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Maryu G, Miura H, Uda Y, Komatsubara AT, Matsuda M, Aoki K. Live-cell Imaging with Genetically Encoded Protein Kinase Activity Reporters. Cell Struct Funct 2018; 43:61-74. [DOI: 10.1247/csf.18003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Gembu Maryu
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University
- Division of Quantitative Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences
| | - Haruko Miura
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University
- Division of Quantitative Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences
| | - Youichi Uda
- Division of Quantitative Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences
- Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University
| | - Akira T. Komatsubara
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University
- Division of Quantitative Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences
| | - Michiyuki Matsuda
- Laboratory of Bioimaging and Cell Signaling, Graduate School of Biostudies, Kyoto University
- Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University
- Imaging Platform for Spatio-Temporal Information, Graduate School of Medicine, Kyoto University
| | - Kazuhiro Aoki
- Division of Quantitative Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences
- Department of Basic Biology, Faculty of Life Science, SOKENDAI (Graduate University for Advanced Studies)
- Imaging Platform for Spatio-Temporal Information, Graduate School of Medicine, Kyoto University
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Taleb N, Coriati A, Khazzaka C, Bayonne J, Messier V, Rabasa-Lhoret R. Stability of Commercially Available Glucagon Formulation for Dual-Hormone Artificial Pancreas Clinical Use. Diabetes Technol Ther 2017; 19:589-594. [PMID: 28846447 PMCID: PMC5653137 DOI: 10.1089/dia.2017.0204] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Available glucagon formulations are approved for immediate use after reconstitution for severe hypoglycemia emergency treatment. However, they are used in dual-hormone artificial pancreas (insulin and glucagon) studies through subcutaneous infusion pumps over 24 h. Chemical and physical stability of such glucagon use have not been reported in a comprehensive manner. MATERIALS AND METHODS Recombinant Glucagon DNA (Eli Lilly) was used. Compatibility and sterility of glucagon delivery through subcutaneous pump systems were verified. Glucagon degradation through liquid chromatography with tandem mass spectrometry (LC-MS/MS), fibrillation using intrinsic tryptophan fluorescence shift, and bioactivity through a cell-protein kinase A-based fluorescent bioassay were assessed over a range of different physical conditions (temperature, movement, and air bubbles). RESULTS Subcutaneous infusion pump systems administered glucagon in sterile conditions and with comparable accuracy to insulin delivery; mean absolute relative difference of actual versus expected weights were 1.2% ± 1.1% for glucagon and 1.1% ± 0.5% for insulin (P = 0.9). In comparison to freshly reconstituted samples, glucagon analyzed through LC-MS/MS was intact at 93.0% ± 7.0% after 24 h (P = 0.42) and 83.04% ± 6.0% after 48 h (P = 0.02) of incubation in pumps at 32°C. Peak wavelengths for Trp fluorescence did not differ from samples exposed to air bubbles or movement whether incubated (in infusion sets for 24 h at 32°) immediately or 24- and 48-h poststorage at 4°C (P = 0.10, 0.70 and 0.80, respectively) and no significant differences in bioactivity (shifts in EC50) were found for the same conditions (P = 0.13, 0.83, and 0.63). CONCLUSION Available glucagon formulations are chemically and physically stable, as well as compatible with delivery through subcutaneous infusion pumps over 24 h and can be used in long-term clinical trials.
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Affiliation(s)
- Nadine Taleb
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
- Division of Biomedical Sciences, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Adèle Coriati
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
| | | | - Jonathan Bayonne
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
| | - Virginie Messier
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
| | - Rémi Rabasa-Lhoret
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
- Montreal Diabetes Research Center, Québec, Canada
- Department of Nutrition, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
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The opioid receptor triple agonist DPI-125 produces analgesia with less respiratory depression and reduced abuse liability. Acta Pharmacol Sin 2017; 38:977-989. [PMID: 28502978 DOI: 10.1038/aps.2017.14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/23/2017] [Indexed: 12/23/2022] Open
Abstract
Opioid analgesics remain the first choice for the treatment of moderate to severe pain, but they are also notorious for their respiratory depression and addictive effects. This study focused on the pharmacology of a novel opioid receptor mixed agonist DPI-125 and attempted to elucidate the relationship between the δ-, μ- and κ-receptor potency ratio and respiratory depression and abuse liability. Five diarylmethylpiperazine compounds (DPI-125, DPI-3290, DPI-130, KUST202 and KUST13T02) were selected for this study. PKA fluorescence redistribution assays in CHO cells individually expressing δ-, μ- or κ-receptors were used to measure the agonist potency. The respiratory safety profiles were estimated in rats by the ratio of ED50 (pCO2 increase)/ED50 (antinociception). The abuse liability of DPI-125 was evaluated with a self-administration model in rhesus monkeys. The observed agonist potencies of DPI-125 for δ-, μ- and κ-opioid receptors were 4.29±0.36, 11.10±3.04, and 16.57±4.14 nmol/L, respectively. The other four compounds were also mixed agonists with varying potencies. DPI-125 exhibited a high respiratory safety profile, clearly related to its high δ-receptor potency. The ratio of the EC50 potencies for the μ- and δ-receptors was found to be positively correlated with the respiratory safety ratio. DPI-125 has similar potencies for μ- and κ-receptors, which is likely the reason for its reduced abuse potential. Our results demonstrate that the opioid receptor mixed agonist DPI-125 is safer and less addictive than traditional μ-agonist analgesics. These findings suggest that the development of δ>μ∼κ opioid receptor mixed agonists is feasible, and such compounds could represent a promising class of potent analgesics with wider therapeutic windows.
