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Lozoya-Colinas A, Yu Y, Chaput JC. Functionally Enhanced XNA Aptamers Discovered by Parallelized Library Screening. J Am Chem Soc 2023; 145:25789-25796. [PMID: 37962593 PMCID: PMC10690791 DOI: 10.1021/jacs.3c09497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023]
Abstract
In vitro evolution strategies have been used for >30 years to generate nucleic acid aptamers against therapeutic targets of interest, including disease-associated proteins. However, this process requires many iterative cycles of selection and amplification, which severely restricts the number of target and library design combinations that can be explored in parallel. Here, we describe a single-round screening approach to aptamer discovery that relies on function-enhancing chemotypes to increase the distribution of high-affinity sequences in a random-sequence library. We demonstrate the success of de novo discovery by affinity selection of threomers against the receptor binding domain of the S1 protein from SARS-CoV-2. Detailed biochemical characterization of the enriched population identified threomers with binding affinity values that are comparable to aptamers produced by conventional SELEX. This work establishes a highly parallelizable path for querying diverse chemical repertoires and may offer a viable route for accelerating the discovery of therapeutic aptamers.
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Affiliation(s)
- Adriana Lozoya-Colinas
- Department
of Pharmaceutical Sciences, University of
California, Irvine, Irvine, California 92697-3958, United States
| | - Yutong Yu
- Department
of Pharmaceutical Sciences, University of
California, Irvine, Irvine, California 92697-3958, United States
| | - John C. Chaput
- Department
of Pharmaceutical Sciences, University of
California, Irvine, Irvine, California 92697-3958, United States
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697-3958, United States
- Department
of Molecular Biology and Biochemistry, University
of California, Irvine, Irvine, California 92697-3958, United States
- Department
of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-3958, United States
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2
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Zhao L, Wang Q, Yin Y, Yang Y, Cui H, Dong Y. Evolution of Interferon-Gamma Aptamer with Good Affinity and Analytical Utility by a Rational In Silico Base Mutagenesis Post-SELEX Strategy. Molecules 2022; 27:molecules27175725. [PMID: 36080490 PMCID: PMC9457990 DOI: 10.3390/molecules27175725] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/24/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
The Systematic Evolution of Ligands by EXponential enrichment (SELEX) is conventionally an effective method to identify aptamers, which are oligonucleotide sequences with desired properties to recognize targets specifically and sensitively. However, there are some inherent limitations, e.g., the loss of potential high-affinity sequences during biased iterative PCR enrichment processes and the limited structural diversity of the initial library, which seriously restrict their real-world applications. To overcome these limitations, the in silico base mutagenesis post-SELEX strategy based on the low Gibbs free energy (ΔG) and genetic algorithm was developed for the optimization of the interferon-gamma aptamer (B1-4). In the process of evolution, new sequences were created and the aptamer candidates with low ΔG values and advanced structures were produced. After five rounds of selection, systematic studies revealed that the affinity of the newly developed evolutionary aptamer (M5-5) was roughly 10-fold higher than that of the parent aptamer (B1-4), and an aptasensor detection system with a limit-of-detection (LOD) value of 3.17 nM was established based on the evolutionary aptamer. The proposed approach provided an efficient strategy to improve the aptamer with low energy and a high binding ability, and the good analytical utility thereof.
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Affiliation(s)
- Lianhui Zhao
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Qionglin Wang
- Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Zhengzhou 450018, China
| | - Yingai Yin
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yan Yang
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Huifang Cui
- College of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Yiyang Dong
- College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
- Correspondence: ; Tel.: +86-010-64446260
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3
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Zhu C, Li L, Yang G, Qu F. Investigating the Influences of Random-Region Length on Aptamer Selection Efficiency Based on Capillary Electrophoresis-SELEX and High-Throughput Sequencing. Anal Chem 2021; 93:17030-17035. [PMID: 34908408 DOI: 10.1021/acs.analchem.1c03661] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
For aptamer selection, the random-region length of an ssDNA library was generally taken in a relatively arbitrary fashion, which may lead to failure for unsuitable target binding. Herein, we coupled high-efficiency capillary electrophoresis (CE)-SELEX and high-throughput sequencing (HTS) to investigate the influences of random-region length. First, one round of selection against programmed cell death-ligand 1 (PD-L1) was performed using ssDNA libraries with random-region lengths of 15, 30, 40, and 60 nt, respectively. A good correlation was observed between candidates' random-region lengths and dissociation constant (Kd), in which the longer sequences presented higher affinity, and the picked Seq 60-1 after one round notably presented a similar affinity toward a reported aptamer through eight rounds. Molecular dynamics (MD) simulation suggested, for PD-L1, the long sequence could supply more noncovalent bonds including hydrogen bonds, electrostatic interactions, and hydrophobic interactions to form a stable protein/aptamer complex. Besides, four other proteins with selective binding performances validated the importance of random-region length. To further investigate how random-region length affects the selection efficiency, a mixed library with random-region lengths ranging from 10 to 50 nt was employed for six rounds of selection against Piezo2. Sequence variations were tracked by HTS, showing the preferential evolution and PCR uncertainty with even higher impact were the main causes. This study suggested random-region length plays a crucial factor, and a mixed library with different random-region sequences can be a worthy choice for increasing the speed of high-affinity aptamer selection. Moreover, the PCR process should be given particular attention in aptamer selection.
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Affiliation(s)
- Chao Zhu
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing 100081, China.,Institute of Quality Standard and Testing Technology for Agro-products, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Linsen Li
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Ge Yang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
| | - Feng Qu
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing 100081, China
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4
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Costello AM, Elizondo-Riojas MA, Li X, Volk DE, Pillai AK, Wang H. Selection and Characterization of Vimentin-Binding Aptamer Motifs for Ovarian Cancer. Molecules 2021; 26:6525. [PMID: 34770931 DOI: 10.3390/molecules26216525] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/20/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022] Open
Abstract
The application of aptamers in biomedicine is emerging as an essential technology in the field of cancer research. As small single-stranded DNA or RNA ligands with high specificity and low immunogenicity for their targets, aptamers provide many advantages in cancer therapeutics over protein-based molecules, such as antibodies. Vimentin is an intermediate filament protein that is overexpressed in endothelial cells of cancerous tissue. High expression levels of vimentin have been associated with increased capacity for migration and invasion of the tumor cells. We have selected and identified thioated aptamers with high specificity for vimentin using human ovarian cancer tissues. Tentative binding motifs were chosen for two vimentin aptamers based on predicted secondary structures. Each of these shorter, tentative binding motifs was synthesized, purified, and characterized via cell binding assays. Two vimentin binding motifs with high fidelity binding were selected and further characterized via cell and tissue binding assays, as well as flow cytometric analysis. The equilibrium binding constants of these small thioated aptamer constructs were also determined. Future applications for the vimentin binding aptamer motifs include conjugation of the aptamers to synthetic dyes for use in targeted imaging and therapy, and ultimately more detailed and precise monitoring of treatment response and tumor progression in ovarian pathology.
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5
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Abstract
The Competition-Enhanced Ligand Selection (CompELS) approach was used to identify aptamer candidates for spherical gold nanoparticles (AuNPs). This approach differs from conventional Systematic Evolution of Ligands by EXponential enrichment (SELEX)-based aptamer screening by eliminating repeated elution and polymerase chain reaction (PCR) amplification steps of bound candidate sequences between each selection round to continually enrich the candidate aptamer pool with oligonucleotides remaining from an earlier SELEX selection round. Instead, a new pool of unenriched oligonucleotides is added during each CompELS selection round to compete with existing target-bound oligonucleotides species for target binding sites. In this study, 24 aptamer candidates for AuNPs were identified using the CompELS approach and then compared to reveal similarities in their primary structures and their predicted secondary structures. No strong patterns in individual base identities (position-dependent) nor in segments of consecutive bases (independent of position) prevailed among the identified sequences. Motifs in predicted secondary structures, on the other hand, were shared among otherwise unrelated aptamer sequences. These motifs were revealed using a systematic classification and enumeration of distinct secondary structure elements, namely, hairpins, duplexes, single-stranded segments, interior loops, bulges, and multibranched loops.
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Affiliation(s)
| | - Patrick Dennis
- Materials & Manufacturing Directorate, Soft Matter Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
| | - Rajesh R Naik
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
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6
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Yasmeen F, Seo H, Javaid N, Kim MS, Choi S. Therapeutic Interventions into Innate Immune Diseases by Means of Aptamers. Pharmaceutics 2020; 12:pharmaceutics12100955. [PMID: 33050544 PMCID: PMC7600108 DOI: 10.3390/pharmaceutics12100955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/03/2020] [Accepted: 10/04/2020] [Indexed: 12/25/2022] Open
Abstract
The immune system plays a crucial role in the body's defense system against various pathogens, such as bacteria, viruses, and parasites, as well as recognizes non-self- and self-molecules. The innate immune system is composed of special receptors known as pattern recognition receptors, which play a crucial role in the identification of pathogen-associated molecular patterns from diverse microorganisms. Any disequilibrium in the activation of a particular pattern recognition receptor leads to various inflammatory, autoimmune, or immunodeficiency diseases. Aptamers are short single-stranded deoxyribonucleic acid or ribonucleic acid molecules, also termed "chemical antibodies," which have tremendous specificity and affinity for their target molecules. Their features, such as stability, low immunogenicity, ease of manufacturing, and facile screening against a target, make them preferable as therapeutics. Immune-system-targeting aptamers have a great potential as a targeted therapeutic strategy against immune diseases. This review summarizes components of the innate immune system, aptamer production, pharmacokinetic characteristics of aptamers, and aptamers related to innate-immune-system diseases.
