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Glebov-McCloud AGP, Saide WS, Gaine ME, Strack S. Protein Kinase A in neurological disorders. J Neurodev Disord 2024; 16:9. [PMID: 38481146 PMCID: PMC10936040 DOI: 10.1186/s11689-024-09525-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 02/29/2024] [Indexed: 03/17/2024] Open
Abstract
Cyclic adenosine 3', 5' monophosphate (cAMP)-dependent Protein Kinase A (PKA) is a multi-functional serine/threonine kinase that regulates a wide variety of physiological processes including gene transcription, metabolism, and synaptic plasticity. Genomic sequencing studies have identified both germline and somatic variants of the catalytic and regulatory subunits of PKA in patients with metabolic and neurodevelopmental disorders. In this review we discuss the classical cAMP/PKA signaling pathway and the disease phenotypes that result from PKA variants. This review highlights distinct isoform-specific cognitive deficits that occur in both PKA catalytic and regulatory subunits, and how tissue-specific distribution of these isoforms may contribute to neurodevelopmental disorders in comparison to more generalized endocrine dysfunction.
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Affiliation(s)
- Alexander G P Glebov-McCloud
- Department of Neuroscience and Pharmacology, Bowen Science Building, University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, IA, 52242, USA
| | - Walter S Saide
- Department of Neuroscience and Pharmacology, Bowen Science Building, University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, IA, 52242, USA
| | - Marie E Gaine
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy Building, College of Pharmacy, University of Iowa, 180 S. Grand Ave, Iowa City, IA, 52242, USA
- Iowa Neuroscience Institute, Intellectual and Developmental Disabilities Research Center, Iowa City, IA, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, Bowen Science Building, University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, IA, 52242, USA.
- Iowa Neuroscience Institute, Intellectual and Developmental Disabilities Research Center, Iowa City, IA, USA.
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2
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Polishchuk A, Cilleros-Mañé V, Just-Borràs L, Balanyà-Segura M, Vandellòs Pont G, Silvera Simón C, Tomàs M, Garcia N, Tomàs J, Lanuza MA. Synaptic retrograde regulation of the PKA-induced SNAP-25 and Synapsin-1 phosphorylation. Cell Mol Biol Lett 2023; 28:17. [PMID: 36869288 PMCID: PMC9985302 DOI: 10.1186/s11658-023-00431-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 02/09/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Bidirectional communication between presynaptic and postsynaptic components contribute to the homeostasis of the synapse. In the neuromuscular synapse, the arrival of the nerve impulse at the presynaptic terminal triggers the molecular mechanisms associated with ACh release, which can be retrogradely regulated by the resulting muscle contraction. This retrograde regulation, however, has been poorly studied. At the neuromuscular junction (NMJ), protein kinase A (PKA) enhances neurotransmitter release, and the phosphorylation of the molecules of the release machinery including synaptosomal associated protein of 25 kDa (SNAP-25) and Synapsin-1 could be involved. METHODS Accordingly, to study the effect of synaptic retrograde regulation of the PKA subunits and its activity, we stimulated the rat phrenic nerve (1 Hz, 30 min) resulting or not in contraction (abolished by µ-conotoxin GIIIB). Changes in protein levels and phosphorylation were detected by western blotting and cytosol/membrane translocation by subcellular fractionation. Synapsin-1 was localized in the levator auris longus (LAL) muscle by immunohistochemistry. RESULTS Here we show that synaptic PKA Cβ subunit regulated by RIIβ or RIIα subunits controls activity-dependent phosphorylation of SNAP-25 and Synapsin-1, respectively. Muscle contraction retrogradely downregulates presynaptic activity-induced pSynapsin-1 S9 while that enhances pSNAP-25 T138. Both actions could coordinately contribute to decreasing the neurotransmitter release at the NMJ. CONCLUSION This provides a molecular mechanism of the bidirectional communication between nerve terminals and muscle cells to balance the accurate process of ACh release, which could be important to characterize molecules as a therapy for neuromuscular diseases in which neuromuscular crosstalk is impaired.
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Affiliation(s)
- Aleksandra Polishchuk
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Víctor Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Laia Just-Borràs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Marta Balanyà-Segura
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Genís Vandellòs Pont
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Carolina Silvera Simón
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain
| | - Josep Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain.
| | - Maria A Lanuza
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, c/ Sant Llorenç 21, 43201, Reus, Spain.
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3
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London E, Stratakis CA. The regulation of PKA signaling in obesity and in the maintenance of metabolic health. Pharmacol Ther 2022; 237:108113. [PMID: 35051439 DOI: 10.1016/j.pharmthera.2022.108113] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/03/2022] [Accepted: 01/11/2022] [Indexed: 12/13/2022]
Abstract
The cAMP-dependent protein kinase (PKA) system represents a primary cell-signaling pathway throughout systems and across species. PKA facilitates the actions of hormones, neurotransmitters and other signaling molecules that bind G-protein coupled receptors (GPCR) to modulate cAMP levels. Through its control of synaptic events, exocytosis, transcriptional regulation, and more, PKA signaling regulates cellular metabolism and emotional and stress responses making it integral in the maintenance and dysregulation of energy homeostasis. Neural PKA signaling is regulated by afferent and peripheral efferent signals that link specific neural cell populations to the regulation of metabolic processes in adipose tissue, liver, pancreas, adrenal, skeletal muscle, and gut. Mouse models have provided invaluable information on the roles for PKA subunits in brain and key metabolic organs. While limited, human studies infer differential regulation of the PKA system in obese compared to lean individuals. Variants identified in PKA subunit genes cause Cushing syndrome that is characterized by metabolic dysregulation associated with endogenous glucocorticoid excess. Under healthy physiologic conditions, the PKA system is exquisitely regulated by stimuli that activate GPCRs to alter intracellular cAMP concentrations, and by PKA cellular localization and holoenzyme stability. Adenylate cyclase activity generates cAMP while phosphodiesterase-mediated cAMP degradation to AMP decreases cAMP levels downstream of GPCRs. Chronic perturbations in PKA signaling appear to be capable of resetting PKA regulation at several levels; in addition, sex differences in PKA signaling regulation, while not well understood, impact the physiologic consequences of metabolic dysregulation and obesity. This review explores the roles for PKA signaling in the pathogenesis of metabolic diseases including obesity, type 2 diabetes mellitus and associated co-morbidities through neural-peripheral crosstalk and cAMP/PKA signaling pathway targets that hold therapeutic potential.
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Affiliation(s)
- Edra London
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, USA.
| | - Constantine A Stratakis
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, USA; Human Genetics & Precision Medicine, IMBB, Foundation for Research & Technology Hellas, Greece; Research Institute, ELPEN, SA, Athens, Greece
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4
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Cai E, Zhang J, Ge X. Control of the Hedgehog pathway by compartmentalized PKA in the primary cilium. SCIENCE CHINA-LIFE SCIENCES 2021; 65:500-514. [PMID: 34505970 DOI: 10.1007/s11427-021-1975-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/01/2021] [Indexed: 01/20/2023]
Abstract
The Hedgehog (Hh) signaling is one of the essential signaling pathways during embryogenesis and in adults. Hh signal transduction relies on primary cilium, a specialized cell surface organelle viewed as the hub of cell signaling. Protein kinase A (PKA) has been recognized as a potent negative regulator of the Hh pathway, raising the question of how such a ubiquitous kinase specifically regulates one signaling pathway. We reviewed recent genetic, molecular and biochemical studies that have advanced our mechanistic understanding of PKA's role in Hh signaling in vertebrates, focusing on the compartmentalized PKA at the centrosome and in the primary cilium. We outlined the recently developed genetic and optical tools that can be harvested to study PKA activities during the course of Hh signal transduction.
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Affiliation(s)
- Eva Cai
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA, 95340, USA
| | - Jingyi Zhang
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA, 95340, USA
| | - Xuecai Ge
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, CA, 95340, USA.
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5
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Taylor SS, Søberg K, Kobori E, Wu J, Pautz S, Herberg FW, Skålhegg BS. The tails of PKA. Mol Pharmacol 2021; 101:219-225. [PMID: 34330820 DOI: 10.1124/molpharm.121.000315] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/23/2021] [Indexed: 11/22/2022] Open
Abstract
The catalytic subunit of PKA is regulated by two tails that each wrap around the N- and C-lobes of the kinase core. While the Ct-Tail is classified as an intrinsically disordered region (IDR), the Nt-Tail is dominated by a strong helix that is flanked by short IDRs. In contrast to the Ct-Tail, which is a conserved and highly regulated feature of all AGC kinases, the Nt-Tail has evolved more recently and is not even conserved in non-mammalian PKAs. In addition, and most importantly, there is a large family of Cb subunits that are highly expressed in mammalian cells in a tissue-specific manner. While we know so much about the Ca1 subunit, we know almost nothing about these Cb isoforms where Cb2 is highly expressed in lymphocytes and Cb3 and Cb4 isoforms account for ~50% of PKA signaling in brain. Based on recent disease mutations, the Cb proteins appear to be functionally important and non-redundant with the Ca isoforms. Imaging in retina also supports non-redundant roles for Cb as well as isoform-specific localization to mitochondria. This represents a new frontier in PKA signaling. Significance Statement How tails and adjacent domains regulate each protein kinase is a fundamental challenge for the biological community. Here we highlight how the N- and C-terminal tails of PKA (Nt-Tails/Ct-Tails) regulate the structure and function of the kinase core and show the combinatorial variations that are introduced into the Nt-Tail of the Ca and Cb subunits of PKA in contrast to the Ct-Tail which is conserved across the entire AGC subfamily of protein kinases.
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Affiliation(s)
| | - Kristoffer Søberg
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway, Norway
| | - Evan Kobori
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0654,, United States
| | - Jian Wu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0654,, United States
| | - Sabine Pautz
- Department of Biochemistry, University of Kassel, 34132 Kassel, Germany, Germany
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6
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PKA Cβ: a forgotten catalytic subunit of cAMP-dependent protein kinase opens new windows for PKA signaling and disease pathologies. Biochem J 2021; 478:2101-2119. [PMID: 34115095 DOI: 10.1042/bcj20200867] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 12/17/2022]
Abstract
3',5'-cyclic adenosine monophosphate (cAMP) dependent protein kinase or protein kinase A (PKA) has served as a prototype for the large family of protein kinases that are crucially important for signal transduction in eukaryotic cells. The PKA catalytic subunits are encoded by the two major genes PRKACA and PRKACB, respectively. The PRKACA gene encodes two known splice variants, the ubiquitously expressed Cα1 and the sperm-specifically expressed Cα2. In contrast, the PRKACB gene encodes several splice variants expressed in a highly cell and tissue-specific manner. The Cβ proteins are called Cβ1, Cβ2, Cβ3, Cβ4 and so-called abc variants of Cβ3 and Cβ4. Whereas Cβ1 is ubiquitously expressed, Cβ2 is enriched in immune cells and the Cβ3, Cβ4 and their abc variants are solely expressed in neuronal cells. All Cα and Cβ splice variants share a kinase-conserved catalytic core and a C-terminal tail encoded by exons 2 through 10 in the PRKACA and PRKACB genes, respectively. All Cα and Cβ splice variants with the exception of Cα1 and Cβ1 are hyper-variable at the N-terminus. Here, we will discuss how the PRKACA and PRKACB genes have developed as paralogs that encode distinct and functionally non-redundant proteins. The fact that Cα and Cβ splice variant mutations are associated with numerous diseases further opens new windows for PKA-induced disease pathologies.