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Manoharan GB, Enkvist E, Kasari M, Viht K, Zenn M, Prinz A, Filhol O, Herberg FW, Uri A. FRET-based screening assay using small-molecule photoluminescent probes in lysate of cells overexpressing RFP-fused protein kinases. Anal Biochem 2015; 481:10-7. [PMID: 25866074 DOI: 10.1016/j.ab.2015.04.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/16/2015] [Accepted: 04/07/2015] [Indexed: 01/08/2023]
Abstract
An assay was developed for the characterization of protein kinase inhibitors in lysates of mammalian cells based on the measurement of FRET between overexpressed red fluorescent protein (TagRFP)-fused protein kinases (PKs) and luminophore-labeled small-molecule inhibitors (ARC-Photo probes). Two types of the assay, one using TagRFP as the photoluminescence donor together with ARC-Photo probes containing a red fluorophore dye as acceptor, and the other using TagRFP as the acceptor fluorophore in combination with a terbium cryptate-based long-lifetime photoluminescence donor, were used for FRET-based measurements in lysates of the cells overexpressing TagRFP-fused PKs. The second variant of the assay enabled the performance of the measurements under time-resolved conditions that led to substantially higher values of the signal/background ratio and further improved the reliability of the assay.
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Affiliation(s)
| | - Erki Enkvist
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Marje Kasari
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Kaido Viht
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Michael Zenn
- Department of Biochemistry, University of Kassel, 34132 Kassel, Germany
| | - Anke Prinz
- Department of Biochemistry, University of Kassel, 34132 Kassel, Germany
| | - Odile Filhol
- Institut National de la Santé et de la Recherche Médicale, U1036, Grenoble, France; Commisariat à l'Energie Atomique, Institute of Life Sciences Research and Technologies, Biology of Cancer and Infection, Grenoble, France; Université Grenoble Alpes, Unité Mixte de Recherche, S1036, Grenoble, France
| | | | - Asko Uri
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia.
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Fontaine F, Overman J, François M. Pharmacological manipulation of transcription factor protein-protein interactions: opportunities and obstacles. CELL REGENERATION (LONDON, ENGLAND) 2015; 4:2. [PMID: 25848531 PMCID: PMC4365538 DOI: 10.1186/s13619-015-0015-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 02/10/2015] [Indexed: 12/19/2022]
Abstract
Much research on transcription factor biology and their genetic pathways has been undertaken over the last 30 years, especially in the field of developmental biology and cancer. Yet, very little is known about the molecular modalities of highly dynamic interactions between transcription factors, genomic DNA, and protein partners. Methodological breakthroughs such as RNA-seq (RNA-sequencing), ChIP-seq (chromatin immunoprecipitation sequencing), RIME (rapid immunoprecipitation mass spectrometry of endogenous proteins), and single-molecule imaging will dramatically accelerate the discovery rate of their molecular mode of action in the next few years. From a pharmacological viewpoint, conventional methods used to target transcription factor activity with molecules mimicking endogenous ligands fail to achieve high specificity and are limited by a lack of identification of new molecular targets. Protein-protein interactions are likely to represent one of the next major classes of therapeutic targets. Transcription factors, known to act mostly via protein-protein interaction, may well be at the forefront of this type of drug development. One hurdle in this field remains the difficulty to collate structural data into meaningful information for rational drug design. Another hurdle is the lack of chemical libraries meeting the structural requirements of protein-protein interaction disruption. As more attempts at modulating transcription factor activity are undertaken, valuable knowledge will be accumulated on the modality of action required to modulate transcription and how these findings can be applied to developing transcription factor drugs. Key discoveries will spawn into new therapeutic approaches not only as anticancer targets but also for other indications, such as those with an inflammatory component including neurodegenerative disorders, diabetes, and chronic liver and kidney diseases.
