1
|
Kaya-Akyüzlü D, Özkan-Kotiloğlu S, Danışman M, Bal C. OPRM1 rs2075572 has potential to affect plasma buprenorphine level in opioid users, but not OPRM1 rs562859. Neurosci Lett 2024; 834:137846. [PMID: 38821204 DOI: 10.1016/j.neulet.2024.137846] [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: 04/08/2024] [Revised: 05/02/2024] [Accepted: 05/28/2024] [Indexed: 06/02/2024]
Abstract
OPRM1 gene encoding mu-opioid receptor (MOR) is the primary candidate gene for buprenorphine (BUP) pharmacogenetics. OPRM1 undergoes alternative splicing leading to multiple MOR subtypes. Thus, in the current study 2 SNPs (rs1799972 and rs562859) were selected due to evidence for their contribution to alternative splicing of OPRM1. The effects of 2 SNPs of OPRM1 gene on plasma buprenorphine and norbuprenorphine levels in a sample of 233 OUD patients receiving BUP/naloxone were examined. Polymorphisms were analyzed by PCR and RFLP. BUP and norbuprenorphine concentrations in plasma were measured by LC-MS/MS. OPRM1 rs2075572 GC + CC (0.12 ng/ml) had significantly higher plasma BUP level compared to GG (0.084 ng/ml) (p = 0.043). Although there was not a statistically significant difference between OPRM1 rs562859 genotypes (p = 0.46), patients with OPRM1 rs562859 CT + TT had higher plasma BUP and BUP-related values as compared to those with CC. In conclusion, the effect of OPRM1 rs2075572 on BUP levels in opioid users' plasma was shown in a Caucasian population for the first time. On the other hand, OPRM1 rs562859 seems not to influence the BUP pharmacology.
Collapse
Affiliation(s)
| | - Selin Özkan-Kotiloğlu
- Kırşehir Ahi Evran University, Faculty of Science and Art, Department of Molecular Biology and Genetics, Kırşehir, Turkey.
| | - Mustafa Danışman
- Ankara Training and Research Hospital AMATEM Clinic, Ankara, Turkey
| | - Ceylan Bal
- Ankara Yıldırım Beyazıt University, Department of Medical Biochemistry, Ankara, Turkey
| |
Collapse
|
2
|
Kaya-Akyüzlü D, Özkan-Kotiloğlu S, Danışman M, Bal C, Oğur B, İspir GZ. OPRD1 rs569356 polymorphism has an effect on plasma norbuprenorphine levels and dose/kg-normalized norbuprenorphine values in individuals with opioid use disorder. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2023; 100:104143. [PMID: 37146669 DOI: 10.1016/j.etap.2023.104143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/07/2023]
Abstract
This study aimed to determine the effects of nine OPRM1, OPRD1 and OPRK1 polymorphisms on plasma BUP and norbuprenorphine (norBUP) concentrations and various treatment responses in a sample of 122 patients receiving BUP/naloxone. Plasma concentrations of BUP and norBUP were detected by LC-MS/MS. PCR-RFLP method was used to genotype polymorphisms. OPRD1 rs569356 GG had significantly lower plasma norBUP concentration (p=0.018), dose- (p=0.049) and dose/kg-normalized norBUP values (p=0.036) compared with AA. Craving and withdrawal symptoms were significantly higher in OPRD1 rs569356 AG+GG relative to AA. There was a statistically significant difference between the OPRD1 rs678849 genotypes in the intensity of anxiety (13.5 for CT+TT and 7.5 for TT). OPRM1 rs648893 TT (18.8±10.8) was significantly different to CC+CT (14.82±11.3; p=0.049) in view of the intensity of depression. This current study provides the first data on a prominent effect of the OPRD1 rs569356 variation on BUP pharmacology due to its metabolite norBUP.
Collapse
Affiliation(s)
| | - Selin Özkan-Kotiloğlu
- Kırşehir Ahi Evran University, Faculty of Science and Art, Department of Molecular Biology and Genetics, Kırşehir, Türkiye
| | - Mustafa Danışman
- Ankara Training and Research Hospital AMATEM Clinic, Ankara, Türkiye
| | - Ceylan Bal
- Ankara Yıldırım Beyazıt University, Department of Medical Biochemistry, Ankara, Türkiye
| | - Begüm Oğur
- Ankara Training and Research Hospital AMATEM Clinic, Ankara, Türkiye
| | | |
Collapse
|
3
|
Diwan AD, Melrose J. Intervertebral disc degeneration and how it leads to low back pain. JOR Spine 2022; 6:e1231. [PMID: 36994466 PMCID: PMC10041390 DOI: 10.1002/jsp2.1231] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 09/23/2022] [Accepted: 10/21/2022] [Indexed: 11/16/2022] Open
Abstract
The purpose of this review was to evaluate data generated by animal models of intervertebral disc (IVD) degeneration published in the last decade and show how this has made invaluable contributions to the identification of molecular events occurring in and contributing to pain generation. IVD degeneration and associated spinal pain is a complex multifactorial process, its complexity poses difficulties in the selection of the most appropriate therapeutic target to focus on of many potential candidates in the formulation of strategies to alleviate pain perception and to effect disc repair and regeneration and the prevention of associated neuropathic and nociceptive pain. Nerve ingrowth and increased numbers of nociceptors and mechanoreceptors in the degenerate IVD are mechanically stimulated in the biomechanically incompetent abnormally loaded degenerate IVD leading to increased generation of low back pain. Maintenance of a healthy IVD is, thus, an important preventative measure that warrants further investigation to preclude the generation of low back pain. Recent studies with growth and differentiation factor 6 in IVD puncture and multi-level IVD degeneration models and a rat xenograft radiculopathy pain model have shown it has considerable potential in the prevention of further deterioration in degenerate IVDs, has regenerative properties that promote recovery of normal IVD architectural functional organization and inhibits the generation of inflammatory mediators that lead to disc degeneration and the generation of low back pain. Human clinical trials are warranted and eagerly anticipated with this compound to assess its efficacy in the treatment of IVD degeneration and the prevention of the generation of low back pain.
Collapse
Affiliation(s)
- Ashish D. Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School University of New South Wales Sydney New South Wales Australia
| | - James Melrose
- Raymond Purves Bone and Joint Research Laboratory Kolling Institute, Sydney University Faculty of Medicine and Health, Northern Sydney Area Health District, Royal North Shore Hospital Sydney New South Wales Australia
- Graduate School of Biomedical Engineering The University of New South Wales Sydney New South Wales Australia
| |
Collapse
|
4
|
Donadoni M, Huang W, Yarandi SS, Burdo TH, Chang SL, Sariyer IK. Modulation of OPRM1 Alternative Splicing by Morphine and HIV-1 Nef. J Neuroimmune Pharmacol 2022; 17:277-288. [PMID: 34420144 PMCID: PMC8859008 DOI: 10.1007/s11481-021-10009-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 08/06/2021] [Indexed: 12/29/2022]
Abstract
Clinically used opioids, such as morphine, activate the mu opioid receptor (MOR) encoded by Opioid Receptor Mu 1 (OPRM1) gene. Examination of the opioid receptor genes showed that the human OPRM1 pre-mRNA undergoes extensive alternative splicing events and capable of expressing 21 isoforms. However, characterization of OPRM1 signaling is generalized, and only one isoform (MOR-1) has been extensively studied. Compounding this issue is the increasing significance of intravenous drug abuse in HIV neuropathogenesis. Here, we investigated the molecular impact of morphine and HIV-1 on regulation of OPRM1 pre-mRNA splicing in in vitro and in vivo models. Our results suggested that morphine treatment specifically induces the alternative splicing of MOR-1X isoform among the other isoforms analyzed in neuronal cells. Interestingly, alternative splicing and expression of MOR-1X isoform was also induced in postmortem brain tissues obtained from people with HIV (PWH). Additionally, treatment of control rats with morphine induced alternative splicing of MOR-1X in the brain regions involved in the reward pathways. More interestingly, HIV-1 transgenic (HIV-1Tg) rats, showed an additive induction of MOR-1X isoform with the exposure to morphine. To further assess the possible role of HIV secretory proteins in alternative splicing of OPRM1 gene, we analyzed the impact of HIV-1 Tat, gp120 and Nef proteins on alternative splicing of MOR-1X isoform. While the Tat and gp120 had no visible effects, treatment of neurons with Nef induced MOR-1X alternative splicing that was comparable to treatment with morphine. Altogether, our results suggest that HIV-1 may alter MOR isoform expression with Nef protein by amplifying the rate of MOR-1X alternative splicing induced by morphine.
