. Given the wide distrubtion of ERK susbtrates across different subcellular compartments, it is important to understand how ERK activity is temporally regulated at specific subcellular locations. To address this question, we have expanded the toolbox of Förster Resonance Energy Transfer (FRET)-based ERK biosensors by creating a series of improved biosensors targeted to various subcellular regions via sequence specific motifs to measure spatiotemporal changes in ERK activity. Using these sensors, we showed that EGF induces sustained ERK activity near the plasma membrane in sharp contrast to the transient activity observed in the cytoplasm and nucleus. Furthermore, EGF-induced plasma membrane ERK activity involves Rap1, a noncanonical activator, and controls cell morphology and EGF-induced membrane protrusion dynamics. Our work strongly supports that spatial and temporal regulation of ERK activity is integrated to control signaling specificity from a single extracellular signal to multiple cellular processes.
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Affiliation(s)
- Jeremiah Keyes
- Department of Pharmacology, University of California San Diego, La Jolla, United States
| | - Ambhighainath Ganesan
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Olivia Molinar-Inglis
- Department of Pharmacology, University of California San Diego, La Jolla, United States
| | - Archer Hamidzadeh
- Department of Biomedical Engineering and Yale Systems Biology Institute, Yale University, New Haven, United States
| | - Jinfan Zhang
- Department of Pharmacology, University of California San Diego, La Jolla, United States
| | - Megan Ling
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, United States
| | - JoAnn Trejo
- Department of Pharmacology, University of California San Diego, La Jolla, United States
| | - Andre Levchenko
- Department of Biomedical Engineering and Yale Systems Biology Institute, Yale University, New Haven, United States
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego, La Jolla, United States.,Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, United States.,Department of Bioengineering, University of California San Diego, La Jolla, United States
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10
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EPAC1 and EPAC2 promote nociceptor hyperactivity associated with chronic pain after spinal cord injury. NEUROBIOLOGY OF PAIN 2019; 7:100040. [PMID: 31890991 PMCID: PMC6926371 DOI: 10.1016/j.ynpai.2019.100040] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/15/2019] [Accepted: 11/20/2019] [Indexed: 12/19/2022]
Abstract
Chronic pain following spinal cord injury (SCI) is associated with electrical hyperactivity (spontaneous and evoked) in primary nociceptors. Cyclic adenosine monophosphate (cAMP) signaling is an important contributor to nociceptor excitability, and knockdown of the cAMP effector, exchange protein activated by cAMP (EPAC), has been shown to relieve pain-like responses in several chronic pain models. To examine potentially distinct roles of each EPAC isoform (EPAC1 and 2) in maintaining chronic pain, we used rat and mouse models of contusive spinal cord injury (SCI). Pharmacological inhibition of EPAC1 or 2 in a rat SCI model was sufficient to reverse SCI-induced nociceptor hyperactivity, indicating that EPAC1 and 2 signaling activity are complementary, with both required to maintain hyperactivity. However, EPAC activation was not sufficient to induce similar hyperactivity in nociceptors from naïve rats, and we observed no change in EPAC protein expression after SCI. In the mouse SCI model, inhibition of both EPAC isoforms through a combination of pharmacological inhibition and genetic deletion was required to reverse SCI-induced nociceptor hyperactivity. This was consistent with our finding that neither EPAC1-/- nor EPAC2-/- mice were protected against SCI-induced chronic pain as assessed with an operant mechanical conflict test. Thus, EPAC1 and 2 activity may play a redundant role in mouse nociceptors, although no corresponding change in EPAC protein expression levels was detected after SCI. Despite some differences between these species, our data demonstrate a fundamental role for both EPAC1 and EPAC2 in mechanisms maintaining nociceptor hyperactivity and chronic pain after SCI.
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11
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Llavero F, Arrazola Sastre A, Luque Montoro M, Martín MA, Arenas J, Lucia A, Zugaza JL. Small GTPases of the Ras superfamily and glycogen phosphorylase regulation in T cells. Small GTPases 2019; 12:106-113. [PMID: 31512989 DOI: 10.1080/21541248.2019.1665968] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Small GTPases, together with their regulatory and effector molecules, are key intermediaries in the complex signalling pathways that control almost all cellular processes, working as molecular switches to transduce extracellular cues into cellular responses that drive vital functions, such as intracellular transport, biomolecule synthesis, gene activation and cell survival. How all of these networks are linked to metabolic pathways is a subject of intensive study. Because any response to cellular action requires some form of energy input, elucidating how cells coordinate the signals that lead to a tangible response involving metabolism is central to understand cellular activities. In this review, we summarize recent advances in our understanding of the molecular basis of the crosstalk between small GTPases of the Ras superfamily, specifically Rac1 and Ras/Rap1, and glycogen phosphorylase in T lymphocytes. Abbreviations: ADCY: adenylyl cyclase; ADCY6: adenylyl cyclase 6; BCR: B cell receptor; cAMP: 3',5'-cyclic adenosine monophosphate; CRIB: Cdc42/Rac binding domain; DLPFC: dysfunction of the dorsolateral prefrontal cortex; EGFR: epidermal growth factor receptor; Epac2: exchange protein directly activated by cAMP; GDP: guanodine-5'-diphosphate; GPCRs: G protein-coupled receptors; GTP: guanodin-5'-triphosphate; IL2: interleukin 2; IL2-R: interleukin 2 receptor; JAK: janus kinases; MAPK: mitogen-activated protein kinase; O-GlcNAc: O-glycosylation; PAK1: p21 activated kinase 1; PI3K: phosphatidylinositol 3-kinase; PK: phosphorylase kinase; PKA: cAMP-dependent protein kinase A; PKCθ: protein kinase Cθ; PLCγ: phospholipase Cγ; Src: proto-oncogene tyrosine-protein kinase c; STAT: signal transducer and activator of transcription proteins.
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Affiliation(s)
- Francisco Llavero
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU , Leioa, Spain.,Faculty of Sport Sciences, Universidad Europea de Madrid , Madrid, Spain
| | - Alazne Arrazola Sastre
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU , Leioa, Spain.,Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, UPV/EHU , Leioa, Spain
| | - Miriam Luque Montoro
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU , Leioa, Spain
| | - Miguel A Martín
- Enfermedades Raras, Mitocondriales y Neuromusculares., Instituto de Investigación Hospital 12 de Octubre (i+12) , Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III , Madrid, Spain
| | - Joaquín Arenas
- Enfermedades Raras, Mitocondriales y Neuromusculares., Instituto de Investigación Hospital 12 de Octubre (i+12) , Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III , Madrid, Spain
| | - Alejandro Lucia
- Faculty of Sport Sciences, Universidad Europea de Madrid , Madrid, Spain.,Enfermedades Raras, Mitocondriales y Neuromusculares., Instituto de Investigación Hospital 12 de Octubre (i+12) , Madrid, Spain.,Center for Biomedical Network Research on Frailty and Healthy Aging (CIBER FES), Instituto de Salud Carlos III , Madrid, Spain
| | - José L Zugaza
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU , Leioa, Spain.,Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, UPV/EHU , Leioa, Spain.,IKERBASQUE, Basque Foundation for Science , Bilbao, Spain
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12
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Tang H, Wang L, Chen Y, He J, Qu L, Guo Y, Liu Y, Liu X, Lin H. Ovulation is associated with the LH-dependent induction of pla2g4aa in zebrafish. Mol Cell Endocrinol 2018; 473:53-60. [PMID: 29326060 DOI: 10.1016/j.mce.2018.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/17/2017] [Accepted: 01/07/2018] [Indexed: 01/14/2023]
Abstract
The effects of the preovulatory luteinizing hormone (LH) surge on the ovulatory process are mediated by prostaglandins (PGs), the synthesis of which involves prostaglandin synthetase and cytosolic phospholipase A2 (cPLA2). In our previous study, we systematically investigated the function of prostaglandin endoperoxide synthase (ptgs) genes on ovulation in zebrafish. However, the role of cPLA2 in ovulation was not determined in zebrafish. In this study, we investigated the function of cpla2α in PGs production and ovulation in periovulatory follicles. Our data showed that the expression of pla2g4aa increased during zebrafish folliculogenesis and the follicular layer was the primary region with expression of pla2g4aa. In addition, the expression of pla2g4aa was regulated by LH in vitro and in vivo. Furthermore, injection of AACOCF3, a specific inhibitor of cPLA2, significantly reduced ovarian PGs level and blocked hCG-induced ovulation. Collectively, these findings suggest that pla2g4aa is related to the ovulation process in zebrafish.
