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Oscorbin IP, Filipenko ML. A Novel Thermostable and Processive Reverse Transcriptase from a Group II Intron of Anoxybacillus flavithermus. Biomolecules 2023; 14:49. [PMID: 38254649 PMCID: PMC10813441 DOI: 10.3390/biom14010049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024] Open
Abstract
Reverse transcriptases (RTs) are a family of enzymes that synthesize DNA using an RNA template and are involved in retrovirus propagation and telomere lengthening. In vitro, RTs are widely applied in various methods, including RNA-seq, RT-PCR, and RT-LAMP. Thermostable RTs from bacterial group II introns are promising tools for biotechnology due to their higher thermostability, fidelity, and processivity compared to commonly used M-MuLV RT and its mutants. However, the diversity of group II intron-encoded RTs is still understudied. In this work, we biochemically characterized a novel RT from a thermophilic bacterium, Anoxybacillus flavithermus, which was isolated from a hot spring in New Zealand and has an optimal growth temperature of around 60 °C. The cloned RT, named Afl RT, retained approximately 40% of the specific activity after a 45 min incubation at 50 °C. The optimal pH was 8.5, the optimal temperature was between 45 and 50 °C, and Mn2+ ions were found to be an optimal cofactor. The processivity analysis with MS2 phage gRNA (3569 b) demonstrated that Afl RT elongated fully up to 36% of the template molecules. In reverse transcription and RT-qLAMP, the enzyme allowed up to 10 copies of MS2 phage genomic RNA to be detected per reaction. Thus, Afl RT holds great potential for a variety of practical applications that require the use of thermostable and processive RTs.
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Affiliation(s)
- Igor P. Oscorbin
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences (ICBFM SB RAS), 8 Lavrentiev Avenue, 630090 Novosibirsk, Russia;
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2
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Casmil IC, Huang C, Blakney AK. A duplex droplet digital PCR assay for absolute quantification and characterization of long self-amplifying RNA. Sci Rep 2023; 13:19050. [PMID: 37923834 PMCID: PMC10624827 DOI: 10.1038/s41598-023-46314-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 10/30/2023] [Indexed: 11/06/2023] Open
Abstract
Self-amplifying messenger ribonucleic acid (saRNA) provides extended expression of genes of interest by encoding an alphavirus-derived RNA replicase and thus is 2-3 times larger than conventional messenger RNA. However, quality assessment of long RNA transcripts is challenging using standard techniques. Here, we utilized a multiplex droplet digital polymerase chain reaction (ddPCR) assay to assess the quality of saRNA produced from an in vitro transcription reaction and the replication kinetics in human cell lines. Using the one-step reverse transcription ddPCR, we show that an in vitro transcription generates 50-60% full-length saRNA transcripts. However, we note that the two-step reverse transcription ddPCR assay results in a 20% decrease from results obtained using the one-step and confirmed using capillary gel electrophoresis. Additionally, we provided three formulas that differ in the level of stringency and assumptions made to calculate the fraction of intact saRNA. Using ddPCR, we also showed that subgenomic transcripts of saRNA were 19-to-108-fold higher than genomic transcripts at different hours post-transfection of mammalian cells in copies. Therefore, we demonstrate that multiplex ddPCR is well suited for quality assessment of long RNA and replication kinetics of saRNA based on absolute quantification.
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Affiliation(s)
- Irafasha C Casmil
- Michael Smith Laboratories, School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Cynthia Huang
- Michael Smith Laboratories, School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Anna K Blakney
- Michael Smith Laboratories, School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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3
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Verwilt J, Mestdagh P, Vandesompele J. Artifacts and biases of the reverse transcription reaction in RNA sequencing. RNA (NEW YORK, N.Y.) 2023; 29:889-897. [PMID: 36990512 DOI: 10.1261/rna.079623.123] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
RNA sequencing has spurred a significant number of research areas in recent years. Most protocols rely on synthesizing a more stable complementary DNA (cDNA) copy of the RNA molecule during the reverse transcription reaction. The resulting cDNA pool is often wrongfully assumed to be quantitatively and molecularly similar to the original RNA input. Sadly, biases and artifacts confound the resulting cDNA mixture. These issues are often overlooked or ignored in the literature by those that rely on the reverse transcription process. In this review, we confront the reader with intra- and intersample biases and artifacts caused by the reverse transcription reaction during RNA sequencing experiments. To fight the reader's despair, we also provide solutions to most issues and inform on good RNA sequencing practices. We hope the reader can use this review to their advantage, thereby contributing to scientifically sound RNA studies.
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Affiliation(s)
- Jasper Verwilt
- OncoRNALab, Cancer Research Institute Ghent, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Center for Medical Genetics, Ghent University, 9000 Ghent, Belgium
| | - Pieter Mestdagh
- OncoRNALab, Cancer Research Institute Ghent, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Center for Medical Genetics, Ghent University, 9000 Ghent, Belgium
| | - Jo Vandesompele
- OncoRNALab, Cancer Research Institute Ghent, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Center for Medical Genetics, Ghent University, 9000 Ghent, Belgium
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4
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Huber LB, Betz K, Marx A. Reverse Transcriptases: From Discovery and Applications to Xenobiology. Chembiochem 2023; 24:e202200521. [PMID: 36354312 DOI: 10.1002/cbic.202200521] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/09/2022] [Indexed: 11/12/2022]
Abstract
Reverse transcriptases are DNA polymerases that can use RNA as a template for DNA synthesis. They thus catalyze the reverse of transcription. Although discovered in 1970, reverse transcriptases are still of great interest and are constantly being further developed for numerous modern research approaches. They are frequently used in biotechnological and molecular diagnostic applications. In this review, we describe the discovery of these fascinating enzymes and summarize research results and applications ranging from molecular cloning, direct virus detection, and modern sequencing methods to xenobiology.
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Affiliation(s)
- Luisa B Huber
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany
| | - Karin Betz
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany
| | - Andreas Marx
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany
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Vereecke N, Woźniak A, Pauwels M, Coppens S, Nauwynck H, Cybulski P, Theuns S, Stadejek T. Successful Whole Genome Nanopore Sequencing of Swine Influenza A Virus (swIAV) Directly from Oral Fluids Collected in Polish Pig Herds. Viruses 2023; 15:v15020435. [PMID: 36851649 PMCID: PMC9962634 DOI: 10.3390/v15020435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/20/2023] [Accepted: 01/31/2023] [Indexed: 02/09/2023] Open
Abstract
Influenza A virus (IAV) is a single-stranded, negative-sense RNA virus and a common cause of seasonal flu in humans. Its genome comprises eight RNA segments that facilitate reassortment, resulting in a great variety of IAV strains. To study these processes, the genetic code of each segment should be unraveled. Fortunately, new third-generation sequencing approaches allow for cost-efficient sequencing of IAV segments. Sequencing success depends on various factors, including proper sample storage and processing. Hence, this work focused on the effect of storage of oral fluids and swIAV sequencing. Oral fluids (n = 13) from 2017 were stored at -22 °C and later transferred to -80 °C. Other samples (n = 21) were immediately stored at -80 °C. A reverse transcription quantitative PCR (RT-qPCR) pre- and post-storage was conducted to assess IAV viral loads. Next, samples were subjected to two IAV long-read nanopore sequencing methods to evaluate success in this complex matrix. A significant storage-associated loss of swIAV loads was observed. Still, a total of 17 complete and 6 near-complete Polish swIAV genomes were obtained. Genotype T, (H1avN2, seven herds), P (H1N1pdm09, two herds), U (H1avN1, three herds), and A (H1avN1, 1 herd) were circulated on Polish farms. In conclusion, oral fluids can be used for long-read swIAV sequencing when considering appropriate storage and segment amplification protocols, which allows us to monitor swIAV in an animal-friendly and cost-efficient manner.
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Affiliation(s)
- Nick Vereecke
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium
- PathoSense BV, 2500 Lier, Belgium
- Correspondence: (N.V.); (A.W.); (T.S.)
| | - Aleksandra Woźniak
- Department of Pathology and Veterinary Diagnostic, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, 02-776 Warsaw, Poland
- Correspondence: (N.V.); (A.W.); (T.S.)
| | | | | | - Hans Nauwynck
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium
- PathoSense BV, 2500 Lier, Belgium
| | - Piotr Cybulski
- Goodvalley Agro S.A., Dworcowa 25, 77-320 Przechlewo, Poland
| | - Sebastiaan Theuns
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium
- PathoSense BV, 2500 Lier, Belgium
| | - Tomasz Stadejek
- Department of Pathology and Veterinary Diagnostic, Institute of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, 02-776 Warsaw, Poland
- Correspondence: (N.V.); (A.W.); (T.S.)