Collapse
Affiliation(s)
- Martina Donadoni
- Department of Neuroscience and Center for Neurovirology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Wenfei Huang
- Institute of NeuroImmune Pharmacology and Department of Biological Sciences, Seton Hall University, South Orange, NJ, USA
| | - Shadan S Yarandi
- Department of Neuroscience and Center for Neurovirology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Tricia H Burdo
- Department of Neuroscience and Center for Neurovirology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Sulie L Chang
- Institute of NeuroImmune Pharmacology and Department of Biological Sciences, Seton Hall University, South Orange, NJ, USA.
| | - Ilker K Sariyer
- Department of Neuroscience and Center for Neurovirology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA.
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
HA-MOP knockin mice express the canonical µ-opioid receptor but lack detectable splice variants. Commun Biol 2021; 4:1070. [PMID: 34522000 PMCID: PMC8440528 DOI: 10.1038/s42003-021-02580-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 08/17/2021] [Indexed: 12/31/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are notoriously difficult to detect in native tissues. In an effort to resolve this problem, we have developed a novel mouse model by fusing the hemagglutinin (HA)-epitope tag sequence to the amino-terminus of the µ-opioid receptor (MOP). Although HA-MOP knock-in mice exhibit reduced receptor expression, we found that this approach allowed for highly efficient immunodetection of low abundant GPCR targets. We also show that the HA-tag facilitates both high-resolution imaging and immunoisolation of MOP. Mass spectrometry (MS) confirmed post-translational modifications, most notably agonist-selective phosphorylation of carboxyl-terminal serine and threonine residues. MS also unequivocally identified the carboxyl-terminal 387LENLEAETAPLP398 motif, which is part of the canonical MOP sequence. Unexpectedly, MS analysis of brain lysates failed to detect any of the 15 MOP isoforms that have been proposed to arise from alternative splicing of the MOP carboxyl-terminus. For quantitative analysis, we performed multiple successive rounds of immunodepletion using the well-characterized rabbit monoclonal antibody UMB-3 that selectively detects the 387LENLEAETAPLP398 motif. We found that >98% of HA-tagged MOP contain the UMB-3 epitope indicating that virtually all MOP expressed in the mouse brain exhibit the canonical amino acid sequence. Fritzwanker et al. develop a knock-in transgenic mouse line in which the hemagglutinin epitope tag sequence is fused with the amino-terminus of the µ-opioid receptor. Their model enables more efficient immunodetection of G protein-coupled receptors.
Collapse
|
7
|
Chakrabarti S, Liu NJ, Gintzler AR. Relevance of Mu-Opioid Receptor Splice Variants and Plasticity of Their Signaling Sequelae to Opioid Analgesic Tolerance. Cell Mol Neurobiol 2021; 41:855-862. [PMID: 32804312 DOI: 10.1007/s10571-020-00934-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/01/2020] [Indexed: 10/23/2022]
Abstract
Opioid dose escalation to effectively control pain is often linked to the current prescription opioid abuse epidemic. This creates social as well as medical imperatives to better understand the mechanistic underpinnings of opioid tolerance to develop interventions that minimize it, thereby maximizing the analgesic effectiveness of opioids. Profound opioid analgesic tolerance can be observed in the absence of mu-opioid receptor (MOR) downregulation, aggregate MOR G protein uncoupling, and MOR desensitization, in the absence of impaired G protein coupled receptor kinase phosphorylation, arrestin binding, or endocytosis. Thus, we have explored alternative biochemical sequelae that might better account for opioid analgesic tolerance. Our findings indicate that substantial plasticity among upstream and downstream components of opioid receptor signaling and the emergence of alternative signaling pathways are major contributors to opioid analgesic tolerance. An exemplar of this plasticity is our findings that chronic morphine upregulates the MOR variants MOR-1B2 and MOR-1C1 and phosphorylation of their C-terminal sites not present in MOR-1, events causally associated with the chronic morphine-induced shift in MOR G protein coupling from predominantly Gi/Go inhibitory to Gs-stimulatory adenylyl cyclase signaling. The unique feature(s) of these variants that underlies their susceptibility to adapting to chronic morphine by altering the nature of their G protein coupling reveals the richness and pliability of MOR signaling that is enabled by generating a wide diversity of MOR variants. Furthermore, given differential anatomical expression patterns of MOR variants, MOR splice variant-dependent adaptations to chronic morphine could enable mechanistic underpinnings of tolerance and dependence that are CNS region- and cell-specific.
Collapse
Affiliation(s)
- Sumita Chakrabarti
- Department Obstetrics and Gynecology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA
| | - Nai-Jiang Liu
- Department Obstetrics and Gynecology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA
| | - Alan R Gintzler
- Department Obstetrics and Gynecology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA.
| |
Collapse
|
8
|
Morphine produces potent antinociception, sedation, and hypothermia in humanized mice expressing human mu-opioid receptor splice variants. Pain 2021; 161:1177-1190. [PMID: 32040076 DOI: 10.1097/j.pain.0000000000001823] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Morphine is a strong painkiller acting through mu-opioid receptor (MOR). Full-length 7-transmembrane (TM) variants of MOR share similar amino acid sequences of TM domains in rodents and humans; however, interspecies differences in N- and C-terminal amino acid sequences of MOR splice variants dramatically affect the downstream signaling. Thus, it is essential to develop a mouse model that expresses human MOR splice variants for opioid pharmacological studies. We generated 2 lines of fully humanized MOR mice (hMOR; mMOR mice), line #1 and #2. The novel murine model having human OPRM1 genes and human-specific variants was examined by reverse-transcription polymerase chain reaction and the MinION nanopore sequencing. The differences in the regional distribution of MOR between wild-type and humanized MOR mice brains were detected by RNAscope and radioligand binding assay. hMOR; mMOR mice were characterized in vivo using a tail-flick, charcoal meal, open field, tail suspension, naloxone precipitation tests, and rectal temperature measurement. The data indicated that wild-type and humanized MOR mice exhibited different pharmacology of morphine, including antinociception, tolerance, sedation, and withdrawal syndromes, suggesting the presence of species difference between mouse and human MORs. Therefore, hMOR; mMOR mice could serve as a novel mouse model for pharmacogenetic studies of opioids.
Collapse
|
9
|
Mizoguchi H, Fujii H. Exploring μ-Opioid Receptor Splice Variants as a Specific Molecular Target for New Analgesics. Curr Top Med Chem 2020; 20:2866-2877. [PMID: 32962616 DOI: 10.2174/1568026620666200922113430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/29/2020] [Accepted: 09/03/2020] [Indexed: 11/22/2022]
Abstract
Since a μ-opioid receptor gene containing multiple exons has been identified, the variety of splice variants for μ-opioid receptors have been reported in various species. Amidino-TAPA and IBNtxA have been discovered as new analgesics with different pharmacological profiles from morphine. These new analgesics show a very potent analgesic effect but do not have dependence liability. Interestingly, these analgesics show the selectivity to the morphine-insensitive μ-opioid receptor splice variants. The splice variants, sensitive to these new analgesics but insensitive to morphine, may be a better molecular target to develop the analgesics without side effects.