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Affiliation(s)
- Haipei Tang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Le Wang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yu Chen
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Jianan He
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Ling Qu
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yin Guo
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yun Liu
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Xiaochun Liu
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Haoran Lin
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
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13
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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: 135] [Impact Index Per Article: 22.5] [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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14
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Insights into exchange factor directly activated by cAMP (EPAC) as potential target for cancer treatment. Mol Cell Biochem 2018; 447:77-92. [PMID: 29417338 DOI: 10.1007/s11010-018-3294-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 01/19/2018] [Indexed: 01/02/2023]
Abstract
Cancer remains a global health problem and approximately 1.7 million new cancer cases are diagnosed every year worldwide. Although diverse molecules are currently being explored as targets for cancer therapy the tumor treatment and therapy is highly tricky. Secondary messengers are important for hormone-mediated signaling pathway. Cyclic AMP (cAMP), a secondary messenger responsible for various physiological processes regulates cell metabolism by activating Protein kinase A (PKA) and by targeting exchange protein directly activated by cAMP (EPAC). EPAC is present in two isoforms EPAC1 and EPAC2, which exhibit different tissue distribution and is involved in GDP/GTP exchange along with activating Rap1- and Rap2-mediated signaling pathways. EPAC is also known for its dual role in cancer as pro- and anti-proliferative in addition to metastasis. Results after perturbing EPAC activity suggests its involvement in cancer cell migration, proliferation, and cytoskeleton remodeling which makes it a potential therapeutic target for cancer treatments.
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15
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Barker G, Parnell E, van Basten B, Buist H, Adams DR, Yarwood SJ. The Potential of a Novel Class of EPAC-Selective Agonists to Combat Cardiovascular Inflammation. J Cardiovasc Dev Dis 2017; 4:jcdd4040022. [PMID: 29367551 PMCID: PMC5753123 DOI: 10.3390/jcdd4040022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 11/23/2017] [Accepted: 11/30/2017] [Indexed: 02/07/2023] Open
Abstract
The cyclic 3′,5′-adenosine monophosphate (cAMP) sensor enzyme, EPAC1, is a candidate drug target in vascular endothelial cells (VECs) due to its ability to attenuate proinflammatory cytokine signalling normally associated with cardiovascular diseases (CVDs), including atherosclerosis. This is through the EPAC1-dependent induction of the suppressor of cytokine signalling gene, SOCS3, which targets inflammatory signalling proteins for ubiquitinylation and destruction by the proteosome. Given this important role for the EPAC1/SOCS3 signalling axis, we have used high throughput screening (HTS) to identify small molecule EPAC1 regulators and have recently isolated the first known non-cyclic nucleotide (NCN) EPAC1 agonist, I942. I942 therefore represents the first in class, isoform selective EPAC1 activator, with the potential to suppress pro-inflammatory cytokine signalling with a reduced risk of side effects associated with general cAMP-elevating agents that activate multiple response pathways. The development of augmented I942 analogues may therefore provide improved research tools to validate EPAC1 as a potential therapeutic target for the treatment of chronic inflammation associated with deadly CVDs.
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Affiliation(s)
- Graeme Barker
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | - Euan Parnell
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Boy van Basten
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | - Hanna Buist
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | - David R Adams
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | - Stephen J Yarwood
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK.
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16
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Rehmann H. Interaction of Epac with Non-canonical Cyclic Nucleotides. Handb Exp Pharmacol 2017; 238:135-147. [PMID: 27900608 DOI: 10.1007/164_2015_37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Epac1 and Epac2 are cyclic nucleotide-binding (CNB) domain containing proteins, which were originally identified as cAMP-regulated guanine nucleotide exchange factors (GEFs) for the small G-protein Rap. Therefore, Epac proteins founded next to protein kinase A (PKA) and cyclic nucleotide-regulated ion channels the third group of cAMP-responsive proteins in higher organisms. Epac proteins are involved in the regulation of several physiological processes. In particular Epac1 mediates the regulation of molecular processes underlying cell adhesion and mobility. In the pancreas activation of Epac2 potentiates the release of glucose-induced insulin secretion and received attention as a putative target for antidiabetic treatment. While the regulation of Epac by cAMP has been analysed in structural and biochemical detail, less is known on the interaction of Epac with non-canonical cyclic nucleotides. This chapter will discuss to what extent other cyclic purines than cAMP or cyclic pyrimidine could act as Epac agonists or antagonists. The focus will be on the biophysical analysis of the interaction between Epac and these cyclic nucleotides.
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Affiliation(s)
- Holger Rehmann
- Molecular Cancer Research and Cancer Genomics Netherlands, Center for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands.
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17
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Alenkvist I, Gandasi NR, Barg S, Tengholm A. Recruitment of Epac2A to Insulin Granule Docking Sites Regulates Priming for Exocytosis. Diabetes 2017; 66:2610-2622. [PMID: 28679628 DOI: 10.2337/db17-0050] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 06/20/2017] [Indexed: 11/13/2022]
Abstract
Epac is a cAMP-activated guanine nucleotide exchange factor that mediates cAMP signaling in various types of cells, including β-cells, where it is involved in the control of insulin secretion. Upon activation, the protein redistributes to the plasma membrane, but the underlying molecular mechanisms and functional consequences are unclear. Using quantitative high-resolution microscopy, we found that cAMP elevation caused rapid binding of Epac2A to the β-cell plasma membrane, where it accumulated specifically at secretory granules and rendered them more prone to undergo exocytosis. cAMP-dependent membrane binding required the high-affinity cyclic nucleotide-binding (CNB) and Ras association domains, but not the disheveled-Egl-10-pleckstrin domain. Although the N-terminal low-affinity CNB domain (CNB-A) was dispensable for the translocation to the membrane, it was critical for directing Epac2A to the granule sites. Epac1, which lacks the CNB-A domain, was recruited to the plasma membrane but did not accumulate at granules. We conclude that Epac2A controls secretory granule release by binding to the exocytosis machinery, an effect that is enhanced by prior cAMP-dependent accumulation of the protein at the plasma membrane.
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Affiliation(s)
- Ida Alenkvist
- Department of Medical Cell Biology, Uppsala University Biomedical Centre, Uppsala, Sweden
| | - Nikhil R Gandasi
- Department of Medical Cell Biology, Uppsala University Biomedical Centre, Uppsala, Sweden
| | - Sebastian Barg
- Department of Medical Cell Biology, Uppsala University Biomedical Centre, Uppsala, Sweden
| | - Anders Tengholm
- Department of Medical Cell Biology, Uppsala University Biomedical Centre, Uppsala, Sweden
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18
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Shah B, Püschel AW. Regulation of Rap GTPases in mammalian neurons. Biol Chem 2017; 397:1055-69. [PMID: 27186679 DOI: 10.1515/hsz-2016-0165] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/06/2016] [Indexed: 12/15/2022]
Abstract
Small GTPases are central regulators of many cellular processes. The highly conserved Rap GTPases perform essential functions in the mammalian nervous system during development and in mature neurons. During neocortical development, Rap1 is required to regulate cadherin- and integrin-mediated adhesion. In the adult nervous system Rap1 and Rap2 regulate the maturation and plasticity of dendritic spine and synapses. Although genetic studies have revealed important roles of Rap GTPases in neurons, their regulation by guanine nucleotide exchange factors (GEFs) that activate them and GTPase activating proteins (GAPs) that inactivate them by stimulating their intrinsic GTPase activity is just beginning to be explored in vivo. Here we review how GEFs and GAPs regulate Rap GTPases in the nervous system with a focus on their in vivo function.
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19
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Park JY, Juhnn YS. cAMP signaling increases histone deacetylase 8 expression via the Epac2-Rap1A-Akt pathway in H1299 lung cancer cells. Exp Mol Med 2017; 49:e297. [PMID: 28232663 PMCID: PMC5336561 DOI: 10.1038/emm.2016.152] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 12/16/2022] Open
Abstract
This study was performed to investigate the signaling pathway that mediates cyclic AMP (cAMP)-induced inhibition of histone deacetylase 8 (HDAC8) degradation, and the effect and underlying mechanisms of the resulting increase in HDAC8 expression on cisplatin-induced apoptosis in lung cancer cells. cAMP signaling increased HDAC8 expression via a protein kinase A (PKA)-independent pathway in H1299 non-small cell lung cancer cells. However, treatment with a selective activator of an exchange protein that was activated by cAMP (Epac) increased HDAC8 expression, and Epac2 inhibition abolished the isoproterenol (ISO)-induced increase in HDAC8 expression. ISO and the Epac activator activated Rap1, and Rap1A activation increased HDAC8 expression; moreover, inhibition of Rap1A with a dominant negative Rap1A or by shRNA-mediated knockdown abolished the ISO-induced increase in HDAC8 expression. Activation of cAMP signaling and Rap1A decreased the activating phosphorylation of Akt. Akt inhibition with a pharmacological inhibitor or expression of a dominant negative Akt inhibited the MKK4/JNK pathway and increased HDAC8 expression. The Akt inhibitor-induced increase in HDAC8 expression was abolished by pretreatment with proteasomal or lysosomal inhibitors. The ISO treatment increased cisplatin-induced apoptosis, which was abolished by HDAC8 knockdown. Exogenous HDAC8 expression increased cisplatin-induced apoptosis and decreased TIPRL expression, and the knockdown of TIPRL increased the apoptosis of cisplatin-treated cells. The ISO treatment decreased cisplatin-induced transcription of the TIPRL gene in a HDAC8-dependent manner. In conclusion, the Epac–Rap1–Akt pathway mediates cAMP signaling-induced inhibition of JNK-dependent HDAC8 degradation, and the resulting HDAC8 increase augments cisplatin-induced apoptosis by repressing TIPRL expression in H1299 lung cancer cells.