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7
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Taylor SS, Wu J, Bruystens JGH, Del Rio JC, Lu TW, Kornev AP, Ten Eyck LF. From structure to the dynamic regulation of a molecular switch: A journey over 3 decades. J Biol Chem 2021; 296:100746. [PMID: 33957122 PMCID: PMC8144671 DOI: 10.1016/j.jbc.2021.100746] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/16/2021] [Accepted: 04/30/2021] [Indexed: 12/14/2022] Open
Abstract
It is difficult to imagine where the signaling community would be today without the Protein Data Bank. This visionary resource, established in the 1970s, has been an essential partner for sharing information between academics and industry for over 3 decades. We describe here the history of our journey with the protein kinases using cAMP-dependent protein kinase as a prototype. We summarize what we have learned since the first structure, published in 1991, why our journey is still ongoing, and why it has been essential to share our structural information. For regulation of kinase activity, we focus on the cAMP-binding protein kinase regulatory subunits. By exploring full-length macromolecular complexes, we discovered not only allostery but also an essential motif originally attributed to crystal packing. Massive genomic data on disease mutations allows us to now revisit crystal packing as a treasure chest of possible protein:protein interfaces where the biological significance and disease relevance can be validated. It provides a new window into exploring dynamic intrinsically disordered regions that previously were deleted, ignored, or attributed to crystal packing. Merging of crystallography with cryo-electron microscopy, cryo-electron tomography, NMR, and millisecond molecular dynamics simulations is opening a new world for the signaling community where those structure coordinates, deposited in the Protein Data Bank, are just a starting point!
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Affiliation(s)
- Susan S Taylor
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA; Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, California, USA.
| | - Jian Wu
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Jessica G H Bruystens
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Jason C Del Rio
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Tsan-Wen Lu
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA
| | - Alexandr P Kornev
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Lynn F Ten Eyck
- Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, California, USA; San Diego Supercomputer Center, University of California at San Diego, San Diego, California, USA
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8
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Postler TS. A most versatile kinase: The catalytic subunit of PKA in T-cell biology. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 361:301-318. [PMID: 34074497 DOI: 10.1016/bs.ircmb.2021.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cAMP-dependent protein kinase, more commonly referred to as protein kinase A (PKA), is one of the most-studied enzymes in biology. PKA is ubiquitously expressed in mammalian cells, can be activated in response to a plethora of biological stimuli, and phosphorylates more than 250 known substrates. Indeed, PKA is of central importance to a wide range of organismal processes, including energy homeostasis, memory formation and immunity. It serves as the primary effector of the second-messenger molecule 3',5'-cyclic adenosine monophosphate (cAMP), which is believed to have mostly inhibitory effects on the adaptive immune response. In particular, elevated levels of intracellular cAMP inhibit the activation of conventional T cells by limiting signal transduction through the T-cell receptor and altering gene expression, primarily in a PKA-dependent manner. Regulatory T cells have been shown to increase the cAMP levels in adjacent T cells by direct and indirect means, but the role of cAMP within regulatory T cells themselves remains incompletely understood. Paradoxically, cAMP has been implicated in promoting T-cell activation as well, adding another functional dimension beyond its established immunosuppressive effects. Furthermore, PKA can phosphorylate the NF-κB subunit p65, a transcription factor that is essential for T-cell activation, independently of cAMP. This phosphorylation of p65 drastically enhances NF-κB-dependent transcription and thus is likely to facilitate immune activation. How these immunosuppressive and immune-activating properties of PKA balance in vivo remains to be elucidated. This review provides a brief overview of PKA regulation, its ability to affect NF-κB activation, and its diverse functions in T-cell biology.
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Affiliation(s)
- Thomas S Postler
- Department of Microbiology & Immunology, Vagelos College of Physicians & Surgeons, Columbia University Irving Medical Center, New York, NY, United States.
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9
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Baro Graf C, Ritagliati C, Stival C, Luque GM, Gentile I, Buffone MG, Krapf D. Everything you ever wanted to know about PKA regulation and its involvement in mammalian sperm capacitation. Mol Cell Endocrinol 2020; 518:110992. [PMID: 32853743 DOI: 10.1016/j.mce.2020.110992] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 12/29/2022]
Abstract
The 3', 5'-cyclic adenosine monophosphate (cAMP) dependent protein kinase (PKA) is a tetrameric holoenzyme comprising a set of two regulatory subunits (PKA-R) and two catalytic (PKA-C) subunits. The PKA-R subunits act as sensors of cAMP and allow PKA-C activity. One of the first signaling events observed during mammalian sperm capacitation is PKA activation. Thus, understanding how PKA activity is restricted in space and time is crucial to decipher the critical steps of sperm capacitation. It is widely accepted that PKA specificity depends on several levels of regulation. Anchoring proteins play a pivotal role in achieving proper localization signaling, subcellular targeting and cAMP microdomains. These multi-factorial regulation steps are necessary for a precise spatio-temporal activation of PKA. Here we discuss recent understanding of regulatory mechanisms of PKA in mammalian sperm, such as post-translational modifications, in the context of its role as the master orchestrator of molecular events conducive to capacitation.
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Affiliation(s)
- Carolina Baro Graf
- Laboratory of Cell Signal Transduction Networks, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario, Argentina; Laboratorio de Medicina Reproductiva (LMR), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Carla Ritagliati
- Laboratory of Cell Signal Transduction Networks, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario, Argentina
| | - Cintia Stival
- Laboratory of Cell Signal Transduction Networks, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario, Argentina
| | - Guillermina M Luque
- Laboratory of Cellular and Molecular Reproductive Biology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Iñaki Gentile
- Laboratory of Cell Signal Transduction Networks, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario, Argentina
| | - Mariano G Buffone
- Laboratory of Cellular and Molecular Reproductive Biology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires, Argentina
| | - Dario Krapf
- Laboratory of Cell Signal Transduction Networks, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario, Argentina; Laboratorio de Medicina Reproductiva (LMR), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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10
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London E, Bloyd M, Stratakis CA. PKA functions in metabolism and resistance to obesity: lessons from mouse and human studies. J Endocrinol 2020; 246:R51-R64. [PMID: 32485681 PMCID: PMC7385994 DOI: 10.1530/joe-20-0035] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 05/19/2020] [Indexed: 12/12/2022]
Abstract
Both direct and indirect evidence demonstrate a central role for the cAMP-dependent protein kinase (PKA) signaling pathway in the regulation of energy balance and metabolism across multiple systems. However, the ubiquitous pattern of PKA expression across cell types poses a challenge in pinpointing its tissue-specific regulatory functions and further characterizing its many downstream effects in certain organs or cells. Mouse models of PKA deficiency and over-expression and studies in living cells have helped clarify PKA function in adipose tissue (AT), liver, adrenal, pancreas, and specific brain nuclei, as they pertain to energy balance and metabolic dysregulation. Limited studies in humans suggest differential regulation of PKA in AT of obese compared to lean individuals and an overall dysregulation of PKA signaling in obesity. Despite its complexity, under normal physiologic conditions, the PKA system is tightly regulated by changes in cAMP concentrations upstream via adenylate cyclase and downstream by phosphodiesterase-mediated cAMP degradation to AMP and by changes in PKA holoenzyme stability. Adjustments in the PKA system appear to be important to the development and maintenance of the obese state and its associated metabolic perturbations. In this review we discuss the important role of PKA in obesity and its involvement in resistance to obesity, through studies in humans and in mouse models, with a focus on the regulation of PKA in energy expenditure, intake behavior, and lipid and glucose metabolism.
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Affiliation(s)
- Edra London
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
| | - Michelle Bloyd
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
| | - Constantine A. Stratakis
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
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11
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Zhao C. Identifying the hub gene and immune infiltration of osteoarthritis by bioinformatical methods. Clin Rheumatol 2020; 40:1027-1037. [PMID: 32785809 DOI: 10.1007/s10067-020-05311-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND Nowadays, there are more and more people who have been diagnosed osteoarthritis (OA). However, due to the complex changes of OA, the treatment outcome is not very well. In order to improve this situation, I decided to aggregate a series of data and use complex bioinformatical methods to analyze them, hoping to explore new therapeutic targets. METHODS After downloading and processing the data from Gene Expression Omnibus (GEO) database, I analyzed the relationship between genes and OA formation by the weighted correlation network analysis (WGCNA)and selected the turquoise module which owned the closest relationship with clinical traits. Then, via online database and CIBERSORT algorithm method, I analyzed the function of this key module and the situation of immune infiltration in OA tissues. RESULTS With the help of WGCNA and functional enrichment analysis, I found out that most of genes in the turquoise module took part in the inflammation development, immune responses, and cell proliferation, especially the hub gene PRKACB. At the same time, my results of immune infiltration and expression level analysis also showed that PRKACB has a close relationship with immune cells, especially M2 macrophage. CONCLUSION In a word, my results suggested that PRKACB played an essential role in osteoarthritis development. Key Points • Used the "sva" R package to combine the data of 59 samples from four studies to do the bioinformatical analysis. • Identifying the hub gene PRKACB as potential marker for OA and using validation sets to confirm it. • Detecting the situation of immune infiltration in synovium by CIBERSORT algorithm method.
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Affiliation(s)
- Chengmao Zhao
- Zibo Municipal Hospital, Zibo, 255400, Shandong, China.
