1
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Kovalová A, Prouza V, Zavřel M, Hájek M, Dzijak R, Magdolenová A, Pohl R, Voburka Z, Parkan K, Vrabel M. Selection of Galectin-Binding Ligands from Synthetic Glycopeptide Libraries. Chempluschem 2024; 89:e202300567. [PMID: 37942669 DOI: 10.1002/cplu.202300567] [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: 10/06/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/10/2023]
Abstract
Galectins, a class of carbohydrate-binding proteins, play a crucial role in various physiological and disease processes. Therefore, the identification of ligands that efficiently bind these proteins could potentially lead to the development of new therapeutic compounds. In this study, we present a method that involves screening synthetic click glycopeptide libraries to identify lectin-binding ligands with low micromolar affinity. Our methodology, initially optimized using Concanavalin A, was subsequently applied to identify binders for the therapeutically relevant galectin 1. Binding affinities were assessed using various methods and showed that the selected glycopeptides exhibited enhanced binding potency to the target lectins compared to the starting sugar moieties. This approach offers an alternative means of discovering galectin-binding ligands as well as other carbohydrate-binding proteins, which are considered important therapeutic targets.
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Affiliation(s)
- Anna Kovalová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Vít Prouza
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
- Department of Chemistry of Natural Compounds, University of Chemistry and Technology Prague, Technická 5, Prague, Czech Republic
| | - Martin Zavřel
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Miroslav Hájek
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Rastislav Dzijak
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Alžbeta Magdolenová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Radek Pohl
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Zdeněk Voburka
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
| | - Kamil Parkan
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
- Department of Chemistry of Natural Compounds, University of Chemistry and Technology Prague, Technická 5, Prague, Czech Republic
| | - Milan Vrabel
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16000, Prague, Czech Republic
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2
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Paul AR, Falsaperna M, Lavender H, Garrett MD, Serpell CJ. Selection of optimised ligands by fluorescence-activated bead sorting. Chem Sci 2023; 14:9517-9525. [PMID: 37712023 PMCID: PMC10498682 DOI: 10.1039/d3sc03581f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 08/11/2023] [Indexed: 09/16/2023] Open
Abstract
The chemistry of aptamers is largely limited to natural nucleotides, and although modifications of nucleic acids can enhance target aptamer affinity, there has not yet been a technology for selecting the right modifications in the right locations out of the vast number of possibilities, because enzymatic amplification does not transmit sequence-specific modification information. Here we show the first method for the selection of specific nucleoside modifications that increase aptamer binding efficacy, using the oncoprotein EGFR as a model target. Using fluorescence-activated bead sorting (FABS), we have successfully selected optimized aptamers from a library of >65 000 variations. Hits were identified by tandem mass spectrometry and validated by using an EGFR binding assay and computational docking studies. Our results provide proof of concept for this novel strategy for the selection of chemically optimised aptamers and offer a new method for rapidly synthesising and screening large aptamer libraries to accelerate diagnostic and drug discovery.
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Affiliation(s)
- Alexandra R Paul
- School of Chemistry and Forensic Sciences, Division of Natural Sciences, University of Kent Canterbury CT2 7NH UK
| | - Mario Falsaperna
- School of Chemistry and Forensic Sciences, Division of Natural Sciences, University of Kent Canterbury CT2 7NH UK
| | - Helen Lavender
- Avvinity Therapeutics 66 Prescot Street London E1 8NN UK
| | - Michelle D Garrett
- School of Biosciences, Division of Natural Sciences, University of Kent Canterbury CT2 7NJ UK
| | - Christopher J Serpell
- School of Chemistry and Forensic Sciences, Division of Natural Sciences, University of Kent Canterbury CT2 7NH UK
- School of Pharmacy, University College London London WC1N 1AX UK
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3
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Maresh ME, Zerfas BL, Wuthrich BS, Trader DJ. Identification of a covalent binder to the oncoprotein gankyrin using a NIR-Based OBOC screening method. RSC Adv 2021; 11:12794-12801. [PMID: 35423814 PMCID: PMC8697547 DOI: 10.1039/d0ra10976b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/23/2021] [Indexed: 11/29/2022] Open
Abstract
Despite huge advancements in the process of synthesizing small molecules as part of one-bead-one-compound (OBOC) libraries, progress lags in the ability to screen these libraries against proteins of interest. Recently, we developed a method to screen OBOC libraries in which a target protein is labeled with a near-infrared (NIR) range fluorophore. The labeled protein incubates with beads of a library in a 96-well plate, then the plate is imaged for fluorescence. Fluorescence intensities produced by the labeled protein binding the bead can be quantitated and provide a basis to rank hits. Here, we present an application of this technique by screening the oncoprotein gankyrin against a 343-member peptoid library. The library was composed of four positions occupied by one of seven amines. In the third position, an amine that facilitates covalent binding via a sulfonyl fluoride moiety was incorporated. After screening for gankyrin binders twice, ten structures showed overlap in the types of amines present at each position. These initial hits were validated with an in-gel fluorescence assay in which the labeled ligands covalently interacted with purified gankyrin. Excitingly, one peptoid was validated from this analysis. This hit was also shown to bind gankyrin in the presence of HEK 293T lysate. Results from this study demonstrate successful use of our screening method to quickly identify quality binders to a target protein of interest.
