1
|
Cho S, Park TH. Advances in the Production of Olfactory Receptors for Industrial Use. Adv Biol (Weinh) 2023; 7:e2200251. [PMID: 36593488 DOI: 10.1002/adbi.202200251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 12/11/2022] [Indexed: 01/04/2023]
Abstract
In biological olfactory systems, olfactory receptors (ORs) can recognize and discriminate between thousands of volatile organic compounds with very high sensitivity and specificity. The superior properties of ORs have led to the development of OR-based biosensors that have shown promising potential in many applications over the past two decades. In particular, newly designed technologies in gene synthesis, protein expression, solubilization, purification, and membrane mimetics for membrane proteins have greatly opened up the previously inaccessible industrial potential of ORs. In this review, gene design, expression and solubilization strategies, and purification and reconstitution methods available for modern industrial applications are examined, with a focus on ORs. The limitations of current OR production technology are also estimated, and future directions for further progress are suggested.
Collapse
Affiliation(s)
- Seongyeon Cho
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Tai Hyun Park
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| |
Collapse
|
2
|
Kwon OS, Song HS, Park TH, Jang J. Conducting Nanomaterial Sensor Using Natural Receptors. Chem Rev 2018; 119:36-93. [DOI: 10.1021/acs.chemrev.8b00159] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Oh Seok Kwon
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
- Nanobiotechnology and Bioinformatics (Major), University of Science & Technology (UST), Daejon 34141, Republic of Korea
| | - Hyun Seok Song
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Bioconvergence Analysis, Korea Basic Science Institute (KBSI), Cheongju 28119, Republic of Korea
- Center for Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Tai Hyun Park
- School of Chemical and Biological Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Jyongsik Jang
- School of Chemical and Biological Engineering, Seoul National University, Seoul 08826, Republic of Korea
| |
Collapse
|
3
|
Jain AR, Stradley SH, Robinson AS. The A2aR C-terminus provides improved total and active expression yields for adenosine receptor chimeras. AIChE J 2018. [DOI: 10.1002/aic.16398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Abhinav R. Jain
- Dept. of Chemical and Biomolecular Engineering; Tulane University; New Orleans LA 70118
| | - Steven H. Stradley
- Dept. of Chemical and Biomolecular Engineering; Tulane University; New Orleans LA 70118
| | - Anne S. Robinson
- Dept. of Chemical and Biomolecular Engineering; Tulane University; New Orleans LA 70118
| |
Collapse
|
4
|
Beech J, Saleh L, Frentzel J, Figler H, Corrêa IR, Baker B, Ramspacher C, Marshall M, Dasa S, Linden J, Noren CJ, Kelly KA. Multivalent site-specific phage modification enhances the binding affinity of receptor ligands. Bioconjug Chem 2015; 26:529-36. [PMID: 25692462 DOI: 10.1021/acs.bioconjchem.5b00011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
High-throughput screening of combinatorial chemical libraries is a powerful approach for identifying targeted molecules. The display of combinatorial peptide libraries on the surface of bacteriophages offers a rapid, economical way to screen billions of peptides for specific binding properties and has impacted fields ranging from cancer to vaccine development. As a modification to this approach, we have previously created a system that enables site-specific insertion of selenocysteine (Sec) residues into peptides displayed pentavalently on M13 phage as pIII coat protein fusions. In this study, we show the utility of selectively derivatizing these Sec residues through the primary amine of small molecules that target a G protein-coupled receptor, the adenosine A1 receptor, leaving the other coat proteins, including the major coat protein pVIII, unmodified. We further demonstrate that modified Sec-phage with multivalent bound agonist binds to cells and elicits downstream signaling with orders of magnitude greater potency than that of unconjugated agonist. Our results provide proof of concept of a system that can create hybrid small molecule-containing peptide libraries and open up new possibilities for phage-drug therapies.
Collapse
Affiliation(s)
| | - Lana Saleh
- #Division of Chemical Biology, New England Biolabs, Ipswich, Massachusetts 01938, United States
| | - Julie Frentzel
- #Division of Chemical Biology, New England Biolabs, Ipswich, Massachusetts 01938, United States
| | | | - Ivan R Corrêa
- #Division of Chemical Biology, New England Biolabs, Ipswich, Massachusetts 01938, United States
| | - Brenda Baker
- #Division of Chemical Biology, New England Biolabs, Ipswich, Massachusetts 01938, United States
| | - Caroline Ramspacher
- #Division of Chemical Biology, New England Biolabs, Ipswich, Massachusetts 01938, United States
| | | | | | - Joel Linden
- ⊥La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, United States
| | - Christopher J Noren
- #Division of Chemical Biology, New England Biolabs, Ipswich, Massachusetts 01938, United States
| | | |
Collapse
|
5
|
Kennedy DP, McRobb FM, Leonhardt SA, Purdy M, Figler H, Marshall MA, Chordia M, Figler R, Linden J, Abagyan R, Yeager M. The second extracellular loop of the adenosine A1 receptor mediates activity of allosteric enhancers. Mol Pharmacol 2014; 85:301-9. [PMID: 24217444 PMCID: PMC3913357 DOI: 10.1124/mol.113.088682] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 11/11/2013] [Indexed: 01/26/2023] Open
Abstract
Allosteric enhancers of the adenosine A1 receptor amplify signaling by orthosteric agonists. Allosteric enhancers are appealing drug candidates because their activity requires that the orthosteric site be occupied by an agonist, thereby conferring specificity to stressed or injured tissues that produce adenosine. To explore the mechanism of allosteric enhancer activity, we examined their action on several A1 receptor constructs, including (1) species variants, (2) species chimeras, (3) alanine scanning mutants, and (4) site-specific mutants. These findings were combined with homology modeling of the A1 receptor and in silico screening of an allosteric enhancer library. The binding modes of known docked allosteric enhancers correlated with the known structure-activity relationship, suggesting that these allosteric enhancers bind to a pocket formed by the second extracellular loop, flanked by residues S150 and M162. We propose a model in which this vestibule controls the entry and efflux of agonists from the orthosteric site and agonist binding elicits a conformational change that enables allosteric enhancer binding. This model provides a mechanism for the observations that allosteric enhancers slow the dissociation of orthosteric agonists but not antagonists.
Collapse
Affiliation(s)
- Dylan P Kennedy
- Department of Pharmacology (D.P.K.), Department of Molecular Physiology and Biological Physics (S.A.L., M.P., H.F., M.C., R.F., M.Y.), Cardiovascular Research Center (M.A.M., R.F., M.Y.), Center for Membrane Biology (M.Y.), and Department of Medicine, Division of Cardiovascular Medicine (M.Y.), University of Virginia School of Medicine, Charlottesville, Virginia; the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California (F.M.M., R.A.); and the La Jolla Institute for Allergy and Immunology (J.L.), La Jolla, California
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Orestes P, Osuru HP, McIntire WE, Jacus MO, Salajegheh R, Jagodic MM, Choe W, Lee J, Lee SS, Rose KE, Poiro N, DiGruccio MR, Krishnan K, Covey DF, Lee JH, Barrett PQ, Jevtovic-Todorovic V, Todorovic SM. Reversal of neuropathic pain in diabetes by targeting glycosylation of Ca(V)3.2 T-type calcium channels. Diabetes 2013; 62:3828-38. [PMID: 23835327 PMCID: PMC3806612 DOI: 10.2337/db13-0813] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
It has been established that Ca(V)3.2 T-type voltage-gated calcium channels (T-channels) play a key role in the sensitized (hyperexcitable) state of nociceptive sensory neurons (nociceptors) in response to hyperglycemia associated with diabetes, which in turn can be a basis for painful symptoms of peripheral diabetic neuropathy (PDN). Unfortunately, current treatment for painful PDN has been limited by nonspecific systemic drugs with significant side effects or potential for abuse. We studied in vitro and in vivo mechanisms of plasticity of Ca(V)3.2 T-channel in a leptin-deficient (ob/ob) mouse model of PDN. We demonstrate that posttranslational glycosylation of specific extracellular asparagine residues in Ca(V)3.2 channels accelerates current kinetics, increases current density, and augments channel membrane expression. Importantly, deglycosylation treatment with neuraminidase inhibits native T-currents in nociceptors and in so doing completely and selectively reverses hyperalgesia in diabetic ob/ob mice without altering baseline pain responses in healthy mice. Our study describes a new mechanism for the regulation of Ca(V)3.2 activity and suggests that modulating the glycosylation state of T-channels in nociceptors may provide a way to suppress peripheral sensitization. Understanding the details of this regulatory pathway could facilitate the development of novel specific therapies for the treatment of painful PDN.
Collapse
Affiliation(s)
- Peihan Orestes
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia
| | - Hari Prasad Osuru
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
| | - William E. McIntire
- Department of Pharmacology, University of Virginia Health System, Charlottesville, Virginia
| | - Megan O. Jacus
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
| | - Reza Salajegheh
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
| | - Miljen M. Jagodic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
| | - WonJoo Choe
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
- Department of Anesthesiology and Pain Medicine, InJe University, Ilsan Paik Hospital & College of Medicine, Goyang-City, South Korea
| | - JeongHan Lee
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
- Department of Anesthesiology and Pain Medicine, Busan Paik Hospital, InJe University, College of Medicine, Busan, South Korea
| | - Sang-Soo Lee
- Department of Life Science, Sogang University, Seoul, South Korea
- Interdisciplinary Program of Biotechnology, Sogang University, Seoul, South Korea
| | - Kirstin E. Rose
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
| | - Nathan Poiro
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
| | - Michael R. DiGruccio
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia
| | - Katiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri
| | - Douglas F. Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri
| | - Jung-Ha Lee
- Department of Life Science, Sogang University, Seoul, South Korea
- Interdisciplinary Program of Biotechnology, Sogang University, Seoul, South Korea
| | - Paula Q. Barrett
- Department of Pharmacology, University of Virginia Health System, Charlottesville, Virginia
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
- Department of Neuroscience, University of Virginia Health System, Charlottesville, Virginia
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia
| | - Slobodan M. Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, Virginia
- Department of Neuroscience, University of Virginia Health System, Charlottesville, Virginia
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia
- Corresponding author: Slobodan M. Todorovic,
| |
Collapse
|
7
|
Han YY, Chen WB, Han WY, Wu ZJ, Zhang XM, Yuan WC. Highly Efficient and Stereoselective Construction of Dispiro-[oxazolidine-2-thione]bisoxindoles and Dispiro[imidazolidine-2-thione]bisoxindoles. Org Lett 2012; 14:490-3. [DOI: 10.1021/ol203081x] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Yan-Yan Han
- National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wen-Bing Chen
- National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wen-Yong Han
- National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi-Jun Wu
- National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao-Mei Zhang
- National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei-Cheng Yuan
- National Engineering Research Center of Chiral Drugs, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| |
Collapse
|
8
|
Salom D, Cao P, Sun W, Kramp K, Jastrzebska B, Jin H, Feng Z, Palczewski K. Heterologous expression of functional G-protein-coupled receptors in Caenorhabditis elegans. FASEB J 2011; 26:492-502. [PMID: 22090314 DOI: 10.1096/fj.11-197780] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
New strategies for expression, purification, functional characterization, and structural determination of membrane-spanning G-protein-coupled receptors (GPCRs) are constantly being developed because of their importance to human health. Here, we report a Caenorhabditis elegans heterologous expression system able to produce milligram amounts of functional native and engineered GPCRs. Both bovine opsin [(b)opsin] and human adenosine A(2A) subtype receptor [(h)A(2A)R] expressed in neurons or muscles of C. elegans were localized to cell membranes. Worms expressing these GPCRs manifested changes in motor behavior in response to light and ligands, respectively. With a newly devised protocol, 0.6-1 mg of purified homogenous 9-cis-retinal-bound bovine isorhodopsin [(b)isoRho] and ligand-bound (h)A(2A)R were obtained from C. elegans from one 10-L fermentation at low cost. Purified recombinant (b)isoRho exhibited its signature absorbance spectrum and activated its cognate G-protein transducin in vitro at a rate similar to native rhodopsin (Rho) obtained from bovine retina. Generally high expression levels of 11 native and mutant GPCRs demonstrated the potential of this C. elegans system to produce milligram quantities of high-quality GPCRs and possibly other membrane proteins suitable for detailed characterization.