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12
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Swimming regulations for protein kinase A catalytic subunit. Biochem Soc Trans 2020; 47:1355-1366. [PMID: 31671183 DOI: 10.1042/bst20190230] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/05/2019] [Accepted: 09/10/2019] [Indexed: 11/17/2022]
Abstract
cAMP-dependent protein kinase (PKA) plays a central role in important biological processes including synaptic plasticity and sympathetic stimulation of the heart. Elevations of cAMP trigger release of PKA catalytic (C) subunits from PKA holoenzymes, thereby coupling cAMP to protein phosphorylation. Uncontrolled C subunit activity, such as occurs in genetic disorders in which regulatory subunits are depleted, is pathological. Anchoring proteins that associate with PKA regulatory subunits are important for localising PKA activity in cells. However, anchoring does not directly explain how unrestrained 'free swimming' of C subunits is avoided following C subunit release. In this review, I discuss new mechanisms that have been posited to account for this old problem. One straightforward explanation is that cAMP does not trigger C subunit dissociation but instead activates intact PKA holoenzymes whose activity is restrained through anchoring. A comprehensive comparison of observations for and against cAMP-activation of intact PKA holoenzymes does not lend credence to this mechanism. Recent measurements have revealed that PKA regulatory subunits are expressed at very high concentrations, and in large molar excess relative to C subunits. I discuss the implications of these skewed PKA subunit concentrations, before considering how phosphorylation of type II regulatory subunits and myristylation of C subunits are likely to contribute to controlling C subunit diffusion and recapture in cells. Finally, I speculate on future research directions that may be pursued on the basis of these emerging mechanisms.
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Cilleros-Mañé V, Just-Borràs L, Tomàs M, Garcia N, Tomàs JM, Lanuza MA. The M 2 muscarinic receptor, in association to M 1 , regulates the neuromuscular PKA molecular dynamics. FASEB J 2020; 34:4934-4955. [PMID: 32052889 DOI: 10.1096/fj.201902113r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/23/2019] [Accepted: 01/20/2020] [Indexed: 01/13/2023]
Abstract
Muscarinic acetylcholine receptor 1 subtype (M1 ) and muscarinic acetylcholine receptor 2 subtype (M2 ) presynaptic muscarinic receptor subtypes increase and decrease, respectively, neurotransmitter release at neuromuscular junctions. M2 involves protein kinase A (PKA), although the muscarinic regulation to form and inactivate the PKA holoenzyme is unknown. Here, we show that M2 signaling inhibits PKA by downregulating Cβ subunit, upregulating RIIα/β and liberating RIβ and RIIα to the cytosol. This promotes PKA holoenzyme formation and reduces the phosphorylation of the transmitter release target synaptosome-associated protein 25 and the gene regulator cAMP response element binding. Instead, M1 signaling, which is downregulated by M2 , opposes to M2 by recruiting R subunits to the membrane. The M1 and M2 reciprocal actions are performed through the anchoring protein A kinase anchor protein 150 as a common node. Interestingly, M2 modulation on protein expression needs M1 signaling. Altogether, these results describe the dynamics of PKA subunits upon M2 muscarinic signaling in basal and under presynaptic nerve activity, uncover a specific involvement of the M1 receptor and reveal the M1 /M2 balance to activate PKA to regulate neurotransmission. This provides a molecular mechanism to the PKA holoenzyme formation and inactivation which could be general to other synapses and cellular models.
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Affiliation(s)
- Víctor Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Laia Just-Borràs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Josep Maria Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - Maria Angel Lanuza
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
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Neuronal cAMP/PKA Signaling and Energy Homeostasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1090:31-48. [PMID: 30390284 DOI: 10.1007/978-981-13-1286-1_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The brain plays a key role in the regulation of body weight and glucose metabolism. Peripheral signals including hormones, metabolites, and neural afferent signals are received and processed by the brain which in turn elicits proper behavioral and metabolic responses for maintaining energy and glucose homeostasis. The cAMP/protein kinase A (PKA) pathway acts downstream G-protein-coupled receptors (GPCR) to mediate the physiological effects of many hormones and neurotransmitters. Activated PKA phosphorylates various proteins including ion channels, enzymes, and transcription factors and regulates their activity. Recent studies have shown that neuronal cAMP/PKA activity in multiple brain regions are involved in the regulation of feeding, energy expenditure, and glucose homeostasis. In this chapter I summarize recent genetic and pharmacological studies concerning the regulation of body weight and glucose homeostasis by cAMP/PKA signaling in the brain.
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London E, Noguchi A, Springer D, Faidas M, Gavrilova O, Eisenhofer G, Stratakis CA. The Catalytic Subunit β of PKA Affects Energy Balance and Catecholaminergic Activity. J Endocr Soc 2019; 3:1062-1078. [PMID: 31073546 PMCID: PMC6503631 DOI: 10.1210/js.2019-00029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 03/22/2019] [Indexed: 01/20/2023] Open
Abstract
The protein kinase A (PKA) signaling system mediates the effects of numerous hormones, neurotransmitters, and other molecules to regulate metabolism, cardiac function, and more. PKA defects may lead to diverse phenotypes that largely depend on the unique expression profile of the affected subunit. Deletion of the Prkarcb gene, which codes for PKA catalytic subunit β (Cβ), protects against diet-induced obesity (DIO), yet the mechanism for this phenotype remains unclear. We hypothesized that metabolic rate would be increased in Cβ knockout (KO) mice, which could explain DIO resistance. Male, but not female, CβKO mice had increased energy expenditure, and female but not male CβKO mice had increased subcutaneous temperature and increased locomotor activity compared with wild-type (WT) littermates. Urinary norepinephrine (NE) and normetanephrine were elevated in female CβKO mice. CβKO mice had increased heart rate (HR); blocking central NE release normalized HR to that of untreated WT mice. Basal and stimulated PKA enzymatic activities were unchanged in adipose tissue and heart and varied in different brain regions, suggesting that Prkacb deletion may mediate signaling changes in specific brain nuclei and may be less important in the peripheral regulation of PKA expression and activity. This is a demonstration of a distinct effect of the PKA Cβ catalytic subunit on catecholamines and sympathetic nerve signaling. The data provide an unexpected explanation for the metabolic phenotype of CβKO mice. Finally, the sexual dimorphism is consistent with mouse models of other PKA subunits and adds to the importance of these findings regarding the PKA system in human metabolism.
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Affiliation(s)
- Edra London
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Audrey Noguchi
- Murine Phenotyping Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Danielle Springer
- Murine Phenotyping Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Maria Faidas
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Oksana Gavrilova
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Graeme Eisenhofer
- Department of Medicine III Techniche Universität Dresden, Dresden, Germany.,Institute of Clinical Chemistry and Laboratory Medicine, Techniche Universitat Dresden, Dresden, Germany
| | - Constantine A Stratakis
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
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16
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Jin N, Ma D, Gu J, Shi J, Xu X, Iqbal K, Gong CX, Liu F, Chu D. O-GlcNAcylation modulates PKA-CREB signaling in a manner specific to PKA catalytic subunit isoforms. Biochem Biophys Res Commun 2018; 497:194-199. [DOI: 10.1016/j.bbrc.2018.02.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 02/05/2018] [Indexed: 11/29/2022]
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17
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Søberg K, Skålhegg BS. The Molecular Basis for Specificity at the Level of the Protein Kinase a Catalytic Subunit. Front Endocrinol (Lausanne) 2018; 9:538. [PMID: 30258407 PMCID: PMC6143667 DOI: 10.3389/fendo.2018.00538] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/24/2018] [Indexed: 12/16/2022] Open
Abstract
Assembly of multi enzyme complexes at subcellular localizations by anchoring- and scaffolding proteins represents a pivotal mechanism for achieving spatiotemporal regulation of cellular signaling after hormone receptor targeting [for review, see (1)]. In the 3' 5'-cyclic adenosine monophosphate (cAMP) dependent protein kinase (PKA) signaling pathway it is generally accepted that specificity is secured at several levels. This includes at the first level stimulation of receptors coupled to heterotrimeric G proteins which through stimulation of adenylyl cyclase (AC) forms the second messenger cAMP. Cyclic AMP has several receptors including PKA. PKA is a tetrameric holoenzyme consisting of a regulatory (R) subunit dimer and two catalytic (C) subunits. The R subunit is the receptor for cAMP and compartmentalizes cAMP signals through binding to cell and tissue-specifically expressed A kinase anchoring proteins (AKAPs). The current dogma tells that in the presence of cAMP, PKA dissociates into an R subunit dimer and two C subunits which are free to phosphorylate relevant substrates in the cytosol and nucleus. The release of the C subunit has raised the question how specificity of the cAMP and PKA signaling pathway is maintained when the C subunit no longer is attached to the R subunit-AKAP complex. An increasing body of evidence points toward a regulatory role of the cAMP and PKA signaling pathway by targeting the C subunits to various C subunit binding proteins in the cytosol and nucleus. Moreover, recent identification of isoform specific amino acid sequences, motifs and three dimensional structures have together provided new insight into how PKA at the level of the C subunit may act in a highly isoform-specific fashion. Here we discuss recent understanding of specificity of the cAMP and PKA signaling pathway based on C subunit subcellular targeting as well as evolution of the C subunit structure that may contribute to the dynamic regulation of C subunit activity.
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Affiliation(s)
- Kristoffer Søberg
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Bjørn Steen Skålhegg
- Section for Molecular Nutrition, University of Oslo, Oslo, Norway
- *Correspondence: Bjørn Steen Skålhegg
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18
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Moen LV, Sener Z, Volchenkov R, Svarstad AC, Eriksen AM, Holen HL, Skålhegg BS. Ablation of the Cβ2 subunit of PKA in immune cells leads to increased susceptibility to systemic inflammation in mice. Eur J Immunol 2017; 47:1880-1889. [PMID: 28837222 DOI: 10.1002/eji.201646809] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 06/30/2017] [Accepted: 08/14/2017] [Indexed: 11/06/2022]
Abstract
Protein kinase A (PKA) is a holoenzyme composed of a regulatory subunit dimer and two catalytic subunits and regulates numerous cellular functions including immune cell activity. There are two major catalytic subunit genes, PRKACA and PRKACB encoding the catalytic subunits Cα and Cβ. The PRKACB gene encodes several splice variants including Cβ2, which is enriched in T-, B- and natural killer cells. Cβ2 is significantly larger (46 kDa) than any other C splice variant. In this study we characterized mice ablated for the Cβ2 protein demonstrating a significantly reduced cAMP-induced catalytic activity of PKA in the spleenocytes, lymphocytes and thymocytes. We also observed a significantly increased number of CD62L-expressing CD4+ and CD8+ T cells in LNs, accompanied by increased susceptibility to systemic inflammation by the Cβ2 ablated mice. The latter was reflected in an elevated sensitivity to collagen-induced arthritis (CIA), as well as higher concentration of TNF-α and lower concentration of IL-10 in response to LPS challenges. We suggest a role of Cβ2 in regulating innate as well as adaptive immune sensitivity in vivo.