Collapse
Affiliation(s)
- Hirokazu Mizoguchi
- Department of Physiology and Anatomy, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
| | - Hideaki Fujii
- Laboratory of Medicinal Chemistry and Medical Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| |
Collapse
|
10
|
Pasternak GW, Childers SR, Pan YX. Emerging Insights into Mu Opioid Pharmacology. Handb Exp Pharmacol 2019; 258:89-125. [PMID: 31598835 DOI: 10.1007/164_2019_270] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Opioid analgesics, most of which act through mu opioid receptors, have long represented valuable therapeutic agents to treat severe pain. Concerted drug development efforts for over a 100 years have resulted in a large variety of opioid analgesics used in the clinic, but all of them continue to exhibit the side effects, especially respiratory depression, that have long plagued the use of morphine. The recent explosion in fatalities resulting from overdose of prescription and synthetic opioids has dramatically increased the need for safer analgesics, but recent developments in mu receptor research have provided new strategies to develop such drugs. This chapter reviews recent advances in developing novel opioid analgesics from an understanding of mu receptor structure and function. This includes a summary of the mechanism of agonist binding deduced from the crystal structure of mu receptors. It will also highlight the development of novel agonist mechanisms, including biased agonists, bivalent ligands, and allosteric modulators of mu receptor function, and describe how receptor phosphorylation modulates these pathways. Finally, it will summarize research on the alternative pre-mRNA splicing mechanisms that produces a multiplicity of mu receptor isoforms. Many of these isoforms exhibit different pharmacological specificities and brain circuitry localization, thus providing an opportunity to develop novel drugs with increased therapeutic windows.
Collapse
Affiliation(s)
- Gavril W Pasternak
- Department of Neurology and Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Steven R Childers
- Department of Physiology/Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | - Ying-Xian Pan
- Department of Neurology and Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| |
Collapse
|
11
|
Melo Z, Ishida C, Goldaraz MDLP, Rojo R, Echavarria R. Novel Roles of Non-Coding RNAs in Opioid Signaling and Cardioprotection. Noncoding RNA 2018; 4:ncrna4030022. [PMID: 30227648 PMCID: PMC6162605 DOI: 10.3390/ncrna4030022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/10/2018] [Accepted: 09/12/2018] [Indexed: 12/16/2022] Open
Abstract
Cardiovascular disease (CVD) is a significant cause of morbidity and mortality across the world. A large proportion of CVD deaths are secondary to coronary artery disease (CAD) and myocardial infarction (MI). Even though prevention is the best strategy to reduce risk factors associated with MI, the use of cardioprotective interventions aimed at improving patient outcomes is of great interest. Opioid conditioning has been shown to be effective in reducing myocardial ischemia-reperfusion injury (IRI) and cardiomyocyte death. However, the molecular mechanisms behind these effects are under investigation and could provide the basis for the development of novel therapeutic approaches in the treatment of CVD. Non-coding RNAs (ncRNAs), which are functional RNA molecules that do not translate into proteins, are critical modulators of cardiac gene expression during heart development and disease. Moreover, ncRNAs such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are known to be induced by opioid receptor activation and regulate opioid signaling pathways. Recent advances in experimental and computational tools have accelerated the discovery and functional characterization of ncRNAs. In this study, we review the current understanding of the role of ncRNAs in opioid signaling and opioid-induced cardioprotection.
Collapse
Affiliation(s)
- Zesergio Melo
- CONACyT-Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Sierra Mojada #800 Col. Independencia, Guadalajara 44340, Jalisco, Mexico.
| | - Cecilia Ishida
- Programa de Genomica Computacional, Centro de Ciencias Genomicas, Universidad Nacional Autonoma de Mexico, Cuernavaca 62210, Morelos, Mexico.
| | - Maria de la Paz Goldaraz
- Departamento de Anestesiologia, Hospital de Especialidades UMAE CMNO, Instituto Mexicano del Seguro Social, Guadalajara 44340, Jalisco, Mexico.
| | - Rocio Rojo
- Departamento de Anestesiologia, Hospital de Especialidades UMAE CMNO, Instituto Mexicano del Seguro Social, Guadalajara 44340, Jalisco, Mexico.
| | - Raquel Echavarria
- CONACyT-Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social, Sierra Mojada #800 Col. Independencia, Guadalajara 44340, Jalisco, Mexico.
| |
Collapse
|
12
|
Pasternak GW. Mu Opioid Pharmacology: 40 Years to the Promised Land. ADVANCES IN PHARMACOLOGY 2018; 82:261-291. [DOI: 10.1016/bs.apha.2017.09.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
13
|
Gretton SK, Droney J. Splice variation of the mu-opioid receptor and its effect on the action of opioids. Br J Pain 2015; 8:133-8. [PMID: 26516547 DOI: 10.1177/2049463714547115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
An individual's response to opioids is influenced by a complex combination of genetic, molecular and phenotypic factors.Intra- and inter-individual variations in response to mu opioids have led to the suggestion that mu-opioid receptor subtypes exist.Scientists have now proven that mu-opioid receptor subtypes exist and that they occur through a mechanism promoting protein diversity, called alternative splicing.The ability of mu opioids to differentially activate splice variants may explain some of the clinical differences observed between mu opioids.This article examines how differential activation of splice variants by mu opioids occurs through alternative mu-opioid receptor binding, through differential receptor activation, and as a result of the distinct distribution of variants located regionally and at the cellular level.
Collapse
|
14
|
Gottås A, Øiestad EL, Boix F, Vindenes V, Ripel Å, Thaulow CH, Mørland J. Levels of heroin and its metabolites in blood and brain extracellular fluid after i.v. heroin administration to freely moving rats. Br J Pharmacol 2014; 170:546-56. [PMID: 23865556 DOI: 10.1111/bph.12305] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/24/2013] [Accepted: 07/01/2013] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND PURPOSE Heroin, with low affinity for μ-opioid receptors, has been considered to act as a prodrug. In order to study the pharmacokinetics of heroin and its active metabolites after i.v. administration, we gave a bolus injection of heroin to rats and measured the concentration of heroin and its metabolites in blood and brain extracellular fluid (ECF). EXPERIMENTAL APPROACH After an i.v. bolus injection of heroin to freely moving Sprague-Dawley rats, the concentrations of heroin and metabolites in blood samples from the vena jugularis and in microdialysis samples from striatal brain ECF were measured by ultraperformance LC-MS/MS. KEY RESULTS Heroin levels decreased very fast, both in blood and brain ECF, and could not be detected after 18 and 10 min respectively. 6-Monoacetylmorphine (6-MAM) increased very rapidly, reaching its maximal concentrations after 2.0 and 4.3 min, respectively, and falling thereafter. Morphine increased very slowly, reaching its maximal levels, which were six times lower than the highest 6-MAM concentrations, after 12.6 and 21.3 min, with a very slow decline during the rest of the experiment and only surpassing 6-MAM levels at least 30 min after injection. CONCLUSIONS AND IMPLICATIONS After an i.v. heroin injection, 6-MAM was the predominant opioid present shortly after injection and during the first 30 min, not only in the blood but also in rat brain ECF. 6-MAM might therefore mediate most of the effects observed shortly after heroin intake, and this finding questions the general assumption that morphine is the main and most important metabolite of heroin.
Collapse
Affiliation(s)
- A Gottås
- Department of Drug Abuse Research and Method Development, Division of Forensic Medicine and Drug Abuse Research, Norwegian Institute of Public Health, Oslo, Norway
| | | | | | | | | | | | | |
Collapse
|
15
|
Grinnell SG, Majumdar S, Narayan A, Le Rouzic V, Ansonoff M, Pintar JE, Pasternak GW. Pharmacologic characterization in the rat of a potent analgesic lacking respiratory depression, IBNtxA. J Pharmacol Exp Ther 2014; 350:710-8. [PMID: 24970924 DOI: 10.1124/jpet.114.213199] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
IBNtxA (3'-iodobenzoyl-6β-naltrexamide) is a potent analgesic in mice lacking many traditional opioid side effects. In mice, it displays no respiratory depression, does not produce physical dependence with chronic administration, and shows no cross-tolerance to morphine. It has limited effects on gastrointestinal transit and shows no reward behavior. Biochemical studies indicate its actions are mediated through a set of μ-opioid receptor clone MOR-1 splice variants associated with exon 11 that lack exon 1 and contain only six transmembrane domains. Like the mouse and human, rats express exon 11-associated splice variants that also contain only six transmembrane domains, raising the question of whether IBNtxA would have a similar pharmacologic profile in rats. When given systemically, IBNtxA is a potent analgesic in rats, with an ED50 value of 0.89 mg/kg s.c., approximately 4-fold more potent than morphine. It shows no analgesic cross-tolerance in morphine-pelleted rats. IBNtxA displays no respiratory depression as measured by blood oxygen saturation. In contrast, oximetry shows that an equianalgesic dose of morphine lowers blood oxygen saturation values by 30%. IBNtxA binding is present in a number of brain regions, with the thalamus standing out with very high levels and the cerebellum with low levels. As in mice, IBNtxA is a potent analgesic in rats with a favorable pharmacologic profile and reduced side effects.