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Affiliation(s)
- Marianne E Maresh
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University West Lafayette Indiana 47907 USA
| | - Breanna L Zerfas
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University West Lafayette Indiana 47907 USA
| | - Brice S Wuthrich
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University West Lafayette Indiana 47907 USA
| | - Darci J Trader
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University West Lafayette Indiana 47907 USA
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4
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Krause T, Röckendorf N, Meckelein B, Sinnecker H, Schwager C, Möckel S, Jappe U, Frey A. IgE Epitope Profiling for Allergy Diagnosis and Therapy - Parallel Analysis of a Multitude of Potential Linear Epitopes Using a High Throughput Screening Platform. Front Immunol 2020; 11:565243. [PMID: 33117349 PMCID: PMC7561404 DOI: 10.3389/fimmu.2020.565243] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 09/08/2020] [Indexed: 12/22/2022] Open
Abstract
Immunoglobulin E (IgE) is pivotal for manifestation and persistence of most immediate-type allergies and some asthma phenotypes. Consequently, IgE represents a crucial target for both, diagnostic purposes as well as therapeutic approaches. In fact, allergen-specific immunotherapy – aiming to re-route an IgE-based inflammatory response into an innocuous immune reaction against the allergen – is the only curative approach for IgE-mediated allergic diseases known so far. However, this requires the cognate allergen to be known. Unfortunately, even in well-characterized allergics or asthmatics, often just a small fraction of total IgE can be assigned to specific target allergens. To overcome this knowledge gap, we have devised an analytical platform for unbiased IgE target epitope detection. The system relies on chemically produced random peptide libraries immobilized on polystyrene beads (“one-bead-one-compound (OBOC) libraries”) capable to present millions of different peptide motifs simultaneously to immunoglobulins from biological samples. Beads binding IgE are highlighted with a fluorophore-labeled anti-IgE antibody allowing fluorescence-based detection and isolation of positives, which then can be characterized by peptide sequencing. Setting-up this platform required an elaborate optimization process including proper choice of background suppressants, secondary antibody and fluorophore label as well as incubation conditions. For optimal performance our procedure involves a sophisticated pre-adsorption step to eliminate beads that react nonspecifically with anti-IgE secondary antibodies. This step turned out to be important for minimizing detection of “false positive” motifs that otherwise would erroneously be classified as IgE epitopes. In validation studies we were able to retrieve artificial test-peptide beads spiked into our library by using IgE directed against those test-peptides at physiological concentrations (≤20 IU/ml of specific IgE), and disease-relevant bead-bound epitopes of the major peanut allergen Ara h 2 by screening with sera from peanut allergics. Thus, we established a platform with which one can find and validate new immunoglobulin targets using patient material which displays a largely unknown immunoglobulin repertoire.
