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Omar MH, Byrne DP, Shrestha S, Lakey TM, Lee KS, Lauer SM, Collins KB, Daly LA, Eyers CE, Baird GS, Ong SE, Kannan N, Eyers PA, Scott JD. Discovery of a Cushing's syndrome protein kinase A mutant that biases signaling through type I AKAPs. SCIENCE ADVANCES 2024; 10:eadl1258. [PMID: 38381834 PMCID: PMC10881042 DOI: 10.1126/sciadv.adl1258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 01/18/2024] [Indexed: 02/23/2024]
Abstract
Adrenal Cushing's syndrome is a disease of cortisol hypersecretion often caused by mutations in protein kinase A catalytic subunit (PKAc). Using a personalized medicine screening platform, we discovered a Cushing's driver mutation, PKAc-W196G, in ~20% of patient samples analyzed. Proximity proteomics and photokinetic imaging reveal that PKAcW196G is unexpectedly distinct from other described Cushing's variants, exhibiting retained association with type I regulatory subunits (RI) and their corresponding A kinase anchoring proteins (AKAPs). Molecular dynamics simulations predict that substitution of tryptophan-196 with glycine creates a 653-cubic angstrom cleft between the catalytic core of PKAcW196G and type II regulatory subunits (RII), but only a 395-cubic angstrom cleft with RI. Endocrine measurements show that overexpression of RIα or redistribution of PKAcW196G via AKAP recruitment counteracts stress hormone overproduction. We conclude that a W196G mutation in the kinase catalytic core skews R subunit selectivity and biases AKAP association to drive Cushing's syndrome.
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Affiliation(s)
- Mitchell H. Omar
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Dominic P. Byrne
- Department of Biochemistry, Cell and Systems Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Safal Shrestha
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Tyler M. Lakey
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Kyung-Soon Lee
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Sophia M. Lauer
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Kerrie B. Collins
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Leonard A. Daly
- Centre for Proteome Research, Department of Biochemistry, Cell and Systems Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Claire E. Eyers
- Centre for Proteome Research, Department of Biochemistry, Cell and Systems Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Geoffrey S. Baird
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Shao-En Ong
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Natarajan Kannan
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Patrick A. Eyers
- Department of Biochemistry, Cell and Systems Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - John D. Scott
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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Chrispell JD, Xiong Y, Weiss ER. Grk7 but not Grk1 undergoes cAMP-dependent phosphorylation in zebrafish cone photoreceptors and mediates cone photoresponse recovery to elevated cAMP. J Biol Chem 2022; 298:102636. [PMID: 36273582 PMCID: PMC9692042 DOI: 10.1016/j.jbc.2022.102636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 11/07/2022] Open
Abstract
In the vertebrate retina, phosphorylation of photoactivated visual pigments in rods and cones by G protein-coupled receptor kinases (GRKs) is essential for sustained visual function. Previous in vitro analysis demonstrated that GRK1 and GRK7 are phosphorylated by PKA, resulting in a reduced capacity to phosphorylate rhodopsin. In vivo observations revealed that GRK phosphorylation occurs in the dark and is cAMP dependent. In many vertebrates, including humans and zebrafish, GRK1 is expressed in both rods and cones while GRK7 is expressed only in cones. However, mice express only GRK1 in both rods and cones and lack GRK7. We recently generated a mutation in Grk1 that deletes the phosphorylation site, Ser21. This mutant demonstrated delayed dark adaptation in mouse rods but not in cones in vivo, suggesting GRK1 may serve a different role depending upon the photoreceptor cell type in which it is expressed. Here, zebrafish were selected to evaluate the role of cAMP-dependent GRK phosphorylation in cone photoreceptor recovery. Electroretinogram analyses of larvae treated with forskolin show that elevated intracellular cAMP significantly decreases recovery of the cone photoresponse, which is mediated by Grk7a rather than Grk1b. Using a cone-specific dominant negative PKA transgene, we show for the first time that PKA is required for Grk7a phosphorylation in vivo. Lastly, immunoblot analyses of rod grk1a-/- and cone grk1b-/- zebrafish and Nrl-/- mouse show that cone-expressed Grk1 does not undergo cAMP-dependent phosphorylation in vivo. These results provide a better understanding of the function of Grk phosphorylation relative to cone adaptation and recovery.
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Wolf EW, Howard ZP, Duan L, Tam H, Xu Y, Cyster JG. GPR174 signals via G αs to control a CD86-containing gene expression program in B cells. Proc Natl Acad Sci U S A 2022; 119:e2201794119. [PMID: 35639700 PMCID: PMC9191659 DOI: 10.1073/pnas.2201794119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/14/2022] [Indexed: 11/18/2022] Open
Abstract
GPR174 is abundantly expressed in B and T lymphocytes and has a role in restraining T cell responses, but the function of GPR174 in B cells is less clear. Here we report that upon in vitro culture B cells undergo a spontaneous GPR174-dependent activation process that is associated with marked changes in gene expression, including up-regulation of Cd86, Nr4a1, Ccr7, and phosphodiesterases. B cells lacking Gαs show a block in induction of the GPR174-dependent program. Spontaneous up-regulation of CD86 in cultured B cells is dependent on protein kinase A. Both GPR174- and Gαs-deficient B cells show enhanced survival in culture. In vivo, GPR174 contributes to NUR77 expression in follicular B cells and is needed for establishing a marginal zone compartment of normal size. Treatment of mice with lysophosphatidylserine (lysoPS), a GPR174 ligand, is sufficient to promote CD86 up-regulation by follicular B cells. These findings demonstrate that GPR174 can signal via Gαs to modulate B cell gene expression and show this can occur in vivo in response to lysoPS. Additionally, the findings illuminate a pathway that might be targeted to improve systems for the in vitro study of B cell responses.
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Affiliation(s)
- Elise W. Wolf
- HHMI, University of California, San Francisco, CA 94143
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
| | - Zachary P. Howard
- HHMI, University of California, San Francisco, CA 94143
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
| | - Lihui Duan
- HHMI, University of California, San Francisco, CA 94143
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
| | - Hanson Tam
- HHMI, University of California, San Francisco, CA 94143
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
| | - Ying Xu
- HHMI, University of California, San Francisco, CA 94143
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
| | - Jason G. Cyster
- HHMI, University of California, San Francisco, CA 94143
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
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Jia Y, Marq JB, Bisio H, Jacot D, Mueller C, Yu L, Choudhary J, Brochet M, Soldati-Favre D. Crosstalk between PKA and PKG controls pH-dependent host cell egress of Toxoplasma gondii. EMBO J 2017; 36:3250-3267. [PMID: 29030485 PMCID: PMC5666616 DOI: 10.15252/embj.201796794] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 09/08/2017] [Accepted: 09/12/2017] [Indexed: 12/27/2022] Open
Abstract
Toxoplasma gondii encodes three protein kinase A catalytic (PKAc1-3) and one regulatory (PKAr) subunits to integrate cAMP-dependent signals. Here, we show that inactive PKAc1 is maintained at the parasite pellicle by interacting with acylated PKAr. Either a conditional knockdown of PKAr or the overexpression of PKAc1 blocks parasite division. Conversely, down-regulation of PKAc1 or stabilisation of a dominant-negative PKAr isoform that does not bind cAMP triggers premature parasite egress from infected cells followed by serial invasion attempts leading to host cell lysis. This untimely egress depends on host cell acidification. A phosphoproteome analysis suggested the interplay between cAMP and cGMP signalling as PKAc1 inactivation changes the phosphorylation profile of a putative cGMP-phosphodiesterase. Concordantly, inhibition of the cGMP-dependent protein kinase G (PKG) blocks egress induced by PKAc1 inactivation or environmental acidification, while a cGMP-phosphodiesterase inhibitor circumvents egress repression by PKAc1 or pH neutralisation. This indicates that pH and PKAc1 act as balancing regulators of cGMP metabolism to control egress. These results reveal a crosstalk between PKA and PKG pathways to govern egress in T. gondii.