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7
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Ishida R, Adachi T, Yokota A, Yoshihara H, Aoki K, Nakamura Y, Hamada M. RaptRanker: in silico RNA aptamer selection from HT-SELEX experiment based on local sequence and structure information. Nucleic Acids Res 2020; 48:e82. [PMID: 32537639 PMCID: PMC7641312 DOI: 10.1093/nar/gkaa484] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 01/02/2023] Open
Abstract
Aptamers are short single-stranded RNA/DNA molecules that bind to specific target molecules. Aptamers with high binding-affinity and target specificity are identified using an in vitro procedure called high throughput systematic evolution of ligands by exponential enrichment (HT-SELEX). However, the development of aptamer affinity reagents takes a considerable amount of time and is costly because HT-SELEX produces a large dataset of candidate sequences, some of which have insufficient binding-affinity. Here, we present RNA aptamer Ranker (RaptRanker), a novel in silico method for identifying high binding-affinity aptamers from HT-SELEX data by scoring and ranking. RaptRanker analyzes HT-SELEX data by evaluating the nucleotide sequence and secondary structure simultaneously, and by ranking according to scores reflecting local structure and sequence frequencies. To evaluate the performance of RaptRanker, we performed two new HT-SELEX experiments, and evaluated binding affinities of a part of sequences that include aptamers with low binding-affinity. In both datasets, the performance of RaptRanker was superior to Frequency, Enrichment and MPBind. We also confirmed that the consideration of secondary structures is effective in HT-SELEX data analysis, and that RaptRanker successfully predicted the essential subsequence motifs in each identified sequence.
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Affiliation(s)
- Ryoga Ishida
- Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | | | - Aya Yokota
- Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | | | | | | | - Michiaki Hamada
- Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.,Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan
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8
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Dasti A, Cid-samper F, Bechara E, Tartaglia GG. RNA-centric approaches to study RNA-protein interactions in vitro and in silico. Methods 2020; 178:11-8. [DOI: 10.1016/j.ymeth.2019.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 09/10/2019] [Accepted: 09/10/2019] [Indexed: 01/17/2023] Open
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9
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Naseri M, Mohammadniaei M, Sun Y, Ashley J. The Use of Aptamers and Molecularly Imprinted Polymers in Biosensors for Environmental Monitoring: A Tale of Two Receptors. Chemosensors 2020; 8:32. [DOI: 10.3390/chemosensors8020032] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Effective molecular recognition remains a major challenge in the development of robust receptors for biosensing applications. Over the last three decades, aptamers and molecularly imprinted polymers (MIPs) have emerged as the receptors of choice for use in biosensors as viable alternatives to natural antibodies, due to their superior stability, comparable binding performance, and lower costs. Although both of these technologies have been developed in parallel, they both suffer from their own unique problems. In this review, we will compare and contrast both types of receptor, with a focus on the area of environmental monitoring. Firstly, we will discuss the strategies and challenges involved in their development. We will also discuss the challenges that are involved in interfacing them with the biosensors. We will then compare and contrast their performance with a focus on their use in the detection of environmental contaminants, namely, antibiotics, pesticides, heavy metals, and pathogens detection. Finally, we will discuss the future direction of these two technologies.
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10
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Davydova AS, Krasheninina OA, Tupikin AE, Kabilov MR, Venyaminova AG, Vorobyeva MA. Synthesis of Random DNA Libraries for In Vitro Selection and Analysis of Their Nucleotide Composition. Russ J Bioorg Chem 2020. [DOI: 10.1134/s1068162019060141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Adachi T, Nakamura Y. Aptamers: A Review of Their Chemical Properties and Modifications for Therapeutic Application. Molecules 2019; 24:E4229. [PMID: 31766318 DOI: 10.3390/molecules24234229] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 11/20/2019] [Indexed: 12/29/2022] Open
Abstract
Aptamers are short, single-stranded oligonucleotides that bind to specific target molecules. The shape-forming feature of single-stranded oligonucleotides provides high affinity and excellent specificity toward targets. Hence, aptamers can be used as analogs of antibodies. In December 2004, the US Food and Drug Administration approved the first aptamer-based therapeutic, pegaptanib (Macugen), targeting vascular endothelial growth factor, for the treatment of age-related macular degeneration. Since then, however, no aptamer medication for public health has appeared. During these relatively silent years, many trials and improvements of aptamer therapeutics have been performed, opening multiple novel directions for the therapeutic application of aptamers. This review summarizes the basic characteristics of aptamers and the chemical modifications available for aptamer therapeutics.
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12
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Abstract
Aptamers are small oligonucleotides that are capable of binding specifically to a target, with impressive potential for analysis, diagnostics, and therapeutics applications. Aptamers are isolated from large nucleic acid combinatorial libraries using an iterative selection process called SELEX (Systematic Evolution of Ligands by EXponential enrichment). Since being implemented 30 years ago, the SELEX protocol has undergone many modifications and improvements, but it remains a laborious, time-consuming, and costly method, and the results are not always successful. Each step in the aptamer selection protocol can influence its results. This review discusses key technical points of the SELEX procedure and their influence on the outcome of aptamer selection.
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Affiliation(s)
- Natalia Komarova
- Scientific-Manufacturing Complex Technological Centre, 1-7 Shokin Square, Zelenograd, Moscow 124498, Russia.
| | - Alexander Kuznetsov
- Scientific-Manufacturing Complex Technological Centre, 1-7 Shokin Square, Zelenograd, Moscow 124498, Russia.
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13
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Yan J, Xiong H, Cai S, Wen N, He Q, Liu Y, Peng D, Liu Z. Advances in aptamer screening technologies. Talanta 2019; 200:124-144. [DOI: 10.1016/j.talanta.2019.03.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 02/20/2019] [Accepted: 03/02/2019] [Indexed: 02/07/2023]
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14
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He B, Chen H, Li N, Huang J. SAROTUP: a suite of tools for finding potential target-unrelated peptides from phage display data. Int J Biol Sci 2019; 15:1452-1459. [PMID: 31337975 PMCID: PMC6643146 DOI: 10.7150/ijbs.31957] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 04/09/2019] [Indexed: 01/13/2023] Open
Abstract
SAROTUP (Scanner And Reporter Of Target-Unrelated Peptides) 3.1 is a significant upgrade to the widely used SAROTUP web server for the rapid identification of target-unrelated peptides (TUPs) in phage display data. At present, SAROTUP has gathered a suite of tools for finding potential TUPs and other purposes. Besides the TUPScan, the motif-based tool, and three tools based on the BDB database, i.e., MimoScan, MimoSearch, and MimoBlast, three predictors based on support vector machine, i.e., PhD7Faster, SABinder and PSBinder, are integrated into SAROTUP. The current version of SAROTUP contains 27 TUP motifs and 823 TUP sequences. We also developed the standalone SAROTUP application with graphical user interface (GUI) and command line versions for processing deep sequencing phage display data and distributed it as an open source package, which can perform perfectly locally on almost all systems that support C++ with little or no modification. The web interfaces of SAROTUP have also been redesigned to be more self-evident and user-friendly. The latest version of SAROTUP is freely available at http://i.uestc.edu.cn/sarotup3.
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Affiliation(s)
- Bifang He
- School of Medicine, Guizhou University, Guiyang 550025, China.,Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Heng Chen
- School of Medicine, Guizhou University, Guiyang 550025, China
| | - Ning Li
- Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Jian Huang
- Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 611731, China
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15
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Kushwaha A, Takamura Y, Nishigaki K, Biyani M. Competitive non-SELEX for the selective and rapid enrichment of DNA aptamers and its use in electrochemical aptasensor. Sci Rep 2019; 9:6642. [PMID: 31040350 PMCID: PMC6491428 DOI: 10.1038/s41598-019-43187-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 04/17/2019] [Indexed: 02/07/2023] Open
Abstract
The SELEX (Systematic Evolution of Ligands by EXponential enrichment) method has been used successfully since 1990, but work is still required to obtain highly specific aptamers. Here, we present a novel approach called ‘Competitive non-SELEX’ (and termed as ‘SELCOS’ (Systematic Evolution of Ligands by COmpetitive Selection)) for readily obtaining aptamers that can discriminate between highly similar targets. This approach is based on the theoretical background presented here, in which under the co-presence of two similar targets, a specific binding type can be enriched more than a nonspecifically binding one during repetitive steps of partitioning with no PCR amplification between them. This principle was experimentally confirmed by the selection experiment for influenza virus subtype-specific DNA aptamers. Namely, the selection products (pools of DNA aptamers) obtained by SELCOS were subjected to a DEPSOR-mode electrochemical sensor, enabling the method to select subtype-specific aptamer pools. From the clonal analysis of these pools, only a few rounds of in vitro selection were sufficient to achieve the surprisingly rapid enrichment of a small number of aptamers with high selectivity, which could be attributed to the SELCOS principle and the given selection pressure program. The subtype-specific aptamers obtained in this manner had a high affinity (e.g., KD = 82 pM for H1N1; 88 pM for H3N2) and negligible cross-reactivity. By making the H1N1-specific DNA aptamer a sensor unit of the DEPSOR electrochemical detector, an influenza virus subtype-specific and portable detector was readily constructed, indicating how close it is to the field application goal.