Collapse
Affiliation(s)
- Steven G Grinnell
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| | - Susruta Majumdar
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| | - Ankita Narayan
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| | - Valerie Le Rouzic
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| | - Michael Ansonoff
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| | - John E Pintar
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| | - Gavril W Pasternak
- Department of Neurology (S.M., G.W.P.) and Molecular Pharmacology and Chemistry Program (V.L.R., G.W.P.), Memorial Sloan-Kettering Cancer Center, New York, New York; Neuroscience (S.G.G., A.N., G.W.P.) and Pharmacology (G.W.P.) Graduate Programs, Weill Cornell Graduate School of Medical Sciences, New York, New York; and Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey (M.A., J.E.P.)
| |
Collapse
|
16
|
Xu J, Xu M, Bolan E, Gilbert AK, Pasternak GW, Pan YX. Isolating and characterizing three alternatively spliced mu opioid receptor variants: mMOR-1A, mMOR-1O, and mMOR-1P. Synapse 2014; 68:144-52. [PMID: 24375714 DOI: 10.1002/syn.21727] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/27/2013] [Accepted: 12/16/2013] [Indexed: 12/21/2022]
Abstract
Extensive alternative pre-mRNA splicing of the mu opioid receptor gene, OPRM1, has demonstrated an array of splice variants in mice, rats and humans. Three classes of splice variants have been identified: full-length seven transmembrane (TM) domain variants with C-terminal splicing, truncated 6TM variants and single TM variants. The current studies isolates and characterizes an additional three full-length C-terminal splice variants generated from the mouse OPRM1 gene: mMOR-1A, mMOR-1O, and mMOR-1P. Using RT-qPCR, we demonstrated differential expression of these variants' mRNAs among selected brain regions, supporting region-specific alternative splicing. When expressed in Chinese Hamster Ovary cells, all the variants displayed high mu binding affinity and selectivity with subtle differences in the affinities toward some agonists. [³⁵S]γGTP binding assays revealed marked differences in agonist-induced G protein activation in both potency and efficacy among the variants. Together with the previous studies of mu agonist-induced phosphorylation and internalization in several carboxyl terminal splice variants, the current studies further suggest the existence of biased signaling of various agonists within each individual variant and/or among different variants.
Collapse
Affiliation(s)
- Jin Xu
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York, 10065
| | | | | | | | | | | |
Collapse
|
17
|
Pasternak GW. Opioids and their receptors: Are we there yet? Neuropharmacology 2014; 76 Pt B:198-203. [PMID: 23624289 PMCID: PMC4216569 DOI: 10.1016/j.neuropharm.2013.03.039] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/02/2013] [Accepted: 03/26/2013] [Indexed: 01/06/2023]
Abstract
Opioids have an important place in pharmacology. While their clinical use as analgesics is fundamental in medicine, their use is constrained by their side-effects and abuse potential. Pharmacologists have sought analgesics lacking side-effects and the abuse liability of the current agents. The identification of the opioid receptors in 1973 marked the beginning of our understanding of the molecular mechanisms of these agents. The isolation of the opioid peptides quickly followed, along with the classification of three families of opioid receptors. Clinicians have long been aware of subtle differences among the mu opioids that were not easily reconciled with a single receptor and selective antagonists implied two subdivisions of mu receptors. However, the cloning of the mu opioid receptor MOR-1 has led to the realization of the extensive complexity of the mu opioid receptor gene and its vast array of splice variants. Many of these splice variants are truncated and do not conform to the structure of traditional G-protein coupled receptors. Yet, evidence now shows that they are quite important and may prove valuable targets in the development of potent analgesics lacking the undesirable properties of current opioids. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
Collapse
Affiliation(s)
- Gavril W Pasternak
- Molecular Pharmacology and Chemistry Program, Department of Neurology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA.
| |
Collapse
|
18
|
Lu Z, Xu J, Xu M, Pasternak GW, Pan YX. Morphine regulates expression of μ-opioid receptor MOR-1A, an intron-retention carboxyl terminal splice variant of the μ-opioid receptor (OPRM1) gene via miR-103/miR-107. Mol Pharmacol 2013; 85:368-80. [PMID: 24302561 DOI: 10.1124/mol.113.089292] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The μ-opioid receptor (MOR-1) gene OPRM1 undergoes extensive alternative splicing, generating an array of splice variants. Of these variants, MOR-1A, an intron-retention carboxyl terminal splice variant identical to MOR-1 except for the terminal intracellular tail encoded by exon 3b, is quite abundant and conserved from rodent to humans. Increasing evidence indicates that miroRNAs (miRNAs) regulate MOR-1 expression and that μ agonists such as morphine modulate miRNA expression. However, little is known about miRNA regulation of the OPRM1 splice variants. Using 3'-rapid amplification cDNA end and Northern blot analyses, we identified the complete 3'-untranslated region (3'-UTR) for both mouse and human MOR-1A and their conserved polyadenylation site, and defined the role the 3'-UTR in mRNA stability using a luciferase reporter assay. Computer models predicted a conserved miR-103/107 targeting site in the 3'-UTR of both mouse and human MOR-1A. The functional relevance of miR-103/107 in regulating expression of MOR-1A protein through the consensus miR-103/107 binding sites in the 3'-UTR was established by using mutagenesis and a miR-107 inhibitor in transfected human embryonic kidney 293 cells and Be(2)C cells that endogenously express human MOR-1A. Chronic morphine treatment significantly upregulated miR-103 and miR-107 levels, leading to downregulation of polyribosome-associated MOR-1A in both Be(2)C cells and the striatum of a morphine-tolerant mouse, providing a new perspective on understanding the roles of miRNAs and OPRM1 splice variants in modulating the complex actions of morphine in animals and humans.
Collapse
Affiliation(s)
- Zhigang Lu
- Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York
| | | | | | | | | |
Collapse
|
19
|
Abstract
Opiates are among the oldest medications available to manage a number of medical problems. Although pain is the current focus, early use initially focused upon the treatment of dysentery. Opium contains high concentrations of both morphine and codeine, along with thebaine, which is used in the synthesis of a number of semisynthetic opioid analgesics. Thus, it is not surprising that new agents were initially based upon the morphine scaffold. The concept of multiple opioid receptors was first suggested almost 50 years ago (Martin, 1967), opening the possibility of new classes of drugs, but the morphine-like agents have remained the mainstay in the medical management of pain. Termed mu, our understanding of these morphine-like agents and their receptors has undergone an evolution in thinking over the past 35 years. Early pharmacological studies identified three major classes of receptors, helped by the discovery of endogenous opioid peptides and receptor subtypes-primarily through the synthesis of novel agents. These chemical biologic approaches were then eclipsed by the molecular biology revolution, which now reveals a complexity of the morphine-like agents and their receptors that had not been previously appreciated.
Collapse
Affiliation(s)
- Gavril W Pasternak
- Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
| | | |
Collapse
|
20
|
Xu J, Xu M, Brown T, Rossi GC, Hurd YL, Inturrisi CE, Pasternak GW, Pan YX. Stabilization of the μ-opioid receptor by truncated single transmembrane splice variants through a chaperone-like action. J Biol Chem 2013; 288:21211-21227. [PMID: 23760268 DOI: 10.1074/jbc.m113.458687] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The μ-opioid receptor gene, OPRM1, undergoes extensive alternative pre-mRNA splicing, as illustrated by the identification of an array of splice variants generated by both 5' and 3' alternative splicing. The current study reports the identification of another set of splice variants conserved across species that are generated through exon skipping or insertion that encodes proteins containing only a single transmembrane (TM) domain. Using a Tet-Off system, we demonstrated that the truncated single TM variants can dimerize with the full-length 7-TM μ-opioid receptor (MOR-1) in the endoplasmic reticulum, leading to increased expression of MOR-1 at the protein level by a chaperone-like function that minimizes endoplasmic reticulum-associated degradation. In vivo antisense studies suggested that the single TM variants play an important role in morphine analgesia, presumably through modulation of receptor expression levels. Our studies suggest the functional roles of truncated receptors in other G protein-coupled receptor families.