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Affiliation(s)
- Yonggen Jia
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Hugo Bisio
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Damien Jacot
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Christina Mueller
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Lu Yu
- Proteomic Mass-spectrometry Team, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Jyoti Choudhary
- Proteomic Mass-spectrometry Team, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Mathieu Brochet
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva 4, Switzerland
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Le Stunff C, Tilotta F, Sadoine J, Le Denmat D, Briet C, Motte E, Clauser E, Bougnères P, Chaussain C, Silve C. Knock-In of the Recurrent R368X Mutation of PRKAR1A that Represses cAMP-Dependent Protein Kinase A Activation: A Model of Type 1 Acrodysostosis. J Bone Miner Res 2017; 32:333-346. [PMID: 27589370 DOI: 10.1002/jbmr.2987] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 08/19/2016] [Accepted: 09/01/2016] [Indexed: 12/13/2022]
Abstract
In humans, activating mutations in the PRKAR1A gene cause acrodysostosis 1 (ACRDYS1). These mutations result in a reduction in PKA activation caused by an impaired ability of cAMP to dissociate mutant PRKAR1A from catalytic PKA subunits. Two striking features of this rare developmental disease are renal resistance to PTH and chondrodysplasia resulting from the constitutive inhibition of PTHR1/Gsa/AC/cAMP/PKA signaling. We developed a knock-in of the recurrent ACRDYS1 R368X PRKAR1A mutation in the mouse. No litters were obtained from [R368X]/[+] females (thus no homozygous [R368X]/[R368X] mice). In [R368X]/[+] mice, Western blot analysis confirmed mutant allele heterozygous expression. Growth retardation, peripheral acrodysostosis (including brachydactyly affecting all digits), and facial dysostosis were shown in [R368X]/[+] mice by weight curves and skeletal measurements (μCT scan) as a function of time. [R368X]/[+] male and female mice were similarly affected. Unexpected, however, whole-mount skeletal preparations revealed a striking delay in mineralization in newborn mutant mice, accompanied by a decrease in the height of terminal hypertrophic chondrocyte layer, an increase in the height of columnar proliferative prehypertrophic chondrocyte layer, and changes in the number and spatial arrangement of proliferating cell nuclear antigen (PCNA)-positive chondrocytes. Plasma PTH and basal urinary cAMP were significantly higher in [R368X]/[+] compared to WT mice. PTH injection increased urinary cAMP similarly in [R368X]/[+] and WT mice. PRKACA expression was regulated in a tissue (kidney not bone and liver) manner. This model, the first describing the germline expression of a PRKAR1A mutation causing dominant repression of cAMP-dependent PKA, reproduced the main features of ACRDYS1 in humans. It should help decipher the specificity of the cAMP/PKA signaling pathway, crucial for numerous stimuli. In addition, our results indicate that PRKAR1A, by tempering intracellular cAMP levels, is a molecular switch at the crossroads of signaling pathways regulating chondrocyte proliferation and differentiation. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Catherine Le Stunff
- INSERM U1169, University Paris Sud, Hôpital Bicêtre, Le Kremlin Bicêtre, France
| | - Francoise Tilotta
- EA 2496 Laboratory Orofacial Pathologies, Imagery and Biotherapies, Dental School and Life imaging Platform (PIV), University Paris Descartes Sorbonne Paris Cité, Montrouge, France
| | - Jérémy Sadoine
- EA 2496 Laboratory Orofacial Pathologies, Imagery and Biotherapies, Dental School and Life imaging Platform (PIV), University Paris Descartes Sorbonne Paris Cité, Montrouge, France
| | - Dominique Le Denmat
- EA 2496 Laboratory Orofacial Pathologies, Imagery and Biotherapies, Dental School and Life imaging Platform (PIV), University Paris Descartes Sorbonne Paris Cité, Montrouge, France
| | - Claire Briet
- INSERM U1169, University Paris Sud, Hôpital Bicêtre, Le Kremlin Bicêtre, France
| | - Emmanuelle Motte
- INSERM U1169, University Paris Sud, Hôpital Bicêtre, Le Kremlin Bicêtre, France
| | - Eric Clauser
- INSERM U970, University Paris Descartes, Paris Centre de Recherche Cardiovasculaire (PARCC), Paris, France
| | - Pierre Bougnères
- INSERM U1169, University Paris Sud, Hôpital Bicêtre, Le Kremlin Bicêtre, France
| | - Catherine Chaussain
- EA 2496 Laboratory Orofacial Pathologies, Imagery and Biotherapies, Dental School and Life imaging Platform (PIV), University Paris Descartes Sorbonne Paris Cité, Montrouge, France.,Assistance Publique-Hôpitaux de Paris (AP-HP) Odontology Department Bretonneau, Louis Mourier, Hôpitaux Universitaires Paris Nord Val de Seine, Paris, France.,Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium and Filière de Santé Maladies Rares OSCAR, AP-HP, Paris, France
| | - Caroline Silve
- INSERM U1169, University Paris Sud, Hôpital Bicêtre, Le Kremlin Bicêtre, France.,Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium and Filière de Santé Maladies Rares OSCAR, AP-HP, Paris, France.,Service de Biochimie et Génétique Moléculaire, Hôpital Cochin, AP-HP, Paris, France
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6
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Rajan S, Dickson LM, Mathew E, Orr CMO, Ellenbroek JH, Philipson LH, Wicksteed B. Chronic hyperglycemia downregulates GLP-1 receptor signaling in pancreatic β-cells via protein kinase A. Mol Metab 2015; 4:265-76. [PMID: 25830090 PMCID: PMC4354925 DOI: 10.1016/j.molmet.2015.01.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 01/21/2015] [Accepted: 01/26/2015] [Indexed: 02/07/2023] Open
Abstract
Objective Glucagon-like peptide 1 (GLP-1) enhances insulin secretion and protects β-cell mass. Diabetes therapies targeting the GLP-1 receptor (GLP-1R), expressed in numerous tissues, have diminished dose-response in patients with type 2 diabetes compared with healthy human controls. The aim of this study was to determine the mechanistic causes underlying the reduced efficacy of GLP-1R ligands. Methods Using primary mouse islets and the β-cell line MIN6, outcomes downstream of the GLP-1R were analyzed: Insulin secretion; phosphorylation of the cAMP-response element binding protein (CREB); cAMP responses. Signaling systems were studied by immunoblotting and qRT-PCR, and PKA activity was assayed. Cell surface localization of the GLP-1R was studied by confocal microscopy using a fluorescein-tagged exendin-4 and GFP-tagged GLP-1R. Results Rodent β-cells chronically exposed to high glucose had diminished responses to GLP-1R agonists including: diminished insulin secretory response; reduced phosphorylation of (CREB); impaired cAMP response, attributable to chronically increased cAMP levels. GLP-1R signaling systems were affected by hyperglycemia with increased expression of mRNAs encoding the inducible cAMP early repressor (ICER) and adenylyl cyclase 8, reduced PKA activity due to increased expression of the PKA-RIα subunit, reduced GLP-1R mRNA expression and loss of GLP-1R from the cell surface. To specifically examine the loss of GLP-1R from the plasma membrane a GLP-1R-GFP fusion protein was employed to visualize subcellular localization. Under low glucose conditions or when PKA activity was inhibited, GLP-1R-GFP was found at the plasma membrane. Conversely high glucose, expression of a constitutively active PKA subunit, or exposure to exendin-4 or forskolin led to GLP-1R-GFP internalization. Mutation of serine residue 301 of the GLP-1R abolished the glucose-dependent loss of the receptor from the plasma membrane. This was associated with a loss of an interaction between the receptor and the small ubiquitin-related modifier (SUMO), an interaction that was found to be necessary for internalization of the receptor. Conclusions These data show that glucose acting, at least in part, via PKA leads to the loss of the GLP-1R from the cell surface and an impairment of GLP-1R signaling, which may underlie the reduced clinical efficacy of GLP-1R based therapies in individuals with poorly controlled hyperglycemia.
