51
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Tepikin AV. Mitochondrial signalling, physiology and pathophysiology. Pflugers Arch 2018; 470:1139-1140. [PMID: 29961147 DOI: 10.1007/s00424-018-2172-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/15/2018] [Accepted: 06/20/2018] [Indexed: 12/01/2022]
Affiliation(s)
- Alexei V Tepikin
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK.
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52
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Vallin B, Legueux-Cajgfinger Y, Clément N, Glorian M, Duca L, Vincent P, Limon I, Blaise R. Novel short isoforms of adenylyl cyclase as negative regulators of cAMP production. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1326-1340. [PMID: 29940197 DOI: 10.1016/j.bbamcr.2018.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 06/15/2018] [Accepted: 06/20/2018] [Indexed: 12/22/2022]
Abstract
Here, we cloned a new family of four adenylyl cyclase (AC) splice variants from interleukin-1β (IL-1β)-transdifferentiated vascular smooth muscle cells (VSMCs) encoding short forms of AC8 that we have named "AC8E-H". Using biosensor imaging and biochemical approaches, we showed that AC8E-H isoforms have no cyclase activity and act as dominant-negative regulators by forming heterodimers with other full-length ACs, impeding the traffic of functional units towards the plasma membrane. The existence of these dominant-negative isoforms may account for an unsuspected additional degree of cAMP signaling regulation. It also reconciles the induction of an AC in transdifferentiated VSMCs with the vasoprotective influence of cAMP. The generation of alternative splice variants of ACs may constitute a generalized strategy of adaptation to the cell's environment whose scope had so far been ignored in physiological and/or pathological contexts.
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Affiliation(s)
- Benjamin Vallin
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France
| | - Yohan Legueux-Cajgfinger
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France
| | - Nathalie Clément
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France
| | - Martine Glorian
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France
| | - Laurent Duca
- UFR Sciences Exactes et Naturelles, Université de Reims Champagne Ardenne (URCA), UMR CNRS 7369 Matrice Extracellulaire et Dynamique Cellulaire (MEDyC), Laboratoire Signalisation et Récepteurs Matriciels (SiRMa), Campus Moulin de la Housse, 51687 Reims, France
| | - Pierre Vincent
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France.
| | - Isabelle Limon
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France.
| | - Régis Blaise
- Sorbonne Université, Université Pierre et Marie Curie (UPMC), Institut de Biologie Paris-Seine (IBPS), UMR CNRS 8256 Adaptation biologique et vieillissement (B2A), 75005 Paris, France
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53
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Bak LK, Walls AB, Schousboe A, Waagepetersen HS. Astrocytic glycogen metabolism in the healthy and diseased brain. J Biol Chem 2018; 293:7108-7116. [PMID: 29572349 DOI: 10.1074/jbc.r117.803239] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The brain contains a fairly low amount of glycogen, mostly located in astrocytes, a fact that has prompted the suggestion that glycogen does not have a significant physiological role in the brain. However, glycogen metabolism in astrocytes is essential for several key physiological processes and is adversely affected in disease. For instance, diminished ability to break down glycogen impinges on learning, and epilepsy, Alzheimer's disease, and type 2 diabetes are all associated with abnormal astrocyte glycogen metabolism. Glycogen metabolism supports astrocytic K+ and neurotransmitter glutamate uptake and subsequent glutamine synthesis-three fundamental steps in excitatory signaling at most brain synapses. Thus, there is abundant evidence for a key role of glycogen in brain function. Here, we summarize the physiological brain functions that depend on glycogen, discuss glycogen metabolism in disease, and investigate how glycogen breakdown is regulated at the cellular and molecular levels.
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Affiliation(s)
- Lasse K Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark.
| | - Anne B Walls
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark
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54
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Soboloff J, Gligorijevic B, Zaidi MR. STIM1 (c)AMPs up melanogenesis. EMBO J 2018; 37:embj.201899047. [PMID: 29449324 DOI: 10.15252/embj.201899047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jonathan Soboloff
- Fels Institute for Cancer Research and Molecular Biology, Temple University, Philadelphia, PA, USA
| | | | - M Raza Zaidi
- Fels Institute for Cancer Research and Molecular Biology, Temple University, Philadelphia, PA, USA
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55
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Motiani RK, Tanwar J, Raja DA, Vashisht A, Khanna S, Sharma S, Srivastava S, Sivasubbu S, Natarajan VT, Gokhale RS. STIM1 activation of adenylyl cyclase 6 connects Ca 2+ and cAMP signaling during melanogenesis. EMBO J 2018; 37:embj.201797597. [PMID: 29311116 DOI: 10.15252/embj.201797597] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 11/29/2017] [Accepted: 12/06/2017] [Indexed: 11/09/2022] Open
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) junctions form functionally active microdomains that connect intracellular and extracellular environments. While the key role of these interfaces in maintenance of intracellular Ca2+ levels has been uncovered in recent years, the functional significance of ER-PM junctions in non-excitable cells has remained unclear. Here, we show that the ER calcium sensor protein STIM1 (stromal interaction molecule 1) interacts with the plasma membrane-localized adenylyl cyclase 6 (ADCY6) to govern melanogenesis. The physiological stimulus α-melanocyte-stimulating hormone (αMSH) depletes ER Ca2+ stores, thus recruiting STIM1 to ER-PM junctions, which in turn activates ADCY6. Using zebrafish as a model system, we further established STIM1's significance in regulating pigmentation in vivo STIM1 domain deletion studies reveal the importance of Ser/Pro-rich C-terminal region in this interaction. This mechanism of cAMP generation creates a positive feedback loop, controlling the output of the classical αMSH-cAMP-MITF axis in melanocytes. Our study thus delineates a signaling module that couples two fundamental secondary messengers to drive pigmentation. Given the central role of calcium and cAMP signaling pathways, this module may be operative during various other physiological processes and pathological conditions.
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Affiliation(s)
- Rajender K Motiani
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Jyoti Tanwar
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Desingu Ayyappa Raja
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.,Academy of Scientific and Innovative Research, New Delhi, India
| | - Ayushi Vashisht
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Shivangi Khanna
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.,Academy of Scientific and Innovative Research, New Delhi, India
| | - Sachin Sharma
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.,Academy of Scientific and Innovative Research, New Delhi, India
| | - Sonali Srivastava
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Sridhar Sivasubbu
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.,Academy of Scientific and Innovative Research, New Delhi, India
| | - Vivek T Natarajan
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.,Academy of Scientific and Innovative Research, New Delhi, India
| | - Rajesh S Gokhale
- Systems Biology Group, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
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56
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Putney JW. Forms and functions of store-operated calcium entry mediators, STIM and Orai. Adv Biol Regul 2017; 68:88-96. [PMID: 29217255 DOI: 10.1016/j.jbior.2017.11.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/20/2017] [Accepted: 11/20/2017] [Indexed: 12/31/2022]
Abstract
Calcium signals arise by multiple mechanisms, including mechanisms of release of intracellular stored Ca2+, and the influx of Ca2+ through channels in the plasma membrane. One mechanism that links these two sources of Ca2+ is store-operated Ca2+ entry, the most commonly encountered version of which involves the extensively studied calcium-release-activated Ca2+ (CRAC) channel. The minimal and essential molecular components of the CRAC channel are the STIM proteins that function as Ca2+ sensors in the endoplasmic reticulum, and the Orai proteins that comprise the pore forming subunits of the CRAC channel. CRAC channels are known to play significant roles in a wide variety of physiological functions. This review discusses the multiple forms of STIM and Orai proteins encountered in mammalian cells, and discusses some specific examples of how these proteins modulate or mediate important physiological processes.
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Affiliation(s)
- James W Putney
- National Institute of Environmental Health Sciences - NIH, Research Triangle Park, NC 27709, USA.
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57
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Muallem S, Chung WY, Jha A, Ahuja M. Lipids at membrane contact sites: cell signaling and ion transport. EMBO Rep 2017; 18:1893-1904. [PMID: 29030479 DOI: 10.15252/embr.201744331] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/10/2017] [Accepted: 09/21/2017] [Indexed: 12/14/2022] Open
Abstract
Communication between organelles is essential to coordinate cellular functions and the cell's response to physiological and pathological stimuli. Organellar communication occurs at membrane contact sites (MCSs), where the endoplasmic reticulum (ER) membrane is tethered to cellular organelle membranes by specific tether proteins and where lipid transfer proteins and cell signaling proteins are located. MCSs have many cellular functions and are the sites of lipid and ion transfer between organelles and generation of second messengers. This review discusses several aspects of MCSs in the context of lipid transfer, formation of lipid domains, generation of Ca2+ and cAMP second messengers, and regulation of ion transporters by lipids.
