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Carvalho L, Lasek AW. It is not just about transcription: involvement of brain RNA splicing in substance use disorders. J Neural Transm (Vienna) 2024; 131:495-503. [PMID: 38396082 PMCID: PMC11055753 DOI: 10.1007/s00702-024-02740-y] [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: 09/16/2023] [Accepted: 01/04/2024] [Indexed: 02/25/2024]
Abstract
Alternative splicing is a co-transcriptional process that significantly contributes to the molecular landscape of the cell. It plays a multifaceted role in shaping gene transcription, protein diversity, and functional adaptability in response to environmental cues. Recent studies demonstrate that drugs of abuse have a profound impact on alternative splicing patterns within different brain regions. Drugs like alcohol and cocaine modify the expression of genes responsible for encoding splicing factors, thereby influencing alternative splicing of crucial genes involved in neurotransmission, neurogenesis, and neuroinflammation. Notable examples of these alterations include alcohol-induced changes in splicing factors such as HSPA6 and PCBP1, as well as cocaine's impact on PTBP1 and SRSF11. Beyond the immediate effects of drug exposure, recent research has shed light on the role of alternative splicing in contributing to the risk of substance use disorders (SUDs). This is exemplified by exon skipping events in key genes like ELOVL7, which can elevate the risk of alcohol use disorder. Lastly, drugs of abuse can induce splicing alterations through epigenetic modifications. For example, cocaine exposure leads to alterations in levels of trimethylated lysine 36 of histone H3, which exhibits a robust association with alternative splicing and serves as a reliable predictor for exon exclusion. In summary, alternative splicing has emerged as a critical player in the complex interplay between drugs of abuse and the brain, offering insights into the molecular underpinnings of SUDs.
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Affiliation(s)
- Luana Carvalho
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad ST, Box 980613, Richmond, VA, 23298, USA.
| | - Amy W Lasek
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad ST, Box 980613, Richmond, VA, 23298, USA
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Costa AR, Tavares I, Martins I. How do opioids control pain circuits in the brainstem during opioid-induced disorders and in chronic pain? Implications for the treatment of chronic pain. Pain 2024; 165:324-336. [PMID: 37578500 DOI: 10.1097/j.pain.0000000000003026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 07/07/2023] [Indexed: 08/15/2023]
Abstract
ABSTRACT Brainstem areas involved in descending pain modulation are crucial for the analgesic actions of opioids. However, the role of opioids in these areas during tolerance, opioid-induced hyperalgesia (OIH), and in chronic pain settings remains underappreciated. We conducted a revision of the recent studies performed in the main brainstem areas devoted to descending pain modulation with a special focus on the medullary dorsal reticular nucleus (DRt), as a distinctive pain facilitatory area and a key player in the diffuse noxious inhibitory control paradigm. We show that maladaptive processes within the signaling of the µ-opioid receptor (MOR), which entail desensitization and a switch to excitatory signaling, occur in the brainstem, contributing to tolerance and OIH. In the context of chronic pain, the alterations found are complex and depend on the area and model of chronic pain. For example, the downregulation of MOR and δ-opioid receptor (DOR) in some areas, including the DRt, during neuropathic pain likely contributes to the inefficacy of opioids. However, the upregulation of MOR and DOR, at the rostral ventromedial medulla, in inflammatory pain models, suggests therapeutic avenues to explore. Mechanistically, the rationale for the diversity and complexity of alterations in the brainstem is likely provided by the alternative splicing of opioid receptors and the heteromerization of MOR. In conclusion, this review emphasizes how important it is to consider the effects of opioids at these circuits when using opioids for the treatment of chronic pain and for the development of safer and effective opioids.
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Affiliation(s)
- Ana Rita Costa
- Department of Biomedicine, Unit of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal
- IBMC-Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal
- I3S- Institute of Investigation and Innovation in Health, University of Porto, Porto, Portugal. Costa is now with the Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden and Science for Life Laboratory, Solna, Sweden
| | - Isaura Tavares
- Department of Biomedicine, Unit of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal
- IBMC-Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal
- I3S- Institute of Investigation and Innovation in Health, University of Porto, Porto, Portugal. Costa is now with the Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden and Science for Life Laboratory, Solna, Sweden
| | - Isabel Martins
- Department of Biomedicine, Unit of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal
- IBMC-Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal
- I3S- Institute of Investigation and Innovation in Health, University of Porto, Porto, Portugal. Costa is now with the Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden and Science for Life Laboratory, Solna, Sweden
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Liu S, Kang WJ, Abrimian A, Xu J, Cartegni L, Majumdar S, Hesketh P, Bekker A, Pan YX. Alternative Pre-mRNA Splicing of the Mu Opioid Receptor Gene, OPRM1: Insight into Complex Mu Opioid Actions. Biomolecules 2021; 11:biom11101525. [PMID: 34680158 PMCID: PMC8534031 DOI: 10.3390/biom11101525] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/11/2021] [Accepted: 10/11/2021] [Indexed: 12/03/2022] Open
Abstract
Most opioid analgesics used clinically, including morphine and fentanyl, as well as the recreational drug heroin, act primarily through the mu opioid receptor, a class A Rhodopsin-like G protein-coupled receptor (GPCR). The single-copy mu opioid receptor gene, OPRM1, undergoes extensive alternative splicing, creating multiple splice variants or isoforms via a variety of alternative splicing events. These OPRM1 splice variants can be categorized into three major types based on the receptor structure: (1) full-length 7 transmembrane (TM) C-terminal variants; (2) truncated 6TM variants; and (3) single TM variants. Increasing evidence suggests that these OPRM1 splice variants are pharmacologically important in mediating the distinct actions of various mu opioids. More importantly, the OPRM1 variants can be targeted for development of novel opioid analgesics that are potent against multiple types of pain, but devoid of many side-effects associated with traditional opiates. In this review, we provide an overview of OPRM1 alternative splicing and its functional relevance in opioid pharmacology.
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Affiliation(s)
- Shan Liu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Wen-Jia Kang
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Anna Abrimian
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Jin Xu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Luca Cartegni
- Department of Chemical Biology, Ernest Mario School of Pharmacy Rutgers University, Piscataway, NJ 08854, USA;
| | - Susruta Majumdar
- Center for Clinical Pharmacology, University of Health Sciences & Pharmacy and Washington University School of Medicine, St. Louis, MO 63110, USA;
| | - Patrick Hesketh
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Alex Bekker
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Ying-Xian Pan
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
- Correspondence: ; Tel.: +1-973-972-3213
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Understanding Opioid Actions, Pain and Analgesia: A Tribute to Dr. Gavril Pasternak. Cell Mol Neurobiol 2021; 41:827-834. [PMID: 33978862 DOI: 10.1007/s10571-021-01097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 10/21/2022]
Abstract
This special issue is a tribute to our mentor, colleague and friend, Gavril W. Pasternak, MD, PhD. Homage to the breadth and depth of his work (~ 450 publications) over a 40 career in pharmacology and medicine cannot be captured fully in one special issue, but the 22 papers collected herein represent seven of the topics near and dear to Gav's heart, and the colleagues, friends and mentees who held him near to theirs. The seven themes include: (1) sites and mechanisms of opioid actions in vivo; (2) development of novel analgesic agents; (3) opioid tolerance, withdrawal and addiction: mechanisms and treatment; (4) opioid receptor splice variants; (5) novel research tools and approaches; (6) receptor signaling and crosstalk in vitro; and (7) mentorship. This introduction to the issue summarizes contributions and includes formal and personal remembrances of Gav that illustrate his personality, warmth, and dedication to making a difference in patient care and people's lives.
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