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Affiliation(s)
- Ji-Yeon Park
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea.,Department of Biomedical Sciences and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Yong-Sung Juhnn
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea.,Department of Biomedical Sciences and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
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20
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Fujita T, Umemura M, Yokoyama U, Okumura S, Ishikawa Y. The role of Epac in the heart. Cell Mol Life Sci 2017; 74:591-606. [PMID: 27549789 PMCID: PMC11107744 DOI: 10.1007/s00018-016-2336-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/21/2016] [Accepted: 08/09/2016] [Indexed: 02/08/2023]
Abstract
As one of the most important second messengers, 3',5'-cyclic adenosine monophosphate (cAMP) mediates various extracellular signals including hormones and neurotransmitters, and induces appropriate responses in diverse types of cells. Since cAMP was formerly believed to transmit signals through only two direct target molecules, protein kinase A and the cyclic nucleotide-gated channel, the sensational discovery in 1998 of another novel direct effecter of cAMP [exchange proteins directly activated by cAMP (Epac)] attracted a great deal of scientific interest in cAMP signaling. Numerous studies on Epac have since disclosed its important functions in various tissues in the body. Recently, observations of genetically manipulated mice in various pathogenic models have begun to reveal the in vivo significance of previous in vitro or cellular-level findings. Here, we focused on the function of Epac in the heart. Accumulating evidence has revealed that both Epac1 and Epac2 play important roles in the structure and function of the heart under physiological and pathological conditions. Accordingly, developing the ability to regulate cAMP-mediated signaling through Epac may lead to remarkable new therapies for the treatment of cardiac diseases.
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Affiliation(s)
- Takayuki Fujita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Masanari Umemura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Utako Yokoyama
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoshi Okumura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
- Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Yoshihiro Ishikawa
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
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21
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Lezoualc'h F, Fazal L, Laudette M, Conte C. Cyclic AMP Sensor EPAC Proteins and Their Role in Cardiovascular Function and Disease. Circ Res 2016; 118:881-97. [PMID: 26941424 DOI: 10.1161/circresaha.115.306529] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
cAMP is a universal second messenger that plays central roles in cardiovascular regulation influencing gene expression, cell morphology, and function. A crucial step toward a better understanding of cAMP signaling came 18 years ago with the discovery of the exchange protein directly activated by cAMP (EPAC). The 2 EPAC isoforms, EPAC1 and EPAC2, are guanine-nucleotide exchange factors for the Ras-like GTPases, Rap1 and Rap2, which they activate independently of the classical effector of cAMP, protein kinase A. With the development of EPAC pharmacological modulators, many reports in the literature have demonstrated the critical role of EPAC in the regulation of various cAMP-dependent cardiovascular functions, such as calcium handling and vascular tone. EPAC proteins are coupled to a multitude of effectors into distinct subcellular compartments because of their multidomain architecture. These novel cAMP sensors are not only at the crossroads of different physiological processes but also may represent attractive therapeutic targets for the treatment of several cardiovascular disorders, including cardiac arrhythmia and heart failure.
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Affiliation(s)
- Frank Lezoualc'h
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.).
| | - Loubina Fazal
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.)
| | - Marion Laudette
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.)
| | - Caroline Conte
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.)
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22
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Lewis AE, Aesoy R, Bakke M. Role of EPAC in cAMP-Mediated Actions in Adrenocortical Cells. Front Endocrinol (Lausanne) 2016; 7:63. [PMID: 27379015 PMCID: PMC4904129 DOI: 10.3389/fendo.2016.00063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022] Open
Abstract
Adrenocorticotropic hormone regulates adrenal steroidogenesis mainly via the intracellular signaling molecule cAMP. The effects of cAMP are principally relayed by activating protein kinase A (PKA) and the more recently discovered exchange proteins directly activated by cAMP 1 and 2 (EPAC1 and EPAC2). While the intracellular roles of PKA have been extensively studied in steroidogenic tissues, those of EPACs are only emerging. EPAC1 and EPAC2 are encoded by the genes RAPGEF3 and RAPGEF4, respectively. Whereas EPAC1 is ubiquitously expressed, the expression of EPAC2 is more restricted, and typically found in endocrine tissues. Alternative promoter usage of RAPGEF4 gives rise to three different isoforms of EPAC2 that vary in their N-termini (EPAC2A, EPAC2B, and EPAC2C) and that exhibit distinct expression patterns. EPAC2A is expressed in the brain and pancreas, EPAC2B in steroidogenic cells of the adrenal gland and testis, and EPAC2C has until now only been found in the liver. In this review, we discuss current knowledge on EPAC expression and function with focus on the known roles of EPAC in adrenal gland physiology.
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Affiliation(s)
- Aurélia E. Lewis
- Department of Molecular Biology, University of Bergen, Bergen, Norway
- *Correspondence: Aurélia E. Lewis,
| | - Reidun Aesoy
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
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23
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Shariati B, Thompson EL, Nicol GD, Vasko MR. Epac activation sensitizes rat sensory neurons through activation of Ras. Mol Cell Neurosci 2015; 70:54-67. [PMID: 26596174 DOI: 10.1016/j.mcn.2015.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 11/04/2015] [Accepted: 11/16/2015] [Indexed: 10/24/2022] Open
Abstract
Guanine nucleotide exchange factors directly activated by cAMP (Epacs) have emerged as important signaling molecules mediating persistent hypersensitivity in animal models of inflammation, by augmenting the excitability of sensory neurons. Although Epacs activate numerous downstream signaling cascades, the intracellular signaling which mediates Epac-induced sensitization of capsaicin-sensitive sensory neurons remains unknown. Here, we demonstrate that selective activation of Epacs with 8-CPT-2'-O-Me-cAMP-AM (8CPT-AM) increases the number of action potentials (APs) generated by a ramp of depolarizing current and augments the evoked release of calcitonin gene-related peptide (CGRP) from isolated rat sensory neurons. Internal perfusion of capsaicin-sensitive sensory neurons with GDP-βS, substituted for GTP, blocks the ability of 8CPT-AM to increase AP firing, demonstrating that Epac-induced sensitization is G-protein dependent. Treatment with 8CPT-AM activates the small G-proteins Rap1 and Ras in cultures of sensory neurons. Inhibition of Rap1, by internal perfusion of a Rap1-neutralizing antibody or through a reduction in the expression of the protein using shRNA does not alter the Epac-induced enhancement of AP generation or CGRP release, despite the fact that in most other cell types, Epacs act as Rap-GEFs. In contrast, inhibition of Ras through expression of a dominant negative Ras (DN-Ras) or through internal perfusion of a Ras-neutralizing antibody blocks the increase in AP firing and attenuates the increase in the evoked release of CGRP induced by Epac activation. Thus, in this subpopulation of nociceptive sensory neurons, it is the novel interplay between Epacs and Ras, rather than the canonical Epacs and Rap1 pathway, that is critical for mediating Epac-induced sensitization.