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Affiliation(s)
- Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, Bethesda, MD, USA
| | - Woo Young Chung
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, Bethesda, MD, USA
| | - Archana Jha
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, Bethesda, MD, USA
| | - Malini Ahuja
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, Bethesda, MD, USA
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58
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Maus M, Cuk M, Patel B, Lian J, Ouimet M, Kaufmann U, Yang J, Horvath R, Hornig-Do HT, Chrzanowska-Lightowlers ZM, Moore KJ, Cuervo AM, Feske S. Store-Operated Ca 2+ Entry Controls Induction of Lipolysis and the Transcriptional Reprogramming to Lipid Metabolism. Cell Metab 2017; 25:698-712. [PMID: 28132808 PMCID: PMC5342942 DOI: 10.1016/j.cmet.2016.12.021] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 09/01/2016] [Accepted: 12/28/2016] [Indexed: 12/26/2022]
Abstract
Ca2+ signals were reported to control lipid homeostasis, but the Ca2+ channels and pathways involved are largely unknown. Store-operated Ca2+ entry (SOCE) is a ubiquitous Ca2+ influx pathway regulated by stromal interaction molecule 1 (STIM1), STIM2, and the Ca2+ channel ORAI1. We show that SOCE-deficient mice accumulate pathological amounts of lipid droplets in the liver, heart, and skeletal muscle. Cells from patients with loss-of-function mutations in STIM1 or ORAI1 show a similar phenotype, suggesting a cell-intrinsic role for SOCE in the regulation of lipid metabolism. SOCE is crucial to induce mobilization of fatty acids from lipid droplets, lipolysis, and mitochondrial fatty acid oxidation. SOCE regulates cyclic AMP production and the expression of neutral lipases as well as the transcriptional regulators of lipid metabolism, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), and peroxisome proliferator-activated receptor α (PPARα). SOCE-deficient cells upregulate lipophagy, which protects them from lipotoxicity. Our data provide evidence for an important role of SOCE in lipid metabolism.
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Affiliation(s)
- Mate Maus
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Mario Cuk
- Department of Pediatrics, Zagreb University Hospital Centre and School of Medicine, 10 000 Zagreb, Croatia
| | - Bindi Patel
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jayson Lian
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Mireille Ouimet
- Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Ulrike Kaufmann
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Jun Yang
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Rita Horvath
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Hue-Tran Hornig-Do
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Zofia M Chrzanowska-Lightowlers
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Kathryn J Moore
- Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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59
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Spirli C, Mariotti V, Villani A, Fabris L, Fiorotto R, Strazzabosco M. Adenylyl cyclase 5 links changes in calcium homeostasis to cAMP-dependent cyst growth in polycystic liver disease. J Hepatol 2017; 66:571-580. [PMID: 27826057 PMCID: PMC5316496 DOI: 10.1016/j.jhep.2016.10.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 10/17/2016] [Accepted: 10/23/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Genetic defects in polycystin-1 or -2 (PC1 or PC2) cause polycystic liver disease associated with autosomal dominant polycystic kidney disease (PLD-ADPKD). Progressive cyst growth is sustained by a cAMP-dependent Ras/ERK/HIFα pathway, leading to increased vascular endothelial growth factor A (VEGF-A) signaling. In PC2-defective cholangiocytes, cAMP production in response to [Ca2+]ER depletion is increased, while store-operated Ca2+ entry (SOCE), intracellular and endoplasmic reticulum [Ca2+]ER levels are reduced. We investigated whether the adenylyl cyclases, AC5 and AC6, which can be inhibited by Ca2+, are activated by the ER chaperone STIM1. This would result in cAMP/PKA-dependent Ras/ERK/HIFα pathway activation in PC2-defective cells, in response to [Ca2+]ER depletion. METHODS PC2/AC6 double conditional knockout (KO) mice were generated (Pkd2/AC6 KO) and compared to Pkd2 KO mice. The AC5 inhibitor SQ22,536 or AC5 siRNA were used in isolated cholangiocytes while the inhibitor was used in biliary organoid and animals; liver tissues were harvested for histochemical analysis. RESULTS When comparing Pkd2/AC6 KO to Pkd2 KO mice, no decrease in liver cyst size was found, and cellular cAMP after [Ca2+]ER depletion only decreased by 12%. Conversely, in PC2-defective cells, inhibition of AC5 significantly reduced cAMP production, pERK1/2 expression and VEGF-A secretion. AC5 inhibitors significantly reduced growth of biliary organoids derived from Pkd2 KO and Pkd2/AC6 KO mice. In vivo treatment with SQ22,536 significantly reduced liver cystic area and cell proliferation in PC2-defective mice. After [Ca2+]ER depletion in PC2-defective cells, STIM1 interacts with AC5 but not with Orai1, the Ca2+ channel that mediates SOCE. CONCLUSION [Ca2+]ER depletion in PC2-defective cells activates AC5 and results in stimulation of cAMP/ERK1-2 signaling, VEGF production and cyst growth. This mechanism may represent a novel therapeutic target. LAY SUMMARY Polycystic liver diseases are characterized by progressive cyst growth until their complications mandate surgery or liver transplantation. In this manuscript, we demonstrate that inhibiting cell proliferation, which is induced by increased levels of cAMP, may represent a novel therapeutic target to slow the progression of the disease.
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Affiliation(s)
- Carlo Spirli
- Section of Digestive Diseases, Yale University, New Haven, Connecticut, USA
| | - Valeria Mariotti
- Section of Digestive Diseases, Yale University, New Haven, Connecticut, USA,Section of Digestive Diseases, International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Milan, Italy
| | - Ambra Villani
- Section of Digestive Diseases, Yale University, New Haven, Connecticut, USA
| | - Luca Fabris
- Department of Molecular Medicine, University of Padua, Italy
| | - Romina Fiorotto
- Section of Digestive Diseases, Yale University, New Haven, Connecticut, USA
| | - Mario Strazzabosco
- Section of Digestive Diseases, Yale University, New Haven, CT, USA; Section of Digestive Diseases, International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Milan, Italy.
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60
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Halls ML, Cooper DMF. Adenylyl cyclase signalling complexes - Pharmacological challenges and opportunities. Pharmacol Ther 2017; 172:171-180. [PMID: 28132906 DOI: 10.1016/j.pharmthera.2017.01.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Signalling pathways involving the vital second messanger, cAMP, impact on most significant physiological processes. Unsurprisingly therefore, the activation and regulation of cAMP signalling is tightly controlled within the cell by processes including phosphorylation, the scaffolding of protein signalling complexes and sub-cellular compartmentalisation. This inherent complexity, along with the highly conserved structure of the catalytic sites among the nine membrane-bound adenylyl cyclases, presents significant challenges for efficient inhibition of cAMP signalling. Here, we will describe the biochemistry and cell biology of the family of membrane-bound adenylyl cyclases, their organisation within the cell, and the nature of the cAMP signals that they produce, as a prelude to considering how cAMP signalling might be perturbed. We describe the limitations associated with direct inhibition of adenylyl cyclase activity, and evaluate alternative strategies for more specific targeting of adenylyl cyclase signalling. The inherent complexity in the activation and organisation of adenylyl cyclase activity may actually provide unique opportunities for selectively targeting discrete adenylyl cyclase functions in disease.
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Affiliation(s)
- Michelle L Halls
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Victoria, Australia
| | - Dermot M F Cooper
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK.
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61
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Pacheco J, Vaca L. STIM-TRP Pathways and Microdomain Organization: Auxiliary Proteins of the STIM/Orai Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:189-210. [DOI: 10.1007/978-3-319-57732-6_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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63
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Gueguen M, Vallin B, Glorian M, Blaise R, Limon I. [Not Available]. Biol Aujourdhui 2016; 210:153-166. [PMID: 27813476 DOI: 10.1051/jbio/2016020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Indexed: 06/06/2023]
Abstract
In response to various types of vascular stress, the smooth muscle cells of the vessel wall (VSMCs) change phenotype and acquire the capacity to react to abnormal signals. This phenomenon favors the involvement of these cells in the development of major vascular diseases, such as atherosclerosis, and some complications of angioplasty, such as restenosis. The cyclic adenosine monophosphate (cAMP) pathway plays a key role in the integration of stimuli from the immediate environment and in the development of cellular responses. The temporal and spatial subcellular compartmentalization of cAMP ensures that the signals transmitted are specific. This compartmentalization is dependent on the diversity of (1) proteins directly or indirectly regulating the synthesis, degradation or release of cAMP; (2) intracellular effectors of cAMP; (3) isoforms of all these proteins with unique biochemical properties and unique patterns of regulation and (4) the scaffolding proteins on which the macromolecular complexes are built. This review illustrates the ways in which changes in the profile of adenylyl cyclases (ACs) may play critical roles in signal integration, the response of muscle cells and pathological vascular remodeling. It also illustrates the relevance of the renewed consideration of ACs as potentially interesting treatment targets.
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64
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Okeke E, Dingsdale H, Parker T, Voronina S, Tepikin AV. Endoplasmic reticulum-plasma membrane junctions: structure, function and dynamics. J Physiol 2016; 594:2837-47. [PMID: 26939537 DOI: 10.1113/jp271142] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/13/2016] [Indexed: 12/20/2022] Open
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are contact sites between the ER and the PM; the distance between the two organelles in the junctions is below 40 nm and the membranes are connected by protein tethers. A number of molecular tools and technical approaches have been recently developed to visualise, modify and characterise properties of ER-PM junctions. The junctions serve as the platforms for lipid exchange between the organelles and for cell signalling, notably Ca(2+) and cAMP signalling. Vice versa, signalling events regulate the development and properties of the junctions. Two Ca(2+) -dependent mechanisms of de novo formation of ER-PM junctions have been recently described and characterised. The junction-forming proteins and lipids are currently the focus of vigorous investigation. Junctions can be relatively short-lived and simple structures, forming and dissolving on the time scale of a few minutes. However, complex, sophisticated and multifunctional ER-PM junctions, capable of attracting numerous protein residents and other cellular organelles, have been described in some cell types. The road from simplicity to complexity, i.e. the transformation from simple 'nascent' ER-PM junctions to advanced stable multiorganellar complexes, is likely to become an attractive research avenue for current and future junctologists. Another area of considerable research interest is the downstream cellular processes that can be activated by specific local signalling events in the ER-PM junctions. Studies of the cell physiology and indeed pathophysiology of ER-PM junctions have already produced some surprising discoveries, likely to expand with advances in our understanding of these remarkable organellar contact sites.