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Affiliation(s)
- Ankita Kushwaha
- Department of Bioscience and Biotechnology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa, 923-1292, Japan
| | - Yuzuru Takamura
- Department of Bioscience and Biotechnology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa, 923-1292, Japan
| | - Koichi Nishigaki
- Department of Bioscience and Biotechnology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa, 923-1292, Japan.,BioSeeds Corporation, JAIST venture business laboraotry, 1-1 Asahidai, Nomi City, Ishikawa, 923-1292, Japan
| | - Manish Biyani
- Department of Bioscience and Biotechnology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa, 923-1292, Japan. .,BioSeeds Corporation, JAIST venture business laboraotry, 1-1 Asahidai, Nomi City, Ishikawa, 923-1292, Japan.
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16
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Orlandini von Niessen AG, Poleganov MA, Rechner C, Plaschke A, Kranz LM, Fesser S, Diken M, Löwer M, Vallazza B, Beissert T, Bukur V, Kuhn AN, Türeci Ö, Sahin U. Improving mRNA-Based Therapeutic Gene Delivery by Expression-Augmenting 3' UTRs Identified by Cellular Library Screening. Mol Ther 2019; 27:824-36. [PMID: 30638957 DOI: 10.1016/j.ymthe.2018.12.011] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 01/14/2023] Open
Abstract
Synthetic mRNA has emerged as a powerful tool for the transfer of genetic information, and it is being explored for a variety of therapeutic applications. Many of these applications require prolonged intracellular persistence of mRNA to improve bioavailability of the encoded protein. mRNA molecules are intrinsically unstable and their intracellular kinetics depend on the UTRs embracing the coding sequence, in particular the 3' UTR elements. We describe here a novel and generally applicable cell-based selection process for the identification of 3' UTRs that augment the expression of proteins encoded by synthetic mRNA. Moreover, we show, for two applications of mRNA therapeutics, namely, (1) the delivery of vaccine antigens in order to mount T cell immune responses and (2) the introduction of reprogramming factors into differentiated cells in order to induce pluripotency, that mRNAs tagged with the 3' UTR elements discovered in this study outperform those with commonly used 3' UTRs. This approach further leverages the utility of mRNA as a gene therapy drug format.
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17
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Wang T, Chen C, Larcher LM, Barrero RA, Veedu RN. Three decades of nucleic acid aptamer technologies: Lessons learned, progress and opportunities on aptamer development. Biotechnol Adv 2018; 37:28-50. [PMID: 30408510 DOI: 10.1016/j.biotechadv.2018.11.001] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/28/2018] [Accepted: 11/04/2018] [Indexed: 02/07/2023]
Abstract
Aptamers are short single-stranded nucleic acid sequences capable of binding to target molecules in a way similar to antibodies. Due to various advantages such as prolonged shelf life, low batch to batch variation, low/no immunogenicity, freedom to incorporate chemical modification for enhanced stability and targeting capacity, aptamers quickly found their potential in diverse applications ranging from therapy, drug delivery, diagnosis, and functional genomics to bio-sensing. Aptamers are generated by a process called SELEX. However, the current overall success rate of SELEX is far from being satisfactory, and still presents a major obstacle for aptamer-based research and application. The need for an efficient selection strategy consisting of defined procedures to deal with a wide variety of targets is significantly important. In this work, by analyzing key aspects of SELEX including initial library design, target preparation, PCR optimization, and single strand DNA separation, we provide a comprehensive analysis of individual steps to facilitate researchers intending to develop personalized protocols to address many of the obstacles in SELEX. In addition, this review provides suggestions and opinions for future aptamer development procedures to address the concerns on key SELEX steps, and post-SELEX modifications.
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Affiliation(s)
- Tao Wang
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia; Perron Institute for Neurological and Translational Science, Perth 6009, Australia; School of Nursing, Zhengzhou University & Nursing Department, The First Affiliated Hospital of Zheng Zhou University, Zhengzhou 450001, China
| | - Changying Chen
- School of Nursing, Zhengzhou University & Nursing Department, The First Affiliated Hospital of Zheng Zhou University, Zhengzhou 450001, China
| | - Leon M Larcher
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia
| | - Roberto A Barrero
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia
| | - Rakesh N Veedu
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia; Perron Institute for Neurological and Translational Science, Perth 6009, Australia.
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18
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Abstract
Competition-enhanced ligand screening (CompELS) was employed to rapidly screen through large DNA libraries to identify single-stranded, oligonucleotide-based ligands called aptamers that bind to a nonbiological target. This previously unreported aptamer screening approach involves the repeated introduction of unenriched random sequence populations during the biopanning process, but avoids iterative elution and polymerase chain reaction (PCR) amplification steps inherent to traditional SELEX (systematic evolution of ligands by exponential enrichment) screening. In this study, 25 aptamers were identified against a gold surface via CompELS and evaluated to identify patterns in primary structures and predicted secondary structures. Following a final one-round competition experiment with the 25 identified aptamers, one particular aptamer sequence (1N) emerged as the most competitive adsorbate species for the gold substrate. Binding analysis indicated at least an order of magnitude difference in the binding affinity of 1N ( Kd = 5.6 × 10-10 M) compared to five other high affinity aptamer candidates ( Kd = 10-8-10-9 M) from identical secondary structure families. Collectively, these studies introduce a rapid, reliable screening and ranking platform along with a classification scheme well-suited for identifying and characterizing aptamers for nonbiological as well as biological targets.
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Affiliation(s)
| | - Joseph M. Slocik
- Materials & Manufacturing Directorate, Soft Matter Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
| | - Patrick B. Dennis
- Materials & Manufacturing Directorate, Soft Matter Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
| | - Rajesh R. Naik
- Materials & Manufacturing Directorate, Soft Matter Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
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19
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Pfeiffer F, Gröber C, Blank M, Händler K, Beyer M, Schultze JL, Mayer G. Systematic evaluation of error rates and causes in short samples in next-generation sequencing. Sci Rep 2018; 8:10950. [PMID: 30026539 PMCID: PMC6053417 DOI: 10.1038/s41598-018-29325-6] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 07/09/2018] [Indexed: 01/08/2023] Open
Abstract
Next-generation sequencing (NGS) is the method of choice when large numbers of sequences have to be obtained. While the technique is widely applied, varying error rates have been observed. We analysed millions of reads obtained after sequencing of one single sequence on an Illumina sequencer. According to our analysis, the index-PCR for sample preparation has no effect on the observed error rate, even though PCR is traditionally seen as one of the major contributors to enhanced error rates in NGS. In addition, we observed very persistent pre-phasing effects although the base calling software corrects for these. Removal of shortened sequences abolished these effects and allowed analysis of the actual mutations. The average error rate determined was 0.24 ± 0.06% per base and the percentage of mutated sequences was found to be 6.4 ± 1.24%. Constant regions at the 5'- and 3'-end, e.g., primer binding sites used in in vitro selection procedures seem to have no effect on mutation rates and re-sequencing of samples obtains very reproducible results. As phasing effects and other sequencing problems vary between equipment and individual setups, we recommend evaluation of error rates and types to all NGS-users to improve the quality and analysis of NGS data.
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Affiliation(s)
- Franziska Pfeiffer
- University of Bonn, LIMES Institute, Chemical Biology, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Carsten Gröber
- AptaIT GmbH, Am Klopferspitz 19A, 82152, Planegg, Germany
| | - Michael Blank
- AptaIT GmbH, Am Klopferspitz 19A, 82152, Planegg, Germany
| | - Kristian Händler
- University of Bonn, LIMES Institute, Genomics and Immunoregulation, Carl-Troll-Str. 31, 53115, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE) and University of Bonn, Platform for Single Cell Genomics and Epigenomics, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Marc Beyer
- University of Bonn, LIMES Institute, Genomics and Immunoregulation, Carl-Troll-Str. 31, 53115, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE) and University of Bonn, Platform for Single Cell Genomics and Epigenomics, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
- DZNE, Molecular Immunology in Neurodegeneration, Sigmund-Freud-Str. 27, 53127, Bonn, Germany
| | - Joachim L Schultze
- University of Bonn, LIMES Institute, Genomics and Immunoregulation, Carl-Troll-Str. 31, 53115, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE) and University of Bonn, Platform for Single Cell Genomics and Epigenomics, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Günter Mayer
- University of Bonn, LIMES Institute, Chemical Biology, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.
- Center of Aptamer Research and Development, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.