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Affiliation(s)
- Behzad Shariati
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Eric L Thompson
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Grant D Nicol
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Michael R Vasko
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Exchange Protein Directly Activated by cAMP (EPAC) Regulates Neuronal Polarization through Rap1B. J Neurosci 2015; 35:11315-29. [PMID: 26269639 DOI: 10.1523/jneurosci.3645-14.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Acquisition of neuronal polarity is a complex process involving cellular and molecular events. The second messenger cAMP is involved in axonal specification through activation of protein kinase A. However, an alternative cAMP-dependent mechanism involves the exchange protein directly activated by cAMP (EPAC), which also responds to physiological changes in cAMP concentration, promoting activation of the small Rap GTPases. Here, we present evidence that EPAC signaling contributes to axon specification and elongation. In primary rat hippocampal neurons, EPAC isoforms were expressed differentially during axon specification. Furthermore, 8-pCPT, an EPAC pharmacological activator, and genetic manipulations of EPAC in neurons induced supernumerary axons indicative of Rap1b activation. Moreover, 8-pCPT-treated neurons expressed ankyrin G and other markers of mature axons such as synaptophysin and axonal accumulation of vGLUT1. In contrast, pharmacological inhibition of EPAC delayed neuronal polarity. Genetic manipulations to inactivate EPAC1 using either shRNA or neurons derived from EPAC1 knock-out (KO) mice led to axon elongation and polarization defects. Interestingly, multiaxonic neurons generated by 8-pCPT treatments in wild-type neurons were not found in EPAC1 KO mice neurons. Altogether, these results propose that EPAC signaling is an alternative and complementary mechanism for cAMP-dependent axon determination. SIGNIFICANCE STATEMENT This study identifies the guanine exchange factor responsible for Rap1b activation during neuronal polarization and provides an alternate explanation for cAMP-dependent acquisition of neuronal polarity.
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Sugawara K, Shibasaki T, Takahashi H, Seino S. Structure and functional roles of Epac2 (Rapgef4). Gene 2015; 575:577-83. [PMID: 26390815 DOI: 10.1016/j.gene.2015.09.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/13/2015] [Accepted: 09/15/2015] [Indexed: 10/24/2022]
Abstract
Epac (exchange protein activated by cyclic-AMP) 2 is a direct target of 3'-5'-cyclic adenosine monophosphate (cAMP) and is involved in cAMP-mediated signal transduction through activation of the Ras-like small GTPase Rap. Crystallographic analyses revealed that activation of Epac2 by cAMP is accompanied by dynamic structural changes. Epac2 is expressed mainly in brain, neuroendocrine and endocrine tissues, and is involved in diverse cellular functions in the tissues. In this review, we summarize the structure and function of Epac2. We also discuss the physiological and pathophysiological roles of Epac2, and the possibility of Epac2 as a therapeutic target.
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Affiliation(s)
- Kenji Sugawara
- Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan; Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tadao Shibasaki
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Harumi Takahashi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Susumu Seino
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
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26
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Parnell E, Smith BO, Yarwood SJ. The cAMP sensors, EPAC1 and EPAC2, display distinct subcellular distributions despite sharing a common nuclear pore localisation signal. Cell Signal 2015; 27:989-96. [PMID: 25683912 PMCID: PMC4372255 DOI: 10.1016/j.cellsig.2015.02.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/08/2015] [Indexed: 11/22/2022]
Abstract
We have identified a conserved nuclear pore localisation signal (NPLS; amino acids 764-838 of EPAC1) in the catalytic domains of the cAMP-sensors, EPAC1 and EPAC2A. Consequently, EPAC1 is mainly localised to the nuclear pore complex in HEK293T cells where it becomes activated following stimulation with cAMP. In contrast, structural models indicate that the cAMP-binding domain of EPAC2A (CNBD1) blocks access to the conserved NPLS in EPAC2A, reducing its ability to interact with nuclear binding sites. Consequently, a naturally occurring EPAC2 isoform, EPAC2B, which lacks CNBD1 is enriched in nuclear fractions, similar to EPAC1. Structural differences in EPAC isoforms may therefore determine their intracellular location and their response to elevations in intracellular cAMP.
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Affiliation(s)
- Euan Parnell
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK
| | - Brian O Smith
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK
| | - Stephen J Yarwood
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ, UK.
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27
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Parnell E, Palmer TM, Yarwood SJ. The future of EPAC-targeted therapies: agonism versus antagonism. Trends Pharmacol Sci 2015; 36:203-14. [PMID: 25744542 PMCID: PMC4392396 DOI: 10.1016/j.tips.2015.02.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/03/2015] [Accepted: 02/05/2015] [Indexed: 02/06/2023]
Abstract
Although tractable to drug development, targeting of cAMP signalling has side effects. Selectively targeting EPAC1 and EPAC2 cAMP sensor enzymes may limit some of these off-target effects. EPAC agonists could be used to treat vascular inflammation (EPAC1) or type 2 diabetes (EPAC2). EPAC1 and EPAC2 antagonists could be used to treat heart disease.
Pharmaceutical manipulation of cAMP levels exerts beneficial effects through the regulation of the exchange protein activated by cAMP (EPAC) and protein kinase A (PKA) signalling routes. Recent attention has turned to the specific regulation of EPAC isoforms (EPAC1 and EPAC2) as a more targeted approach to cAMP-based therapies. For example, EPAC2-selective agonists could promote insulin secretion from pancreatic β cells, whereas EPAC1-selective agonists may be useful in the treatment of vascular inflammation. By contrast, EPAC1 and EPAC2 antagonists could both be useful in the treatment of heart failure. Here we discuss whether the best way forward is to design EPAC-selective agonists or antagonists and the current strategies being used to develop isoform-selective, small-molecule regulators of EPAC1 and EPAC2 activity.
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Affiliation(s)
- Euan Parnell
- Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Timothy M Palmer
- School of Pharmacy, University of Bradford, Bradford BD7 1DP, UK
| | - Stephen J Yarwood
- Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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28
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Desman G, Waintraub C, Zippin JH. Investigation of cAMP microdomains as a path to novel cancer diagnostics. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2636-45. [PMID: 25205620 DOI: 10.1016/j.bbadis.2014.08.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/21/2014] [Accepted: 08/26/2014] [Indexed: 12/17/2022]
Abstract
Understanding of cAMP signaling has greatly improved over the past decade. The advent of live cell imaging techniques and more specific pharmacologic modulators has led to an improved understanding of the intricacies by which cAMP is able to modulate such a wide variety of cellular pathways. It is now appreciated that cAMP is able to activate multiple effector proteins at distinct areas in the cell leading to the activation of very different downstream targets. The investigation of signaling proteins in cancer is a common route to the development of diagnostic tools, prognostic tools, and/or therapeutic targets, and in this review we highlight how investigation of cAMP signaling microdomains driven by the soluble adenylyl cyclase in different cancers has led to the development of a novel cancer biomarker. Antibodies directed against the soluble adenylyl cyclase (sAC) are highly specific markers for melanoma especially for lentigo maligna melanoma and are being described as "second generation" cancer diagnostics, which are diagnostics that determine the 'state' of a cell and not just identify the cell type. Due to the wide presence of cAMP signaling pathways in cancer, we predict that further investigation of both sAC and other cAMP microdomains will lead to additional cancer biomarkers. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- Garrett Desman
- Department of Pathology, Joan and Sanford I. Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
| | - Caren Waintraub
- Albert Einstein College of Medicine at Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Department of Dermatology, Joan and Sanford I. Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
| | - Jonathan H Zippin
- Department of Dermatology, Joan and Sanford I. Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
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Role of soluble adenylyl cyclase in cell death and growth. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2646-55. [PMID: 25010002 DOI: 10.1016/j.bbadis.2014.06.034] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/26/2014] [Accepted: 06/27/2014] [Indexed: 12/13/2022]
Abstract
cAMP signaling is an evolutionarily conserved intracellular communication system controlling numerous cellular functions. Until recently, transmembrane adenylyl cyclase (tmAC) was considered the major source for cAMP in the cell, and the role of cAMP signaling was therefore attributed exclusively to the activity of this family of enzymes. However, increasing evidence demonstrates the role of an alternative, intracellular source of cAMP produced by type 10 soluble adenylyl cyclase (sAC). In contrast to tmAC, sAC produces cAMP in various intracellular microdomains close to specific cAMP targets, e.g., in nucleus and mitochondria. Ongoing research demonstrates involvement of sAC in diverse physiological and pathological processes. The present review is focused on the role of cAMP signaling, particularly that of sAC, in cell death and growth. Although the contributions of sAC to the regulation of these cellular functions have only recently been discovered, current data suggest that sAC plays key roles in mitochondrial bioenergetics and the mitochondrial apoptosis pathway, as well as cell proliferation and development. Furthermore, recent reports suggest the importance of sAC in several pathologies associated with apoptosis as well as in oncogenesis. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Abstract
The Dishevelled, EGL-10 and pleckstrin (DEP) domain is a globular protein domain that is present in about ten human protein families with well-defined structural features. A picture is emerging that DEP domains mainly function in the spatial and temporal control of diverse signal transduction events by recruiting proteins to the plasma membrane. DEP domains can interact with various partners at the membrane, including phospholipids and membrane receptors, and their binding is subject to regulation.