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Affiliation(s)
- Emmanuel Okeke
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Hayley Dingsdale
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Tony Parker
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Svetlana Voronina
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
| | - Alexei V Tepikin
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
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65
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Srivats S, Balasuriya D, Pasche M, Vistal G, Edwardson JM, Taylor CW, Murrell-Lagnado RD. Sigma1 receptors inhibit store-operated Ca2+ entry by attenuating coupling of STIM1 to Orai1. J Cell Biol 2016; 213:65-79. [PMID: 27069021 PMCID: PMC4828687 DOI: 10.1083/jcb.201506022] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 02/24/2016] [Indexed: 11/24/2022] Open
Abstract
Sigma1 receptors (σ1Rs) are expressed widely; they bind diverse ligands, including psychotropic drugs and steroids, regulate many ion channels, and are implicated in cancer and addiction. It is not known how σ1Rs exert such varied effects. We demonstrate that σ1Rs inhibit store-operated Ca(2+)entry (SOCE), a major Ca(2+)influx pathway, and reduce the Ca(2+)content of the intracellular stores. SOCE was inhibited by expression of σ1R or an agonist of σ1R and enhanced by loss of σ1R or an antagonist. Within the endoplasmic reticulum (ER), σ1R associated with STIM1, the ER Ca(2+)sensor that regulates SOCE. This interaction was modulated by σ1R ligands. After depletion of Ca(2+)stores, σ1R accompanied STIM1 to ER-plasma membrane (PM) junctions where STIM1 stimulated opening of the Ca(2+)channel, Orai1. The association of STIM1 with σ1R slowed the recruitment of STIM1 to ER-PM junctions and reduced binding of STIM1 to PM Orai1. We conclude that σ1R attenuates STIM1 coupling to Orai1 and thereby inhibits SOCE.
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Affiliation(s)
- Shyam Srivats
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK
| | - Dilshan Balasuriya
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK
| | - Mathias Pasche
- MRC Laboratory for Molecular Biology, Cambridge CB2 0QH, England, UK
| | - Gerard Vistal
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK
| | - J Michael Edwardson
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK
| | - Ruth D Murrell-Lagnado
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, England, UK Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, England, UK
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Okeke E, Parker T, Dingsdale H, Concannon M, Awais M, Voronina S, Molgó J, Begg M, Metcalf D, Knight AE, Sutton R, Haynes L, Tepikin AV. Epithelial-mesenchymal transition, IP3 receptors and ER-PM junctions: translocation of Ca2+ signalling complexes and regulation of migration. Biochem J 2016; 473:757-67. [PMID: 26759379 PMCID: PMC4785603 DOI: 10.1042/bj20150364] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 12/21/2015] [Accepted: 01/12/2016] [Indexed: 12/22/2022]
Abstract
Disconnection of a cell from its epithelial neighbours and the formation of a mesenchymal phenotype are associated with profound changes in the distribution of cellular components and the formation of new cellular polarity. We observed a dramatic redistribution of inositol trisphosphate receptors (IP3Rs) and stromal interaction molecule 1 (STIM1)-competent endoplasmic reticulum-plasma membrane junctions (ER-PM junctions) when pancreatic ductal adenocarcinoma (PDAC) cells disconnect from their neighbours and undergo individual migration. In cellular monolayers IP3Rs are juxtaposed with tight junctions. When individual cells migrate away from their neighbours IP3Rs preferentially accumulate at the leading edge where they surround focal adhesions. Uncaging of inositol trisphosphate (IP3) resulted in prominent accumulation of paxillin in focal adhesions, highlighting important functional implications of the observed novel structural relationships. ER-PM junctions and STIM1 proteins also migrate to the leading edge and position closely behind the IP3Rs, creating a stratified distribution of Ca(2+) signalling complexes in this region. Importantly, migration of PDAC cells was strongly suppressed by selective inhibition of IP3Rs and store-operated Ca(2+) entry (SOCE), indicating that these mechanisms are functionally required for migration.
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Affiliation(s)
- Emmanuel Okeke
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Tony Parker
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Hayley Dingsdale
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Matthew Concannon
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Muhammad Awais
- NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Svetlana Voronina
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Jordi Molgó
- CEA, Institut de Biologie et Technologies de Saclay (iBiTec-S), Service d'Ingénierie Moléculaire des Protéines (SIMOPRO), bâtiment 152, 91191 Gif-sur-Yvette Cedex, France Institut des Neurosciences Paris-Saclay, UMR 9197, CNRS/Université Paris-Sud, CNRS, 91190-Gif sur Yvette Cedex, France
| | - Malcolm Begg
- Respiratory Therapy Area Unit, Medicines Research Centre, GlaxoSmithKline, Stevenage SG1 2NY, England, U.K
| | - Daniel Metcalf
- Biotechnology Group, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, U.K
| | - Alex E Knight
- Biotechnology Group, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, U.K
| | - Robert Sutton
- NIHR Liverpool Pancreas Biomedical Research Unit, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Lee Haynes
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Alexei V Tepikin
- Department of Cellular and Molecular Physiology, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K.
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67
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Spinelli AM, Trebak M. Orai channel-mediated Ca2+ signals in vascular and airway smooth muscle. Am J Physiol Cell Physiol 2016; 310:C402-13. [PMID: 26718630 PMCID: PMC4796280 DOI: 10.1152/ajpcell.00355.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Orai (Orai1, Orai2, and Orai3) proteins form a family of highly Ca(2+)-selective plasma membrane channels that are regulated by stromal-interacting molecules (STIM1 and STIM2); STIM proteins are Ca(2+) sensors located in the membrane of the endoplasmic reticulum. STIM and Orai proteins are expressed in vascular and airway smooth muscle and constitute the molecular components of the ubiquitous store-operated Ca(2+) entry pathway that mediate the Ca(2+) release-activated Ca(2+) current. STIM/Orai proteins also encode store-independent Ca(2+) entry pathways in smooth muscle. Altered expression and function of STIM/Orai proteins have been linked to vascular and airway pathologies, including restenosis, hypertension, and atopic asthma. In this review we discuss our current understanding of Orai proteins and the store-dependent and -independent signaling pathways mediated by these proteins in vascular and airway smooth muscle. We also discuss the current studies linking altered expression and function of Orai proteins with smooth muscle-related pathologies.
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Affiliation(s)
- Amy M Spinelli
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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68
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Son A, Park S, Shin DM, Muallem S. Orai1 and STIM1 in ER/PM junctions: roles in pancreatic cell function and dysfunction. Am J Physiol Cell Physiol 2016; 310:C414-22. [PMID: 26739495 DOI: 10.1152/ajpcell.00349.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membrane contact sites (MCS) are critical junctions that form between the endoplasmic reticulum (ER) and membranes of various organelles, including the plasma membrane (PM). Signaling complexes, including mediators of Ca(2+) signaling, are assembled within MCS, such as the ER/PM junction. This is most evident in polarized epithelial cells, such as pancreatic cells. Core Ca(2+) signaling proteins cluster at the apical pole, the site of inositol 1,4,5-trisphosphate-mediated Ca(2+) release and Orai1/transient receptor potential canonical-mediated store-dependent Ca(2+) entry. Recent advances have characterized the proteins that tether the membranes at MCS and the role of these proteins in modulating physiological and pathological intracellular signaling. This review discusses recent advances in the characterization of Ca(2+) signaling at ER/PM junctions and the relation of these junctions to physiological and pathological Ca(2+) signaling in pancreatic acini.
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Affiliation(s)
- Aran Son
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Seonghee Park
- Department of Physiology, School of Medicine, Ewha Womans University, Seoul, Korea
| | - Dong Min Shin
- Department of Oral Biology, BK 21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland;
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69
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Gamper N. Localised intracellular signalling in neurons. J Physiol 2016; 594:7-8. [PMID: 26724480 DOI: 10.1113/jp271357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/06/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Nikita Gamper
- Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
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70
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Abstract
Store Operated Ca(2+) Entry (SOCE), the main Ca(2+) influx mechanism in non-excitable cells, is implicated in the immune response and has been reported to be affected in several pathologies including cancer. The basic molecular constituents of SOCE are Orai, the pore forming unit, and STIM, a multidomain protein with at least two principal functions: one is to sense the Ca(2+) content inside the lumen of the endoplasmic reticulum(ER) and the second is to activate Orai channels upon depletion of the ER. The link between Ca(2+) depletion inside the ER and Ca(2+) influx from extracellular media is through a direct association of STIM and Orai, but for this to occur, both molecules have to interact and form clusters where ER and plasma membrane (PM) are intimately apposed. In recent years a great number of components have been identified as participants in SOCE regulation, including regions of plasma membrane enriched in cholesterol and sphingolipids, the so called lipid rafts, which recruit a complex platform of specialized microdomains, which cells use to regulate spatiotemporal Ca(2+) signals.