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20
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Abstract
Cell-derived nanosized vesicles or exosomes are expected to become delivery carriers for functional RNAs, such as small interfering RNA (siRNA). A method to efficiently load functional RNAs into exosomes is required for the development of exosome-based delivery carriers of functional RNAs. However, there is no method to find exosome-tropic exogenous RNA sequences. In this study, we used a systematic evolution of ligands by exponential enrichment (SELEX) method to screen exosome-tropic RNAs that can be used to load functional RNAs into exosomes by conjugation. Pooled single stranded 80-base RNAs, each of which contains a randomized 40-base sequence, were transfected into B16-BL6 murine melanoma cells and exosomes were collected from the cells. RNAs extracted from the exosomes were subjected to next round of SELEX. Cloning and sequencing of RNAs in SELEX-screened RNA pools showed that 29 of 56 clones had a typical RNA sequence. The sequence found by SELEX was enriched in exosomes after transfection to B16-BL6 cells. The results show that the SELEX-based method can be used for screening of exosome-tropic RNAs.
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Affiliation(s)
| | | | - Yuki Takahashi
- Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Kana Kato
- Graduate School of Pharmaceutical Sciences, Kyoto University
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21
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Domenyuk V, Gatalica Z, Santhanam R, Wei X, Stark A, Kennedy P, Toussaint B, Levenberg S, Wang J, Xiao N, Greil R, Rinnerthaler G, Gampenrieder SP, Heimberger AB, Berry DA, Barker A, Quackenbush J, Marshall JL, Poste G, Vacirca JL, Vidal GA, Schwartzberg LS, Halbert DD, Voss A, Magee D, Miglarese MR, Famulok M, Mayer G, Spetzler D. Poly-ligand profiling differentiates trastuzumab-treated breast cancer patients according to their outcomes. Nat Commun 2018; 9:1219. [PMID: 29572535 DOI: 10.1038/s41467-018-03631-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 03/01/2018] [Indexed: 12/22/2022] Open
Abstract
Assessing the phenotypic diversity underlying tumour progression requires the identification of variations in the respective molecular interaction networks. Here we report proof-of-concept for a platform called poly-ligand profiling (PLP) that surveys these system states and distinguishes breast cancer patients who did or did not derive benefit from trastuzumab. We perform tissue-SELEX on breast cancer specimens to enrich single-stranded DNA (ssDNA) libraries that preferentially interact with molecular components associated with the two clinical phenotypes. Testing of independent sample sets verifies the ability of PLP to classify trastuzumab-treated patients according to their clinical outcomes with ROC-AUC of 0.78. Standard HER2 testing of the same patients gives a ROC-AUC of 0.47. Kaplan–Meier analysis reveals a median increase in benefit from trastuzumab-containing treatments of 300 days for PLP-positive compared to PLP-negative patients. If prospectively validated, PLP may increase success rates in precision oncology and clinical trials, thus improving both patient care and drug development. Patients’ selection is particularly important in cancer treatment. Here the authors present a proof-of-principle methodology that could be potentially important in assisting therapeutic decisions in the treatment of breast cancer patients.
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22
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Vorobyeva MA, Davydova AS, Vorobjev PE, Pyshnyi DV, Venyaminova AG. Key Aspects of Nucleic Acid Library Design for in Vitro Selection. Int J Mol Sci 2018; 19:E470. [PMID: 29401748 PMCID: PMC5855692 DOI: 10.3390/ijms19020470] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 02/07/2023] Open
Abstract
Nucleic acid aptamers capable of selectively recognizing their target molecules have nowadays been established as powerful and tunable tools for biospecific applications, be it therapeutics, drug delivery systems or biosensors. It is now generally acknowledged that in vitro selection enables one to generate aptamers to almost any target of interest. However, the success of selection and the affinity of the resulting aptamers depend to a large extent on the nature and design of an initial random nucleic acid library. In this review, we summarize and discuss the most important features of the design of nucleic acid libraries for in vitro selection such as the nature of the library (DNA, RNA or modified nucleotides), the length of a randomized region and the presence of fixed sequences. We also compare and contrast different randomization strategies and consider computer methods of library design and some other aspects.
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Affiliation(s)
- Maria A. Vorobyeva
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
| | - Anna S. Davydova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
| | - Pavel E. Vorobjev
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
- Department of Natural Sciences, Novosibirsk State University, Pirogova St., 2, 630090 Novosibirsk, Russia
| | - Dmitrii V. Pyshnyi
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
- Department of Natural Sciences, Novosibirsk State University, Pirogova St., 2, 630090 Novosibirsk, Russia
| | - Alya G. Venyaminova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
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23
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He B, Tjhung KF, Bennett NJ, Chou Y, Rau A, Huang J, Derda R. Compositional Bias in Naïve and Chemically-modified Phage-Displayed Libraries uncovered by Paired-end Deep Sequencing. Sci Rep 2018; 8:1214. [PMID: 29352178 PMCID: PMC5775325 DOI: 10.1038/s41598-018-19439-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/02/2018] [Indexed: 01/09/2023] Open
Abstract
Understanding the composition of a genetically-encoded (GE) library is instrumental to the success of ligand discovery. In this manuscript, we investigate the bias in GE-libraries of linear, macrocyclic and chemically post-translationally modified (cPTM) tetrapeptides displayed on the M13KE platform, which are produced via trinucleotide cassette synthesis (19 codons) and NNK-randomized codon. Differential enrichment of synthetic DNA {S}, ligated vector {L} (extension and ligation of synthetic DNA into the vector), naïve libraries {N} (transformation of the ligated vector into the bacteria followed by expression of the library for 4.5 hours to yield a "naïve" library), and libraries chemically modified by aldehyde ligation and cysteine macrocyclization {M} characterized by paired-end deep sequencing, detected a significant drop in diversity in {L} → {N}, but only a minor compositional difference in {S} → {L} and {N} → {M}. Libraries expressed at the N-terminus of phage protein pIII censored positively charged amino acids Arg and Lys; libraries expressed between pIII domains N1 and N2 overcame Arg/Lys-censorship but introduced new bias towards Gly and Ser. Interrogation of biases arising from cPTM by aldehyde ligation and cysteine macrocyclization unveiled censorship of sequences with Ser/Phe. Analogous analysis can be used to explore library diversity in new display platforms and optimize cPTM of these libraries.
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Affiliation(s)
- Bifang He
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, AB T6G 2G2, Canada.,Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Katrina F Tjhung
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, AB T6G 2G2, Canada.,The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA, 92037, USA.,The Salk Institute, 10010 N. Torrey Pines Rd., La Jolla, CA, 92037, USA
| | - Nicholas J Bennett
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, AB T6G 2G2, Canada
| | - Ying Chou
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, AB T6G 2G2, Canada
| | - Andrea Rau
- GABI, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Jian Huang
- Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Center for Information in Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Ratmir Derda
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, AB T6G 2G2, Canada.
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24
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Catuogno S, Esposito CL. Aptamer Cell-Based Selection: Overview and Advances. Biomedicines 2017; 5:biomedicines5030049. [PMID: 28805744 PMCID: PMC5618307 DOI: 10.3390/biomedicines5030049] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 02/07/2023] Open
Abstract
Aptamers are high affinity single-stranded DNA/RNA molecules, produced by a combinatorial procedure named SELEX (Systematic Evolution of Ligands by Exponential enrichment), that are emerging as promising diagnostic and therapeutic tools. Among selection strategies, procedures using living cells as complex targets (referred as "cell-SELEX") have been developed as an effective mean to generate aptamers for heavily modified cell surface proteins, assuring the binding of the target in its native conformation. Here we give an up-to-date overview on cell-SELEX technology, discussing the most recent advances with a particular focus on cancer cell targeting. Examples of the different protocol applications and post-SELEX strategies will be briefly outlined.
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Affiliation(s)
- Silvia Catuogno
- Istituto di Endocrinologia ed Oncologia Sperimentale "G. Salvatore", CNR, Naples 80100, Italy.
| | - Carla Lucia Esposito
- Istituto di Endocrinologia ed Oncologia Sperimentale "G. Salvatore", CNR, Naples 80100, Italy.
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25
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Abstract
Nucleic acid aptamers, often termed 'chemical antibodies', are functionally comparable to traditional antibodies, but offer several advantages, including their relatively small physical size, flexible structure, quick chemical production, versatile chemical modification, high stability and lack of immunogenicity. In addition, many aptamers are internalized upon binding to cellular receptors, making them useful targeted delivery agents for small interfering RNAs (siRNAs), microRNAs and conventional drugs. However, several crucial factors have delayed the clinical translation of therapeutic aptamers, such as their inherent physicochemical characteristics and lack of safety data. This Review discusses these challenges, highlighting recent clinical developments and technological advances that have revived the impetus for this promising class of therapeutics.