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Hoivik EA, Witsoe SL, Bergheim IR, Xu Y, Jakobsson I, Tengholm A, Doskeland SO, Bakke M. DNA methylation of alternative promoters directs tissue specific expression of Epac2 isoforms. PLoS One 2013; 8:e67925. [PMID: 23861833 PMCID: PMC3701594 DOI: 10.1371/journal.pone.0067925] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 05/23/2013] [Indexed: 12/22/2022] Open
Abstract
Epac 1 and Epac 2 (Epac1/2; exchange factors directly activated by cAMP) are multidomain proteins that mediate cellular responses upon activation by the signaling molecule cAMP. Epac1 is ubiquitously expressed, whereas Epac2 exhibits a restricted expression pattern. The gene encoding Epac2 gives rise to at least three protein isoforms (Epac2A, Epac2B and Epac2C) that exhibit confined tissue and cell specific expression profiles. Here, we describe alternative promoter usage for the different isoforms of Epac2, and demonstrate that the activity of these promoters depend on the DNA methylation status. Bisulfite sequencing demonstrated that the level of methylation of the promoters in different tissues correlates with Epac2 isoform expression. The presented data indicate that the tissue-specific expression of the Epac2 isoforms is epigenetically regulated, and identify tissue-specific differentially methylated promoter regions within the Epac2 locus that are essential for its transcriptional control.
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Affiliation(s)
- Erling A. Hoivik
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Clinical Medicine, Section for Gynecology and Obstetrics, University of Bergen, Bergen, Norway
| | | | | | - Yunjian Xu
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Ida Jakobsson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Anders Tengholm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | | | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
- * E-mail:
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Chepurny OG, Bertinetti D, Diskar M, Leech CA, Afshari P, Tsalkova T, Cheng X, Schwede F, Genieser HG, Herberg FW, Holz GG. Stimulation of proglucagon gene expression by human GPR119 in enteroendocrine L-cell line GLUTag. Mol Endocrinol 2013; 27:1267-82. [PMID: 23798572 DOI: 10.1210/me.2013-1029] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
GPR119 is a G protein-coupled receptor expressed on enteroendocrine L-cells that synthesize and secrete the incretin hormone glucagon-like peptide-1 (GLP-1). Although GPR119 agonists stimulate L-cell GLP-1 secretion, there is uncertainty concerning whether GLP-1 biosynthesis is under the control of GPR119. Here we report that GPR119 is functionally coupled to increased proglucagon (PG) gene expression that constitutes an essential first step in GLP-1 biosynthesis. Using a mouse L-cell line (GLUTag) that expresses endogenous GPR119, we demonstrate that PG gene promoter activity is stimulated by GPR119 agonist AS1269574. Surprisingly, transfection of GLUTag cells with recombinant human GPR119 (hGPR119) results in a constitutive and apparently ligand-independent increase of PG gene promoter activity and PG mRNA content. These constitutive actions of hGPR119 are mediated by cAMP-dependent protein kinase (PKA) but not cAMP sensor Epac2. Thus, the constitutive action of hGPR119 to stimulate PG gene promoter activity is diminished by: 1) a dominant-negative Gαs protein, 2) a dominant-negative PKA regulatory subunit, and 3) a dominant-negative A-CREB. Interestingly, PG gene promoter activity is stimulated by 6-Bn-cAMP-AM, a cAMP analog that selectively activates α and β isoforms of type II, but not type I PKA regulatory subunits expressed in GLUTag cells. Finally, our analysis reveals that a specific inhibitor of Epac2 activation (ESI-05) fails to block the stimulatory action of 6-Bn-cAMP-AM at the PG gene promoter, nor is PG gene promoter activity stimulated by: 1) a constitutively active Epac2, or 2) cAMP analogs that selectively activate Epac proteins. Such findings are discussed within the context of ongoing controversies concerning the relative contributions of PKA and Epac2 to the control of PG gene expression.
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Affiliation(s)
- Oleg G Chepurny
- Department of Medicine, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA
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Idevall-Hagren O, Jakobsson I, Xu Y, Tengholm A. Spatial control of Epac2 activity by cAMP and Ca2+-mediated activation of Ras in pancreatic β cells. Sci Signal 2013; 6:ra29.1-11, S1-6. [PMID: 23633676 DOI: 10.1126/scisignal.2003932] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The cAMP (adenosine 3',5'-monophosphate)-activated guanine nucleotide exchange factor (GEF) Epac2 is an important mediator of cAMP-dependent processes in multiple cell types. We used real-time confocal and total internal reflection fluorescence microscopy to examine the spatiotemporal regulation of Epac2, which is a GEF for the guanosine triphosphatase (GTPase) Rap. We demonstrated that increases in the concentration of cAMP triggered the translocation of Epac2 from the cytoplasm to the plasma membrane in insulin-secreting β cells. Glucose-induced oscillations of the submembrane concentration of cAMP were associated with cyclic translocation of Epac2, and this translocation could be amplified by increases in the cytoplasmic Ca(2+) concentration. Analyses of Epac2 mutants identified the high-affinity cAMP-binding and the Ras association domains as crucial for the translocation. Expression of a dominant-negative Ras mutant reduced Epac2 translocation, and Ca(2+)-dependent oscillations in Ras activity synchronized with Epac2 translocation in single β cells. The cyclic translocation of Epac2 was accompanied by oscillations of Rap GTPase activity at the plasma membrane, and expression of an inactive Rap1B mutant decreased insulin secretion. Thus, Epac2 localization is dynamically controlled by cAMP as well as by Ca(2+)-mediated activation of Ras. These results help to explain how oscillating signals can produce pulses of insulin release from pancreatic β cells.
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Affiliation(s)
- Olof Idevall-Hagren
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, SE-751 23 Uppsala, Sweden
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Patel M, Côté JF. Ras GTPases' interaction with effector domains: Breaking the families' barrier. Commun Integr Biol 2013; 6:e24298. [PMID: 23986800 PMCID: PMC3737747 DOI: 10.4161/cib.24298] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 03/13/2013] [Accepted: 03/14/2013] [Indexed: 01/01/2023] Open
Abstract
The Ras superfamily of proteins consists of five branches: Ras, Rho, Arf, Rab and Ran subfamilies. These proteins are involved in a plethora of biological functions spanning cytoskeletal organization, cell proliferation, transcription and intracellular trafficking. Ras-Binding Domains (RBDs) have classically been identified as autonomous ubiquitin-like folded regions that bind certain activated Ras GTPases of the Ras subfamily. In general, RBDs in many proteins have been tagged with membrane-targeting functions as in the case of the well-characterized c-Raf-RBD/Ras interaction. However, it is becoming apparent that the definition and functions of RBDs need to be revamped in order to reflect the new discoveries associated with this domain. Here, we discuss in more detail the recent advances associated with these RBDs. We highlight research identifying RBDs in formins, ELMOs and the RhoGEF, Syx and discuss the emerging role for RBDs in controlling autoinhibition relief and the newly recognized versatility of RBDs to interact with Rho and Arf family GTPases. In addition, these recent findings raise the exciting hypothesis that functional RBDs remain hidden in the proteome and are ready to be uncovered.
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Affiliation(s)
- Manishha Patel
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC Canada
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Schmidt M, Dekker FJ, Maarsingh H. Exchange protein directly activated by cAMP (epac): a multidomain cAMP mediator in the regulation of diverse biological functions. Pharmacol Rev 2013; 65:670-709. [PMID: 23447132 DOI: 10.1124/pr.110.003707] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Since the discovery nearly 60 years ago, cAMP is envisioned as one of the most universal and versatile second messengers. The tremendous feature of cAMP to tightly control highly diverse physiologic processes, including calcium homeostasis, metabolism, secretion, muscle contraction, cell fate, and gene transcription, is reflected by the award of five Nobel prizes. The discovery of Epac (exchange protein directly activated by cAMP) has ignited a new surge of cAMP-related research and has depicted novel cAMP properties independent of protein kinase A and cyclic nucleotide-gated channels. The multidomain architecture of Epac determines its activity state and allows cell-type specific protein-protein and protein-lipid interactions that control fine-tuning of pivotal biologic responses through the "old" second messenger cAMP. Compartmentalization of cAMP in space and time, maintained by A-kinase anchoring proteins, phosphodiesterases, and β-arrestins, contributes to the Epac signalosome of small GTPases, phospholipases, mitogen- and lipid-activated kinases, and transcription factors. These novel cAMP sensors seem to implement certain unexpected signaling properties of cAMP and thereby to permit delicate adaptations of biologic responses. Agonists and antagonists selective for Epac are developed and will support further studies on the biologic net outcome of the activation of Epac. This will increase our current knowledge on the pathophysiology of devastating diseases, such as diabetes, cognitive impairment, renal and heart failure, (pulmonary) hypertension, asthma, and chronic obstructive pulmonary disease. Further insights into the cAMP dynamics executed by the Epac signalosome will help to optimize the pharmacological treatment of these diseases.