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71
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Pon CK, Lane JR, Sloan EK, Halls ML. The β2-adrenoceptor activates a positive cAMP-calcium feedforward loop to drive breast cancer cell invasion. FASEB J 2015; 30:1144-54. [PMID: 26578688 DOI: 10.1096/fj.15-277798] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 11/09/2015] [Indexed: 01/04/2023]
Abstract
Activation of the sympathetic nervous system by stress increases breast cancer metastasis in vivo. Preclinical studies suggest that stress activates β-adrenoceptors (βARs) to enhance metastasis from primary tumors and that β-blockers may be protective in breast cancer. However, the subtype of βAR that mediates this effect, as well as the signaling mechanisms underlying increased tumor cell dissemination, remain unclear. We show that the β2AR is the only functionally relevant βAR subtype in the highly metastatic human breast cancer cell line MDA-MB-231HM. β2AR activation results in elevated cAMP (formoterol pEC50 9.86 ± 0.32), increased intracellular Ca(2+) (formoterol pEC50 8.20 ± 0.33) and reduced phosphorylated ERK (pERK; formoterol pIC50 11.62 ± 0.31). We demonstrate that a highly amplified positive feedforward loop between the cAMP and Ca(2+) pathways is responsible for efficient inhibition of basal pERK. Importantly, activation of the β2AR increased invasion (formoterol area under the curve [AUC] relative to vehicle: 1.82 ± 0.36), which was dependent on the cAMP/Ca(2+) loop (formoterol AUC in the presence of 2'5'-dideoxyadenosine 0.64 ± 0.03, or BAPTA-AM 0.45 ± 0.23) but independent of inhibition of basal pERK1/2 (vehicle AUC with U0126 0.60 ± 0.30). Specifically targeting the positive feedforward cAMP/Ca(2+) loop may be beneficial for the development of therapeutics to slow disease progression in patients with breast cancer.
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Affiliation(s)
- Cindy K Pon
- *Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Cousins Center, UCLA Semel Institute for Neuroscience and Human Behavior, and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, California USA; and Division of Cancer Surgery, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - J Robert Lane
- *Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Cousins Center, UCLA Semel Institute for Neuroscience and Human Behavior, and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, California USA; and Division of Cancer Surgery, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Erica K Sloan
- *Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Cousins Center, UCLA Semel Institute for Neuroscience and Human Behavior, and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, California USA; and Division of Cancer Surgery, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Michelle L Halls
- *Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; Cousins Center, UCLA Semel Institute for Neuroscience and Human Behavior, and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, California USA; and Division of Cancer Surgery, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
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72
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Nichols JM, Maiellaro I, Abi-Jaoude J, Curci S, Hofer AM. "Store-operated" cAMP signaling contributes to Ca2+-activated Cl- secretion in T84 colonic cells. Am J Physiol Gastrointest Liver Physiol 2015; 309:G670-9. [PMID: 26316590 PMCID: PMC4609931 DOI: 10.1152/ajpgi.00214.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/21/2015] [Indexed: 01/31/2023]
Abstract
Apical cAMP-dependent CFTR Cl(-) channels are essential for efficient vectorial movement of ions and fluid into the lumen of the colon. It is well known that Ca(2+)-mobilizing agonists also stimulate colonic anion secretion. However, CFTR is apparently not activated directly by Ca(2+), and the existence of apical Ca(2+)-dependent Cl(-) channels in the native colonic epithelium is controversial, leaving the identity of the Ca(2+)-activated component unresolved. We recently showed that decreasing free Ca(2+) concentration ([Ca(2+)]) within the endoplasmic reticulum (ER) lumen elicits a rise in intracellular cAMP. This process, which we termed "store-operated cAMP signaling" (SOcAMPS), requires the luminal ER Ca(2+) sensor STIM1 and does not depend on changes in cytosolic Ca(2+). Here we assessed the degree to which SOcAMPS participates in Ca(2+)-activated Cl(-) transport as measured by transepithelial short-circuit current (Isc) in polarized T84 monolayers in parallel with imaging of cAMP and PKA activity using fluorescence resonance energy transfer (FRET)-based reporters in single cells. In Ca(2+)-free conditions, the Ca(2+)-releasing agonist carbachol and Ca(2+) ionophore increased Isc, cAMP, and PKA activity. These responses persisted in cells loaded with the Ca(2+) chelator BAPTA-AM. The effect on Isc was enhanced in the presence of the phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX), inhibited by the CFTR inhibitor CFTRinh-172 and the PKA inhibitor H-89, and unaffected by Ba(2+) or flufenamic acid. We propose that a discrete component of the "Ca(2+)-dependent" secretory activity in the colon derives from cAMP generated through SOcAMPS. This alternative mode of cAMP production could contribute to the actions of diverse xenobiotic agents that disrupt ER Ca(2+) homeostasis, leading to diarrhea.
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Affiliation(s)
- Jonathan M. Nichols
- Department of Veterans Affairs Boston Healthcare System and Department of Surgery, Brigham & Women's Hospital and Harvard Medical School, West Roxbury, Massachusetts
| | - Isabella Maiellaro
- Department of Veterans Affairs Boston Healthcare System and Department of Surgery, Brigham & Women's Hospital and Harvard Medical School, West Roxbury, Massachusetts
| | - Joanne Abi-Jaoude
- Department of Veterans Affairs Boston Healthcare System and Department of Surgery, Brigham & Women's Hospital and Harvard Medical School, West Roxbury, Massachusetts
| | - Silvana Curci
- Department of Veterans Affairs Boston Healthcare System and Department of Surgery, Brigham & Women's Hospital and Harvard Medical School, West Roxbury, Massachusetts
| | - Aldebaran M. Hofer
- Department of Veterans Affairs Boston Healthcare System and Department of Surgery, Brigham & Women's Hospital and Harvard Medical School, West Roxbury, Massachusetts
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73
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Abstract
Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.
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Affiliation(s)
- Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| | - Richard S Lewis
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
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74
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Cao X, Choi S, Maléth JJ, Park S, Ahuja M, Muallem S. The ER/PM microdomain, PI(4,5)P₂ and the regulation of STIM1-Orai1 channel function. Cell Calcium 2015; 58:342-8. [PMID: 25843208 PMCID: PMC4564333 DOI: 10.1016/j.ceca.2015.03.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 03/06/2015] [Accepted: 03/09/2015] [Indexed: 12/18/2022]
Abstract
All forms of cell signaling occur in discreet cellular microdomains in which the ER is the main participant and include microdomains formed by the ER with lysosomes, endosomes, the nucleus, mitochondria and the plasma membrane. In the microdomains the two opposing organelles transfer and exchange constituents including lipids and ions. As is the case for other forms of signaling pathways, many components of the receptor-evoked Ca(2+) signal are clustered at the ER/PM microdomain, including the Orai1-STIM1 complex. This review discusses recent advances in understanding the molecular components that tether the ER and plasma membrane to form the ER/PM microdomains in which PI(4,5)P2 is enriched, and how dynamic targeting of the Orai1-STIM1 complex to PI(4,5)P2-poor and PI(4,5)P2-rich microdomains controls the activity of Orai1 and its regulation by Ca(2+) that is mediated by SARAF.
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Affiliation(s)
- Xu Cao
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, United States
| | - Seok Choi
- Department of Physiology, College of Medicine, Chosun University, 501-375, Republic of Korea
| | - Jozsef J Maléth
- First Department of Medicine, University of Szeged, Szeged H-6725, Hungary
| | - Seonghee Park
- Department of Physiology, School of Medicine, Ewha Womans University, 911-1 Mok-6-dong, Yang Chun-gu, Seoul 158-710, Republic of Korea
| | - Malini Ahuja
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, United States
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
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75
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Pinto MCX, Kihara AH, Goulart VAM, Tonelli FMP, Gomes KN, Ulrich H, Resende RR. Calcium signaling and cell proliferation. Cell Signal 2015; 27:2139-49. [PMID: 26275497 DOI: 10.1016/j.cellsig.2015.08.006] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/04/2015] [Accepted: 08/10/2015] [Indexed: 12/17/2022]
Abstract
Cell proliferation is orchestrated through diverse proteins related to calcium (Ca(2+)) signaling inside the cell. Cellular Ca(2+) influx that occurs first by various mechanisms at the plasma membrane, is then followed by absorption of Ca(2+) ions by mitochondria and endoplasmic reticulum, and, finally, there is a connection of calcium stores to the nucleus. Experimental evidence indicates that the fluctuation of Ca(2+) from the endoplasmic reticulum provides a pivotal and physiological role for cell proliferation. Ca(2+) depletion in the endoplasmatic reticulum triggers Ca(2+) influx across the plasma membrane in an phenomenon called store-operated calcium entries (SOCEs). SOCE is activated through a complex interplay between a Ca(2+) sensor, denominated STIM, localized in the endoplasmic reticulum and a Ca(2+) channel at the cell membrane, denominated Orai. The interplay between STIM and Orai proteins with cell membrane receptors and their role in cell proliferation is discussed in this review.
