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Noe Gonzalez M, Blears D, Svejstrup JQ. Causes and consequences of RNA polymerase II stalling during transcript elongation. Nat Rev Mol Cell Biol 2021; 22:3-21. [PMID: 33208928 DOI: 10.1038/s41580-020-00308-8] [Citation(s) in RCA: 104] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2020] [Indexed: 02/07/2023]
Abstract
The journey of RNA polymerase II (Pol II) as it transcribes a gene is anything but a smooth ride. Transcript elongation is discontinuous and can be perturbed by intrinsic regulatory barriers, such as promoter-proximal pausing, nucleosomes, RNA secondary structures and the underlying DNA sequence. More substantial blocking of Pol II translocation can be caused by other physiological circumstances and extrinsic obstacles, including other transcribing polymerases, the replication machinery and several types of DNA damage, such as bulky lesions and DNA double-strand breaks. Although numerous different obstacles cause Pol II stalling or arrest, the cell somehow distinguishes between them and invokes different mechanisms to resolve each roadblock. Resolution of Pol II blocking can be as straightforward as temporary backtracking and transcription elongation factor S-II (TFIIS)-dependent RNA cleavage, or as drastic as premature transcription termination or degradation of polyubiquitylated Pol II and its associated nascent RNA. In this Review, we discuss the current knowledge of how these different Pol II stalling contexts are distinguished by the cell, how they overlap with each other, how they are resolved and how, when unresolved, they can cause genome instability.
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Affiliation(s)
- Melvin Noe Gonzalez
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, London, UK
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Daniel Blears
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, London, UK
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, London, UK.
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.
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McLaughlin G, Baumann MH, Kavanagh PV, Morris N, Power JD, Dowling G, Twamley B, O’Brien J, Hessman G, Westphal F, Walther D, Brandt SD. Synthesis, analytical characterization, and monoamine transporter activity of the new psychoactive substance 4-methylphenmetrazine (4-MPM), with differentiation from its ortho- and meta- positional isomers. Drug Test Anal 2018; 10:1404-1416. [PMID: 29673128 PMCID: PMC7316143 DOI: 10.1002/dta.2396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 04/12/2018] [Accepted: 04/13/2018] [Indexed: 12/21/2022]
Abstract
The availability of new psychoactive substances (NPS) on the recreational drug market continues to create challenges for scientists in the forensic, clinical and toxicology fields. Phenmetrazine (3-methyl-2-phenylmorpholine) and an array of its analogs form a class of psychostimulants that are well documented in the patent and scientific literature. The present study reports on two phenmetrazine analogs that have been encountered on the NPS market following the introduction of 3-fluorophenmetrazine (3-FPM), namely 4-methylphenmetrazine (4-MPM), and 3-methylphenmetrazine (3-MPM). This study describes the syntheses, analytical characterization, and pharmacological evaluation of the positional isomers of MPM. Analytical characterizations employed various chromatographic, spectroscopic, and mass spectrometric platforms. Pharmacological studies were conducted to assess whether MPM isomers might display stimulant-like effects similar to the parent compound phenmetrazine. The isomers were tested for their ability to inhibit uptake or stimulate release of tritiated substrates at dopamine, norepinephrine and serotonin transporters using in vitro transporter assays in rat brain synaptosomes. The analytical characterization of three vendor samples revealed the presence of 4-MPM in two of the samples and 3-MPM in the third sample, which agreed with the product label. The pharmacological findings suggest that 2-MPM and 3-MPM will exhibit stimulant properties similar to the parent compound phenmetrazine, whereas 4-MPM may display entactogen properties more similar to 3,4-methylenedioxymethamphetamine (MDMA). The combination of test purchases, analytical characterization, targeted organic synthesis, and pharmacological evaluation of NPS and their isomers is an effective approach for the provision of data on these substances as they emerge in the marketplace.
