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Glenn NAK, Finlay DB, Carruthers ER, Mountjoy KG, Walker CS, Grimsey NL. RAMP and MRAP accessory proteins have selective effects on expression and signalling of the CB 1, CB 2, GPR18 and GPR55 cannabinoid receptors. Br J Pharmacol 2024; 181:2212-2231. [PMID: 37085333 DOI: 10.1111/bph.16095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/10/2023] [Accepted: 04/14/2023] [Indexed: 04/23/2023] Open
Abstract
BACKGROUND AND PURPOSE Receptor activity-modifying proteins (RAMPs) and melanocortin receptor accessory proteins (MRAPs) modulate expression and signalling of calcitonin and melanocortin GPCRs. Interactions with other GPCRs have also been reported. The cannabinoid receptors, CB1 and CB2, and two putative cannabinoid receptors, GPR18 and GPR55, exhibit substantial intracellular expression and there are discrepancies in ligand responsiveness between studies. We investigated whether interactions with RAMPs or MRAPs could explain these phenomena. EXPERIMENTAL APPROACH Receptors and accessory proteins were co-expressed in HEK-293 cells. Selected receptors were studied at basal expression levels and also with enhanced expression produced by incorporation of a preprolactin signal sequence/peptide (pplss). Cell surface and total expression of receptors and accessory proteins were quantified using immunocytochemistry. Signalling was measured using cAMP (CAMYEL) and G protein dissociation (TRUPATH Gα13) biosensors. KEY RESULTS MRAP2 enhanced surface and total expression of GPR18. Pplss-GPR18 increased detection of cell surface MRAP2. MRAP1α and MRAP2 reduced GPR55 surface and total expression, correlating with reduced constitutive, but not agonist-induced, signalling. GPR55, pplss-CB1 and CB2 reduced detection of MRAP1α at the cell surface. Pplss-CB1 agonist potency was reduced by MRAP2 in Gα13 but not cAMP assays, consistent with MRAP2 reducing pplss-CB1 expression. Some cannabinoid receptors increased RAMP2 or RAMP3 total expression without influencing surface expression. CONCLUSIONS AND IMPLICATIONS Mutual influences on expression and/or function for specific accessory protein-receptor pairings raises the strong potential for physiological and disease-relevant consequences. Sequestration and/or hetero-oligomerisation of cannabinoid receptors with accessory proteins is a possible novel mechanism for receptor crosstalk. LINKED ARTICLES This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
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MESH Headings
- Humans
- HEK293 Cells
- Receptors, G-Protein-Coupled/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, Cannabinoid/metabolism
- Signal Transduction
- Receptor, Cannabinoid, CB1/metabolism
- Receptor Activity-Modifying Proteins/metabolism
- Receptor, Cannabinoid, CB2/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/genetics
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Affiliation(s)
- Nathaniel A K Glenn
- Department of Pharmacology and Clinical Pharmacology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - David B Finlay
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Emma R Carruthers
- Department of Pharmacology and Clinical Pharmacology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Kathleen G Mountjoy
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Molecular Medicine and Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Christopher S Walker
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
- School of Biological Sciences, Faculty of Science, University of Auckland, Auckland, New Zealand
| | - Natasha L Grimsey
- Department of Pharmacology and Clinical Pharmacology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
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Sehgal ANA, Safran J, Kratzer B, Gattinger P, Stieger RB, Musiejovsky L, Trapin D, Ettel P, Körmöczi U, Rottal A, Borochova K, Dorofeeva Y, Tulaeva I, Weber M, Grabmeier-Pfistershammer K, Perkmann T, Wiedermann U, Valenta R, Pickl WF. Flow Cytometry-Based Measurement of Antibodies Specific for Cell Surface-Expressed Folded SARS-CoV-2 Receptor-Binding Domains. Vaccines (Basel) 2024; 12:377. [PMID: 38675759 PMCID: PMC11053794 DOI: 10.3390/vaccines12040377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 03/20/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has now become endemic and is currently one of the important respiratory virus infections regularly affecting mankind. The assessment of immunity against SARS-CoV-2 and its variants is important for guiding active and passive immunization and SARS-CoV-2-specific treatment strategies. METHODS We here devised a novel flow cytometry-based diagnostic platform for the assessment