Collapse
Affiliation(s)
- Jin Xu
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Ming Xu
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Taylor Brown
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Grace C Rossi
- the Department of Psychology, CW Post College, Long Island University, Brookville, New York 11568
| | - Yasmin L Hurd
- the Department of Psychiatry and Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029, and
| | - Charles E Inturrisi
- the Department of Pharmacology, Weill Cornell Medical College, New York, New York 10065
| | - Gavril W Pasternak
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065,; the Department of Pharmacology, Weill Cornell Medical College, New York, New York 10065.
| | - Ying-Xian Pan
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065,.
| |
Collapse
|
21
|
Ding S, Chen B, Zheng Y, Lu Q, Liu L, Zhuge QC. Association study of OPRM1 polymorphisms with Schizophrenia in Han Chinese population. BMC Psychiatry 2013; 13:107. [PMID: 23560613 PMCID: PMC3641981 DOI: 10.1186/1471-244x-13-107] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 03/12/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The expression of μ-opioid receptor has important role in cognitive dysfunction in Schizophrenia (SZ). The results of studies about the association of polymorphisms of μ-opioid receptor gene (OPRM1) with SZ were inconsistent. METHODS We conducted a case-control study to investigate the genetic association between OPRM1 polymorphisms and SZ among the Han chinese population. 264 SZ patients and 264 age-matched control subjects were recruited. Four SNPs of OPRM1 were successfully genotyped by using PCR-RFLP. RESULTS Of four polymorphisms, rs1799971 and rs2075572 were shown to associate with SZ. Compared with the A allele of rs1799971 and C allele of rs2075572, the G allele of rs1799971 and rs2075572 was associated with an almost 0.46-fold risk (OR=0.46, 95% CI: 0.357-0.59, P<0.01) and 0.7-fold risk (OR=0.707, 95% CI: 0.534-0.937, P=0.015) of the occurrence of SZ,. When subjects were divided by gender, rs1799971 remained significant difference only in males (OR=0.309, 95% CI: 0.218-0.439 for G allele, P<0.01), and rs2075572 only in females (OR=0.399, 95% CI: 0.246-0.648 for G allele, P<0.01). In secondary analysis with subsets of patients, the G allele of rs1799971 (compared to the A allele) was associated with a decreased risk of all patients and male patients with apathy symptoms (OR=0.086, 95% CI: 0.048-0.151, P=0.01; OR=0.083, 95% CI: 0.045-0.153, P<0.01), and the G allele of rs2075572 (compared to the C allele) was associated with a decreased risk of all patients and female patients with positive family history (OR=0.468, 95% CI: 0.309-0.71, P<0.01; OR=0.34, 95% CI: 0.195-0.593, P<0.01). In addition, haplotype analysis revealed that two SNP haplotypes (A-C-C-G and G-C-C-A) were associated with decreased risks of SZ (P<0.01). The other two (G-C-C-G and G-G-C-G) with increased risks of SZ (P<0.01). CONCLUSIONS The present study demonstrated for the first time that the OPRM1 polymorphism may be a risk factor for schizophrenia in the Han Chinese. Further studies are needed to give a global view of this polymorphism in pathogenesis of schizophrenia in a large-scale sample, family-based association design or well-defined subgroups of schizophrenia.
Collapse
Affiliation(s)
- Saidan Ding
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disease Research, Department of Surgery, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Bicheng Chen
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disease Research, Department of Surgery, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Yong Zheng
- Clinical Laboratory, the Fifth People’s Hospital of Ruian city, Wenzhou, Zhejiang, China
| | - Qin Lu
- Neurosurgery Department, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Leping Liu
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disease Research, Department of Surgery, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Qǐ -Chuan Zhuge
- Neurosurgery Department, the First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| |
Collapse
|
22
|
Andersen S, Baar C, Fladvad T, Laugsand EA, Skorpen F. The N-terminally truncated µ3 and µ3-like opioid receptors are transcribed from a novel promoter upstream of exon 2 in the human OPRM1 gene. PLoS One 2013; 8:e71024. [PMID: 23951073 PMCID: PMC3741380 DOI: 10.1371/journal.pone.0071024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 07/01/2013] [Indexed: 11/19/2022] Open
Abstract
The human µ opioid receptor gene, OPRM1, produces a multitude of alternatively spliced transcripts encoding full-length or truncated receptor variants with distinct pharmacological properties. The majority of these transcripts are transcribed from the main promoter upstream of exon 1, or from alternate promoters associated with exons 11 and 13. Two distinct transcripts encoding six transmembrane domain (6TM) hMOR receptors, µ3 and µ3-like, have been reported, both starting with the first nucleotide in exon 2. However, no mechanism explaining their initiation at exon 2 has been presented. Here we have used RT-PCR with RNA from human brain tissues to demonstrate that the µ3 and µ3-like transcripts contain nucleotide sequences from the intron 1-exon 2 boundary and are transcribed from a novel promoter located upstream of exon 2. Reporter gene assays confirmed the ability of the novel promoter to drive transcription in human cells, albeit at low levels. We also report the identification of a "full-length" seven transmembrane domain (7TM) version of µ3, hMOR-1A2, which also contains exon 1, and a novel transcript, hMOR-1Y2, with the potential to encode the previously reported hMOR-1Y receptor, but with exon Y spliced to exon 4 instead of exon 5 as in hMOR-1Y. Heterologous expression of GFP-tagged hMOR variants in HEK 293 cells showed that both 6TM receptors were retained in the intracellular compartment and were unresponsive to exogenous opioid exposure as assessed by their ability to redistribute or affect cellular cAMP production, or to promote intracellular Ca(2+) release. Co-staining with an antibody specific for endoplasmic reticulum (ER) indicated that the µ3-like receptor was retained at the ER after synthesis. 7TM receptors hMOR-1A2 and hMOR-1Y2 resided in the plasma membrane, and were responsive to opioids. Notably, hMOR-1A2 exhibits novel functional properties in that it did not internalize in response to the opioid peptide [D-Ala2, N-Me-Phe4, Gly-ol5]enkephalin (DAMGO).
Collapse
Affiliation(s)
- Sonja Andersen
- Department of Cancer Research and Molecular Medicine and European Palliative Care Research Centre, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Cecilie Baar
- Department of Laboratory Medicine, Children's and Women's Health and European Palliative Care Research Centre, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Torill Fladvad
- Department of Laboratory Medicine, Children's and Women's Health and European Palliative Care Research Centre, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Eivor Alette Laugsand
- Department of Cancer Research and Molecular Medicine and European Palliative Care Research Centre, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Frank Skorpen
- Department of Laboratory Medicine, Children's and Women's Health and European Palliative Care Research Centre, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- * E-mail:
| |
Collapse
|
23
|
AL-Eitan LN, Jaradat SA, Su SYS, Tay GK, Hulse GK. Mu opioid receptor (OPRM1) as a predictor of treatment outcome in opiate-dependent individuals of Arab descent. Pharmgenomics Pers Med 2012; 5:99-111. [PMID: 23226066 PMCID: PMC3513232 DOI: 10.2147/pgpm.s33351] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND A number of research studies on the genetics of opiate dependence have focused on the μ-opioid receptor (OPRM1), which is a primary target for opiates. This study aims to identify genetic polymorphisms within the OPRM1 gene involved in response to the biopsychosocial treatment in opiate-dependent individuals of Arab descent. METHODS Unrelated Jordanian Nationals of Arab descent (N = 183) with opiate dependence were selected for this study. These individuals, all males, met the DSM-IV criteria for opiate dependence and were undergoing a voluntary 8-week treatment program at a Jordanian Drug Rehabilitation Centre. All individuals were genotyped for 22 single nucleotide polymorphisms (SNPs) within the OPRM1 gene using the Sequenom MassARRAY(®) system (iPLEX GOLD). Statistical analyses were carried out using the R package. RESULTS Patients receiving biopsychosocial treatment showed that there was a significant difference in their OPRM1 SNPs' genotyping distribution between good, moderate, and poor responders to the treatment at two sites (rs6912029 [G-172T], and rs12205732 [G-1510A], P < 0.05, Fisher's exact test). CONCLUSION This study is the first report of an association between the OPRM1 G-172T and G-1510A polymorphisms and treatment response for opiate dependence. Specifically, this study demonstrated that the OPRM1 GG-172 and GG-1510 genotypes were more frequent among patients who were nonresponders to the biopsychosocial treatment. However, further pharmacogenetic studies in a larger cohort of opiate-dependent patients of Arab descent are needed to confirm these findings and identify individuals with increased chance of relapse.