Collapse
|
9
|
Romero-Fernandez W, Garriga P, Borroto-Escuela DO. Overproduction of human M₃ muscarinic acetylcholine receptor: an approach toward structural studies. Biotechnol Prog 2011; 27:838-45. [PMID: 21548142 DOI: 10.1002/btpr.615] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 11/18/2010] [Indexed: 11/10/2022]
Abstract
Human M(3) muscarinic acetylcholine receptor (M3R), present in both the central and the peripheral nervous system, is involved in several neurodegenerative and autoimmune diseases. Recently, M3R overexpression has been suggested to play a role in certain forms of cancer, showing promise as a new potential pharmacological target. However, the lack of structural information hampered to develop a new potent selective and potent antagonist. We describe here different strategies for overexpressing functional M3R on the perspective of future biophysical studies. To achieve this goal, four tagged M3R genes were engineered and codon optimized. Different heterologous expression systems, including mammalian cells and viral transfection, were employed to overexpress M3R. Although codon optimization resulted in only twofold to threefold increase of M3R expression, we found that epitope tagging of the synthetic M3R, especially with hemagglutinin and Flag epitope tags, could improve M3R expression levels. On the other hand, viral transfection led to a yield of 27 pmol/mg protein that is the highest level reported so far for this receptor subtype in mammalian cells. Taking together several of the strategies used can help increasing M3R expression, not only to start purification efforts but also for secondary structural analysis trial and functional analyses.
Collapse
Affiliation(s)
- Wilber Romero-Fernandez
- Centre de Biotecnologia Molecular, Dept. d'Enginyeria Química, Universitat Politècnica de Catalunya, Terrassa 08222, Spain
| | | | | |
Collapse
|
10
|
Bigler Wang D, Sherman NE, Shannon JD, Leonhardt SA, Mayeenuddin LH, Yeager M, McIntire WE. Binding of β4γ5 by adenosine A1 and A2A receptors determined by stable isotope labeling with amino acids in cell culture and mass spectrometry. Biochemistry 2010; 50:207-20. [PMID: 21128647 DOI: 10.1021/bi101227y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Characterization of G protein βγ dimer isoform expression in different cellular contexts has been impeded by low levels of protein expression, broad isoform heterogeneity, and antibodies of limited specificity, sensitivity, or availability. As a new approach, we used quantitative mass spectrometry to characterize native βγ dimers associated with adenosine A(1):α(i1) and adenosine A(2A):α(S) receptor fusion proteins expressed in HEK-293 cells. Cells expressing A(1):α(i1) were cultured in media containing [(13)C(6)]Arg and [(13)C(6)]Lys and βγ labeled with heavy isotopes purified. Heavy βγ was combined with either recombinant βγ purified from Sf9 cells, βγ purified from the A(2A):α(S) expressed in HEK-293 cells cultured in standard media, or an enriched βγ fraction from HEK-293 cells. Samples were separated by SDS-PAGE, protein bands containing β and γ were excised, digested with trypsin, and separated by HPLC, and isotope ratios were analyzed by mass spectrometry. Three β isoforms, β(1), β(2), and β(4), and seven γ isoforms, γ(2), γ(4), γ(5), γ(7), γ(10), γ(11), and γ(12), were identified in the analysis. β(1) and γ(5) were most abundant in the enriched βγ fraction, and this βγ profile was generally mirrored in the fusion proteins. However, both A(2A):α(S) and A(1):α(i1) bound more β(4) and γ(5) compared to the enriched βγ fraction; also, more β(4) was associated with A(2A):α(S) than A(1):α(i1). Both fusion proteins also contained less γ(2), γ(10), and γ(12) than the enriched βγ fraction. These results suggest that preferences for particular βγ isoforms may be driven in part by structural motifs common to adenosine receptor family members.
Collapse
Affiliation(s)
- Dora Bigler Wang
- Department of Pharmacology, University of Virginia Health System, Charlottesville, 22908, United States
| | | | | | | | | | | | | |
Collapse
|
11
|
Lai WC, Tseng TL, Jian T, Lee TL, Cheng CW, Shieh JC. Construction of Candida albicans Tet-on tagging vectors with a Ura-blaster cassette. Yeast 2010; 28:253-63. [DOI: 10.1002/yea.1833] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 11/07/2010] [Indexed: 11/10/2022] Open
|
12
|
Blethrow JD, Tang C, Deng C, Krutchinsky AN. Modular mass spectrometric tool for analysis of composition and phosphorylation of protein complexes. PLoS One 2007; 2:e358. [PMID: 17406682 PMCID: PMC1832223 DOI: 10.1371/journal.pone.0000358] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Accepted: 03/18/2007] [Indexed: 11/18/2022] Open
Abstract
The combination of high accuracy, sensitivity and speed of single and multiple-stage mass spectrometric analyses enables the collection of comprehensive sets of data containing detailed information about complex biological samples. To achieve these properties, we combined two high-performance matrix-assisted laser desorption ionization mass analyzers in one modular mass spectrometric tool, and applied this tool for dissecting the composition and post-translational modifications of protein complexes. As an example of this approach, we here present studies of the Saccharomyces cerevisiae anaphase-promoting complexes (APC) and elucidation of phosphorylation sites on its components. In general, the modular concept we describe could be useful for assembling mass spectrometers operating with both matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) ion sources into powerful mass spectrometric tools for the comprehensive analysis of complex biological samples.
Collapse
Affiliation(s)
- Justin D. Blethrow
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
| | - Chao Tang
- XProteo Inc, New York, New York, United States of America
| | - Changhui Deng
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Andrew N. Krutchinsky
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| |
Collapse
|
13
|
Ravyn V, Bostwick JR. Functional coupling of the Galpha(olf) variant XLGalpha(olf) with the human adenosine A2A receptor. J Recept Signal Transduct Res 2006; 26:241-58. [PMID: 16818375 DOI: 10.1080/10799890600710592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A recently identified novel Galphaolf variant, XLGalphaolf, is shown to functionally couple to the human adenosine A2A receptor (A2AR). In Sf9 cells expressing A2AR, beta1, and gamma2, co-expression of XLGalphaolf increased NECA-induced [35S]GTPgammaS binding from approximately 130% to 300% of basal levels. Pharmacological characteristics of A2AR ligands on these cells were evaluated by using [3H]ZM241385- and [35S]GTPgammaS- binding assays. The rank order of the equilibrium binding constants (Kd or Ki) of adenosine receptor ligands were [3H]ZM241385 approximately CGS15943 < MRS1220 < < CV1808 approximately NECA < CGS21680 approximately adenosine < IBMECA < HEMADO approximately CPA approximately CCPA. The rank order of EC50 values for agonists were CV1808 approximately NECA < adenosine approximately CGS26180 < IBMECA < HEMADO approximately CPA approximately CCPA. This pharmacology is consistent with the literature for A2AR and suggests that Sf9 cells co-expressing A2AR, beta1, gamma2, and XLGalphaolf could serve as a heterologous expression system for A2AR drug screening.
Collapse
Affiliation(s)
- Vipa Ravyn
- Lead Discovery, AstraZeneca Pharmaceuticals, Wilmington, Delaware 19850, USA
| | | |
Collapse
|
14
|
Ratnala VRP. New tools for G-protein coupled receptor (GPCR) drug discovery: combination of baculoviral expression system and solid state NMR. Biotechnol Lett 2006; 28:767-78. [PMID: 16786240 DOI: 10.1007/s10529-006-9005-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 02/14/2006] [Indexed: 10/24/2022]
Abstract
Biotechnology using molecular biology, biochemistry, biophysics, and computational approaches provides an alternative approach for classical pharmacological screening to look at ligand-receptor interactions and receptor specificity, which should support the design of selective drugs based on detailed structural principles. This review addresses specific approaches to study function, structure and relevance of a major pharmaceutical target, namely the G-Protein Coupled Receptors (GPCRs). The main aim of this review has been to exploit and combine GPCR over-expression in a baculoviral expression system with solid-state MAS NMR (ssNMR) approaches for the elucidation of electronic structures of the coordinating ligands/drugs and their modes of interactions with the GPCRs. This review summarizes the approaches, possible future experiments and developments using the above combination of tools for GPCR drug discovery.
Collapse
Affiliation(s)
- Venkata R P Ratnala
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, P.O. Box 9502, 2300 RALeiden, The Netherlands.
| |
Collapse
|
15
|
Akermoun M, Koglin M, Zvalova-Iooss D, Folschweiller N, Dowell SJ, Gearing KL. Characterization of 16 human G protein-coupled receptors expressed in baculovirus-infected insect cells. Protein Expr Purif 2006; 44:65-74. [PMID: 15951199 DOI: 10.1016/j.pep.2005.04.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2005] [Revised: 04/21/2005] [Accepted: 04/24/2005] [Indexed: 10/25/2022]
Abstract
Understanding the three-dimensional structure of G protein-coupled receptors (GPCRs) has been limited by the technical challenges associated with expression, purification, and crystallization of membrane proteins, and their low abundance in native tissue. In the first large-scale comparative study of GPCR protein production using recombinant baculovirus, we report the characterization of 16 human receptors. The GPCRs were produced in three insect cell lines and functional protein levels monitored over 72 h using radioligand binding assays. Different GPCRs exhibited widely different expression levels, ranging from less than 1 pmol receptor/mg protein to more than 250 pmol/mg. No single set of conditions was suitable for all GPCRs, and large differences were seen for the expression of individual GPCRs in different cell lines. Closely related GPCRs did not share similar expression profiles; however, high expression (greater than 20 pmol/mg) was achieved for over half the GPCRs in our study. Overall, the levels of protein production compared favourably to other published systems.