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Affiliation(s)
- Frank Fontaine
- Division of Genomics of Development and Diseases, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St Lucia, QLD 4072 Australia
| | - Jeroen Overman
- Division of Genomics of Development and Diseases, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St Lucia, QLD 4072 Australia
| | - Mathias François
- Division of Genomics of Development and Diseases, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St Lucia, QLD 4072 Australia
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Jackson MA, Caputo N, Castle JR, David LL, Roberts CT, Ward WK. Stable liquid glucagon formulations for rescue treatment and bi-hormonal closed-loop pancreas. Curr Diab Rep 2012; 12:705-10. [PMID: 22972416 PMCID: PMC3970213 DOI: 10.1007/s11892-012-0320-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Small doses of glucagon given subcutaneously in the research setting by an automated system prevent most cases of hypoglycemia in persons with diabetes. However, glucagon is very unstable and cannot be kept in a portable pump. Glucagon rapidly forms amyloid fibrils, even within the first day after reconstitution. Aggregation eventually leads to insoluble gels, which occlude pump catheters. Fibrillation occurs rapidly at acid pH, but is absent or minimal at alkaline pH values of ~10. Glucagon also degrades over time; this problem is greater at alkaline pH. Several studies suggest that its primary degradative pathway is deamidation, which results in a conversion of asparagine to aspartic acid. A cell-based assay for glucagon bioactivity that assesses glucagon receptor (GluR) activation can screen promising glucagon formulations. However, mammalian hepatocytes are usually problematic as they can lose GluR expression during culture. Assays for cyclic AMP (cAMP) or its downstream effector, protein kinase A (PKA), in engineered cell systems, are more reliable and suitable for inexpensive, high-throughput assessment of bioactivity.
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Affiliation(s)
- Melanie A Jackson
- Oregon Health and Science University (OHSU), 3181 SW Sam Jackson Park Road, OP05DC, Portland, OR 97239, USA.
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Stimulus-induced translocation of the protein kinase A catalytic subunit to the apical membrane in blowfly salivary glands. Cell Tissue Res 2008; 335:657-62. [PMID: 18766382 DOI: 10.1007/s00441-008-0673-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022]
Abstract
Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca(2+) pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H(+)-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H(+)-ATPase, which is enriched in this membrane domain, is a target protein for PKA.
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Gupta S, Indelicato SR, Jethwa V, Kawabata T, Kelley M, Mire-Sluis AR, Richards SM, Rup B, Shores E, Swanson SJ, Wakshull E. Recommendations for the design, optimization, and qualification of cell-based assays used for the detection of neutralizing antibody responses elicited to biological therapeutics. J Immunol Methods 2007; 321:1-18. [PMID: 17307199 DOI: 10.1016/j.jim.2006.12.004] [Citation(s) in RCA: 192] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 11/29/2006] [Accepted: 12/06/2006] [Indexed: 11/25/2022]
Abstract
The administration of biological therapeutics can evoke some level of immune response to the drug product in the receiving subjects. An immune response comprised of neutralizing antibodies can lead to loss of efficacy or potentially more serious clinical sequelae. Therefore, it is important to monitor the immunogenicity of biological therapeutics throughout the drug product development cycle. Immunoassays are typically used to screen for the presence and development of anti-drug product antibodies. However, in-vitro cell-based assays prove extremely useful for the characterization of immunoassay-positive samples to determine if the detected antibodies have neutralizing properties. This document provides scientific recommendations based on the experience of the authors for the development of cell-based assays for the detection of neutralizing antibodies in non-clinical and clinical studies.
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Affiliation(s)
- Shalini Gupta
- Clinical Immunology, Amgen Inc., Thousand Oaks, CA 91320, USA.