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Affiliation(s)
- Sindhu Rajan
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA
| | - Lorna M Dickson
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA
| | - Elizabeth Mathew
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA
| | - Caitlin M O Orr
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA ; Committee on Molecular Metabolism and Nutrition, The University of Chicago, USA
| | - Johanne H Ellenbroek
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA
| | - Louis H Philipson
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA ; Committee on Molecular Metabolism and Nutrition, The University of Chicago, USA
| | - Barton Wicksteed
- Kovler Diabetes Center, The University of Chicago, USA ; Department of Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, USA ; Committee on Molecular Metabolism and Nutrition, The University of Chicago, USA
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Gilbert ML, Yang L, Su T, McKnight GS. Expression of a dominant negative PKA mutation in the kidney elicits a diabetes insipidus phenotype. Am J Physiol Renal Physiol 2015; 308:F627-38. [PMID: 25587115 DOI: 10.1152/ajprenal.00222.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
PKA plays a critical role in water excretion through regulation of the production and action of the antidiuretic hormone arginine vasopressin (AVP). The AVP prohormone is produced in the hypothalamus, where its transcription is regulated by cAMP. Once released into the circulation, AVP stimulates antidiuresis through activation of vasopressin 2 receptors in renal principal cells. Vasopressin 2 receptor activation increases cAMP and activates PKA, which, in turn, phosphorylates aquaporin (AQP)2, triggering apical membrane accumulation, increased collecting duct permeability, and water reabsorption. We used single-minded homolog 1 (Sim1)-Cre recombinase-mediated expression of a dominant negative PKA regulatory subunit (RIαB) to disrupt kinase activity in vivo and assess the role of PKA in fluid homeostasis. RIαB expression gave rise to marked polydipsia and polyuria; however, neither hypothalamic Avp mRNA expression nor urinary AVP levels were attenuated, indicating a primary physiological effect on the kidney. RIαB mice displayed a marked deficit in urinary concentrating ability and greatly reduced levels of AQP2 and phospho-AQP2. Dehydration induced Aqp2 mRNA in the kidney of both control and RIαB-expressing mice, but AQP2 protein levels were still reduced in RIαB-expressing mutants, and mice were unable to fully concentrate their urine and conserve water. We conclude that partial PKA inhibition in the kidney leads to posttranslational effects that reduce AQP2 protein levels and interfere with apical membrane localization. These findings demonstrate a distinct physiological role for PKA signaling in both short- and long-term regulation of AQP2 and characterize a novel mouse model of diabetes insipidus.
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Affiliation(s)
- Merle L Gilbert
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Linghai Yang
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Thomas Su
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - G Stanley McKnight
- Department of Pharmacology, University of Washington, Seattle, Washington
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Nguyen E, Gausdal G, Varennes J, Pendino F, Lanotte M, Døskeland SO, Ségal-Bendirdjian E. Activation of both protein kinase A (PKA) type I and PKA type II isozymes is required for retinoid-induced maturation of acute promyelocytic leukemia cells. Mol Pharmacol 2013; 83:1057-65. [PMID: 23455313 DOI: 10.1124/mol.112.081034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute promyelocytic leukemia (APL) is characterized by granulopoietic differentiation arrest at the promyelocytic stage. In most cases, this defect can be overcome by treatment with all-trans-retinoic acid (ATRA), leading to complete clinical remission. Cyclic AMP signaling has a key role in retinoid treatment efficacy: it enhances ATRA-induced maturation in ATRA-sensitive APL cells (including NB4 cells) and restores it in some ATRA-resistant cells (including NB4-LR1 cells). We show that the two cell types express identical levels of the Cα catalytic subunit and comparable global cAMP-dependent protein kinase A (PKA) enzyme activity. However, the maturation-resistant NB4-LR1 cells have a PKA isozyme switch: compared with the NB4 cells, they have decreased content of the juxtanuclearly located PKA regulatory subunit IIα and PKA regulatory subunit IIβ, and a compensatory increase of the generally cytoplasmically distributed PKA-RIα. Furthermore, the PKA regulatory subunit II exists mainly in the less cAMP-responsive nonautophosphorylated state in the NB4-LR1 cells. By the use of isozyme-specific cAMP analog pairs, we show that both PKA-I and PKA-II must be activated to achieve maturation in NB4-LR1 as well as NB4 cells. Therefore, special attention should be paid to activating not only PKA-I but also PKA-II in attempts to enhance ATRA-induced APL maturation in a clinical setting.
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Affiliation(s)
- Eric Nguyen
- Institut National de la Santé et de Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR)-S 1007, Homeostasis and Cancer, Paris, France
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Thompson IR, Ciccone NA, Xu S, Zaytseva S, Carroll RS, Kaiser UB. GnRH pulse frequency-dependent stimulation of FSHβ transcription is mediated via activation of PKA and CREB. Mol Endocrinol 2013; 27:606-18. [PMID: 23393127 DOI: 10.1210/me.2012-1281] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Expression of pituitary FSH and LH, under the control of pulsatile GnRH, is essential for fertility. cAMP response element-binding protein (CREB) has been implicated in the regulation of FSHβ gene expression, but the molecular mechanisms by which pulsatile GnRH regulates CREB activation remain poorly understood. We hypothesized that CREB is activated by a distinct signaling pathway in response to pulsatile GnRH in a frequency-dependent manner to dictate the FSHβ transcriptional response. GnRH stimulation of CREB phosphorylation (pCREB) in the gonadotrope-derived LβT2 cell line was attenuated by a protein kinase A (PKA) inhibitor, H89. A dominant negative PKA (DNPKA) reduced GnRH-stimulated pCREB and markedly decreased GnRH stimulation of FSHβ mRNA and FSHβLUC activity, but had little effect on LHβLUC activity, indicating relative specificity of this pathway. In perifusion studies, FSHβ mRNA levels and FSHβLUC activities were increased by pulsatile GnRH, with significantly greater increases at low compared with high pulse frequencies. DNPKA markedly reduced these GnRH-stimulated FSHβ responses at both low and high pulse frequencies. Correlating with FSHβ activation, both PKA activity and levels of pCREB were increased to a greater extent by low compared with high GnRH pulse frequencies, and the induction of pCREB was also attenuated by overexpression of DNPKA at both low and high pulse frequencies. Taken together, these data indicate that a PKA-mediated signaling pathway mediates GnRH activation of CREB at low-pulse frequencies, playing a significant role in the decoding of the hypothalamic GnRH signal to result in frequency-dependent FSHβ activation.
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Affiliation(s)
- Iain R Thompson
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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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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Greene EL, Horvath AD, Nesterova M, Giatzakis C, Bossis I, Stratakis CA. In vitro functional studies of naturally occurring pathogenic PRKAR1A mutations that are not subject to nonsense mRNA decay. Hum Mutat 2008; 29:633-9. [PMID: 18241045 DOI: 10.1002/humu.20688] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Patients presenting with primary pigmented nodular adrenocortical disease (PPNAD), Carney complex (CNC), or sporadic tumors were previously found to carry germline mutations in the human type Ialpha regulatory subunit (RIalpha) of adenosine 3',5'-cyclic monophosphate (cyclic AMP [cAMP])-dependent protein kinase (PKA; PRKAR1A). Although about 90% of disease-causing PRKAR1A mutations lead to premature stop codon generation and subsequent degradation of the mutant message by nonsense-mediated mRNA decay (NMD), here we describe seven PRKAR1A mutations whose mRNAs do not seem to undergo NMD and instead result in an expressed mutant RIalpha protein. The expressed mutations (p.Ser9Asn, p.Glu60_Lys116del [Delta-exon 3], p.Arg74Cys, p.Arg146Ser, p.Asp183Tyr, p.Ala213Asp, and p.Gly289Trp) were spread over all the functional RIalpha domains, and all of them exhibited increased PKA activity, which we attribute to decreased binding to cAMP and/or the catalytic subunit. Our data further corroborate the previous finding that altered PRKAR1A function, not only haploinsufficiency, is enough to elevate PKA activity which is apparently associated with tumorigenesis in tissues affected by CNC. In some cases, as with the Delta-exon 3 mutation, we may even conclude that the presence of a mutant PRKAR1A protein may be more harmful than allelic loss.
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Affiliation(s)
- Elizabeth L Greene
- Section on Endocrinology & Genetics, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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12
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Howe DG, Clarke CM, Yan H, Willis BS, Schneider DA, McKnight GS, Kapur RP. Inhibition of protein kinase A in murine enteric neurons causes lethal intestinal pseudo-obstruction. ACTA ACUST UNITED AC 2006; 66:256-72. [PMID: 16329126 DOI: 10.1002/neu.20217] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A number of in vitro studies suggest that many important developmental and functional events in the enteric nervous system are regulated by the intracellular signaling enzyme cAMP protein kinase A (PKA). To evaluate the in vivo significance of these observations, a Cre-inducible, dominant-negative, mutant regulatory subunit (RIalphaB) of PKA was activated in enteric neurons by either a Proteolipid protein-Cre transgene or a Hox11L1-Cre "knock-in" allele. In both models, RIalphaB activation resulted consistently in profound distension of the proximal small intestine within 2 weeks after birth. Intestinal transit of radio-opaque tracers was severely retarded in the double-transgenic animals, which died shortly after weaning. In the enteric nervous system, recombination was restricted to neurons as demonstrated by histochemical analysis and confocal microscopic colocalization of a Cre recombinase-dependent reporter gene with the neuronal marker Hu(C/D), in contrast with the glial marker S100. Histochemical analysis of beta-galactosidase expression and acetylcholinesterase activity, as well as neuronal counts, demonstrated that intestinal dysmotility was not associated with obvious malformation of the myenteric plexus. However, inhibition of PKA activity in enteric neurons disrupted the major motor complexes of isolated intestinal segments in vitro. These results provide strong evidence that PKA activity plays a critical role in enteric neurotransmission in vivo, and highlight neuronal PKA or related signaling molecules as potential therapeutic targets in gastrointestinal motility disorders.