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Affiliation(s)
- Jiehua Zhou
- Department of Molecular and Cellular Biology, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd, Duarte, CA 91010, USA
| | - John Rossi
- Department of Molecular and Cellular Biology, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd, Duarte, CA 91010, USA
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd, Duarte, CA 91010, USA
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26
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Stuart CH, Riley KR, Boyacioglu O, Herpai DM, Debinski W, Qasem S, Marini FC, Colyer CL, Gmeiner WH. Selection of a Novel Aptamer Against Vitronectin Using Capillary Electrophoresis and Next Generation Sequencing. Mol Ther Nucleic Acids 2016; 5:e386. [PMID: 27845768 DOI: 10.1038/mtna.2016.91] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/02/2016] [Indexed: 01/04/2023]
Abstract
Breast cancer (BC) results in ~40,000 deaths each year in the United States and even among survivors treatment of the disease may have devastating consequences, including increased risk for heart disease and cognitive impairment resulting from the toxic effects of chemotherapy. Aptamer-mediated drug delivery can contribute to improved treatment outcomes through the selective delivery of chemotherapy to BC cells, provided suitable cancer-specific antigens can be identified. We report here the use of capillary electrophoresis in conjunction with next generation sequencing to develop the first vitronectin (VN) binding aptamer (VBA-01; Kd 405 nmol/l, the first aptamer to vitronectin (VN; Kd = 405 nmol/l) , a protein that plays an important role in wound healing and that is present at elevated levels in BC tissue and in the blood of BC patients relative to the corresponding nonmalignant tissues. We used VBA-01 to develop DVBA-01, a dimeric aptamer complex, and conjugated doxorubicin (Dox) to DVBA-01 (7:1 ratio) using pH-sensitive, covalent linkages. Dox conjugation enhanced the thermal stability of the complex (60.2 versus 46.5°C) and did not decrease affinity for the VN target. The resulting DVBA-01-Dox complex displayed increased cytotoxicity to MDA-MB-231 BC cells that were cultured on plasticware coated with VN (1.8 × 10−6mol/l) relative to uncoated plates (2.4 × 10−6 mol/l), or plates coated with the related protein fibronectin (2.1 × 10−6 mol/l). The VBA-01 aptamer was evaluated for binding to human BC tissue using immunohistochemistry and displayed tissue specific binding and apparent association with BC cells. In contrast, a monoclonal antibody that preferentially binds to multimeric VN primarily stained extracellular matrix and vessel walls of BC tissue. Our results indicate a strong potential for using VN-targeting aptamers to improve drug delivery to treat BC.
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27
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Takahashi M, Wu X, Ho M, Chomchan P, Rossi JJ, Burnett JC, Zhou J. High throughput sequencing analysis of RNA libraries reveals the influences of initial library and PCR methods on SELEX efficiency. Sci Rep 2016; 6:33697. [PMID: 27652575 DOI: 10.1038/srep33697] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 08/31/2016] [Indexed: 12/25/2022] Open
Abstract
The systemic evolution of ligands by exponential enrichment (SELEX) technique is a powerful and effective aptamer-selection procedure. However, modifications to the process can dramatically improve selection efficiency and aptamer performance. For example, droplet digital PCR (ddPCR) has been recently incorporated into SELEX selection protocols to putatively reduce the propagation of byproducts and avoid selection bias that result from differences in PCR efficiency of sequences within the random library. However, a detailed, parallel comparison of the efficacy of conventional solution PCR versus the ddPCR modification in the RNA aptamer-selection process is needed to understand effects on overall SELEX performance. In the present study, we took advantage of powerful high throughput sequencing technology and bioinformatics analysis coupled with SELEX (HT-SELEX) to thoroughly investigate the effects of initial library and PCR methods in the RNA aptamer identification. Our analysis revealed that distinct “biased sequences” and nucleotide composition existed in the initial, unselected libraries purchased from two different manufacturers and that the fate of the “biased sequences” was target-dependent during selection. Our comparison of solution PCR- and ddPCR-driven HT-SELEX demonstrated that PCR method affected not only the nucleotide composition of the enriched sequences, but also the overall SELEX efficiency and aptamer efficacy.
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28
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Bakhshinejad B, Zade HM, Shekarabi HSZ, Neman S. Phage display biopanning and isolation of target-unrelated peptides: in search of nonspecific binders hidden in a combinatorial library. Amino Acids 2016; 48:2699-716. [DOI: 10.1007/s00726-016-2329-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/08/2016] [Indexed: 12/22/2022]
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29
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Xulvi-Brunet R, Campbell GW, Rajamani S, Jiménez JI, Chen IA. Computational analysis of fitness landscapes and evolutionary networks from in vitro evolution experiments. Methods 2016; 106:86-96. [DOI: 10.1016/j.ymeth.2016.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 05/16/2016] [Accepted: 05/18/2016] [Indexed: 11/26/2022] Open
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Urak KT, Shore S, Rockey WM, Chen SJ, McCaffrey AP, Giangrande PH. In vitro RNA SELEX for the generation of chemically-optimized therapeutic RNA drugs. Methods 2016; 103:167-74. [PMID: 26972786 PMCID: PMC4921298 DOI: 10.1016/j.ymeth.2016.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/22/2016] [Accepted: 03/09/2016] [Indexed: 12/13/2022] Open
Abstract
Aptamers are single-stranded DNA or RNA oligonucleotides that can bind with exquisitely high affinity and specificity to target molecules and are thus often referred to as 'nucleic acid' antibodies. Oligonucleotide aptamers are derived through a process of directed chemical evolution called SELEX (Systematic Evolution of Ligands by Exponential enrichment). This chemical equivalent of Darwinian evolution was first described in 1990 by Tuerk & Gold and Ellington & Szostak and has since yielded aptamers for a wide-range of applications, including biosensor technologies, in vitro diagnostics, biomarker discovery, and therapeutics. Since the inception of the original SELEX method, numerous modifications to the protocol have been described to fit the choice of target, specific conditions or applications. Technologies such as high-throughput sequencing methods and microfluidics have also been adapted for SELEX. In this chapter, we outline key steps in the SELEX process for enabling the rapid identification of RNA aptamers for in vivo applications. Specifically, we provide a detailed protocol for the selection of chemically-optimized RNA aptamers using the original in vitro SELEX methodology. In addition, methods for performing next-generation sequencing of the RNAs from each round of selection, based on Illumina sequencing technology, are discussed.
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Affiliation(s)
- Kevin T Urak
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Sabrina Shore
- TriLink BioTechnologies Inc., San Diego, CA 92121, United States
| | - William M Rockey
- Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, United States
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry, and Informatics Institute, University of Missouri-Columbia, Columbia, MO 65211, United States
| | | | - Paloma H Giangrande
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, United States.
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31
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Gijs M, Penner G, Blackler GB, Impens NREN, Baatout S, Luxen A, Aerts AM. Improved Aptamers for the Diagnosis and Potential Treatment of HER2-Positive Cancer. Pharmaceuticals (Basel) 2016; 9:E29. [PMID: 27213406 PMCID: PMC4932547 DOI: 10.3390/ph9020029] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 05/09/2016] [Accepted: 05/10/2016] [Indexed: 02/07/2023] Open
Abstract
Aptamers provide a potential source of alternative targeting molecules for existing antibody diagnostics and therapeutics. In this work, we selected novel DNA aptamers targeting the HER2 receptor by an adherent whole-cell SELEX approach. Individual aptamers were identified by next generation sequencing and bioinformatics analysis. Two aptamers, HeA2_1 and HeA2_3, were shown to bind the HER2 protein with affinities in the nanomolar range. In addition, both aptamers were able to bind with high specificity to HER2-overexpressing cells and HER2-positive tumor tissue samples. Furthermore, we demonstrated that aptamer HeA2_3 is being internalized into cancer cells and has an inhibitory effect on cancer cell growth and viability. In the end, we selected novel DNA aptamers with great potential for the diagnosis and possible treatment of HER2-positive cancer.
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Affiliation(s)
- Marlies Gijs
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
- Cyclotron Research Centre, University of Liège, 4000 Liège, Belgium.
| | - Gregory Penner
- NeoVentures Biotechnology Inc., London, N6A 1A1 ON, Canada.
| | | | | | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
| | - André Luxen
- Cyclotron Research Centre, University of Liège, 4000 Liège, Belgium.
| | - An M Aerts
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN), 2400 Mol, Belgium.
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32
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Thiel WH, Giangrande PH. Analyzing HT-SELEX data with the Galaxy Project tools--A web based bioinformatics platform for biomedical research. Methods 2016; 97:3-10. [PMID: 26481156 PMCID: PMC4792767 DOI: 10.1016/j.ymeth.2015.10.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/12/2015] [Accepted: 10/15/2015] [Indexed: 01/25/2023] Open
Abstract
The development of DNA and RNA aptamers for research as well as diagnostic and therapeutic applications is a rapidly growing field. In the past decade, the process of identifying aptamers has been revolutionized with the advent of high-throughput sequencing (HTS). However, bioinformatics tools that enable the average molecular biologist to analyze these large datasets and expedite the identification of candidate aptamer sequences have been lagging behind the HTS revolution. The Galaxy Project was developed in order to efficiently analyze genome, exome, and transcriptome HTS data, and we have now applied these tools to aptamer HTS data. The Galaxy Project's public webserver is an open source collection of bioinformatics tools that are powerful, flexible, dynamic, and user friendly. The online nature of the Galaxy webserver and its graphical interface allow users to analyze HTS data without compiling code or installing multiple programs. Herein we describe how tools within the Galaxy webserver can be adapted to pre-process, compile, filter and analyze aptamer HTS data from multiple rounds of selection.
