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Arnold ME, Dostmann WR, Martin J, Previs MJ, Palmer B, LeWinter M, Meyer M. SERCA2a-phospholamban interaction monitored by an interposed circularly permutated green fluorescent protein. Am J Physiol Heart Circ Physiol 2021; 320:H2188-H2200. [PMID: 33861144 DOI: 10.1152/ajpheart.00858.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of phospholamban (PLB) and the sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) is a key regulator of cardiac contractility and a therapeutic target in heart failure (HF). PLB-mediated increases in SERCA2a activity improve cardiac function and HF. Clinically, this mechanism can only be exploited by a general activation of the proteinkinase A (PKA), which is associated with side effects and adverse clinical outcomes. A selective interference of the PLB-SERCA2a interaction is desirable but will require novel tools that allow for an integrated assessment of this interaction under both physiological and pathophysiological conditions. A circularly permutated green fluorescent protein (cpGFP) was interposed between SERCA2a and PLB to result into a single SERCA2a-cpGFP-PLB recombinant protein (SGP). Expression, phosphorylation, fluorescence, and function of SGP were evaluated. Expression of SGP-cDNA results in a functional recombinant protein at the predicted molecular weight. The PLB domain of SGP retains its ability to polymerize and can be phosphorylated by PKA activation. This increases the fluorescent yield of SGP by between 10% and 165% depending on cell line and conditions. In conclusion, a single recombinant fusion protein that combines SERCA2a, a circularly permutated green fluorescent protein, and PLB can be expressed in cells and can be phosphorylated at the PLB domain that markedly increases the fluorescence yield. SGP is a novel cellular SERCA2a-PLB interaction monitor.NEW & NOTEWORTHY This study describes the design and characterization of a novel biosensor that can visualize the interaction of SERCA2a and phospholamban (PLB). The biosensor combines SERCA2a, a circularly permutated green fluorescent protein, and PLB into one recombinant protein (SGP). Proteinkinase A activation results in phosphorylation of the PLB domain and is associated with a marked increase in the fluorescence yield to allow for real-time monitoring of the SERCA2a and PLB interaction in cells.
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Affiliation(s)
- Maren E Arnold
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont.,Institute of Experimental and Clinical Pharmacology und Toxicology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Wolfgang R Dostmann
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Jody Martin
- Department of Pharmacology, School of Medicine, Cardiovascular Research Institute, University of California, Davis, California
| | - Michael J Previs
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Bradley Palmer
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Martin LeWinter
- Department of Medicine and Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Markus Meyer
- Department of Medicine, Lillehei Heart Institute, University of Minnesota College of Medicine, Minneapolis, Minnesota
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2
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Averill AM, Rehman HT, Charles JW, Dinh TA, Danyal K, Verschraegen CF, Stein GS, Dostmann WR, Ramsey JE. Inhibition of the chimeric DnaJ-PKAc enzyme by endogenous inhibitor proteins. J Cell Biochem 2019; 120:13783-13791. [PMID: 30938854 DOI: 10.1002/jcb.28651] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 01/16/2019] [Indexed: 12/22/2022]
Abstract
The chimeric DnaJ-PKAc enzymeresulting from an approximately 400-kb deletion of chromosome 19 is a primary contributor to the oncogenic transformation that occurs in fibrolamellar hepatocellular carcinoma, also called fibrolamellar carcinoma (FLC). This oncogenic deletion juxtaposes exon 1 of the DNAJB1 heat shock protein gene with exon 2 of the PRKACA gene encoding the protein kinase A catalytic subunit, resulting in DnaJ-PKAc fusion under the transcriptional control of the DNAJB1 promoter. The expression of DnaJ-PKAc is approximately 10 times that of wild-type (wt) PKAc catalytic subunits, causing elevated and dysregulated kinase activity that contributes to oncogenic transformation. In normal cells, PKAc activity is regulated by a group of endogenous proteins, termed protein kinase inhibitors (PKI) that competitively inhibit PKAc and assist with the nuclear export of the enzyme. Currently, it is scarcely known whether interactions with PKI are perturbed in DnaJ-PKAc. In this report, we survey existing data sets to assess the expression levels of the various PKI isoforms that exist in humans to identify those that are candidates to encounter DnaJ-PKAc in both normal liver and FLC tumors. We then compare inhibition profiles of wtPKAc and DnaJ-PKAc against PKI and demonstrate that extensive structural homology in the active site clefts of the two enzymes confers similar kinase activities and inhibition by full-length PKI and PKI-derived peptides.
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Affiliation(s)
- April M Averill
- Department of Microbiology and Molecular Genetics, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Hibba Tul Rehman
- Division of Hematology and Oncology, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont.,University of Vermont Cancer Center, Burlington, Vermont
| | - Joseph W Charles
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Timothy A Dinh
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Karamatullah Danyal
- Department of Pathology, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Claire F Verschraegen
- Division of Medical Oncology, The Ohio State Comprehensive Cancer Center, Columbus, Ohio
| | - Gary S Stein
- University of Vermont Cancer Center, Burlington, Vermont.,Department of Biochemistry,, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Wolfgang R Dostmann
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Jon E Ramsey
- University of Vermont Cancer Center, Burlington, Vermont.,Department of Biochemistry,, Larner College of Medicine, University of Vermont, Burlington, Vermont
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3
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Sheehe JL, Bonev AD, Schmoker AM, Ballif BA, Nelson MT, Moon TM, Dostmann WR. Oxidation of cysteine 117 stimulates constitutive activation of the type Iα cGMP-dependent protein kinase. J Biol Chem 2018; 293:16791-16802. [PMID: 30206122 DOI: 10.1074/jbc.ra118.004363] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 09/04/2018] [Indexed: 12/22/2022] Open
Abstract
The type I cGMP-dependent protein kinase (PKG I) is an essential regulator of vascular tone. It has been demonstrated that the type Iα isoform can be constitutively activated by oxidizing conditions. However, the amino acid residues implicated in this phenomenon are not fully elucidated. To investigate the molecular basis for this mechanism, we studied the effects of oxidation using recombinant WT, truncated, and mutant constructs of PKG I. Using an in vitro assay, we observed that oxidation with hydrogen peroxide (H2O2) resulted in constitutive, cGMP-independent activation of PKG Iα. PKG Iα C42S and a truncation construct that does not contain Cys-42 (Δ53) were both constitutively activated by H2O2 In contrast, oxidation of PKG Iα C117S maintained its cGMP-dependent activation characteristics, although oxidized PKG Iα C195S did not. To corroborate these results, we also tested the effects of our constructs on the PKG Iα-specific substrate, the large conductance potassium channel (KCa 1.1). Application of WT PKG Iα activated by either cGMP or H2O2 increased the open probabilities of the channel. Neither cGMP nor H2O2 activation of PKG Iα C42S significantly increased channel open probabilities. Moreover, cGMP-stimulated PKG Iα C117S increased KCa 1.1 activity, but this effect was not observed under oxidizing conditions. Finally, we observed that PKG Iα C42S caused channel flickers, indicating dramatically altered KCa 1.1 channel characteristics compared with channels exposed to WT PKG Iα. Cumulatively, these results indicate that constitutive activation of PKG Iα proceeds through oxidation of Cys-117 and further suggest that the formation of a sulfur acid is necessary for this phenotype.
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Affiliation(s)
- Jessica L Sheehe
- From the Department of Pharmacology, Larner College of Medicine, and
| | - Adrian D Bonev
- From the Department of Pharmacology, Larner College of Medicine, and
| | - Anna M Schmoker
- the Department of Biology, University of Vermont, Burlington, Vermont 05405 and
| | - Bryan A Ballif
- the Department of Biology, University of Vermont, Burlington, Vermont 05405 and
| | - Mark T Nelson
- From the Department of Pharmacology, Larner College of Medicine, and
| | - Thomas M Moon
- the Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
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4
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Moon TM, Sheehe JL, Nukareddy P, Nausch LW, Wohlfahrt J, Matthews DE, Blumenthal DK, Dostmann WR. An N-terminally truncated form of cyclic GMP-dependent protein kinase Iα (PKG Iα) is monomeric and autoinhibited and provides a model for activation. J Biol Chem 2018; 293:7916-7929. [PMID: 29602907 DOI: 10.1074/jbc.ra117.000647] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/26/2018] [Indexed: 01/08/2023] Open
Abstract
The type I cGMP-dependent protein kinases (PKG I) serve essential physiological functions, including smooth muscle relaxation, cardiac remodeling, and platelet aggregation. These enzymes form homodimers through their N-terminal dimerization domains, a feature implicated in regulating their cooperative activation. Previous investigations into the activation mechanisms of PKG I isoforms have been largely influenced by structures of the cAMP-dependent protein kinase (PKA). Here, we examined PKG Iα activation by cGMP and cAMP by engineering a monomeric form that lacks N-terminal residues 1-53 (Δ53). We found that the construct exists as a monomer as assessed by whole-protein MS, size-exclusion chromatography, and small-angle X-ray scattering (SAXS). Reconstruction of the SAXS 3D envelope indicates that Δ53 has a similar shape to the heterodimeric RIα-C complex of PKA. Moreover, we found that the Δ53 construct is autoinhibited in its cGMP-free state and can bind to and be activated by cGMP in a manner similar to full-length PKG Iα as assessed by surface plasmon resonance (SPR) spectroscopy. However, we found that the Δ53 variant does not exhibit cooperative activation, and its cyclic nucleotide selectivity is diminished. These findings support a model in which, despite structural similarities, PKG Iα activation is distinct from that of PKA, and its cooperativity is driven by in trans interactions between protomers.
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Affiliation(s)
- Thomas M Moon
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405.
| | - Jessica L Sheehe
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Praveena Nukareddy
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405
| | - Lydia W Nausch
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Jessica Wohlfahrt
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Dwight E Matthews
- Department of Chemistry, University of Vermont, Burlington, Vermont 05405
| | - Donald K Blumenthal
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112
| | - Wolfgang R Dostmann
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405.