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Affiliation(s)
- Douglas G Howe
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7750, USA
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13
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Leboulle G, Müller U. Synergistic activation of insect cAMP-dependent protein kinase A (type II) by cyclicAMP and cyclicGMP. FEBS Lett 2004; 576:216-20. [PMID: 15474040 DOI: 10.1016/j.febslet.2004.08.079] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Revised: 08/06/2004] [Accepted: 08/17/2004] [Indexed: 11/19/2022]
Abstract
The high cGMP sensitivity of cAMP-dependent protein kinase A (type II) (PKAII) from invertebrates led to the hypothesis that cGMP directly activates PKAII under physiological conditions. We tested this idea using PKAII holoenzyme purified from the honeybee brain in an assay with short stimulation times. In the presence of very low cAMP concentrations, we found a synergistic increase in PKAII activation by physiological cGMP concentrations. Cloning honeybee regulatory subunit RII and phylogenetic comparison of the two cyclic nucleotide-binding sites of RII reveal a high relation of domain A of insect RII with cGMP-binding domains of cGMP-dependent protein kinases.
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Affiliation(s)
- Gérard Leboulle
- Institut für Biologie, Freie Universität Berlin, Neurobiologie Königin-Luise-Strasse 28/30, D-14195 Berlin, Germany.
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14
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Preitner F, Ibberson M, Franklin I, Binnert C, Pende M, Gjinovci A, Hansotia T, Drucker DJ, Wollheim C, Burcelin R, Thorens B. Gluco-incretins control insulin secretion at multiple levels as revealed in mice lacking GLP-1 and GIP receptors. J Clin Invest 2004. [DOI: 10.1172/jci200420518] [Citation(s) in RCA: 191] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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15
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Nguyen PV, Woo NH. Regulation of hippocampal synaptic plasticity by cyclic AMP-dependent protein kinases. Prog Neurobiol 2003; 71:401-37. [PMID: 15013227 DOI: 10.1016/j.pneurobio.2003.12.003] [Citation(s) in RCA: 233] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2003] [Accepted: 12/02/2003] [Indexed: 11/17/2022]
Abstract
Protein kinases critically regulate synaptic plasticity in the mammalian hippocampus. Cyclic-AMP dependent protein kinase (PKA) is a serine-threonine kinase that has been strongly implicated in the expression of specific forms of long-term potentiation (LTP), long-term depression (LTD), and hippocampal long-term memory. We review the roles of PKA in activity-dependent forms of hippocampal synaptic plasticity by highlighting particular themes that have emerged in ongoing research. These include the participation of distinct isoforms of PKA in specific types of synaptic plasticity, modification of the PKA-dependence of LTP by multiple factors such as distinct patterns of imposed activity, environmental enrichment, and genetic manipulation of signalling molecules, and presynaptic versus postsynaptic mechanisms for PKA-dependent LTP. We also discuss many of the substrates that have been implicated as targets for PKA's actions in hippocampal synaptic plasticity, including CREB, protein phosphatases, and glutamatergic receptors. Future prospects for shedding light on the roles of PKA are also described from the perspective of specific aspects of synaptic physiology and brain function that are ripe for investigation using incisive genetic, cell biological, and electrophysiological approaches.
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Affiliation(s)
- P V Nguyen
- Departments of Physiology and Psychiatry, Centre for Neuroscience, University of Alberta School of Medicine, Edmonton, Alta., Canada T6G 2H7.
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16
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Kammer GM. Deficient protein kinase a in systemic lupus erythematosus: a disorder of T lymphocyte signal transduction. Ann N Y Acad Sci 2002; 968:96-105. [PMID: 12119270 DOI: 10.1111/j.1749-6632.2002.tb04329.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Systemic lupus erythematosus (SLE) is an idiopathic autoimmune disease characterized by impaired T lymphocyte immune effector functions. We have identified a disorder of signal transduction in SLE T cells involving the cyclic AMP/protein kinase A (cAMP/PKA) pathway. Cyclic AMP-stimulated PKA-catalyzed protein phosphorylation is markedly diminished owing to profound deficiencies of both type I (PKA-I) and type II (PKA-II) isozyme activities. Deficient PKA-I isozyme is characterized by a significant reduction in the amount of type I regulatory beta subunit (RI beta) steady state mRNA by competitive polymerase chain reaction. This is associated with a 30% decrease in RI alpha protein and a 65% reduction in RI beta protein. Indeed, T cells from approximately 25% of SLE subjects have no detectable RI beta protein. Transient transfection of T cells not expressing RI beta protein with autologous SLE RI beta cDNA bypassed the block in translation, reconstituting PKA activity and augmenting IL-2 production. Of importance was the initial identification of novel RI alpha mRNA mutations characterized by heterogeneous transcript mutations, including deletions, transitions, and transversions. Most mutations are clustered adjacent to GAGAG motifs and CT repeats. By contrast, deficient PKA-II activity is the result of spontaneous dissociation of the cytosolic RII beta(2)C(2) holoenzyme, aberrant RII beta translocation to the nucleus from the cytosol, and retention of RII beta in the nucleus. In conclusion, distinct mechanisms account for deficient PKA-I and PKA-II isozyme activities in SLE T cells.
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Affiliation(s)
- Gary M Kammer
- Section on Rheumatology and Clinical Immunology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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17
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Cui J, Kagan A, Qin D, Mathew J, Melman YF, McDonald TV. Analysis of the cyclic nucleotide binding domain of the HERG potassium channel and interactions with KCNE2. J Biol Chem 2001; 276:17244-51. [PMID: 11278781 DOI: 10.1074/jbc.m010904200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the cyclic nucleotide binding domain (CNBD) of the human ether-a-go-go-related gene (HERG) K+ channel are associated with LQT2, a form of hereditary Long QT syndrome (LQTS). Elevation of cAMP can modulate HERG K+ channels both by direct binding and indirect regulation through protein kinase A. To assess the physiological significance of cAMP binding to HERG, we introduced mutations to disrupt the cyclic nucleotide binding domain. Eight mutants including two naturally occurring LQT2 mutants V822M and R823W were constructed. Relative cAMP binding capacity was reduced or absent in CNBD mutants. Mutant homotetramers carry little or no K+ current despite normal protein abundance and surface expression. Co-expression of mutant and wild-type HERG resulted in currents with altered voltage dependence but without dominant current suppression. The data from co-expression of V822M and wild-type HERG best fit a model where one normal subunit within a tetramer allows nearly normal current expression. The presence of KCNE2, an accessory protein that associates with HERG, however, conferred a partially dominant current suppression by CNBD mutants. Thus KCNE2 plays a pivotal role in determining the phenotypic severity of some forms of LQT2, which suggests that the CNBD of HERG may be involved in its interaction with KCNE2.
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Affiliation(s)
- J Cui
- Section of Molecular Cardiology, Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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18
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Imaizumi-Scherrer T, Faust DM, Barradeau S, Hellio R, Weiss MC. Type I protein kinase a is localized to interphase microtubules and strongly associated with the mitotic spindle. Exp Cell Res 2001; 264:250-65. [PMID: 11262182 DOI: 10.1006/excr.2001.5164] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We show here that type I protein kinase A is localized to microtubules during the entire cell cycle in epithelial (hepatoma, cervical carcinoma) and nonepithelial (myoblast) cell lines. The association of the type Ialpha regulatory subunit is very strong in all phases of mitosis, from prophase to cytokinesis. In interphase, the association appears weaker, reflecting perhaps a more dynamic molecular interaction. This regulatory subunit appears to recruit catalytic subunits as the latter are also associated with microtubules. BW1J hepatoma cells, stably transfected with either wild-type or mutant Ialpha regulatory subunit, are enriched in aberrant mitoses with multipolar spindles and in mono- or multinucleated giant cells. This suggests that type I protein kinase A could have a role in centrosome duplication and/or segregation, sister chromatid separation, or cytokinesis.