Collapse
Affiliation(s)
| | - Saied A Jaradat
- Princess Haya Biotechnology Center, Jordan University of Science and Technology, Irbid,
Jordan
| | | | | | - Gary K Hulse
- School of Psychiatry and Clinical Neurosciences
- Unit for Research and Education in Alcohol and Drugs, Queen Elizabeth II Medical Centre, The University of Western Australia, Crawley, WA,
Australia
| |
Collapse
|
24
|
Regan PM, Dave RS, Datta PK, Khalili K. Epigenetics of µ-opioid receptors: intersection with HIV-1 infection of the central nervous system. J Cell Physiol 2012; 227:2832-41. [PMID: 22034138 DOI: 10.1002/jcp.24004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The abuse of intravenous drugs, such as heroin, has become a major public health concern due to the increased risk of HIV-1 infection. Opioids such as heroin were originally identified and subsequently abused for their analgesic effects. However, many investigations have found additional effects of opioids, including regulation of the immune system. As such, chronic opioid abuse has been shown to promote HIV-1 pathogenesis and facilitate HIV-1-associated neurocognitive dysfunction. Clinical opioids, such as morphine and methadone, as well as illicit opioids, such as heroin, exert their effects primarily through interactions with the µ-opioid receptor (MOR). However, the mechanisms by which opioids enhance neurocognitive dysfunction through MOR-mediated signaling pathways are not completely understood. New findings in the regulation of MOR expression, particularly epigenetic and transcriptional regulation as well as alternative splicing, sheds new insights into possible mechanisms of HIV-1 and opiate synergy. In this review, we identify mechanisms regulating MOR expression and propose novel mechanisms by which opioids and HIV-1 may modulate this regulation. Additionally, we suggest that differential regulation of newly identified MOR isoforms by opioids and HIV-1 has functional consequence in enhancing HIV-1 neurocognitive dysfunction.
Collapse
Affiliation(s)
- Patrick M Regan
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, PA, USA
| | | | | | | |
Collapse
|
25
|
Majumdar S, Subrath J, Le Rouzic V, Polikar L, Burgman M, Nagakura K, Ocampo J, Haselton N, Pasternak AR, Grinnell S, Pan YX, Pasternak GW. Synthesis and evaluation of aryl-naloxamide opiate analgesics targeting truncated exon 11-associated μ opioid receptor (MOR-1) splice variants. J Med Chem 2012; 55:6352-62. [PMID: 22734622 DOI: 10.1021/jm300305c] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
3-Iodobenzoylnaltrexamide 1 (IBNtxA) is a potent analgesic acting through a novel receptor target that lack many side-effects of traditional opiates composed, in part, of exon 11-associated truncated six transmembrane domain MOR-1 (6TM/E11) splice variants. To better understand the SAR of this drug target, a number of 4,5-epoxymorphinan analogues were synthesized. Results show the importance of a free 3-phenolic group, a phenyl ring at the 6 position, an iodine at the 3'or 4' position of the phenyl ring, and an N-allyl or c-propylmethyl group to maintain high 6TM/E11 affinity and activity. 3-Iodobenzoylnaloxamide 15 (IBNalA) with a N-allyl group displayed lower δ opioid receptor affinity than its naltrexamine analogue, was 10-fold more potent an analgesic than morphine, elicited no respiratory depression or physical dependence, and only limited inhibition of gastrointestinal transit. Thus, the aryl-naloxamide scaffold can generate a potent analgesic acting through the 6TM/E11 sites with advantageous side-effect profile and greater selectivity.
Collapse
Affiliation(s)
- Susruta Majumdar
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Differential expression and HIV-1 regulation of μ-opioid receptor splice variants across human central nervous system cell types. J Neurovirol 2012; 18:181-90. [PMID: 22528479 DOI: 10.1007/s13365-012-0096-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 03/21/2012] [Accepted: 03/26/2012] [Indexed: 01/06/2023]
Abstract
The μ-opioid receptor (MOR) is known to undergo extensive alternative splicing as numerous splice variants of MOR have been identified. However, the functional significance of MOR variants, as well as how splice variants other than MOR-1 might differentially regulate human immunodeficiency virus type-1 (HIV-1) pathogenesis in the central nervous system (CNS), or elsewhere, has largely been ignored. Our findings suggest that there are specific differences in the MOR variant expression profile among CNS cell types, and that the expression levels of these variants are differentially regulated by HIV-1. While MOR-1A mRNA was detected in astroglia, microglia, and neurons, MOR-1 and MOR-1X were only found in astroglia. Expression of the various forms of MOR along with the chimeric G protein qi5 in HEK-293T cells resulted in differences in calcium/NFAT signaling with morphine treatment, suggesting that MOR variant expression might underlie functional differences in MOR-effector coupling and intracellular signaling across different cell types. Furthermore, the data suggest that the expression of MOR-1 and other MOR variants may also be differentially regulated in the brains of HIV-infected subjects with varying levels of neurocognitive impairment. Overall, the results reveal an unexpected finding that MOR-1 may not be the predominant form of MOR expressed by some CNS cell types and that other splice variants of MOR-1, with possible differing functions, may contribute to the diversity of MOR-related processes in the CNS.
Collapse
|
27
|
Zhu ZP, Badisa RB, Palm DE, Goodman CB. Regulation of rat MOR-1 gene expression after chronic intracerebroventricular administration of morphine. Mol Med Rep 2011; 5:513-6. [PMID: 22089925 DOI: 10.3892/mmr.2011.677] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Accepted: 10/19/2011] [Indexed: 11/05/2022] Open
Abstract
The µ-opioid receptor is the primary site for the action of morphine. In the present study, we investigated the regulation of the µ-opioid receptor mRNA levels in the locus ceruleus, ventral tegmental area, nucleus accumbens and hypothalamus of the rat brain following intracerebroventricular administration of morphine for 7 days. The isolated mRNA from these regions was subjected to real-time quantitative RT-PCR to determine the regulation of µ-opioid receptor gene expression. It was observed that 7 days of treatment with morphine significantly down-regulated the µ-opioid receptor mRNA levels in the hypothalamus of the brain in comparison to the control group. However, the µ-opioid receptor levels in the locus ceruleus, ventral tegmental area and nucleus accumbens regions remained the same as the control levels. Down-regulation of µ-opioid receptor mRNA levels in the hypothalamus region of the brain indicates the probable role of opioids to influence neuroendocrine function. The results further indicate that cellular adaptation for morphine tolerance is tissue-specific. These findings help us to understand the mechanism of morphine tolerance in various regions of the brain.