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5
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Arora K, Sinha C, Zhang W, Moon CS, Ren A, Yarlagadda S, Dostmann WR, Adebiyi A, Haberman Y, Denson LA, Wang X, Naren AP. Altered cGMP dynamics at the plasma membrane contribute to diarrhea in ulcerative colitis. Am J Pathol 2015; 185:2790-804. [PMID: 26261085 DOI: 10.1016/j.ajpath.2015.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 05/31/2015] [Accepted: 06/29/2015] [Indexed: 12/19/2022]
Abstract
Ulcerative colitis (UC) belongs to inflammatory bowel disorders, a group of gastrointestinal disorders that can produce serious recurring diarrhea in affected patients. The mechanism for UC- and inflammatory bowel disorder-associated diarrhea is not well understood. The cystic fibrosis transmembrane-conductance regulator (CFTR) chloride channel plays an important role in fluid and water transport across the intestinal mucosa. CFTR channel function is regulated in a compartmentalized manner through the formation of CFTR-containing macromolecular complexes at the plasma membrane. In this study, we demonstrate the involvement of a novel macromolecular signaling pathway that causes diarrhea in UC. We found that a nitric oxide-producing enzyme, inducible nitric oxide synthase (iNOS), is overexpressed under the plasma membrane and generates compartmentalized cGMP in gut epithelia in UC. The scaffolding protein Na(+)/H(+) exchanger regulatory factor 2 (NHERF2) bridges iNOS with CFTR, forming CFTR-NHERF2-iNOS macromolecular complexes that potentiate CFTR channel function via the nitric oxide-cGMP pathway under inflammatory conditions both in vitro and in vivo. Potential disruption of these complexes in Nherf2(-/-) mice may render them more resistant to CFTR-mediated secretory diarrhea than Nherf2(+/+) mice in murine colitis models. Our study provides insight into the mechanism of pathophysiologic occurrence of diarrhea in UC and suggests that targeting CFTR and CFTR-containing macromolecular complexes will ameliorate diarrheal symptoms and improve conditions associated with inflammatory bowel disorders.
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Affiliation(s)
- Kavisha Arora
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Chandrima Sinha
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Weiqiang Zhang
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Chang Suk Moon
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Aixia Ren
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Sunitha Yarlagadda
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | | | - Adebowale Adebiyi
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Yael Haberman
- Division of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Lee A Denson
- Division of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Xusheng Wang
- Department of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Anjaparavanda P Naren
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee.
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6
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Lee DI, Zhu G, Sasaki T, Cho GS, Hamdani N, Holewinski R, Jo SH, Danner T, Zhang M, Rainer PP, Bedja D, Kirk JA, Ranek MJ, Dostmann WR, Kwon C, Margulies KB, Van Eyk JE, Paulus WJ, Takimoto E, Kass DA. Phosphodiesterase 9A controls nitric-oxide-independent cGMP and hypertrophic heart disease. Nature 2015; 519:472-6. [PMID: 25799991 PMCID: PMC4376609 DOI: 10.1038/nature14332] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 02/16/2015] [Indexed: 12/11/2022]
Abstract
Cyclic guanosine monophosphate (cGMP) is a second messenger molecule that transduces nitric oxide (NO) and natriuretic peptide (NP) coupled signaling, stimulating phosphorylation changes by protein kinase G (PKG). Enhancing cGMP synthesis or blocking its degradation by phosphodiesterase type 5A (PDE5A) protects against cardiovascular disease1,2. However, cGMP stimulation alone is limited by counter-adaptions including PDE upregulation3. Furthermore, though PDE5A regulates NO-generated cGMP4,5, NO-signaling is often depressed by heart disease6. PDEs controlling NP-coupled cGMP remain uncertain. Here we show that cGMP-selective PDE9A7,8 is expressed in mammalian heart including humans, and is upregulated by hypertrophy and cardiac failure. PDE9A regulates NP rather than NO-stimulated cGMP in heart myocytes and muscle, and its genetic or selective pharmacological inhibition protects against pathological responses to neuro-hormones, and sustained pressure-overload stress. PDE9A inhibition reverses pre-established heart disease independent of NO-synthase (NOS) activity, whereas PDE5A inhibition requires active NOS. Transcription factor activation and phospho-proteome analyses of myocytes with each PDE selectively inhibited reveals substantial differential targeting, with phosphorylation changes from PDE5A inhibition being more sensitive to NOS activation. Thus, unlike PDE5A, PDE9A can regulate cGMP signaling independent of the NO-pathway, and its role in stress-induced heart disease suggests potential as a therapeutic target.
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Affiliation(s)
- Dong I Lee
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Guangshuo Zhu
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Takashi Sasaki
- Advanced Medical Research Laboratories, Research Division, Mitsubishi Tanabe Pharma Corporation, Yokohama, Kanagawa 227-0033, Japan
| | - Gun-Sik Cho
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Nazha Hamdani
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Ronald Holewinski
- 1] Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA [2] Heart Institute and Advanced Clinical Biosystems Research Institute, Cedar Sinai Medical Center, 8700 Beverly Blvd, AHSP A9229 Los Angeles, California 90048, USA
| | - Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University College of Medicine, Chuncheon 200-701, Korea
| | - Thomas Danner
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Manling Zhang
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Peter P Rainer
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Djahida Bedja
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Jonathan A Kirk
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Mark J Ranek
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Wolfgang R Dostmann
- Department of Pharmacology, University of Vermont, Burlington, Vermont 05405, USA
| | - Chulan Kwon
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - Kenneth B Margulies
- Department of Medicine, Division of Cardiovascular Medicine, Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jennifer E Van Eyk
- 1] Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA [2] Heart Institute and Advanced Clinical Biosystems Research Institute, Cedar Sinai Medical Center, 8700 Beverly Blvd, AHSP A9229 Los Angeles, California 90048, USA
| | - Walter J Paulus
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Eiki Takimoto
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
| | - David A Kass
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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7
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Moon TM, Osborne BW, Dostmann WR. The switch helix: a putative combinatorial relay for interprotomer communication in cGMP-dependent protein kinase. Biochim Biophys Acta 2013; 1834:1346-51. [PMID: 23416533 DOI: 10.1016/j.bbapap.2013.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/04/2013] [Indexed: 11/26/2022]
Abstract
For over three decades the isozymes of cGMP-dependent protein kinase (PKG) have been studied using an array of biochemical and biophysical techniques. When compared to its closest cousin, cAMP-dependent protein kinase (PKA), these studies revealed a set of identical domain types, yet containing distinct, sequence-specific features. The recently solved structure of the PKG regulatory domain showed the presence of the switch helix (SW), a novel motif that promotes the formation of a domain-swapped dimer in the asymmetric unit. This dimer is mediated by the interaction of a knob motif on the C-terminal locus of the SW, with a hydrophobic nest on the opposing protomer. This nest sits adjacent to the cGMP binding pocket of the B-site. Priming of this site by cGMP may influence the geometry of the hydrophobic nest. Moreover, this unique interaction may have wide implications for the architecture of the inactive and active forms of PKG. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).
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Affiliation(s)
- Thomas M Moon
- Department of Pharmacology, The University of Vermont, Burlington, VT 05405, USA
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8
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Abstract
Real-time and noninvasive imaging of intracellular second messengers in mammalian cells, while -preserving their in vivo phenotype, requires biosensors of exquisite constitution. Here we provide the methodology for utilizing the single wavelength cGMP-biosensor δ-FlincG in aortic vascular smooth muscle cells.
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Affiliation(s)
- Kara F Held
- Department of Pharmacology, Yale University, New Haven, USA
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9
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Held KF, Dostmann WR. Sub-Nanomolar Sensitivity of Nitric Oxide Mediated Regulation of cGMP and Vasomotor Reactivity in Vascular Smooth Muscle. Front Pharmacol 2012; 3:130. [PMID: 22807915 PMCID: PMC3395022 DOI: 10.3389/fphar.2012.00130] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/20/2012] [Indexed: 11/20/2022] Open
Abstract
Nitric oxide (NO) is a potent dilator of vascular smooth muscle (VSM) by modulating intracellular cGMP ([cGMP]i) through the binding and activation of receptor guanylyl cylases (sGC). The kinetic relationship of NO and sGC, as well as the subsequent regulation of [cGMP]i and its effects on blood vessel vasodilation, is largely unknown. In isolated VSM cells exposed to both pulsed and clamped NO we observed transient and sustained increases in [cGMP]i, with sub-nanomolar sensitivity to NO (EC50 = 0.28 nM). Through the use of pharmacological inhibitors of sGC, PDE5, and PKG, a comprehensive VSM-specific modeling algorithm was constructed to elucidate the concerted activity profiles of sGC, PDE5, phosphorylated PDE5, and PDE1 in the maintenance of [cGMP]i. In small pressure-constricted arteries of the resistance vasculature we again observed both transient and sustained relaxations upon delivery of pulsed and clamped NO, while maintaining a similarly high sensitivity to NO (EC50 = 0.42 nM). Our results propose an intricate dependency of the messengers and enzymes involved in cGMP homeostasis, and vasodilation in VSM. Particularly, the high sensitivity of sGC to NO in primary tissue indicates how small changes in the concentrations of NO, irrespective of the form of NO delivery, can have significant effects on the dynamic regulation of vascular tone.
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Affiliation(s)
- Kara F Held
- Department of Pharmacology, College of Medicine, University of Vermont Burlington, VT, USA
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10
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Caldwell GB, Howe AK, Nickl CK, Dostmann WR, Ballif BA, Deming PB. Direct modulation of the protein kinase A catalytic subunit α by growth factor receptor tyrosine kinases. J Cell Biochem 2012; 113:39-48. [PMID: 21866565 DOI: 10.1002/jcb.23325] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The cyclic-AMP-dependent protein kinase A (PKA) regulates processes such as cell proliferation and migration following activation of growth factor receptor tyrosine kinases (RTKs), yet the signaling mechanisms that link PKA with growth factor receptors remain largely undefined. Here we report that RTKs can directly modulate the function of the catalytic subunit of PKA (PKA-C) through post-translational modification. In vitro kinase assays revealed that both the epidermal growth factor and platelet derived growth factor receptors (EGFR and PDGFR, respectively) tyrosine phosphorylate PKA-C. Mass spectrometry identified tyrosine 330 (Y330) as a receptor-mediated phosphorylation site and mutation of Y330 to phenylalanine (Y330F) all but abolished the RTK-mediated phosphorylation of PKA-C in vitro. Y330 resides within a conserved region at the C-terminal tail of PKA-C that allosterically regulates enzymatic activity. Therefore, the effect of phosphorylation at Y330 on the activity of PKA-C was investigated. The K(m) for a peptide substrate was markedly decreased when PKA-C subunits were tyrosine phosphorylated by the receptors as compared to un-phosphorylated controls. Importantly, tyrosine-phosphorylated PKA-C subunits were detected in cells stimulated with EGF, PDGF, and Fibroblast growth factor 2 (FGF2) and in fibroblasts undergoing PDGF-mediated chemotaxis. These results demonstrate a direct, functional interaction between RTKs and PKA-C and identify tyrosine phosphorylation as a novel mechanism for regulating PKA activity.