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Qin X, Wang X, Xu K, Zhang Y, Tian H, Li Y, Qi B, Yang X. Quantitative analysis of miRNAs using SplintR ligase-mediated ligation of complementary-pairing probes enhanced by RNase H (SPLICER)-qPCR. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 31:241-255. [PMID: 36700047 PMCID: PMC9842969 DOI: 10.1016/j.omtn.2022.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022]
Abstract
Here, a method using SplintR ligase-mediated ligation of complementary-pairing probes enhanced by RNase H (SPLICER) for miRNAs quantification was established. The strategy has two steps: (1) ligation of two DNA probes specifically hybridize to target miRNA and (2) qPCR amplifying the ligated probe. The miRNA-binding regions of the probes are stem-looped, a motif significantly reduces nonspecific ligation at high ligation temperature (65°C). The ends of the probes are designed complementary to form a paired probe, facilitating the recognition of target miRNAs with low concentrations. RNase H proved to be able to stabilize the heteroduplex formed by the probe and target miRNA, contributing to enhanced sensitivity (limit of detection = 60 copies). High specificity (discriminating homology miRNAs differing only one nucleotide), wide dynamic range (seven orders of magnitude) and ability to accurately detect plant miRNAs (immune to hindrance of 2'-O-methyl moiety) enable SPLICER comparable with the commercially available TaqMan and miRCURY assays. SYBR green I, rather than expensive hydrolysis or locked nucleic acid probes indispensable to TaqMan and miRCURY assays, is adequate for SPLICER. The method was efficient (<1 h), economical ($7 per sample), and robust (able to detect xeno-miRNAs in mammalian bodies), making it a powerful tool for molecular diagnosis and corresponding therapy.
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Affiliation(s)
- Xinshu Qin
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710062, Shaanxi, China
| | - Xingyu Wang
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710062, Shaanxi, China,Corresponding author: Xingyu Wang, College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710054, Shaanxi, China.
| | - Ke Xu
- Department of Joint Surgery, Hong Hui Hospital, Xi’an Jiaotong University, Xi’an 710054, Shaanxi, China
| | - Yi Zhang
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Hongye Tian
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710062, Shaanxi, China
| | - Yinglei Li
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710062, Shaanxi, China
| | - Bangran Qi
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710062, Shaanxi, China
| | - Xingbin Yang
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710062, Shaanxi, China,Corresponding author: Xingbin Yang, College of Food Engineering and Nutritional Science, Shaanxi Normal University, No. 620 West Chang’an Avenue, Xi’an 710054, Shaanxi, China.
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7
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Hepatic RNA adduction derived from metabolic activation of retrorsine in vitro and in vivo. Chem Biol Interact 2022; 365:110047. [DOI: 10.1016/j.cbi.2022.110047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 06/21/2022] [Accepted: 07/13/2022] [Indexed: 11/19/2022]
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8
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RT-qPCR Detection of SARS-CoV-2: No Need for a Dedicated Reverse Transcription Step. Int J Mol Sci 2022; 23:ijms23031303. [PMID: 35163227 PMCID: PMC8835954 DOI: 10.3390/ijms23031303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/27/2021] [Accepted: 01/21/2022] [Indexed: 11/16/2022] Open
Abstract
Reverse transcription of RNA coupled to amplification of the resulting cDNA by the polymerase chain reaction (RT-PCR) is one of the principal molecular technologies in use today, with applications across all areas of science and medicine. In its real-time, fluorescence-based usage (RT-qPCR), it has long been a core technology driving the accurate, rapid and sensitive laboratory diagnosis of infectious diseases. However, RT-qPCR protocols have changed little over the past 30 years, with the RT step constituting a significant percentage of the time taken to complete a typical RT-qPCR assay. When applied to research investigations, reverse transcription has been evaluated by criteria such as maximum yield, length of transcription, fidelity, and faithful representation of an RNA pool. Crucially, however, these are of less relevance in a diagnostic RT-PCR test, where speed and sensitivity are the prime RT imperatives, with specificity contributed by the PCR component. We propose a paradigm shift that omits the requirement for a separate high-temperature RT step at the beginning of an RT-qPCR assay. This is achieved by means of an innovative protocol that incorporates suitable reagents with a revised primer and amplicon design and we demonstrate a proof of principle that incorporates the RT step as part of the PCR assay setup at room temperature. Use of this modification as part of a diagnostic assay will of course require additional characterisation, validation and optimisation of the PCR step. Combining this revision with our previous development of fast qPCR protocols allows completion of a 40 cycle RT-qPCR run on a suitable commercial instrument in approximately 15 min. Even faster times, in combination with extreme PCR procedures, can be achieved.
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9
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Oscorbin IP, Filipenko ML. M-MuLV reverse transcriptase: Selected properties and improved mutants. Comput Struct Biotechnol J 2021; 19:6315-6327. [PMID: 34900141 PMCID: PMC8640165 DOI: 10.1016/j.csbj.2021.11.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 11/12/2021] [Accepted: 11/18/2021] [Indexed: 11/06/2022] Open
Abstract
Reverse transcriptases (RTs) are enzymes synthesizing DNA using RNA as the template and serving as the standard tools in modern biotechnology and molecular diagnostics. To date, the most commonly used reverse transcriptase is the enzyme from Moloney murine leukemia virus, M-MuLV RT. Since its discovery, M-MuLV RT has become indispensable for modern RNA studies; the range of M-MuLV RT applications is vast, from scientific tasks to clinical testing of human pathogens. This review will give a brief description of the structure, thermal stability, processivity, and fidelity, focusing on improving M-MuLV RT for practical usage.
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Affiliation(s)
- Igor P Oscorbin
- Institute of Chemical Biology and Fundamental Medicine SB RAS, 8 Lavrentiev Avenue, Novosibirsk 630090, Russia
| | - Maxim L Filipenko
- Institute of Chemical Biology and Fundamental Medicine SB RAS, 8 Lavrentiev Avenue, Novosibirsk 630090, Russia
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10
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Barrass SV, Butcher SJ. Advances in high-throughput methods for the identification of virus receptors. Med Microbiol Immunol 2019; 209:309-323. [PMID: 31865406 PMCID: PMC7248041 DOI: 10.1007/s00430-019-00653-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 12/02/2019] [Indexed: 12/26/2022]
Abstract
Viruses have evolved many mechanisms to invade host cells and establish successful infections. The interaction between viral attachment proteins and host cell receptors is the first and decisive step in establishing such infections, initiating virus entry into the host cells. Therefore, the identification of host receptors is fundamental in understanding pathogenesis and tissue tropism. Furthermore, receptor identification can inform the development of antivirals, vaccines, and diagnostic technologies, which have a substantial impact on human health. Nevertheless, due to the complex nature of virus entry, the redundancy in receptor usage, and the limitations in current identification methods, many host receptors remain elusive. Recent advances in targeted gene perturbation, high-throughput screening, and mass spectrometry have facilitated the discovery of virus receptors in recent years. In this review, we compare the current methods used within the field to identify virus receptors, focussing on genomic- and interactome-based approaches.
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Affiliation(s)
- Sarah V Barrass
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Bioscience Research Programme and Helsinki Institute of Life Sciences, Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland.
| | - Sarah J Butcher
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Bioscience Research Programme and Helsinki Institute of Life Sciences, Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland.
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Heller RC, Chung S, Crissy K, Dumas K, Schuster D, Schoenfeld TW. Engineering of a thermostable viral polymerase using metagenome-derived diversity for highly sensitive and specific RT-PCR. Nucleic Acids Res 2019; 47:3619-3630. [PMID: 30767012 PMCID: PMC6468311 DOI: 10.1093/nar/gkz104] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/07/2019] [Accepted: 02/07/2019] [Indexed: 12/02/2022] Open
Abstract
Reverse transcription is an essential initial step in the analysis of RNA for most PCR-based amplification and detection methods. Despite advancements in these technologies, efficient conversion of RNAs that form stable secondary structures and double-stranded RNA targets remains challenging as retroviral-derived reverse transcriptases are often not sufficiently thermostable to catalyze synthesis at temperatures high enough to completely relax these structures. Here we describe the engineering and improvement of a thermostable viral family A polymerase with inherent reverse transcriptase activity for use in RT-PCR. Using the 3173 PyroPhage polymerase, previously identified from hot spring metagenomic sampling, and additional thermostable orthologs as a source of natural diversity, we used gene shuffling for library generation and screened for novel variants that retain high thermostability and display elevated reverse transcriptase activity. We then created a fusion enzyme between a high-performing variant polymerase and the 5′→3′ nuclease domain of Taq DNA polymerase that provided compatibility with probe-based detection chemistries and enabled highly sensitive detection of structured RNA targets. This technology enables a flexible single-enzyme RT-PCR system that has several advantages compared with standard heat-labile reverse transcription methods.