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Affiliation(s)
- Thorsten Krause
- Division of Mucosal Immunology and Diagnostics, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany.,Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany
| | - Niels Röckendorf
- Division of Mucosal Immunology and Diagnostics, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany.,Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany
| | - Barbara Meckelein
- Division of Mucosal Immunology and Diagnostics, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany.,Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany
| | - Heike Sinnecker
- Division of Mucosal Immunology and Diagnostics, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany.,Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany
| | - Christian Schwager
- Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany.,Division of Clinical Molecular Allergology, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany
| | - Stefanie Möckel
- Flow Cytometry Core Facility, Institute of Molecular Biology, Mainz, Germany
| | - Uta Jappe
- Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany.,Division of Clinical Molecular Allergology, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany.,Interdisciplinary Allergy Outpatient Clinic, Department of Pneumology, University of Lübeck, Lübeck, Germany
| | - Andreas Frey
- Division of Mucosal Immunology and Diagnostics, Priority Area Asthma and Allergy, Research Center Borstel, Borstel, Germany.,Airway Research Center North, German Center for Lung Research (DZL), Borstel, Germany
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5
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Li G, Henry SA, Liu H, Kang TS, Nao SC, Zhao Y, Wu C, Jin J, Zhang JT, Leung CH, Wai Hong Chan P, Ma DL. A robust photoluminescence screening assay identifies uracil-DNA glycosylase inhibitors against prostate cancer. Chem Sci 2020; 11:1750-1760. [PMID: 34123270 PMCID: PMC8148385 DOI: 10.1039/c9sc05623h] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Many cancers have developed resistance to 5-FU, due to removal by the enzyme uracil-DNA glycosylase (UDG), a type of base excision repair enzyme (BER) that can excise uracil and 5-fluorouracil (5-FU) from DNA. However, the development of UDG inhibitor screening methods, especially for the rapid and efficient screening of natural product/natural product-like compounds, is still limited so far. We developed herein a robust time-resolved photoluminescence method for screening UDG inhibitors, which could significantly improve sensitivity over the screening method based on the conventional steady-state spectroscopy, reducing the substantial fluorescence background interference. As a proof-of-concept, two potential UDG inhibitors were identified from a database of natural products and approved drugs. Co-treatment of these two compounds with 5-FU showed synergistic cytotoxicity, providing the basis for treating drug-resistant cancers. Overall, this method provides an avenue for the rapid screening of small molecule regulators of other BER enzyme activities that can avoid false negatives arising from the background fluorescence. The discovery of UDG inhibitors against prostate cancer by using a robust photoluminescence screening assay that can avoid false negatives arising from the background fluorescence.![]()
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Affiliation(s)
- Guodong Li
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau Macau
| | | | - Hao Liu
- Department of Chemistry, Hong Kong Baptist University Kowloon Tong Hong Kong
| | - Tian-Shu Kang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau Macau
| | - Sang-Cuo Nao
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau Macau
| | - Yichao Zhao
- School of Chemistry, Monash University Clayton Victoria 3800 Australia
| | - Chun Wu
- Department of Chemistry, Hong Kong Baptist University Kowloon Tong Hong Kong
| | - Jianwen Jin
- School of Chemistry, Monash University Clayton Victoria 3800 Australia
| | - Jia-Tong Zhang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau Macau
| | - Chung-Hang Leung
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau Macau
| | - Philip Wai Hong Chan
- Department of Chemistry, University of Warwick Coventry CV4 7AL UK.,School of Chemistry, Monash University Clayton Victoria 3800 Australia
| | - Dik-Lung Ma
- Department of Chemistry, Hong Kong Baptist University Kowloon Tong Hong Kong
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6
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Multiplexed Competitive Screening of One-Bead-One-Component Combinatorial Libraries Using a ClonePix 2 Colony Sorter. Int J Mol Sci 2019; 20:ijms20205119. [PMID: 31623061 PMCID: PMC6830312 DOI: 10.3390/ijms20205119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/12/2019] [Accepted: 10/13/2019] [Indexed: 12/24/2022] Open
Abstract
Screening solid-phase combinatorial libraries of bioactive compounds against fluorescently labeled target biomolecules is an established technology in ligand and drug discovery. Rarely, however, do screening methods include comprehensive strategies-beyond mere library blocking and competitive screening-to ensure binding selectivity of selected leads. This work presents a method for multiplexed solid-phase peptide library screening using a ClonePix 2 Colony Picker that integrates (i) orthogonal fluorescent labeling for positive selection against a target protein and negative selection against competitor species with (ii) semi-quantitative tracking of target vs. competitor binding for every library bead. The ClonePix 2 technology enables global at-a-glance evaluation and customization of the parameters for bead selection to ensure high affinity and selectivity of the isolated leads. A case study is presented by screening a peptide library against green-labeled human immunoglobulin G (IgG) and red-labeled host cell proteins (HCPs) using ClonePix 2 to select HCP-binding ligands for flow-through chromatography applications. Using this approach, 79 peptide ligand candidates (6.6% of the total number of ligands screened) were identified as potential HCP-selective ligands, enabling a potential rate of >3,000 library beads screened per hour.