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19
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Ochoa de Alda JAG, Houmard J. Genomic survey of cAMP and cGMP signalling components in the cyanobacterium Synechocystis PCC 6803. MICROBIOLOGY (READING, ENGLAND) 2000; 146 Pt 12:3183-3194. [PMID: 11101676 DOI: 10.1099/00221287-146-12-3183] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cyanobacteria modulate intracellular levels of cAMP and cGMP in response to environmental conditions (light, nutrients and pH). In an attempt to identify components of the cAMP and cGMP signalling pathways in Synechocystis PCC 6803, the authors screened its complete genome sequence by using bioinformatic tools and data from sequence-function studies performed on both eukaryotic and prokaryotic cAMP/cGMP-dependent proteins. Sll1624 and Slr2100 were tentatively assigned as being two putative cyclic nucleotide phosphodiesterases. Five proteins were identified as having all the determinants required to be cyclic nucleotide receptors, two of them being probably more specific for cGMP (an element of two-component regulatory systems - Slr2104 - and a putative cyclic-nucleotide-gated cation channel - Slr1575), the three others being probably more specific for cAMP: (i) a protein of unidentified function (Slr0842); (ii) a putative cyclic-nucleotide-modulated permease (Slr0593), previously annotated as a kinase A regulatory subunit; and (iii) a putative transcription factor (CRP-SYN: =Sll1371), which possesses cAMP- and DNA-binding determinants homologous to those of the cAMP receptor protein of Escherichia coli (CRP-EC:). This homology, together with the presence in Synechocystis of CRP-EC:-like binding sites upstream of crp, cya1, slr1575, and several genes encoding enzymes involved in transport and metabolism, strongly suggests that CRP-SYN: is a global regulator.
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Affiliation(s)
- Jesús A G Ochoa de Alda
- Dynamique des Membranes Végétales, Complexes Protéines-Pigments, CNRS UMR 8543, Ecole Normale Supérieure, 46 rue d'Ulm 75230 Paris Cedex 05, France1
| | - Jean Houmard
- Dynamique des Membranes Végétales, Complexes Protéines-Pigments, CNRS UMR 8543, Ecole Normale Supérieure, 46 rue d'Ulm 75230 Paris Cedex 05, France1
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20
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Woo NH, Duffy SN, Abel T, Nguyen PV. Genetic and pharmacological demonstration of differential recruitment of cAMP-dependent protein kinases by synaptic activity. J Neurophysiol 2000; 84:2739-45. [PMID: 11110804 DOI: 10.1152/jn.2000.84.6.2739] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
cAMP-dependent protein kinase (PKA) is believed to play a critical role in the expression of long-lasting forms of hippocampal long-term potentiation (LTP). Can distinct patterns of synaptic activity induce forms of LTP that require different isoforms of PKA? To address this question, we used transgenic mice that have genetically reduced hippocampal PKA activity, and a specific pharmacological inhibitor of PKA, Rp-cAMPS. Transgenic mice [R(AB) mice] that express an inhibitory form of a particular type of regulatory subunit of PKA (type-Ialpha) showed significantly reduced LTP in area CA1 of hippocampal slices as compared with slices from wild-type mice. This impairment of LTP expression was evident when LTP was induced by applying repeated, temporally spaced stimulation (4 1-s bursts of 100-Hz applied once every 5 min). In contrast, LTP induced by applying just 60 pulses in a theta-burst pattern was normal in slices from R(AB) mice as compared with slices from wild-type mice. We found that Rp-cAMPS blocked the expression of LTP induced by both spaced tetra-burst and compressed theta-burst stimulation in hippocampal slices of wild-type and R(AB) mice, respectively. Since Rp-cAMPS is a PKA inhibitor that is not selective for any particular isoform of PKA and these R(AB) mice show reduced hippocampal PKA activity resulting from genetic manipulation of a single isoform of PKA regulatory subunit, our data support the idea that distinct patterns of synaptic activity can produce different forms of LTP that significantly engage different isoforms of PKA. In particular, theta-burst LTP significantly recruits isoforms of PKA containing regulatory subunits other than the mutant RIalpha subunit, whereas tetra-burst LTP requires PKA isoforms containing the mutant RIalpha subunit. Thus, altering both the total amount of imposed synaptic activity and the temporal spacing between bursts of imposed activity may subtly modulate the PKA dependence of hippocampal LTP by engaging distinct isoforms of PKA. In a broader context, our findings suggest that synaptic plasticity in the mammalian brain might be importantly regulated by activity-dependent recruitment of different isoforms of key signal transduction molecules.
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Affiliation(s)
- N H Woo
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
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21
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Laxminarayana D, Kammer GM. mRNA mutations of type I protein kinase A regulatory subunit alpha in T lymphocytes of a subject with systemic lupus erythematosus. Int Immunol 2000; 12:1521-9. [PMID: 11058571 DOI: 10.1093/intimm/12.11.1521] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disorder of indeterminate etiology characterized by multiple T lymphocyte immune effector dysfunctions. Protein kinase A (PKA) isozymes contribute to the regulation of T cell immune effector functions. In SLE T cells, there is a profound deficiency of PKA-I isozyme activity characterized by both reduced RI alpha transcript and RI alpha protein levels. To identify a molecular mechanism(s) for this isozyme deficiency, we utilized single-strand conformation polymorphism (SSCP) analysis to detect structural changes in the cDNA. Of 10 SLE subjects, cDNAs from a single subject revealed a shifted band. Sequence analyses demonstrated that a shifted SSCP band from SLE T cells carried heterogeneous transcript mutations, including deletions, transitions and transversions. Most of these transcript mutations are clustered adjacent to GAGAG motifs and CT repeats-regions that are susceptible to transcript editing and/or molecular misreading. By contrast, no genomic mutations were identified. These results suggest the occurrence of mRNA editing and/or defective function of RNA polymerase in a subject with SLE. Mutant RI alpha transcripts are pathophysiolgically significant, for they can encode diverse, aberrant RI alpha isoforms, including truncated, dominant-negative subunits, resulting in deficient PKA-I activity. We propose that deficient PKA-I isozyme activity contributes to the pathogenesis of SLE by hindering effective signal transduction and impairing T cell effector functions.
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Affiliation(s)
- D Laxminarayana
- Section on Rheumatology and Clinical Immunology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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22
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Sorol MR, Pastori RL, Muro A, Moreno S, Rossi S. Structural and functional analysis of the cAMP binding domain from the regulatory subunit of Mucor rouxii protein kinase A. Arch Biochem Biophys 2000; 382:173-81. [PMID: 11068866 DOI: 10.1006/abbi.2000.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cAMP binding domain of the regulatory subunit (R) of Mucor rouxii protein kinase A was cloned. The deduced amino acid sequence was highly homologous in sequence and in size to the corresponding region in fungal and higher eukaryotic regulatory subunits (47-54%), but particularly homologous (62%) to Blastocladiella emersonii, a fungus classified in a different phylum. Amino acids reported to be important for interaction with cAMP, for cooperativity between the two cAMP binding domains, in the general folding of the domain, and for interaction with the catalytic subunit were conserved in all the fungal sequences. Based on either sequence or functional behavior, the M. rouxii R subunit cannot be classified as being more similar to RI or RII of mammalian systems. The M. rouxii protein sequence was modeled using as template the coordinates of the crystallized bovine regulatory subunit type Ialpha. The quality of the model is good. The two backbones could be perfectly overlapped, except for two loop regions of high divergence. The alpha helix C of domain A, proposed to have a strong interaction with the catalytic subunit, contains a leucine replacing a basic residue (arginine or lysine) commonly found in RI or RII. The domains A and B of the M. rouxii regulatory subunit were overexpressed as fusion proteins with GST. GST domain B protein was inactive. GST domain A was active; the kinetic parameters of affinity toward cAMP analogs, site selectivity, and dissociation kinetics of bound cAMP were analogous to the properties of the domain in the whole regulatory subunit.
