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Khani S, Topel H, Kardinal R, Tavanez AR, Josephrajan A, Larsen BDM, Gaudry MJ, Leyendecker P, Egedal NM, Güller AS, Stanic N, Ruppert PMM, Gaziano I, Hansmeier NR, Schmidt E, Klemm P, Vagliano LM, Stahl R, Duthie F, Krause JH, Bici A, Engelhard CA, Gohlke S, Frommolt P, Gnad T, Rada-Iglesias A, Pradas-Juni M, Schulz TJ, Wunderlich FT, Pfeifer A, Bartelt A, Jastroch M, Wachten D, Kornfeld JW. Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function. Nat Metab 2024; 6:1053-1075. [PMID: 38684889 DOI: 10.1038/s42255-024-01033-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 03/25/2024] [Indexed: 05/02/2024]
Abstract
Promoting brown adipose tissue (BAT) activity innovatively targets obesity and metabolic disease. While thermogenic activation of BAT is well understood, the rheostatic regulation of BAT to avoid excessive energy dissipation remains ill-defined. Here, we demonstrate that adenylyl cyclase 3 (AC3) is key for BAT function. We identified a cold-inducible promoter that generates a 5' truncated AC3 mRNA isoform (Adcy3-at), whose expression is driven by a cold-induced, truncated isoform of PPARGC1A (PPARGC1A-AT). Male mice lacking Adcy3-at display increased energy expenditure and are resistant to obesity and ensuing metabolic imbalances. Mouse and human AC3-AT are retained in the endoplasmic reticulum, unable to translocate to the plasma membrane and lack enzymatic activity. AC3-AT interacts with AC3 and sequesters it in the endoplasmic reticulum, reducing the pool of adenylyl cyclases available for G-protein-mediated cAMP synthesis. Thus, AC3-AT acts as a cold-induced rheostat in BAT, limiting adverse consequences of cAMP activity during chronic BAT activation.
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Affiliation(s)
- Sajjad Khani
- Institute for Genetics, University of Cologne, Cologne, Germany
- Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Hande Topel
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Novo Nordisk Foundation Center for Adipocyte Signaling (Adiposign), University of Southern Denmark, Odense, Denmark
| | - Ronja Kardinal
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Ana Rita Tavanez
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Novo Nordisk Foundation Center for Adipocyte Signaling (Adiposign), University of Southern Denmark, Odense, Denmark
| | - Ajeetha Josephrajan
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Novo Nordisk Foundation Center for Adipocyte Signaling (Adiposign), University of Southern Denmark, Odense, Denmark
| | | | - Michael James Gaudry
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Philipp Leyendecker
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Nadia Meincke Egedal
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Novo Nordisk Foundation Center for Adipocyte Signaling (Adiposign), University of Southern Denmark, Odense, Denmark
| | - Aylin Seren Güller
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Natasa Stanic
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Novo Nordisk Foundation Center for Adipocyte Signaling (Adiposign), University of Southern Denmark, Odense, Denmark
| | - Phillip M M Ruppert
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | | | - Elena Schmidt
- Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Paul Klemm
- Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Lara-Marie Vagliano
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Rainer Stahl
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Fraser Duthie
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Jens-Henning Krause
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany
| | - Ana Bici
- Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-University, Munich, Germany
| | - Christoph Andreas Engelhard
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sabrina Gohlke
- Department of Adipocyte Development and Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany
| | - Peter Frommolt
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Gnad
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
| | - Alvaro Rada-Iglesias
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/University of Cantabria, Santander, Spain
| | - Marta Pradas-Juni
- Novo Nordisk Foundation Center for Basic Metabolic Research (CBMR), Copenhagen, Denmark
| | - Tim Julius Schulz
- Department of Adipocyte Development and Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | | | - Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
| | - Alexander Bartelt
- Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-University, Munich, Germany
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Munich Heart Alliance, Munich, Germany
- Department of Molecular Metabolism and Sabri Ülker Center for Metabolic Research, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Martin Jastroch
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Dagmar Wachten
- Institute of Innate Immunity, Medical Faculty, University of Bonn, Bonn, Germany.
| | - Jan-Wilhelm Kornfeld
- Department for Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
- Novo Nordisk Foundation Center for Adipocyte Signaling (Adiposign), University of Southern Denmark, Odense, Denmark.