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7
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Maresh ME, Trader DJ. Development of a Method To Prioritize Protein-Ligand Pairs on Beads Using Protein Conjugated to a Near-IR Dye. ACS COMBINATORIAL SCIENCE 2019; 21:223-228. [PMID: 30677288 DOI: 10.1021/acscombsci.8b00165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The development of techniques to screen one-bead-one-compound (OBOC) libraries remains a critical step in identifying small molecules that bind target proteins. While great strides have been made, there remains a need to continue to develop OBOC screening techniques that not only reliably identify hit molecules but also can distinguish poor from excellent binders in a single screen. Similarly, relatively strong binding between a small molecule and protein target is required to be considered a hit from the initial pool of screened molecules. Here, we present the framework for a method to screen OBOC libraries using proteins and antibodies stained with a near-infrared (NIR)-emitting fluorophore. These labeled proteins provide significant signal at very low concentrations because of their fluorescence quantum yield. This work revealed that we can detect proteins and antibodies interacting with a known binding partner at low nanomolar concentrations; binding is specific, and known binders to carbonic anhydrase can be detected and ranked.
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Affiliation(s)
- Marianne E. Maresh
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 West Stadium Avenue, West Lafayette, Indiana 47907, United States
| | - Darci J. Trader
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 West Stadium Avenue, West Lafayette, Indiana 47907, United States
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8
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Qi L, Knapton EK, Zhang X, Zhang T, Gu C, Zhao Y. Pre-culture Sudan Black B treatment suppresses autofluorescence signals emitted from polymer tissue scaffolds. Sci Rep 2017; 7:8361. [PMID: 28827657 PMCID: PMC5567053 DOI: 10.1038/s41598-017-08723-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 07/17/2017] [Indexed: 01/21/2023] Open
Abstract
In tissue engineering, autofluorescence of polymer scaffolds often lowers the image contrast, making it difficult to examine cells and subcellular structures. Treating the scaffold materials with Sudan Black B (SBB) after cell fixation can effectively suppress autofluorescence, but this approach is not conducive to live cell imaging. Post-culture SBB treatment also disrupts intracellular structures and leads to reduced fluorescence intensity of the targets of interest. In this study, we introduce pre-culture SBB treatment to suppress autofluorescence, where SBB is applied to polymeric scaffold materials before cell seeding. The results show that the autofluorescence signals emitted from polycaprolactone (PCL) scaffolds in three commonly used fluorescence channels effectively decrease without diminishing the fluorescence signals emitted from the cells. The pre-culture SBB treatment does not significantly affect cell viability. The autofluorescence suppressive effect does not substantially diminish during the culturing period up to 28 days. The results also show that cell migration, proliferation, and myogenic differentiation in pre-culture SBB-treated groups do not exhibit statistical difference from the non-treated groups. As such, this approach greatly improves the fluorescence image quality for examining live cell behaviors and dynamics while the cells are cultured within autofluorescent polymer scaffolds.
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Affiliation(s)
- Lin Qi
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Erin K Knapton
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Xu Zhang
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Tongwen Zhang
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Chen Gu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Yi Zhao
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, 43210, USA.
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9
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Vastl J, Wang T, Trinh TB, Spiegel DA. Encoded Silicon-Chip-Based Platform for Combinatorial Synthesis and Screening. ACS COMBINATORIAL SCIENCE 2017; 19:255-261. [PMID: 28263558 DOI: 10.1021/acscombsci.6b00181] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Solid-supported chemical libraries have proven useful for the rapid and cost-effective discovery of bioactive compounds. However, traditional on-bead screening involves time-intensive chemical characterization of hit compounds and high false positive rates. Herein, we report a new platform for encoded chemical synthesis and solid-supported screening using p-Chips, microsized silicon microtransponders capable of storing and emitting unique numerical identifiers (IDs). By encoding the structures of library members using p-Chip IDs, we can track compound identities throughout both split-and-pool synthesis and protein binding assays without destructive cleavage. Thanks to the numerical IDs, our p-Chip platform can provide binding constants for library members simply by stripping and reprobing with different protein concentrations, unlike traditional on-bead assays. To showcase these features, we synthesized a library of 108 hemagglutinin (HA) peptide variants using split-and-pool approach, and measured EC50s for each variant directly on p-Chips. On-chip EC50s obtained from these studies showed excellent correlation (80%) with those obtained using traditional ELISA methods. Our screen also yielded a false positive rate of 14%, markedly superior to that reported for conventional bead-based binding studies (66-96%).1-9 On the basis of these results, we believe the p-Chip platform has the potential to improve the effectiveness of solid-supported high-throughput screening by a significant margin.