Collapse
Affiliation(s)
- Zhi-Ping Zhu
- College of Pharmacy and Pharmaceutical Sciences, Florida A and M University, Tallahassee, FL 32307, USA
| | | | | | | |
Collapse
|
28
|
Xu J, Xu M, Rossi GC, Pasternak GW, Pan YX. Identification and characterization of seven new exon 11-associated splice variants of the rat μ opioid receptor gene, OPRM1. Mol Pain 2011; 7:9. [PMID: 21255438 PMCID: PMC3057186 DOI: 10.1186/1744-8069-7-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 01/21/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The mouse mu opioid receptor (OPRM1) gene undergoes extensive alternative splicing at both the 3'- and 5'-ends of the gene. Previously, several C-terminal variants generated through 3' splicing have been identified in the rat OPRM1 gene. In both mice and humans 5' splicing generates a number of exon 11-containing variants. Studies in an exon 11 knockout mouse suggest the functional importance of these exon 11-associated variants in mediating the analgesic actions of a subset of mu opioids, including morphine-6β-glucuronide (M6G) and heroin, but not others such as morphine and methadone. We now have examined 5' splicing in the rat. RESULTS The current studies identified in the rat a homologous exon 11 and seven exon 11-associated variants, suggesting conservation of exon 11 and its associated variants among mouse, rat and human. RT-PCR revealed marked differences in the expression of these variants across several brain regions, implying region-specific mRNA processing of the exon 11-associated variants. Of the seven rat exon 11-associated variants, four encoded the identical protein as found in rMOR-1, two predicted 6 TM variants, and one, rMOR-1H2, generated a novel N-terminal variant in which a stretch of an additional 50 amino acids was present at the N-terminus of the previously established rMOR-1 sequence. When expressed in CHO cells, the presence of the additional 50 amino acids in rMOR-1H2 significantly altered agonist-induced G protein activation with little effect on opioid binding. CONCLUSION The identification of the rat exon 11 and its associated variants further demonstrated conservation of 5' splicing in OPRM1 genes among rodents and humans. The functional relevance of these exon 11 associated variants was suggested by the region-specific expression of their mRNAs and the influence of the N-terminal sequence on agonist-induced G protein coupling in the novel N-terminal variant, rMOR-1H2. The importance of the exon 11-associated variants in mice in M6G and heroin analgesia revealed in the exon 11 knockout mouse implies that these analogous rat variants may also play similar roles in rat. The complexity created by alternative splicing of the rat OPRM1 gene may provide important insights of understanding the diverse responses to the various μ opioids seen in rats.
Collapse
Affiliation(s)
- Jin Xu
- Department of Neurology and Program in Molecular Pharmacology and Chemistry, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | | | | | | | | |
Collapse
|
29
|
Kim DH, Schwartz CE. The genetics of pain: implications for evaluation and treatment of spinal disease. Spine J 2010; 10:827-40. [PMID: 20615760 DOI: 10.1016/j.spinee.2010.05.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/07/2010] [Accepted: 05/22/2010] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Variability in human pain experience appears to be at least partially determined by genetic inheritance. To the extent that awareness of individual pain sensitivity and the tendency to develop chronic pain after injury or surgery would be informative for clinical decision making, development and use of genetic testing for specific pain markers could contribute to improved outcomes in management of spinal disease. PURPOSE To review important and illustrative results from both classical and modern pain genetics studies and to introduce readers to critical definitions and concepts necessary to interpret the growing body of genetics literature relevant to spinal disease. STUDY DESIGN/SETTING Literature review and commentary. METHODS A review was performed of published English language studies in which genetic techniques were used to analyze the molecular basis of nociceptive signaling or processing with a particular emphasis on studies addressing genetic determinants of interindividual variability in pain sensitivity or predisposition to chronic pain. RESULTS There is compelling evidence indicating that interindividual differences in pain sensitivity and the risk of developing chronic pain syndromes are genetically determined. Despite a growing list of putative "pain genes," genetic association studies remain plagued with difficulty replicating initial findings in different cohorts. CONCLUSIONS Genome-wide association studies are potentially powerful means of identifying clinically relevant genetic markers predicting disease susceptibility, severity, and treatment response. However, accurate results require rigorous study design with use of large homogeneous populations and precise phenotypes.
Collapse
Affiliation(s)
- David H Kim
- Department of Orthopaedic Surgery, Tufts University Medical School, New England Baptist Hospital, Boston, MA 02120, USA.
| | | |
Collapse
|
30
|
Mohan S, Davis RL, DeSilva U, Stevens CW. Dual regulation of mu opioid receptors in SK-N-SH neuroblastoma cells by morphine and interleukin-1β: evidence for opioid-immune crosstalk. J Neuroimmunol 2010; 227:26-34. [PMID: 20615556 DOI: 10.1016/j.jneuroim.2010.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 05/27/2010] [Accepted: 06/03/2010] [Indexed: 11/19/2022]
Abstract
Treatment of SK-N-SH cells with morphine and interleukin-1beta (IL-1β) produced dual regulation of the mRNA for the human mu opioid receptor (MOR) protein. Morphine produced a decrease in the MOR mRNA while IL-1β increased it, as assessed by real-time quantitative PCR. These data were consistent with immunocytochemical studies of treated and untreated cells. Morphine-mediated down-regulation of MOR was blocked by naltrexone and IL-1β-induced up-regulation of MOR was blocked by interleukin-1 receptor type 1 antagonist. Immune-opioid crosstalk was examined by IL-1β and morphine co-treatment. These data are the first to show dual regulation of MOR in neuroblastoma cells.
Collapse
MESH Headings
- Cell Line, Tumor
- Down-Regulation/genetics
- Down-Regulation/immunology
- Humans
- Interleukin-1beta/antagonists & inhibitors
- Interleukin-1beta/metabolism
- Interleukin-1beta/physiology
- Morphine/metabolism
- Morphine/pharmacology
- Neuroblastoma/immunology
- Neuroblastoma/metabolism
- Neuroblastoma/pathology
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/biosynthesis
- Receptor Cross-Talk/drug effects
- Receptor Cross-Talk/immunology
- Receptors, Interleukin-1 Type I/antagonists & inhibitors
- Receptors, Interleukin-1 Type I/physiology
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Up-Regulation/genetics
- Up-Regulation/immunology
Collapse
Affiliation(s)
- Shekher Mohan
- Department of Pharmacology and Physiology, Oklahoma State University-Center for Health Sciences, 1111 West 17(th) Street, Tulsa, OK 74107, USA
| | | | | | | |
Collapse
|
31
|
Schnell SA, Wessendorf MW. Lack of evidence for the μ-opioid receptor splice variant MOR1Cin rats. J Comp Neurol 2009; 517:452-8. [DOI: 10.1002/cne.22175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
32
|
Hadjimarkou MM, Abbadie C, Kasselman LJ, Pan YX, Pasternak GW, Bodnar RJ. Changes in mouse mu opioid receptor Exon 7/8-like immunoreactivity following food restriction and food deprivation in rats. Synapse 2009; 63:585-97. [PMID: 19301417 DOI: 10.1002/syn.20639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Opioid agonists and antagonists respectively increase and decrease food intake. That selective mu opioid antagonists are more effective than antisense probes directed against the mu opioid receptor (MOR-1) gene in reducing deprivation-induced feeding suggests a role for isoforms. Both food restriction and deprivation alter protein and mRNA levels of opioid peptides and receptors. Antisera directed against Exon 4 of the MOR-1-like immunoreactivity (LI) (Exon 4) clone or directed against mouse Exons 7/8 (mE7/8-LI) revealed high levels of immunoreactivity in brain nuclei related to feeding behavior. Therefore, the present study assessed MOR-1LI and mE7/8-LI in hypothalamic and extrahypothalamic sites in rats exposed to ad libitum feeding, food restriction (2, 7, 14 days), or food deprivation (24, 48 h). MOR-1-LI displayed robust reactivity, but was insensitive to food restriction or deprivation. mE7/8-LI, both in terms of cell counts and relative optical density, was significantly and selectively increased in the dorsal and ventral parvocellular subdivisions of the hypothalamic paraventricular nucleus in food-restricted (14 days) rats, but all other restriction or deprivation regimens were ineffective in other hypothalamic nuclei. In contrast, significant and site-specific decreases in relative optical density in the rostral part of the nucleus tractus solitarius (NTS) were observed in food-restricted (2, 7 days) or food-deprived (24, 48 h) animals, but these regimens were ineffective in the other extrahypothalamic sites. This study indicates the sensitivity of this mE7/8-LI probe in the hypothalamic parvocellular paraventricular nucleus and rostral NTS to food restriction and deprivation in rats.