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Affiliation(s)
- Line Victoria Moen
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Zeynep Sener
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Roman Volchenkov
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Rheumatech AS, Oslo, Norway
| | - Anja Camilla Svarstad
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Aud Marit Eriksen
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | | | - Bjørn S Skålhegg
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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19
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Evolution of the cAMP-dependent protein kinase (PKA) catalytic subunit isoforms. PLoS One 2017; 12:e0181091. [PMID: 28742821 PMCID: PMC5526564 DOI: 10.1371/journal.pone.0181091] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 06/25/2017] [Indexed: 01/16/2023] Open
Abstract
The 3’,5’-cyclic adenosine monophosphate (cAMP)-dependent protein kinase, or protein kinase A (PKA), pathway is one of the most versatile and best studied signaling pathways in eukaryotic cells. The two paralogous PKA catalytic subunits Cα and Cβ, encoded by the genes PRKACA and PRKACB, respectively, are among the best understood model kinases in signal transduction research. In this work, we explore and elucidate the evolution of the alternative 5’ exons and the splicing pattern giving rise to the numerous PKA catalytic subunit isoforms. In addition to the universally conserved Cα1/Cβ1 isoforms, we find kinase variants with short N-termini in all main vertebrate classes, including the sperm-specific Cα2 isoform found to be conserved in all mammals. We also describe, for the first time, a PKA Cα isoform with a long N-terminus, paralogous to the PKA Cβ2 N-terminus. An analysis of isoform-specific variation highlights residues and motifs that are likely to be of functional importance.
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20
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Tillo SE, Xiong WH, Takahashi M, Miao S, Andrade AL, Fortin DA, Yang G, Qin M, Smoody BF, Stork PJS, Zhong H. Liberated PKA Catalytic Subunits Associate with the Membrane via Myristoylation to Preferentially Phosphorylate Membrane Substrates. Cell Rep 2017; 19:617-629. [PMID: 28423323 DOI: 10.1016/j.celrep.2017.03.070] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 12/20/2016] [Accepted: 03/23/2017] [Indexed: 10/19/2022] Open
Abstract
Protein kinase A (PKA) has diverse functions in neurons. At rest, the subcellular localization of PKA is controlled by A-kinase anchoring proteins (AKAPs). However, the dynamics of PKA upon activation remain poorly understood. Here, we report that elevation of cyclic AMP (cAMP) in neuronal dendrites causes a significant percentage of the PKA catalytic subunit (PKA-C) molecules to be released from the regulatory subunit (PKA-R). Liberated PKA-C becomes associated with the membrane via N-terminal myristoylation. This membrane association does not require the interaction between PKA-R and AKAPs. It slows the mobility of PKA-C and enriches kinase activity on the membrane. Membrane-residing PKA substrates are preferentially phosphorylated compared to cytosolic substrates. Finally, the myristoylation of PKA-C is critical for normal synaptic function and plasticity. We propose that activation-dependent association of PKA-C renders the membrane a unique PKA-signaling compartment. Constrained mobility of PKA-C may synergize with AKAP anchoring to determine specific PKA function in neurons.
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Affiliation(s)
- Shane E Tillo
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Wei-Hong Xiong
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Maho Takahashi
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Sheng Miao
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Adriana L Andrade
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Dale A Fortin
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Guang Yang
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Maozhen Qin
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Barbara F Smoody
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Philip J S Stork
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Haining Zhong
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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21
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Yang H, Yang L. Targeting cAMP/PKA pathway for glycemic control and type 2 diabetes therapy. J Mol Endocrinol 2016; 57:R93-R108. [PMID: 27194812 DOI: 10.1530/jme-15-0316] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/18/2016] [Indexed: 12/11/2022]
Abstract
In mammals, cyclic adenosine monophosphate (cAMP) is an intracellular second messenger that is usually elicited by binding of hormones and neurotransmitters to G protein-coupled receptors (GPCRs). cAMP exerts many of its physiological effects by activating cAMP-dependent protein kinase (PKA), which in turn phosphorylates and regulates the functions of downstream protein targets including ion channels, enzymes, and transcription factors. cAMP/PKA signaling pathway regulates glucose homeostasis at multiple levels including insulin and glucagon secretion, glucose uptake, glycogen synthesis and breakdown, gluconeogenesis, and neural control of glucose homeostasis. This review summarizes recent genetic and pharmacological studies concerning the regulation of glucose homeostasis by cAMP/PKA in pancreas, liver, skeletal muscle, adipose tissues, and brain. We also discuss the strategies for targeting cAMP/PKA pathway for research and potential therapeutic treatment of type 2 diabetes mellitus (T2D).
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Affiliation(s)
- Haihua Yang
- Division of EndocrinologyZhengzhou Children's Hospital, Zhengzhou, Henan, China
| | - Linghai Yang
- Department of PharmacologyUniversity of Washington, Seattle, Washington, USA
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22
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Niyitegeka JMV, Bastidas AC, Newman RH, Taylor SS, Ongeri EM. Isoform-specific interactions between meprin metalloproteases and the catalytic subunit of protein kinase A: significance in acute and chronic kidney injury. Am J Physiol Renal Physiol 2014; 308:F56-68. [PMID: 25354939 DOI: 10.1152/ajprenal.00167.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Meprin metalloproteases are abundantly expressed in the brush-border membranes of kidney proximal tubules. Meprins are implicated in ischemia-reperfusion (IR)-induced renal injury and diabetic nephropathy. The protein kinase A (PKA) signaling pathway modulates extracellular matrix metabolism in diabetic kidneys. The present study evaluated isoform-specific interactions between the catalytic subunit of PKA (PKA C) and meprins. To this end, cytosolic-enriched kidney proteins from meprin αβ double knockout mice, and purified forms of recombinant mouse PKA Cα, Cβ1, and Cβ2, were incubated with activated forms of either homomeric meprin A or meprin B. The cleaved protein products were subjected to SDS-PAGE and analyzed by Coomassie staining and Western blot analysis. While meprin A only cleaved PKA Cβ1, meprin B cleaved all three PKA C isoforms. Analysis of the proteolytic fragments by mass spectrometry revealed that meprin A and B cleave the PKA C isoforms at defined sites, resulting in unique cleavage products. Michaelis-Menten enzyme kinetics demonstrated that meprin B-mediated cleavage of PKA Cα occurs at a rate consistent with that of other physiologically relevant meprin substrates. Meprin cleavage decreased the kinase activity of PKA Cα, Cβ1, and Cβ2. PKA C levels were higher in diabetic kidneys, with evidence of in vivo fragmentation in wild-type diabetic kidneys. Confocal microscopy showed localization of meprin A in the glomeruli of diabetic kidneys. At 3 h post-IR, PKA C levels in proximal tubules decreased compared with distal tubules, which lack meprins. These data suggest that meprins may impact kidney injury, in part, via modulation of PKA signaling pathways.
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Affiliation(s)
| | - Adam C Bastidas
- Department of Pharmacology, University of California, San Diego, California; and
| | - Robert H Newman
- Department of Biology, North Carolina A&T State University, Greensboro, North Carolina
| | - Susan S Taylor
- Department of Pharmacology, University of California, San Diego, California; and Howard Hughes Medical Institute, University of California, San Diego, California
| | - Elimelda Moige Ongeri
- Department of Biology, North Carolina A&T State University, Greensboro, North Carolina;
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23
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London E, Nesterova M, Sinaii N, Szarek E, Chanturiya T, Mastroyannis SA, Gavrilova O, Stratakis CA. Differentially regulated protein kinase A (PKA) activity in adipose tissue and liver is associated with resistance to diet-induced obesity and glucose intolerance in mice that lack PKA regulatory subunit type IIα. Endocrinology 2014; 155:3397-408. [PMID: 24914943 PMCID: PMC4138573 DOI: 10.1210/en.2014-1122] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The cAMP-dependent protein kinase A (PKA) signaling system is widely expressed and has a central role in regulating cellular metabolism in all organ systems affected by obesity. PKA has four regulatory (RIα, RIIα, RIβ, RIIβ) and four catalytic (Cα, Cβ, Cγ, Prkx) subunit isoforms that have tissue-specific expression profiles. In mice, knockout (KO) of RIIβ, the primary PKA regulatory subunit in adipose tissue or knockout of the catalytic subunit Cβ resulted in a lean phenotype that resists diet-induced obesity and associated metabolic complications. Here we report that the disruption of the ubiquitously expressed PKA RIIα subunit in mice (RIIαKO) confers resistance to diet-induced obesity, glucose intolerance, and hepatic steatosis. After 2-week high-fat diet exposure, RIIαKO mice weighed less than wild-type littermates. Over time this effect was more pronounced in female mice that were also leaner than their wild-type counterparts, regardless of the diet. Decreased intake of a high-fat diet contributed to the attenuated weight gain in RIIαKO mice. Additionally, RIIα deficiency caused differential regulation of PKA in key metabolic organs: cAMP-stimulated PKA activity was decreased in liver and increased in gonadal adipose tissue. We conclude that RIIα represents a potential target for therapeutic interventions in obesity, glucose intolerance, and nonalcoholic fatty liver disease.
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Affiliation(s)
- Edra London
- Section on Endocrinology and Genetics (E.L., M.N., E.S., S.A.M., C.A.S.), Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Biostatistics and Clinical Epidemiology Service (N.S.), CC, National Institutes of Health, Mouse Metabolism Core Laboratory (T.C., O.G.), National Institute of Diabetes and Digestive and Kidney Diseases, and Eunice Kennedy Shriver National Institute of Child Health and Human Development intramural Summer Student Program (S.A.M.), Bethesda, Maryland 20892
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Søberg K, Jahnsen T, Rognes T, Skålhegg BS, Laerdahl JK. Evolutionary paths of the cAMP-dependent protein kinase (PKA) catalytic subunits. PLoS One 2013; 8:e60935. [PMID: 23593352 PMCID: PMC3625193 DOI: 10.1371/journal.pone.0060935] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 03/05/2013] [Indexed: 11/19/2022] Open
Abstract
3',5'-cyclic adenosine monophosphate (cAMP) dependent protein kinase or protein kinase A (PKA) has served as a prototype for the large family of protein kinases that are crucially important for signal transduction in eukaryotic cells. The PKA catalytic subunits Cα and Cβ, encoded by the two genes PRKACA and PRKACB, respectively, are among the best understood and characterized human kinases. Here we have studied the evolution of this gene family in chordates, arthropods, mollusks and other animals employing probabilistic methods and show that Cα and Cβ arose by duplication of an ancestral PKA catalytic subunit in a common ancestor of vertebrates. The two genes have subsequently been duplicated in teleost fishes. The evolution of the PRKACG retroposon in simians was also investigated. Although the degree of sequence conservation in the PKA Cα/Cβ kinase family is exceptionally high, a small set of signature residues defining Cα and Cβ subfamilies were identified. These conserved residues might be important for functions that are unique to the Cα or Cβ clades. This study also provides a good example of a seemingly simple phylogenetic problem which, due to a very high degree of sequence conservation and corresponding weak phylogenetic signals, combined with problematic nonphylogenetic signals, is nontrivial for state-of-the-art probabilistic phylogenetic methods.