of immunity against cell-bound virus antigens. This platform is based on a collection of HEK-293T cell lines which, as exemplified in our study, stably express the receptor-binding domains (RBDs) of the SARS-CoV-2 S-proteins of eight major SARS-CoV-2 variants, ranging from Wuhan-Hu-1 to Omicron. RESULTS RBD-expressing cell lines stably display comparable levels of RBD on the surface of HEK-293T cells, as shown with anti-FLAG-tag antibodies directed against a N-terminally introduced 3x-FLAG sequence while the functionality of RBD was proven by ACE2 binding. We exemplify the usefulness and specificity of the cell-based test by direct binding of IgG and IgA antibodies of SARS-CoV-2-exposed and/or vaccinated individuals in which the assay shows a wide linear performance range both at very low and very high serum antibody concentrations. In another application, i.e., antibody adsorption studies, the test proved to be a powerful tool for measuring the ratios of individual variant-specific antibodies. CONCLUSION We have established a toolbox for measuring SARS-CoV-2-specific immunity against cell-bound virus antigens, which may be considered as an important addition to the armamentarium of SARS-CoV-2-specific diagnostic tests, allowing flexible and quick adaptation to new variants of concern.
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Affiliation(s)
- Al Nasar Ahmed Sehgal
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Jera Safran
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Bernhard Kratzer
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Pia Gattinger
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Robert B. Stieger
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Laszlo Musiejovsky
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Doris Trapin
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Paul Ettel
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Ulrike Körmöczi
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Arno Rottal
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Kristina Borochova
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Yulia Dorofeeva
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Inna Tulaeva
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
- Laboratory for Immunopathology, Department of Clinical Immunology and Allergology, Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Milena Weber
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Katharina Grabmeier-Pfistershammer
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
| | - Thomas Perkmann
- Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria;
| | - Ursula Wiedermann
- Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Rudolf Valenta
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
- Laboratory for Immunopathology, Department of Clinical Immunology and Allergology, Sechenov First Moscow State Medical University, 119991 Moscow, Russia
- NRC Institute of Immunology FMBA of Russia, 115478 Moscow, Russia
- Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
| | - Winfried F. Pickl
- Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria (J.S.); (R.B.S.)
- Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
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3
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Dahl L, Kotliar IB, Bendes A, Dodig-Crnković T, Fromm S, Elofsson A, Uhlén M, Sakmar TP, Schwenk JM. Multiplexed selectivity screening of anti-GPCR antibodies. SCIENCE ADVANCES 2023; 9:eadf9297. [PMID: 37134173 PMCID: PMC10156119 DOI: 10.1126/sciadv.adf9297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/31/2023] [Indexed: 05/05/2023]
Abstract
G protein-coupled receptors (GPCRs) control critical cellular signaling pathways. Therapeutic agents including anti-GPCR antibodies (Abs) are being developed to modulate GPCR function. However, validating the selectivity of anti-GPCR Abs is challenging because of sequence similarities among individual receptors within GPCR subfamilies. To address this challenge, we developed a multiplexed immunoassay to test >400 anti-GPCR Abs from the Human Protein Atlas targeting a customized library of 215 expressed and solubilized GPCRs representing all GPCR subfamilies. We found that ~61% of Abs tested were selective for their intended target, ~11% bound off-target, and ~28% did not bind to any GPCR. Antigens of on-target Abs were, on average, significantly longer, more disordered, and less likely to be buried in the interior of the GPCR protein than the other Abs. These results provide important insights into the immunogenicity of GPCR epitopes and form a basis for designing therapeutic Abs and for detecting pathological auto-Abs against GPCRs.