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Tang Y, Li X, He J, Lu J, Diwu Z. Real-time and high throughput monitoring of cAMP in live cells using a fluorescent membrane potential-sensitive dye. Assay Drug Dev Technol 2007; 4:461-71. [PMID: 16945018 DOI: 10.1089/adt.2006.4.461] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adenosine-3',5'-cyclic monophosphate (cAMP) conveys the signals from G-protein coupled receptors (GPCRs) and regulates a variety of downstream cellular events. However, there are few robust assays available for measuring cAMP in live cells. Most of the existing cAMP assays require cell lysis and/or have relatively low throughput. We report a live cell-based cAMP assay that has been developed to record the real-time changes in intracellular cAMP. By employing a mutated cyclic-nucleotide-gated ion channel (CNGC) as the cAMP biosensor, the change of cAMP level is coupled to the change of transmembrane potential that is measured through a new fluorescent membrane potential (MP)-sensitive dye, HLB 021-152. We have successfully used HLB 021-152 for homogeneously monitoring cAMP stimulations in live cells under both serum-containing and serum-free environments. Upon stimulating the endogenous or heterogenous GPCRs on CNGC-cloned human embryonic kidney 293 cells with agonists, the fluorescence signal of HLB 021-152 increases rapidly. It has much greater assay dynamic range than DiSBAC2(3), the existing "gold standard" dye for measuring cellular MP. This new MP dye can be readily formulated for high throughput screening of GPCR modulators either with serum or without serum.
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Affiliation(s)
- Yi Tang
- AnaSpec Inc., San Jose, CA 95131, USA
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Liu H, Zhang H, Iles KE, Rinna A, Merrill G, Yodoi J, Torres M, Forman HJ. The ADP-stimulated NADPH oxidase activates the ASK-1/MKK4/JNK pathway in alveolar macrophages. Free Radic Res 2007; 40:865-74. [PMID: 17015265 PMCID: PMC2713795 DOI: 10.1080/10715760600758514] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The role of H2O2 as a second messenger in signal transduction pathways is well established. We show here that the NADPH oxidase-dependent production of O2*(-) and H2O2 or respiratory burst in alveolar macrophages (AM) (NR8383 cells) is required for ADP-stimulated c-Jun phosphorylation and the activation of JNK1/2, MKK4 (but not MKK7) and apoptosis signal-regulating kinase-1 (ASK1). ASK1 binds only to the reduced form of thioredoxin (Trx). ADP induced the dissociation of ASK1/Trx complex and thus resulted in ASK1 activation, as assessed by phosphorylation at Thr845, which was enhanced after treatment with aurothioglucose (ATG), an inhibitor of Trx reductase. While dissociation of the complex implies Trx oxidation, protein electrophoretic mobility shift assay detected oxidation of Trx only after bolus H2O2 but not after ADP stimulation. These results demonstrate that the ADP-stimulated respiratory burst activated the ASK1-MKK4-JNK1/c-Jun signaling pathway in AM and suggest that transient and localized oxidation of Trx by the NADPH oxidase-mediated generation of H2O2 may play a critical role in ASK1 activation and the inflammatory response.
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Affiliation(s)
- Honglei Liu
- School of Natural Sciences, University of California Merced, Merced, CA 95340, USA
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Samuelsen JT, Schwarze PE, Huitfeldt HS, Thrane EV, Låg M, Refsnes M, Skarpen E, Becher R. Regulation of rat alveolar type 2 cell proliferation in vitro involves type II cAMP-dependent protein kinase. Am J Physiol Lung Cell Mol Physiol 2006; 292:L232-9. [PMID: 16980378 DOI: 10.1152/ajplung.00049.2006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To elucidate the role of cAMP and different cAMP-dependent protein kinases (PKA; A-kinase) in lung cell proliferation, we investigated rat alveolar type 2 cell proliferation in relation to activation or inhibition of PKA and PKA regulatory subunits (RIIalpha and RIalpha). Both the number of proliferating type 2 cells and the level of different regulatory subunits varied during 7 days of culture. The cells exhibited a distinct peak of proliferation after 5 days of culture. This proliferation peak was preceded by a rise in RIIalpha protein level. In contrast, an inverse relationship between RIalpha and type 2 cell proliferation was noted. Activation of PKA increased type 2 cell proliferation if given at peak RIIalpha expression. Furthermore, PKA inhibitors lowered the rate of proliferation only when a high RII level was observed. An antibody against the anchoring region of RIIalpha showed cell cycle-dependent binding in contrast to antibodies against other regions, possibly related to altered binding to A-kinase anchoring protein. Following activation of PKA, relocalization of RIIalpha was confirmed by immunocytochemistry. In conclusion, it appears that activation of PKA II is important in regulation of alveolar type 2 cell proliferation.
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Affiliation(s)
- Jan T Samuelsen
- Division of Environmental Medicine, Norwegian Institute of Public Health, Oslo, Norway.