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Affiliation(s)
- Kristoffer Søberg
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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25
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Banday AR, Azim S, Hussain MA, Nehar S, Tabish M. Computational prediction and characterisation of ubiquitously expressed new splice variant of Prkaca gene in mouse. Cell Biol Int 2013; 37:687-93. [PMID: 23456795 DOI: 10.1002/cbin.10080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 02/13/2013] [Indexed: 11/11/2022]
Abstract
Prkaca gene of mouse encodes for a cAMP dependent protein kinase catalytic alpha subunit. PKA occurs naturally as a 4-membered structure having two regulatory (R) and two catalytic (C) subunits each encoded by separate gene. Alternatively spliced two transcript variants are known for the Prkaca gene, which encode for two isoforms of PKA C-subunits, namely Cα1 and Cα2. These isoforms arise as a result of alternative splicing of the first coding exon with the internal exons. We have identified a new transcript variant using combinatorial approach of bioinformatics and molecular biology techniques involving RT-PCR, semi-nested PCR and sequencing. The new transcript variant encoding Cα3 isoform has N-terminus that differs from Cα1 and Cα2 isoforms. Cα3 isoform also arise as a result of alternative splicing of first coding exon with the internal exon. Newly identified transcript is expressed ubiquitously in different tissues examined.
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Affiliation(s)
- Abdul Rouf Banday
- Faculty of Life Sciences, Department of Biochemistry, A.M. University, Aligarh 202 002, Uttar Pradesh, India
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26
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Structural diversity of the cAMP-dependent protein kinase regulatory subunit in Caenorhabditis elegans. Cell Signal 2012; 25:168-77. [PMID: 22975687 DOI: 10.1016/j.cellsig.2012.09.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/05/2012] [Indexed: 11/23/2022]
Abstract
The cAMP-dependent protein kinase (protein kinase A, PK-A) plays a key role in the control of eukaryotic cellular activity. The enzymology of PK-A in the free-living nematode, Caenorhabditis elegans is deceptively simple. Single genes encode the catalytic (C) subunit (kin-1), the regulatory (R) subunit (kin-2) and an A-kinase anchor protein (AKAP) (aka-1); nonetheless, PK-A is able to facilitate a comprehensive array of cAMP-mediated processes in this model multicellular organism. We have previously demonstrated that, in C. elegans, as many as 12 different isoforms of the C-subunit arise as a consequence of alternative splicing strategies. Here, we report the occurrence of transcripts encoding novel isoforms of the PK-A R-subunit in C. elegans. In place of exons 1 and 2, these transcripts include coding sequences from novel B or Q exons directly linked to exon 3, thereby generating isoforms with novel N-termini. R-subunits containing an exon B-encoded N-terminal polypeptide sequence were detected in extracts prepared from mixed populations of C. elegans. Of note is the observation that R-subunit isoforms containing exon B- or exon Q-encoded polypeptide sequences lack the dimerisation/docking domains conventionally seen in R-subunits. This means that they are unlikely to participate in the formation of tetrameric PK-A holoenzymes and, additionally, they are unlikely to interact with AKAP(s). It is therefore possible that, in C. elegans, in addition to tetrameric (R(2)C(2)) PK-A holoenzymes, there is also a sub-population of dimeric (RC) PK-A enzymes that are not tethered by AKAPs. Furthermore, inspection of the N-terminal sequence encoded by exon B suggests that this isoform is a likely target for N-myristoylation. Although unusual, a number of similarly N-myristoylatable R-subunits, from a range of different species, are present in the databases, suggesting that this may be a more generally observed feature of R-subunit structure. The occurrence of R-subunit isoforms, without dimerisation/docking domains (with or without N-myristoylatable N-termini) in other species would suggest that the control of PK-A activity may be more complex than hitherto thought.
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Identification and characterization of novel mutations in the human gene encoding the catalytic subunit Calpha of protein kinase A (PKA). PLoS One 2012; 7:e34838. [PMID: 22514673 PMCID: PMC3325940 DOI: 10.1371/journal.pone.0034838] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 03/06/2012] [Indexed: 01/11/2023] Open
Abstract
The genes PRKACA and PRKACB encode the principal catalytic (C) subunits of protein kinase A (PKA) Cα and Cβ, respectively. Cα is expressed in all eukaryotic tissues examined and studies of Cα knockout mice demonstrate a crucial role for Cα in normal physiology. We have sequenced exon 2 through 10 of PRKACA from the genome of 498 Norwegian donors and extracted information about PRKACA mutations from public databases. We identified four interesting nonsynonymous point mutations, Arg45Gln, Ser109Pro, Gly186Val, and Ser263Cys, in the Cα1 splice variant of the kinase. Cα variants harboring the different amino acid mutations were analyzed for kinase activity and regulatory (R) subunit binding. Whereas mutation of residues 45 and 263 did not alter catalytic activity or R subunit binding, mutation of Ser(109) significantly reduced kinase activity while R subunit binding was unaltered. Mutation of Cα Gly(186) completely abrogated kinase activity and PKA type I but not type II holoenzyme formation. Gly(186) is located in the highly conserved DFG motif of Cα and mutation of this residue to Val was predicted to result in loss of binding of ATP and Mg(2+), which may explain the kinetic inactivity. We hypothesize that individuals born with mutations of Ser(109) or Gly(186) may be faced with abnormal development and possibly severe disease.
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Banday AR, Azim S, Tabish M. Identification and expression analysis of three novel splice variants of protein kinase A catalytic β subunit gene in the mouse using combinatorial in silico and molecular biology approaches. FEBS J 2012; 279:572-85. [DOI: 10.1111/j.1742-4658.2011.08446.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Vetter MM, Zenn HM, Méndez E, van den Boom H, Herberg FW, Skålhegg BS. The testis-specific Cα2 subunit of PKA is kinetically indistinguishable from the common Cα1 subunit of PKA. BMC BIOCHEMISTRY 2011; 12:40. [PMID: 21812984 PMCID: PMC3163529 DOI: 10.1186/1471-2091-12-40] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Accepted: 08/03/2011] [Indexed: 11/22/2022]
Abstract
Background The two variants of the α-form of the catalytic (C) subunit of protein kinase A (PKA), designated Cα1 and Cα2, are encoded by the PRKACA gene. Whereas Cα1 is ubiquitous, Cα2 expression is restricted to the sperm cell. Cα1 and Cα2 are encoded with different N-terminal domains. In Cα1 but not Cα2 the N-terminal end introduces three sites for posttranslational modifications which include myristylation at Gly1, Asp-specific deamidation at Asn2 and autophosphorylation at Ser10. Previous reports have implicated specific biological features correlating with these modifications on Cα1. Since Cα2 is not modified in the same way as Cα1 we tested if they have distinct biochemical activities that may be reflected in different biological properties. Results We show that Cα2 interacts with the two major forms of the regulatory subunit (R) of PKA, RI and RII, to form cAMP-sensitive PKAI and PKAII holoenzymes both in vitro and in vivo as is also the case with Cα1. Moreover, using Surface Plasmon Resonance (SPR), we show that the interaction patterns of the physiological inhibitors RI, RII and PKI were comparable for Cα2 and Cα1. This is also the case for their potency to inhibit catalytic activities of Cα2 and Cα1. Conclusion We conclude that the regulatory complexes formed with either Cα1 or Cα2, respectively, are indistinguishable.
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Affiliation(s)
- Maike M Vetter
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Pb 1046 Blindern, Oslo, Norway
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King CC, Sastri M, Chang P, Pennypacker J, Taylor SS. The rate of NF-κB nuclear translocation is regulated by PKA and A kinase interacting protein 1. PLoS One 2011; 6:e18713. [PMID: 21556136 PMCID: PMC3083391 DOI: 10.1371/journal.pone.0018713] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 03/16/2011] [Indexed: 12/22/2022] Open
Abstract
The mechanism of PKAc-dependent NF-κB activation and subsequent translocation into the nucleus is not well defined. Previously, we showed that A kinase interacting protein 1 (AKIP1) was important for binding and retaining PKAc in the nucleus. Since then, other groups have demonstrated that AKIP1 binds the p65 subunit of NF-κB and regulates its transcriptional activity through the phosphorylation at Ser 276 by PKAc. However, little is known about the formation and activation of the PKAc/AKIP1/p65 complex and the rate at which it enters the nucleus. Initially, we found that the AKIP1 isoform (AKIP 1A) simultaneously binds PKAc and p65 in resting and serum starved cells. Using peptide arrays, we refined the region of AKIP 1A binding on PKAc and mapped the non-overlapping regions on AKIP 1A where PKAc and p65 bind. A peptide to the amino-terminus of PKAc (CAT 1-29) was generated to specifically disrupt the interaction between AKIP 1A and PKAc to study nuclear import of the complex. The rate of p65 nuclear translocation was monitored in the presence or absence of overexpressed AKIP 1A and/or (CAT 1-29). Enhanced nuclear translocation of p65 was observed in the presence of overexpressed AKIP1 and/or CAT 1-29 in cells stimulated with TNFα, and this correlated with decreased phosphorylation of serine 276. To determine whether PKAc phosphorylation of p65 in the cytosol regulated nuclear translocation, serine 276 was mutated to alanine or aspartic acid. Accelerated nuclear accumulation of p65 was observed in the alanine mutant, while the aspartic acid mutation displayed slowed nuclear translocation kinetics. In addition, enhanced nuclear translocation of p65 was observed when PKAc was knocked-down by siRNA. Taken together, these results suggest that AKIP 1A acts to scaffold PKAc to NF-κB in the cytosol by protecting the phosphorylation site and thereby regulating the rate of nuclear translocation of p65.
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Affiliation(s)
- Charles C. King
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Mira Sastri
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
| | - Philip Chang
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Juniper Pennypacker
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
| | - Susan S. Taylor
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
- The Howard Hughes Medical Institute, University of California San Diego, La Jolla, California, United States of America
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Cell-type specific expression of a dominant negative PKA mutation in mice. PLoS One 2011; 6:e18772. [PMID: 21533282 PMCID: PMC3075275 DOI: 10.1371/journal.pone.0018772] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 03/18/2011] [Indexed: 11/19/2022] Open
Abstract
We employed the Cre recombinase/loxP system to create a mouse line in which PKA activity can be inhibited in any cell-type that expresses Cre recombinase. The mouse line carries a mutant Prkar1a allele encoding a glycine to aspartate substitution at position 324 in the carboxy-terminal cAMP-binding domain (site B). This mutation produces a dominant negative RIα regulatory subunit (RIαB) and leads to inhibition of PKA activity. Insertion of a loxP-flanked neomycin cassette in the intron preceding the site B mutation prevents expression of the mutant RIαB allele until Cre-mediated excision of the cassette occurs. Embryonic stem cells expressing RIαB demonstrated a reduction in PKA activity and inhibition of cAMP-responsive gene expression. Mice expressing RIαB in hepatocytes exhibited reduced PKA activity, normal fasting induced gene expression, and enhanced glucose disposal. Activation of the RIαB allele in vivo provides a novel system for the analysis of PKA function in physiology.