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Affiliation(s)
- Mauro Cunha Xavier Pinto
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Univtreersidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Presyes 748, 05508-000 São Paulo, SP, Brazil; Instituto Nanocell, Rua Santo Antônio, 420, 35500-041 Divinópolis, MG, Brazil
| | - Alexandre Hiroaki Kihara
- Universidade Federal do ABC, Centro de Matemática, Computação e Cognição, Rua Arcturus (Jd Antares), 09606-070, São Bernardo do Campo, SP, Brazil
| | - Vânia A M Goulart
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Univtreersidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil; Instituto Nanocell, Rua Santo Antônio, 420, 35500-041 Divinópolis, MG, Brazil
| | - Fernanda M P Tonelli
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Univtreersidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil; Instituto Nanocell, Rua Santo Antônio, 420, 35500-041 Divinópolis, MG, Brazil
| | - Katia N Gomes
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Univtreersidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Presyes 748, 05508-000 São Paulo, SP, Brazil
| | - Rodrigo R Resende
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Univtreersidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil; Instituto Nanocell, Rua Santo Antônio, 420, 35500-041 Divinópolis, MG, Brazil.
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76
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Patel N, Gold MG. The genetically encoded tool set for investigating cAMP: more than the sum of its parts. Front Pharmacol 2015; 6:164. [PMID: 26300778 PMCID: PMC4526808 DOI: 10.3389/fphar.2015.00164] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/24/2015] [Indexed: 11/13/2022] Open
Abstract
Intracellular fluctuations of the second messenger cyclic AMP (cAMP) are regulated with spatial and temporal precision. This regulation is supported by the sophisticated arrangement of cyclases, phosphodiesterases, anchoring proteins, and receptors for cAMP. Discovery of these nuances to cAMP signaling has been facilitated by the development of genetically encodable tools for monitoring and manipulating cAMP and the proteins that support cAMP signaling. In this review, we discuss the state-of-the-art in development of different genetically encoded tools for sensing cAMP and the activity of its primary intracellular receptor protein kinase A (PKA). We introduce sequences for encoding adenylyl cyclases that enable cAMP levels to be artificially elevated within cells. We chart the evolution of sequences for selectively modifying protein-protein interactions that support cAMP signaling, and for driving cAMP sensors and manipulators to different subcellular locations. Importantly, these different genetically encoded tools can be applied synergistically, and we highlight notable instances that take advantage of this property. Finally, we consider prospects for extending the utility of the tool set to support further insights into the role of cAMP in health and disease.
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Affiliation(s)
- Neha Patel
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
| | - Matthew G Gold
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
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77
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Desai PN, Zhang X, Wu S, Janoshazi A, Bolimuntha S, Putney JW, Trebak M. Multiple types of calcium channels arising from alternative translation initiation of the Orai1 message. Sci Signal 2015; 8:ra74. [PMID: 26221052 PMCID: PMC4583604 DOI: 10.1126/scisignal.aaa8323] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In mammals exclusively, the pore-forming Ca(2+) release-activated Ca(2+) (CRAC) channel subunit Orai1 occurs in two forms because of alternative translation initiation. The longer, mammal-specific Orai1α contains an additional 63 amino acids upstream of the conserved start site for Orai1β, which occurs at methionine 64 in Orai1α. Orai1 participates in the generation of three distinct Ca(2+) currents, including two store-operated currents: Icrac, which involves activation of Orai1 channels by the Ca(2+)-sensing protein STIM1 (stromal interaction molecule 1), and Isoc, which involves an interaction among Orai1, the transient receptor potential (TRP) family member TRPC1 (TRP canonical 1), and STIM1. Orai1 is also a pore-forming subunit of an arachidonic acid (or leukotriene C4)-regulated current Iarc that involves interactions among Orai1, Orai3, and STIM1. We evaluated the roles of the two Orai1 forms in the Ca(2+) currents Icrac, Isoc, and Iarc. We found that Orai1α and Orai1β were largely interchangeable for Icrac and Isoc, although Orai1α exhibited stronger inhibition by Ca(2+). Only the mammalian-specific Orai1α functioned in the arachidonic acid-regulated current Iarc. Thus, alternative translation initiation of the Orai1 message produces at least three types of Ca(2+) channels with distinct signaling and regulatory properties.
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Affiliation(s)
- Pooja N Desai
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Shilan Wu
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Agnes Janoshazi
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Sunitha Bolimuntha
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - James W Putney
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA.
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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78
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Abstract
Adrenergic signaling, in particular signaling in the sympathetic nervous system, is a prime example of the control of an essential physiological system. It has served as a model system both for the control of mediator release and for receptor signaling and regulation. This review covers the historical development of the field and then addresses issues that represent key fields of ongoing research: the mechanisms and kinetics of receptor activation, temporal patterns of downstream signaling and signal bias, receptor mobility and aggregation, and signal compartmentation and specificity. The available evidence suggests that adrenergic signaling may involve complex spatiotemporal patterns, which give texture to the signaling process and may contain additional biological information.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
- Rudolf Virchow Center, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
- Comprehensive Heart Failure Center, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
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79
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Abstract
The regulatory protein STIM1 controls gating of the Ca(2+) channel ORAI1 by a direct protein-protein interaction. Because STIM1 is anchored in the ER membrane and ORAI1 is in the plasma membrane, the STIM-ORAI pathway can support Ca(2+) influx only where the two membranes come into close apposition, effectively demarcating a microdomain for Ca(2+) signalling. This review begins with a brief summary of the STIM-ORAI pathway of store-operated Ca(2+) influx, then turns to the special geometry of the STIM-ORAI microdomain and the expected characteristics of the microdomain Ca(2+) signal. A final section of the review seeks to place the STIM-ORAI microdomain into a broader context of cellular Ca(2+) signalling.
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Affiliation(s)
- Patrick G Hogan
- La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA.
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80
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Neurochondrin is an atypical RIIα-specific A-kinase anchoring protein. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1667-75. [PMID: 25916936 DOI: 10.1016/j.bbapap.2015.04.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 12/25/2022]
Abstract
Protein kinase activity is regulated not only by direct strategies affecting activity but also by spatial and temporal regulatory mechanisms. Kinase signaling pathways are coordinated by scaffolding proteins that orchestrate the assembly of multi-protein complexes. One family of such scaffolding proteins are the A-kinase anchoring proteins (AKAPs). AKAPs share the commonality of binding cAMP-dependent protein kinase (PKA). In addition, they bind further signaling proteins and kinase substrates and tether such multi-protein complexes to subcellular locations. The A-kinase binding (AKB) domain of AKAPs typically contains a conserved helical motif that interacts directly with the dimerization/docking (D/D) domain of the regulatory subunits of PKA. Based on a pull-down proteomics approach, we identified neurochondrin (neurite-outgrowth promoting protein) as a previously unidentified AKAP. Here, we show that neurochondrin interacts directly with PKA through a novel mechanism that involves two distinct binding regions. In addition, we demonstrate that neurochondrin has strong isoform selectivity towards the RIIα subunit of PKA with nanomolar affinity. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases.
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81
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Cooper DMF. Store-operated Ca²⁺-entry and adenylyl cyclase. Cell Calcium 2015; 58:368-75. [PMID: 25978874 DOI: 10.1016/j.ceca.2015.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 02/06/2023]
Abstract
One of the longest-standing effects of SOCE is in its selective regulation of Ca(2+)-sensitive adenylyl cyclase (AC) activity in non-excitable cells. Remarkably it was this source of Ca(2+) (SOCE) rather than the apparent magnitude of the Ca(2+)-rise that conferred AC responsiveness. The molecular basis for this dependence is now resolved in the case of adenylyl cyclase 8 (AC8). Sensors for Ca(2+) and cAMP targeted to ACs have been particularly useful in dissecting the influences upon and composition of what turn out to be signalling microdomains centred on ACs. A number of physiological processes depend on the regulation by SOCE of ACs, but the issue is under-studied. Here I will expand on these topics and point to some immediate unresolved questions.
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Affiliation(s)
- Dermot M F Cooper
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom.
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82
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Raoux M, Vacher P, Papin J, Picard A, Kostrzewa E, Devin A, Gaitan J, Limon I, Kas MJ, Magnan C, Lang J. Multilevel control of glucose homeostasis by adenylyl cyclase 8. Diabetologia 2015; 58:749-57. [PMID: 25403481 DOI: 10.1007/s00125-014-3445-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/28/2014] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS Nutrient homeostasis requires integration of signals generated by glucose metabolism and hormones. Expression of the calcium-stimulated adenylyl cyclase ADCY8 is regulated by glucose and the enzyme is capable of integrating signals from multiple pathways. It may thus have an important role in glucose-induced signalling and glucose homeostasis. METHODS We used pharmacological and genetic approaches in beta cells to determine secretion and calcium metabolism. Furthermore, Adcy8 knockout mice were characterised. RESULTS In clonal beta cells, inhibitors of adenylyl cyclases or their downstream targets reduced the glucose-induced increase in cytosolic calcium and insulin secretion. This was reproduced by knock-down of ADCY8, but not of ADCY1. These agents also inhibited glucose-induced increase in cytosolic calcium and electrical activity in primary beta cells and similar effects were observed after ADCY8 knock-down. Moreover, insulin secretion was diminished in islets from Adcy8 knockout mice. These mice were glucose intolerant after oral or intraperitoneal administration of glucose whereas their levels of glucagon-like peptide-1 remained unaltered. Finally, we knocked down ADCY8 in the ventromedial hypothalamus to evaluate the need for ADCY8 in the central regulation of glucose homeostasis. Whereas mice fed a standard diet had normal glucose levels, high-fat diet exacerbated glucose intolerance and knock-down mice were incapable of raising their plasma insulin levels. Finally we confirmed that ADCY8 is expressed in human islets. CONCLUSIONS/INTERPRETATIONS Collectively, our findings demonstrate that ADCY8 is required for the physiological activation of glucose-induced signalling pathways in beta cells, for glucose tolerance and for hypothalamic adaptation to a high-fat diet via regulation of islet insulin secretion.