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Affiliation(s)
- M R Sorol
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Buenos Aires, Argentina
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23
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Taylor MK, Uhler MD. The amino-terminal cyclic nucleotide binding site of the type II cGMP-dependent protein kinase is essential for full cyclic nucleotide-dependent activation. J Biol Chem 2000; 275:28053-62. [PMID: 10864932 DOI: 10.1074/jbc.m004184200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For the type I cGMP-dependent protein kinases (cGKIalpha and cGKIbeta), a high affinity interaction exists between the C2 amino group of cGMP and the hydroxyl side chain of a threonine conserved in most cGMP binding sites. To examine the effect of this interaction on ligand binding and kinase activation in the type II isozyme of cGMP-dependent protein kinase (cGKII), alanine was substituted for the conserved threonine or serine. cGKII was found to require the C2 amino group of cGMP and its cognate serine or threonine hydroxyl for efficient cGMP activation. Of the two binding sites, disruption of cGMP-specific binding in the NH(2)-terminal binding site had the greatest effect on cGMP-dependent kinase activation, like cGKI. However, ligand dissociation studies showed that the location of the rapid and slow dissociation sites of cGKII was reversed relative to cGKI. Another set of mutations that prevented cyclic nucleotide binding demonstrated the necessity of the NH(2)-terminal, rapid dissociation binding site for cyclic nucleotide-dependent activation of cGKII. These findings suggest distinct mechanisms of activation for cGKII and cGKI isoforms. Because cGKII mediates the effects of heat-stable enterotoxins via the cystic fibrosis transmembrane regulator Cl(-) channel, these findings define a structural target for drug design.
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Affiliation(s)
- M K Taylor
- Department of Biological Chemistry, the Neuroscience Graduate Program, and the Mental Health Research Institute, University of Michigan, Ann Arbor, Michigan 48104, USA
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24
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Francis SH, Corbin JD. Cyclic nucleotide-dependent protein kinases: intracellular receptors for cAMP and cGMP action. Crit Rev Clin Lab Sci 1999; 36:275-328. [PMID: 10486703 DOI: 10.1080/10408369991239213] [Citation(s) in RCA: 219] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Intracellular cAMP and cGMP levels are increased in response to a variety of hormonal and chemical stimuli; these nucleotides play key roles as second messenger signals in modulating myriad physiological processes. The cAMP-dependent protein kinase and cGMP-dependent protein kinase are major intracellular receptors for these nucleotides, and the actions of these enzymes account for much of the cellular responses to increased levels of cAMP or cGMP. This review summarizes many studies that have contributed significantly to an improved understanding of the catalytic, regulatory, and structural properties of these protein kinases. These accumulated findings provide insights into the mechanisms by which these enzymes produce their specific physiological effects and are helpful in considering the actions of other protein kinases as well.
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Affiliation(s)
- S H Francis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA
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25
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Laxminarayana D, Khan IU, Mishra N, Olorenshaw I, Taskén K, Kammer GM. Diminished Levels of Protein Kinase A RIα and RIβ Transcripts and Proteins in Systemic Lupus Erythematosus T Lymphocytes. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.9.5639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Deficient type I protein kinase A phosphotransferase activity occurs in the T cells of 80% of subjects with systemic lupus erythematosus (SLE). To investigate the mechanism of this deficient isozyme activity, we hypothesized that reduced amounts of type I regulatory (RI) isoform transcripts, RIα and RIβ, may be associated with a diminution of RIα and/or RIβ protein. Sixteen SLE subjects with a mean (±1 SD) SLE disease activity index of 12.4 ± 7.2 were studied. Controls included 16 normal subjects, six subjects with primary Sjögren’s syndrome (SS), and three subjects with SS/SLE overlap. RT-PCR revealed that normal, SS, SS/SLE, and SLE T cells expressed mRNAs for all seven R and catalytic (C) subunit isoforms. Quantification of mRNAs by competitive PCR revealed that the ratio of RIα mRNA to RIβ mRNA in normal T cells was 3.4:1. In SLE T cells there were 20 and 49% decreases in RIα and RIβ mRNAs (RIβ; p = 0.008), respectively, resulting in an RIα:RIβ mRNA of 5.3:1. SS/SLE T cells showed a 72.5% decrease in RIβ mRNA compared with normal controls (p = 0.01). Immunoblotting of normal T cell RIα and RIβ proteins revealed a ratio of RIα:RIβ of 3.2:1. In SLE T cells, there was a 30% decrease in RIα protein (p = 0.002) and a 65% decrease in RIβ protein (p < 0.001), shifting the ratio of RIα:RIβ protein to 6.5:1. T cells from 25% of SLE subjects lacked any detectable RIβ protein. Analysis of several lupus T cell lines demonstrated a persistent deficiency of both proteins, excluding a potential effect of disease activity. In conclusion, reduced expression of RIα and RIβ transcripts is associated with a decrement in RIα and RIβ proteins and may contribute to deficient type I protein kinase A isozyme activity in SLE T cells.
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Affiliation(s)
- Dama Laxminarayana
- *Section on Rheumatology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157; and
| | - Islam U. Khan
- *Section on Rheumatology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157; and
| | - Nilamadhab Mishra
- *Section on Rheumatology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157; and
| | - Irene Olorenshaw
- *Section on Rheumatology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157; and
| | - Kjetil Taskén
- †Institute of Medical Biochemistry, University of Oslo, Oslo, Norway
| | - Gary M. Kammer
- *Section on Rheumatology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157; and
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26
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Houslay MD, Sullivan M, Bolger GB. The multienzyme PDE4 cyclic adenosine monophosphate-specific phosphodiesterase family: intracellular targeting, regulation, and selective inhibition by compounds exerting anti-inflammatory and antidepressant actions. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1998; 44:225-342. [PMID: 9547887 DOI: 10.1016/s1054-3589(08)60128-3] [Citation(s) in RCA: 229] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M D Houslay
- Division of Biochemistry and Molecular Biology, University of Glasgow, Scotland, UK
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27
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Burton KA, Johnson BD, Hausken ZE, Westenbroek RE, Idzerda RL, Scheuer T, Scott JD, Catterall WA, McKnight GS. Type II regulatory subunits are not required for the anchoring-dependent modulation of Ca2+ channel activity by cAMP-dependent protein kinase. Proc Natl Acad Sci U S A 1997; 94:11067-72. [PMID: 9380760 PMCID: PMC23603 DOI: 10.1073/pnas.94.20.11067] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/1997] [Indexed: 02/05/2023] Open
Abstract
Preferential phosphorylation of specific proteins by cAMP-dependent protein kinase (PKA) may be mediated in part by the anchoring of PKA to a family of A-kinase anchor proteins (AKAPs) positioned in close proximity to target proteins. This interaction is thought to depend on binding of the type II regulatory (RII) subunits to AKAPs and is essential for PKA-dependent modulation of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate receptor, the L-type Ca2+ channel, and the KCa channel. We hypothesized that the targeted disruption of the gene for the ubiquitously expressed RIIalpha subunit would reveal those tissues and signaling events that require anchored PKA. RIIalpha knockout mice appear normal and healthy. In adult skeletal muscle, RIalpha protein levels increased to partially compensate for the loss of RIIalpha. Nonetheless, a reduction in both catalytic (C) subunit protein levels and total kinase activity was observed. Surprisingly, the anchored PKA-dependent potentiation of the L-type Ca2+ channel in RIIalpha knockout skeletal muscle was unchanged compared with wild type although it was more sensitive to inhibitors of PKA-AKAP interactions. The C subunit colocalized with the L-type Ca2+ channel in transverse tubules in wild-type skeletal muscle and retained this localization in knockout muscle. The RIalpha subunit was shown to bind AKAPs, although with a 500-fold lower affinity than the RIIalpha subunit. The potentiation of the L-type Ca2+ channel in RIIalpha knockout mouse skeletal muscle suggests that, despite a lower affinity for AKAP binding, RIalpha is capable of physiologically relevant anchoring interactions.