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Stakkestad Ø, Larsen ACV, Kvissel AK, Eikvar S, Ørstavik S, Skålhegg BS. Protein kinase A type I activates a CRE-element more efficiently than protein kinase A type II regardless of C subunit isoform. BMC BIOCHEMISTRY 2011; 12:7. [PMID: 21303506 PMCID: PMC3060122 DOI: 10.1186/1471-2091-12-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 02/08/2011] [Indexed: 12/16/2022]
Abstract
Background Protein kinase A type I (PKAI) and PKAII are expressed in most of the eukaryotic cells examined. PKA is a major receptor for cAMP and specificity is achieved partly through tissue-dependent expression and subcellular localization of subunits with different biochemical properties. In addition posttranslational modifications help fine tune PKA activity, distribution and interaction in the cell. In spite of this the functional significance of two forms of PKA in one cell has not been fully determined. Here we have tested the ability of PKAI and PKAII formed by expression of the regulatory (R) subunits RIα or RIIα in conjunction with Cα1 or Cβ2 to activate a co-transfected luciferace reporter gene, controlled by the cyclic AMP responsive element-binding protein (CREB) in vivo. Results We show that PKAI when expressed at equal levels as PKAII was significantly (p < 0.01) more efficient in inducing Cre-luciferace activity at saturating concentrations of cAMP. This result was obtained regardless of catalytic subunit identity. Conclusion We suggest that differential effects of PKAI and PKAII in inducing Cre-luciferace activity depend on R and not C subunit identity.
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Affiliation(s)
- Øystein Stakkestad
- Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Sognsvannsveien 9, P,O, Box 1046 Blindern, N- 0316 OSLO, Norway
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Enns LC, Morton JF, Mangalindan RS, McKnight GS, Schwartz MW, Kaeberlein MR, Kennedy BK, Rabinovitch PS, Ladiges WC. Attenuation of age-related metabolic dysfunction in mice with a targeted disruption of the Cbeta subunit of protein kinase A. J Gerontol A Biol Sci Med Sci 2009; 64:1221-31. [PMID: 19776218 PMCID: PMC2773816 DOI: 10.1093/gerona/glp133] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 08/25/2009] [Indexed: 02/02/2023] Open
Abstract
The cyclic adenosine monophosphate-dependent protein kinase A (PKA) pathway helps regulate both cell growth and division, and triglyceride storage and metabolism in response to nutrient status. Studies in yeast show that disruption of this pathway promotes longevity in a manner similar to caloric restriction. Because PKA is highly conserved, it can be studied in mammalian systems. This report describes the metabolic phenotype of mice lacking the PKA catalytic subunit Cbeta. We confirmed that Cbeta has high levels of expression in the brain but also showed moderate levels in liver. Cbeta-null animals had reduced basal PKA activity while appearing overtly normal when fed standard rodent chow. However, the absence of Cbeta protected mice from diet-induced obesity, steatosis, dyslipoproteinemia, and insulin resistance, without any differences in caloric intake or locomotor activity. These findings have relevant pharmacological implications because aging in mammals is characterized by metabolic decline associated with obesity, altered body fat distribution, and insulin resistance.
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A schistosome cAMP-dependent protein kinase catalytic subunit is essential for parasite viability. PLoS Negl Trop Dis 2009; 3:e505. [PMID: 19707280 PMCID: PMC2724707 DOI: 10.1371/journal.pntd.0000505] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 07/23/2009] [Indexed: 01/05/2023] Open
Abstract
Eukaryotes, protozoan, and helminth parasites make extensive use of protein kinases to control cellular functions, suggesting that protein kinases may represent novel targets for the development of anti-parasitic drugs. Because of their central role in intracellular signaling pathways, cyclic nucleotide–dependent kinases such as cAMP-dependent protein kinase (PKA) represent promising new targets for the treatment of parasitic infections and neoplastic disorders. However, the role of these kinases in schistosome biology has not been characterized and the genes encoding schistosome PKAs have not been identified. Here we provide biochemical evidence for the presence of a PKA signaling pathway in adult Schistosoma mansoni and show that PKA activity is required for parasite viability in vitro. We also provide the first full description of a gene that encodes a PKA catalytic subunit in S. mansoni, named SmPKA-C. Finally we demonstrate, through RNA interference, that SmPKA-C contributes to the PKA activity we detected biochemically and that inhibition of SmPKA-C expression in adult schistosomes results in parasite death. Together our data show that SmPKA-C is a critically important gene product and may represent an attractive therapeutic target for the treatment and control of schistosomiasis. Schistosomes are parasitic flatworms that inhabit the circulatory system and are the cause of a debilitating and insidious disease for millions of people worldwide. Like other complex organisms, schistosomes and other parasitic worms regulate their cell biology through extensive use of enzymes called protein kinases that phosphorylate other proteins to alter their function. One such protein kinase, cAMP-dependent protein kinase (PKA), has been proposed as a therapeutic target for the treatment of parasitic infections and cancer. Here we use biochemical techniques to show that schistosome worms possess a functional PKA pathway that is required for survival of the parasites. We also identify a parasite gene that encodes a functional PKA enzyme and show that silencing this gene results in both significant loss of PKA activity in schistosome worms and parasite death. These findings suggest that the gene we have identified is critically important to schistosomes and that its protein product may represent a target for the development of much-needed new drugs to treat schistosome infections.
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Tissue-specific PKA inhibition using a chemical genetic approach and its application to studies on sperm capacitation. Proc Natl Acad Sci U S A 2008; 105:20740-5. [PMID: 19074277 DOI: 10.1073/pnas.0810971105] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Studies on cAMP signaling and protein kinase A (PKA) function in vivo are limited by the lack of highly specific inhibitors that can be used in primary cell culture and whole animals. Previously we reported that a mutation in the ATP binding pocket of a catalytic subunit (Calpha) of PKA confers sensitivity to the pyrazolo[3,4-d]pyrimidine inhibitor, 1NM-PP1. We have now engineered the mouse Pkraca gene such that after Cre-mediated recombination in vivo, the CalphaM120A mutant protein is expressed and the wild-type Calpha is turned off. We demonstrate the utility of this approach by examining the requirement for PKA activity during capacitation of sperm from mice that express CalphaM120A mutant protein. For CalphaM120A sperm, 10 microM of 1NM-PP1 prevented PKA-dependent phosphorylation and the activation of motility that are both rapidly (<90 s) evoked by the HCO(3)(-) anion. A continuous (90 min) inhibition with 10 microM of 1NM-PP1 prevented the protein tyrosine phosphorylation of late-stage capacitation. Delayed application of 1NM-PP1 demonstrated that PKA activity was required for at least the initial 30 min of capacitation to produce subsequent protein tyrosine phosphorylation. Acute application of 1NM-PP1 rapidly slowed the accelerated beat of activated motility but did not affect the established waveform asymmetry of hyperactivated sperm. Our results demonstrate that PKA in CalphaM120A mutant sperm is rapidly and reversibly inhibited by 1NM-PP1 and that this blockade has selective and time-dependent effects on multiple aspects of capacitation. The conditional CalphaM120A-expressing mouse lines will be valuable tools for studying PKA function in vivo.
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36
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Funderud A, Aas-Hanssen K, Aksaas AK, Hafte TT, Corthay A, Munthe LA, Orstavik S, Skålhegg BS. Isoform-specific regulation of immune cell reactivity by the catalytic subunit of protein kinase A (PKA). Cell Signal 2008; 21:274-81. [PMID: 19000925 DOI: 10.1016/j.cellsig.2008.10.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 10/22/2008] [Accepted: 10/22/2008] [Indexed: 10/21/2022]
Abstract
There are two major genes encoding the catalytic subunits of protein kinase A, Calpha and Cbeta. The functional significance of these isoforms is enigmatic. Lymphoid cells of the immune system express both Calpha and Cbeta. In this study we tested the role of Calpha and Cbeta in regulating immune cell reactivity to antigens using mice carrying a targeted disruption of the Calpha and Cbeta gene respectively. Calpha and Cbeta ablation both resulted in a 50% reduction in PKA-specific kinase activity and the level of PKA type I but not PKA type II. Moreover, despite that C subunit ablation did not affect immune cell development and homeostasis, Calpha but not Cbeta ablation augmented expression of the activation marker CD69 on lymphocytes. CD69 induction coincided with immune cell hyperresponsiveness and was associated with reduced sensitivity to cAMP-mediated inhibition of anti-CD3 induced T cell proliferation. Our results imply that Calpha is required for normal immune cell reactivity and demonstrates isoform-specific effects and non-redundant functions of C subunit isoforms expressed in the same cell.
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Affiliation(s)
- Ane Funderud
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Norway
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37
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Oksvold MP, Funderud A, Kvissel AK, Skarpen E, Henanger H, Huitfeldt HS, Skålhegg BS, Ørstavik S. Epidermal growth factor receptor levels are reduced in mice with targeted disruption of the protein kinase A catalytic subunit. BMC Cell Biol 2008; 9:16. [PMID: 18380891 PMCID: PMC2324083 DOI: 10.1186/1471-2121-9-16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 04/01/2008] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Epidermal Growth Factor Receptor (EGFR) is a key target molecule in current treatment of several neoplastic diseases. Hence, in order to develop and improve current drugs targeting EGFR signalling, an accurate understanding of how this signalling pathway is regulated is required. It has recently been demonstrated that inhibition of cAMP-dependent protein kinase (PKA) induces a ligand-independent internalization of EGFR. Cyclic-AMP-dependent protein kinase consists of a regulatory dimer bound to two catalytic subunits. RESULTS We have investigated the effect on EGFR levels after ablating the two catalytic subunits, Calpha and Cbeta in two different models. The first model used targeted disruption of either Calpha or Cbeta in mice whereas the second model used Calpha and Cbeta RNA interference in HeLa cells. In both models we observed a significant reduction of EGFR expression at the protein but not mRNA level. CONCLUSION Our results suggest that PKA may represent a target that when manipulated can maintain EGFR protein levels at the single cell level as well as in intact animals.