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Affiliation(s)
- Martina Schmidt
- Department of Molecular Pharmacology, Groningen Research Institute for Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands.
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Berthouze-Duquesnes M, Lucas A, Saulière A, Sin YY, Laurent AC, Galés C, Baillie G, Lezoualc'h F. Specific interactions between Epac1, β-arrestin2 and PDE4D5 regulate β-adrenergic receptor subtype differential effects on cardiac hypertrophic signaling. Cell Signal 2012; 25:970-80. [PMID: 23266473 DOI: 10.1016/j.cellsig.2012.12.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 12/17/2012] [Indexed: 12/24/2022]
Abstract
β1 and β2 adrenergic receptors (βARs) are highly homologous but fulfill distinct physiological and pathophysiological roles. Here we show that both βAR subtypes activate the cAMP-binding protein Epac1, but they differentially affect its signaling. The distinct effects of βARs on Epac1 downstream effectors, the small G proteins Rap1 and H-Ras, involve different modes of interaction of Epac1 with the scaffolding protein β-arrestin2 and the cAMP-specific phosphodiesterase (PDE) variant PDE4D5. We found that β-arrestin2 acts as a scaffold for Epac1 and is necessary for Epac1 coupling to H-Ras. Accordingly, knockdown of β-arrestin2 prevented Epac1-induced histone deacetylase 4 (HDAC4) nuclear export and cardiac myocyte hypertrophy upon β1AR activation. Moreover, Epac1 competed with PDE4D5 for interaction with β-arrestin2 following β2AR activation. Dissociation of the PDE4D5-β-arrestin2 complex allowed the recruitment of Epac1 to β2AR and induced a switch from β2AR non-hypertrophic signaling to a β1AR-like pro-hypertrophic signaling cascade. These findings have implications for understanding the molecular basis of cardiac myocyte remodeling and other cellular processes in which βAR subtypes exert opposing effects.
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MESH Headings
- Animals
- Arrestins/antagonists & inhibitors
- Arrestins/genetics
- Arrestins/metabolism
- Cardiomegaly/metabolism
- Cardiomegaly/pathology
- Cells, Cultured
- Cyclic Nucleotide Phosphodiesterases, Type 3/metabolism
- Cyclic Nucleotide Phosphodiesterases, Type 4
- Fluorescence Resonance Energy Transfer
- Guanine Nucleotide Exchange Factors/metabolism
- HEK293 Cells
- Humans
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/metabolism
- Protein Interaction Maps
- Proto-Oncogene Proteins p21(ras)/metabolism
- RNA Interference
- RNA, Small Interfering/metabolism
- Rats
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/metabolism
- Signal Transduction
- beta-Arrestins
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Affiliation(s)
- Magali Berthouze-Duquesnes
- Inserm, UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, 31432 Toulouse Cedex 04, France
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Oldenburger A, Maarsingh H, Schmidt M. Multiple facets of cAMP signalling and physiological impact: cAMP compartmentalization in the lung. Pharmaceuticals (Basel) 2012; 5:1291-331. [PMID: 24281338 PMCID: PMC3816672 DOI: 10.3390/ph5121291] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/15/2012] [Accepted: 11/20/2012] [Indexed: 12/20/2022] Open
Abstract
Therapies involving elevation of the endogenous suppressor cyclic AMP (cAMP) are currently used in the treatment of several chronic inflammatory disorders, including chronic obstructive pulmonary disease (COPD). Characteristics of COPD are airway obstruction, airway inflammation and airway remodelling, processes encompassed by increased airway smooth muscle mass, epithelial changes, goblet cell and submucosal gland hyperplasia. In addition to inflammatory cells, airway smooth muscle cells and (myo)fibroblasts, epithelial cells underpin a variety of key responses in the airways such as inflammatory cytokine release, airway remodelling, mucus hypersecretion and airway barrier function. Cigarette smoke, being next to environmental pollution the main cause of COPD, is believed to cause epithelial hyperpermeability by disrupting the barrier function. Here we will focus on the most recent progress on compartmentalized signalling by cAMP. In addition to G protein-coupled receptors, adenylyl cyclases, cAMP-specific phospho-diesterases (PDEs) maintain compartmentalized cAMP signalling. Intriguingly, spatially discrete cAMP-sensing signalling complexes seem also to involve distinct members of the A-kinase anchoring (AKAP) superfamily and IQ motif containing GTPase activating protein (IQGAPs). In this review, we will highlight the interaction between cAMP and the epithelial barrier to retain proper lung function and to alleviate COPD symptoms and focus on the possible molecular mechanisms involved in this process. Future studies should include the development of cAMP-sensing multiprotein complex specific disruptors and/or stabilizers to orchestrate cellular functions. Compartmentalized cAMP signalling regulates important cellular processes in the lung and may serve as a therapeutic target.
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Affiliation(s)
- Anouk Oldenburger
- Department of Molecular Pharmacology, Groningen Research Institute for Pharmacy, University of Groningen, 9713 AV, Groningen, The Netherlands.
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Dekkers BGJ, Racké K, Schmidt M. Distinct PKA and Epac compartmentalization in airway function and plasticity. Pharmacol Ther 2012; 137:248-65. [PMID: 23089371 DOI: 10.1016/j.pharmthera.2012.10.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 10/09/2012] [Indexed: 12/15/2022]
Abstract
Asthma and chronic obstructive pulmonary disease (COPD) are obstructive lung diseases characterized by airway obstruction, airway inflammation and airway remodelling. Next to inflammatory cells and airway epithelial cells, airway mesenchymal cells, including airway smooth muscle cells and (myo)fibroblasts, substantially contribute to disease features by the release of inflammatory mediators, smooth muscle contraction, extracellular matrix deposition and structural changes in the airways. Current pharmacological treatment of both diseases intends to target the dynamic features of the endogenous intracellular suppressor cyclic AMP (cAMP). This review will summarize our current knowledge on cAMP and will emphasize on key discoveries and paradigm shifts reflecting the complex spatio-temporal nature of compartmentalized cAMP signalling networks in health and disease. As airway fibroblasts and airway smooth muscle cells are recognized as central players in the development and progression of asthma and COPD, we will focus on the role of cAMP signalling in their function in relation to airway function and plasticity. We will recapture on the recent identification of cAMP-sensing multi-protein complexes maintained by cAMP effectors, including A-kinase anchoring proteins (AKAPs), proteins kinase A (PKA), exchange protein directly activated by cAMP (Epac), cAMP-elevating seven-transmembrane (7TM) receptors and phosphodiesterases (PDEs) and we will report on findings indicating that the pertubation of compartmentalized cAMP signalling correlates with the pathopysiology of obstructive lung diseases. Future challenges include studies on cAMP dynamics and compartmentalization in the lung and the development of novel drugs targeting these systems for therapeutic interventions in chronic obstructive inflammatory diseases.
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Affiliation(s)
- Bart G J Dekkers
- Department of Molecular Pharmacology, University Center of Pharmacy, University of Groningen, The Netherlands.
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Tada M, Gengyo-Ando K, Kobayashi T, Fukuyama M, Mitani S, Kontani K, Katada T. Neuronally expressed Ras-family GTPase Di-Ras modulates synaptic activity in Caenorhabditis elegans. Genes Cells 2012; 17:778-89. [PMID: 22897658 DOI: 10.1111/j.1365-2443.2012.01627.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 06/14/2012] [Indexed: 10/28/2022]
Abstract
Ras-family GTPases regulate a wide variety of cellular functions including cell growth and differentiation. Di-Ras, which belongs to a distinct subfamily of Ras-family GTPases, is expressed predominantly in brain, but the role of Di-Ras in nervous systems remains totally unknown. Here, we report that the Caenorhabditis elegans Di-Ras homologue drn-1 is expressed specifically in neuronal cells and involved in synaptic function at neuromuscular junctions. Loss of function of drn-1 conferred resistance to the acetylcholinesterase inhibitor aldicarb and partially suppressed the aldicarb-hypersensitive phenotypes of heterotrimeric G-protein mutants, in which acetylcholine release is up-regulated. drn-1 mutants displayed no apparent defects in the axonal distribution of the membrane-bound second messenger diacylglycerol (DAG), which is a key stimulator of acetylcholine release. Finally, we have identified EPAC-1, a C. elegans Epac homologue, as a binding partner for DRN-1. Deletion mutants of epac-1 displayed an aldicarb-resistant phenotype as drn-1 mutants. Genetic analysis of drn-1 and epac-1 showed that they acted in the same pathway to control acetylcholine release. Furthermore, DRN-1 and EPAC-1 were co-immunoprecipitated. These findings suggest that DRN-1 may function cooperatively with EPAC-1 to modulate synaptic activity in C. elegans.