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Affiliation(s)
- Ryan C Heller
- Department of Research and Development, QIAGEN Beverly, 100 Cummings Center, Suite 407J, Beverly, MA 01915, USA
| | - Suhman Chung
- Department of Research and Development, QIAGEN Beverly, 100 Cummings Center, Suite 407J, Beverly, MA 01915, USA
| | - Katarzyna Crissy
- Department of Research and Development, QIAGEN Beverly, 100 Cummings Center, Suite 407J, Beverly, MA 01915, USA
| | - Kyle Dumas
- Department of Research and Development, QIAGEN Beverly, 100 Cummings Center, Suite 407J, Beverly, MA 01915, USA
| | - David Schuster
- Department of Research and Development, QIAGEN Beverly, 100 Cummings Center, Suite 407J, Beverly, MA 01915, USA
| | - Thomas W Schoenfeld
- Department of Research and Development, QIAGEN Beverly, 100 Cummings Center, Suite 407J, Beverly, MA 01915, USA
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Pham QN, Trinh KTL, Tran NKS, Park TS, Lee NY. Fabrication of 3D continuous-flow reverse-transcription polymerase chain reaction microdevice integrated with on-chip fluorescence detection for semi-quantitative assessment of gene expression. Analyst 2018; 143:5692-5701. [PMID: 30318528 DOI: 10.1039/c8an01739e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We fabricate a three-dimensional (3D) microdevice operated with minimal peripheral accessories, including a portable pump for semi-automated sample delivery and a single heater for temperature control, for performing reverse transcription polymerase chain reaction (RT-PCR) integrated with a downstream fluorescence detection module for semi-quantitative assessment of gene expression. The microdevice was fabricated by wrapping a polytetrafluoroethylene (PTFE) tube around a pre-designed polycarbonate mold to create a seamless microchannel for both the reverse transcription (RT) of RNA and the amplification of complementary DNA. In addition, a silicone tube, which underwent a two-step surface modification mediated by polyethyleneimine and glutaraldehyde coating, was connected at the outlet to capture amplicons downstream of the PTFE tube for on-site fluorescence detection. This fabrication method enabled continuous-flow RT-PCR (CF RT-PCR) using the 3D CF RT-PCR microdevice as a reactor, a single heater for the temperature control of both RT and PCR processes, and a disposable plastic syringe for semi-automated sample delivery. The microdevice was successfully implemented for the identification of the β-actin gene, a constitutively expressed gene in all cells, and the sphingosine-1-phosphate lyase 1 gene, a potential pharmacological target gene in the diagnosis of cancer, diabetes, and atherosclerosis. This portable integrated microdevice offers a potential approach towards preliminary studies of gene expression and identification of RNA viruses.
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Affiliation(s)
- Quang Nghia Pham
- Department of BioNano Technology, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, Korea.
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Assays for precise quantification of total (including short) and elongated HIV-1 transcripts. J Virol Methods 2016; 242:1-8. [PMID: 28034670 DOI: 10.1016/j.jviromet.2016.12.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/21/2016] [Accepted: 12/23/2016] [Indexed: 11/24/2022]
Abstract
Despite intensive study, it is unclear which mechanisms are responsible for latent HIV infection in vivo. One potential mechanism is inhibition of HIV transcriptional elongation, which results in short abortive transcripts containing the trans-activation response (TAR) region. Because the relative levels of total (including short) and processive transcripts provide measures of HIV transcriptional initiation and elongation, there is a compelling need for techniques that accurately measure both. Nonetheless, prior assays for total transcripts have been semi-quantitative and have seen limited application to patient samples. This manuscript reports the validation of quantitative reverse transcription (RT) droplet digital PCR assays for measurement of total (TAR) and processive (R-U5/gag) HIV transcripts. Traditional RT priming strategies can efficiently detect the TAR region on long HIV transcripts but detect <4% of true short transcripts. The TAR assay presented here utilizes an initial polyadenylation step, which provides an accessible RT priming site and detects short and long transcripts with approximately equal efficiency (70%). By applying these assays to blood samples from 8 ART-treated HIV+ individuals, total HIV transcripts were detected at levels >10-fold higher than elongated transcripts, implying a substantial block to transcriptional elongation in vivo. This approach may be applied to other difficult-to-prime RNA targets.
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Friedensohn S, Khan TA, Reddy ST. Advanced Methodologies in High-Throughput Sequencing of Immune Repertoires. Trends Biotechnol 2016; 35:203-214. [PMID: 28341036 DOI: 10.1016/j.tibtech.2016.09.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/19/2016] [Accepted: 09/30/2016] [Indexed: 11/19/2022]
Abstract
In recent years, major efforts have been made to develop sophisticated experimental and bioinformatic workflows for sequencing adaptive immune repertoires. The immunological insight gained has been applied to fields as varied as lymphocyte biology, immunodiagnostics, vaccines, cancer immunotherapy, and antibody engineering. In this review, we provide a detailed overview of these advanced methodologies, focusing specifically on strategies to reduce sequencing errors and bias and to achieve high-throughput pairing of variable regions (e.g., heavy-light or alpha-beta chains). In addition, we highlight recent technologies for single-cell transcriptome sequencing that can be integrated with immune repertoires. Finally, we provide a perspective on advanced immune repertoire sequencing and its ability to impact basic immunology, biopharmaceutical drug discovery and development, and cancer immunotherapy.
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Affiliation(s)
- Simon Friedensohn
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | - Tarik A Khan
- Pharmaceutical Development & Supplies Biologics Europe, F. Hoffman-La Roche Ltd, Basel, Switzerland
| | - Sai T Reddy
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland.
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15
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Nottingham RM, Wu DC, Qin Y, Yao J, Hunicke-Smith S, Lambowitz AM. RNA-seq of human reference RNA samples using a thermostable group II intron reverse transcriptase. RNA (NEW YORK, N.Y.) 2016; 22:597-613. [PMID: 26826130 PMCID: PMC4793214 DOI: 10.1261/rna.055558.115] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 12/30/2015] [Indexed: 05/20/2023]
Abstract
Next-generation RNA sequencing (RNA-seq) has revolutionized our ability to analyze transcriptomes. Current RNA-seq methods are highly reproducible, but each has biases resulting from different modes of RNA sample preparation, reverse transcription, and adapter addition, leading to variability between methods. Moreover, the transcriptome cannot be profiled comprehensively because highly structured RNAs, such as tRNAs and snoRNAs, are refractory to conventional RNA-seq methods. Recently, we developed a new method for strand-specific RNA-seq using thermostable group II intron reverse transcriptases (TGIRTs). TGIRT enzymes have higher processivity and fidelity than conventional retroviral reverse transcriptases plus a novel template-switching activity that enables RNA-seq adapter addition during cDNA synthesis without using RNA ligase. Here, we obtained TGIRT-seq data sets for well-characterized human RNA reference samples and compared them to previous data sets obtained for these RNAs by the Illumina TruSeq v2 and v3 methods. We find that TGIRT-seq recapitulates the relative abundance of human transcripts and RNA spike-ins in ribo-depleted, fragmented RNA samples comparably to non-strand-specific TruSeq v2 and better than strand-specific TruSeq v3. Moreover, TGIRT-seq is more strand specific than TruSeq v3 and eliminates sampling biases from random hexamer priming, which are inherent to TruSeq. The TGIRT-seq data sets also show more uniform 5' to 3' gene coverage and identify more splice junctions, particularly near the 5' ends of mRNAs, than do the TruSeq data sets. Finally, TGIRT-seq enables the simultaneous profiling of mRNAs and lncRNAs in the same RNA-seq experiment as structured small ncRNAs, including tRNAs, which are essentially absent with TruSeq.
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Affiliation(s)
- Ryan M Nottingham
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, 78712, USA Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Douglas C Wu
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, 78712, USA Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Yidan Qin
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, 78712, USA Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Jun Yao
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, 78712, USA Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Scott Hunicke-Smith
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Alan M Lambowitz
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, 78712, USA Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
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Yadav RK, Barbi F, Ziller A, Luis P, Marmeisse R, Reddy MS, Fraissinet-Tachet L. Construction of sized eukaryotic cDNA libraries using low input of total environmental metatranscriptomic RNA. BMC Biotechnol 2014; 14:80. [PMID: 25183040 PMCID: PMC4170940 DOI: 10.1186/1472-6750-14-80] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 08/21/2014] [Indexed: 11/25/2022] Open
Abstract
Background Construction of high quality cDNA libraries from the usually low amounts of eukaryotic mRNA extracted from environmental samples is essential in functional metatranscriptomics for the selection of functional, full-length genes encoding proteins of interest. Many of the inserts in libraries constructed by standard methods are represented by truncated cDNAs due to premature stoppage of reverse transcriptase activity and preferential cloning of short cDNAs. Results We report here a simple and cost effective technique for preparation of sized eukaryotic cDNA libraries from as low as three microgram of total soil RNA dominated by ribosomal and bacterial RNA. cDNAs synthesized by a template switching approach were size-fractionated by two dimensional agarose gel electrophoresis prior to PCR amplification and cloning. Effective size selection was demonstrated by PCR amplification of conserved gene families specific of each size class. Libraries of more than one million independent inserts whose sizes ranged between one and four kb were thus produced. Up to 80% of the insert sequences were homologous to eukaryotic gene sequences present in public databases. Conclusions A simple and cost effective technique has been developed to construct sized eukaryotic cDNA libraries from environmental samples. This technique will facilitate expression cloning of environmental eukaryotic genes and contribute to a better understanding of basic biological and/or ecological processes carried out by eukaryotic microbial communities.
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Affiliation(s)
- Rajiv Kumar Yadav
- Ecologie Microbienne, UMR CNRS 5557, USC INRA 1364, Université Lyon 1, Université de Lyon, Villeurbanne, France.