Collapse
Affiliation(s)
- Malika Akermoun
- Gene Expression and Protein Biochemistry, GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, UK
| | | | | | | | | | | |
Collapse
|
16
|
Marathe GK, Johnson C, Billings SD, Southall MD, Pei Y, Spandau D, Murphy RC, Zimmerman GA, McIntyre TM, Travers JB. Ultraviolet B Radiation Generates Platelet-activating Factor-like Phospholipids underlying Cutaneous Damage. J Biol Chem 2005; 280:35448-57. [PMID: 16115894 DOI: 10.1074/jbc.m503811200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ultraviolet B light (UVB) causes cutaneous inflammation and cell death, but the agents responsible are not defined. These studies examined the role of the platelet-activating factor (PAF) signaling system in UVB-mediated effects. Expression of the PAF receptor in the PAF receptor-negative epidermoid cell line KB augmented apoptosis in response to UVB irradiation. Overexpression of the PAF receptor in primary human keratinocytes also enhanced UVB-mediated apoptosis in vitro, and it enhanced apoptosis in an in vivo model of human keratinocytes grafted onto severe combined immune-deficient (SCID) mice. To define the mechanism by which UVB activates the PAF receptor, we used mass spectrometry to demonstrate significant amounts of the C4 PAF analogs 1-alkyl-2-(butanoyl and butenoyl)-sn-glycero-3-phosphocholine, as well as native PAF in an epidermal cell line after UVB irradiation. Supplementing the cells with the precursor phospholipid 1-hexadecyl-2-arachidonoyl-sn-glycero-3-phosphocholine (HAPC) increased the amount of C4 PAF analogs recovered after UVB exposure. We irradiated HAPC directly and found, even in the absence of a photosensitizer, fragmentation to C4-PAF receptor ligands. We conclude UVB photo-oxidizes cellular phospholipids, creating PAF analogs that stimulate the PAF receptor to induce further PAF synthesis and apoptosis. PAF signaling may participate in the cutaneous inflammation that occurs during photo-aggravated dermatoses.
Collapse
Affiliation(s)
- Gopal K Marathe
- Human Molecular Biology and Genetics Program, University of Utah, Salt Lake City 84112-5330, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Derbyshire ZE, Halfter UM, Heimark RL, Sy TH, Vaillancourt RR. Angiotensin II stimulated transcription of cyclooxygenase II is regulated by a novel kinase cascade involving Pyk2, MEKK4 and annexin II. Mol Cell Biochem 2005; 271:77-90. [PMID: 15881658 DOI: 10.1007/s11010-005-5386-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although it is known that MEKK4 regulates MKK6, and p38 MAP kinase, extracellular stimuli that activate the serine/threonine kinase, MEKK4, are unknown. The aim of this study was then to identify stimuli that regulate MEKK4. By using recombinant MEKK4, as bait to attract interacting proteins, the calcium binding protein, annexin II, was identified by mass spectrometry as interacting with MEKK4, suggesting that MEKK4 might be regulated by calcium. A calcium-dependent interaction between MEKK4 and annexin II was observed when MEKK4 was immunoprecipitated from rat aortic smooth muscle cells that were treated with angiotensin II. Additional studies using recombinant MEKK4 in a Far-Western immunoblot identified a protein of 120 kDa as interacting directly with MEKK4. Prior studies indicated that MEKK4 was phosphorylated on tyrosine in vivo, and in fact, Pyk2 interacts with MEKK4 in an angiotensin II dependent manner in rat aortic smooth muscle cells. Pyk2 phosphorylates MEKK4 in vitro and Pyk2-dependent phosphorylation further regulates MEKK4-dependent phosphorylation of MKK6. Finally, dominant-negative MEKK4 inhibits angiotensin II mediated transcription of a luciferase reporter construct containing the cyclooxygenase II promoter, demonstrating that MEKK4 functions in a calcium-dependent manner as a substrate for Pyk2 and regulates transcription of cyclooxygenase II.
Collapse
Affiliation(s)
- Zachary E Derbyshire
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | | | | | | | | |
Collapse
|
18
|
Hoffmann C, Soltysiak K, West PL, Jacobson KA. Shift in purine/pyrimidine base recognition upon exchanging extracellular domains in P2Y 1/6 chimeric receptors. Biochem Pharmacol 2005; 68:2075-86. [PMID: 15476678 PMCID: PMC4371599 DOI: 10.1016/j.bcp.2004.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2004] [Accepted: 07/09/2004] [Indexed: 10/26/2022]
Abstract
P2Y receptors are G protein-coupled receptors stimulated by extracellular nucleotides. Both the P2Y(1) and the P2Y(6) receptors are preferentially activated by nucleoside 5'-diphosphates, but favor different base moieties. In the case of the P2Y(1) receptor the preferred base is adenine, while the P2Y(6) receptor is activated by uracil nucleotides. To identify potential amino acid domains that interact with the base moiety, we used a chimeric receptor approach, employing the human P2Y(1) receptor as core structure to investigate the role in receptor activation of extracellular loops (ELs) and transmembrane domains (TMs) of the rat P2Y(6) receptor. The chimeric receptors were expressed in COS-7 cells and measured for stimulation of phospholipase C (PLC) induced by the potent P2Y(1) receptor agonist 2-MeSADP or the potent P2Y(6) receptor agonist UDP. Replacement of the N-terminus or EL2 resulted in low ( approximately 50 microM) potency of the agonist 2-MeSADP, thus confirming the importance of EL2 in ligand recognition. Upon replacement of several regions, the potency of the P2Y(1) agonist 2-MeSADP was either 1-2 microM (N-terminus and EL1, or EL1 and EL3) or 72 microM (N-terminus and EL3). Concurrent replacement of three regions (N-terminus, EL1, and EL3) completely precluded activation by 2-MeSADP. Our study identified domains of the P2Y(6) receptor that contribute to receptor activation by UDP and hence seem to be involved in uracil recognition. Upon replacement with extracellular domains of the P2Y(6) receptor sequence we observed a trend toward gain of receptor-induced PLC activation by UDP, for example, in the chimera containing replacements of both the N-terminus and EL1. Exchange of three receptor domains led to a construct with an EC(50) value for UDP of 19 microM and a maximal inositol phosphate accumulation similar to the native P2Y(6) receptor. Within receptor constructs of combined domain exchanges the additional substitution of Tyr(110) by the corresponding Asn from the P2Y(6) receptor showed a significant increase for activation by UDP, but only when combined with the N-terminal domain and TM1. The residue Tyr(110) was identified to play an important role in the recognition of the nucleobase in the P2Y(1) and P2Y(6) receptors.
Collapse
Affiliation(s)
| | | | | | - Kenneth A. Jacobson
- Corresponding author. Tel.: +1 301 496 9024; fax: +1 301 480 8422. (K.A. Jacobson)
| |
Collapse
|
19
|
Day YJ, Huang L, Ye H, Linden J, Okusa MD. Renal ischemia-reperfusion injury and adenosine 2A receptor-mediated tissue protection: role of macrophages. Am J Physiol Renal Physiol 2004; 288:F722-31. [PMID: 15561971 DOI: 10.1152/ajprenal.00378.2004] [Citation(s) in RCA: 218] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of monocytes/macrophages in the pathogenesis of ischemia-reperfusion injury (IRI) is unknown. We sought to determine whether activation of macrophage adenosine 2A (A(2A)) receptors (A(2A)Rs) mediates tissue protection. We subjected C57Bl/6 mice infused with clodronate [dichloromethylene bisphosphonate (Cl(2)MBP)] to IRI (32 min of ischemia followed by 24 h of reperfusion) to deplete them of macrophages. IRI induced an elevation of plasma creatinine that was reduced with Cl(2)MBP (26% of control). Adoptive transfer of murine RAW 264.7 cells reconstituted injury, an effect blocked significantly by A(2A) agonists (27% of plasma creatinine from mice reconstituted with macrophages). Macrophages subjected to A(2A) knockout by small interfering RNA were adoptively transferred to macrophage-depleted mice and reconstituted injury (110% of control mice); however, the increase in plasma creatinine was blocked by A(2A) agonists (20% of vehicle treatment). Finally, the A(2A) agonist effect on IRI was blocked in macrophage-depleted A(2A)-knockout mice reconstituted with wild-type RAW 264.7 cells. RNase protection assays 24 h after IRI demonstrated that macrophages are required for IL-6 and TGF-beta mRNA induction. However, A(2A) agonist-mediated tissue protection is independent of IL-6 and TGF-beta mRNA. We conclude that the full extent of IRI requires macrophages and that A(2A) agonist-mediated tissue protection is independent of activation of macrophage A(2A)Rs.
Collapse
Affiliation(s)
- Yuan-Ji Day
- Div. of Nephrology, Box 133, Univ. of Virginia Health System, Charlottesville, VA 22908, USA
| | | | | | | | | |
Collapse
|
20
|
Figler H, Olsson RA, Linden J. Allosteric enhancers of A1 adenosine receptors increase receptor-G protein coupling and counteract Guanine nucleotide effects on agonist binding. Mol Pharmacol 2004; 64:1557-64. [PMID: 14645687 DOI: 10.1124/mol.64.6.1557] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endogenous ligands of G protein-coupled receptors bind to orthosteric sites that are topologically distinct from allosteric sites. Certain aminothiophenes such as (2-amino-4,5-dimethyl-3-thienyl)-[3-(trifluromethyl)-phenyl]-methanone (PD81,723) and 2-amino-4,5,6,7-tetrahydro-benzo[b]thiophen-3-yl)-biphenyl-4-yl-methanone (ATL525) are positive allosteric regulators, or enhancers, of the human A1 adenosine receptor (A1AR). In equilibrium binding assays, 125I-N6-aminobenzyladenosine (125I-ABA) binds to two affinity states of A1AR with KD-high (0.33 microM) and KD-low ( approximately 10 nM). Enhancers have little effect on KD-high but convert all A1AR binding sites to the high-affinity state. Enhancers decrease the potency of guanosine 5'-O-(3-thio)triphosphate (GTPgammaS) as an inhibitor of agonist binding by 100-fold and increase agonist-stimulated guanine nucleotide exchange. The association of 125I-ABA to high-affinity receptors on Chinese hamster ovary (CHO)-hA1 membranes does not follow theoretical single-site association kinetics but is approximated by a bi-exponential equation with t1/2 values of 1.85 and 12.8 min. Allosteric enhancers selectively increase the number of slow binding sites, possibly by stabilizing newly formed receptor-G protein complexes. A new rapid assay method scores enhancer activity on a scale from 0 to 100 based on their ability to prevent the rapid dissociation of 125I-ABA from A1AR in response to GTPgammaS. Compared with PD81,723, ATL525 (100 microM) scores higher (27 versus 79) and has less antagonist activity. ATL525 functionally enhances A1 signaling to inhibit cAMP accumulation in CHO-hA1 cells. These data suggest that simultaneously binding orthosteric and allosteric enhancer ligands convert the A1AR from partly to fully coupled to G proteins and prevents rapid uncoupling upon binding of GTPgammaS.