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Affiliation(s)
- Matthieu Raoux
- Université de Bordeaux, CNRS UMR 5248, Chimie et Biologie des Membranes et Nano-objets, Batiment B14, Allée Geoffrey St Hilaire, CS90063, F-33615, Pessac, France
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83
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Abstract
SOCE (store-operated Ca2+ entry) is mediated via specific plasma membrane channels in response to ER (endoplasmic reticulum) Ca2+ store depletion. This route of Ca2+ entry is central to the dynamic interplay between Ca2+ and cAMP signalling in regulating the activity of Ca2+-sensitive adenylate cyclase isoforms (AC1, AC5, AC6 and AC8). Two proteins have been identified as key components of SOCE: STIM1 (stromal interaction molecule 1), which senses ER Ca2+ store content and translocates to the plasma membrane upon store depletion, where it then activates Orai1, the pore-forming component of the CRAC (Ca2+ release-activated Ca2+) channel. Previous studies reported that co-expression of STIM1 and Orai1 in HEK-293 (human embryonic kidney 293) cells enhances Ca2+-stimulated AC8 activity and that AC8 and Orai1 directly interact to enhance this regulation. Nonetheless, the additional involvement of TRPC (transient receptor potential canonical) channels in SOCE has also been proposed. In the present study, we evaluate the contribution of TRPC1 to SOCE-mediated regulation of Ca2+-sensitive ACs in HEK-293 cells stably expressing AC8 (HEK-AC8) and HSG (human submandibular gland) cells expressing an endogenous Ca2+-inhibited AC6. We demonstrate a role for TRPC1 as an integral component of SOCE, alongside STIM1 and Orai1, in regulating Ca2+ fluxes within AC microdomains and influencing cAMP production.
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84
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Ong HL, de Souza LB, Zheng C, Cheng KT, Liu X, Goldsmith CM, Feske S, Ambudkar IS. STIM2 enhances receptor-stimulated Ca²⁺ signaling by promoting recruitment of STIM1 to the endoplasmic reticulum-plasma membrane junctions. Sci Signal 2015; 8:ra3. [PMID: 25587190 DOI: 10.1126/scisignal.2005748] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A central component of receptor-evoked Ca(2+) signaling is store-operated Ca(2+) entry (SOCE), which is activated by the assembly of STIM1-Orai1 channels in endoplasmic reticulum (ER) and plasma membrane (PM) (ER-PM) junctions in response to depletion of ER Ca(2+). We report that STIM2 enhances agonist-mediated activation of SOCE by promoting STIM1 clustering in ER-PM junctions at low stimulus intensities. Targeted deletion of STIM2 in mouse salivary glands diminished fluid secretion in vivo and SOCE activation in dispersed salivary acinar cells stimulated with low concentrations of muscarinic receptor agonists. STIM2 knockdown in human embryonic kidney (HEK) 293 cells diminished agonist-induced Ca(2+) signaling and nuclear translocation of NFAT (nuclear factor of activated T cells). STIM2 lacking five carboxyl-terminal amino acid residues did not promote formation of STIM1 puncta at low concentrations of agonist, whereas coexpression of STIM2 with STIM1 mutant lacking the polybasic region STIM1ΔK resulted in co-clustering of both proteins. Together, our findings suggest that STIM2 recruits STIM1 to ER-PM junctions at low stimulus intensities when ER Ca(2+) stores are mildly depleted, thus increasing the sensitivity of Ca(2+) signaling to agonists.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Lorena Brito de Souza
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Changyu Zheng
- Translational Research Core, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, USA
| | - Kwong Tai Cheng
- Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Xibao Liu
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Corinne M Goldsmith
- Translational Research Core, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, USA
| | - Stefan Feske
- Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Indu S Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA.
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85
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Averaimo S, Nicol X. Intermingled cAMP, cGMP and calcium spatiotemporal dynamics in developing neuronal circuits. Front Cell Neurosci 2014; 8:376. [PMID: 25431549 PMCID: PMC4230202 DOI: 10.3389/fncel.2014.00376] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/21/2014] [Indexed: 01/27/2023] Open
Abstract
cAMP critically modulates the development of neuronal connectivity. It is involved in a wide range of cellular processes that require independent regulation. However, our understanding of how this single second messenger achieves specific modulation of the signaling pathways involved remains incomplete. The subcellular compartmentalization and temporal regulation of cAMP signals have recently been identified as important coding strategies leading to specificity. Dynamic interactions of this cyclic nucleotide with other second messenger including calcium and cGMP are critically involved in the regulation of spatiotemporal control of cAMP. Recent technical improvements of fluorescent sensors facilitate cAMP monitoring, whereas optogenetic tools permit spatial and temporal control of cAMP manipulations, all of which enabled the direct investigation of spatiotemporal characteristics of cAMP modulation in developing neurons. Focusing on neuronal polarization, neurotransmitter specification, axon guidance, and refinement of neuronal connectivity, we summarize herein the recent advances in understanding the features of cAMP signals and their dynamic interactions with calcium and cGMP involved in shaping the nervous system.
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Affiliation(s)
- Stefania Averaimo
- UMR_7210, Centre National de la Recherche Scientifique Paris, France ; UMR_S 968, Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06 Paris, France ; U968, Institut National de la Santé et de la Recherche Médicale Paris, France
| | - Xavier Nicol
- UMR_7210, Centre National de la Recherche Scientifique Paris, France ; UMR_S 968, Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06 Paris, France ; U968, Institut National de la Santé et de la Recherche Médicale Paris, France
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86
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Abstract
Recent advances in the AC (adenylate cyclase)/cAMP field reveal overarching roles for the ACs. Whereas few processes are unaffected by cAMP in eukaryotes, ranging from the rapid modulation of ion channel kinetics to the slowest developmental effects, the large number of cellular processes modulated by only three intermediaries, i.e. PKA (protein kinase A), Epacs (exchange proteins directly activated by cAMP) and CNG (cyclic nucleotide-gated) channels, poses the question of how selectivity and fine control is achieved by cAMP. One answer rests on the number of differently regulated and distinctly expressed AC species. Specific ACs are implicated in processes such as insulin secretion, immunological responses, sino-atrial node pulsatility and memory formation, and specific ACs are linked with particular diseased conditions or predispositions, such as cystic fibrosis, Type 2 diabetes and dysrhythmias. However, much of the selectivity and control exerted by cAMP lies in the sophisticated properties of individual ACs, in terms of their coincident responsiveness, dynamic protein scaffolding and organization of cellular microassemblies. The ACs appear to be the centre of highly organized microdomains, where both cAMP and Ca2+, the other major influence on ACs, change in patterns quite discrete from the broad cellular milieu. How these microdomains are organized is beginning to become clear, so that ACs may now be viewed as fundamental signalling centres, whose properties exceed their production of cAMP. In the present review, we summarize how ACs are multiply regulated and the steps that are put in place to ensure discrimination in their signalling. This includes scaffolding of targets and modulators by the ACs and assembling of signalling nexuses in discrete cellular domains. We also stress how these assemblies are cell-specific, context-specific and dynamic, and may be best addressed by targeted biosensors. These perspectives on the organization of ACs uncover new strategies for intervention in systems mediated by cAMP, which promise far more informed specificity than traditional approaches.
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87
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Lefkimmiatis K, Zaccolo M. cAMP signaling in subcellular compartments. Pharmacol Ther 2014; 143:295-304. [PMID: 24704321 PMCID: PMC4117810 DOI: 10.1016/j.pharmthera.2014.03.008] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 01/11/2023]
Abstract
In the complex microcosm of a cell, information security and its faithful transmission are critical for maintaining internal stability. To achieve a coordinated response of all its parts to any stimulus the cell must protect the information received from potentially confounding signals. Physical segregation of the information transmission chain ensures that only the entities able to perform the encoded task have access to the relevant information. The cAMP intracellular signaling pathway is an important system for signal transmission responsible for the ancestral 'flight or fight' response and involved in the control of critical functions including frequency and strength of heart contraction, energy metabolism and gene transcription. It is becoming increasingly apparent that the cAMP signaling pathway uses compartmentalization as a strategy for coordinating the large number of key cellular functions under its control. Spatial confinement allows the formation of cAMP signaling "hot spots" at discrete subcellular domains in response to specific stimuli, bringing the information in proximity to the relevant effectors and their recipients, thus achieving specificity of action. In this report we discuss how the different constituents of the cAMP pathway are targeted and participate in the formation of cAMP compartmentalized signaling events. We illustrate a few examples of localized cAMP signaling, with a particular focus on the nucleus, the sarcoplasmic reticulum and the mitochondria. Finally, we discuss the therapeutic potential of interventions designed to perturb specific cAMP cascades locally.
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Affiliation(s)
| | - Manuela Zaccolo
- Department Of Physiology, Anatomy & Genetics, University of Oxford, UK.