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Affiliation(s)
- Leo Dahl
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, 171 65 Solna, Sweden
| | - Ilana B. Kotliar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
- Tri-Institutional PhD Program in Chemical Biology, New York, NY 10065, USA
| | - Annika Bendes
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, 171 65 Solna, Sweden
| | - Tea Dodig-Crnković
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, 171 65 Solna, Sweden
| | - Samuel Fromm
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Arne Elofsson
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 171 65 Solna, Sweden
| | - Mathias Uhlén
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, 171 65 Solna, Sweden
| | - Thomas P. Sakmar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, 171 64 Solna, Sweden
| | - Jochen M. Schwenk
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, 171 65 Solna, Sweden
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4
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Guo XY, Gao XD, Fujita M. Sulfation of a FLAG tag mediated by SLC35B2 and TPST2 affects antibody recognition. PLoS One 2021; 16:e0250805. [PMID: 33951064 PMCID: PMC8099120 DOI: 10.1371/journal.pone.0250805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/14/2021] [Indexed: 11/30/2022] Open
Abstract
A FLAG tag consisting of DYKDDDDK is an epitope tag that is frequently and widely used to detect recombinant proteins of interest. In this study, we performed a CRISPR-based genetic screening to identify factors involved in the detection of a FLAG-tagged misfolded model protein at the cell surface. In the screening, SLC35B2, which encodes 3’-phosphoadenosine-5’-phosphosulfate transporter 1, was identified as the candidate gene. The detection of FLAG-tagged misfolded proteins at the cell surface was significantly increased in SLC35B2-knockout cells. Furthermore, protein tyrosine sulfation mediated by tyrosyl-protein sulfotransferase 2 (TPST2) suppressed FLAG-tagged protein detection. Localization analysis of the FLAG-tagged misfolded proteins confirmed that defects in tyrosine sulfation are only responsible for enhancing anti-FLAG staining on the plasma membrane but not inducing the localization change of misfolded proteins on the plasma membrane. These results suggest that a FLAG tag on the misfolded protein would be sulfated, causing a reduced detection by the M2 anti-FLAG antibody. Attention should be required when quantifying the FLAG-tagged proteins in the secretory pathway.
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Affiliation(s)
- Xin-Yu Guo
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
| | - Morihisa Fujita
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
- * E-mail:
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5
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Kim K, Park KM, Murray J, Kim K, Ryu SH. Direct Profiling the Post-Translational Modification Codes of a Single Protein Immobilized on a Surface Using Cu-free Click Chemistry. ACS CENTRAL SCIENCE 2018; 4:614-623. [PMID: 29806008 PMCID: PMC5968440 DOI: 10.1021/acscentsci.8b00114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Indexed: 06/08/2023]
Abstract
Combinatorial post-translational modifications (PTMs), which can serve as dynamic "molecular barcodes", have been proposed to regulate distinct protein functions. However, studies of combinatorial PTMs on single protein molecules have been hindered by a lack of suitable analytical methods. Here, we describe erasable single-molecule blotting (eSiMBlot) for combinatorial PTM profiling. This assay is performed in a highly multiplexed manner and leverages the benefits of covalent protein immobilization, cyclic probing with different antibodies, and single molecule fluorescence imaging. Especially, facile and efficient covalent immobilization on a surface using Cu-free click chemistry permits multiple rounds (>10) of antibody erasing/reprobing without loss of antigenicity. Moreover, cumulative detection of coregistered multiple data sets for immobilized single-epitope molecules, such as HA peptide, can be used to increase the antibody detection rate. Finally, eSiMBlot enables direct visualization and quantitative profiling of combinatorial PTM codes at the single-molecule level, as we demonstrate by revealing the novel phospho-codes of ligand-induced epidermal growth factor receptor. Thus, eSiMBlot provides an unprecedentedly simple, rapid, and versatile platform for analyzing the vast number of combinatorial PTMs in biological pathways.