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Affiliation(s)
- Gavin McLaughlin
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James’s Hospital, James’s Street, Dublin 8, D08W9RT, Ireland
- Forensic Science Ireland, Garda Headquarters, Phoenix Park, Dublin 8, D08HN3X, Ireland
| | - Michael H. Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Suite 4400, Baltimore, MD 21224, USA
| | - Pierce V. Kavanagh
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James’s Hospital, James’s Street, Dublin 8, D08W9RT, Ireland
| | - Noreen Morris
- Department of Life & Physical Sciences, Faculty of Science and Health, Athlone Institute of Technology, Dublin Road, Athlone, Co. Westmeath, N37HD68, Ireland
| | - John D. Power
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James’s Hospital, James’s Street, Dublin 8, D08W9RT, Ireland
- Forensic Science Ireland, Garda Headquarters, Phoenix Park, Dublin 8, D08HN3X, Ireland
| | - Geraldine Dowling
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James’s Hospital, James’s Street, Dublin 8, D08W9RT, Ireland
- Department of Life Sciences, School of Science, Sligo Institute of Technology, Ash Lane, Sligo, F91YW50, Ireland
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, College Green, Dublin 2, D02EV57, Ireland
| | - John O’Brien
- School of Chemistry, Trinity College Dublin, College Green, Dublin 2, D02EV57, Ireland
| | - Gary Hessman
- School of Chemistry, Trinity College Dublin, College Green, Dublin 2, D02EV57, Ireland
| | - Folker Westphal
- State Bureau of Criminal Investigation Schleswig-Holstein, Section Narcotics/Toxicology, Mühlenweg 166, D-24116 Kiel, Germany
| | - Donna Walther
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Suite 4400, Baltimore, MD 21224, USA
| | - Simon D. Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
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McLaughlin G, Morris N, Kavanagh PV, Dowling G, Power JD, Twamley B, O'Brien J, Talbot B, Sitte HH, Brandt SD. Test purchase, synthesis and characterization of 3-fluorophenmetrazine (3-FPM) and differentiation from its ortho- and para-substituted isomers. Drug Test Anal 2016; 9:369-377. [PMID: 26810957 DOI: 10.1002/dta.1945] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 11/09/2022]
Abstract
The knowledge captured in patent and scientific research literature stimulates new ideas and fosters new drug development efforts. Manufacturers and entrepreneurs dedicated to the sale of 'research chemicals' and/or new psychoactive substances (NPS) also make use of access to information to identify, prepare, and launch a range of new substances. One of the most recent compounds to appear on the NPS market is the phenmetrazine analog 3-fluorophenmetrazine (3-FPM) which represents one of many phenylmorpholines designed to explore treatment options in areas such as obesity and drug dependence. The anorectic drug analogs phenmetrazine and phendimetrazine, used as prescription medicines before they were withdrawn, feature amphetamine-like properties associated with monoamine release. Available data on 3-FPM suggest that the effects might show mechanistic overlaps. This study describes the synthesis and extensive analytical characterization of 3-FPM and its differentiation from synthesized ortho- and para- substituted isomers, 2-FPM and 4-FPM, respectively. This study was triggered by the purchase of five powdered samples advertised as 3-FPM by five different Internet vendors based in the United Kingdom. The analytical data obtained for the vendor samples were consistent with the synthesized 3-FPM standard and differentiation between all three isomers was possible. The presence of positional isomers and the absence of suitable reference material can cause difficulties in the day-to-day operation of forensic work and given the rate at which many of the newly emerging NPS appear on the market, a comprehensive approach is needed when attempting to decipher the identity of NPS arriving onto the drug market. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Gavin McLaughlin
- Department of Life and Physical Sciences, School of Science, Athlone Institute of Technology, Dublin Road, Westmeath, Ireland.,Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James's Hospital, Dublin 8, Ireland
| | - Noreen Morris
- Department of Life and Physical Sciences, School of Science, Athlone Institute of Technology, Dublin Road, Westmeath, Ireland
| | - Pierce V Kavanagh
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James's Hospital, Dublin 8, Ireland
| | - Geraldine Dowling
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James's Hospital, Dublin 8, Ireland
| | - John D Power
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James's Hospital, Dublin 8, Ireland.,Forensic Science Laboratory, Garda HQ, Dublin 8, Ireland
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
| | - John O'Brien
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
| | - Brian Talbot
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - Harald H Sitte
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria.,Center for Addiction Research and Science, Medical University Vienna, Waehringerstrasse 13A, 1090, Vienna, Austria
| | - Simon D Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
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Hulshoff A, Lingeman H. Derivatization reactions in the gas—liquid chromatographic analysis of drugs in biological fluids. J Pharm Biomed Anal 1984; 2:337-80. [PMID: 16867717 DOI: 10.1016/0731-7085(84)80040-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alkylation, acylation, silylation and other derivatization reactions applied to the gas chromatographic analysis of drugs in biological matrices are reviewed. Reaction conditions are discussed in relation to reaction mechanisms. Detector-oriented labelling of drugs, and derivatization with chiral reagents for the separation of enantiomers are surveyed. Data on the sample clean-up, derivatization and GLC analysis of more than 300 drugs and related compounds are listed.
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Affiliation(s)
- A Hulshoff
- Department of Analytical Pharmacy, University of Utrecht, Pharmaceutical Laboratory, Catherijnesingel 60, 3511 GH Utrecht, The Netherlands
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