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2
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Mehta V, Khanppnavar B, Schuster D, Kantarci I, Vercellino I, Kosturanova A, Iype T, Stefanic S, Picotti P, Korkhov VM. Structure of Mycobacterium tuberculosis Cya, an evolutionary ancestor of the mammalian membrane adenylyl cyclases. eLife 2022; 11:77032. [PMID: 35980026 PMCID: PMC9433096 DOI: 10.7554/elife.77032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 08/17/2022] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium tuberculosis adenylyl cyclase (AC) Rv1625c / Cya is an evolutionary ancestor of the mammalian membrane ACs and a model system for studies of their structure and function. Although the vital role of ACs in cellular signaling is well established, the function of their transmembrane (TM) regions remains unknown. Here we describe the cryo-EM structure of Cya bound to a stabilizing nanobody at 3.6 Å resolution. The TM helices 1-5 form a structurally conserved domain that facilitates the assembly of the helical and catalytic domains. The TM region contains discrete pockets accessible from the extracellular and cytosolic side of the membrane. Neutralization of the negatively charged extracellular pocket Ex1 destabilizes the cytosolic helical domain and reduces the catalytic activity of the enzyme. The TM domain acts as a functional component of Cya, guiding the assembly of the catalytic domain and providing the means for direct regulation of catalytic activity in response to extracellular ligands.
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Affiliation(s)
- Ved Mehta
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Basavraj Khanppnavar
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Dina Schuster
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Ilayda Kantarci
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Irene Vercellino
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Angela Kosturanova
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Tarun Iype
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Sasa Stefanic
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Paola Picotti
- Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Volodymyr M Korkhov
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
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3
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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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4
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Pagano M, Clynes MA, Masada N, Ciruela A, Ayling LJ, Wachten S, Cooper DMF. Insights into the residence in lipid rafts of adenylyl cyclase AC8 and its regulation by capacitative calcium entry. Am J Physiol Cell Physiol 2009; 296:C607-19. [PMID: 19158400 PMCID: PMC2660271 DOI: 10.1152/ajpcell.00488.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenylyl cyclases (ACs) are a family of critically important signaling molecules that are regulated by multiple pathways. Adenylyl cyclase 8 (AC8) is a Ca(2+) stimulated isoform that displays a selective regulation by capacitative Ca(2+) entry (CCE), the process whereby the entry of Ca(2+) into cells is triggered by the emptying of intracellular stores. This selectivity was believed to be achieved through the localization of AC8 in lipid raft microdomains, along with components of the CCE apparatus. In the present study, we show that an intact leucine zipper motif is required for the efficient N-linked glycosylation of AC8, and that this N-linked glycosylation is important to target AC8 into lipid rafts. Disruption of the leucine zipper by site-directed mutagenesis results in the elimination of N-glycosylated forms and their exclusion from lipid rafts. Mutants of AC8 that cannot be N-glycosylated are not demonstrably associated with rafts, although they can still be regulated by CCE; however, raft integrity is required for the regulation of these mutants. These findings suggest that raft localized proteins in addition to AC8 are needed to mediate its regulation by CCE.
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Affiliation(s)
- Mario Pagano
- Dept. of Pharmacology, Univ. of Cambridge, Cambridge, CB2 1PD, United Kingdom
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5
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Thangavel M, Liu X, Sun SQ, Kaminsky J, Ostrom RS. The C1 and C2 domains target human type 6 adenylyl cyclase to lipid rafts and caveolae. Cell Signal 2008; 21:301-8. [PMID: 19007881 DOI: 10.1016/j.cellsig.2008.10.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 10/22/2008] [Accepted: 10/24/2008] [Indexed: 11/28/2022]
Abstract
Previous data has shown that adenylyl cyclase type 6 (AC6) is expressed principally in lipid rafts or caveolae of cardiac myocytes and other cell types while certain other isoforms of AC are excluded from these microdomains. The mechanism by which AC6 is localized to lipid rafts or caveolae is unknown. In this study, we show AC6 is localized in lipid rafts of COS-7 cells (expressing caveolin-1) and in HEK-293 cells or cardiac fibroblasts isolated from caveolin-1 knock-out mice (both of which lack prototypical caveolins). To determine the region of AC6 that confers raft localization, we independently expressed each of the major intracellular domains, the N-terminus, C1 and C2 domains, and examined their localization with various approaches. The N-terminus did not associate with lipid rafts or caveolae of either COS-7 or HEK-293 cells nor did it immunoprecipitate with caveolin-1 when expressed in COS-7 cells. By contrast, the C1 and C2 domains each associated with lipid rafts to varying degrees and were present in caveolin-1 immunoprecipitates. There were no differences in the pattern of localization of either the C1 or C2 domains between COS-7 and HEK-293 cells. Further dissection of the C1 domain into four individual proteins indicated that the N-terminal half of this domain is responsible for its raft localization. To probe for a role of a putative palmitoylation motif in the C-terminal portion of the C2 domain, we expressed various truncated forms of AC6 lacking most or all of the C-terminal 41 amino acids. These truncated AC6 proteins were not altered in terms of their localization in lipid rafts or their catalytic activity, implying that this C-terminal region is not required for lipid raft targeting of AC6. We conclude that while the C1 domain may be most important, both the C1 and C2 domains of AC6 play a role in targeting AC6 to lipid rafts.