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Affiliation(s)
- Kyung
Lock Kim
- Department of Life Sciences and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
| | - Kyeng Min Park
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
- Department
of Nanomaterials Science and Engineering, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - James Murray
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
| | - Kimoon Kim
- Department of Life Sciences and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center
for Self-Assembly and Complexity, Institute
for Basic Science, Pohang 37673, Republic of Korea
| | - Sung Ho Ryu
- Department of Life Sciences and Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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Imaimatsu K, Fujii W, Hiramatsu R, Miura K, Kurohmaru M, Kanai Y. CRISPR/Cas9-mediated knock-in of the murine Y chromosomal Sry gene. J Reprod Dev 2018; 64:283-287. [PMID: 29657232 PMCID: PMC6021606 DOI: 10.1262/jrd.2017-161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mammalian zygote-mediated genome editing via the clustered regularly interspaced short palindromic repeats/CRISPR-associated endonuclease 9 (CRISPR/Cas9) system is widely used to generate
genome-modified animals. This system allows for the production of loss-of-function mutations in various Y chromosome genes, including Sry, in mice. Here, we report the
establishment of a CRISPR-Cas9-mediated knock-in line of Flag-tag sequences into the Sry locus at the C-terminal coding end of the Y chromosome
(YSry-flag). In the F1 and successive generations, all male pups carrying the YSry-flag chromosome had normal testis differentiation
and proper spermatogenesis at maturity, enabling complete fertility and the production of viable offspring. To our knowledge, this study is the first to produce a stable Sry
knock-in line at the C-terminal region, highlighting a novel approach for examining the significance of amino acid changes at the naive Sry locus in mammals.
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Affiliation(s)
- Kenya Imaimatsu
- Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan
| | - Wataru Fujii
- Department of Animal Resource Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Ryuji Hiramatsu
- Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kento Miura
- Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan
| | - Masamichi Kurohmaru
- Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yoshiakira Kanai
- Department of Veterinary Anatomy, The University of Tokyo, Tokyo 113-8657, Japan
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Charest-Morin X, Poubelle PE, Marceau F. Production and evaluation of parathyroid hormone receptor 1 ligands with intrinsic or assembled peroxidase domains. Sci Rep 2017; 7:13099. [PMID: 29026164 PMCID: PMC5638942 DOI: 10.1038/s41598-017-13548-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 09/26/2017] [Indexed: 12/28/2022] Open
Abstract
Parathyroid hormone (PTH) can be C-terminally extended without significant affinity loss for the PTH1 receptor (PTHR1). We developed fusion protein ligands with enzymatic activity to probe PTHR1s at the cell surface. Two fusion proteins were generated by linking PTH to the N-terminus of either horseradish peroxidase (PTH-HRP) or the genetically modified soybean peroxidase APEX2 (PTH-APEX2). Alternatively, myc-tagged PTH (PTH-myc) was combined with antibodies, some of which HRP-conjugated, in the extracellular fluid. The three PTH-fusion proteins were produced as conditioned mediums (CM) by transfected producer HEK 293a cells. Binding of receptor-bound enzymatic ligands was revealed using widely available substrate/co-substrate systems. The stimulation of recipient HEK 293a expressing PTHR1s with the PTH-myc/antibodies combination or with PTH-APEX2 supported the histochemical or luminescent detection of recombinant PTHR1s (TrueBlueTM or luminol-based reagent). The PTH-HRP construction was the most sensitive and supported all tested peroxidase co-substrates (TrueBlueTM, tetramethylbenzidine (TMB), luminol, biotin-phenol with streptavidin-Qdots); the 3 latter schemes identified endogenous PTHR1 in the osteoblastic HOS cell line. The specificity of the fusion protein binding to PTHR1 was determined by its competition with an excess of PTH1–34. Bifunctional ligands possessing enzymatic activity detect intact receptors with various possible applications, including the screening of drugs that compete for receptor binding.
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Affiliation(s)
- Xavier Charest-Morin
- Division of Infectious Disease and Immunity, CHU de Québec-Université Laval, Quebec City, QC, G1V 4G2, Canada
| | - Patrice E Poubelle
- Division of Infectious Disease and Immunity, CHU de Québec-Université Laval, Quebec City, QC, G1V 4G2, Canada
| | - François Marceau
- Division of Infectious Disease and Immunity, CHU de Québec-Université Laval, Quebec City, QC, G1V 4G2, Canada.