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Affiliation(s)
- William H Thiel
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; The François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA 52242, USA.
| | - Paloma H Giangrande
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; The François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA 52242, USA; The Holden Comprehensive Cancer Center, University of Iowa, Iowa City, IA 52242, USA; The Molecular and Cell Biology Program, University of Iowa, Iowa City, IA 52242, USA.
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Chumakov AM, Yuhina ES, Frolova EI, Kravchenko JE, Chumakov SP. Expanding the application potential of DNA aptamers by their functionalization. Russ J Bioorg Chem 2016. [DOI: 10.1134/s1068162016010027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Barfod A, Singh B, Johanson U, Riesbeck K, Kjellbom P. In vitro selection of RNA aptamers directed against protein E: a Haemophilus influenzae adhesin. Mol Biotechnol 2015; 56:714-25. [PMID: 24682699 DOI: 10.1007/s12033-014-9749-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein E (PE) of Haemophilus influenzae is a highly conserved ubiquitous surface protein involved in adhesion to and activation of epithelial cells. The host proteins-vitronectin, laminin, and plasminogen are major targets for PE-dependent interactions with the host. To identify novel inhibitory molecules of PE, we used an in vitro selection method based on systematic evolution of ligands by exponential enrichment known as SELEX in order to select 2'F-modified RNA aptamers that specifically bind to PE. Fourteen selection cycles were performed with decreasing concentrations of PE. Sequencing of clones from the 14th selection round revealed the presence of semiconserved sequence motifs in loop regions of the RNA aptamers. Among these, three aptamers showed the highest affinity to PE in electrophoretic mobility shift assays and in dot blots. These three aptamers also inhibited the interaction of PE with vitronectin as revealed by ELISA. Moreover, pre-treatment of H. influenzae with the aptamers significantly inhibited binding of vitronectin to the bacterial surface. Biacore experiments indicated that one of the aptamers had a higher binding affinity for PE as compared to the other aptamers. Our results show that it is possible to select RNA inhibitors against bacterial adhesins using SELEX in order to inhibit interactions with target proteins.
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Affiliation(s)
- Anders Barfod
- Department of Biochemistry and Structural Biology, CMPS, Lund University, Box 124, 221 00, Lund, Sweden,
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Thiel WH, Thiel KW, Flenker KS, Bair T, Dupuy AJ, McNamara JO, Miller FJ, Giangrande PH. Cell-internalization SELEX: method for identifying cell-internalizing RNA aptamers for delivering siRNAs to target cells. Methods Mol Biol 2015; 1218:187-99. [PMID: 25319652 DOI: 10.1007/978-1-4939-1538-5_11] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
After a decade of work to address cellular uptake, the principal obstacle to RNAi-based therapeutics, there is now well-deserved, renewed optimism about RNAi-based drugs. Phase I and II studies have shown safe, strong, and durable-gene knockdown (80-90%, lasting for a month after a single injection) and/or clinical benefit in treating several liver pathologies. Although promising, these studies have also highlighted the need for robust delivery techniques to develop RNAi therapeutics for treating other organ systems and diseases. Conjugation of siRNAs to cell-specific, synthetic RNA ligands (aptamers) is being proposed as a viable solution to this problem. While encouraging, the extended use of RNA aptamers as a delivery tool for siRNAs awaits the identification of RNA aptamer sequences capable of targeting and entering the cytoplasm of many different cell types. We describe a cell-based selection process for the rapid identification and characterization of RNA aptamers suited for delivering siRNA drugs into the cytoplasm of target cells. This process, termed "cell-internalization SELEX (Systematic Evolution of Ligands by Exponential Enrichment)," entails the combination of multiple sophisticated technologies, including cell culture-based SELEX procedures, next-generation sequencing (NGS), and novel bioinformatics tools.
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Affiliation(s)
- William H Thiel
- Department of Internal Medicine, University of Iowa, 5202 MERF, 200 Hawkins Drive, Iowa City, IA, 52242, USA
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Lee SC, Gedi V, Ha NR, Cho JH, Park HC, Yoon MY. Development of receptor-based inhibitory RNA aptamers for anthrax toxin neutralization. Int J Biol Macromol 2015; 77:293-302. [PMID: 25841381 DOI: 10.1016/j.ijbiomac.2015.03.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 02/27/2015] [Accepted: 03/15/2015] [Indexed: 10/23/2022]
Abstract
Anthrax toxin excreted by Bacillus anthracis is the key causative agent of infectious anthrax disease. In the present study, we targeted the binding of PA to the ATR/TEM8 Von Willebrand factor type A (VWA) domain, which we cloned into Escherichia coli and purified to homogeneity under denaturing conditions. To develop an anthrax toxin inhibitor, we selected and identified short single strand RNA aptamers (approximately 30mer) consisting of different sequences of nucleic acids with a high binding affinity in the 100 nanomolar range against the recombinant ATR/TEM8 VWA domain using systematic evolution of ligands by exponential enrichment (SELEX). Five candidate aptamers were further characterized by several techniques including secondary structural analysis. The inhibitor efficiency (IC50) of one of the aptamers toward anthrax toxin was approximately 5μM in macrophage RAW 264.7 cells, as determined from cytotoxicity analysis by MTT assay. We believe that the candidate aptamers should be useful for blocking the binding of PA to its receptor in order to neutralize anthrax toxin.
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Affiliation(s)
- Sang-Choon Lee
- Department of Chemistry and Research Institute of Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Vinayakumar Gedi
- Department of Chemistry and Research Institute of Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Na-Reum Ha
- Department of Chemistry and Research Institute of Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Jun-Haeng Cho
- Department of Chemistry and Research Institute of Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea
| | - Hae-Chul Park
- Veterinary Drugs & Biologics Division, Animal and Plant Quarantine Agency (QIA), Anyang 430-757, Republic of Korea
| | - Moon-Young Yoon
- Department of Chemistry and Research Institute of Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea.
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Alam KK, Chang JL, Burke DH. FASTAptamer: A Bioinformatic Toolkit for High-throughput Sequence Analysis of Combinatorial Selections. Mol Ther Nucleic Acids 2015; 4:e230. [PMID: 25734917 PMCID: PMC4354339 DOI: 10.1038/mtna.2015.4] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 01/08/2015] [Indexed: 12/22/2022]
Abstract
High-throughput sequence (HTS) analysis of combinatorial selection populations accelerates lead discovery and optimization and offers dynamic insight into selection processes. An underlying principle is that selection enriches high-fitness sequences as a fraction of the population, whereas low-fitness sequences are depleted. HTS analysis readily provides the requisite numerical information by tracking the evolutionary trajectory of individual sequences in response to selection pressures. Unlike genomic data, for which a number of software solutions exist, user-friendly tools are not readily available for the combinatorial selections field, leading many users to create custom software. FASTAptamer was designed to address the sequence-level analysis needs of the field. The open source FASTAptamer toolkit counts, normalizes and ranks read counts in a FASTQ file, compares populations for sequence distribution, generates clusters of sequence families, calculates fold-enrichment of sequences throughout the course of a selection and searches for degenerate sequence motifs. While originally designed for aptamer selections, FASTAptamer can be applied to any selection strategy that can utilize next-generation DNA sequencing, such as ribozyme or deoxyribozyme selections, in vivo mutagenesis and various surface display technologies (peptide, antibody fragment, mRNA, etc.). FASTAptamer software, sample data and a user's guide are available for download at http://burkelab.missouri.edu/fastaptamer.html.
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Affiliation(s)
- Khalid K Alam
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Jonathan L Chang
- 1] Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri, USA [2] Current Address: School of Medicine, University of Missouri, Columbia, Missouri, USA
| | - Donald H Burke
- 1] Department of Biochemistry, University of Missouri, Columbia, Missouri, USA [2] Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri, USA
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Ozer A, Pagano JM, Lis JT. New Technologies Provide Quantum Changes in the Scale, Speed, and Success of SELEX Methods and Aptamer Characterization. Mol Ther Nucleic Acids 2014; 3:e183. [PMID: 25093707 DOI: 10.1038/mtna.2014.34] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 06/10/2014] [Indexed: 12/24/2022]
Abstract
Single-stranded oligonucleotide aptamers have attracted great attention in the past decade because of their diagnostic and therapeutic potential. These versatile, high affinity and specificity reagents are selected by an iterative in vitro process called SELEX, Systematic Evolution of Ligands by Exponential Enrichment. Numerous SELEX methods have been developed for aptamer selections; some that are simple and straightforward, and some that are specialized and complicated. The method of SELEX is crucial for selection of an aptamer with desired properties; however, success also depends on the starting aptamer library, the target molecule, aptamer enrichment monitoring assays, and finally, the analysis and characterization of selected aptamers. Here, we summarize key recent developments in aptamer selection methods, as well as other aspects of aptamer selection that have significant impact on the outcome. We discuss potential pitfalls and limitations in the selection process with an eye to aid researchers in the choice of a proper SELEX strategy, and we highlight areas where further developments and improvements are desired. We believe carefully designed multiplexed selection methods, when complemented with high-throughput downstream analysis and characterization assays, will yield numerous high-affinity aptamers to protein and small molecule targets, and thereby generate a vast array of reagents for probing basic biological mechanisms and implementing new diagnostic and therapeutic applications in the near future.