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88
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Wu MM, Covington ED, Lewis RS. Single-molecule analysis of diffusion and trapping of STIM1 and Orai1 at endoplasmic reticulum-plasma membrane junctions. Mol Biol Cell 2014; 25:3672-85. [PMID: 25057023 PMCID: PMC4230625 DOI: 10.1091/mbc.e14-06-1107] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
STIM1 and Orai1 move to endoplasmic reticulum–plasma membrane (ER-PM) junctions to trigger store-operated Ca2+ entry. Single-molecule tracking reveals pure diffusion of STIM1 in the ER, subdiffusion of Orai1 in the PM, and trapping at junctions via STIM-Orai binding. STIM-Orai binding is loose, generating free proteins that can exchange freely with extrajunctional pools. Following endoplasmic reticulum (ER) Ca2+ depletion, STIM1 and Orai1 complexes assemble autonomously at ER–plasma membrane (PM) junctions to trigger store-operated Ca2+ influx. One hypothesis to explain this process is a diffusion trap in which activated STIM1 diffusing in the ER becomes trapped at junctions through interactions with the PM, and STIM1 then traps Orai1 in the PM through binding of its calcium release-activated calcium activation domain. We tested this model by analyzing STIM1 and Orai1 diffusion using single-particle tracking, photoactivation of protein ensembles, and Monte Carlo simulations. In resting cells, STIM1 diffusion is Brownian, while Orai1 is slightly subdiffusive. After store depletion, both proteins slow to the same speeds, consistent with complex formation, and are confined to a corral similar in size to ER–PM junctions. While the escape probability at high STIM:Orai expression ratios is <1%, it is significantly increased by reducing the affinity of STIM1 for Orai1 or by expressing the two proteins at comparable levels. Our results provide direct evidence that STIM-Orai complexes are trapped by their physical connections across the junctional gap, but also reveal that the complexes are surprisingly dynamic, suggesting that readily reversible binding reactions generate free STIM1 and Orai1, which engage in constant diffusional exchange with extrajunctional pools.
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Affiliation(s)
- Minnie M Wu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Elizabeth D Covington
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Richard S Lewis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
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89
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Kar P, Samanta K, Kramer H, Morris O, Bakowski D, Parekh AB. Dynamic assembly of a membrane signaling complex enables selective activation of NFAT by Orai1. Curr Biol 2014; 24:1361-1368. [PMID: 24909327 PMCID: PMC4062936 DOI: 10.1016/j.cub.2014.04.046] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 12/12/2022]
Abstract
NFAT-dependent gene expression is essential for the development and function of the nervous, immune, and cardiovascular systems and kidney, bone, and skeletal muscle [1]. Most NFAT protein resides in the cytoplasm because of extensive phosphorylation, which masks a nuclear localization sequence. Dephosphorylation by the Ca2+-calmodulin-activated protein phosphatase calcineurin triggers NFAT migration into the nucleus [2, 3]. In some cell types, NFAT can be activated by Ca2+ nanodomains near open store-operated Orai1 and voltage-gated Ca2+ channels in the plasma membrane [4, 5]. How local Ca2+ near Orai1 is detected and whether other Orai channels utilize a similar mechanism remain unclear. Here, we report that the paralog Orai3 fails to activate NFAT. Orai1 is effective in activating gene expression via Ca2+ nanodomains because it participates in a membrane-delimited signaling complex that forms after store depletion and brings calcineurin, via the scaffolding protein AKAP79, to calmodulin tethered to Orai1. By contrast, Orai3 interacts less well with AKAP79 after store depletion, rendering it ineffective in activating NFAT. A channel chimera of Orai3 with the N terminus of Orai1 was able to couple local Ca2+ entry to NFAT activation, identifying the N-terminal domain of Orai1 as central to Ca2+ nanodomain-transcription coupling. The formation of a store-dependent signaling complex at the plasma membrane provides for selective activation of a fundamental downstream response by Orai1. Ca2+ store depletion leads to the formation of a plasmalemmal signaling complex AKAP79, with bound calcineurin and NFAT1, couples to the N terminus of Orai1 channels Ca2+ entry though the channels releases activated NFAT, leading to gene expression These results identify a mechanism for selective activation of a response by Orai1
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Affiliation(s)
- Pulak Kar
- Department of Physiology, Anatomy, and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, UK
| | - Krishna Samanta
- Department of Physiology, Anatomy, and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, UK
| | - Holger Kramer
- Department of Physiology, Anatomy, and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, UK
| | - Otto Morris
- Department of Physiology, Anatomy, and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, UK
| | - Daniel Bakowski
- Department of Physiology, Anatomy, and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, UK
| | - Anant B Parekh
- Department of Physiology, Anatomy, and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, UK.
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90
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Mid-range Ca2+ signalling mediated by functional coupling between store-operated Ca2+ entry and IP3-dependent Ca2+ release. Nat Commun 2014; 5:3916. [PMID: 24867608 DOI: 10.1038/ncomms4916] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/17/2014] [Indexed: 11/08/2022] Open
Abstract
The versatility and universality of Ca(2+) signals stem from the breadth of their spatial and temporal dynamics. Spatially, Ca(2+) signalling is well studied in the microdomain scale, close to a Ca(2+) channel, and at the whole-cell level. However, little is known about how local Ca(2+) signals are regulated to specifically activate spatially distant effectors without a global Ca(2+) rise. Here we show that an intricate coupling between the inositol 1,4,5 trisphosphate (IP3) receptor, SERCA pump and store-operated Ca(2+) entry (SOCE) allows for efficient mid-range Ca(2+) signalling. Ca(2+) flowing through SOCE is taken up into the ER lumen by the SERCA pump, only to be re-released by IP3Rs to activate distal Ca(2+)-activated Cl(-) channels (CaCCs). This CaCC regulation contributes to setting the membrane potential of the cell. Hence functional coupling between SOCE, SERCA and IP3R limits local Ca(2+) diffusion and funnels Ca(2+) through the ER lumen to activate a spatially separate Ca(2+) effector.
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91
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Srikanth S, Gwack Y. Molecular regulation of the pore component of CRAC channels, Orai1. CURRENT TOPICS IN MEMBRANES 2014; 71:181-207. [PMID: 23890116 DOI: 10.1016/b978-0-12-407870-3.00008-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Store-operated Ca(2+) entry (SOCE) is a fundamental mechanism ubiquitously employed by cells to elevate intracellular Ca(2+) concentrations ([Ca(2+)]i). Increased intracellular Ca(2+) ions act as a second messenger that can stimulate a variety of downstream signaling pathways affecting proliferation, secretion, differentiation, and death of cells. In immune cells, immune receptor stimulation induces endoplasmic reticulum Ca(2+) store depletion that subsequently activates Ca(2+)-release-activated-Ca(2+) (CRAC) channels, a prototype of store-operated Ca(2+) (SOC) channels. Identification of Orai1 as the pore subunit of CRAC channels has provided the much-needed molecular tool to dissect the mechanism of activation and regulation of these channels. In this review, we discuss the recent advances in understanding the regulatory mechanisms and posttranslational modifications that regulate diverse aspects of CRAC channel function.
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Affiliation(s)
- Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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92
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Sabbatini ME, Gorelick F, Glaser S. Adenylyl cyclases in the digestive system. Cell Signal 2014; 26:1173-81. [PMID: 24521753 DOI: 10.1016/j.cellsig.2014.01.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 01/31/2014] [Indexed: 02/08/2023]
Abstract
Adenylyl cyclases (ACs) are a group of widely distributed enzymes whose functions are very diverse. There are nine known transmembrane AC isoforms activated by Gαs. Each has its own pattern of expression in the digestive system and differential regulation of function by Ca(2+) and other intracellular signals. In addition to the transmembrane isoforms, one AC is soluble and exhibits distinct regulation. In this review, the basic structure, regulation and physiological roles of ACs in the digestive system are discussed.
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Affiliation(s)
| | - Fred Gorelick
- Department of Cell Biology and Medicine, Yale University, United States; VA CT, United States
| | - Shannon Glaser
- Department of Internal Medicine, Scott & White-Digestive Disease Research Center, Texas A&M Health Science Center, Central Texas Veterans Health Care System, United States
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93
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cAMP and Ca²⁺ signaling in secretory epithelia: crosstalk and synergism. Cell Calcium 2014; 55:385-93. [PMID: 24613710 DOI: 10.1016/j.ceca.2014.01.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 01/29/2014] [Accepted: 01/30/2014] [Indexed: 12/15/2022]
Abstract
The Ca(2+) and cAMP/PKA pathways are the primary signaling systems in secretory epithelia that control virtually all secretory gland functions. Interaction and crosstalk in Ca(2+) and cAMP signaling occur at multiple levels to control and tune the activity of each other. Physiologically, Ca(2+) and cAMP signaling operate at 5-10% of maximal strength, but synergize to generate the maximal response. Although synergistic action of the Ca(2+) and cAMP signaling is the common mode of signaling and has been known for many years, we know very little of the molecular mechanism and mediators of the synergism. In this review, we discuss crosstalk between the Ca(2+) and cAMP signaling and the function of IRBIT (IP3 receptors binding protein release with IP3) as a third messenger that mediates the synergistic action of the Ca(2+) and cAMP signaling.