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Prinz A, Diskar M, Herberg FW. Application of bioluminescence resonance energy transfer (BRET) for biomolecular interaction studies. Chembiochem 2006; 7:1007-12. [PMID: 16755626 DOI: 10.1002/cbic.200600048] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Anke Prinz
- Kassel University, Department of Biochemistry, Kassel, Germany
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Abstract
Traditional screening paradigms often focus on single targets. To facilitate drug discovery in the more complex physiological environment of a cell or organism, powerful cellular imaging systems have been developed. The emergence of these detection technologies allows the quantitative analysis of cellular events and visualization of relevant cellular phenotypes. Cellular imaging facilitates the integration of complex biology into the screening process, and addresses both high-content and high-throughput needs. This review describes how cellular imaging technologies contribute to the drug discovery process.
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Affiliation(s)
- Paul Lang
- Department of Molecular Screening & Cellular Pharmacology, Serono Pharmaceutical Research Institute, 14 chemin des Aulx, 1228 Plan-les-Ouates, Switzerland.
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Prinz A, Diskar M, Erlbruch A, Herberg FW. Novel, isotype-specific sensors for protein kinase A subunit interaction based on bioluminescence resonance energy transfer (BRET). Cell Signal 2006; 18:1616-25. [PMID: 16524697 DOI: 10.1016/j.cellsig.2006.01.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 01/11/2006] [Indexed: 11/26/2022]
Abstract
Homogeneous protein-protein interaction assays without the need of a separation step are an essential tool to unravel signal transduction events in live cells. We have established an isoform specific protein kinase A (PKA) subunit interaction assay based on bioluminescence resonance energy transfer (BRET). Tagging human Ralpha(I)-, Ralpha(II)-, as well as Calpha-subunits of PKA with Renilla luciferase (Rluc) as the bioluminescent donor or with green fluorescent protein (GFP2) as the energy acceptor, respectively, allows to directly probe PKA subunit interaction in living cells as well as in total cell extracts in order to study side by side PKA type I versus type II holoenzyme dynamics. Several novel, genetically encoded cAMP sensors and-for the first time PKA type I sensors-were generated. When C- and R-subunits are assembled to the respective holoenzyme complexes inside the cell, BRET occurs with a signal up to three times above the background. An increase of endogenous cAMP levels as well as treatment with the cAMP analog 8-Br-cAMP is reflected by a dose-dependent BRET signal reduction in cells expressing wild type proteins. In contrast to type II, the dissociation of the PKA type I holoenzyme complex was never complete in cells with maximally elevated cAMP levels. Both sensors dissociated completely upon treatment with 8-Br-cAMP after cell lysis, consistent with in vitro activation assays using holoenzymes assembled from purified PKA subunits. Interestingly, incubation of cells with the PKA antagonist Rp-8-Br-cAMPS leads to a significant BRET signal increase in cells expressing PKA type I or type II isoforms, indicating a stabilization of the holoenzyme complexes in vivo. Mutant RI subunits with reduced (hRIalpha-R210K) or abolished (hRIalpha-G200E/G324E) cAMP binding capability were studied to quantify maximal signal to noise ratios for the RI-BRET sensor. Utilizing BRET we demonstrate that PKA type II holoenzyme was rendered insensitive to beta-adrenergic receptor stimulation with isoproterenol when anchoring to the plasma membrane of COS-7 cells was disrupted by either using Ht31 peptide or by depletion of membrane cholesterol.
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Affiliation(s)
- Anke Prinz
- University of Kassel, Department of Biochemistry, Heinrich Plett Str. 40, D-34132 Kassel, Germany.
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Pagliaro L, Felding J, Audouze K, Nielsen SJ, Terry RB, Krog-Jensen C, Butcher S. Emerging classes of protein–protein interaction inhibitors and new tools for their development. Curr Opin Chem Biol 2004; 8:442-9. [PMID: 15288255 DOI: 10.1016/j.cbpa.2004.06.006] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein-protein interactions play a key role in the signal transduction pathways that regulate cellular function. Three years ago, few descriptions of small molecule protein-protein interaction inhibitors (SMPPIIs) existed in the literature. Today, the number of examples of both the biology and chemistry of such interaction inhibitors is growing rapidly. This growth occurs at the convergence of medicinal chemistry, signaling biology and novel assay technology for profiling emerging compound classes and modes of action. Protein translocation assays provide a unique new tool for identifying, profiling, and optimizing SMPPIIs. This review summarizes recent work in the field, and outlines future developments we can anticipate.
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Affiliation(s)
- Len Pagliaro
- BioImage A/S, Moerkhoej Bygade 28, 2860, Soeborg, Copenhagen, Denmark.
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