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Affiliation(s)
- Morten P Oksvold
- Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Norway
| | - Ane Funderud
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Anne-Katrine Kvissel
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Ellen Skarpen
- Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Norway
| | - Heidi Henanger
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Henrik S Huitfeldt
- Institute of Pathology, Rikshospitalet University Hospital, University of Oslo, Norway
| | - Bjørn S Skålhegg
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
| | - Sigurd Ørstavik
- Institute for Basic Medical Sciences, Department of Nutrition, University of Oslo Medical School, Norway
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Larsen ACV, Kvissel AK, Hafte TT, Avellan CIA, Eikvar S, Rootwelt T, Ørstavik S, Skålhegg BS. Inactive forms of the catalytic subunit of protein kinase A are expressed in the brain of higher primates. FEBS J 2007; 275:250-62. [PMID: 18070107 DOI: 10.1111/j.1742-4658.2007.06195.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is well documented that the beta-gene of the catalytic (C) subunit of protein kinase A encodes a number of splice variants. These splice variants are equipped with a variable N-terminal end encoded by alternative use of several exons located 5' to exon 2 in the human, bovine and mouse Cbeta gene. In the present study, we demonstrate the expression of six novel human Cbeta mRNAs that lack 99 bp due to loss of exon 4. The novel splice variants, designated CbetaDelta4, were identified in low amounts at the mRNA level in NTera2-N cells. We developed a method to detect CbetaDelta4 mRNAs in various cells and demonstrated that these variants were expressed in human and Rhesus monkey brain. Transient expression and characterization of the CbetaDelta4 variants demonstrated that they are catalytically inactive both in vitro against typical protein kinase A substrates such as kemptide and histone, and in vivo against the cAMP-responsive element binding protein. Furthermore, co-expression of CbetaDelta4 with the regulatory subunit (R) followed by kinase activity assay with increasing concentrations of cAMP and immunoprecipitation with extensive washes with cAMP (1 mm) and immunoblotting demonstrated that the CbetaDelta4 variants associate with both RI and RII in a cAMP-independent fashion. Expression of inactive C subunits which associate irreversibly with R may imply that CbetaDelta4 can modulate local cAMP effects in the brain by permanent association with R subunits even at saturating concentrations of cAMP.
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Affiliation(s)
- Anja C V Larsen
- Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Norway
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Bowen LC, Bicknell AV, Tabish M, Clegg RA, Rees HH, Fisher MJ. Expression of multiple isoforms of the cAMP-dependent protein kinase (PK-A) catalytic subunit in the nematode, Caenorhabditis elegans. Cell Signal 2006; 18:2230-7. [PMID: 16806821 DOI: 10.1016/j.cellsig.2006.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Accepted: 05/09/2006] [Indexed: 10/24/2022]
Abstract
The cAMP-dependent protein kinase (protein kinase A, PK-A) plays a central role in the regulation of many aspects of eukaryotic cellular activity. In the free-living nematode, Caenorhabditis elegans, two genes encode PK-A-like catalytic subunits. The kin-1 gene has the potential to generate, through alternative splicing events, a multiplicity of catalytic subunit isoforms; in contrast, the F47F2.1b gene appears to encode just a single authentic catalytic subunit-like protein. Here, we report on the occurrence of, and developmental changes in the expression of, polypeptide products of these genes in both C. elegans and the closely related nematode, C. briggsae. Polypeptides derived from the F47F2.1 gene and its orthologue were detected in mixed stage populations of C. elegans and C. briggsae, respectively. Likewise, a number of polypeptides arising as a result of alternative splicing of transcripts from kin-1, or its orthologue in C. briggsae, were identified in mixed stage populations of nematodes. These isoforms included polypeptides with N-termini encoded by exons N'1 or N'4 and C-termini encoded by exons 7 or N. The expression of isoforms with an N-terminus encoded by the N'1 exon is of significance because the amino acid sequence encoded by this exon encompasses an N-myristoylation motif. Isoform abundance appears to be related to developmental stage. Substantial differences in polypeptide expression profiles can be seen in embryonic and adult nematodes. The functional significance of this PK-A catalytic subunit isoform diversity is discussed.
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Affiliation(s)
- Laura C Bowen
- Cellular Regulation and Signalling Group, School of Biological Sciences, University of Liverpool, L69 7ZB, UK
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Abstract
The cAMP-dependent kinase (PKA) plays a crucial part in long-term memory formation in the honeybee (Apis mellifera). One of the putative substrates of the PKA activity is the cAMP response element binding protein (CREB), a transcription factor in the bZIP protein family. We searched the honeybee genome to characterize genes from the CREB/CREM and the PKA families. We identified two genes that encode regulatory subunits and three genes encode catalytic subunits of PKA. Eight genes code for bZIP proteins, but only one gene was found that encodes a member of the CREB/CREM family. The phylogenetic relationship of these genes was analysed with their Drosophila and human counterparts.
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Affiliation(s)
- D Eisenhardt
- Neurobiology, FB Biology/Chemistry/Pharmacy, Freie Universität Berlin, Berlin, Germany.
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Funderud A, Henanger HH, Hafte TT, Amieux PS, Ørstavik S, Skålhegg BS. Identification, cloning and characterization of a novel 47 kDa murine PKA C subunit homologous to human and bovine Cbeta2. BMC BIOCHEMISTRY 2006; 7:20. [PMID: 16889664 PMCID: PMC1557514 DOI: 10.1186/1471-2091-7-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Accepted: 08/04/2006] [Indexed: 11/24/2022]
Abstract
Background Two main genes encoding the catalytic subunits Cα and Cβ of cyclic AMP dependent protein kinase (PKA) have been identified in all vertebrates examined. The murine, bovine and human Cβ genes encode several splice variants, including the splice variant Cβ2. In mouse Cβ2 has a relative molecular mass of 38 kDa and is only expressed in the brain. In human and bovine Cβ2 has a relative molecular mass of 47 kDa and is mainly expressed in lymphoid tissues. Results We identified a novel 47 kDa splice variant encoded by the mouse Cβ gene that is highly expressed in lymphoid cells. Cloning, expression, and production of a sequence-specific antiserum and characterization of PKA catalytic subunit activities demonstrated the 47 kDa protein to be a catalytically active murine homologue of human and bovine Cβ2. Based on the present results and the existence of a human brain-specifically expressed Cβ splice variant designated Cβ4 that is identical to the former mouse Cβ2 splice variant, the mouse splice variant has now been renamed mouse Cβ4. Conclusion Murine lymphoid tissues express a protein that is a homologue of human and bovine Cβ2. The murine Cβ gene encodes the splice variants Cβ1, Cβ2, Cβ3 and Cβ4, as is the case with the human Cβ gene.
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Affiliation(s)
- Ane Funderud
- Department of Nutrition Research, Institute of Basic Medical Sciences, University of Oslo, PO Box 1046 Blindern, 0317 Oslo, Norway
| | - Heidi H Henanger
- Department of Nutrition Research, Institute of Basic Medical Sciences, University of Oslo, PO Box 1046 Blindern, 0317 Oslo, Norway
| | - Tilahun T Hafte
- Department of Nutrition Research, Institute of Basic Medical Sciences, University of Oslo, PO Box 1046 Blindern, 0317 Oslo, Norway
| | - Paul S Amieux
- Department of Pharmacology, University of Washington School of Medicine, PO Box 357750, Seattle, WA 98195-7750, USA
| | - Sigurd Ørstavik
- Department of Nutrition Research, Institute of Basic Medical Sciences, University of Oslo, PO Box 1046 Blindern, 0317 Oslo, Norway
| | - Bjørn S Skålhegg
- Department of Nutrition Research, Institute of Basic Medical Sciences, University of Oslo, PO Box 1046 Blindern, 0317 Oslo, Norway
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Sastri M, Barraclough DM, Carmichael PT, Taylor SS. A-kinase-interacting protein localizes protein kinase A in the nucleus. Proc Natl Acad Sci U S A 2005; 102:349-54. [PMID: 15630084 PMCID: PMC544310 DOI: 10.1073/pnas.0408608102] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The genetic variability and covalent modifications associated with the amino terminus of the protein kinase A (PKA) catalytic (C) subunit suggest that it may contribute to protein-protein interactions and/or localization. By using a yeast two-hybrid screen, we identified a PKA-interacting protein (AKIP1) that binds to the amino terminus (residues 1-39) of the C subunit of PKA. The interaction was localized to the A helix (residues 14-39) of the C subunit and to the carboxyl terminus of AKIP1. AKIP1 thus defines the amino-terminal A helix of PKA as a protein interaction motif. In normal breast (Hs 578 Bst) and HeLa cells, AKIP1 is present in the nucleus as speckles. A nuclear localization signal (Arg-14 and Arg-15) was identified. Upon stimulation with forskolin, HeLa cells expressing AKIP1 accumulated higher levels of the endogenous C subunit in the nucleus. Deletion of the carboxyl terminus of AKIP1 or overexpression of residues 1-39 of the C subunit abolished nuclear localization of the activated endogenous C subunit. Thus, AKIP1 describes a PKA-interacting protein that can contribute to localization by a mechanism that is distinct from A-kinase anchoring proteins that interact with the regulatory subunits.
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Affiliation(s)
- Mira Sastri
- The Howard Hughes Medical Institute and Departments of Chemistry and Biochemistry and Pharmacology, University of California at San Diego, La Jolla, CA 92093-0654, USA
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43
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Kvissel AK, Ørstavik S, Øistad P, Rootwelt T, Jahnsen T, Skålhegg BS. Induction of Cβ splice variants and formation of novel forms of protein kinase A type II holoenzymes during retinoic acid-induced differentiation of human NT2 cells. Cell Signal 2004; 16:577-87. [PMID: 14751543 DOI: 10.1016/j.cellsig.2003.08.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cyclic AMP (cAMP) and cAMP-dependent protein kinase (PKA) are critical regulators of neuronal differentiation. The expression, levels and activities of PKA subunits were studied prior to and during differentiation of the human neuronal precursor cell line NTera 2 (NT2). Undifferentiated NT2 cells expressed mainly cytoplasmic PKA type I, consisting of the regulatory subunit RIalpha and the catalytic subunit Calpha. Low levels of PKA type II consisting of RIIalpha or RIIbeta associated with Calpha were also detected, mainly in the cytoplasm and in the Golgi-centrosomal area. During retinoic acid-induced differentiation, the RIalpha and RIIalpha expressions remained in the cytoplasm, while we observed a strong upregulation of RIIbeta, located to the whole cytoplasm including neurite extensions. This upregulation coincided with increased PKA-specific activity accompanied by a strong induction of a number of neuronal-specific Cbeta splice variants that together with RIIbeta form novel PKAII holoenzymes. Formation of novel PKAII holoenzymes may imply specific PKA features which may have consequences for the process of neuronal differentiation and nerve cell function.