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Affiliation(s)
- K A Burton
- Department of Pharmacology, University of Washington School of Medicine, Box 357750, Seattle, WA 98195-7750, USA
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28
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Reed RB, Sandberg M, Jahnsen T, Lohmann SM, Francis SH, Corbin JD. Fast and slow cyclic nucleotide-dissociation sites in cAMP-dependent protein kinase are transposed in type Ibeta cGMP-dependent protein kinase. J Biol Chem 1996; 271:17570-5. [PMID: 8663415 DOI: 10.1074/jbc.271.29.17570] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Both cyclic GMP-dependent protein kinase (cGK) and cyclic AMP-dependent protein kinase (cAK) contain two distinct cyclic nucleotide-binding sites referred to as fast and slow sites based on cyclic nucleotide dissociation behavior. In cAK, the fast site lies amino-terminal to the slow site, and sequence homologies between cAK and cGK have suggested similar positioning for the sites in cGK. Recombinant human type Ibeta cGK (wild type (WT) cGK) was overexpressed, and the properties of purified WT cGK and native type Ibeta cGK were similar. cGK was mutated singly at Thr-193 (T193A, T193V, and T193S) and Thr-317 (T317A, T317V, and T317S), which have been predicted to provide cGMP specificity in the cGMP-binding sites of cGK; a double mutant (T193A/T317A) was produced also. Compared with WT cGK, half-maximal activation (Ka) of mutant cGKs by cGMP was increased 2- (T317A), 27- (T193A), or 63-fold (T193A/T317A), but the Ka for cAMP of these mutants was essentially unchanged. The T193A and T193V mutants had a large increase in the rate of the slow component of [3H]cGMP dissociation, but in the T317A and T317V mutants, there was no change in the slow component. The T193S and T317S mutants had only minor effects on [3H]cGMP dissociation, thus establishing the importance of the hydroxyl group of Thr-193 and -317 for cGMP binding to cGK. Thus, in type Ibeta cGK, the slow cGMP-binding site is identified as the amino-terminal site in contrast to the order assigned to the fast and slow cAMP-binding sites of cAK.
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Affiliation(s)
- R B Reed
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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29
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Su Y, Dostmann WR, Herberg FW, Durick K, Xuong NH, Ten Eyck L, Taylor SS, Varughese KI. Regulatory subunit of protein kinase A: structure of deletion mutant with cAMP binding domains. Science 1995; 269:807-13. [PMID: 7638597 DOI: 10.1126/science.7638597] [Citation(s) in RCA: 303] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In the molecular scheme of living organisms, adenosine 3',5'-monophosphate (cyclic AMP or cAMP) has been a universal second messenger. In eukaryotic cells, the primary receptors for cAMP are the regulatory subunits of cAMP-dependent protein kinase. The crystal structure of a 1-91 deletion mutant of the type I alpha regulatory subunit was refined to 2.8 A resolution. Each of the two tandem cAMP binding domains provides an extensive network of hydrogen bonds that buries the cyclic phosphate and the ribose between two beta strands that are linked by a short alpha helix. Each adenine base stacks against an aromatic ring that lies outside the beta barrel. This structure provides a molecular basis for understanding how cAMP binds cooperatively to its receptor protein, thus mediating activation of the kinase.
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Affiliation(s)
- Y Su
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla 92093-0654, USA
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30
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Zorn M, Fladmark KE, Ogreid D, Jastorff B, Døskeland SO, Dostmann WR. Ala335 is essential for high-affinity cAMP-binding of both sites A and B of cAMP-dependent protein kinase type I. FEBS Lett 1995; 362:291-4. [PMID: 7729515 DOI: 10.1016/0014-5793(95)00261-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A single amino acid substitution (Ala335Asp) in cAMP binding site B of the regulatory subunit of cAMP-dependent protein kinase type I was sufficient to abolish high affinity cAMP binding for both cAMP binding sites A and B. Furthermore, the Ala335Asp mutation increased the activation constant for cAMP of the mutant holoenzyme 30-fold and also enhanced the rate of holoenzyme formation. Thus, the substitution was responsible for the dominant negative phenotype of the enzyme. Activation of mutant holoenzyme with site-selective cAMP analogs indicated that the enzyme dissociated through binding to site A only. Our results provide evidence that Ala335 is an essential residue for high affinity cAMP binding of both sites as well as for the functional integrity of the enzyme.
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Affiliation(s)
- M Zorn
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
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31
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Ogreid D, Dostmann W, Genieser HG, Niemann P, Døskeland SO, Jastorff B. (Rp)- and (Sp)-8-piperidino-adenosine 3',5'-(cyclic)thiophosphates discriminate completely between site A and B of the regulatory subunits of cAMP-dependent protein kinase type I and II. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 221:1089-94. [PMID: 8181466 DOI: 10.1111/j.1432-1033.1994.tb18828.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
8-Piperidino-cAMP has been shown to bind with high affinity to site A of the regulatory subunit of cAMP-dependent protein kinase type I (AI) whereas it is partially excluded from the homologous site (AII) of isozyme II [Ogreid, D., Ekanger, R., Suva, R. H., Miller, J. P., and Døskeland, S. O. (1989), Eur. J. Biochem. 181, 19-31]. To further increase this selectivity, the (Rp)- and (Sp)-diastereoisomers of 8-piperidino-cAMP[S] were synthesized and analyzed for their potency to inhibit binding of [3H]cAMP to site A and site B from type I (rabbit skeletal muscle) and type II (bovine myocardium) cAMP-dependent protein kinases. (Sp)-8-Piperidino-cAMP[S] showed an enhanced relative affinity for site AI, thus being by far the best A-selective compound (more than 100-fold) tested for this isozyme. In contrast, the (Rp)-isomer was less selective for AI than 8-Piperidino-cAMP itself. The reduction in affinities for BII, compared to 8-piperidino-cAMP, were 10-fold and 50-fold for the (Sp)- and (Rp)-isomer, respectively. Both isomers were almost completely excluded from AII, with affinities about 1000-fold lower than 8-piperidino-cAMP itself. The (Rp)-isomer selected BII with an affinity about 10,000 times higher than for AII, whereas the (Sp)-isomer showed a preference of about 70,000-fold in favour of BII. 8-Piperidino-cAMP as well as its (Sp)-isomer activated both types of holoenzyme protein kinases whereas the (Rp)-isomer acted as an antagonist of cAMP-induced activation. The study concludes that the combination of piperidino- and exocyclic sulfur substitutions generate cAMP analogs that completely discriminate between site A and B of cAMP-dependent protein kinases.
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Affiliation(s)
- D Ogreid
- Center of Molecular Medicine, University of Bergen, Norway
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32
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Migeon J, Nathanson N. Differential regulation of cAMP-mediated gene transcription by m1 and m4 muscarinic acetylcholine receptors. Preferential coupling of m4 receptors to Gi alpha-2. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)36949-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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33
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Nargi JL, Woodford-Thomas TA. Cloning and characterization of a cdc25 phosphatase from mouse lymphocytes. Immunogenetics 1994; 39:99-108. [PMID: 8276463 DOI: 10.1007/bf00188612] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Members of the cdc25 phosphatase family are proposed to function as important regulators of the eukaryotic cell cycle, particularly in the induction of mitotic events. A new cdc25 tyrosine phosphatase, cdc25M1, has been cloned from a mouse pre-B cell cDNA library and characterized. The cdc25M1 protein consists of 465 amino acids with a predicted relative molecular mass (M(r)) of 51,750. Over the highly conserved carboxyl terminal region, the amino acid sequence similarity to the human cdc25 C or Hs1 isoform is 89%, while the overall similarity is 67%. The phosphatase active site is located within residues 367-374. Tissue expression of the cdc25M1 was highest in mouse spleen and thymus by northern blot analysis. The cdc25M1 mRNA was detected in a number of cloned mouse lymphocyte cell lines including both CD8+ and CD4+ cells. cdc25M1 mRNA was shown to be cell cycle-regulated in T cells following interleukin-2 (IL-2)-stimulation. Accumulation of cdc25M1 mRNA occurred at 48 h after IL-2 stimulation, when lymphocytes were progressing from S phase to G2/M phase of the cell cycle. This pattern of expression is in contrast to that observed for other protein tyrosine phosphatases expressed in T lymphocytes including CD45, LRP, SHP, and PEP. The elevation in cdc25M1 mRNA level occurred concomittant to the appearance of the hyperphosphorylated form of p34cdc2 protein kinase. A purified, bacterial-expressed recombinant cdc25M1 phosphatase domain catalyzed the dephosphorylation of p-nitrophenol phosphate, as well as [32P-Tyr] and [32P-Ser/Thr]-containing substrates. Preincubation of p34cdc2 kinase with cdc25M1 activated its histone H1 kinase activity in vitro. These results suggest that cdc25M1 may be involved in regulating the proliferation of mouse T lymphocytes following cytokine stimulation, through its action on p34cdc2 kinase.