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Affiliation(s)
- George B Caldwell
- Department of Medical Laboratory and Radiation Sciences, The University of Vermont, Burlington, Vermont 05405, USA
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11
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McFarland CJ, Nickl CK, Osborne BW, Sarkar IN, Dostmann WR. cGMP-dependent protein kinase from Toxoplasma gondii: functional expression in E. coli and molecular characterization. BMC Pharmacol 2011. [PMCID: PMC3363240 DOI: 10.1186/1471-2210-11-s1-p45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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12
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Osborne BW, Menke AT, Blumenthal DK, Dostmann WR. A structural analysis of the regulatory domain from the cGMP-dependent protein kinase Iα. BMC Pharmacol 2011. [PMCID: PMC3363249 DOI: 10.1186/1471-2210-11-s1-p53] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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13
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Miller CL, Cai Y, Oikawa M, Thomas T, Dostmann WR, Zaccolo M, Fujiwara K, Yan C. Cyclic nucleotide phosphodiesterase 1A: a key regulator of cardiac fibroblast activation and extracellular matrix remodeling in the heart. Basic Res Cardiol 2011; 106:1023-39. [PMID: 22012077 DOI: 10.1007/s00395-011-0228-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 10/07/2011] [Accepted: 10/10/2011] [Indexed: 11/26/2022]
Abstract
Cardiac fibroblasts become activated and differentiate to smooth muscle-like myofibroblasts in response to hypertension and myocardial infarction (MI), resulting in extracellular matrix (ECM) remodeling, scar formation and impaired cardiac function. cAMP and cGMP-dependent signaling have been implicated in cardiac fibroblast activation and ECM synthesis. Dysregulation of cyclic nucleotide phosphodiesterase (PDE) activity/expression is also associated with various diseases and several PDE inhibitors are currently available or in development for treating these pathological conditions. The objective of this study is to define and characterize the specific PDE isoform that is altered during cardiac fibroblast activation and functionally important for regulating myofibroblast activation and ECM synthesis. We have found that Ca(2+)/calmodulin-stimulated PDE1A isoform is specifically induced in activated cardiac myofibroblasts stimulated by Ang II and TGF-β in vitro as well as in vivo within fibrotic regions of mouse, rat, and human diseased hearts. Inhibition of PDE1A function via PDE1-selective inhibitor or PDE1A shRNA significantly reduced Ang II or TGF-β-induced myofibroblast activation, ECM synthesis, and pro-fibrotic gene expression in rat cardiac fibroblasts. Moreover, the PDE1 inhibitor attenuated isoproterenol-induced interstitial fibrosis in mice. Mechanistic studies revealed that PDE1A modulates unique pools of cAMP and cGMP, predominantly in perinuclear and nuclear regions of cardiac fibroblasts. Further, both cAMP-Epac-Rap1 and cGMP-PKG signaling was involved in PDE1A-mediated regulation of collagen synthesis. These results suggest that induction of PDE1A plays a critical role in cardiac fibroblast activation and cardiac fibrosis, and targeting PDE1A may lead to regression of the adverse cardiac remodeling associated with various cardiac diseases.
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Affiliation(s)
- Clint L Miller
- Department of Pharmacology and Physiology, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box CVRI, Rochester, NY 14642, USA
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Osborne BW, Wu J, McFarland CJ, Nickl CK, Sankaran B, Casteel DE, Woods VL, Kornev AP, Taylor SS, Dostmann WR. Crystal structure of cGMP-dependent protein kinase reveals novel site of interchain communication. Structure 2011; 19:1317-27. [PMID: 21893290 PMCID: PMC3168983 DOI: 10.1016/j.str.2011.06.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 06/08/2011] [Accepted: 06/13/2011] [Indexed: 11/27/2022]
Abstract
The cGMP-dependent protein kinase (PKG) serves as an integral component of second messenger signaling in a number of biological contexts including cell differentiation, memory, and vasodilation. PKG is homodimeric and large conformational changes accompany cGMP binding. However, the structure of PKG and the molecular mechanisms associated with protomer communication following cGMP-induced activation remain unknown. Here, we report the 2.5 Å crystal structure of a regulatory domain construct (aa 78-355) containing both cGMP binding sites of PKG Iα. A distinct and segregated architecture with an extended central helix separates the two cGMP binding domains. Additionally, a previously uncharacterized helical domain (switch helix) promotes the formation of a hydrophobic interface between protomers. Mutational disruption of this interaction in full-length PKG implicates the switch helix as a critical site of dimer communication in PKG biology. These results offer new structural insight into the mechanism of allosteric PKG activation.
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Affiliation(s)
- Brent W. Osborne
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405
| | - Jian Wu
- Department of Pharmacology, University of California San Diego, La Jolla, California 92093
| | - Caitlin J. McFarland
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405
| | - Christian K. Nickl
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405
| | - Banumathi Sankaran
- The Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Darren E. Casteel
- Department of Medicine and Cancer Center, University of California, San Diego, La Jolla, California 92093
| | - Virgil L. Woods
- Department of Medicine and Cancer Center, University of California, San Diego, La Jolla, California 92093
| | - Alexandr P. Kornev
- Department of Pharmacology, University of California San Diego, La Jolla, California 92093
- Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093
| | - Susan S. Taylor
- Department of Pharmacology, University of California San Diego, La Jolla, California 92093
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093
- Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093
| | - Wolfgang R. Dostmann
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405
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Dostmann WR, Osborne BW. Crystal structure of cGMP-dependent protein kinase reveals novel site of interchain communication. BMC Pharmacol 2011. [PMCID: PMC3363170 DOI: 10.1186/1471-2210-11-s1-o13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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16
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Lavogina D, Nickl CK, Enkvist E, Raidaru G, Lust M, Vaasa A, Uri A, Dostmann WR. Adenosine analogue-oligo-arginine conjugates (ARCs) serve as high-affinity inhibitors and fluorescence probes of type I cGMP-dependent protein kinase (PKGIalpha). Biochim Biophys Acta 2010; 1804:1857-68. [PMID: 20406699 PMCID: PMC3071016 DOI: 10.1016/j.bbapap.2010.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 04/12/2010] [Accepted: 04/13/2010] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Type I cGMP-dependent protein kinase (PKGIalpha) belongs to the family of cyclic nucleotide-dependent protein kinases and is one of the main effectors of cGMP. PKGIalpha is involved in regulation of cardiac contractility, vasorelaxation, and blood pressure; hence, the development of potent modulators of PKGIalpha would lead to advances in the treatment of a variety of cardiovascular diseases. AIM Representatives of ARC-type compounds previously characterized as potent inhibitors and high-affinity fluorescent probes of PKA catalytic subunit (PKAc) were tested towards PKGIalpha to determine that ARCs could serve as activity regulators and sensors for the latter protein kinase both in vitro and in complex biological systems. RESULTS Structure-activity profiling of ARCs with PKGIalpha in vitro demonstrated both similarities as well as differences to corresponding profiling with PKAc, whereas ARC-903 and ARC-668 revealed low nanomolar displacement constants and inhibition IC(50) values with both cyclic nucleotide-dependent kinases. The ability of ARC-based fluorescent probes to penetrate cell plasma membrane was demonstrated in the smooth muscle tissue of rat cerebellum isolated arteries, and the compound with the highest affinity in vitro (ARC-903) showed also potential for in vivo applications, fully abolishing the PKG1alpha-induced vasodilation.
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Affiliation(s)
- Darja Lavogina
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Christian K. Nickl
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Erki Enkvist
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Gerda Raidaru
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Marje Lust
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Angela Vaasa
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Asko Uri
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Wolfgang R. Dostmann
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405, USA
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Nickl CK, Raidas SK, Zhao H, Sausbier M, Ruth P, Tegge W, Brayden JE, Dostmann WR. (D)-Amino acid analogues of DT-2 as highly selective and superior inhibitors of cGMP-dependent protein kinase Ialpha. Biochim Biophys Acta 2009; 1804:524-32. [PMID: 20018259 DOI: 10.1016/j.bbapap.2009.12.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 12/01/2009] [Accepted: 12/04/2009] [Indexed: 11/26/2022]
Abstract
The cGMP-dependent protein kinase type I (PKG I) is an essential regulator of cellular function in blood vessels throughout the body. DT-2, a peptidic inhibitor of PKG, has played a central role in determining the molecular mechanisms of vascular control involving PKG and its signaling partners. Here, we report the development of (d)-amino acid DT-2 derivatives, namely the retro-inverso ri-(d)-DT-2 and the all (d)-amino acid analog, (d)-DT-2. Both peptide analogs were potent PKG Ialpha inhibitors with K(i) values of 5.5 nM (ri-(d)-DT-2) and 0.8 nM ((d)-DT-2) as determined using a hyperbolic mixed-type inhibition model. Also, both analogs were proteolytically stable in vivo, showed elevated selectivity, and displayed enhanced membrane translocation properties. Studies on isolated arteries from the resistance vasculature demonstrated that intraluminally perfused (d)-DT-2 significantly inhibited vasodilation induced by 8-Br-cGMP. Furthermore, in vivo application of (d)-DT-2 established a uniform translocation pattern in the resistance vasculature, with exception of the brain. Thus, (d)-DT-2 caused significant increases in mean arterial blood pressure in unrestrained, awake mice. Further, mesenteric arteries isolated from (d)-DT-2 treated animals showed a markedly reduced dilator response to 8-Br-cGMP in vitro. Our results clearly demonstrate that (d)-DT-2 is a superior inhibitor of PKG Ialpha and its application in vivo leads to sustained inhibition of PKG in vascular smooth muscle cells. The discovery of (d)-DT-2 may help our understanding of how blood vessels constrict and dilate and may also aid the development of new strategies and therapeutic agents targeted to the prevention and treatment of vascular disorders such as hypertension, stroke and coronary artery disease.