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Álvarez M, Menéndez-Arias L. Temperature effects on the fidelity of a thermostable HIV-1 reverse transcriptase. FEBS J 2013; 281:342-51. [PMID: 24279450 DOI: 10.1111/febs.12605] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/04/2013] [Accepted: 11/01/2013] [Indexed: 11/30/2022]
Abstract
Transcriptomics and gene expression analysis are largely dependent of the availability of efficient thermostable reverse transcriptases (RTs). However, the intrinsic fidelity of DNA synthesis catalyzed by retroviral RTs is low. Reported error rates are in the range 1.2 × 10(-5)-6.7 × 10(-4), with oncoretroviral RTs being the most faithful enzymes. Wild-type HIV-1 group O (HIV-1O) RT is a thermostable polymerase that is able to synthesize cDNA at temperatures as high as 70 °C. At 37 °C, its error rate has been estimated at 5.8 × 10(-5) in M13mp2 lacZ-based forward mutation assays. However, at higher temperatures (e.g. 50 and 55 °C), the accuracy of HIV-1O RT is increased by approximately two- to five-fold. At 55 °C, the HIV-1O RT error rate (1.3 × 10(-5)) was similar to that shown by the AffinityScript (Agilent Technologies Inc., La Jolla, CA, USA) RT, a commercially available thermostable murine leukaemia virus RT. At higher temperatures, the increased accuracy of the HIV-1 enzyme results from a lower base substitution error rate, although it shows a higher tendency to introduce frameshifts. Kinetic studies carried out with model template-primers suggest minor differences in nucleotide discrimination, although, at higher temperatures, HIV-1O RT showed a reduced ability to extend mispaired template-primers.
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Affiliation(s)
- Mar Álvarez
- Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Spain
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18
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Barrioluengo V, Wang Y, Le Grice SFJ, Menéndez-Arias L. Intrinsic DNA synthesis fidelity of xenotropic murine leukemia virus-related virus reverse transcriptase. FEBS J 2012; 279:1433-44. [PMID: 22340433 DOI: 10.1111/j.1742-4658.2012.08532.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although recent reports have provided strong evidence to suggest that xenotropic murine leukemia virus-related virus (XMRV) is unlikely to be the causative agent of prostate cancer and chronic fatigue syndrome, this recombinant retrovirus can nonetheless infect human cells in vitro and induce a chronic infection in macaques. In the present study, we determined the accuracy of DNA synthesis of the reverse transcriptases (RTs) of XMRV and Moloney murine leukemia virus (MoMLV) using a combination of pre-steady-state kinetics of nucleotide incorporation and an M13mp2-based forward mutation assay. The results obtained were compared with those previously reported for the HIV type 1 BH10 strain (HIV-1(BH10)) RT. MoMLV and XMRV RTs were 13.9 and 110 times less efficient [as determined by the catalytic rate constant of the nucleotide incorporation reaction ((pol))/equilibrium constant (K(d))] than the HIV-1(BH10) RT in incorporating correct nucleotides. Misinsertion and mispair extension kinetic studies demonstrated that MoMLV RT was more accurate than the HIV-1(BH10) RT. In comparison with the MoMLV RT, the XMRV RT showed decreased mispair extension fidelity and was less faithful when misincorporating C or A opposite A. However, the XMRV RT showed stronger selectivity against G in misinsertion fidelity assays. Forward mutation assays revealed that XMRV and MoMLV RTs had similar accuracy of DNA-dependent DNA synthesis, but were > 13 times more faithful than the HIV-1(BH10) enzyme. The mutational spectra of XMRV and MoMLV RTs were similar in having a relatively higher proportion of frameshifts and transversions compared with the HIV-1(BH10) RT. However, the XMRV polymerase was less prone to introduce large deletions and one-nucleotide insertions.
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Affiliation(s)
- Verónica Barrioluengo
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Madrid, Spain
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Schmid D, Stolzlechner M, Sorgner A, Bentele C, Assinger A, Chiba P, Moeslinger T. An abundant, truncated human sulfonylurea receptor 1 splice variant has prodiabetic properties and impairs sulfonylurea action. Cell Mol Life Sci 2012; 69:129-48. [PMID: 21671119 PMCID: PMC11114697 DOI: 10.1007/s00018-011-0739-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 05/20/2011] [Accepted: 05/23/2011] [Indexed: 12/20/2022]
Abstract
An alternatively spliced form of human sulfonylurea receptor (SUR) 1 mRNA lacking exon 2 (SUR1Δ2) has been identified. The omission of exon 2 caused a frame shift and an immediate stop codon in exon 3 leading to translation of a 5.6-kDa peptide that comprises the N-terminal extracellular domain and the first transmembrane helix of SUR1. Based on a weak first splice acceptor site in the human SUR1 gene (ABCC8), RT-PCR revealed a concurrent expression of SUR1Δ2 and SUR1. The SUR1Δ2/(SUR1 + SUR1Δ2) mRNA ratio differed between tissues, and was lowest in pancreas (46%), highest in heart (88%) and negatively correlated with alternative splice factor/splicing factor 2 (ASF/SF2) expression. In COS-7 cells triple transfected with SUR1Δ2/SUR1/Kir6.2, the SUR1Δ2 peptide co-immunoprecipitated with Kir6.2, thereby displacing two of four SUR1 subunits on the cell surface. The ATP sensitivity of these hybrid ATP-sensitive potassium channels (K(ATP)) channels was reduced by about sixfold, as shown with single-channel recordings. RINm5f rat insulinoma cells, which genuinely express SUR1 but not SUR1Δ2, exhibited a strongly increased K(ATP) channel current upon transfection with SUR1Δ2. This led to inhibition of glucose-induced depolarization, calcium flux, insulin release and glibenclamide action. A non-mutagenic SNP on nucleotide position 333 (Pro69Pro) added another exonic splicing enhancer sequence detected by ASF/SF2, reduced relative abundance of SUR1Δ2 and slightly protected from non-insulin dependent diabetes in homozygotic individuals. Thus, SUR1Δ2 represents an endogenous K(ATP)-channel modulator with prodiabetic properties in islet cells. Its predominance in heart may explain why high-affinity sulfonylurea receptors are not found in human cardiac tissue.
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MESH Headings
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Alternative Splicing/physiology
- Animals
- COS Cells
- Calcium/metabolism
- Chlorocebus aethiops
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/physiopathology
- Exons/physiology
- Glyburide/pharmacology
- Humans
- Hypoglycemic Agents/pharmacology
- Insulin/metabolism
- Islets of Langerhans/metabolism
- KATP Channels/drug effects
- KATP Channels/metabolism
- Myocardium/metabolism
- Organ Specificity/genetics
- Pancreas/metabolism
- Polymorphism, Single Nucleotide
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Species Specificity
- Sulfonylurea Receptors
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Affiliation(s)
- Diethart Schmid
- Institute of Physiology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
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20
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Aggarwal S, Bradel-Tretheway B, Takimoto T, Dewhurst S, Kim B. Biochemical characterization of enzyme fidelity of influenza A virus RNA polymerase complex. PLoS One 2010; 5:e10372. [PMID: 20454455 PMCID: PMC2861597 DOI: 10.1371/journal.pone.0010372] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 04/07/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND It is widely accepted that the highly error prone replication process of influenza A virus (IAV), together with viral genome assortment, facilitates the efficient evolutionary capacity of IAV. Therefore, it has been logically assumed that the enzyme responsible for viral RNA replication process, influenza virus type A RNA polymerase (IAV Pol), is a highly error-prone polymerase which provides the genomic mutations necessary for viral evolution and host adaptation. Importantly, however, the actual enzyme fidelity of IAV RNA polymerase has never been characterized. PRINCIPAL FINDINGS Here we established new biochemical assay conditions that enabled us to assess both polymerase activity with physiological NTP pools and enzyme fidelity of IAV Pol. We report that IAV Pol displays highly active RNA-dependent RNA polymerase activity at unbiased physiological NTP substrate concentrations. With this robust enzyme activity, for the first time, we were able to compare the enzyme fidelity of IAV Pol complex with that of bacterial phage T7 RNA polymerase and the reverse transcriptases (RT) of human immunodeficiency virus (HIV-1) and murine leukemia virus (MuLV), which are known to be low and high fidelity enzymes, respectively. We observed that IAV Pol displayed significantly higher fidelity than HIV-1 RT and T7 RNA polymerase and equivalent or higher fidelity than MuLV RT. In addition, the IAV Pol complex showed increased fidelity at lower temperatures. Moreover, upon replacement of Mg(++) with Mn(++), IAV Pol displayed increased polymerase activity, but with significantly reduced processivity, and misincorporation was slightly elevated in the presence of Mn(++). Finally, when the IAV nucleoprotein (NP) was included in the reactions, the IAV Pol complex exhibited enhanced polymerase activity with increased fidelity. SIGNIFICANCE Our study indicates that IAV Pol is a high fidelity enzyme. We envision that the high fidelity nature of IAV Pol may be important to counter-balance the multiple rounds of IAV genome amplification per infection cycle, which provides IAV Pol with ample opportunities to generate and amplify genomic founder mutations, and thus achieve optimal viral mutagenesis for its evolution.