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Jiang P, Meyer S, Hou Z, Propson NE, Soh HT, Thomson JA, Stewart R. MPBind: a Meta-motif-based statistical framework and pipeline to Predict Binding potential of SELEX-derived aptamers. ACTA ACUST UNITED AC 2014; 30:2665-7. [PMID: 24872422 DOI: 10.1093/bioinformatics/btu348] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
UNLABELLED Aptamers are 'synthetic antibodies' that can bind to target molecules with high affinity and specificity. Aptamers are chemically synthesized and their discovery can be performed completely in vitro, rather than relying on in vivo biological processes, making them well-suited for high-throughput discovery. However, a large fraction of the most enriched aptamers in Systematic Evolution of Ligands by EXponential enrichment (SELEX) rounds display poor binding activity. Here, we present MPBind, a Meta-motif-based statistical framework and pipeline to Predict the BIND: ing potential of SELEX-derived aptamers. Using human embryonic stem cell SELEX-Seq data, MPBind achieved high prediction accuracy for binding potential. Further analysis showed that MPBind is robust to both polymerase chain reaction amplification bias and incomplete sequencing of aptamer pools. These two biases usually confound aptamer analysis. AVAILABILITY AND IMPLEMENTATION MPBind software and documents are available at http://www.morgridge.net/MPBind.html. The human embryonic stem cells whole-cell SELEX-Seq data are available at http://www.morgridge.net/Aptamer/.
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Affiliation(s)
- Peng Jiang
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - Susanne Meyer
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - Zhonggang Hou
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - Nicholas E Propson
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - H Tom Soh
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - James A Thomson
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
| | - Ron Stewart
- Regenerative Biology, Morgridge Institute for Research, Madison, WI 53707, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106 and Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53706, USA
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Szeto K, Latulippe DR, Ozer A, Pagano JM, White BS, Shalloway D, Lis JT, Craighead HG. RAPID-SELEX for RNA aptamers. PLoS One 2013; 8:e82667. [PMID: 24376564 PMCID: PMC3869713 DOI: 10.1371/journal.pone.0082667] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 10/26/2013] [Indexed: 01/11/2023] Open
Abstract
Aptamers are high-affinity ligands selected from DNA or RNA libraries via SELEX, a repetitive in vitro process of sequential selection and amplification steps. RNA SELEX is more complicated than DNA SELEX because of the additional transcription and reverse transcription steps. Here, we report a new selection scheme, RAPID-SELEX (RNA Aptamer Isolation via Dual-cycles SELEX), that simplifies this process by systematically skipping unnecessary amplification steps. Using affinity microcolumns, we were able to complete a multiplex selection for protein targets, CHK2 and UBLCP1, in a third of the time required for analogous selections using a conventional SELEX approach. High-throughput sequencing of the enriched pools from both RAPID and SELEX revealed many identical candidate aptamers from the starting pool of 5×1015 sequences. For CHK2, the same sequence was preferentially enriched in both selections as the top candidate and was found to bind to its respective target. These results demonstrate the efficiency and, most importantly, the robustness of our selection scheme. RAPID provides a generalized approach that can be used with any selection technology to accelerate the rate of aptamer discovery, without compromising selection performance.
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Affiliation(s)
- Kylan Szeto
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York, United States of America
| | - David R Latulippe
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York, United States of America
| | - Abdullah Ozer
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - John M Pagano
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Brian S White
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - David Shalloway
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Harold G Craighead
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York, United States of America
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Gourronc FA, Rockey WM, Thiel WH, Giangrande PH, Klingelhutz AJ. Identification of RNA aptamers that internalize into HPV-16 E6/E7 transformed tonsillar epithelial cells. Virology 2013; 446:325-33. [PMID: 24074596 DOI: 10.1016/j.virol.2013.08.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 06/20/2013] [Accepted: 08/14/2013] [Indexed: 01/09/2023]
Abstract
Human papillomavirus type 16 (HPV-16) associated oropharyngeal cancers are on a significant increase and better therapeutic strategies are needed. The HPV-16 oncogenes E6 and E7 are expressed in HPV-associated cancers and are able to transform human tonsillar epithelial cells (HTECs). We used cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) to select for RNA aptamers that entered into HPV-16 E6/E7-HTECs. After 12 rounds of cell-SELEX, a pool of aptamers was obtained that had significantly greater internalization capacity (~5-fold) into E6/E7-HTECs as compared to primary HTECs or fibroblasts. Analysis of individual aptamers from the pool indicated variable internalization into E6/E7-HTECs (1-8-fold as compared to a negative control). Most of the individual aptamers internalized into E6/E7 and primary HTECs with similar efficiency, while one aptamer exhibited ~3-fold better internalization into E6/E7-HTECs. Aptamers that internalize into cells may be useful for delivering therapeutic agents to HPV-16 associated malignancies.
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Hernandez LI, Flenker KS, Hernandez FJ, Klingelhutz AJ, II JOM, Giangrande PH. Methods for Evaluating Cell-Specific, Cell-Internalizing RNA Aptamers. Pharmaceuticals (Basel) 2013; 6:295-319. [PMID: 23894227 PMCID: PMC3722562 DOI: 10.3390/ph6030295] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Recent clinical trials of small interfering RNAs (siRNAs) highlight the need for robust delivery technologies that will facilitate the successful application of these therapeutics to humans. Arguably, cell targeting by conjugation to cell-specific ligands provides a viable solution to this problem. Synthetic RNA ligands (aptamers) represent an emerging class of pharmaceuticals with great potential for targeted therapeutic applications. For targeted delivery of siRNAs with aptamers, the aptamer-siRNA conjugate must be taken up by cells and reach the cytoplasm. To this end, we have developed cell-based selection approaches to isolate aptamers that internalize upon binding to their cognate receptor on the cell surface. Here we describe methods to monitor for cellular uptake of aptamers. These include: (1) antibody amplification microscopy, (2) microplate-based fluorescence assay, (3) a quantitative and ultrasensitive internalization method (“QUSIM”) and (4) a way to monitor for cytoplasmic delivery using the ribosome inactivating protein-based (RNA-RIP) assay. Collectively, these methods provide a toolset that can expedite the development of aptamer ligands to target and deliver therapeutic siRNAs in vivo.
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Affiliation(s)
- Luiza I. Hernandez
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; E-Mails: (L.I.H); (K.S.F); frank (F.J.H); (J.O.M)
| | - Katie S. Flenker
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; E-Mails: (L.I.H); (K.S.F); frank (F.J.H); (J.O.M)
| | - Frank J. Hernandez
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; E-Mails: (L.I.H); (K.S.F); frank (F.J.H); (J.O.M)
| | - Aloysius J. Klingelhutz
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA; E-Mail:
- Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, USA
- Molecular & Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA
| | - James O. McNamara II
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; E-Mails: (L.I.H); (K.S.F); frank (F.J.H); (J.O.M)
- Molecular & Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA
| | - Paloma H. Giangrande
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA; E-Mails: (L.I.H); (K.S.F); frank (F.J.H); (J.O.M)
- Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, USA
- Molecular & Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-319-384-3242; Fax: +1-319-353-5552
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Doessing H, Hansen LH, Veedu RN, Wengel J, Vester B. Amplification and re-generation of LNA-modified libraries. Molecules 2012; 17:13087-97. [PMID: 23128088 DOI: 10.3390/molecules171113087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 10/31/2012] [Accepted: 11/01/2012] [Indexed: 12/14/2022] Open
Abstract
Locked nucleic acids (LNA) confer high thermal stability and nuclease resistance to oligonucleotides. The discovery of polymerases that accept LNA triphosphates has led us to propose a scheme for the amplification and re-generation of LNA-containing oligonucleotide libraries. Such libraries could be used for in vitro selection of e.g., native LNA aptamers. We maintained an oligonucleotide library encoding 40 randomized positions with LNA ATP, GTP, CTP, and TTP for 7 rounds of ‘mock’ in vitro selection in the absence of a target and analyzed the sequence composition after rounds 1, 4 and 7. We observed a decrease in LNA-A content from 20.5% in round 1 to 6.6% in round 7. This decrease was accompanied by a substantial bias against successive LNA-As (poly-LNA adenosine tracts) and a relative over-representation of single LNA-As. Maintaining a library with LNA TTP yielded similar results. Together, these results suggest that dispersed LNA monomers are tolerated in our in vitro selection protocol, and that LNA-modified libraries can be sustained for up to at least seven selection rounds, albeit at reduced levels. This enables the discovery of native LNA aptamers and similar oligonucleotide structures.