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Affiliation(s)
- Christian K Nickl
- Department of Pharmacology, University of Vermont, College of Medicine, HSRF 330, 149 Beaumont Avenue, Burlington, VT 05405, USA
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Steiner JA, Carneiro AMD, Wright J, Matthies HJG, Prasad HC, Nicki CK, Dostmann WR, Buchanan CC, Corbin JD, Francis SH, Blakely RD. cGMP-dependent protein kinase Ialpha associates with the antidepressant-sensitive serotonin transporter and dictates rapid modulation of serotonin uptake. Mol Brain 2009; 2:26. [PMID: 19656393 PMCID: PMC2731736 DOI: 10.1186/1756-6606-2-26] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 08/05/2009] [Indexed: 01/09/2023] Open
Abstract
Background The Na+/Cl--dependent serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) is a critical element in neuronal 5-HT signaling, being responsible for the efficient elimination of 5-HT after release. SERTs are not only targets for exogenous addictive and therapeutic agents but also can be modulated by endogenous, receptor-linked signaling pathways. We have shown that neuronal A3 adenosine receptor activation leads to enhanced presynaptic 5-HT transport in vitro and an increased rate of SERT-mediated 5-HT clearance in vivo. SERT stimulation by A3 adenosine receptors derives from an elevation of cGMP and subsequent activation of both cGMP-dependent protein kinase (PKG) and p38 mitogen-activated protein kinase. PKG activators such as 8-Br-cGMP are known to lead to transporter phosphorylation, though how this modification supports SERT regulation is unclear. Results In this report, we explore the kinase isoform specificity underlying the rapid stimulation of SERT activity by PKG activators. Using immortalized, rat serotonergic raphe neurons (RN46A) previously shown to support 8-Br-cGMP stimulation of SERT surface trafficking, we document expression of PKGI, and to a lower extent, PKGII. Quantitative analysis of staining profiles using permeabilized or nonpermeabilized conditions reveals that SERT colocalizes with PKGI in both intracellular and cell surface domains of RN46A cell bodies, and exhibits a more restricted, intracellular pattern of colocalization in neuritic processes. In the same cells, SERT demonstrates a lack of colocalization with PKGII in either intracellular or surface membranes. In keeping with the ability of the membrane permeant kinase inhibitor DT-2 to block 8-Br-cGMP stimulation of SERT, we found that DT-2 treatment eliminated cGMP-dependent kinase activity in PKGI-immunoreactive extracts resolved by liquid chromatography. Similarly, treatment of SERT-transfected HeLa cells with small interfering RNAs targeting endogenous PKGI eliminated 8-Br-cGMP-induced regulation of SERT activity. Co-immunoprecipitation studies show that, in transporter/kinase co-transfected cells, PKGIα specifically associates with hSERT. Conclusion Our findings provide evidence of a physical and compartmentalized association between SERT and PKGIα that supports rapid, 8-Br-cGMP-induced regulation of SERT. We discuss a model wherein SERT-associated PKGIα supports sequentially the mobilization of intracellular transporter-containing vesicles, leading to enhanced surface expression, and the production of catalytic-modulatory SERT phosphorylation, leading to a maximal enhancement of 5-HT clearance capacity.
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Affiliation(s)
- Jennifer A Steiner
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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Pinkse MWH, Rijkers DTS, Dostmann WR, Heck AJR. Mode of action of cGMP-dependent protein kinase-specific inhibitors probed by photoaffinity cross-linking mass spectrometry. J Biol Chem 2009; 284:16354-16368. [PMID: 19369251 DOI: 10.1074/jbc.m808521200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The inhibitor peptide DT-2 (YGRKKRRQRRRPPLRKKKKKH) is the most potent and selective inhibitor of the cGMP-dependent protein kinase (PKG) known today. DT-2 is a construct of a PKG tight binding sequence (W45, LRKKKKKH, KI=0.8 microM) and a membrane translocating sequence (DT-6, YGRKKRRQRRRPP, KI=1.1 microM), that combined strongly inhibits PKG catalyzed phosphorylation (KI=12.5 nM) with approximately 1000-fold selectivity toward PKG over protein kinase A, the closest relative of PKG. However, the molecular mechanism behind this inhibition is not entirely understood. Using a combination of photoaffinity labeling, stable isotope labeling, and mass spectrometry, we have located the binding sites of PKG-specific substrate and inhibitor peptides. Covalent linkage of a PKG-specific substrate analogue was localized in the catalytic core on residues 356-372, also known as the glycine-rich loop, essential for ATP binding. By analogy, the individual inhibitor peptides W45 and DT-6 were also found to cross-link near the glycine-rich loop, suggesting these are both substrate competitive inhibitors. A bifunctional photoreactive analogue of DT-2 was found to generate dimers of PKG. This cross-linking induced covalent PKG dimerization was not observed for an N-terminal deletion mutant of PKG, which lacks the dimerization domain. In addition, non-covalent mass spectrometry was used to determine binding stoichiometry and binding order of the inhibitor peptides. Dimeric PKG binds two W45 and DT-6 peptides, whereas only one DT-2 molecule was observed to bind to the dimeric PKG. Taken together, these findings imply that (i) the two individual components making up DT-2 are both targeted against the substrate-binding site and (ii) binding of a single DT-2 molecule inactivates both PKG monomers simultaneously, which is an indication that (iii) in cGMP-activated PKG the catalytic centers of both subunits may be in each other's proximity.
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Affiliation(s)
- Martijn W H Pinkse
- From the Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnnelaan 16, Utrecht 3584 CA, The Netherlands; Department of Biotechnology, Delft, University of Technology, Delft 2628 BC, The Netherlands
| | - Dirk T S Rijkers
- Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht 3584 CA, The Netherlands
| | - Wolfgang R Dostmann
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Albert J R Heck
- From the Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnnelaan 16, Utrecht 3584 CA, The Netherlands.
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Zhang R, Nickl CK, Mamai A, Flemer S, Natarajan A, Dostmann WR, Madalengoitia JS. Poly-L-proline type II peptide mimics as probes of the active site occupancy requirements of cGMP-dependent protein kinase. ACTA ACUST UNITED AC 2007; 66:151-9. [PMID: 16138853 DOI: 10.1111/j.1399-3011.2005.00280.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Based on the X-ray crystal structure of cAMP-dependent protein kinase (PKA) with the endogenous inhibitor PKI and the X-ray crystal structure of cyclin-dependent kinase 2 (CDK2) with a substrate peptide, a proposal is put forth that some protein kinases bind peptide substrates in their active sites in the poly-L-proline type II (PPII) conformation. In this work, PPII peptide mimics are evaluated as pseudosubstrate inhibitors of cGMP-dependent protein kinase (PKG) to explore if PKG also binds peptide substrates in the PPII conformation. Inhibition data of our PPII mimetics provide evidence that the P-1, P-2, and P-3 residues of substrate peptides bind in the PPII conformation (phi approximately -75 degrees, psi approximately 145 degrees). In addition, the inhibition data also suggest that the P-1, P-2, and P-3 residues in substrate peptides bind with a gauche(-) chi1 angle.
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Affiliation(s)
- R Zhang
- Department of Chemistry, University of Vermont, Burlington, VT 05405, USA
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21
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Nausch LWM, Dostmann WR. FlincGs: novel, non-FRET cGMP biosensors with nanomolar sensitivity for NO-induced signaling. BMC Pharmacol 2007. [DOI: 10.1186/1471-2210-7-s1-s22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
The molecular mechanism of cGMP-dependent protein kinase activation by its allosteric regulator cyclic-3',5'-guanosine monophosphate (cGMP) has been intensely studied. However, the structural as well as thermodynamic changes upon binding of cGMP to type I cGMP-dependent protein kinase are not fully understood. Here we report a cGMP-induced shift of Gibbs free enthalpy (DeltaDeltaGD) of 2.5 kJ.mol-1 as determined from changes in tryptophan fluorescence using urea-induced unfolding for bovine PKG Ialpha. However, this apparent increase in overall stability specifically excluded the N-terminal region of the kinase. Analyses of tryptic cleavage patterns using liquid chromatography-coupled ESI-TOF mass spectrometry and SDS/PAGE revealed that cGMP binding destabilizes the N-terminus at the hinge region, centered around residue 77, while the C-terminus was protected from degradation. Furthermore, two recombinantly expressed mutants: the deletion fragment Delta1-77 and the trypsin resistant mutant Arg77Leu (R77L) revealed that the labile nature of the N-terminus is primarily associated with the hinge region. The R77L mutation not only stabilized the N-terminus but extended a stabilizing effect on the remaining domains of the enzyme as well. These findings support the concept that the hinge region of PKG acts as a stability switch.
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Affiliation(s)
- Arjen Scholten
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405, USA
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Cawley SM, Sawyer CL, Brunelle KF, van der Vliet A, Dostmann WR. Nitric oxide-evoked transient kinetics of cyclic GMP in vascular smooth muscle cells. Cell Signal 2006; 19:1023-33. [PMID: 17207606 DOI: 10.1016/j.cellsig.2006.11.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 11/17/2006] [Indexed: 11/21/2022]
Abstract
Cyclic-3',5'-guanosine monophosphate (cGMP) mediates the intracellular signaling cascade responsible for the nitric oxide (NO) initiated relaxation of vascular smooth muscle (VSM). However, the temporal dynamics, including the regulation of cGMP turnover, are largely unknown. Here we report new mechanistic insights into the kinetics of cGMP synthesis and hydrolysis in primary VSM cells by utilizing FRET-based cGMP-indicators [A. Honda, S.R. Adams, C.L. Sawyer, V. Lev-Ram, R.Y. Tsien, W.R. Dostmann, Proc. Natl. Acad. Sci. U S A 98 (5) (2001) 2437.]. First, 2-(N,N-Diethylamino)-diazenolate 2-oxide (DEA/NO) and 2,2'-(Hydroxynitrosohydrazono)-bis-ethanimine (DETA/NO) induced NO-concentration dependent, transient cGMP responses ("peaks") irrespective of their rates of NO release. The kinetic characteristics of these cGMP peaks were governed by the concerted action of the NO-sensitive guanylyl cyclase (GC) and phosphodiesterase type V (PDE5) as shown by their respective inhibition using 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and Sildenafil. These responses occurred in the presence of moderately elevated cGMP (5-15% FRET ratio), and thus activated PKG and phosphorylated PDE5, suggesting a prominent role for GC in the maintenance and termination of cGMP peaks. Furthermore, cGMP transients could be elicited repeatedly without apparent desensitization of GC or by suppression of cGMP via long-term PDE5 activity. These results demonstrate a continuous sensitivity of the NO/cGMP signaling system, inherent to the phasic nature of smooth muscle physiology.