Collapse
Affiliation(s)
- Heidi Figler
- MR5 Box 801394, Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
| | | | | |
Collapse
|
21
|
Uberti MA, Hall RA, Minneman KP. Subtype-Specific Dimerization of α1-Adrenoceptors: Effects on Receptor Expression and Pharmacological Properties. Mol Pharmacol 2003; 64:1379-90. [PMID: 14645668 DOI: 10.1124/mol.64.6.1379] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The potential role of dimerization in controlling the expression and pharmacological properties of alpha1-adrenoceptor subtypes was examined using coimmunoprecipitation of epitope-tagged receptors. Human alpha1-adrenoceptor subtypes (alpha1A, alpha1B, alpha1D) were tagged at their amino-termini with Flag or hemagglutinin epitopes and transfected into human embryonic kidney 293 cells. Homodimerization of all three subtypes was observed by coimmunoprecipitation of receptors with different tags and was not altered by norepinephrine treatment. Heterodimer formation between hemagglutinin-tagged alpha1B-adrenoceptors and Flag-tagged alpha1A- or alpha1D-adrenoceptors was also observed. However, no alpha1A/alpha1D-adrenoceptor heterodimers were observed, suggesting that dimerization is subtype-specific. The extent of heterodimerization was also unaltered by norepinephrine treatment. alpha1-Adrenoceptor truncation mutants lacking carboxyl or amino-terminal sequences formed homo- and heterodimers similarly to full-length receptors, suggesting that these domains play little or no role in dimerization. Biotinylation with a membrane-impermeable agent showed that monomers and homo- and hetero-oligomers of all three subtypes are expressed on the cell surface. Radioligand binding studies showed that heterodimerization did not alter the affinity of alpha1-adrenoceptors for norepinephrine, prazosin, or subtype-selective antagonists, suggesting that dimerization does not result in pharmacologically distinct subtypes. However, coexpression of alpha1B-adrenoceptors significantly increased both binding site density and protein expression of alpha1A- and alpha1D-adrenoceptors, and increased cell surface expression of alpha1D-adrenoceptors, suggesting a functional role for heterodimerization. Conversely, coexpression of alpha1A-with alpha1D-adrenoceptors, which did not heterodimerize, had no effect on receptor density or protein. These studies demonstrate subtype-selective heterodimerization of alpha1-adrenoceptors, which does not change their pharmacological properties but seems to have functional consequences in regulating receptor expression and trafficking.
Collapse
Affiliation(s)
- Michelle A Uberti
- Department of Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322, USA
| | | | | |
Collapse
|
22
|
Massotte D. G protein-coupled receptor overexpression with the baculovirus-insect cell system: a tool for structural and functional studies. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1610:77-89. [PMID: 12586382 DOI: 10.1016/s0005-2736(02)00720-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
G protein-coupled receptors, whose topology shows seven transmembrane domains, form the largest known family of receptors involved in higher organism signal transduction. These receptors are generally of low natural abundance and overexpression is usually a prerequisite to their structural or functional characterisation. The baculovirus-insect cell system constitutes a versatile tool for the maximal production of receptors. This heterologous expression system also provides interesting alternatives for receptor functional studies in a well-controlled cellular context.
Collapse
Affiliation(s)
- Dominique Massotte
- Laboratoire de Biologie et Génomique Structurales, UMR 7104, IGBMC, 1 rue Laurent Fries, BP 10142, F-67404 Illkirch Cedex, France.
| |
Collapse
|
23
|
Abstract
To facilitate purification and structural characterization, the CB2 cannabinoid receptor is expressed in methylotrophic yeast Pichia pastoris. The expression plasmids were constructed in which the CB2 gene is under the control of the highly inducible promoter of P. pastoris alcohol oxidase 1 gene. A c-myc epitope and a hexahistidine tag were introduced at the C-terminal of the CB2 to permit easy detection and purification. In membrane preparations of CB2 gene transformed yeast cells, Western blot analysis detected the expression of CB2 proteins. Radioligand binding assays demonstrated that the CB2 receptors expressed in P. pastoris have a pharmacological profile similar to that of the receptors expressed in mammalian systems. Furthermore, the epitope-tagged receptor was purified by metal chelating chromatography and the purified CB2 preparations were subjected to digestion by trypsin. MALDI/TOF mass spectrometry analysis of the peptides extracted from tryptic digestions detected 14 peptide fragments derived from the CB2 receptor. ESI mass spectrometry was used to sequence one of these peptide fragments, thus, further confirming the identity of the purified receptor. In conclusion, these data demonstrated for the first time that epitope-tagged, functional CB2 cannabinoid receptor can be expressed in P. pastoris for purification.
Collapse
Affiliation(s)
- Wenke Feng
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40292, USA
| | | | | | | |
Collapse
|
24
|
Vicentic A, Robeva A, Rogge G, Uberti M, Minneman KP. Biochemistry and pharmacology of epitope-tagged alpha(1)-adrenergic receptor subtypes. J Pharmacol Exp Ther 2002; 302:58-65. [PMID: 12065700 DOI: 10.1124/jpet.302.1.58] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Human alpha(1A)-, alpha(1B)-, and alpha(1D)-adrenergic receptors were tagged at their amino termini with FLAG epitopes and stably expressed in human embryonic kidney (HEK)293 cells. Tagged receptors demonstrated a wild-type pharmacology and mobilization of intracellular Ca(2+). After solubilization and immunoprecipitation, monomers, dimers, and trimers of each subtype were apparent on Western blots. Further denaturation with 6 M urea reduced most oligomers to monomers. Deglycosylation reduced the molecular size of alpha(1A)-, and to a lesser extent alpha(1B)- and alpha(1D)-adrenergic receptors. Radioligand binding site density was highest for alpha(1A)- and much lower for alpha(1B)- and alpha(1D)-adrenergic receptors, but did not correlate with protein expression. Commercial anti-alpha(1)-adrenergic receptor antibodies did not recognize the tagged receptors in Western blots of cell lysates, and substantial cross-reactivity was still observed after solubilization and immunoprecipitation. Surprisingly, only receptor monomers were apparent after photoaffinity labeling with (125)I-arylazidoprazosin, and the intensity of photoaffinity-labeling correlated with the density of radioligand binding sites. We conclude that epitope-tagged alpha(1)-adrenergic receptors exist as both monomers and oligomers in HEK293 cells, but there is substantial discrepancy between protein and binding site expression. Because only monomers are detected by photoaffinity labeling, dimers and trimers observed on Western blots may be pharmacologically inactive.
Collapse
Affiliation(s)
- Aleksandra Vicentic
- Department of Pharmacology, 5017 Rollins Research Center, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322, USA
| | | | | | | | | |
Collapse
|
25
|
Murphree LJ, Marshall MA, Rieger JM, MacDonald TL, Linden J. Human A(2A) adenosine receptors: high-affinity agonist binding to receptor-G protein complexes containing Gbeta(4). Mol Pharmacol 2002; 61:455-62. [PMID: 11809871 DOI: 10.1124/mol.61.2.455] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Agonists bind with higher affinity to G protein-coupled heptahelical receptors than to uncoupled receptors. Recombinant A(1) and A(3) adenosine receptors couple well to G(i/o), but recombinant human A(2A) adenosine receptors (hA(2A)AR) couple poorly to G(s) and bind agonists with K(i) values in binding assays that are much higher than ED(50) values for functional responses such as coronary dilation and inhibition of neutrophil oxidative burst. In this study, we produced hA(2A)AR-G protein complexes in membranes derived from Sf9 cells quadruply infected with receptors and heterotrimeric G protein subunits. The composition of G(beta) markedly influences coupling such that A(2A)AR-alpha(s)beta(1)gamma(2) are 8 +/- 2% coupled whereas equivalently expressed A(2A)AR-alpha(s)beta(4)gamma(2) are 40 +/- 2% coupled. Hence, we were able for the first time to accurately measure high-affinity agonist binding to hA(2A)AR. The agonist 2-[2-(4-amino-3-[(125)I]iodophenyl)ethylamino]adenosine binds to coupled and uncoupled hA(2A)AR with K(D) values of 0.46 nM and 26 nM, respectively, a difference in affinity of 57-fold. The addition of GTPgammaS converts all receptors to the low-affinity state. A(2A)AR coupling does not influence binding of antagonists including, (125)I-4-(2-[7-amino-2-[2-furyl][1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl-amino]ethyl)phenol ((125)I-ZM241385), K(D) = 0.5 nM. Based on a comparison of high-affinity binding sites, N(6)-3-iodo-2-chlorobenzyladenosine-5'-N-methyluronamide is only 8-fold A(3) selective (A(2A Ki, H) = 18.3 +/- 3.2 nM; A(3 Ki, H) = 2.4 +/- 0.3 nM) and 2-chloro-N(6)-cyclopentyladenosine is only 33-fold A(1) selective (A(2A Ki, H) = 11.0 +/- 1.9; A(1 Ki, H) = 0.3 +/- 0.1). We conclude that recombinant hA(2A)AR can form a high-affinity receptor-G protein complex with alpha(s)beta(4)gamma(2) that is useful for determining receptor selectivity.
Collapse
Affiliation(s)
- Lauren J Murphree
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | | | | | | | | |
Collapse
|
26
|
Weiss HM, Grisshammer R. Purification and characterization of the human adenosine A(2a) receptor functionally expressed in Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:82-92. [PMID: 11784301 DOI: 10.1046/j.0014-2956.2002.02618.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The adenosine A(2a) receptor belongs to the seven transmembrane helix G-protein-coupled receptor family, is abundant in striatum, vasculature and platelets and is involved in several physiological processes such as blood pressure regulation and protection of cells during anoxia. For structural and biophysical studies we have expressed the human adenosine A(2a) receptor (hA2aR) at high levels inserted into the Escherichia coli inner membrane, and established a purification scheme. Expression was in fusion with the periplasmic maltose-binding protein to levels of 10-20 nmol of receptor per L of culture, as detected with the specific antagonist ligand [(3)H]ZM241385. As the receptor C-terminus was proteolyzed upon solubilization, a protease-resistant but still functional receptor was created by truncation to Ala316. Addition of the sterol, cholesteryl hemisuccinate, allowed a stable preparation of functional hA2aR solubilized in dodecylmaltoside to be obtained, and, increased the stability of the receptor solubilized in other alkylmaltosides. Purification to homogeneity was achieved in three steps, including ligand affinity chromatography based on the antagonist xanthine amine congener. The purified hA2aR fusion protein bound [(3)H]ZM241385 with a K(d) of 0.19 nm and an average B(max) of 13.7 nmol x mg(-1) that suggests 100% functionality. Agonist affinities for the purified solubilized receptor were higher than those for the membrane-bound form. Sufficient pure, functional hA2aR can now be prepared regularly for structural studies.
Collapse
Affiliation(s)
- H Markus Weiss
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK.
| | | |
Collapse
|
27
|
Hamdan FF, Abramovitz M, Mousa A, Xie J, Durocher Y, Ribeiro P. A novel Schistosoma mansoni G protein-coupled receptor is responsive to histamine. Mol Biochem Parasitol 2002; 119:75-86. [PMID: 11755188 DOI: 10.1016/s0166-6851(01)00400-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new cDNA was cloned from the bloodfluke, Schistosoma mansoni and shown to encode a protein with structural characteristics of a biogenic amine G protein-coupled receptor (GPCR). At the amino acid level, the parasite receptor (SmGPCR) shared about the same level of sequence homology (approximately 30%) with all major types of amine GPCRs and could not be identified on the basis of sequence. SmGPCR exhibited several nonconservative substitutions at key GPCR positions, including an unusual asparagine substitution (Asn(111)) for the highly conserved aspartate of transmembrane (TM) 3. The full-length SmGPCR cDNA was double-tagged with N-terminal FLAG and C-terminal hexahistidine epitopes, and was codon-optimized for expression in cultured HEK293 and COS7 cells. In situ immunofluorescence analyses targeting the two N- and C-terminal epitopes demonstrated that the modified SmGPCR was expressed at high level in mammalian cells and assumed a typical GPCR topology, the N-terminus being extracellular and the C-terminus intracellular. Functional activity assays revealed that SmGPCR was responsive to histamine, which caused a dose-dependent elevation in intracellular Ca2+ (EC50=0.54+/-0.05 microM). An Asn(111)-->Asp mutation had no effect on the responsiveness to histamine, suggesting that SmGPCR does not require the TM3 aspartate for agonist activation, in contrast to most amine GPCRs. None of the other monoamines tested had any significant effect on receptor activity, using assays that measured both Ca2+- and cAMP-mediated signaling. The results suggest that SmGPCR is a novel structural class of histamine receptor that may be unique to flatworms.