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Affiliation(s)
- Anne-Katrine Kvissel
- Institute for Nutrition Research, University of Oslo, PO Box 1046 Blindern, Oslo 0317, Norway
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44
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Zhang W, Morris GZ, Beebe SJ. Characterization of the cAMP-dependent protein kinase catalytic subunit Cγ expressed and purified from sf9 cells. Protein Expr Purif 2004; 35:156-69. [PMID: 15039079 DOI: 10.1016/j.pep.2004.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Revised: 01/12/2004] [Indexed: 11/28/2022]
Abstract
The Cgamma and Calpha subunits of the cAMP-dependent protein kinase (PKA) contain 350 amino acids that are highly homologous (83% amino acid sequence), with 91% homology within the catalytic domain (a.a. 40-300). Unlike Cgamma, the Calpha subunit has been readily purified and characterized as a recombinant protein in vitro, in intact cells, and in vivo. This report describes for the first time the expression, purification, and characterization of Cgamma. The expression of active Cgamma was eukaryote-specific, from mammalian and insect cells, but not bacteria. Active recombinant Cgamma was optimally expressed and purified to homogeneity from Sf9 cells with a 273-fold increase in specific activity and a 21% recovery after sequential CM-Sepharose and Sephacryl S-300 chromatography. The specific activity of pure Cgamma was 0.31 and 0.81 U/mg with kemptide and histone as substrates, respectively. Physical characterization showed Cgamma had a lower apparent molecular weight and Stokes radii than Calpha, suggesting differences in tertiary structures. Steady-state kinetics demonstrated that like Calpha and Cbeta, Cgamma phosphorylates substrates requiring basic amino acids at P-3 and P-2. However, Cgamma generally exhibited a lower Km and Vmax than Calpha for peptide substrates tested. Cgamma also exhibited a distinct pseudosubstrate specificity showing inhibition by homogeneous preparations of RIalpha and RIIalpha-subunits, but not by pure recombinant protein kinase inhibitors PKIalpha and PKIbeta, PKA-specific inhibitors. These studies suggest that Cgamma and Calpha exhibit differences in structure and function in vitro, supporting the hypothesis that functionally different C-subunit isozymes could diversify and/or fine-tune cAMP signal transduction downstream of PKA activation.
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Affiliation(s)
- Weiqing Zhang
- Center For Molecular Biology of Oral Diseases, University of Illinois at Chicago College of Dentistry, 801 S. Paulina Street (M/C 860) Chicago, IL 60612, USA
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45
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Engels BM, Schouten TG, van Dullemen J, Gosens I, Vreugdenhil E. Functional differences between two DCLK splice variants. ACTA ACUST UNITED AC 2004; 120:103-14. [PMID: 14741399 DOI: 10.1016/j.molbrainres.2003.10.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Recently, we have cloned two splice variants of the doublecortin-like kinase (DCLK) gene, called DCLK-short-A and -B, both of which encode calcium/calmodulin-dependent protein kinase (CaMK)-like proteins with different C-terminal ends. Using in situ hybridization, we have found that both are highly expressed in limbic structures of the brain and that their expression differs in a number of brain areas. DCLK-short-A is relatively more strongly expressed than DCLK-short-B in the subependymal zone. The DCLK-short-B variant shows stronger expression in the cortex, the ventromedial and dorsomedial hypothalamic nuclei, the arcuate nucleus, the zona incerta and the subincertal nucleus. Also, within the hippocampus, the relative distribution of these two splice variants differs. DCLK-short-B expression compared to DCLK-short-A is highest in the CA1 area. The expression of the A variant is highest in the CA3/CA4 area. Additionally, DCLK-short-B is expressed at a higher level than DCLK-short-A in the substantia nigra and the mammillary nucleus. Both DCLK-short-A and -B were located in the cytoplasm, however DCLK-short-B was also found specifically in growth cone like structures and near the nucleus. Both DCLK-short proteins phosphorylate autocamtide and syntide, two highly specific CaMK substrates. Finally, removal of the C-terminal end of DCLK-short leads to a 10-fold increase of kinase activity, indicating that the different C-termini represent auto-inhibitory domains. Our results indicate that DCLK-short-A and -B control different neuronal processes that overlap with those controlled by CaMKs.
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Affiliation(s)
- Bart M Engels
- Leiden/Amsterdam Center for Drug Research, Division of Medical Pharmacology, University of Leiden, PO Box 9503, 2300 RA, Leiden, The Netherlands
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Higuchi H, Yamashita T, Yoshikawa H, Tohyama M. PKA phosphorylates the p75 receptor and regulates its localization to lipid rafts. EMBO J 2003; 22:1790-800. [PMID: 12682012 PMCID: PMC154469 DOI: 10.1093/emboj/cdg177] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although a large number of studies have been carried out on the diverse effects mediated by the common neurotrophin receptor p75(NTR), little is known about the molecular mechanisms by which p75(NTR) initiates intracellular signal transduction. We identified a variant of the beta catalytic subunit of cAMP-dependent protein kinase (PKACbeta) as a p75(NTR)-interacting protein, which phosphorylates p75(NTR) at Ser304. Intracellular cAMP in cerebellar neurons was accumulated transiently by ligand binding to p75(NTR). Activation of cAMP-PKA is required for translocation of p75(NTR) to lipid rafts, and for biochemical and biological activities of p75(NTR), such as inactivation of Rho and the neurite outgrowth. Proper recruitment of activated p75(NTR) to lipid rafts, structures that represent specialized signaling organelles, is of fundamental importance in determining p75(NTR) bioactivity.
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Affiliation(s)
- Haruhisa Higuchi
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-087, Japan
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Niswender CM, Ishihara RW, Judge LM, Zhang C, Shokat KM, McKnight GS. Protein engineering of protein kinase A catalytic subunits results in the acquisition of novel inhibitor sensitivity. J Biol Chem 2002; 277:28916-22. [PMID: 12034735 DOI: 10.1074/jbc.m203327200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Analysis of the role of specific protein kinases in signal transduction networks has relied heavily on ATP analog inhibitors. Currently used agents, however, often do not distinguish between kinase family members. Genetic approaches can also be used to inactivate a specific kinase, but these techniques do not afford the rapid kinetics possible with pharmacological inhibitors. To circumvent this problem, modification of the structure of a particular protein kinase can be performed to engineer a drug-target interaction of choice. We have used this method to create protein kinase A (PKA) catalytic subunits with modifications that confer sensitivity to novel ATP analog inhibitors. Mutation of methionine 120 to alanine or glycine in either the Calpha or Cbeta subunits of PKA induces sensitivity to a series of C-3 derivatized pyrazolo[3,4-d]pyrimidine-based inhibitors. Modification of threonine 183 enhances this inhibitor sensitivity. The IC(50) values in cell culture of the most broadly effective agent, 1-NM, ranged from 25 to 200 nm depending upon the combination of modified amino acids and were significantly higher than the potencies observed with H-89. Despite their high sequence conservation, Cbeta enzymes with inhibitor-sensitive amino acids at position 120 showed a substantial loss of overall catalytic activity when used to induce reporter gene transcription in transfected cells. Conversion of position 46 (lysine to isoleucine) rescued the ability of position 120 mutated Cbeta enzymes to induce gene transcription. Application of this combined genetic and pharmacological approach should allow analysis of the specific roles of PKA isoforms in cell culture and in vivo.
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Affiliation(s)
- Colleen M Niswender
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7750, USA
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Huang Y, Roelink H, McKnight GS. Protein kinase A deficiency causes axially localized neural tube defects in mice. J Biol Chem 2002; 277:19889-96. [PMID: 11886853 DOI: 10.1074/jbc.m111412200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have studied the function of protein kinase A (PKA) during embryonic development using a PKA-deficient mouse that retains only one functional catalytic subunit allele, either Calpha or Cbeta, of PKA. The reduced PKA activity results in neural tube defects that are specifically localized posterior to the forelimb buds and lead to spina bifida. The affected neural tube has closed appropriately but exhibits an enlarged lumen and abnormal neuroepithelium. Decreased PKA activity causes dorsal expansion of Sonic hedgehog signal response in the thoracic to sacral regions correlating with the regions of morphological abnormalities. Other regions of the neural tube appear normal. The regional sensitivity to changes in PKA activity indicates that downstream signaling pathways differ along the anterior-posterior axis and suggests a functional role for PKA activation in neural tube development.
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Affiliation(s)
- Yongzhao Huang
- Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195, USA
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Ørstavik S, Reinton N, Frengen E, Langeland BT, Jahnsen T, Skålhegg BS. Identification of novel splice variants of the human catalytic subunit Cbeta of cAMP-dependent protein kinase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:5066-73. [PMID: 11589697 DOI: 10.1046/j.0014-2956.2001.02429.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Four different isoforms of the catalytic subunit of cAMP-dependent protein kinase, termed Calpha, Cbeta, Cgamma and PrKX have been identified. Here we demonstrate that the human Cbeta gene encodes six splice variants, designated Cbeta1, Cbeta2, Cbeta3, Cbeta4, Cbeta4ab and Cbeta4abc. The Cbeta splice variants differ in their N-terminal ends due to differential splicing of four different forms of exon 1 designated exon 1-1, 1-2, 1-3, 1-4 and three exons designated a, b and c. All these exons are located upstream of exon 2 in the Cbeta gene. The previously identified human Cbeta variant has been termed Cbeta1, and is similar to the Cbeta isoform identified in the mouse, ox, pig and several other mammals. Human Cbeta2, which is the homologue of bovine Cbeta2, has no homologue in the mouse. Human Cbeta3 and Cbeta4 are homologous to the murine Cbeta3 and Cbeta2 splice variants, whereas human Cbeta4ab and Cbeta4abc represent novel isofoms previously not identified in any other species. At the mRNA level, the Cbeta splice variants reveal tissue specific expression. Cbeta1 was most abundantly expressed in the brain, with low-level expression in several other tissues. The Cbeta3 and Cbeta4 splice variants were uniquely expressed in human brain in contrast to Cbeta2, which was most abundantly expressed in tissues of the immune system, with no detectable expression in brain. We suggest that the various Cbeta splice variants when complexed with regulatory subunits may give rise to novel holoenzymes of protein kinase A that may be important for mediating specific effects of cAMP.
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Affiliation(s)
- S Ørstavik
- Institute of Medical Biochemistry, Faculty of Medicine, University of Oslo, Blindern, N-0316 Oslo, Norway
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Johnson DA, Akamine P, Radzio-Andzelm E, Madhusudan M, Taylor SS. Dynamics of cAMP-dependent protein kinase. Chem Rev 2001; 101:2243-70. [PMID: 11749372 DOI: 10.1021/cr000226k] [Citation(s) in RCA: 317] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D A Johnson
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0654, USA
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