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Affiliation(s)
- Sharon M Cawley
- Department of Pharmacology, University of Vermont, College of Medicine, Burlington, VT 05405, USA
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Bove PF, Wesley UV, Greul AK, Hristova M, Dostmann WR, van der Vliet A. Nitric oxide promotes airway epithelial wound repair through enhanced activation of MMP-9. Am J Respir Cell Mol Biol 2006; 36:138-46. [PMID: 16980554 PMCID: PMC1899313 DOI: 10.1165/rcmb.2006-0253sm] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The airway epithelium provides a protective barrier against inhaled environmental toxins and microorganisms, and epithelial injury initiates a number of processes to restore its barrier integrity, including activation of matrix metalloproteinases such as MMP-9 (92-kD gelatinase B). Airway epithelial cells continuously produce nitric oxide (NO), which has been linked to cell migration and MMP-9 regulation in several cell types, but the importance of epithelial NO in mediating airway epithelial repair or MMP-9 activation is unknown. Using primary or immortalized human bronchial epithelial cells, we demonstrate that low concentrations of NO promote epithelial cell migration and wound repair in an in vitro wound assay, which was associated with increased localized expression and activation of MMP-9. In addition, in HBE1 cells that were stably transfected with inducible NOS (NOS2), to mimic constitutive epithelial NOS2 expression in vivo, NOS inhibition decreased epithelial wound repair and MMP-9 expression. The stimulatory effects of NO on epithelial wound repair and MMP-9 expression were dependent on cGMP-mediated pathways and were inhibited by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase. Inhibition of cGMP-dependent protein kinase (PKG) attenuated NO-mediated epithelial wound closure, but did not affect MMP-9 expression. However, pharmacologic MMP inhibition and siRNA knockdown of MMP-9 expression demonstrated the contribution of MMP-9 to NO-mediated wound closure. Overall, our results demonstrate that NOS2-derived NO contributes to airway epithelial repair by both PKG-dependent and -independent mechanisms, and involves NO-dependent expression and activation of MMP-9.
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Affiliation(s)
- Peter F Bove
- Department of Pathology, College of Medicine, University of Vermont, Burlington, VT 05405, USA
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25
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Mongillo M, Tocchetti CG, Terrin A, Lissandron V, Cheung YF, Dostmann WR, Pozzan T, Kass DA, Paolocci N, Houslay MD, Zaccolo M. Compartmentalized phosphodiesterase-2 activity blunts beta-adrenergic cardiac inotropy via an NO/cGMP-dependent pathway. Circ Res 2005; 98:226-34. [PMID: 16357307 DOI: 10.1161/01.res.0000200178.34179.93] [Citation(s) in RCA: 224] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
beta-Adrenergic signaling via cAMP generation and PKA activation mediates the positive inotropic effect of catecholamines on heart cells. Given the large diversity of protein kinase A targets within cardiac cells, a precisely regulated and confined activity of such signaling pathway is essential for specificity of response. Phosphodiesterases (PDEs) are the only route for degrading cAMP and are thus poised to regulate intracellular cAMP gradients. Their spatial confinement to discrete compartments and functional coupling to individual receptors provides an efficient way to control local [cAMP]i in a stimulus-specific manner. By performing real-time imaging of cyclic nucleotides in living ventriculocytes we identify a prominent role of PDE2 in selectively shaping the cAMP response to catecholamines via a pathway involving beta3-adrenergic receptors, NO generation and cGMP production. In cardiac myocytes, PDE2, being tightly coupled to the pool of adenylyl cyclases activated by beta-adrenergic receptor stimulation, coordinates cGMP and cAMP signaling in a novel feedback control loop of the beta-adrenergic pathway. In this, activation of beta3-adrenergic receptors counteracts cAMP generation obtained via stimulation of beta1/beta2-adrenoceptors. Our study illustrates the key role of compartmentalized PDE2 in the control of catecholamine-generated cAMP and furthers our understanding of localized cAMP signaling.
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Affiliation(s)
- Marco Mongillo
- Dulbecco Telethon Institute, Venetian Institute of Molecular Medicine, Padova, Italy
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26
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Hou Y, Wong E, Martin J, Schoenlein PV, Dostmann WR, Browning DD. A role for cyclic-GMP dependent protein kinase in anoikis. Cell Signal 2005; 18:882-8. [PMID: 16139477 DOI: 10.1016/j.cellsig.2005.07.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 07/28/2005] [Accepted: 07/28/2005] [Indexed: 11/16/2022]
Abstract
Anoikis is an essential process in which a loss of adhesion to the substratum alters intracellular signaling pathways that lead to apoptosis. Using phosphorylation of vasodilator stimulated phosphoprotein (VASP) as an indicator of cGMP-dependent protein kinase (PKG) activity in vivo, it was found that suspension of the colon epithelial cell line (CCD841) leads to rapid and transient activation of PKG that lasted several hours. The colon carcinoma lines SW480 and SW620 do not express endogenous PKG, but exogenously expressed PKG was similarly activated upon cell suspension. To determine whether PKG has a role in apoptosis following cell suspension, poly-ADP ribose polymerase (PARP) cleavage and propidium iodide staining were measured. After 24 h in suspension it was found that approximately 50% of CCD841 cells exhibited apoptosis, whereas apoptosis was not detected in either of the colon carcinoma cell lines. Inhibition of type 1 PKG by expression of a dominant negative PKG construct (G1alphaR-GFP), or by incubation with the PKG inhibitor peptide DT-2, blocked apoptosis in suspended CCD841 cells by approximately 50%. Furthermore, expression of exogenous PKG in SW620 and SW480 cells conferred partial sensitivity anoikis. Taken together these findings indicate that PKG has an important role in the induction of apoptosis following suspension of normal colon epithelial cells, and loss of PKG expression in colon tumor cells may contribute to resistance to anoikis.
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Affiliation(s)
- Yali Hou
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30809, USA
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Cawley SM, Dostmann WR. Kinetics of NO-induced cyclic GMP responses in vascular smooth muscle. BMC Pharmacol 2005. [DOI: 10.1186/1471-2210-5-s1-p8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Foley KF, De Frutos S, Laskovski KE, Tegge W, Dostmann WR. Culture conditions influence uptake and intracellular localization of the membrane permeable cGMP-dependent protein kinase inhibitor DT-2. FRONT BIOSCI-LANDMRK 2005; 10:1302-12. [PMID: 15769626 DOI: 10.2741/1620] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The membrane-permeable peptide DT-2 which utilizes the HIV-Tat membrane translocation sequence is known to inhibit cGMP-dependent protein kinase (PKG) effectively in vitro and in various cell lines and tissue preparations. However, the uptake characteristics of DT-2 have not been studied in detail. We investigated the intracellular uptake and localization of fluorescein-labeled DT-2 (fDT-2) in cultured C6-glial cells and vascular smooth muscle cells (VSMCs) as well as VSMCs in intact arteries. To avoid fixation-induced fluorescence, live unfixed cells and arteries were incubated with fDT-2 and examined using conventional and confocal fluorescence microscopy. In non-differentiated cultured VSMCs, uptake appeared vesicular with nuclear exclusion, consistent with an endocytotic internalization mechanism. Inhibition of endocytosis by phenylarsine oxide (PAO), low temperature or disruption of actin polymerization by cytochalasin-D or lantrunculin-A showed a residual non-endocytotic fDT-2 translocation with diffuse cytosolic and nuclear uptake. Similarly, differentiated contractile VSMCs within the medial layer of intact cerebral arteries also showed a distinctively different, more diffuse cytosolic uptake and time dependent nuclear localization. To verify the morphology dependency of fDT-2 uptake, VSMCs were reconstituted in fibrillar collagen matrices. The cells adopted a differentiated morphology and fDT-2 translocation was similar to cells in intact arteries. These results demonstrate that VSMCs cells utilize distinct cellular uptake mechanisms depending on their phenotype.
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Affiliation(s)
- Kevin F Foley
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405-0075, USA
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29
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Abstract
We have previously shown that type I cGMP-dependent protein kinase (PKG) can alter the phenotype of cultured vascular smooth muscle cells (VSMCs). Although the expression of contractile proteins in VSMCs has been shown to be modulated with the induction of PKG, experiments in which PKG inhibition brings about reduced expression of contractile markers have not been performed. To more thoroughly examine the role of PKG in the expression of contractile proteins, recombinant adenovirus containing the PKG coding sequence (AD-PKG) was used to induce gene expression and morphologic changes in adult rat aortic VSMCs. Cells expressing PKG, but not control adenovirus-infected cells, began to express a specific marker protein for the contractile phenotype, smooth muscle myosin heavy chain (SMMHC), within 48 hours of PKG induction. The morphology of the AD-PKG-infected cells began to change from a fibroblastic phenotype to a spindle-shaped phenotype within 72 hours after PKG induction. The specific cell-permeable PKG inhibitory peptide DT-2, but not control peptides, reversed the biochemical and morphologic changes associated with PKG expression. These results suggest that PKG expression and activity in cultured VSMCs is capable of altering the VSMC phenotype. These data also verify the intracellular action of DT-2 and reveal uptake and dynamic properties of this PKG-inhibiting peptide.
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Affiliation(s)
- Nupur B Dey
- Department of Physiology, University of South Alabama, College of Medicine, Mobile, Alabama 36688, USA
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Abstract
We have recently developed genetically encoded cGMP-indicators (cygnets) which have enabled us to study the spatial and temporal dynamics of intracellular cGMP in single cultured cells (1). However, primary mammalian cell types (dissociated cells or acute tissue samples) are often difficult to maintain undifferentiated in culture and the current established methods of introducing molecular reporters in single cells are laborious (micro-injection) and/or require cell culture techniques to accommodate the 1-2 day lag time of genetically mediated reporter expression. Here, we present an alternative, non-genetic method to rapidly introduce cGMP-indicators into cells and intact tissues using membrane permeable peptides (MPP). Five different 125 kDa MPP-cygnets were expressed and purified from insect SF9 cells. Three constructs showed high level cGMP-dependent FRET in vitro. One of the probes, Ant7-Cygnet, demonstrated emission ratio changes identical to the unmodified indicator. Ant7-Cygnet was rapidly (3 hours) and efficiently internalized in cultured smooth muscle cells and intact cerebral arteries. Furthermore, the internalized Ant7-Cygnet detected nitric oxide mediated elevations of intracellular cGMP in cultured smooth muscle cells and sensed increased levels of intracellular cGMP derived from C-type natriuretic peptide (CNP) induced guanylyl cyclase stimulation in intact arteries. These results demonstrate that MPP-cygnets provide a novel and potentially powerful technique to study intracellular cGMP in intact tissue.