Collapse
Affiliation(s)
- Fadi F Hamdan
- Institute of Parasitology, McGill University, 21,111 Lakeshore Road, Que., H9X 3V9, Ste. Anne de Bellevue, Canada
| | | | | | | | | | | |
Collapse
|
28
|
Hoffmann M, Verzijl D, Lundstrom K, Simmen U, Alewijnse AE, Timmerman H, Leurs R. Recombinant Semliki Forest virus for over-expression and pharmacological characterisation of the histamine H(2) receptor in mammalian cells. Eur J Pharmacol 2001; 427:105-14. [PMID: 11557261 DOI: 10.1016/s0014-2999(01)01264-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We describe the use of recombinant Semliki Forest virus (SFV) vectors for efficient expression of the rat histamine H(2) (rH(2)) receptor in COS-7 (African green monkey kidney cells) cells. Recombinant SFV-infected COS-7 cells express the histamine rH(2) receptor in a time-dependent fashion with a maximum expression level of 50 pmol mg(-1) after 40 h. SFV-mediated histamine rH(2) receptor expression shows similar pharmacological properties as the receptor expressed transiently or stably in mammalian cells. In addition, we demonstrate the pharmacological and functional characterisation of the D(115)N mutated histamine rH(2) receptor. It has been shown that the D(115)N mutation renders the receptor constitutively active and structurally unstable. The rapid onset of and high maximal expression levels obtained from SFV-infected COS-7 cells enabled us to characterise this mutant receptor. We prove that recombinant SFV vectors are powerful tools for heterologous expression of G-protein-coupled receptors and that one can achieve both the high-level gene expression described for baculovirus-infected insect cells and the use of mammalian cells as hosts.
Collapse
Affiliation(s)
- M Hoffmann
- Leiden/Amsterdam Centre for Drug Research, Division of Medicinal Chemistry, Vrije Universiteit, FEW, De Boelelaan 1083, 1081 HV Amsterdam, Netherlands
| | | | | | | | | | | | | |
Collapse
|
29
|
Peirce SM, Skalak TC, Rieger JM, Macdonald TL, Linden J. Selective A(2A) adenosine receptor activation reduces skin pressure ulcer formation and inflammation. Am J Physiol Heart Circ Physiol 2001; 281:H67-74. [PMID: 11406470 DOI: 10.1152/ajpheart.2001.281.1.h67] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of A(2A) adenosine receptors (A(2A)-AR) by ATL-146e (formerly DWH-146e) prevents inflammatory cell activation and adhesion. Recurrent ischemia-reperfusion (I/R) of the skin results in pressure ulcer formation, a major clinical problem. ATL-146e was evaluated in a novel reproducible rat model of pressure ulcer. A 9-cm(2) region of dorsal rat skin was cyclically compressed at 50 mmHg using a surgically implanted metal plate and an overlying magnet to generate reproducible tissue necrosis. Osmotic minipumps were implanted into 24 rats divided into four equal groups to infuse vehicle (control), ATL-146e (0.004 microg x kg(-1) x min(-1)), ATL-146e plus an equimolar concentration of A(2A) antagonist, ZM-241385, or ZM-241385 alone. Each group received 10 I/R cycles. In non-I/R-treated skin, ATL-146e has no effect on blood flow. I/R-treated skin of the ATL-146e group compared with the vehicle group had 65% less necrotic area, 31% less inhibition of average skin blood flow, and fewer extravasated leukocytes (23 +/- 3 vs. 49 +/- 6 per 500 microm(2)). These data suggest that ATL-146e, acting via an A(2A)-AR, reduces leukocyte infiltration and is a potent prophylactic for I/R injury in skin.
Collapse
Affiliation(s)
- S M Peirce
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, USA
| | | | | | | | | |
Collapse
|
30
|
McIntire WE, MacCleery G, Garrison JC. The G protein beta subunit is a determinant in the coupling of Gs to the beta 1-adrenergic and A2a adenosine receptors. J Biol Chem 2001; 276:15801-9. [PMID: 11278863 DOI: 10.1074/jbc.m011233200] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The signaling specificity of five purified G protein betagamma dimers, beta(1)gamma(2), beta(2)gamma(2), beta(3)gamma(2), beta(4)gamma(2), and beta(5)gamma(2), was explored by reconstituting them with G(s) alpha and receptors or effectors in the adenylyl cyclase cascade. The ability of the five betagamma dimers to support receptor-alpha-betagamma interactions was examined using membranes expressing the beta(1)-adrenergic or A2a adenosine receptors. These receptors discriminated among the defined heterotrimers based solely on the beta isoform. The beta(4)gamma(2) dimer demonstrated the highest coupling efficiency to either receptor. The beta(5)gamma(2) dimer coupled poorly to each receptor, with EC(50) values 40-200-fold higher than those observed with beta(4)gamma(2). Strikingly, whereas the EC(50) of the beta(1)gamma(2) dimer at the beta(1)-adrenergic receptor was similar to beta(4)gamma(2), its EC(50) was 20-fold higher at the A2a adenosine receptor. Inhibition of adenylyl cyclase type I (AC1) and stimulation of type II (AC2) by the betagamma dimers were measured. betagamma dimers containing Gbeta(1-4) were able to stimulate AC2 similarly, and beta(5)gamma(2) was much less potent. beta(1)gamma(2), beta(2)gamma(2), and beta(4)gamma(2) inhibited AC1 equally; beta(3)gamma(2) was 10-fold less effective, and beta(5)gamma(2) had no effect. These data argue that the beta isoform in the betagamma dimer can determine the specificity of signaling at both receptors and effectors.
Collapse
Affiliation(s)
- W E McIntire
- Department of Pharmacology, University of Virginia Health System, Charlottesville, Virginia 22908, USA
| | | | | |
Collapse
|
31
|
Dawson ES, Wells JN. Determination of amino acid residues that are accessible from the ligand binding crevice in the seventh transmembrane-spanning region of the human A(1) adenosine receptor. Mol Pharmacol 2001; 59:1187-95. [PMID: 11306703 DOI: 10.1124/mol.59.5.1187] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The substituted-cysteine accessibility method (SCAM) was applied to transmembrane span seven of the human A(1) adenosine receptor (hA(1)AR) to reveal a subset of amino acids that are exposed to the ligand-binding crevice. The SCAM approach involved a systematic probe of receptor structure by individual substitutions of residues K265 (7.30) to R296 (7.61) with cysteine. In most cases, hA(1)AR substituted-cysteine mutant membranes displayed antagonist dissociation binding constants that did not differ significantly from wild-type (WT). Radioligand binding assays were used to compare cell membranes that were treated with hydrophilic, sulfhydryl-specific methanethiosulfonate derivatives with control cell membranes. Position H278 was previously reported to be required for A(1)AR ligand binding; however, that report did not establish that H278 represents a contact point for ligands. Cysteine-substitution at H278 yields membrane preparations with greatly decreased receptor density compared with WT membranes from cells in the same transfection experiment. However, H278C membranes retain a measurable fraction of antagonist binding. This observation allows for the investigation of binding-crevice accessibility at position 278 and suggests that H278 may not be required for binding of antagonist ligands. Our data reveal the binding-crevice accessibility of residues T270 (7.35), A273 (7.38), I274 (7.39), T277 (7.42), H278 (7.43), N284 (7.49), and Y288 (7.53) in the hA(1)AR. These data are consistent with the high-resolution structure of bovine rhodopsin that features three alpha-helical turns in this region that are interrupted by an elongated, nonhelical structure from positions 7.43 to 7.48 in the primary amino acid sequence.
Collapse
Affiliation(s)
- E S Dawson
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | | |
Collapse
|
32
|
Krishnan G, Morabito MA, Moczydlowski E. Expression and characterization of Flag-epitope- and hexahistidine-tagged derivatives of saxiphilin for use in detection and assay of saxitoxin. Toxicon 2001; 39:291-301. [PMID: 10978747 DOI: 10.1016/s0041-0101(00)00127-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Saxiphilin is a plasma protein from the bullfrog (Rana catesbiana) that binds saxitoxin (STX), a causative agent of paralytic shellfish poisoning. Saxiphilin is homologous to transferrin and consists of two internally homologous domains called the N-lobe and the C-lobe. STX binds to a single site in the C-lobe of saxiphilin. In this study, cloned genes coding for recombinant saxiphilin and C-lobe saxiphilin were modified to contain two tandemly located affinity tags, Flag epitope (DYKDDDDK) and His(6) (HHHHHH), at the protein C-terminus and were expressed in cultured insect cells using baculovirus vectors. Both tagged proteins are readily detected on immunoblots by anti-Flag monoclonal antibody. Flag-His(6)-tagged saxiphilin was purified to homogeneity using Ni(2+)-chelate affinity chromatography and Heparin Sepharose chromatography. Equilibrium analysis of [3H]STX binding to tagged saxiphilin and tagged C-lobe saxiphilin gave K(D) values of 0.75 and 2.7 nM, respectively. Flag-His(6)-tagged saxiphilin was also utilized in a microtiter well solid-phase assay with Reacti-bind metal chelate plates to measure [3H]STX binding and binding competition by unlabeled STX. Such Flag-His(6)-tagged derivatives of saxiphilin have many possible applications in the assay of STX and related toxinological research.
Collapse
Affiliation(s)
- G Krishnan
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8066, USA
| | | | | |
Collapse
|
33
|
Scholl DJ, Wells JN. Serine and alanine mutagenesis of the nine native cysteine residues of the human A(1) adenosine receptor. Biochem Pharmacol 2000; 60:1647-54. [PMID: 11077047 DOI: 10.1016/s0006-2952(00)00474-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To examine the importance of the nine native cysteine residues in the human A(1) adenosine receptor, each cysteine was individually mutated to both serine and alanine. Saturation binding with the A(1) selective antagonist [(3)H]DPCPX [8-cyclopentyl-1,3-di(2, 3-(3)H-propyl)xanthine] resulted in a wild-type K(d) value of 0.92 nM. All serine and alanine mutants had similar K(d) values with the exception of serine/alanine mutations at Cys80 and Cys169. These two cysteine residues, which are highly conserved in G protein-coupled receptors and hypothesized to be linked through a disulfide bridge, demonstrated no detectable binding with [(3)H]DPCPX. Both serine and alanine mutations at residues Cys80 and Cys169 resulted in receptors that were not detectable at the cell surface, as visualized by immunostaining. The serine/alanine mutants that did bind [(3)H]DPCPX were characterized further through competition binding with the antagonist theophylline and the agonists NECA (5'-N-ethylcarboxamidoadenosine) and R-PIA [(R)N(6)-phenylisopropyl adenosine]. The wild-type theophylline K(i) value was 2.41 microM, with the serine/alanine mutants having similar values. Wild-type NECA and R-PIA K(i) values were 0.74 microM and 97.0 nM, respectively. All mutants had K(i) values similar to wild-type with the exception of the Cys85Ser mutant, which had NECA and R-PIA values of 9.30 microM and 387.3 nM, respectively. These data show that Cys80 and Cys169 are absolutely required for delivery of the receptor to the plasma membrane. The Cys85Ser data indicate that although a cysteine is not required at this position, this residue may have an important role in ligand binding or for the structure of the receptor.