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Affiliation(s)
- Minoru Tada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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Seino S. Cell signalling in insulin secretion: the molecular targets of ATP, cAMP and sulfonylurea. Diabetologia 2012; 55:2096-108. [PMID: 22555472 DOI: 10.1007/s00125-012-2562-9] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 03/09/2012] [Indexed: 12/25/2022]
Abstract
Clarification of the molecular mechanisms of insulin secretion is crucial for understanding the pathogenesis and pathophysiology of diabetes and for development of novel therapeutic strategies for the disease. Insulin secretion is regulated by various intracellular signals generated by nutrients and hormonal and neural inputs. In addition, a variety of glucose-lowering drugs including sulfonylureas, glinide-derivatives, and incretin-related drugs such as dipeptidyl peptidase IV (DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists are used for glycaemic control by targeting beta cell signalling for improved insulin secretion. There has been a remarkable increase in our understanding of the basis of beta cell signalling over the past two decades following the application of molecular biology, gene technology, electrophysiology and bioimaging to beta cell research. This review discusses cell signalling in insulin secretion, focusing on the molecular targets of ATP, cAMP and sulfonylurea, an essential metabolic signal in glucose-induced insulin secretion (GIIS), a critical signal in the potentiation of GIIS, and the commonly used glucose-lowering drug, respectively.
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Affiliation(s)
- S Seino
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, 650-0017, Japan.
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41
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Srivastava DP, Woolfrey KM, Jones KA, Anderson CT, Smith KR, Russell TA, Lee H, Yasvoina MV, Wokosin DL, Ozdinler PH, Shepherd GMG, Penzes P. An autism-associated variant of Epac2 reveals a role for Ras/Epac2 signaling in controlling basal dendrite maintenance in mice. PLoS Biol 2012; 10:e1001350. [PMID: 22745599 PMCID: PMC3383751 DOI: 10.1371/journal.pbio.1001350] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 05/15/2012] [Indexed: 11/19/2022] Open
Abstract
The architecture of dendritic arbors determines circuit connectivity, receptive fields, and computational properties of neurons, and dendritic structure is impaired in several psychiatric disorders. While apical and basal dendritic compartments of pyramidal neurons are functionally specialized and differentially regulated, little is known about mechanisms that selectively maintain basal dendrites. Here we identified a role for the Ras/Epac2 pathway in maintaining basal dendrite complexity of cortical neurons. Epac2 is a guanine nucleotide exchange factor (GEF) for the Ras-like small GTPase Rap, and it is highly enriched in the adult mouse brain. We found that in vivo Epac2 knockdown in layer 2/3 cortical neurons via in utero electroporation reduced basal dendritic architecture, and that Epac2 knockdown in mature cortical neurons in vitro mimicked this effect. Overexpression of an Epac2 rare coding variant, found in human subjects diagnosed with autism, also impaired basal dendritic morphology. This mutation disrupted Epac2's interaction with Ras, and inhibition of Ras selectively interfered with basal dendrite maintenance. Finally, we observed that components of the Ras/Epac2/Rap pathway exhibited differential abundance in the basal versus apical dendritic compartments. These findings define a role for Epac2 in enabling crosstalk between Ras and Rap signaling in maintaining basal dendrite complexity, and exemplify how rare coding variants, in addition to their disease relevance, can provide insight into cellular mechanisms relevant for brain connectivity.
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Affiliation(s)
- Deepak P. Srivastava
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Neuroscience & Centre for the Cellular Basis of Behaviour, The James Black Centre, King's College London, Institute of Psychiatry, London, United Kingdom
| | - Kevin M. Woolfrey
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Kelly A. Jones
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Charles T. Anderson
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Katharine R. Smith
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Theron A. Russell
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Hyerin Lee
- Weinberg College of Arts and Sciences, Northwestern University, Evanston, Illinois, United States of America
| | - Marina V. Yasvoina
- Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - David L. Wokosin
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - P. Hande Ozdinler
- Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Cognitive Neurology and Disease Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Lurie Cancer Research Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Gordon M. G. Shepherd
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Lurie Cancer Research Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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Abstract
Prostaglandin E(2) (PGE(2)), a cyclooxygenase (COX) product, is the best known lipid mediator that contributes to inflammatory pain. Nonsteroidal anti-inflammatory drugs (NSAIDs), inhibitors of COX-1 and/or COX-2, suppress inflammatory pain by reducing generation of prostanoids, mainly PGE(2), while they exhibit gastrointestinal, renal and cardiovascular toxicities. Selective inhibitors of microsomal PGE synthase-1 and subtype-selective antagonists of PGE(2) receptors, particularly EP(1) and EP(4), may be useful as analgesics with minimized side-effects. Protein kinase C (PKC) and PKA downstream of EP(1) and EP(4), respectively, sensitize/activate multiple molecules including transient receptor potential vanilloid-1 (TRPV1) channels, purinergic P2X3 receptors, and voltage-gated calcium or sodium channels in nociceptors, leading to hyperalgesia. PGE(2) is also implicated in neuropathic and visceral pain and in migraine. Thus, PGE(2) has a great impact on pain signals, and pharmacological intervention in upstream and downstream signals of PGE(2) may serve as novel therapeutic strategies for the treatment of intractable pain.
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Affiliation(s)
- Atsufumi Kawabata
- Division of Pharmacology and Pathophysiology, School of Pharmacy, Kinki University, Higashi-Osaka 577–8502, Japan.
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43
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Kepner EM, Yoder SM, Oh E, Kalwat MA, Wang Z, Quilliam LA, Thurmond DC. Cool-1/βPIX functions as a guanine nucleotide exchange factor in the cycling of Cdc42 to regulate insulin secretion. Am J Physiol Endocrinol Metab 2011; 301:E1072-80. [PMID: 21828338 PMCID: PMC3233779 DOI: 10.1152/ajpendo.00312.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 08/03/2011] [Indexed: 11/22/2022]
Abstract
Second-phase insulin release requires the sustained mobilization of insulin granules from internal storage pools to the cell surface for fusion with the plasma membrane. However, the detailed mechanisms underlying this process remain largely unknown. GTP-loading of the small GTPase Cdc42 is the first glucose-specific activation step in the process, although how glucose triggers Cdc42 activation is entirely unknown. In a directed candidate screen for guanine nucleotide exchange factors (GEFs), which directly activate small GTPases, Cool-1/βPix was identified in pancreatic islet beta cells. In support of its role as the beta cell Cdc42 GEF, βPix coimmunoprecipitated with Cdc42 in human islets and MIN6 beta cells in a glucose-dependent manner, peaking just prior to Cdc42 activation. Furthermore, RNAi-mediated βPix reduction by 50% corresponded to full ablation of glucose-induced Cdc42 activation and significant attenuation of basal and glucose-stimulated insulin secretion. Of the two Cdc42 guanine nucleotide dissociation inhibitor (GDI) proteins identified in beta cells, βPix competed selectively with caveolin-1 (Cav-1) but not RhoGDI in coimmunoprecipitation and GST-Cdc42-GDP interaction assays. However, a phospho-deficient Cav-1-Y14F mutant failed to compete with βPix; Cav-1(Tyr14) is an established phosphorylation site for Src kinase. Taken together, these data support a new model, wherein glucose stimulates Cav-1 and induces its dissociation from Cdc42, possibly via Src kinase activation to phosphorylate Cav-1(Tyr14), to promote Cdc42-βPix binding and Cdc42 activation, and to trigger downstream signaling and ultimately sustain insulin release.
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Affiliation(s)
- Erica M Kepner
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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44
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Stangherlin A, Zaccolo M. Phosphodiesterases and subcellular compartmentalized cAMP signaling in the cardiovascular system. Am J Physiol Heart Circ Physiol 2011; 302:H379-90. [PMID: 22037184 DOI: 10.1152/ajpheart.00766.2011] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Phosphodiesterases are key enzymes in the cAMP signaling cascade. They convert cAMP in its inactive form 5'-AMP and critically regulate the intensity and the duration of cAMP-mediated signals. Multiple isoforms exist that possess different intracellular distributions, different affinities for cAMP, and different catalytic and regulatory properties. This complex repertoire of enzymes provides a multiplicity of ways to modulate cAMP levels, to integrate more signaling pathways, and to respond to the specific needs of the cell within distinct subcellular domains. In this review we summarize key findings on phosphodiesterase compartmentalization in the cardiovascular system.