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Kang D, Wang J, Zhang W, Song Y, Li X, Zou Y, Zhu M, Zhu Z, Chen F, Yang CJ. Selection of DNA aptamers against glioblastoma cells with high affinity and specificity. PLoS One 2012; 7:e42731. [PMID: 23056171 PMCID: PMC3462804 DOI: 10.1371/journal.pone.0042731] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 07/11/2012] [Indexed: 12/31/2022] Open
Abstract
Background Glioblastoma is the most common and most lethal form of brain tumor in human. Unfortunately, there is still no effective therapy to this fatal disease and the median survival is generally less than one year from the time of diagnosis. Discovery of ligands that can bind specifically to this type of tumor cells will be of great significance to develop early molecular imaging, targeted delivery and guided surgery methods to battle this type of brain tumor. Methodology/Principal Findings We discovered two target-specific aptamers named GBM128 and GBM131 against cultured human glioblastoma cell line U118-MG after 30 rounds selection by a method called cell-based Systematic Evolution of Ligands by EXponential enrichment (cell-SELEX). These two aptamers have high affinity and specificity against target glioblastoma cells. They neither recognize normal astraglial cells, nor do they recognize other normal and cancer cell lines tested. Clinical tissues were also tested and the results showed that these two aptamers can bind to different clinical glioma tissues but not normal brain tissues. More importantly, binding affinity and selectivity of these two aptamers were retained in complicated biological environment. Conclusion/Significance The selected aptamers could be used to identify specific glioblastoma biomarkers. Methods of molecular imaging, targeted drug delivery, ligand guided surgery can be further developed based on these ligands for early detection, targeted therapy, and guided surgery of glioblastoma leading to effective treatment of glioblastoma.
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Affiliation(s)
- Dezhi Kang
- Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China
- * E-mail: (DK); (CJY)
| | - Jiangjie Wang
- Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China
| | - Weiyun Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Science and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, China
| | - Yanling Song
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Science and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, China
| | - Xilan Li
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Science and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, China
| | - Yuan Zou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Science and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, China
| | - Mingtao Zhu
- Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China
| | - Zhi Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Science and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, China
| | - Fuyong Chen
- Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, China
| | - Chaoyong James Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Science and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, China
- * E-mail: (DK); (CJY)
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Thiel WH, Bair T, Peek AS, Liu X, Dassie J, Stockdale KR, Behlke MA, Miller FJ, Giangrande PH. Rapid identification of cell-specific, internalizing RNA aptamers with bioinformatics analyses of a cell-based aptamer selection. PLoS One 2012; 7:e43836. [PMID: 22962591 PMCID: PMC3433472 DOI: 10.1371/journal.pone.0043836] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/30/2012] [Indexed: 01/05/2023] Open
Abstract
Background The broad applicability of RNA aptamers as cell-specific delivery tools for therapeutic reagents depends on the ability to identify aptamer sequences that selectively access the cytoplasm of distinct cell types. Towards this end, we have developed a novel approach that combines a cell-based selection method (cell-internalization SELEX) with high-throughput sequencing (HTS) and bioinformatics analyses to rapidly identify cell-specific, internalization-competent RNA aptamers. Methodology/Principal Findings We demonstrate the utility of this approach by enriching for RNA aptamers capable of selective internalization into vascular smooth muscle cells (VSMCs). Several rounds of positive (VSMCs) and negative (endothelial cells; ECs) selection were performed to enrich for aptamer sequences that preferentially internalize into VSMCs. To identify candidate RNA aptamer sequences, HTS data from each round of selection were analyzed using bioinformatics methods: (1) metrics of selection enrichment; and (2) pairwise comparisons of sequence and structural similarity, termed edit and tree distance, respectively. Correlation analyses of experimentally validated aptamers or rounds revealed that the best cell-specific, internalizing aptamers are enriched as a result of the negative selection step performed against ECs. Conclusions and Significance We describe a novel approach that combines cell-internalization SELEX with HTS and bioinformatics analysis to identify cell-specific, cell-internalizing RNA aptamers. Our data highlight the importance of performing a pre-clear step against a non-target cell in order to select for cell-specific aptamers. We expect the extended use of this approach to enable the identification of aptamers to a multitude of different cell types, thereby facilitating the broad development of targeted cell therapies.
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Affiliation(s)
- William H. Thiel
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Thomas Bair
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Andrew S. Peek
- Roche Molecular Systems, San Francisco, California, United States of America
| | - Xiuying Liu
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Justin Dassie
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Katie R. Stockdale
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Mark A. Behlke
- Integrated DNA Technologies, Coralville, Iowa, United States of America
| | - Francis J. Miller
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Paloma H. Giangrande
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Department of Radiation Oncology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Matochko WL, Chu K, Jin B, Lee SW, Whitesides GM, Derda R. Deep sequencing analysis of phage libraries using Illumina platform. Methods 2012; 58:47-55. [PMID: 22819855 DOI: 10.1016/j.ymeth.2012.07.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 07/11/2012] [Indexed: 11/25/2022] Open
Abstract
This paper presents an analysis of phage-displayed libraries of peptides using Illumina. We describe steps for the preparation of short DNA fragments for deep sequencing and MatLab software for the analysis of the results. Screening of peptide libraries displayed on the surface of bacteriophage (phage display) can be used to discover peptides that bind to any target. The key step in this discovery is the analysis of peptide sequences present in the library. This analysis is usually performed by Sanger sequencing, which is labor intensive and limited to examination of a few hundred phage clones. On the other hand, Illumina deep-sequencing technology can characterize over 10(7) reads in a single run. We applied Illumina sequencing to analyze phage libraries. Using PCR, we isolated the variable regions from M13KE phage vectors from a phage display library. The PCR primers contained (i) sequences flanking the variable region, (ii) barcodes, and (iii) variable 5'-terminal region. We used this approach to examine how diversity of peptides in phage display libraries changes as a result of amplification of libraries in bacteria. Using HiSeq single-end Illumina sequencing of these fragments, we acquired over 2×10(7) reads, 57 base pairs (bp) in length. Each read contained information about the barcode (6bp), one complimentary region (12bp) and a variable region (36bp). We applied this sequencing to a model library of 10(6) unique clones and observed that amplification enriches ∼150 clones, which dominate ∼20% of the library. Deep sequencing, for the first time, characterized the collapse of diversity in phage libraries. The results suggest that screens based on repeated amplification and small-scale sequencing identify a few binding clones and miss thousands of useful clones. The deep sequencing approach described here could identify under-represented clones in phage screens. It could also be instrumental in developing new screening strategies, which can preserve diversity of phage clones and identify ligands previously lost in phage display screens.
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Affiliation(s)
- Wadim L Matochko
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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Zhang Q, Landgraf R. Selecting Molecular Recognition. What Can Existing Aptamers Tell Us about Their Inherent Recognition Capabilities and Modes of Interaction? Pharmaceuticals (Basel) 2012; 5:493-513. [PMID: 24281560 DOI: 10.3390/ph5050493] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/19/2012] [Accepted: 05/10/2012] [Indexed: 01/02/2023] Open
Abstract
The use of nucleic acid derived aptamers has rapidly expanded since the introduction of SELEX in 1990. Nucleic acid aptamers have demonstrated their ability to target a broad range of molecules in ways that rival antibodies, but advances have been very uneven for different biochemical classes of targets, and clinical applications have been slow to emerge. What sets different aptamers apart from each other and from rivaling molecular recognition platforms, specifically proteins? What advantages do aptamers as a reagent class offer, and how do the chemical properties and selection procedures of aptamers influence their function? Do the building blocks of nucleic acid aptamers dictate inherent limitations in the nature of molecular targets, and do existing aptamers give us insight in how these challenges might be overcome? This review is written as an introduction for potential endusers of aptamer technology who are evaluating the advantages of aptamers as a versatile, affordable, yet highly expandable platform to target a broad range of biological processes or interactions.
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Thiel KW, Hernandez LI, Dassie JP, Thiel WH, Liu X, Stockdale KR, Rothman AM, Hernandez FJ, McNamara JO, Giangrande PH. Delivery of chemo-sensitizing siRNAs to HER2+-breast cancer cells using RNA aptamers. Nucleic Acids Res 2012; 40:6319-37. [PMID: 22467215 PMCID: PMC3401474 DOI: 10.1093/nar/gks294] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Human epidermal growth factor receptor 2 (HER2) expression in breast cancer is associated with an aggressive phenotype and poor prognosis, making it an appealing therapeutic target. Trastuzumab, an HER2 antibody-based inhibitor, is currently the leading targeted treatment for HER2(+)-breast cancers. Unfortunately, many patients inevitably develop resistance to the therapy, highlighting the need for alternative targeted therapeutic options. In this study, we used a novel, cell-based selection approach for isolating 'cell-type specific', 'cell-internalizing RNA ligands (aptamers)' capable of delivering therapeutic small interfering RNAs (siRNAs) to HER2-expressing breast cancer cells. RNA aptamers with the greatest specificity and internalization potential were covalently linked to siRNAs targeting the anti-apoptotic gene, Bcl-2. We demonstrate that, when applied to cells, the HER2 aptamer-Bcl-2 siRNA conjugates selectively internalize into HER2(+)-cells and silence Bcl-2 gene expression. Importantly, Bcl-2 silencing sensitizes these cells to chemotherapy (cisplatin) suggesting a potential new therapeutic approach for treating breast cancers with HER2(+)-status. In summary, we describe a novel cell-based selection methodology that enables the identification of cell-internalizing RNA aptamers for targeting therapeutic siRNAs to HER2-expressing breast cancer cells. The future refinement of this technology may promote the widespread use of RNA-based reagents for targeted therapeutic applications.
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Affiliation(s)
- Kristina W Thiel
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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