Collapse
Affiliation(s)
- D J Scholl
- Department of Pharmacology, Vanderbilt University School of Medicine, 37232-6600, USA, Nashville, TN, USA
| | | |
Collapse
|
34
|
Kim YC, Ji XD, Melman N, Linden J, Jacobson KA. Anilide derivatives of an 8-phenylxanthine carboxylic congener are highly potent and selective antagonists at human A(2B) adenosine receptors. J Med Chem 2000; 43:1165-72. [PMID: 10737749 PMCID: PMC9364909 DOI: 10.1021/jm990421v] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
No highly selective antagonists of the A(2B) adenosine receptor (AR) have been reported; however such antagonists have therapeutic potential as antiasthmatic agents. Here we report the synthesis of potent and selective A(2B) receptor antagonists. The structure-activity relationships (SAR) of 8-phenyl-1, 3-di-(n-propyl)xanthine derivatives in binding to recombinant human A(2B) ARs in HEK-293 cells (HEK-A(2B)) and at other AR subtypes were explored. Various amide derivatives of 8-[4-[[carboxymethyl]oxy]phenyl]-1,3-di-(n-propyl)xanthine, 4a, were synthesized. A comparison of aryl, alkyl, and aralkyl amides demonstrated that simple anilides, particularly those substituted in the para-position with electron-withdrawing groups, such as nitro, cyano, and acetyl, bind selectively to human A(2B) receptors in the range of 1-3 nM. The unsubstituted anilide 12 had a K(i) value at A(2B) receptors of 1.48 nM but was only moderately selective versus human A(1)/A(2A) receptors and nonselective versus rat A(1) receptors. Highly potent and selective A(2B) antagonists were a p-aminoacetophenone derivative 20 (K(i) value 1.39 nM) and ap-cyanoanilide 27 (K(i) value 1.97 nM). Compound 27 was 400-, 245-, and 123-fold selective for human A(2B) receptors versus human A(1)/A(2A)/A(3) receptors, respectively, and 8.5- and 310-fold selective versus rat A(1)/A(2A) receptors, respectively. Substitution of the 1,3-dipropyl groups with 1,3-diethyl offered no disadvantage for selectivity, and high affinities at A(2B) receptors were maintained. Substitution of the p-carboxymethyloxy group of 4a and its amides with acrylic acid decreased affinity at A(2B) receptors while increasing affinity at A(1) receptors. 1, 3-Di(cyclohexylmethyl) groups greatly reduced affinity at ARs, although the p-carboxymethyloxy derivative 9 was moderately selective for A(2B) receptors. Several selective A(2B) antagonists inhibited NECA-stimulated calcium mobilization in HEK-A(2B) cells.
Collapse
Affiliation(s)
- Yong-Chul Kim
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Xiao-duo Ji
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Neli Melman
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Joel Linden
- Department of Internal Medicine and Molecular Physiology & Biological Physics, University of Virginia, Box MR4 6012, Health Science Center, Charlottesville, Virginia 22908
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
- Correspondence to: Dr. K. A. Jacobson, Bldg. 8A, Rm. B1A-19, NIH, NIDDK, LBC, Bethesda, MD 20892-0810. Tel: (301) 496-9024. Fax: (301) 480-8422.
| |
Collapse
|
35
|
Abstract
Heparin cofactor II (HCII) is a serpin whose thrombin inhibition activity is accelerated by glycosaminoglycans. We describe the novel properties of a carboxyl-terminal histidine-tagged recombinant HCII (rHCII-CHis(6)). Thrombin inhibition by rHCII-CHis(6) was increased >2-fold at approximately 5 microgram/ml heparin compared with wild-type recombinant HCII (wt-rHCII) at 50-100 microgram/ml heparin. Enhanced activity of rHCII-CHis(6) was reversed by treatment with carboxypeptidase A. We assessed the role of the HCII acidic domain by constructing amino-terminal deletion mutants (Delta1-52, Delta1-68, and Delta1-75) in wt-rHCII and rHCII-CHis(6). Without glycosaminoglycan, unlike wt-rHCII deletion mutants, the rHCII-CHis(6) deletion mutants were less active compared with full-length rHCII-CHis(6). With glycosaminoglycans, Delta1-68 and Delta1-75 rHCIIs were all less active. We assessed the character of the tag by comparing rHCII-CHis(6), rHCII-CAla(6), and rHCII-CLys(6) to wt-rHCII. Only rHCII-CHis(6) had increased activity with heparin, whereas all three mutants have increased heparin binding. We generated a carboxyl-terminal histidine-tagged recombinant antithrombin III to study the tag on another serpin. Interestingly, this mutant antithrombin III had reduced heparin cofactor activity compared with wild-type protein. In a plasma-based assay, the glycosaminoglycan-dependent inhibition of thrombin by rHCII-CHis(6) was significantly greater compared with wt-rHCII. Thus, HCII variants with increased function, such as rHCII-CHis(6), may offer novel reagents for clinical application.
Collapse
Affiliation(s)
- S J Bauman
- Department of Pathology, Center for Thrombosis and Hemostasis, The University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7035, USA
| | | |
Collapse
|
36
|
Okusa MD, Linden J, Macdonald T, Huang L. Selective A2A adenosine receptor activation reduces ischemia-reperfusion injury in rat kidney. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:F404-12. [PMID: 10484524 DOI: 10.1152/ajprenal.1999.277.3.f404] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A2A adenosine receptors (A2A-ARs) are known modulators of renal hemodynamics and potent inhibitors of inflammation. We sought to determine whether selective activation of A2A-ARs protects kidneys from ischemia-reperfusion injury. The ester derivative of DWH-146 (DWH-146e), a selective A2A agonist, was found to be more potent and selective for A2A-ARs than the prototype compound CGS-21680. Osmotic minipumps were implanted subcutaneously to infuse into rats either vehicle or DWH-146e (0.004 microg. kg(-1). min(-1)), during and after ischemia-reperfusion injury. Following 24 and 48 h of reperfusion, the rise in serum creatinine and blood urea nitrogen for vehicle-treated rats was substantially elevated compared with DWH-146e-treated rats. Histological examination revealed widespread tubular epithelial necrosis and vascular congestion in the outer medulla of vehicle-treated compared with DWH-146e-treated animals. ZM-241385, a selective A(2A) antagonist, blocked the protective effect of DWH-146e. Delaying administration of DWH-146e until the initiation of reperfusion also decreased serum creatinine. We conclude that 1) selective A2A-AR activation by DWH-146e reduces ischemia-reperfusion injury in rat kidneys, 2) the effect of DWH-146e is A2A receptor mediated, and 3) the protective effects are mediated by preventing injury during the reperfusion period.
Collapse
Affiliation(s)
- M D Okusa
- Department of Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
| | | | | | | |
Collapse
|
37
|
Kim YC, Karton Y, Ji XD, Melman N, Linden J, Jacobson KA. Acyl-hydrazide derivatives of a xanthine carboxylic congener (XCC) as selective antagonists at human A2B adenosine receptors. Drug Dev Res 1999; 47:178-188. [DOI: 10.1002/(sici)1098-2299(199908)47:4<178::aid-ddr4>3.0.co;2-l] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
38
|
Hoffmann C, Moro S, Nicholas RA, Harden TK, Jacobson KA. The role of amino acids in extracellular loops of the human P2Y1 receptor in surface expression and activation processes. J Biol Chem 1999; 274:14639-47. [PMID: 10329657 PMCID: PMC3449168 DOI: 10.1074/jbc.274.21.14639] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The P2Y1 receptor is a membrane-bound G protein-coupled receptor stimulated by adenine nucleotides. Using alanine scanning mutagenesis, the role in receptor activation of charged amino acids (Asp, Glu, Lys, and Arg) and cysteines in the extracellular loops (EL) of the human P2Y1 receptor has been investigated. The mutant receptors were expressed in COS-7 cells and measured for stimulation of phospholipase C induced by the potent agonist 2-methylthioadenosine-5'-diphosphate (2-MeSADP). In addition to single point mutations, all receptors carried the hemagglutinin epitope at the N- terminus for detection of cell-surface expression. The C124A and C202A mutations, located near the exofacial end of transmembrane helix 3 and in EL2, respectively, ablated phospholipase C stimulation by =100 microM 2-MeSADP. Surface enzyme-linked immunosorbent assay detection of both mutant receptors showed <10% expression, suggesting that a critical disulfide bridge between EL2 and the upper part of transmembrane 3, as found in many other G protein-coupled receptors, is required for proper trafficking of the P2Y1 receptor to the cell surface. In contrast, the C42A and C296A mutant receptors (located in the N-terminal domain and EL3) were activated by 2-MeSADP, but the EC50 values were >1000-fold greater than for the wild-type receptor. The double mutant receptor C42A/C296A exhibited no additive shift in the concentration-response curve for 2-MeSADP. These data suggest that Cys42 and Cys296 form another disulfide bridge in the extracellular region, which is critical for activation. Replacement of charged amino acids produced only minor changes in receptor activation, with two remarkable exceptions. The E209A mutant receptor (EL2) exhibited a >1000-fold shift in EC50. However, if Glu209 were substituted with amino acids capable of hydrogen bonding (Asp, Gln, or Arg), the mutant receptors responded like the wild-type receptor. Arg287 in EL3 was impaired similarly to Glu209 when substituted by alanine. Substitution of Arg287 by lysine, another positively charged residue, failed to fully restore wild-type activity.
Collapse
Affiliation(s)
- Carsten Hoffmann
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Stefano Moro
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Robert A. Nicholas
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - T. Kendall Harden
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
39
|
Jacobson KA, IJzerman AP, Linden J. 1,3-Dialkylxanthine Derivatives Having High Potency as Antagonists at Human A 2B Adenosine Receptors. Drug Dev Res 1999; 47:45-53. [PMID: 38239816 PMCID: PMC10795772 DOI: 10.1002/(sici)1098-2299(199905)47:1<45::aid-ddr6>3.0.co;2-u] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The structure-activity relationships (SAR) of alkylxanthine derivatives as antagonists at the recombinant human adenosine receptors were explored in order to identify selective antagonists of A2B receptors. The effects of lengthening alkyl substituents from methyl to butyl at 1- and 3-positions and additional substitution at the 7- and 8-positions were probed. Ki values, determined in competition binding in membranes of HEK-293 cells expressing A2B receptors using 125I-ABOPX (125I-3-(4-amino-3-iodobenzyl)-8-(phenyl-4-oxyacetate)-1-propylxanthine), were approximately 10 to 100 nM for 8-phenylxanthine functionalized congeners. Xanthines containing 8-aryl, 8-alkyl, and 8-cycloalkyl substituents, derivatives of XCC (8-[4-[[[carboxy]methyl]oxy]phenyl]-1,3-dipropylxanthine) and XAC (8-[4-[[[[(2-aminoethyl)amino]carbonyl]methyl]-oxy]phenyl]-1,3-dipropylxanthine), containing various ester and amide groups, including L- and D-amino acid conjugates, were included. Enprofylline was 2-fold more potent than theophylline in A2B receptor binding, and the 2-thio modification was not tolerated. Among the most potent derivatives examined were XCC, its hydrazide and aminoethyl and fluoroethyl amide derivatives, XAC, N-hydroxyethyl-XAC, and the L-citrulline and D-p-aminophenylalanine conjugates of XAC. An N-hydroxysuccinimide ester of XCC (XCC-NHS, MRS 1204) bound to A2B receptors with a Ki of 9.75 nM and was the most selective (at least 20-fold) in this series. In a functional assay of recombinant human A2B receptors, four of these potent xanthines were shown to fully antagonize the effects of NECA-induced stimulation of cyclic AMP accumulation.