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Finlay DB, Cawston EE, Grimsey NL, Hunter MR, Korde A, Vemuri VK, Makriyannis A, Glass M. Gα s signalling of the CB 1 receptor and the influence of receptor number. Br J Pharmacol 2017; 174:2545-2562. [PMID: 28516479 PMCID: PMC5513864 DOI: 10.1111/bph.13866] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/30/2017] [Accepted: 05/09/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND PURPOSE CB1 receptor signalling is canonically mediated through inhibitory Gαi proteins, but occurs through other G proteins under some circumstances, Gαs being the most characterized secondary pathway. Determinants of this signalling switch identified to date include Gαi blockade, CB1 /D2 receptor co-stimulation, CB1 agonist class and cell background. Hence, we examined the effects of receptor number and different ligands on CB1 receptor signalling. EXPERIMENTAL APPROACH CB1 receptors were expressed in HEK cells at different levels, and signalling characterized for cAMP by real-time BRET biosensor -CAMYEL - and for phospho-ERK by AlphaScreen. Homogenate and whole cell radioligand binding assays were performed to characterize AM6544, a novel irreversible CB1 receptor antagonist. KEY RESULTS In HEK cells expressing high levels of CB1 receptors, agonist treatment stimulated cAMP, a response not known to be mediated by receptor number. Δ9 -THC and BAY59-3074 increased cAMP only in high-expressing cells pretreated with pertussis toxin, and agonists demonstrated more diverse signalling profiles in the stimulatory pathway than the canonical inhibitory pathway. Pharmacological CB1 receptor knockdown and Gαi 1 supplementation restored canonical Gαi signalling to high-expressing cells. Constitutive signalling in both low- and high-expressing cells was Gαi -mediated. CONCLUSION AND IMPLICATIONS CB1 receptor coupling to opposing G proteins is determined by both receptor and G protein expression levels, which underpins a mechanism for non-canonical signalling in a fashion consistent with Gαs signalling. CB1 receptors mediate opposite consequences in endpoints such as tumour viability depending on expression levels; our results may help to explain such effects at the level of G protein coupling.
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Affiliation(s)
- David B Finlay
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Erin E Cawston
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Natasha L Grimsey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Morag R Hunter
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Anisha Korde
- Center for Drug DiscoveryNortheastern UniversityBostonMAUSA
| | - V Kiran Vemuri
- Center for Drug DiscoveryNortheastern UniversityBostonMAUSA
| | | | - Michelle Glass
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
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OCT4B1 Regulates the Cellular Stress Response of Human Dental Pulp Cells with Inflammation. BIOMED RESEARCH INTERNATIONAL 2017; 2017:2756891. [PMID: 28473980 PMCID: PMC5394356 DOI: 10.1155/2017/2756891] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 03/11/2017] [Accepted: 03/16/2017] [Indexed: 11/17/2022]
Abstract
Introduction. Infection and apoptosis are combined triggers for inflammation in dental tissues. Octamer-binding transcription factor 4-B1 (OCT4B1), a novel spliced variant of OCT4 family, could respond to the cellular stress and possess antiapoptotic property. However, its specific role in dental pulpitis remains unknown. Methods. To investigate the effect of OCT4B1 on inflammation of dental pulp cells (DPCs), its expression in inflamed dental pulp tissues and DPCs was examined by in situ hybridization, real-time PCR, and FISH assay. OCT4B1 overexpressed DPCs model was established, confirmed by western blot and immunofluorescence staining, and then stimulated with Lipopolysaccharide (LPS). Apoptotic rate was determined by Hoechst/PI staining and FACS. Cell survival rate was calculated by CCK8 assay. Results. In situ hybridization, real-time PCR, and FISH assay revealed that OCT4B1 was extensively expressed in inflamed dental pulp tissues and DPCs with LPS stimulation. Western blot and immunofluorescence staining showed the expression of OCT4B1 and OCT4B increased after OCT4B1 transfection. Hoechst/PI staining and FACS demonstrated that less red/blue fluorescence was detected and apoptotic percentage decreased (3.45%) after transfection. CCK8 demonstrated that the survival rate of pCDH-OCT4B1-flag cells increased. Conclusions. OCT4B1 plays an essential role in inflammation and apoptosis of DPCs. OCT4B might operate synergistically with OCT4B1 to reduce apoptosis.
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