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Affiliation(s)
- Shilpa Aggarwal
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Birgit Bradel-Tretheway
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Toru Takimoto
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Stephen Dewhurst
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Baek Kim
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail:
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21
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Kennedy EM, Hergott C, Dewhurst S, Kim B. The mechanistic architecture of thermostable Pyrococcus furiosus family B DNA polymerase motif A and its interaction with the dNTP substrate. Biochemistry 2009; 48:11161-8. [PMID: 19817489 DOI: 10.1021/bi9010122] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Thermostable DNA polymerases isolated from archaeal organisms have not been completely characterized kinetically and require further study if we are to understand both their dNTP binding mechanism and their role within the organism. Here, we demonstrate that the thermostable family B DNA polymerase from Pyrococcus furiosus (Pfu Pol) contains sensitive determinants of both dNTP binding and replicational fidelity within the highly conserved motif A. Site-directed mutagenesis of the motif A SYLP region revealed that small shifts in side chain volume result in significant changes in the dNTP binding affinity, steady state kinetics, and fidelity of the enzyme. Mutants of Y410 show high fidelity in both misincorporation assays and forward mutation assays, but display a substantially higher K(m) than the wild type. In contrast, mutations of upstream residue L409 result in a drastically reduced affinity for the correct dNTP, a much higher efficiency of both misincorporation and mismatch extension, and substantially lower fidelity as demonstrated by a PCR-based forward mutation assay. The A408S mutant, however, displayed a significant increase in both dNTP binding affinity and fidelity. In summary, these data show that modulation of motif A can greatly shift both the steady and pre-steady state kinetics of the enzyme as well as the fidelity of Pfu Pol.
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Affiliation(s)
- Edward M Kennedy
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA
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22
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Increased Thermostability and Fidelity of DNA Synthesis of Wild-Type and Mutant HIV-1 Group O Reverse Transcriptases. J Mol Biol 2009; 392:872-84. [DOI: 10.1016/j.jmb.2009.07.081] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 07/24/2009] [Accepted: 07/28/2009] [Indexed: 11/18/2022]
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Paar M, Klein D, Salmons B, Günzburg WH, Renner M, Portsmouth D. Influence of vector design and host cell on the mechanism of recombination and emergence of mutant subpopulations of replicating retroviral vectors. BMC Mol Biol 2009; 10:8. [PMID: 19203366 PMCID: PMC2645402 DOI: 10.1186/1471-2199-10-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 02/09/2009] [Indexed: 12/22/2022] Open
Abstract
Background The recent advent of murine leukaemia virus (MLV)-based replication-competent retroviral (RCR) vector technology has provided exciting new tools for gene delivery, albeit the advances in vector efficiency which have been realized are also accompanied by a set of fresh challenges. The expression of additional transgene sequences, for example, increases the length of the viral genome, which can lead to reductions in replication efficiency and in turn to vector genome instability. This necessitates efforts to analyse the rate and mechanism of recombinant emergence during the replication of such vectors to provide data which should contribute to improvements in RCR vector design. Results In this study, we have performed detailed molecular analyses on packaged vector genomes and proviral DNA following propagation of MLV-based RCR vectors both in cell culture and in pre-formed subcutaneous tumours in vivo. The effects of strain of MLV, transgene position and host cell type on the rate of emergence of vector recombinants were quantitatively analysed by applying real-time PCR and real-time RT-PCR assays. Individual mutants were further characterized by PCR, and nucleotide sequence and structural motifs associated with these mutants were determined by sequencing. Our data indicate that virus strain, vector design and host cell influence the rate of emergence of predominating vector mutants, but not the underlying recombination mechanisms in vitro. In contrast, however, differences in the RNA secondary structural motifs associated with sequenced mutants emerging in cell culture and in solid tumours in vivo were observed. Conclusion Our data provide further evidence that MLV-based RCR vectors based on the Moloney strain of MLV and containing the transgene cassette in the 3' UTR region are superior to those based on Akv-MLV and/or containing the transgene cassette in the U3 region of the LTR. The observed discrepancies between the data obtained in solid tumours in vivo and our own and previously published data from infected cells in vitro demonstrates the importance of evaluating vectors designed for use in cancer gene therapy in vivo as well as in vitro.
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Affiliation(s)
- Matthias Paar
- Department of Pathobiology, Institute of Virology, University of Veterinary Medicine, Vienna, Austria.
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Arezi B, Hogrefe H. Novel mutations in Moloney Murine Leukemia Virus reverse transcriptase increase thermostability through tighter binding to template-primer. Nucleic Acids Res 2008; 37:473-81. [PMID: 19056821 PMCID: PMC2632894 DOI: 10.1093/nar/gkn952] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In an effort to increase the thermostability of Moloney Murine Leukemia Virus reverse transcriptase (MMLV RT), we screened random and site-saturation libraries for variants that show increased resistance to thermal inactivation. We discovered five mutations E69K, E302R, W313F, L435G and N454K that collectively increase the half-life of MMLV RT at 55°C from less than 5 min to ∼30 min in the presence of template-primer. In addition, these mutations alter the thermal profile by increasing specific activity of the pentuple mutant (M5) over a broad range of cDNA synthesis temperatures (25–70°C). We further show that M5 generates higher cDNA yields and exhibits better RT–PCR performance compared to wild-type RT when used at high temperature to amplify RNA targets containing secondary structure. Finally, we demonstrate that M5 exhibits tighter binding (lower Km) to template-primer, which likely protects against heat inactivation.
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Affiliation(s)
- Bahram Arezi
- Agilent Technologies, Stratagene Products Division, La Jolla, CA 92037, USA.
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25
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Nadai Y, Eyzaguirre LM, Constantine NT, Sill AM, Cleghorn F, Blattner WA, Carr JK. Protocol for nearly full-length sequencing of HIV-1 RNA from plasma. PLoS One 2008; 3:e1420. [PMID: 18183300 PMCID: PMC2170516 DOI: 10.1371/journal.pone.0001420] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 12/07/2007] [Indexed: 11/18/2022] Open
Abstract
Nearly full-length genome sequencing of HIV-1 using peripheral blood mononuclear cells (PBMC) DNA as a template for PCR is now a relatively routine laboratory procedure. However, this has not been the case when using virion RNA as the template and this has made full genome analysis of circulating viruses difficult. Therefore, a well-developed procedure for sequencing of full-length HIV-1 RNA directly from plasma was needed. Plasma from U.S. donors representing a range of viral loads (VL) was used to develop the assay. RNA was extracted from plasma and reverse-transcribed. Two or three overlapping regions were PCR amplified to cover the entire viral genome and sequenced for verification. The success of the procedure was sensitive to VL but was routinely successful for VL greater than 105 and the rate declined in proportion to the VL. While the two-amplicon strategy had an advantage of increasing the possibility of amplifying a single species of HIV-1, the three-amplicon strategy was more successful in amplifying samples with low viral loads. This protocol provides a useful tool for molecular analysis to understand the HIV epidemic and pathogenesis, as well as diagnosis, therapy and future vaccine strategies.
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Affiliation(s)
- Yuka Nadai
- Department of Epidemiology, Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States of America
| | - Lindsay M. Eyzaguirre
- Department of Epidemiology, Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States of America
| | - Niel T. Constantine
- Department of Epidemiology, Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States of America
| | - Anne M. Sill
- Department of Epidemiology, Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States of America
| | | | - William A. Blattner
- Department of Epidemiology, Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States of America
| | - Jean K. Carr
- Department of Epidemiology, Institute of Human Virology, University of Maryland, Baltimore, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail:
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Leparc GG, Mitra RD. A sensitive procedure to detect alternatively spliced mRNA in pooled-tissue samples. Nucleic Acids Res 2007; 35:e146. [PMID: 18000005 PMCID: PMC2175357 DOI: 10.1093/nar/gkm989] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
One important goal of genomics is to explore the extent of alternative splicing in the transcriptome and generate a comprehensive catalog of splice forms. New computational and experimental approaches have led to an increase in the number of predicted alternatively spliced transcripts; however, validation of these predictions has not kept pace. In this work, we systematically explore different methods for the validation of cassette exons predicted by computational methods or tiling microarrays. Our goal was to find a procedure that is cost effective, sensitive and specific. We examined three ways of priming the reverse transcription (RT) reaction—poly-dT priming, random priming and pooled exon-specific priming. We also examined two strategies for PCR amplification—flanking PCR, which uses primers that hybridize to the constitutive exons flanking the predicted exon, and a semi-nested PCR with a primer that targets the predicted exon. We found that the combination of RT using a pool of gene-specific primers followed by semi-nested PCR resulted in a significant increase in sensitivity over the most commonly used methodology (97% of the test set was detected versus 14%). Our method was also highly specific—no false positives were detected using a test set of true negatives. Finally, we demonstrate that this method is able to detect alternative exons with a high sensitivity from whole-organism RNA, allowing all tissues to be sampled in a single experiment. The protocol developed here is an accurate and cost-effective way to validate predictions of alternative splicing.
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Affiliation(s)
- Germán Gastón Leparc
- Department of Genetics and Center for Genome Sciences, Washington University in St Louis, 4444 Forest Park Parkway, Campus Box 8510, St Louis, MO 63108, USA
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Wang E, Panelli M, Marincola FM. Complementary techniques: RNA amplification for gene profiling analysis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 593:39-53. [PMID: 17265715 DOI: 10.1007/978-0-387-39978-2_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The study of clinical samples is often limited by the amount of material available. DNA and RNA can be amplified from small specimens and, therefore, used for high-throughput analyses. While precise estimates of the level of DNA concentration in a given specimen is rarely studied (with the exception of relatively crude analyses of gene amplification or loss in cancer specimens), it is critical to know the proportional expression of various RNA transcripts since this proportion governs cell function by modulating the expression of various proteins. In addition, accurate estimates of relative RNA expression in biological conditions portray the reaction of cells to environmental stimuli shedding light on the characteristics of the microenvironment associated with particular physiologic or pathologic conditions. For this reason, the development of technologies for high fidelity messenger RNA amplification have been focused of extreme interest in the past decade with specific aim not only of increasing the abundance of RNA available to study but to accurately maintain the proportionality of expression of various RNA species among each other within a given specimen. This chapter will discuss various approaches to proportional RNA amplification focusing on amplification of the whole transcriptome (all transcripts in a given samples) rather than individual genes. These methods are suitable for high-throughput transcriptional profiling studies.