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Affiliation(s)
- Akira Honda
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington 05405-0075, USA
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Zhu CB, Carneiro AM, Dostmann WR, Hewlett WA, Blakely RD. p38 MAPK Activation Elevates Serotonin Transport Activity via a Trafficking-independent, Protein Phosphatase 2A-dependent Process. J Biol Chem 2005; 280:15649-58. [PMID: 15728187 DOI: 10.1074/jbc.m410858200] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Presynaptic, plasma membrane serotonin (5-hydroxytryptamine; 5-HT) transporters (SERTs) clear 5-HT following vesicular release and are regulated through trafficking-dependent pathways. Recently, we provided evidence for a trafficking-independent mode of SERT regulation downstream of adenosine receptor (AR) activation that is sensitive to p38 MAPK inhibitors. Here, we probe this pathway in greater detail, demonstrating elevation of 5-HT transport by multiple p38 MAPK activators (anisomycin, H(2)O(2), and UV radiation), in parallel with p38 MAPK phosphorylation, as well as suppression of anisomycin stimulation by p38 MAPK siRNA treatments. Studies with transporter-transfected Chinese hamster ovary cells reveal that SERT stimulation is shared with the human norepinephrine transporter but not the human dopamine transporter. Saturation kinetic analyses of anisomycin-SERT activity reveal a selective reduction in 5-HT K(m) supported by a commensurate increase in 5-HT potency (K(i)) for displacing surface antagonist binding. Anisomycin treatments that stimulate SERT activity do not elevate surface SERT surface density whereas stimulation is lost with preexposure of cells to the surface-SERT inactivating reagent, 2-(trimethylammonium)ethyl methane thiosulfonate. Guanylyl cyclase (1H-(1,2,4)-oxadiazolo[4,3-a]-quinoxalin-1-one) and protein kinase G inhibitors (H8, DT-2) block AR stimulation of SERT yet fail to antagonize SERT stimulation by anisomycin. We thus place p38 MAPK activation downstream of protein kinase G in a SERT-catalytic regulatory pathway, distinct from events controlling SERT surface density. In contrast, the activity of protein phosphatase 2A inhibitors (fostriecin and calyculin A) to attenuate anisomycin stimulation of 5-HT transport suggests that protein phosphatase 2A is a critical component of the pathway responsible for p38 MAPK up-regulation of SERT catalytic activity.
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Affiliation(s)
- Chong-Bin Zhu
- Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8548, USA
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Krieg T, Philipp S, Cui L, Dostmann WR, Downey JM, Cohen MV. Peptide blockers of PKG inhibit ROS generation by acetylcholine and bradykinin in cardiomyocytes but fail to block protection in the whole heart. Am J Physiol Heart Circ Physiol 2004; 288:H1976-81. [PMID: 15591097 DOI: 10.1152/ajpheart.00883.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bradykinin and acetylcholine (ACh) trigger preconditioning by ATP-sensitive K(+) (K(ATP)) channel-dependent production of reactive oxygen species (ROS). Recent evidence suggests that ROS production may in turn be influenced by cGMP-dependent protein kinase (PKG). This study utilized DT-2 and DT-3 peptides, highly specific membrane-permeable blockers of PKG. Rabbit cardiomyocytes were incubated for 15 min in reduced MitoTracker red, which becomes fluorescent only after exposure to ROS. Bradykinin (400 nM) and ACh (250 microM) caused a 49.9 +/- 5.9% and 46.8 +/- 1.7% increase in ROS production, respectively (P < 0.005 vs. untreated cells). Coincubation with DT-3 (250 nM) abolished both the ACh- and bradykinin-induced ROS signal, whereas a nonpermeable form of the peptide (W45) had no effect on ACh-induced ROS production. DT-3 was unable to block ROS production from diazoxide (100 microM), a selective opener of mitochondrial K(ATP) channels, suggesting that these channels are downstream of PKG. DT-2 (125 nM) also prevented ACh from triggering ROS production. 8-(4-Chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (100 microM), a cGMP analog and potent direct activator of PKG, increased ROS production of cardiomyocytes by 44.7 +/- 7.1% (P < 0.001 vs. untreated cells). This increase was blocked by DT-2. Neither DT-2 nor DT-3 could block the anti-infarct effect of bradykinin in isolated rabbit hearts. Studies with fluorescent-tagged DT-3 revealed that it was confined to endothelial cells and never reached the myocytes. We conclude that both bradykinin and ACh trigger ROS generation by a pathway that includes PKG. Although the peptides may be inappropriate for a whole heart model, they are likely to become important tool drugs for elucidation of signal transduction pathways in cell preparations.
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Affiliation(s)
- Thomas Krieg
- Dept. of Physiology, MSB 3050, University of South Alabama College of Medicine, Mobile, AL 36688, USA.
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Takimoto E, Champion HC, Belardi D, Moslehi J, Mongillo M, Mergia E, Montrose DC, Isoda T, Aufiero K, Zaccolo M, Dostmann WR, Smith CJ, Kass DA. cGMP catabolism by phosphodiesterase 5A regulates cardiac adrenergic stimulation by NOS3-dependent mechanism. Circ Res 2004; 96:100-9. [PMID: 15576651 DOI: 10.1161/01.res.0000152262.22968.72] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Beta-adrenergic agonists stimulate cardiac contractility and simultaneously blunt this response by coactivating NO synthase (NOS3) to enhance cGMP synthesis and activate protein kinase G (PKG-1). cGMP is also catabolically regulated by phosphodiesterase 5A (PDE5A). PDE5A inhibition by sildenafil (Viagra) increases cGMP and is used widely to treat erectile dysfunction; however, its role in the heart and its interaction with beta-adrenergic and NOS3/cGMP stimulation is largely unknown. In nontransgenic (control) murine in vivo hearts and isolated myocytes, PDE5A inhibition (sildenafil) minimally altered rest function. However, when the hearts or isolated myocytes were stimulated with isoproterenol, PDE5A inhibition was associated with a suppression of contractility that was coupled to elevated cGMP and increased PKG-1 activity. In contrast, NOS3-null hearts or controls with NOS inhibited by N(G)-nitro-L-arginine methyl ester, or soluble guanylate cyclase (sGC) inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one, showed no effect of PDE5A inhibition on beta-stimulated contractility or PKG-1 activation. This lack of response was not attributable to altered PDE5A gene or protein expression or in vitro PDE5A activity, but rather to an absence of sGC-generated cGMP specifically targeted to PDE5A catabolism and to a loss of PDE5A localization to z-bands. Re-expression of active NOS3 in NOS3-null hearts by adenoviral gene transfer restored PDE5A z-band localization and the antiadrenergic efficacy of PDE5A inhibition. These data support a novel regulatory role of PDE5A in hearts under adrenergic stimulation and highlight specific coupling of PDE5A catabolic regulation with NOS3-derived cGMP attributable to protein subcellular localization and targeted synthetic/catabolic coupling.
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Affiliation(s)
- Eiki Takimoto
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Md, USA
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Sawyer CL, Honda A, Dostmann WR. Cygnets: spatial and temporal analysis of intracellular cGMP. Proc West Pharmacol Soc 2003; 46:28-31. [PMID: 14699878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Carolyn L Sawyer
- Department of Pharmacology, University of Vermont, College of Medicine, Burlington, Vermont 05405, USA
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Honda A, Adams SR, Sawyer CL, Lev-Ram V, Tsien RY, Dostmann WR. Spatiotemporal dynamics of guanosine 3',5'-cyclic monophosphate revealed by a genetically encoded, fluorescent indicator. Proc Natl Acad Sci U S A 2001; 98:2437-42. [PMID: 11226257 PMCID: PMC30156 DOI: 10.1073/pnas.051631298] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To investigate the dynamics of guanosine 3',5'-cyclic monophosphate (cGMP) in single living cells, we constructed genetically encoded, fluorescent cGMP indicators by bracketing cGMP-dependent protein kinase (cGPK), minus residues 1-77, between cyan and yellow mutants of green fluorescent protein. cGMP decreased fluorescence resonance energy transfer (FRET) and increased the ratio of cyan to yellow emissions by up to 1.5-fold with apparent dissociation constants of approximately 2 microM and >100:1 selectivity for cGMP over cAMP. To eliminate constitutive kinase activity, Thr(516) of cGPK was mutated to Ala. Emission ratio imaging of the indicators transfected into rat fetal lung fibroblast (RFL)-6 showed cGMP transients resulting from activation of soluble and particulate guanylyl cyclase, respectively, by nitric oxide (NO) and C-type natriuretic peptide (CNP). Whereas all naive cells tested responded to CNP, only 68% responded to NO. Both sets of signals showed large and variable (0.5-4 min) latencies. The phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX) did not elevate cGMP on its own but consistently amplified responses to NO or CNP, suggesting that basal activity of guanylate cyclase is very low and emphasizing the importance of PDEs in cGMP recycling. A fraction of RFL cells showed slowly propagating tides of cGMP spreading across the cell in response to delocalized application of NO. Biolistically transfected Purkinje neurons showed cGMP responses to parallel fiber activity and NO donors, confirming that single-cell increases in cGMP occur under conditions appropriate to cause synaptic plasticity.
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Affiliation(s)
- A Honda
- Department of Pharmacology and Molecular Physiology, University of Vermont, College of Medicine, Burlington, VT 05405-0068, USA
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36
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Dostmann WR, Taylor MS, Nickl CK, Brayden JE, Frank R, Tegge WJ. Highly specific, membrane-permeant peptide blockers of cGMP-dependent protein kinase Ialpha inhibit NO-induced cerebral dilation. Proc Natl Acad Sci U S A 2000; 97:14772-7. [PMID: 11121077 PMCID: PMC18994 DOI: 10.1073/pnas.97.26.14772] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Arrays of octameric peptide libraries on cellulose paper were screened by using (32)P-autophosphorylated cGMP-dependent protein kinase Ialpha (cGPK) to identify peptide sequences with high binding affinity for cGPK. Iterative deconvolution of every amino acid position in the peptides identified the sequence LRK(5)H (W45) as having the highest binding affinity. Binding of W45 to cGPK resulted in selective inhibition of the kinase with K(i) values of 0.8 microM and 560 microM for cGPK and cAMP-dependent protein kinase (cAPK), respectively. Fusion of W45 to membrane translocation signals from HIV-1 tat protein (YGRKKRRQRRRPP-LRK(5)H, DT-2) or Drosophila Antennapedia homeo-domain (RQIKIWFQNRRMKWKK-LRK(5)H, DT-3) proved to be an efficient method for intracellular delivery of these highly charged peptides. Rapid translocation of the peptides into intact cerebral arteries was demonstrated by using fluorescein-labeled DT-2 and DT-3. The inhibitory potency of the fusion peptides was even greater than that for W45, with K(i) values of 12.5 nM and 25 nM for DT-2 and DT-3, respectively. Both peptides were still poor inhibitors of cAPK. Selective inhibition of cGPK by DT-2 or DT-3 in the presence of cAPK was demonstrated in vitro. In pressurized cerebral arteries, DT-2 and DT-3 substantially decreased NO-induced dilation. This study provides functional characterization of a class of selective cGPK inhibitor peptides in vascular smooth muscle and reveals a central role for cGPK in the modulation of vascular contractility.