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Affiliation(s)
- J L Nargi
- Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110
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34
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Døskeland SO, Maronde E, Gjertsen BT. The genetic subtypes of cAMP-dependent protein kinase--functionally different or redundant? BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1178:249-58. [PMID: 8395890 DOI: 10.1016/0167-4889(93)90201-y] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- S O Døskeland
- Department of Anatomy and Cell Biology, University of Bergen, Norway
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35
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Fukayama S, Tashjian AH, Bringhurst FR. Role of protein kinase A in the regulation of cytosolic free calcium in human osteoblast-like SaOS-2 cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 264:C464-70. [PMID: 8383434 DOI: 10.1152/ajpcell.1993.264.2.c464] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have used wild-type and adenosine 3',5'-cyclic monophosphate (cAMP)-resistant mutant osteoblast-like SaOS-2 cells to investigate the role of protein kinase A (PKA) in the regulation of cytosolic free Ca2+ concentration ([Ca2+]i). Basal levels of [Ca2+]i were the same in wild-type (127 +/- 6.1 nM) and transfected (117 +/- 6.8 nM) SaOS-2 cells, although 45Ca2+ efflux was slower in the transfected cells. In wild-type cells, thapsigargin (TG, > or = 200 nM), an inhibitor of the Ca(2+)-ATPase activity of the endoplasmic reticulum, acutely increased [Ca2+]i (by up to 2-fold), which then returned promptly to basal [Ca2+]i. In cAMP-resistant cells, TG elicited a significantly greater acute rise in [Ca2+]i, which then decayed to an elevated plateau level. In mutant cells, high concentrations of dibutyryladenosine 3',5'-cyclic monophosphate, which overcome the PKA blockade, restored the changes in [Ca2+]i to the wild-type pattern. In cAMP-resistant, TG-blocked cells, ionomycin (or alpha-thrombin) induced a further elevation in [Ca2+]i, which then declined rapidly to the original basal level. We conclude that basal PKA activity is involved actively in regulation of [Ca2+]i in SaOS-2 cells by promoting Ca2+ efflux from the cell and, possibly, by inhibiting Ca2+ release from or stimulating net Ca2+ sequestration into the ER. We have also obtained evidence for an alternate Ca(2+)-triggered Ca2+ reuptake mechanism in SaOS-2 cells that is not dependent on either Ca(2+)-ATPase or PKA.
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Affiliation(s)
- S Fukayama
- Endocrine Unit, Massachusetts General Hospital, Boston
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36
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Zajac JD, Kearns AK, Skurat RM, Kronenberg HM, Bringhurst FR. Regulation of gene transcription and proliferation by parathyroid hormone is blocked in mutant osteoblastic cells resistant to cyclic AMP. Mol Cell Endocrinol 1992; 87:69-77. [PMID: 1359985 DOI: 10.1016/0303-7207(92)90234-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We employed a cyclic AMP-resistant subclone of UMR 106-01 osteoblastic osteosarcoma cells (UMR 4-7) with a regulated, dominant-negative mutation of cyclic AMP-dependent protein kinase (PK-A), to examine the mechanism(s) whereby parathyroid hormone (PTH) regulates growth of these cells. Expression of a transiently transfected CAT reporter gene controlled by the cAMP response element of the rat somatostatin gene ('SST-CAT') was used to monitor PK-A activation in intact cells. Agonist-stimulated SST-CAT expression was specific for agents known to activate adenylate cyclase, required an intact cAMP response element and was specifically blocked following induction of the mutant cAMP-resistant phenotype in UMR 4-7 cells. Inhibition of the proliferation of UMR 106-01 cells by PTH, which is mimicked by forskolin and 8-bromo-cAMP, was blocked completely in mutant cyclic AMP-resistant UMR 4-7 cells. We conclude that control of proliferation in UMR 106-01 cells by PTH involves the cAMP messenger system and requires activation of PK-A.
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Affiliation(s)
- J D Zajac
- Endocrine Unit, Massachusetts General Hospital, Boston 02114
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37
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Jin S, Swinnen J, Conti M. Characterization of the structure of a low Km, rolipram-sensitive cAMP phosphodiesterase. Mapping of the catalytic domain. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)37050-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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38
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Chemically induced murine erythroleukemia cell differentiation is severely impaired when cAMP-dependent protein kinase activity is repressed by transfected genes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41981-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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39
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40
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Systematic mutational analysis of cAMP-dependent protein kinase identifies unregulated catalytic subunits and defines regions important for the recognition of the regulatory subunit. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42904-3] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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41
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Mutating protein kinase cAMP-binding sites into cGMP-binding sites. Mechanism of cGMP selectivity. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54231-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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42
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Boshart M, Weih F, Nichols M, Schütz G. The tissue-specific extinguisher locus TSE1 encodes a regulatory subunit of cAMP-dependent protein kinase. Cell 1991; 66:849-59. [PMID: 1832337 DOI: 10.1016/0092-8674(91)90432-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The tissue-specific extinguisher locus TSE1, a dominant negative regulator of transcription in somatic cell hybrids, acts via a cAMP response element (CRE) to repress activity of a hepatocyte-specific enhancer. Guided by the antagonism between TSE1 and cAMP-mediated signal transduction, we identified the regulatory subunit RI alpha of protein kinase A (PKA) as the product of the TSE1 locus. The evidence derives from concordant expression of RI alpha mRNA and TSE1 genetic activity, high resolution mapping of the RI alpha gene and TSE1 on human chromosome 17, and the ability of a transfected RI alpha cDNA to generate a phenocopy of TSE1-mediated extinction. The mechanism of TSE1/RI alpha-mediated extinction involves repression of basal PKA activity, reduced phosphorylation of CREB at Ser-133, and a corresponding reduction of in vivo protein binding at the target CRE.
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Affiliation(s)
- M Boshart
- Institute of Cell and Tumor Biology, German Cancer Research Center, Heidelberg
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43
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Steinberg RA, Gorman KB, Ogreid D, Døskeland SO, Weber IT. Mutations that alter the charge of type I regulatory subunit and modify activation properties of cyclic AMP-dependent protein kinase from S49 mouse lymphoma cells. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67830-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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44
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Cho-Chung YS, Clair T, Tortora G, Yokozaki H. Role of site-selective cAMP analogs in the control and reversal of malignancy. Pharmacol Ther 1991; 50:1-33. [PMID: 1653961 DOI: 10.1016/0163-7258(91)90071-s] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Two isoforms of cAMP receptor protein, RI and RII, the regulatory subunits of cAMP-dependent protein kinase, transduce opposite signals, the RI being stimulatory and the RII being inhibitory of cell proliferation. In normal cells RI and RII exist at a specific physiological ratio whereas in cancer cells such physiological balance of these receptor proteins is disrupted. Reversal and suppression of malignancy can be achieved when the physiologic ratio of these intracellular signal transducers of cAMP is restored as shown by the use of site-selective cAMP analogs, antisense oligodeoxynucleotides or gene transfer, suggesting new approaches to cancer control.
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Affiliation(s)
- Y S Cho-Chung
- Cellular Biochemistry Section, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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45
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Abstract
The actions of several hormones and neurotransmitters evoke signal transduction pathways which rapidly elevate the cytosolic concentrations of the intracellular messengers, cAMP and cGMP. The cyclic-nucleotide dependent protein kinases, cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG), are the major intracellular receptors of cAMP and cGMP. These enzymes become active upon binding respective cyclic nucleotides and modulate a diverse array of biochemical events through the phosphorylation of specific substrate proteins. The focus of this review is to describe the progress made in understanding the structure and function of both PKA and PKG.
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Affiliation(s)
- J D Scott
- Vollum Institute for Advanced Biomedical Research L-474, Portland, OR 97201-3098
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46
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Identification of the MAP2- and P75-binding domain in the regulatory subunit (RII beta) of type II cAMP-dependent protein kinase. Cloning and expression of the cDNA for bovine brain RII beta. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)45811-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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47
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The rate of recombination of the subunits (RI and C) of cAMP-dependent protein kinase depends on whether one or two cAMP molecules are bound per RI monomer. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45402-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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48
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Cadd GG, Uhler MD, McKnight GS. Holoenzymes of cAMP-dependent protein kinase containing the neural form of type I regulatory subunit have an increased sensitivity to cyclic nucleotides. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45401-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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49
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One amino acid change produces a high affinity cGMP-binding site in cAMP-dependent protein kinase. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)46182-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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50
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Cannon JF, Gitan R, Tatchell K. Yeast cAMP-dependent protein kinase regulatory subunit mutations display a variety of phenotypes. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38484-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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