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28
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Gosselink JV, Hayashi S, Chau E, Cooper J, Elliott WM, Hogg JC. Evaluation of small sample cDNA amplification for microdissected airway expression profiling in COPD. COPD 2007; 4:91-105. [PMID: 17530502 DOI: 10.1080/15412550701246427] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Small airway obstruction and emphysematous destruction account for the airflow limitation that defines chronic obstructive pulmonary disease (COPD). While laser capture microdissection (LCM) allows gene expression studies in small airways separately from the surrounding parenchyma, tissue size limits the number of genes examined. The present study evaluates the Clontech SMART amplification to test the hypothesis that this amplification provides RNA in sufficient quantity and quality to evaluate large numbers of genes in airways < 2 mm diameter obtained by LCM. Commercial reference RNA was amplified 200-fold and the expression levels of 51 genes relative to the unamplified RNA had a correlation coefficient of 0.84. For two pairs of RNA preparations (commercial placenta versus commercial lung; lung sections prepared for LCM from GOLD 0 (at risk for COPD) versus GOLD 2 (moderate disease) patients linear regression of Delta Ct's (delta cycle thresholds) of unamplified versus amplified RNA gave correlation coefficients of R = 0.95. In RNA from microdissected small airways, expression patterns in all GOLD classes of COPD severity were very similar between unamplified and amplified RNA. We conclude that SMART amplification provides cDNA sufficient for studying large numbers of genes even in laser-captured small airways and this cDNA maintains the relative expression found in corresponding unamplified RNAs.
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Affiliation(s)
- John V Gosselink
- St. Paul's Hospital, The James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research and University of British Columbia, Vancouver, British Columbia.
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29
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Jamburuthugoda VK, Chugh P, Kim B. Modification of human immunodeficiency virus type 1 reverse transcriptase to target cells with elevated cellular dNTP concentrations. J Biol Chem 2006; 281:13388-13395. [PMID: 16497663 DOI: 10.1074/jbc.m600291200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retroviruses and DNA viruses utilize cellular dNTPs as substrates for their DNA polymerases during viral replication in infected cells. However, because of S phase-dependent dNTP biosynthesis, the availability of cellular dNTPs significantly varies among cell types (e.g. dividing versus nondividing cells and normal versus tumor cells). Here we tested whether alterations in the dNTP utilization efficiency and dNTP binding affinity of viral DNA polymerases can switch viral infection specificity to cell types with different dNTP concentrations. We employed an HIV-1 reverse transcriptase (RT) mutant (Q151N), which is catalytically active only at high dNTP concentrations because of its reduced dNTP binding affinity. Indeed, the modified HIV-1 vector harboring the Q151N mutant RT preferentially transduced tumor cells containing higher cellular dNTP concentrations than primary cells (e.g. human lung fibroblasts (HLFs) and human keratinocytes). Although the wild type HIV-1 vector transduced both HLFs and tumor cells, the Q151N vector failed to transduce HLFs and keratinocytes but efficiently transduced tumor cells. Pretreatment of HLFs with deoxynucleosides, which increase cellular dNTP pools, enabled the mutant vector to transduce HLFs, suggesting that the transduction failure of the RT mutant vector to primary cells is because of inefficient reverse transcription in low cellular dNTP environments. We also observed that the Q151N vector expressing herpes simplex virus-thymidine kinase renders tumor cells sensitive to gancyclovir. This study validates a novel strategy in which modifications of viral DNA polymerases in various vector systems allow the delivery of target genes exclusively to tumor cells exploiting elevated cellular dNTP concentration as a tumor cell-specific host factor.
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Affiliation(s)
- Varuni K Jamburuthugoda
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642
| | - Pauline Chugh
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642
| | - Baek Kim
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642.
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30
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Wang E. RNA amplification for successful gene profiling analysis. J Transl Med 2005; 3:28. [PMID: 16042807 PMCID: PMC1201175 DOI: 10.1186/1479-5876-3-28] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 07/25/2005] [Indexed: 11/10/2022] Open
Abstract
The study of clinical samples is often limited by the amount of material available to study. While proteins cannot be multiplied in their natural form, DNA and RNA can be amplified from small specimens and used for high-throughput analyses. Therefore, genetic studies offer the best opportunity to screen for novel insights of human pathology when little material is available. Precise estimates of DNA copy numbers in a given specimen are necessary. However, most studies investigate static variables such as the genetic background of patients or mutations within pathological specimens without a need to assess proportionality of expression among different genes throughout the genome. Comparative genomic hybridization of DNA samples represents a crude exception to this rule since genomic amplification or deletion is compared among different specimens directly. For gene expression analysis, however, it is critical to accurately estimate the proportional expression of distinct RNA transcripts since such proportions directly govern cell function by modulating protein expression. Furthermore, comparative estimates of relative RNA expression at different time points portray the response of cells to environmental stimuli, indirectly informing about broader biological events affecting a particular tissue in physiological or pathological conditions. This cognitive reaction of cells is similar to the detection of electroencephalographic patterns which inform about the status of the brain in response to external stimuli. As our need to understand human pathophysiology at the global level increases, the development and refinement of technologies for high fidelity messenger RNA amplification have become the focus of increasing interest during the past decade. The need to increase the abundance of RNA has been met not only for gene specific amplification, but, most importantly for global transcriptome wide, unbiased amplification. Now gene-specific, unbiased transcriptome wide amplification accurately maintains proportionality among all RNA species within a given specimen. This allows the utilization of clinical material obtained with minimally invasive methods such as fine needle aspirates (FNA) or cytological washings for high throughput functional genomics studies. This review provides a comprehensive and updated discussion of the literature in the subject and critically discusses the main approaches, the pitfalls and provides practical suggestions for successful unbiased amplification of the whole transcriptome in clinical samples.
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Affiliation(s)
- Ena Wang
- Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
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31
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Operario DJ, Reynolds HM, Kim B. Comparison of DNA polymerase activities between recombinant feline immunodeficiency and leukemia virus reverse transcriptases. Virology 2005; 335:106-21. [PMID: 15823610 DOI: 10.1016/j.virol.2005.02.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2004] [Revised: 12/22/2004] [Accepted: 02/11/2005] [Indexed: 11/29/2022]
Abstract
In this study, we present enzymatic differences found between recombinant RTs derived from feline leukemia virus and feline immunodeficiency virus. Firstly, FIV RT showed low steady state K(m) values for dNTPs compared to FeLV RT. Consistent with this, FIV RT synthesized DNA more efficiently than FeLV RT at low dNTP concentrations. We observed similar concentration-dependent activity differences between other lentiviral (HIV-1 and SIV) and non-lentiviral (MuLV and AMV) RTs. Second, FeLV RT showed less efficient misincorporation with biased dNTP pools and mismatch primer extension capabilities, compared to FIV RT. In M13mp2 lacZalpha forward mutation assays, FeLV RT displayed approximately 11-fold higher fidelity than FIV RT. Finally, FeLV RT was less sensitive to 3TCTP and ddATP than FIV RT. This study represents the comprehensive enzymatic characterization of RTs from a lentivirus and a non-lentivirus retrovirus from the same host species. The data presented here support enzymatic divergences seen among retroviral RTs.
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Affiliation(s)
- Darwin J Operario
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Avenue, Box 672, Rochester, NY 14642, USA
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32
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Lee J, Hever A, Willhite D, Zlotnik A, Hevezi P. Effects of RNA degradation on gene expression analysis of human postmortem tissues. FASEB J 2005; 19:1356-8. [PMID: 15955843 DOI: 10.1096/fj.04-3552fje] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Affymetrix GeneChip platform was used to build a gene expression database of the normal human body. Postmortem human tissues represent a valuable source of biological materials for this type of study, but their use entails some delays before harvesting such tissues. We first evaluated the RNA quality obtained from tissues obtained 3-5 h postmortem and found variations that were both tissue and donor-dependent. RNAs extracted from brain regions were of higher quality than those obtained from the gut, while the cause of death was a significant factor in donor-dependent differences. To avoid these variables, we used rat duodenum to determine the effects of RNA degradation on the analysis of gene expression. Surprisingly, even samples exhibiting significant RNA degradation yielded robust gene expression results, comparable to those obtained using intact samples at a certain signal intensity cutoff. We extended these findings to our human expression database and obtained similar results, indicating that the Affymetrix platform, which is biased to the 3' end of transcripts for detection, can tolerate significant RNA degradation, while still yielding high quality expression data. Our resulting body index expression database is a valuable research tool. As examples of potential uses, we report novel expression sites for four potential therapeutic targets--CCL27, GPR22, GPR113 and GPR128--and as well as a set of thymus-specific genes, including three not previously associated with the thymus.