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Affiliation(s)
- W R Dostmann
- Department of Pharmacology, Department of Molecular Physiology and Biophysics, University of Vermont, College of Medicine, Burlington, VT 05405-0068, USA.
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Dostmann WR, Nickl C, Thiel S, Tsigelny I, Frank R, Tegge WJ. Delineation of selective cyclic GMP-dependent protein kinase Ialpha substrate and inhibitor peptides based on combinatorial peptide libraries on paper. Pharmacol Ther 1999; 82:373-87. [PMID: 10454213 DOI: 10.1016/s0163-7258(98)00063-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Peptide libraries on cellulose paper have proven to be valuable tools for the a priori determination of substrate specificities of cyclic AMP- and cyclic GMP-dependent protein kinases (cAMP-kinase and cGMP-kinase) on the basis of octa-peptide sequences. Here, we report the extension of our peptide library screens to 12-mer and 14-mer peptide sequences, resulting in highly cGMP-kinase Ialpha selective peptides. The sequences TQAKRKKSLAMA-amide and TQAKRKKSLAMFLR-amide, with Km values for cGMP-kinase Ialpha of 0.7 and 0.26 microM and Vmax values of 11.5 and 10.9 micromol/min/mg, respectively, display a high specificity for this enzyme. Furthermore, replacing the phosphate acceptor residue serine with alanine in TQAKRKKSLAMA-amide resulted in the highly cGMP-kinase Ialpha selective inhibitor peptide TQAKRKKALAMA-amide, with inhibitor constants for cGMP-kinase Ialpha and cAMP-kinase of 7.5 microM and 750 microM, respectively. Selective cGMP-kinase inhibitors have the potential to play an important role in the elucidation of the distinct cellular functions of cGMP-kinase separate from those activated by cAMP-kinases, and, therefore, may play an important role as pharmaceutical targets. Molecular docking experiments of the most cGMP-kinase selective sequences on a molecular model of the catalytic domain of cGMP-kinase Ialpha suggest that they adopt unique conformations, which differ significantly from those observed for the cAMP-kinase-specific inhibitor PKI(5-24). Our results suggest that despite their structural similarities, cAMP-kinase and cGMP-kinase use distinct peptide substrate and inhibitor conformations, which could account for their unique substrate specificities. These findings are further supported by cAMP- and cGMP-kinase-selective inhibitor analogs with (D)-Ala residues at the inhibitory positions.
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Affiliation(s)
- W R Dostmann
- Department of Pharmacology, University of Vermont, College of Medicine, Burlington 05405, USA
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Ruth P, Pfeifer A, Kamm S, Klatt P, Dostmann WR, Hofmann F. Identification of the amino acid sequences responsible for high affinity activation of cGMP kinase Ialpha. J Biol Chem 1997; 272:10522-8. [PMID: 9099696 DOI: 10.1074/jbc.272.16.10522] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The cGMP-dependent protein kinases (cGK) Ialpha and Ibeta have identical cGMP binding sites and catalytic domains. However, differences in their first 100 amino acids result in 15-fold different activation constants for cGMP. We constructed chimeras to identify those amino acid sequences that contribute to the high affinity cGK Ialpha and low affinity cGK Ibeta phenotype. The cGK Ialpha/Ibeta chimeras contained permutations of six amino-terminal regions (S1-S6) including the leucine zipper (S2), the autoinhibitory domain (S4), and the hinge domain (S5, S6). The exchange of S2 along with S4 switched the phenotype from cGK Ialpha to cGK Ibeta and vice versa, suggesting that the domains with the highest homology between the two isozymes determine their affinity for cGMP. The high affinity cGK Ialpha phenotype was also obtained by a specific substitution within the hinge domain. Chimeras with the sequence of cGK Ialpha in S5 and cGK Ibeta in S6 were activated at up to 6-fold lower cGMP concentrations than cGK Ialpha. Based on the activation constants of all chimeras constructed, empirical weighting factors have been calculated that quantitatively describe the contribution of the individual amino-terminal domains S1-S6 to the high affinity cGK Ialpha phenotype.
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Affiliation(s)
- P Ruth
- Institut für Pharmakologie und Toxikologie der Technische Universität München, Biedersteiner Strasse 29, D-80802 München, Germany.
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Dostmann WR, Koep N, Endres R. The catalytic domain of the cGMP-dependent protein kinase Ialpha modulates the cGMP-binding characteristics of its regulatory domain. FEBS Lett 1996; 398:206-10. [PMID: 8977108 DOI: 10.1016/s0014-5793(96)01242-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The cGMP-dependent protein kinase Ialpha (PKG Ialpha) possesses two functional moieties, the regulatory and catalytic domains, which reside on a single polypeptide chain. Here we report on the influence of the catalytic domain on the binding of cGMP to the regulatory domain. A deletion mutant, delta352-670 of PKG Ialpha, lacking the catalytic domain, was constructed and expressed in E. coli. The purified 38 kDa mutant protein showed strong reactivity toward tryptic proteolysis at residue Arg77. Thus, a double deletion fragment delta1-77/352-670 PKG Ialpha, lacking the N-terminus, was also purified. Both proteins had functional cGMP binding, but differed kinetically from the wild-type protein. First the affinity constants for cGMP were modulated, second the constructs showed no signs of cooperative cGMP binding and third dimerization of the delta352-670 mutant was abolished. Our results provide evidence that the catalytic domain forms an intimate interaction with the regulatory domain and modulates the kinetics of cGMP binding.
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Affiliation(s)
- W R Dostmann
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany.
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Huq I, Dostmann WR, Ogreid D. Isoleucine 368 is involved in low-affinity binding of N6-modified cAMP analogues to site B of the regulatory subunit of cAMP-dependent protein kinase I. Biochem J 1996; 316 ( Pt 1):337-43. [PMID: 8645227 PMCID: PMC1217344 DOI: 10.1042/bj3160337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The regulatory (R) subunit of cAMP-dependent protein kinase has a well-defined domain structure including the two in-tandem cAMP-binding sites that constitute the C-terminus of the protein. The N-terminal binding site (A) has a considerably higher affinity for analogues of cAMP that are substituted with bulky and hydrophobic substituents at the 6-amino group of the adenine ring compared to the affinity observed at the second site (B). On the basis of the crystal structure of the catabolite gene activator protein from Escherichia coli, molecular modelling of the binding domains suggested that a tyrosine (Y244) in site A could be involved in a high-affinity hydrophobic interaction, whereas a corresponding isoleucine (I368) in domain B could lead to steric hindrance in the binding of bulky N6-substituted analogues. Site-directed mutagenesis was used to construct mutations in Y244 and I368. Binding displacement experiments showed that replacing the tyrosine in site A with isoleucine (Y244I) did not affect the interaction of either N6-substituted or otherwise modified analogues with this site. However, replacing I368 with tyrosine (I368Y) led to a 3-4-fold increase in affinity for those N6-modified analogues that had a hydrophobic group attached directly or close to the 6-amino molecule. We conclude that I368 is involved in the molecular interaction between binding domain B and the 6-amino group of the adenine moiety of cAMP and that this residue is partly responsible for the reduced affinity of N6-substituted cAMP analogues for this site.
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Affiliation(s)
- I Huq
- University of Bergen, Center of Molecular Medicine, Haukeland Hospital, Norway
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Abstract
cAMP-dependent protein kinase (cAPK) is a heterotetramer containing two regulatory (R) and two catalytic (C) subunits. Each R-subunit contains two tandem cAMP-binding domains, and activation of cAPK is mediated by the cooperative, high affinity binding of cAMP to these two domains. Mutant R-subunits containing one intact high affinity cAMP-binding site and one defective site were used to define the pathway for activation and to delineate the unique roles that each cAMP-binding domain plays. Two mutations were introduced by replacing the essential Arg in each cAMP-binding site with Lys (R209K in Site A and R333K in Site B). Also, the double mutant (R209/333K) was constructed. Analysis of cAMP binding and dissociation and the apparent constants for holoenzyme activation and R- and C-subunit interaction, measured by analytical gel filtration and surface plasmon resonance, established the following: (1) For rR(R209K), occupancy of Site B is not sufficient to activate the holoenzyme; the low affinity Site A must also be occupied. In rR(R333K), Site A retains its high affinity for cAMP, but Site A cannot bind until the low affinity Site B is occupied. Thus, both mutants, for different reasons, have similar Ka's for activation that are approximately 20-fold higher than that of the wild-type holoenzyme. The double mutant with two defective sites is no worse than either single mutant. (2) Kinetic analysis of cAMP binding showed that the mutation in Site A or B abolishes high affinity cAMP binding to that site and slightly weakens the affinity of the adjacent site for cAMP. (3) In the presence of MgATP, both mutants rapidly form a stable holoenzyme even in the presence of cAMP in contrast to the wild-type R where holoenzyme forms slowly in vitro and requires dialysis. Regarding the mechanism of activation based on these and other mutants and from kinetic data, the following conclusions are reached: Site A provides the major contact site with the C-subunit; Site B is not essential for holoenzyme formation. Occupancy of Site A by cAMP mediates dissociation of the C-subunit. Site A is inaccessible to cAMP in the full length holoenzyme, while Site B is fully accessible. Access of cAMP to Site A is mediated by Site B. Thus Site B not only helps to shield Site A, it also provides the specific signal that "opens up" Site A. Finally, a nonfunctional Site A in the holoenzyme prevents stable binding of cAMP to Site B in the absence of subunit dissociation.