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Affiliation(s)
- Muthusamy Thangavel
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, United States
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6
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Baragli A, Grieco ML, Trieu P, Villeneuve LR, Hébert TE. Heterodimers of adenylyl cyclases 2 and 5 show enhanced functional responses in the presence of Galpha s. Cell Signal 2007; 20:480-92. [PMID: 18164588 DOI: 10.1016/j.cellsig.2007.10.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 10/30/2007] [Indexed: 12/22/2022]
Abstract
Recent studies have demonstrated that adenylyl cyclase isoforms can form both homo- and heterodimers and that this may be the basic functional unit of these enzymes (see Cooper, D.M.F. and Crossthwaite, A.J. (2006) Trends. Pharmacol. Sci. 8:426-431). Here, we show that adenylyl cyclases 2 and 5 can form a functional heterodimeric complex in HEK293 cells using a combination of BRET, confocal imaging, co-immunoprecipitation and assays of adenylyl cyclase activity. The AC2/5 complex is formed constitutively and is stable in the presence of receptor or forskolin stimulation. The complex formed by AC2/5 is also much more sensitive to the presence of Galpha(s) and forskolin than either of the parent AC isoforms themselves. Finally, we also show that this complex can be detected in native tissues as AC2 and AC5 were localized to the same structures in adult mouse ventricular myocytes and neonatal mouse cardiac fibroblasts and could be co-immunoprecipitated from lysates of mouse heart.
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Affiliation(s)
- Alessandra Baragli
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Quebec, Canada
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7
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Willoughby D, Cooper DMF. Organization and Ca2+Regulation of Adenylyl Cyclases in cAMP Microdomains. Physiol Rev 2007; 87:965-1010. [PMID: 17615394 DOI: 10.1152/physrev.00049.2006] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The adenylyl cyclases are variously regulated by G protein subunits, a number of serine/threonine and tyrosine protein kinases, and Ca2+. In some physiological situations, this regulation can be readily incorporated into a hormonal cascade, controlling processes such as cardiac contractility or neurotransmitter release. However, the significance of some modes of regulation is obscure and is likely only to be apparent in explicit cellular contexts (or stages of the cell cycle). The regulation of many of the ACs by the ubiquitous second messenger Ca2+provides an overarching mechanism for integrating the activities of these two major signaling systems. Elaborate devices have been evolved to ensure that this interaction occurs, to guarantee the fidelity of the interaction, and to insulate the microenvironment in which it occurs. Subcellular targeting, as well as a variety of scaffolding devices, is used to promote interaction of the ACs with specific signaling proteins and regulatory factors to generate privileged domains for cAMP signaling. A direct consequence of this organization is that cAMP will exhibit distinct kinetics in discrete cellular domains. A variety of means are now available to study cAMP in these domains and to dissect their components in real time in live cells. These topics are explored within the present review.
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Affiliation(s)
- Debbie Willoughby
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
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8
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Feldman RD, Gros R. New insights into the regulation of cAMP synthesis beyond GPCR/G protein activation: implications in cardiovascular regulation. Life Sci 2007; 81:267-71. [PMID: 17604058 DOI: 10.1016/j.lfs.2007.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 04/12/2007] [Accepted: 05/19/2007] [Indexed: 11/25/2022]
Abstract
Regulation of intracellular concentrations of cyclic AMP is one of the most ubiquitous mechanisms for regulating cellular functions. Further, the manner in which cAMP production is regulated via G proteins at the level of adenylyl cyclase activation has been studied extensively. This review focuses instead on the recently identified mechanisms and roles for regulation of adenylyl cyclase functions beyond G protein activation. These mechanisms include: a) the coupling of particular isoforms of adenylyl cyclase to function within a single cell type b) regulation of membrane trafficking of higher order enzyme aggregates and c) raf kinase-dependent phosphorylation and sensitization of adenylyl cyclases--an important pathway for crosstalk between tyrosine kinase signaling cascades with regulation of cAMP-mediated responses.
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Affiliation(s)
- Ross D Feldman
- Cell Biology and Vascular Biology Research Groups, Robarts Research Institute, London, Ontario, Canada.