Collapse
Affiliation(s)
- Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Ad P. IJzerman
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Leiden, The Netherlands
| | - Joel Linden
- Department of Internal Medicine and Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| |
Collapse
|
40
|
Abstract
Epitope tagging is a recombinant DNA method by which a protein encoded by a cloned gene is made immunoreactive to a known antibody. This review discusses the major advantages and limitations of epitope tagging and describes a number of recent applications. Major areas of application include monitoring protein expression, localizing proteins at the cellular and subcellular levels, and protein purification, as well as the analysis of protein topology, dynamics and interactions. Recently the method has also found use in transgenic and gene therapy studies and in the emerging fields of functional genomics and proteomics.
Collapse
Affiliation(s)
- J W Jarvik
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
| | | |
Collapse
|
41
|
Rosin DL, Robeva A, Woodard RL, Guyenet PG, Linden J. Immunohistochemical localization of adenosine A2A receptors in the rat central nervous system. J Comp Neurol 1998. [DOI: 10.1002/(sici)1096-9861(19981116)401:2<163::aid-cne2>3.0.co;2-d] [Citation(s) in RCA: 284] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|
42
|
Wenzel-Seifert K, Hurt CM, Seifert R. High constitutive activity of the human formyl peptide receptor. J Biol Chem 1998; 273:24181-9. [PMID: 9727041 DOI: 10.1074/jbc.273.37.24181] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The formyl peptide receptor (FPR) couples to pertussis toxin (PTX)-sensitive Gi-proteins to activate chemotaxis and exocytosis in neutrophils. PTX reduces not only formyl peptide-stimulated but also agonist-independent ("basal") Gi-protein activity, suggesting that the FPR is constitutively active. We aimed at identifying an inverse FPR agonist, i.e. a compound that suppresses constitutive FPR activity. In Sf9 insect cell membranes, the G-protein heterotrimer Gialpha2beta1gamma2 reconstituted N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-stimulated guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) binding and GTPgammaS-sensitive high affinity [3H]FMLP binding. The FPR "antagonist" cyclosporin H (CsH) potently and efficiently reduced basal GTPgammaS binding in Sf9 membranes. Another FPR antagonist, N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L-leucyl-L- phenylalanine did not inhibit basal GTPgammaS binding but blocked the inhibitory effect of CsH on GTPgammaS binding. Na+ reduced basal GTPgammaS binding and eliminated the inhibitory effect of CsH. Similar effects of FMLP, CsH, and Na+ as in Sf9 membranes were observed with FPR expressed in the mammalian cell line HEK293. Our data show that the human FPR possesses high constitutive activity. CsH is an inverse FPR agonist and stabilizes the FPR in an inactive state. Na+ also stabilizes the FPR in an inactive state and, thereby, diminishes inverse agonist efficacy.
Collapse
MESH Headings
- Animals
- Cell Line
- Cell Membrane/physiology
- Cyclosporine/pharmacology
- GTP-Binding Protein alpha Subunits, Gi-Go/isolation & purification
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Proteins/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
- Humans
- Kinetics
- Models, Chemical
- N-Formylmethionine Leucyl-Phenylalanine/metabolism
- N-Formylmethionine Leucyl-Phenylalanine/pharmacology
- Receptors, Formyl Peptide
- Receptors, Immunologic/agonists
- Receptors, Immunologic/antagonists & inhibitors
- Receptors, Immunologic/metabolism
- Receptors, Peptide/agonists
- Receptors, Peptide/antagonists & inhibitors
- Receptors, Peptide/metabolism
- Recombinant Proteins/metabolism
- Sodium/pharmacology
- Spodoptera
- Transfection
Collapse
Affiliation(s)
- K Wenzel-Seifert
- Howard Hughes Medical Institute, Stanford University Medical School, Stanford, California 94305-5428, USA
| | | | | |
Collapse
|
43
|
Pawate S, Schey KL, Meier GP, Ullian ME, Mais DE, Halushka PV. Expression, characterization, and purification of C-terminally hexahistidine-tagged thromboxane A2 receptors. J Biol Chem 1998; 273:22753-60. [PMID: 9712907 DOI: 10.1074/jbc.273.35.22753] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thromboxane A2 (TxA2) receptors belong to the class of G-protein-coupled receptors. Knowledge of the relationship of structure to function for TxA2 receptors is limited because of their low levels of expression, lengthy purification procedures and poor recoveries. A C-terminal hexahistidine-tag (C-His) was ligated to the alpha-isoform of TxA2 receptors and expressed in COS-7 and Chinese hamster ovary cells. The C-His-TxA2 receptors bound the radioligands 125I-7-[(1R,2S,3S,5R)-6, 6-dimethyl-3-(4-benzenesulfonylamino)bicyclo[3.1. 1]hept-2-yl]-5(Z)-heptenoic acid, an antagonist, and 125I-[1S-1alpha, 2beta(5Z),3alpha(1E,3S*), 4alpha]-7-[3[(3-hydroxy-4-(4'-phenoxy)-1butenyl)-7-oxabicycl o-[2.2. 1]heptan-2-yl]-5-heptanoic acid, an agonist, with affinities not significantly different from those of the wild type (wt)-TxA2 receptors. LipofectAMINE transfection of the cDNAs resulted in high levels of expression (Bmax = 95 +/- 6 pmol/mg) of the C-His-TxA2 receptors. In competition binding studies the IC50 values of five different ligands were not significantly different between C-His-TxA2 and wt-TxA2 receptors. Agonist-induced stimulation of cAMP and total inositol phosphate formation were not significantly different between the two receptors. Purification on a Ni2+-NTA column resulted in a rapid (within 4 h) purification with a 36 +/- 2% recovery and a 30 +/- 6-fold purification (n = 5). The partially purified receptors were resolved on SDS-polyacrylamide gel electrophoresis, transferred to a nitrocellulose membrane, dissolved in acetone/trifluoroacetic acid/hexafluoroisopropanol/sinapinic acid, and successfully subjected to matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis. The results suggest that the combination of a high level of expression of C-His-TxA2 receptors and a rapid purification procedure followed by SDS- polyacrylamide gel electrophoresis may provide a useful approach for mass-spectrometry based structure-function and other studies of TxA2 receptors.
Collapse
MESH Headings
- Affinity Labels
- Animals
- Binding, Competitive
- Blotting, Western
- CHO Cells
- COS Cells
- Cricetinae
- Cyclic AMP/biosynthesis
- DNA, Complementary
- Electrophoresis, Polyacrylamide Gel
- Histidine/metabolism
- Inositol 1,4,5-Trisphosphate/biosynthesis
- Radioligand Assay
- Receptors, Thromboxane/genetics
- Receptors, Thromboxane/isolation & purification
- Receptors, Thromboxane/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/isolation & purification
- Recombinant Fusion Proteins/metabolism
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Collapse
Affiliation(s)
- S Pawate
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | | | | | | | | | | |
Collapse
|
44
|
Yasuda H, Lindorfer MA, Myung CS, Garrison JC. Phosphorylation of the G protein gamma12 subunit regulates effector specificity. J Biol Chem 1998; 273:21958-65. [PMID: 9705336 DOI: 10.1074/jbc.273.34.21958] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the G protein betagamma dimer is an important mediator in cell signaling, the mechanisms regulating its activity have not been widely investigated. The gamma12 subunit is a known substrate for protein kinase C, suggesting phosphorylation as a potential regulatory mechanism. Therefore, recombinant beta1 gamma12 dimers were overexpressed using the baculovirus/Sf9 insect cell system, purified, and phosphorylated stoichiometrically with protein kinase C alpha. Their ability to support coupling of the Gi1 alpha subunit to the A1 adenosine receptor and to activate type II adenylyl cyclase or phospholipase C-beta was examined. Phosphorylation of the beta1 gamma12 dimer increased its potency in the receptor coupling assay from 6.4 to 1 nM, changed the Kact for stimulation of type II adenylyl cyclase from 14 to 37 nM, and decreased its maximal efficacy by 50%. In contrast, phosphorylation of the dimer had no effect on its ability to activate phospholipase C-beta. The native beta1gamma10 dimer, which has 4 similar amino acids in the phosphorylation site at the N terminus, was not phosphorylated by protein kinase C alpha. Creation of a phosphorylation site in the N terminus of the protein (Gly4 --> Lys) resulted in a beta1 gamma10G4K dimer which could be phosphorylated. The activities of this beta gamma dimer were similar to those of the phosphorylated beta1 gamma12 dimer. Thus, phosphorylation of the beta1 gamma12 dimer on the gamma subunit with protein kinase C alpha regulates its activity in an effector-specific fashion. Because the gamma12 subunit is widely expressed, phosphorylation may be an important mechanism for integration of the multiple signals generated by receptor activation.
Collapse
Affiliation(s)
- H Yasuda
- Department of Pharmacology, Health Sciences Center, University of Virginia, Charlottesville, Virginia 22908, USA
| | | | | | | |
Collapse
|
45
|
Linden J, Auchampach JA, Jin X, Figler RA. The structure and function of A1 and A2B adenosine receptors. Life Sci 1998; 62:1519-24. [PMID: 9585129 DOI: 10.1016/s0024-3205(98)00100-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Of the four G protein coupled adenosine receptor (AR) subtypes, the A1 is best suited for studies of reconstitution with G proteins. Recombinant A1 receptors extended with hexahistidine and FLAG have been purified to near homogeneity. In reconstitution assays using pure recombinant G protein subunits, the composition of the gamma subunit influences coupling to purified A1ARs. The least well characterized AR is the A2B. New data indicate that A(2B)ARs can trigger the degranulation of canine and human mast cell lines. Recombinant human A(2B)ARs are blocked by the anti-asthma drugs theophylline and enprofylline at concentrations that are used therapeutically to treat asthma. Although A(2B)ARs have long been known to stimulate adenylyl cyclase, they also can activate phospholipase C and mobilize Ca2+ by signaling through Gq/11. There is great potential for new therapies based on compounds that selectively target individual AR subtypes.