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Affiliation(s)
- Alessandra Stangherlin
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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45
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Edwards HV, Christian F, Baillie GS. cAMP: novel concepts in compartmentalised signalling. Semin Cell Dev Biol 2011; 23:181-90. [PMID: 21930230 DOI: 10.1016/j.semcdb.2011.09.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 09/08/2011] [Indexed: 12/12/2022]
Abstract
Cyclic adenosine 3,'5'-monophosphate (cAMP) is the archetypal second messenger produced at the membrane by adenylyl cyclase following activation of many different G protein-coupled receptor (GPCR) types. Although discovered over fifty years ago, the notion that cAMP responses were compartmentalised was born in the 1980s. Since then, modern molecular techniques have facilitated visualisation of cellular cAMP dynamics in real time and helped us to understand how a single, ubiquitous second messenger can direct receptor-specific functions in cells. The aim of this review is to highlight emerging ideas in the cAMP field that are currently developing the concept of compartmentalised cAMP signalling systems.
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Affiliation(s)
- Helen V Edwards
- Institute of Neuroscience and Molecular Pharmacology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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46
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Gloerich M, Bos JL. Regulating Rap small G-proteins in time and space. Trends Cell Biol 2011; 21:615-23. [PMID: 21820312 DOI: 10.1016/j.tcb.2011.07.001] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 06/29/2011] [Accepted: 07/05/2011] [Indexed: 11/25/2022]
Abstract
Signaling by the small G-protein Rap is under tight regulation by its GEFs and GAPs. These are multi-domain proteins that are themselves controlled by distinct upstream pathways, and thus couple different extra- and intracellular cues to Rap. The individual RapGEFs and RapGAPs are, in addition, targeted to specific cellular locations by numerous anchoring mechanisms and, consequently, may control different pools of Rap. Here, we review the various activating signals and targeting mechanisms of these proteins and discuss their contribution to the spatiotemporal regulation and biological functions of the Rap proteins.
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Affiliation(s)
- Martijn Gloerich
- Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Utrecht, The Netherlands
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47
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Rap-linked cAMP signaling Epac proteins: Compartmentation, functioning and disease implications. Cell Signal 2011; 23:1257-66. [DOI: 10.1016/j.cellsig.2011.03.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/04/2011] [Accepted: 03/04/2011] [Indexed: 12/14/2022]
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48
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Takeda Y, Amano A, Noma A, Nakamura Y, Fujimoto S, Inagaki N. Systems analysis of GLP-1 receptor signaling in pancreatic β-cells. Am J Physiol Cell Physiol 2011; 301:C792-803. [PMID: 21734192 DOI: 10.1152/ajpcell.00057.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) elevates intracellular concentration of cAMP ([cAMP]) and facilitates glucose-dependent insulin secretion in pancreatic β-cells. There has been much evidence to suggest that multiple key players such as the GLP-1 receptor, G(s) protein, adenylate cyclase (AC), phosphodiesterase (PDE), and intracellular Ca(2+) concentration ([Ca(2+)]) are involved in the regulation of [cAMP]. However, because of complex interactions among these signaling factors, the kinetics of the reaction cascade as well as the activities of ACs and PDEs have not been determined in pancreatic β-cells. We have constructed a minimal mathematical model of GLP-1 receptor signal transduction based on experimental findings obtained mostly in β-cells and insulinoma cell lines. By fitting this theoretical reaction scheme to key experimental records of the GLP-1 response, the parameters determining individual reaction steps were estimated. The model reconstructed satisfactorily the dynamic changes in [cAMP] and predicted the activities of cAMP effectors, protein kinase A (PKA), and cAMP-regulated guanine nucleotide exchange factor [cAMP-GEF or exchange protein directly activated by cAMP (Epac)] during GLP-1 stimulation. The simulations also predicted the presence of two sequential desensitization steps of the GLP1 receptor that occur with fast and very slow reaction rates. The cross talk between glucose- and GLP-1-dependent signal cascades for cAMP synthesis was well reconstructed by integrating the direct regulation of AC and PDE by [Ca(2+)]. To examine robustness of the signaling system in controlling [cAMP], magnitudes of AC and PDE activities were compared in the presence or absence of GLP-1 and/or the PDE inhibitor IBMX.(1).
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Affiliation(s)
- Yukari Takeda
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Japan
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49
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Popiolek M, Ross JF, Charych E, Chanda P, Gundelfinger ED, Moss SJ, Brandon NJ, Pausch MH. D-amino acid oxidase activity is inhibited by an interaction with bassoon protein at the presynaptic active zone. J Biol Chem 2011; 286:28867-28875. [PMID: 21700703 DOI: 10.1074/jbc.m111.262063] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Schizophrenia is a highly heritable neuropsychiatric disorder affecting ∼1% of the world's population. Linkage and association studies have identified multiple candidate schizophrenia susceptibility genes whose functions converge on the glutamatergic neurotransmitter system. One such susceptibility gene encoding D-amino acid oxidase (DAO), an enzyme that metabolizes the NMDA receptor (NMDAR) co-agonist D-serine, has the potential to modulate NMDAR function in the context of schizophrenia. To further investigate its cellular regulation, we sought to identify DAO-interacting proteins that participate in its functional regulation in rat cerebellum, where DAO expression is especially high. Immunoprecipitation with DAO-specific antibodies and subsequent mass spectrometric analysis of co-precipitated proteins yielded 24 putative DAO-interacting proteins. The most robust interactions occurred with known components of the presynaptic active zone, such as bassoon (BSN) and piccolo (PCLO). The interaction of DAO with BSN was confirmed through co-immunoprecipitation assays using DAO- and BSN-specific antibodies. Moreover, DAO and BSN colocalized with one another in cultured cerebellar granule cells and in synaptic junction membrane protein fractions derived from rat cerebellum. The functional consequences of this interaction were studied through enzyme assay experiments, where DAO enzymatic activity was significantly inhibited as a result of its interaction with BSN. Taking these results together, we hypothesize that synaptic D-serine concentrations may be under tight regulation by a BSN-DAO complex. We therefore predict that this mechanism plays a role in the modulation of glutamatergic signaling through NMDARs. It also furthers our understanding of the biology underlying this potential therapeutic entry point for schizophrenia and other psychiatric disorders.
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Affiliation(s)
- Michael Popiolek
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340
| | - John F Ross
- Aileron Therapeutics, Cambridge, Massachusetts, Germany
| | - Erik Charych
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Pranab Chanda
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340
| | | | | | - Nicholas J Brandon
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340,.
| | - Mark H Pausch
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340,; Merck, West Point, Pennsylvania 19486
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50
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Pertuit M, Romano D, Zeiller C, Barlier A, Enjalbert A, Gerard C. The gsp oncogene disrupts Ras/ERK-dependent prolactin gene regulation in gsp inducible somatotroph cell line. Endocrinology 2011; 152:1234-43. [PMID: 21285319 DOI: 10.1210/en.2010-1077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The MAPK ERK1/2 cascade regulates all the critical cellular functions, and in many pathological situations, these regulatory processes are perturbed. It has been clearly established that this cascade is an integrative point in the control of the pituitary functions exerted by various extracellular signals. In particular, ERK1/2 cross talk with the cAMP pathway is determinant in the control of somatolactotroph hormonal secretion exerted via neuropeptide receptors. GH-secreting adenomas are characterized by frequent cAMP pathway alterations, such as constitutive activation of the α-subunit of the heterotrimeric Gs protein (the gsp oncogene), overexpression of Gsα, and changes in the protein kinase A regulatory subunits. However, it has not yet been established exactly how these alterations result in GH-secreting adenomas or how the ERK1/2 cascade contributes to the process of GH-secreting adenoma tumorigenesis. In this study on the conditional gsp-oncogene-expressing GH4C1 cell line, expression of the gsp oncogene, which was observed in up to 40% of GH-secreting adenomas, was found to induce sustained ERK1/2 activation, which required activation of the protein kinase A and the GTPases Ras and Rap1. All these signaling components contribute to the chronic activation of the human prolactin promoter. The data obtained here show that Ras plays a crucial role in these processes: in a physiopathological context, i.e. in the presence of the gsp oncogene, it switched from being a repressor of the cAMP/ protein kinase A ERK-sensitive prolactin gene control exerted by neuropeptides to an activator of the prolactin promoter.
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Affiliation(s)
- M Pertuit
- CRN2M, Unité Mixte de Recherche 6231, Department of Neuroendocrinology-Neuroimmunology, Institut Fédératif Jean-Roche, Faculté de Médecine Secteur Nord, Université de la Méditerranée CS80011, Boulevard Pierre Dramard, 13344 Marseille cedex 15, France
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