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9
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Gros R, Ding Q, Chorazyczewski J, Pickering JG, Limbird LE, Feldman RD. Adenylyl cyclase isoform-selective regulation of vascular smooth muscle proliferation and cytoskeletal reorganization. Circ Res 2006; 99:845-52. [PMID: 16973907 DOI: 10.1161/01.res.0000245189.21703.c0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Compartmentation of cAMP signaling been demonstrated to be attributable to the structural association of protein kinase A (PKA) (via association with A-kinase anchoring proteins [AKAPs]) with phosphodiesterase and AKAP-dependent effector molecules. However, other mechanisms contributing to compartmentalization have not been rigorously explored, including the possibility that different isoforms of adenylyl cyclase (AC) may be functionally "compartmentalized" because of differential association with tethering or signaling molecules. To this end, we examined the effect of adenoviral transduction of representative AC isoforms (AC1, AC2, AC5, and AC6) on cellular cAMP production, PKA activation, extracellular signal-regulated kinase (ERK) activation, cell doubling and proliferation, as well as arborization responses (an index of cAMP-mediated cytoskeletal re-organization) in vascular smooth muscle cells. When isoforms were expressed at levels to achieve comparable forskolin-stimulated AC activity, only gene transfer of AC6 significantly enhanced PKA-dependent vasodilator-stimulated phosphoprotein (VASP) phosphorylation and arborization responses. Treatment of control cells, which express AC6 endogenously, as well as vascular smooth overexpressing the AC6 isoform with small interfering RNA directed against AC6, significantly suppressed both isoproterenol-stimulated cAMP accumulation and arborization. Notably, the selective effects of AC6 expression were abrogated in the presence of phosphodiesterase suppression. In contrast, only the expression of AC1 enhanced forskolin-stimulated association of ERK with AC, demonstrated by coimmuno-isolation of ERK with Flag-tagged AC1, but not with Flag-tagged AC6. To determine whether these isoform-selective effects of AC were unique to differentiated and morphologically compartmentalized vascular smooth muscle cells or were a general property of these isoforms, we examined the consequence of expression of these various isoforms in human embryonic kidney (HEK) cells. Indeed, we observed similar isoform-dependent association of AC1 with ERK, activation of ERK by stimulation of AC1 with forskolin, and AC1-dependent lengthening of doubling time, indicating that these properties of AC1 are cell autologous and likely result from AC1-dependent protein-protein interactions. In aggregate, these findings suggest that isoform-selective signaling complexes likely contribute to various functional consequences of cAMP elevation in vascular smooth muscle cells.
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Affiliation(s)
- Robert Gros
- Cell Biology Research Group, Robarts Research Institute, 100 Perth Dr, London, ON N6A 5K8, Canada
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10
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Cooper DMF, Crossthwaite AJ. Higher-order organization and regulation of adenylyl cyclases. Trends Pharmacol Sci 2006; 27:426-31. [PMID: 16820220 DOI: 10.1016/j.tips.2006.06.002] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 04/26/2006] [Accepted: 06/16/2006] [Indexed: 11/26/2022]
Abstract
There is increasing awareness of the compartmentalization of cAMP signalling--the means by which cAMP levels change in discrete domains of the cell with discrete local consequences. Current developments in understanding the organization of adenylyl cyclases in the plasma membrane are illuminating how the earliest part of cAMP compartmentalization could occur. This review focuses on recent findings regarding three levels of adenylyl cyclase organization--oligomerization, positioning to lipid rafts and participation in multiprotein signalling complexes. This organization, coupled with the role of scaffolding proteins in arranging the downstream effectors of cAMP, helps to identify complexes that greatly facilitate the translation of enzyme activation into local consequences.
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Affiliation(s)
- Dermot M F Cooper
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK.
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11
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Abstract
Concepts of cAMP signalling have changed dramatically from the linear cascades of just a few years ago, with the realization that numerous cellular processes affect this motif. These influences include other signalling pathways--most significantly Ca2+, scaffolding proteins (which are themselves variously regulated) to organize the elements of the pathway, and subcellular targeting of components. An obvious implication of this organization is that global measurements of cAMP may trivialize the complexity of the cAMP signals and obscure the regulation of targets. In this presentation, current developments on the targeting and assembly of ACs (adenylate cyclases) and their delivery to selected raft or non-raft domains of the plasma membrane will be discussed, along with the susceptibility of raft-targeted ACs to very discrete modes of increases in the intracellular Ca2+ concentration. Single-cell explorations of cAMP dynamics, as measured with cyclic nucleotide-gated channels, are also described in this paper, particularly as applied to cells in which the composition of AKAP (A-kinase anchoring protein)-PKA (protein kinase A)-PDE (phosphodiesterase) assemblies is probed by RNA interference ablation of defined AKAPs.
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