Collapse
Affiliation(s)
- J Linden
- University of Virginia, Health Sciences Center, Charlottesville 22908, USA
| | | | | | | |
Collapse
|
46
|
Moro S, Guo D, Camaioni E, Boyer JL, Harden TK, Jacobson KA. Human P2Y1 receptor: molecular modeling and site-directed mutagenesis as tools to identify agonist and antagonist recognition sites. J Med Chem 1998; 41:1456-66. [PMID: 9554879 PMCID: PMC3469197 DOI: 10.1021/jm970684u] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The molecular basis for recognition by human P2Y1 receptors of the novel, competitive antagonist 2'-deoxy-N6-methyladenosine 3', 5'-bisphosphate (MRS 2179) was probed using site-directed mutagenesis and molecular modeling. The potency of this antagonist was measured in mutant receptors in which key residues in the transmembrane helical domains (TMs) 3, 5, 6, and 7 were replaced by Ala or other amino acids. The capacity of MRS 2179 to block stimulation of phospholipase C promoted by 2-methylthioadenosine 5'-diphosphate (2-MeSADP) was lost in P2Y1 receptors having F226A, K280A, or Q307A mutations, indicating that these residues are critical for the binding of the antagonist molecule. Mutation of the residues His132, Thr222, and Tyr136 had an intermediate effect on the capacity of MRS 2179 to block the P2Y1 receptor. These positions therefore appear to have a modulatory role in recognition of this antagonist. F131A, H277A, T221A, R310K, or S317A mutant receptors exhibited an apparent affinity for MRS 2179 that was similar to that observed with the wild-type receptor. Thus, Phe131, Thr221, His277, and Ser317 are not essential for antagonist recognition. A computer-generated model of the human P2Y1 receptor was built and analyzed to help interpret these results. The model was derived through primary sequence comparison, secondary structure prediction, and three-dimensional homology building, using rhodopsin as a template, and was consistent with data obtained from mutagenesis studies. We have introduced a "cross-docking" procedure to obtain energetically refined 3D structures of the ligand-receptor complexes. Cross-docking simulates the reorganization of the native receptor structure induced by a ligand. A putative nucleotide binding site was localized and used to predict which residues are likely to be in proximity to agonists and antagonists. According to our model TM6 and TM7 are close to the adenine ring, TM3 and TM6 are close to the ribose moiety, and TM3, TM6, and TM7 are near the triphosphate chain.
Collapse
Affiliation(s)
- Stefano Moro
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Danping Guo
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Emidio Camaioni
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - José L. Boyer
- Department of Pharmacology, University of North Carolina, School of Medicine, Chapel Hill, North Carolina 27599-7365
| | - T. Kendall Harden
- Department of Pharmacology, University of North Carolina, School of Medicine, Chapel Hill, North Carolina 27599-7365
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| |
Collapse
|
47
|
Fletcher JE, Lindorfer MA, DeFilippo JM, Yasuda H, Guilmard M, Garrison JC. The G protein beta5 subunit interacts selectively with the Gq alpha subunit. J Biol Chem 1998; 273:636-44. [PMID: 9417126 DOI: 10.1074/jbc.273.1.636] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The diversity in the heterotrimeric G protein alpha, beta, and gamma subunits may allow selective protein-protein interactions and provide specificity for signaling pathways. We examined the ability of five alpha subunits (alphai1, alphai2, alphao, alphas, and alphaq) to associate with three beta subunits (beta1, beta2, and beta5) dimerized to a gamma2 subunit containing an amino-terminal hexahistidine-FLAG affinity tag (gamma2HF). Sf9 insect cells were used to overexpress the recombinant proteins. The hexahistidine-FLAG sequence does not hinder the function of the beta1gamma2HF dimer as it can be specifically eluted from an alphai1-agarose column with GDP and AlF4-, and purified beta1gamma2HF dimer stimulates type II adenylyl cyclase. The beta1gamma2HF and beta2gamma2HF dimers immobilized on an anti-FLAG affinity column bound all five alpha subunits tested, whereas the beta5gamma2HF dimer bound only alphaq. The ability of other alpha subunits to compete with the alphaq subunit for binding to the beta5gamma2HF dimer was tested. Addition of increasing amounts of purified, recombinant alphai1 to the alphaq in a Sf9 cell extract did not decrease the amount of alphaq bound to the beta5gamma2HF column. When G proteins in an extract of brain membranes were activated with GDP and AlF4- and deactivated in the presence of equal amounts of the beta1gamma2HF or beta5gamma2HF dimers, only alphaq bound to the beta5gamma2HF dimer. The alphaq-beta5gamma2HF interaction on the column was functional as GDP, and AlF4- specifically eluted alphaq from the column. These results indicate that although the beta1 and beta2 subunits interact with alpha subunits from the alphai, alphas, and alphaq families, the structurally divergent beta5 subunit only interacts with alphaq.
Collapse
Affiliation(s)
- J E Fletcher
- Department of Pharmacology, Health Sciences Center, University of Virginia, Charlottesville, Virginia 22908, USA
| | | | | | | | | | | |
Collapse
|
48
|
Okusa MD, Huang L, Momose-Hotokezaka A, Huynh LP, Mangrum AJ. Regulation of adenylyl cyclase in polarized renal epithelial cells by G protein-coupled receptors. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:F883-91. [PMID: 9435676 DOI: 10.1152/ajprenal.1997.273.6.f883] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We employed two guanine nucleotide binding protein (G protein)-coupled receptors known to be targeted to opposite domains in renal epithelial cells to test the hypothesis that the polarized receptor expression of receptors regulates the activity of the receptor's effector molecule, adenylyl cyclase. We used LLC-PK1 cells stably transfected with cDNA encoding the alpha 2B-adrenergic receptor (alpha 2B-AR) or A1-adenosine receptor (A1-AdR). Immunohistochemistry and Western blot analysis confirmed the basolateral and apical expression of alpha 2B-ARs and A1-AdRs, respectively. Adenylyl cyclase activity was assessed by measuring cAMP accumulation following the addition of forskolin (10 microM) in the presence of 3-isobutyl-1-methylxanthine to apical or basolateral chambers of confluent monolayers. A five- to sixfold increase in cAMP accumulation occurred following apical (or basolateral) stimulation of LLC-PK1 cells expressing apical (or basolateral) receptors in comparison to forskolin stimulation of corresponding domains of untransfected cells. We conclude 1) adenylyl cyclase activity is present at or near the apical and basolateral domains of LLC-PK1 cells, and 2) factors that regulate the polarized expression of inhibitory G protein-coupled receptors may also regulate local adenylyl cyclase activity.
Collapse
Affiliation(s)
- M D Okusa
- Department of Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA
| | | | | | | | | |
Collapse
|
49
|
Woodring PJ, Garrison JC. Expression, purification, and regulation of two isoforms of the inositol 1,4,5-trisphosphate 3-kinase. J Biol Chem 1997; 272:30447-54. [PMID: 9374536 DOI: 10.1074/jbc.272.48.30447] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The level of inositol 1,4,5-trisphosphate in the cytoplasm is tightly regulated by two enzymes, the inositol 1,4,5,5-phosphatase and the inositol 1,4,5-trisphosphate 3-kinase. Two isoforms of the inositol 1,4,5-trisphosphate 3-kinase have been identified, the A form and the B form. The regulatory properties of the two isoforms were compared following overexpression and purification of the proteins from a v-src transformed mammalian cell line. The highly purified, recombinant inositol 1,4,5-trisphosphate 3-kinases were differentially regulated by calcium/calmodulin and via phosphorylation by protein kinase C or the cyclic AMP-dependent protein kinase. Both enzymes had similar affinities for inositol 1,4, 5-trisphosphate (Km 2-5 mu M). Calcium/calmodulin stimulated the activity of isoform A about 2.5-fold, whereas the activity of isoform B was increased 20-fold. The cyclic AMP-dependent protein kinase phosphorylated the inositol 1,4,5-trisphosphate 3-kinase A to the extent of 0.9 mol/mol and isoform B to 1 mol/mol. Protein kinase C phosphorylated isoform A to the extent of 2 mol/mol and isoform B to 2.7 mol/mol. Phosphorylation of isoform A by the cyclic AMP-dependent protein kinase caused a 2.5-fold increase in its activity when assayed in the absence of calcium/calmodulin, whereas phosphorylation by protein kinase C decreased activity by 72%. The activity of isoform B in the absence of calcium/calmodulin was not affected by phosphorylation using either kinase. When assayed in the presence of calcium/calmodulin, phosphorylation of isoform A by the cyclic AMP-dependent protein kinase increased activity 1.5-fold, whereas phosphorylation of isoform B decreased activity by 45%. Phosphorylation of either isoform A or B by protein kinase C resulted in a 70% reduction of calcium/calmodulin-stimulated activity. Differential expression and regulation of the two inositol 1,4,5-trisphosphate 3-kinase isoforms provides multiple mechanisms for regulating the cytosolic level of inositol 1,4,5-trisphosphate in cells.
Collapse
Affiliation(s)
- P J Woodring
- Department of Pharmacology and Cancer Research Center, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
| | | |
Collapse
|
50
|
Beukers MW, Klaassen CH, De Grip WJ, Verzijl D, Timmerman H, Leurs R. Heterologous expression of rat epitope-tagged histamine H2 receptors in insect Sf9 cells. Br J Pharmacol 1997; 122:867-74. [PMID: 9384502 PMCID: PMC1565019 DOI: 10.1038/sj.bjp.0701466] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. Rat histamine H2 receptors were epitope-tagged with six histidine residues at the C-terminus to allow immunological detection of the receptor. Recombinant baculoviruses containing the epitope-tagged H2 receptor were prepared and were used to infect insect Sf9 cells. 2. The His-tagged H2 receptors expressed in insect Sf9 cells showed typical H2 receptor characteristics as determined with [125I]-aminopotentidine (APT) binding studies. 3. In Sf9 cells expressing the His-tagged H2 receptor histamine was able to stimulate cyclic AMP production 9 fold (EC50=2.1+/-0.1 microM) by use of the endogenous signalling pathway. The classical antagonists cimetidine, ranitidine and tiotidine inhibited histamine induced cyclic AMP production with Ki values of 0.60+/-0.43 microM, 0.25+/-0.15 microM and 28+/-7 nM, respectively (mean+/-s.e.mean, n=3). 4. The expression of the His-tagged H2 receptors in infected Sf9 cells reached functional levels of 6.6+/-0.6 pmol mg(-1) protein (mean+/-s.e.mean, n=3) after 3 days of infection. This represents about 2 x 10(6) copies of receptor/cell. Preincubation of the cells with 0.03 mM cholesterol-beta-cyclodextrin complex resulted in an increase of [125I]-APT binding up to 169+/-5% (mean+/-s.e.mean, n=3). 5. The addition of 0.03 mM cholesterol-beta-cyclodextrin complex did not affect histamine-induced cyclic AMP production. The EC50 value of histamine was 3.1+/-1.7 microM in the absence of cholesterol-beta-cyclodextrin complex and 11.1+/-5.5 microM in the presence of cholesterol-beta-cyclodextrin complex (mean+/-s.e.mean, n=3). Also, the amount of cyclic AMP produced in the presence of 100 microM histamine was identical, 85+/-18 pmol/10(6) cells in the absence and 81+/-11 pmol/10(6) cells in the presence of 0.03 mM cholesterol-beta-cyclodextrin complex (mean+/-s.e.mean, n=3). 6. Immunofluorescence studies with an antibody against the His-tag revealed that the majority of the His-tagged H2 receptors was localized inside the insect Sf9 cells, although plasma membrane labelling could be identified as well. 7. These experiments demonstrate the successful expression of His-tagged histamine H2 receptors in insect Sf9 cells. The H2 receptors couple functionally to the insect cell adenylate cyclase. However, our studies with cholesterol complementation and with immunofluorescent detection of the His-tag reveal that only a limited amount of H2 receptor protein is functional. These functional receptors are targeted to the plasma membrane.
Collapse
Affiliation(s)
- M W Beukers
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Amsterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|