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Affiliation(s)
- Jerry Lee
- Department of Molecular Medicine, Neurocrine Biosciences Inc., San Diego, California, USA
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33
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Vellore J, Moretz SE, Lampson BC. A group II intron-type open reading frame from the thermophile Bacillus (Geobacillus) stearothermophilus encodes a heat-stable reverse transcriptase. Appl Environ Microbiol 2005; 70:7140-7. [PMID: 15574910 PMCID: PMC535183 DOI: 10.1128/aem.70.12.7140-7147.2004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The production of a stable cDNA copy of an unstable RNA molecule by reverse transcription is a widely used and essential technology for many important applications, such as the construction of gene libraries, production of DNA probes, and analysis of gene expression by reverse transcriptase PCR (RT-PCR). However, the synthesis of full-length cDNAs is frequently inefficient, because the RT commonly used often produces truncated cDNAs. Synthesizing cDNA at higher temperatures, on the other hand, can provide a number of improvements. These include increasing the length of cDNA product, greater accuracy, and greater specificity during reverse transcription. Thus, an RT that remains stable and active at hot temperatures may produce better-quality cDNAs and improve the yield of full-length cDNAs. Described here is the discovery of a gene, designated trt, from the genome of the thermophilic bacterium Bacillus (Geobacillus) stearothermophilus strain 10. The gene codes for an open reading frame (ORF) similar to the ORFs encoded by group II introns found in bacteria. The gene was cloned and overexpressed in Escherichia coli, and its protein product was partially purified. Like the host organism, the Trt protein is a heat-stable protein with RT activity and can reverse transcribe RNA at temperatures as high as 75 degrees C.
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Affiliation(s)
- Jaishree Vellore
- Department of Health Sciences, East Tennessee State University, Johnson City, TN 37614, USA
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Skasko M, Weiss KK, Reynolds HM, Jamburuthugoda V, Lee K, Kim B. Mechanistic differences in RNA-dependent DNA polymerization and fidelity between murine leukemia virus and HIV-1 reverse transcriptases. J Biol Chem 2005; 280:12190-200. [PMID: 15644314 PMCID: PMC1752212 DOI: 10.1074/jbc.m412859200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We compared the mechanistic and kinetic properties of murine leukemia virus (MuLV) and human immunodeficiency virus type 1 (HIV-1) reverse transcriptases (RTs) during RNA-dependent DNA polymerization and mutation synthesis using pre-steady-state kinetic analysis. First, MuLV RT showed 6.5-121.6-fold lower binding affinity (K(d)) to deoxynucleotide triphosphate (dNTP) substrates than HIV-1 RT, although the two RTs have similar incorporation rates (k(pol)). Second, compared with HIV-1 RT, MuLV RT showed dramatic reduction during multiple dNTP incorporations at low dNTP concentrations. Presumably, due to its low dNTP binding affinity, the dNTP binding step becomes rate-limiting in the multiple rounds of the dNTP incorporation by MuLV RT, especially at low dNTP concentrations. Third, similar fold differences between MuLV and HIV-1 RTs in the K(d) and k(pol) values to correct and incorrect dNTPs were observed. This indicates that these two RT proteins have similar misinsertion fidelities. Fourth, these two RT proteins have different mechanistic capabilities regarding mismatch extension. MuLV RT has a 3.1-fold lower mismatch extension fidelity, compared with HIV-1 RT. Finally, MuLV RT has a 3.8-fold lower binding affinity to mismatched template/primer (T/P) substrate compared with HIV-1 RT. Our data suggest that the active site of MuLV RT has an intrinsically low dNTP binding affinity, compared with HIV-1 RT. In addition, instead of the misinsertion step, the mismatch extension step, which varies between MuLV and HIV-1 RTs, contributes to their fidelity differences. The implications of these kinetic differences between MuLV and HIV-1 RTs on viral cell type specificity and mutagenesis are discussed.
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Affiliation(s)
- Mark Skasko
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York 14642, USA
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35
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Kenzelmann M, Klären R, Hergenhahn M, Bonrouhi M, Gröne HJ, Schmid W, Schütz G. High-accuracy amplification of nanogram total RNA amounts for gene profiling. Genomics 2004; 83:550-8. [PMID: 15028277 DOI: 10.1016/j.ygeno.2003.09.026] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Accepted: 09/16/2003] [Indexed: 11/26/2022]
Abstract
Microarray-based gene profiling of laser-assisted microdissected tissues or clinical biopsies is still a challenge since the amount of total RNA in such samples is limited and amplification of RNA is mandatory. Representative amplification of mRNA is highly dependent on the reverse transcription reaction, which is error prone, and on the number of amplification cycles. To improve the accuracy of RNA amplification, we optimized, combined, and tested different amplification strategies for Affymetrix oligonucleotide array hybridization. We demonstrate that different protocols differ significantly in quality of mRNA amplification. To demonstrate the accuracy and reproducibility of our optimized protocol in a clinical setting, we analyzed total RNAs from laser-assisted, microdissected cells of human prostate tissues. On the basis of these results, we recommend a standard reverse transcription reaction for small-sample-transcriptome profiling experiments as part of the Minimal Information about a Microarray Experiment (MIAME) set of standards.
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Affiliation(s)
- Marc Kenzelmann
- Division of Molecular Biology of the Cell I, Deutsches Krebsforschungszentrum Heidelberg, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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36
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Schumacher JA, Jenson SD, Elenitoba-Johnson KSJ, Lim MS. Utility of linearly amplified RNA for RT-PCR detection of chromosomal translocations: validation using the t(2;5)(p23;q35) NPM-ALK chromosomal translocation. J Mol Diagn 2004; 6:16-21. [PMID: 14736822 PMCID: PMC1867461 DOI: 10.1016/s1525-1578(10)60486-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The requirement for sufficient quantities of starting RNA has limited the ability to evaluate multiple transcripts using reverse transcriptase-polymerase chain reaction (RT-PCR). In this study, we demonstrate the utility of linear RNA amplification for RT-PCR analysis of multiple gene transcripts including a chromosomal translocation, using the t(2;5)(p23;q35) as a model. RNA from the t(2;5)-positive cell line, SU-DHL-1, and the t(2;5)-negative cell line, HUT-78, was extracted and exposed to two rounds of linear amplification. RT-PCR using cDNA from the resultant amplified (a) RNA and total RNA resulted in the 177 bp NPM-ALK fusion gene product from the SU-DHL-1 cell line, but not from aRNA or total RNA from the HUT-78 cell line. DNA sequencing of the RT-PCR products from total and aRNA of SU-DHL-1 cells demonstrated identical sequences corresponding to the NPM-ALK fusion gene. Evaluation of 25 snap-frozen tissue samples, including eight NPM-ALK-positive ALCLs demonstrated 100% concordance of t(2;5) detection between cDNA from total RNA and that from aRNA. Our results show that linear amplification of RNA can enhance starting RNA greater than 200-fold and can be used for rapid and specific detection of multiplex gene expression from a variety of sources. This method can generate a renewable archive of representative cDNA, which can be used for retrospective screening of stored samples as well as positive controls for the clinical molecular diagnostic laboratory.
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Affiliation(s)
- Jonathan A Schumacher
- Associated Regional and University Pathologists Institute for Clinical and Experimental Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA
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37
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Diamond TL, Roshal M, Jamburuthugoda VK, Reynolds HM, Merriam AR, Lee KY, Balakrishnan M, Bambara RA, Planelles V, Dewhurst S, Kim B. Macrophage tropism of HIV-1 depends on efficient cellular dNTP utilization by reverse transcriptase. J Biol Chem 2004; 279:51545-53. [PMID: 15452123 PMCID: PMC1351161 DOI: 10.1074/jbc.m408573200] [Citation(s) in RCA: 236] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retroviruses utilize cellular dNTPs to perform proviral DNA synthesis in infected host cells. Unlike oncoretroviruses, which replicate in dividing cells, lentiviruses, such as human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus, are capable of efficiently replicating in non-dividing cells (terminally differentiated macrophages) as well as dividing cells (i.e. activated CD4+ T cells). In general, non-dividing cells are likely to have low cellular dNTP content compared with dividing cells. Here, by employing a novel assay for cellular dNTP content, we determined the dNTP concentrations in two HIV-1 target cells, macrophages and activated CD4+ T cells. We found that human macrophages contained 130-250-fold lower dNTP concentrations than activated human CD4+ T cells. Biochemical analysis revealed that, unlike oncoretroviral reverse transcriptases (RTs), lentiviral RTs efficiently synthesize DNA even in the presence of the low dNTP concentrations equivalent to those found in macrophages. In keeping with this observation, HIV-1 vectors containing mutant HIV-1 RTs, which kinetically mimic oncoretroviral RTs, failed to transduce human macrophages despite retaining normal infectivity for activated CD4+ T cells and other dividing cells. These results suggest that the ability of HIV-1 to infect macrophages, which is essential to establishing the early pathogenesis of HIV-1 infection, depends, at least in part, on enzymatic adaptation of HIV-1 RT to efficiently catalyze DNA synthesis in limited cellular dNTP substrate environments.