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Affiliation(s)
- F W Herberg
- Department of Chemistry, University of California, San Diego, La Jolla, 92093-0654, USA
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42
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Abstract
(RP)-cAMPS is known to inhibit competitively the cAMP-induced activation of cAMP-dependent protein kinase (PKA). The molecular nature of this inhibition, however, is unknown. By monitoring the intrinsic tryptophan fluorescence of recombinant type I regulatory subunit of PKA under unfolding conditions, a free energy value (delta GDH2O) of 8.23 +/- 0.22 kcal/mol was calculated. The cAMP-free form of the regulatory subunit was less stable with delta GDH2O = 6.04 +/- 0.05 kcal/mol. Native stability was recovered by treatment of the cAMP-free protein with either cAMP or (SP)-cAMPS but not with (RP)-cAMPS. Thus, (RP)-cAMPS binding to the regulatory subunit keeps the protein in a locked conformation, unable to release the catalytic subunit. This finding was further supported by demonstrating that holoenzyme formation was greatly accelerated only when bound cAMP was replaced with (RP)-cAMPS but not with cAMP or (SP)-cAMPS.
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Affiliation(s)
- W R Dostmann
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
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43
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Wild N, Herberg FW, Hofmann F, Dostmann WR. Expression of a chimeric, cGMP-sensitive regulatory subunit of the cAMP-dependent protein kinase type I alpha. FEBS Lett 1995; 374:356-62. [PMID: 7589570 DOI: 10.1016/0014-5793(95)01146-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To study the fluctuations of cGMP in living cells through changes of energy transfer of dissociable fluorescence labeled subunits, we constructed a cGMP-sensitive probe by combining the N-terminus of the type I regulatory subunit of cAMP-dependent protein kinase (PKA) with the cGMP binding sites of cGMP-dependent protein kinase I alpha (PKG). This chimeric regulatory subunit retained PKA-like dimerization and PKG-compatible cGMP binding constants (Kd = 53 nM) for both binding sites. High affinity interaction with the PKA catalytic subunit was verified by Surface Plasmon Resonance (Kd = 3.15 nM). Additionally, the chimera inhibits the formation of wild-type holoenzyme with an apparent Ki of 1.05 nM. Furthermore, cGMP dissociated the mutant holoenzyme with an apparent activation constant of 146 nM. Thus, our construct provides all the requirements needed to investigate changes in intracellular cGMP concentrations.
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Affiliation(s)
- N Wild
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
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44
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Tegge W, Frank R, Hofmann F, Dostmann WR. Determination of cyclic nucleotide-dependent protein kinase substrate specificity by the use of peptide libraries on cellulose paper. Biochemistry 1995; 34:10569-77. [PMID: 7654713 DOI: 10.1021/bi00033a032] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An iterative approach to the a priori determination of the substrate specificity of cAMP- and cGMP-dependent protein kinases (PKA and PKG) by the use of peptide libraries on cellulose paper is described. The starting point of the investigation was an octamer library with the general structure Ac-XXX12XXX, where X represents mixtures of all 20 natural amino acids and 1 and 2 represent individual amino acid residues. The library thus contained all possible 2.56 x 10(10) octamers, divided into 400 sublibraries with defined amino acids 1 and 2 each consisting of 6.4 x 10(7) sequences. After phosphorylation with the kinases in the presence of [gamma-32P]ATP, the sublibrarys Ac-XXXRRXXX and Ac-XXXRKXXX were identified as the best substrates for PKA and PKG, respectively. The second-generation libraries had the structures Ac-XXXRR12X and Ac-XXXRK12X for PKA and PKG and resulted in the most active sequence pools Ac-XXXRRASX and Ac-XXXRKKSX. After delineation of every position in the octameric sequence and extension of the investigation to decameric peptides, the best sequences, Ac-KRAERKASIY and Ac-TQKARKKSNA, were obtained for PKA and PKG, respectively. Promising octameric and decameric peptides were assembled 5 or 10 times each and assayed in order to determine the experimental scatter inherent in the approach. The kinetic data of several octameric and decameric sequences were determined in solution and compared to data for known substrates. The recognition motif of PKA was confirmed by this approach, and a novel substrate sequence for PKG was identified.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W Tegge
- Gesellschaft für Biotechnologische Forschung, Braunschweig, Germany
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45
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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46
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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47
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Herberg FW, Dostmann WR, Zorn M, Davis SJ, Taylor SS. Crosstalk between domains in the regulatory subunit of cAMP-dependent protein kinase: influence of amino terminus on cAMP binding and holoenzyme formation. Biochemistry 1994; 33:7485-94. [PMID: 8003514 DOI: 10.1021/bi00189a057] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The regulatory (R) subunit of cAMP-dependent protein kinase os an asymmetric multidomain protein with a dimerization domain at the N-terminus, an autoinhibitors site, and two cAMP binding domains at the C-terminus. Activation of the tetrameric holoenzyme is mediated by the cooperative binding of cAMP to the two cAMP binding sites. To better understand how the various domains influence each other, the N-terminus (delta 1-91) up to the autoinhibitor site was deleted. Not only did this monomeric deletion mutant, purified from Escherichia coli, still bind cAMP and the catalytic (C) subunit with high affinity, holoenzyme formation was actually accelerated by at least 50-fold. MgATP also was not required for rapid reassociation of (delta 1-91)R(cAMP)2 and C. The Kd(cAMP) and the Ka(cAMP) were similar to those for holoenzyme formed with full-length R; however, cooperatively was lost. Thus the N-terminus, either by inter- or intraprotomer contacts, not only impedes holoenzyme formation but also influences the cooperative binding of cAMP. The 1-91 deletion also renders the remaining fragment resistant to proteolytic degradation. Finally, unlike full-length R, the mutant protein can migrate freely into the nucleus. Surface plasmon resonance studies for the first time enabled direct measurements of the association and dissociation rate constants both for the intact R and for (delta 1-91)R. Both displayed very fast on-rates (1 x 10(-5) M-1 s-1 and 1.1 x 10(-5) M-1 s-1, respectively) and extremely slow off-rates (2.3 x 10(5) M-1 and 4.3 x 10(5) M-1, respectively). Thus, unlike the heat-stable protein kinase inhibitor, the region preceding the autoinhibitor site in R does not contribute in a quantitatively significant way to the high-affinity binding of C.
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Affiliation(s)
- F W Herberg
- Department of Chemistry, University of California, San Diego, La Jolla 92093-0654
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48
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Abstract
A single deletion (delta 1 to 91) mutant of the regulatory subunit of the cAMP dependent protein kinase was crystallized. The crystals are hexagonal P6(1)22 (P6(5)22) with a = b = 88.7 A and c = 179.9 A. The crystals diffract to 3 A resolution. There is one molecule per asymmetric unit.
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Affiliation(s)
- Y Su
- Department of Chemistry, University of California, San Diego, La Jolla 92093-0317
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49
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Dostmann WR, Taylor SS. Identifying the molecular switches that determine whether (Rp)-cAMPS functions as an antagonist or an agonist in the activation of cAMP-dependent protein kinase I. Biochemistry 1991; 30:8710-6. [PMID: 1653606 DOI: 10.1021/bi00099a032] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Previous investigations revealed that under physiological conditions in the presence of MgATP the phosphorothioate analogue of cAMP, (Rp)-cAMPS, is a competitive inhibitor and antagonist for cAMP for cAMP-dependent protein kinases I and II [DeWit et al., (1984) Eur. J. Biochem. 142, 255-260]. For the type I holoenzyme, the antagonist properties of (Rp)-cAMPS are shown here to be absolutely dependent on MgATP. In the absence of MgATP, (Rp)-cAMPS serves as a weak agonist with a Ka of 7.9 microM. The high-affinity binding of MgATP imposes a barrier on cAMP-induced activation of the homoenzyme--a barrier that both cAMP and (Sp)-cAMPS, but not (Rp)-cAMPS, can overcome. In the absence of MgATP, this barrier no longer exists, and (Rp)-cAMPS functions as an agonist. The holoenzyme also was formed with mutant regulatory subunits. Replacing the essential arginine, predicted to bind the exocyclic oxygens of cAMP, in site A with lysine abolishes high-affinity binding of cAMP to site A. The holoenzyme formed with this mutant R-subunit is activated by (Rp)-cAMPS in both the presence and absence of MgATP. These results suggest that the stereospecific requirements for holoenzyme activation involve this guanidinium side chain. Mutations that eliminate the high-affinity binding of MgATP, such as the introduction of an autophosphorylation site in the autoinhibitory domain, also generate a holoenzyme that can be activated by (Rp)-cAMPS. In the case of the type II holoenzyme, (Rp)-cAMPS is an antagonist in both the presence and absence of MgATP, emphasizing distinct roles for MgATP in these two forms of cAMP-dependent protein kinase.
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Affiliation(s)
- W R Dostmann
- Department of Chemistry, University of California, San Diego, La Jolla 92093-0654
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50
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Abstract
The unfolding of the recombinant regulatory subunit of cAMP-dependent protein kinase I was followed by monitoring the intrinsic protein fluorescence. Unfolding proceeds in at least two stages. First, the quenching of fluorescence due to cAMP binding is abolished at relatively low levels of urea (less than 2 M) and is observed as an increase in intensity at 340 nm. The high-affinity binding of cAMP is retained in 3 M urea even though the quenching is lost. The second stage of unfolding, presumably representing unfolding of the polypeptide chain, is seen as a shift in lambda max from 340 to 353 nm. The midpoint concentration, Cm, for this process is 5.0 M. Cyclic AMP binding activity is lost at a half-maximal urea concentration of 3.5 M and precedes the shift in lambda max. Unfolding of the protein in the presence of urea was fully reversible; furthermore, the presence of excess levels of cAMP stabilized the regulatory subunit. A free energy value (delta GDH2O) of 7.1 +/- 0.2 kcal/mol was calculated for the native form of the protein when denaturation was induced with either urea or guanidine hydrochloride. Iodide quenching of tryptophan fluorescence was used to elucidate the number of tryptophan residues accessible during various stages of the unfolding process. In the native cAMP-bound form of the regulatory subunit, only one of the three tryptophans in the regulatory subunit is quenched by iodide while more than two tryptophans can be quenched with iodide in the presence of 3 M urea.
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Affiliation(s)
- D A León
- Department of Biochemistry, University of California, San Diego, La Jolla 92093-0654
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