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94
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Müller MS, Fox R, Schousboe A, Waagepetersen HS, Bak LK. Astrocyte glycogenolysis is triggered by store-operated calcium entry and provides metabolic energy for cellular calcium homeostasis. Glia 2014; 62:526-34. [PMID: 24464850 DOI: 10.1002/glia.22623] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/11/2013] [Accepted: 12/16/2013] [Indexed: 01/14/2023]
Abstract
Astrocytic glycogen, the only storage form of glucose in the brain, has been shown to play a fundamental role in supporting learning and memory, an effect achieved by providing metabolic support for neurons. We have examined the interplay between glycogenolysis and the bioenergetics of astrocytic Ca(2+) homeostasis, by analyzing interdependency of glycogen and store-operated Ca(2+) entry (SOCE), a mechanism in cellular signaling that maintains high endoplasmatic reticulum (ER) Ca(2+) concentration and thus provides the basis for store-dependent Ca(2+) signaling. We stimulated SOCE in primary cultures of murine cerebellar and cortical astrocytes, and determined glycogen content to investigate the effects of SOCE on glycogen metabolism. By blocking glycogenolysis, we tested energetic dependency of SOCE-related Ca(2+) dynamics on glycogenolytic ATP. Our results show that SOCE triggers astrocytic glycogenolysis. Upon inhibition of adenylate cyclase with 2',5'-dideoxyadenosine, glycogen content was no longer significantly different from that in unstimulated control cells, indicating that SOCE triggers astrocytic glycogenolysis in a cAMP-dependent manner. When glycogenolysis was inhibited in cortical astrocytes by 1,4-dideoxy-1,4-imino-D-arabinitol, the amount of Ca(2+) loaded into ER via sarco/endoplasmic reticulum Ca(2)-ATPase (SERCA) was reduced, which suggests that SERCA pumps preferentially metabolize glycogenolytic ATP. Our study demonstrates SOCE as a novel pathway in stimulating astrocytic glycogenolysis. We also provide first evidence for a new functional role of brain glycogen, in providing local ATP to SERCA, thus establishing the bioenergetic basis for astrocytic Ca(2+) signaling. This mechanism could offer a novel explanation for the impact of glycogen on learning and memory.
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Affiliation(s)
- Margit S Müller
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100, Copenhagen, Denmark
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95
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Lee KL, Hoey DA, Spasic M, Tang T, Hammond HK, Jacobs CR. Adenylyl cyclase 6 mediates loading-induced bone adaptation in vivo. FASEB J 2013; 28:1157-65. [PMID: 24277577 DOI: 10.1096/fj.13-240432] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Primary cilia are single, nonmotile, antenna-like structures extending from the apical membrane of most mammalian cells. They may mediate mechanotransduction, the conversion of external mechanical stimuli into biochemical intracellular signals. Previously we demonstrated that adenylyl cyclase 6 (AC6), a membrane-bound enzyme enriched in primary cilia of MLO-Y4 osteocyte-like cells, may play a role in a primary cilium-dependent mechanism of osteocyte mechanotransduction in vitro. In this study, we determined whether AC6 deletion impairs loading-induced bone formation in vivo. Skeletally mature mice with a global knockout of AC6 exhibited normal bone morphology and responded to osteogenic chemical stimuli similar to wild-type mice. Following ulnar loading over 3 consecutive days, bone formation parameters were assessed using dynamic histomorphometry. Mice lacking AC6 formed significantly less bone than control animals (41% lower bone formation rate). Furthermore, there was an attenuated flow-induced increase in COX-2 mRNA expression levels in primary bone cells isolated from AC6 knockout mice compared to controls (1.3±0.1- vs. 2.6±0.2-fold increase). Collectively, these data indicate that AC6 plays a role in loading-induced bone adaptation, and these findings are consistent with our previous studies implicating primary cilia and AC6 in a novel mechanism of osteocyte mechanotransduction.
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Affiliation(s)
- Kristen L Lee
- 1Columbia University, 351 Engineering Terr., 1210 Amsterdam Ave., Mail Code 8904, New York, NY 10027, USA.
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96
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An improved targeted cAMP sensor to study the regulation of adenylyl cyclase 8 by Ca2+ entry through voltage-gated channels. PLoS One 2013; 8:e75942. [PMID: 24086669 PMCID: PMC3781085 DOI: 10.1371/journal.pone.0075942] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/19/2013] [Indexed: 11/19/2022] Open
Abstract
Here we describe an improved sensor with reduced pH sensitivity tethered to adenylyl cyclase (AC) 8. The sensor was used to study cAMP dynamics in the AC8 microdomain of MIN6 cells, a pancreatic β-cell line. In these cells, AC8 was activated by Ca(2+) entry through L-type voltage-gated channels following depolarisation. This activation could be reconstituted in HEK293 cells co-expressing AC8 and either the α1C or α1D subunit of L-type voltage-gated Ca(2+) channels. The development of this improved sensor opens the door to the study of cAMP microdomains in excitable cells that have previously been challenging due to the sensitivity of fluorescent proteins to pH changes.
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97
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A relay mechanism between EB1 and APC facilitate STIM1 puncta assembly at endoplasmic reticulum-plasma membrane junctions. Cell Calcium 2013; 54:246-56. [PMID: 23871111 DOI: 10.1016/j.ceca.2013.06.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/19/2013] [Accepted: 06/21/2013] [Indexed: 12/20/2022]
Abstract
The assembly of STIM1 protein puncta near endoplasmic reticulum-plasma membrane (ER-PM) junctions is required for optimal activation of store-operated channels (SOC). The mechanisms controlling the translocation of STIM1 puncta to ER-PM junctions remain largely unknown. In the present study, we have explored the role of the microtubule binding protein adenomatous polyposis coli (APC), on STIM1 puncta and store-operated calcium entry (SOCE). APC-depleted cells showed reduced STIM1 puncta near ER-PM junctions, instead puncta is found at the ER surrounding the cell nucleus. Reduced STIM1 puncta near ER-PM junctions in APC-depleted cells correlates with a strong inhibition of SOCE and diminished Orai whole-cell currents. Immunoprecipitation and confocal microscopy co-localization studies indicate that, upon depletion of the ER, STIM1 dissociates from EB1 and associates to APC. Deletion analysis identified an APC-binding domain in the carboxyl terminus of STIM1 (STIM1 650-685). These results together position APC as an important element in facilitating the translocation of STIM1 puncta near ER-PM junctions, which in turn is required for efficient SOCE and Orai activation upon depletion of the ER.
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98
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Abstract
Cytoplasmic Ca(2+) is an universal intracellular messenger that activates cellular responses over a broad temporal range, from neurotransmitter release to cell growth and proliferation. Inherent to the use of the multifarious Ca(2+) signal is the question of specificity: how can some Ca(2+)-dependent responses be activated in a cell and not others? A rise in cytoplasmic Ca(2+) can evoke a response either by binding directly to the target (as occurs with certain Ca(2+)-activated K(+) and Cl(-) channels, for example) or through recruitment of intermediary proteins, such as calmodulin and troponin C. A substantial body of evidence has now established that Ca(2+)-binding proteins differ both in their affinities for Ca(2+) and in their on- and off-rates for Ca(2+) binding/unbinding. Furthermore, different Ca(2+)-binding proteins often occupy distinct locations within the cell. Therefore, the size, kinetics and spatial profile of a cytoplasmic Ca(2+) signal are all important in determining which Ca(2+)-dependent response will be activated, when and for how long.
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Affiliation(s)
- Pulak Kar
- Department of Physiology, Anatomy and Genetics; University of Oxford; Oxford, UK
| | - Anant Parekh
- Department of Physiology, Anatomy and Genetics; University of Oxford; Oxford, UK
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99
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Abstract
We demonstrated three novel forms of dynamic behaviour of junctions between the ER (endoplasmic reticulum) and the PM (plasma membrane) in migrating cancer cells: saltatory formation, long-distance sliding and dissolution. The individual ER-PM junctions formed near the leading edge of migrating cells (usually within 0.5 μm of polymerized actin and close to focal adhesions) and appeared suddenly without sliding from the interior of the cell. The long distance sliding and dissolution of ER-PM junctions accompanied the tail withdrawal.
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100
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Srikanth S, Ribalet B, Gwack Y. Regulation of CRAC channels by protein interactions and post-translational modification. Channels (Austin) 2013; 7:354-63. [PMID: 23454861 DOI: 10.4161/chan.23801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Store-operated Ca(2+) entry (SOCE) is a widespread mechanism to elevate the intracellular Ca(2+) concentrations and stimulate downstream signaling pathways affecting proliferation, secretion, differentiation and death in different cell types. In immune cells, immune receptor stimulation induces intracellular Ca(2+) store depletion that subsequently activates Ca(2+)-release-activated-Ca(2+) (CRAC) channels, a prototype of store-operated Ca(2+) (SOC) channels. CRAC channel opening leads to activation of diverse downstream signaling pathways affecting proliferation, differentiation, cytokine production and cell death. Recent identification of STIM1 as the endoplasmic reticulum Ca(2+) sensor and Orai1 as the pore subunit of CRAC channels has provided the much-needed molecular tools to dissect the mechanism of activation and regulation of CRAC channels. In this review, we discuss the recent advances in understanding the associating partners and posttranslational modifications of Orai1 and STIM1 proteins that regulate diverse aspects of CRAC channel function.
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Affiliation(s)
- Sonal Srikanth
- Department of Physiology; David Geffen School of Medicine at UCLA; Los Angeles, CA USA
| | - Bernard Ribalet
- Department of Physiology; David Geffen School of Medicine at UCLA; Los Angeles, CA USA
| | - Yousang Gwack
- Department of Physiology; David Geffen School of Medicine at UCLA; Los Angeles, CA USA
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