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Affiliation(s)
| | | | | | | | | | - Kwi Y. Lee
- Department of Microbiology and Immunology
| | | | - Robert A. Bambara
- Department of Biochemistry and Biophysics, and
- Cancer Center, University of Rochester Medical Center, 601 Elmwood Avenue Box 672, Rochester, New York 14642
| | - Vicente Planelles
- Department of Pathology, University of Utah School of Medicine, 30 N. 1900 East, SOM C210, Salt Lake City, UT 84132
| | - Stephen Dewhurst
- Department of Microbiology and Immunology
- Cancer Center, University of Rochester Medical Center, 601 Elmwood Avenue Box 672, Rochester, New York 14642
| | - Baek Kim
- Department of Microbiology and Immunology
- *Corresponding author Baek Kim, Ph.D., Department of Microbiology and Immunology, University of Rochester, 601 Elmwood Avenue Box 672, Rochester, NY 14642, Tel: (585) 275-6916, Fax: (585) 473-9573,
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38
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Grønbaek K, Ralfkiaer E, Kalla J, Skovgaard GL, Guldberg P. Infrequent somatic Fas mutations but no evidence of Bcl10 mutations or t(11;18) in primary cutaneous MALT-type lymphoma. J Pathol 2003; 201:134-40. [PMID: 12950026 DOI: 10.1002/path.1426] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genetic alterations that allow tumour cells to evade apoptosis have recently been identified as key features of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue type (MALT-type lymphoma). The t(11;18), which produces the putative anti-apoptotic fusion protein API2-MALT1, has been identified in a large proportion of extracutaneous MALT-type lymphomas and a smaller fraction of tumours harbour mutations that inactivate the pro-apoptotic functions of Fas and Bcl10. The present study has examined the status of these genes in 19 primary cutaneous B-cell lymphomas (PCBCLs), 12 of which were MALT-type lymphomas according to the WHO classification. None of the 19 PCBCLs carried the t(11;18) and tumour-specific Bcl10 alterations were not identified at the genomic level or at the mRNA level. Somatic Fas mutations causing truncation of the Fas receptor were identified in two MALT-type lymphomas. Both patients with Fas mutant PCBCL exhibited benign conditions of dysregulated lymphoproliferation. One had autoimmune diabetes and rheumatoid arthritis and the other had a 25-year history of recurrent cutaneous pseudo-lymphomas. It is suggested that Fas mutation permits the survival and hence the accumulation of autoreactive B cells. This expansion of autoreactive B cells is analogous to the expansion of B cells chronically stimulated by exogenous antigens in the development of MALT-type lymphoma.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adult
- Aged
- B-Cell CLL-Lymphoma 10 Protein
- Carrier Proteins/genetics
- Chromosomes, Human, Pair 11/genetics
- Chromosomes, Human, Pair 18/genetics
- DNA Mutational Analysis
- DNA, Neoplasm/genetics
- Female
- Gene Rearrangement
- Humans
- Lymphoma, B-Cell, Marginal Zone/genetics
- Male
- Middle Aged
- Mutation
- Neoplasm Proteins/genetics
- Oncogene Proteins, Fusion/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Skin Neoplasms/genetics
- Translocation, Genetic
- fas Receptor/genetics
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Affiliation(s)
- Kirsten Grønbaek
- Institute of Cancer Biology, The Danish Cancer Society, Copenhagen, Denmark.
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39
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Xiao W, Park CK, Park JY, Lee JH, Kim HS, Cho YG, Kim CJ, Ahn YM, Lee JH, Song YH, Lee SH, Yoo NJ, Lee JY, Park WS. Genetic alterations of the HCCS1 gene in Korean hepatocellular carcinoma. APMIS 2003; 111:465-73. [PMID: 12780520 DOI: 10.1034/j.1600-0463.2003.1110403.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We analyzed the gene mutations and loss of heterozygosity (LOH) of the HCCS1 gene using intragenic polymorphic markers in a series of 88 primary HCCs. We found two sequence variations at exon 5 and 14 in both normal and tumor DNAs of case 50 and 51, respectively. The variation in case 50 led to a reading frameshift and a premature stop (TGA) at codon 125 and case 51 showed amino acid change at codon 448 (Val-->Ala, GTG-->GCG). Interestingly, these variations were not found in peripheral lymphocytes of 69 normal individuals and 227 cancer patients (86 HCC, 75 unselected gastric cancer, and 66 breast cancer), suggesting that these two variations are mutation, not polymorphism. In addition, we found 14 novel intragenic polymorphic sites in the HCCS1 gene. Thirty-two (47%) of sixty-eight informative cases showed allelic loss at at least one or more intragenic polymorphic sites, but there was no significant relationship between the frequency of LOH and clinicopathologic parameters. These results suggest that mutation of the HCCS1 gene might not be a main inactivation mechanism in the development of Korean HCC and that the HCCS1 gene might be involved in acceleration of the tumorigenic process in Korean HCC.
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Affiliation(s)
- Wenhua Xiao
- Department of Pathology, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-gu, Seoul, Korea
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Menéndez-Arias L. Molecular basis of fidelity of DNA synthesis and nucleotide specificity of retroviral reverse transcriptases. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2003; 71:91-147. [PMID: 12102562 DOI: 10.1016/s0079-6603(02)71042-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Reverse transcription involves the conversion of viral genomic RNAinto proviral double-stranded DNA that integrates into the host cell genome. Cellular DNA polymerases replicate the integrated viral DNA and RNA polymerase II transcribes the proviral DNA into RNA genomes that are packaged into virions. Although mutations can be introduced at any of these replication steps, reverse transcriptase (RT) errors play a major role in retroviral mutation. This review summarizes our current knowledge on fidelity of reverse transcriptases. Estimates of retroviral mutation rates or fidelity of retroviral RTs are discussed in the context of the different techniques used for this purpose (i.e., retroviral vectors replicated in culture, misinsertion and mispair extension fidelity assay, etc.). In vitro fidelity assays provide information on the RT's accuracy during the elongation reaction of DNA synthesis. In addition, other steps such as initiation of reverse transcription, or strand transfer, and factors including viral proteins such as Vpr [in the case of the human immunodeficiency virus type 1 (HIV-1)] have been shown to influence fidelity. A comprehensive description of the effect of amino acid substitutions on the fidelity of HIV-1 RT is presented. Published data point to certain dNTP-binding residues, as well as to various amino acids involved in interactions with the template or the primer strand, and to residues in the minor groove-binding track as major components of the fidelity center of retroviral RTs. Implications of these studies include the design of novel therapeutic strategies leading to virus extinction, by increasing the viral mutation rate beyond a tolerable threshold.
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Affiliation(s)
- Luis Menéndez-Arias
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Spain
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41
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Bibillo A, Eickbush TH. High processivity of the reverse transcriptase from a non-long terminal repeat retrotransposon. J Biol Chem 2002; 277:34836-45. [PMID: 12101182 DOI: 10.1074/jbc.m204345200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
R2 is a retrotransposable element that specifically inserts into the 28 S rRNA genes of arthropods. The element encodes a single protein with endonuclease activity that cleaves the 28 S gene target site and reverse transcriptase (RT) activity that uses the cleaved DNA to prime reverse transcription. Here we compare various properties of the R2 RT activity with those of the well characterized retroviral RT, avian myeloblastosis virus (AMV). In processivity assays using heterogeneous RNA templates, R2 RT can synthesize cDNA over twice the length of that synthesized by AMV RT and can synthesize cDNA over 4 times longer than AMV RT in assays with poly(rA) templates. The higher processivity of R2 RT compared with retroviral RTs is a result of the slower rate of dissociation of the enzyme from RNA templates. The elongation rates of the two enzymes are similar. Finally, a highly distinct property of the R2 RT, compared with retroviral enzymes, is its ability to displace RNA strands annealed to RNA templates during cDNA synthesis. We suggest that both the higher processivity and displacement properties of R2 RT compared with retroviral RT result from the greater affinity of the R2 protein for the RNA template upstream of its active site.
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Affiliation(s)
- Arkadiusz Bibillo
- Department of Biology, University of Rochester, Rochester, New York 14627-0211, USA
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42
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Pi X, Voogt JL, Grattan DR. Detection of prolactin receptor mRNA in the corpus striatum and substantia nigra of the rat. J Neurosci Res 2002; 67:551-8. [PMID: 11835322 DOI: 10.1002/jnr.10147] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The observation of prolactin modulation of the nigrostriatal dopaminergic system suggests the expression of prolactin receptor in the corpus striatum or substantia nigra. The present study investigated expression of prolactin receptor mRNA in tissues microdissected from the corpus striatum and substantia nigra of the rat. By using reverse transcription PCR combined with Southern hybridization, the long form of prolactin receptor mRNA was detected in the substantia nigra, caudate putamen, globus pallidus, and ventral pallidum in ovariectomized rats, whereas the short form was not detectable in any of these areas. Estrogen had no effect on expression of the long-form mRNA in the substantia nigra and corpus striatum. By using the RNase protection assay, the expression of both short and long forms of prolactin receptor mRNA was observed in the corpus striatum in ovariectomized rats. Again, levels of expression were not significantly altered by estrogen treatment. Both forms of prolactin receptor mRNA were clearly expressed in the choroid plexus and were up-regulated by estrogen treatment. The expression of both forms of prolactin receptor mRNA in nigrostriatal areas may help to support the hypothesis that prolactin has direct actions on these brain regions.
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Affiliation(s)
- Xiujun Pi
- Department of Molecular and Integrative Physiology, Kansas University Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7401, USA
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