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Affiliation(s)
- Julian Vastl
- Department of Chemistry, Yale University, 225
Prospect Street, New Haven, Connecticut 06511, United States
| | - Tina Wang
- Department of Chemistry, Yale University, 225
Prospect Street, New Haven, Connecticut 06511, United States
| | - Thi B. Trinh
- Department of Chemistry, Yale University, 225
Prospect Street, New Haven, Connecticut 06511, United States
| | - David A. Spiegel
- Department of Chemistry, Yale University, 225
Prospect Street, New Haven, Connecticut 06511, United States
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10
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Allan CM, Larsson M, Jung RS, Ploug M, Bensadoun A, Beigneux AP, Fong LG, Young SG. Mobility of "HSPG-bound" LPL explains how LPL is able to reach GPIHBP1 on capillaries. J Lipid Res 2016; 58:216-225. [PMID: 27811232 DOI: 10.1194/jlr.m072520] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 10/31/2016] [Indexed: 12/22/2022] Open
Abstract
In mice lacking glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1), the LPL secreted by adipocytes and myocytes remains bound to heparan sulfate proteoglycans (HSPGs) on all cells within tissues. That observation raises a perplexing issue: Why isn't the freshly secreted LPL in wild-type mice captured by the same HSPGs, thereby preventing LPL from reaching GPIHBP1 on capillaries? We hypothesized that LPL-HSPG interactions are transient, allowing the LPL to detach and move to GPIHBP1 on capillaries. Indeed, we found that LPL detaches from HSPGs on cultured cells and moves to: 1) soluble GPIHBP1 in the cell culture medium; 2) GPIHBP1-coated agarose beads; and 3) nearby GPIHBP1-expressing cells. Movement of HSPG-bound LPL to GPIHBP1 did not occur when GPIHBP1 contained a Ly6 domain missense mutation (W109S), but was almost normal when GPIHBP1's acidic domain was mutated. To test the mobility of HSPG-bound LPL in vivo, we injected GPIHBP1-coated agarose beads into the brown adipose tissue of GPIHBP1-deficient mice. LPL moved quickly from HSPGs on adipocytes to GPIHBP1-coated beads, thereby depleting LPL stores on the surface of adipocytes. We conclude that HSPG-bound LPL in the interstitial spaces of tissues is mobile, allowing the LPL to move to GPIHBP1 on endothelial cells.
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Affiliation(s)
- Christopher M Allan
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Mikael Larsson
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Rachel S Jung
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, DK-2200 Copenhagen N, Denmark and Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK-220 Copenhagen N, Denmark
| | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY 14853
| | - Anne P Beigneux
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Loren G Fong
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Stephen G Young
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095 .,Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
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11
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Heusermann W, Ludin B, Pham NT, Auer M, Weidemann T, Hintersteiner M. A Wide-Field Fluorescence Microscope Extension for Ultrafast Screening of One-Bead One-Compound Libraries Using a Spectral Image Subtraction Approach. ACS COMBINATORIAL SCIENCE 2016; 18:209-19. [PMID: 27057765 DOI: 10.1021/acscombsci.5b00175] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The increasing involvement of academic institutions and biotech companies in drug discovery calls for cost-effective methods to identify new bioactive molecules. Affinity-based on-bead screening of combinatorial one-bead one-compound libraries combines a split-mix synthesis design with a simple protein binding assay operating directly at the bead matrix. However, one bottleneck for academic scale on-bead screening is the unavailability of a cheap, automated, and robust screening platform that still provides a quantitative signal related to the amount of target protein binding to individual beads for hit bead ranking. Wide-field fluorescence microscopy has long been considered unsuitable due to significant broad spectrum autofluorescence of the library beads in conjunction with low detection sensitivity. Herein, we demonstrate how such a standard microscope equipped with LED-based excitation and a modern CMOS camera can be successfully used for selecting hit beads. We show that the autofluorescence issue can be overcome by an optical image subtraction approach that yields excellent signal-to-noise ratios for the detection of bead-associated target proteins. A polymer capillary attached to a semiautomated bead-picking device allows the operator to efficiently isolate individual hit beads in less than 20 s. The system can be used for ultrafast screening of >200,000 bead-bound compounds in 1.5 h, thereby making high-throughput screening accessible to a wider group within the scientific community.
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Affiliation(s)
- Wolf Heusermann
- IMCF
Biozentrum, Universität Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Beat Ludin
- Life Imaging Services, Efringerstrasse
79, 4057 Basel, Switzerland
| | - Nhan T Pham
- School
of Biological Sciences and School of Biomedical Sciences, University of Edinburgh, CH Waddington Building, Max Born Crescent, The King's
Buildings, Edinburgh, EH9
3BF, United Kingdom
| | - Manfred Auer
- School
of Biological Sciences and School of Biomedical Sciences, University of Edinburgh, CH Waddington Building, Max Born Crescent, The King's
Buildings, Edinburgh, EH9
3BF, United Kingdom
| | - Thomas Weidemann
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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