Collapse
Affiliation(s)
- Maria M Hadjimarkou
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, New York 11367, USA
| | | | | | | | | | | |
Collapse
|
33
|
Functional characterization of human variants of the mu-opioid receptor gene. Proc Natl Acad Sci U S A 2009; 106:10811-6. [PMID: 19528663 DOI: 10.1073/pnas.0904509106] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Opioids and their receptors have an important role in analgesia and alcohol and substance use disorders (ASUD). We have identified several naturally occurring amino acid changing variants of the human mu-opioid receptor (MOR), and assessed the functional consequences of these previously undescribed variants in stably expressing cell lines. Several of these variants had altered trafficking and signaling properties. We found that an L85I variant showed significant internalization in response to morphine, in contrast to the WT MOR, which did not internalize in response to morphine. Also, when L85I and WT receptor were coexpressed, WT MOR internalized with the L85I MOR, suggesting that, in the heterozygous condition, the L85I phenotype would be dominant. This finding is potentially important, because receptor internalization has been associated with development of tolerance to opiate analgesics. In contrast, an R181C variant abolished both signaling and internalization in response to saturating doses of the hydrolysis-resistant enkephalin [D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO). Coexpression of the R181C and WT receptor led to independent trafficking of the 2 receptors. S42T and C192F variants showed a rightward shift in potency of both morphine and DAMGO, whereas the S147C variant displayed a subtle leftward shift in morphine potency. These data suggest that these and other such variants may have clinical relevance to opioid responsiveness to both endogenous ligands and exogenous drugs, and could influence a broad range of phenotypes, including ASUD, pain responses, and the development of tolerance to morphine.
Collapse
|
34
|
Involvement of exon 11-associated variants of the mu opioid receptor MOR-1 in heroin, but not morphine, actions. Proc Natl Acad Sci U S A 2009; 106:4917-22. [PMID: 19273844 DOI: 10.1073/pnas.0811586106] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heroin remains a major drug of abuse and is preferred by addicts over morphine. Like morphine, heroin has high affinity and selectivity for mu-receptors, but its residual analgesia in exon 1 MOR-1 knockout mice that do not respond to morphine suggests a different mechanism of action. MOR-1 splice variants lacking exon 1 have been observed in mice, humans, and rats, raising the possibility that they might be responsible for the residual heroin and morphine-6beta-glucuronide (M6G) analgesia in the exon 1 knockout mice. To test this possibility, we disrupted exon 11 of MOR-1, which eliminates all of the variants that do not contain exon 1. Morphine and methadone analgesia in the exon 11 knockout mouse was normal, but the analgesic actions of heroin, M6G, and fentanyl were markedly diminished in the radiant heat tail-flick and hot-plate assays. Similarly, the ability of M6G to inhibit gastrointestinal transit was greatly diminished in these exon 11 knockout mice, whereas the ability of morphine was unchanged. These findings identify receptors selectively involved with heroin and M6G actions and confirm the relevance of the exon 11-associated variants and raise important issues regarding the importance of atypical truncated G-protein-coupled receptors.
Collapse
|
35
|
Wu ZZ, Cai YQ, Pan HL. A functional link between T-type calcium channels and mu-opioid receptor expression in adult primary sensory neurons. J Neurochem 2009; 109:867-78. [PMID: 19250340 DOI: 10.1111/j.1471-4159.2009.06014.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mu-opioid receptor agonists have a preferential effect on nociception in adults but their analgesic effect is less selective in neonates. Here we presented our finding that the mu-opioid receptor agonists had no effect on high voltage-activated Ca(2+) channels (HVACCs) in adult dorsal root ganglion (DRG) neurons that exhibited a prominent T-type Ca(2+) current. We also determined the mechanisms underlying the mu-opioid agonists' lack of effect on HVACCs in these neurons. The mu-opioid agonist [D-Ala(2),N-Me-Phe(4),Gly-ol(5)]-enkephalin (DAMGO), morphine, and morphine 6-beta-D-glucuronide had no effect on either T-type or HVACC currents despite the presence of a large N-type Ca(2+) current in neurons with T-type Ca(2+) currents. DAMGO still had no effect on HVACC currents when T-type Ca(2+) channels were blocked in these neurons. However, intracellular dialysis of GTP-gamma-S to activate G proteins significantly attenuated HVACC currents. DRG neurons with T-type Ca(2+) currents showed little responses to capsaicin. Single-cell RT-PCR analysis revealed that the mu-opioid receptor mRNA was present only in adult DRG neurons lacking prominent T-type Ca(2+) currents. In the neonatal DRG, DAMGO inhibited HVACC currents in 31% neurons with T-type Ca(2+) currents. The mu-opioid receptor mRNA was detected in all neurons without T-type Ca(2+) currents and also in 28.6% of neurons with T-type Ca(2+) currents in the neonatal DRG. Our study provides novel information that adult DRG neurons with prominent T-type Ca(2+) currents do not express mu-opioid receptors. Expression of T-type Ca(2+) (Ca(V)3.2) channels and mu-opioid receptors may be developmentally co-regulated as some DRG neurons differentiate toward becoming nociceptive neurons.
Collapse
Affiliation(s)
- Zi-Zhen Wu
- Department of Anesthesiology and Perioperative Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | |
Collapse
|
36
|
Xu J, Xu M, Hurd YL, Pasternak GW, Pan YX. Isolation and characterization of new exon 11-associated N-terminal splice variants of the human mu opioid receptor gene. J Neurochem 2009; 108:962-72. [PMID: 19077058 PMCID: PMC2727151 DOI: 10.1111/j.1471-4159.2008.05833.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Alternative splicing of the mu opioid receptor genes to create multiple mu receptor subtypes has been demonstrated in animals and humans. Previously, we identified a number of C-terminal variants in mice, rats and human, followed by several N-terminal variants associated with a new upstream exon in mice (exon 11). Behavioral studies in exon 11 knockout mice suggest an important role for the exon 11 variants in the analgesic actions of heroin and morphine-6beta-glucuronide, but not morphine or methadone. We now have identified a homologous human exon 11 and three similar human exon 11-associated variants, suggesting conservation of exon 11 and its associated variants across species. hMOR-1i has an additional 93 amino acids at the tip of the N-terminus but is otherwise identical to hMOR-1. When expressed in Chinese hamster ovary cells, the additional 93 amino acids in hMOR-1i had little effect on opioid binding, but significantly altered agonist-induced G-protein activation. hMOR-1G1 and hMOR-1G2 predicted six transmembrane domain variants, similar to those seen in mice. The regional expression of these exon 11-associated variants, as determined by RT-PCR, varied markedly, implying region-specific alternative splicing. The presence of exon 11-associated variants in humans raises questions regarding their potential role in heroin and morphine-6beta-glucuronide actions in people as they do in mice.
Collapse
MESH Headings
- Alternative Splicing/genetics
- Animals
- CHO Cells
- Conserved Sequence/genetics
- Cricetinae
- Cricetulus
- DNA/chemistry
- Evolution, Molecular
- Exons/genetics
- Gene Expression
- Humans
- Mice
- Molecular Sequence Data
- Protein Isoforms/chemistry
- Protein Isoforms/genetics
- Protein Isoforms/isolation & purification
- Protein Structure, Tertiary/genetics
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/isolation & purification
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Species Specificity
Collapse
Affiliation(s)
- Jin Xu
- Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - Mingming Xu
- Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - Yasmin L. Hurd
- Departments of Psychiatry and Pharmacology & Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, USA
| | - Gavril W. Pasternak
- Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| | - Ying-Xian Pan
- Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
| |
Collapse
|
37
|
Oroszi G, Anton RF, O'Malley S, Swift R, Pettinati H, Couper D, Yuan Q, Goldman D. OPRM1 Asn40Asp predicts response to naltrexone treatment: a haplotype-based approach. Alcohol Clin Exp Res 2008; 33:383-93. [PMID: 19053977 DOI: 10.1111/j.1530-0277.2008.00846.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Individualized pharmacotherapy requires identification of genetic variants predictive of treatment response. In OPRM1, Asn40Asp has been reported to be predictive of response to naltrexone treatment. Nevertheless, the in vitro function of the polymorphism remains elusive and over 300 OPRM1 sequence variants have been identified to date. Therefore we used a haplotype-based approach to capture information of other genetic variants that might predict treatment response to naltrexone in the COMBINE Study. METHODS 5' nuclease genotyping assays (TaqMan) were applied for 10 SNPs. Five-locus haplotypes in 2 OPRM1 haplotype blocks were assigned to Caucasian participants. The relationship of the haplotypes to medication reflected by "good clinical outcome" was analyzed in 306 Caucasians treated without Combined Behavioral Intervention and with either naltrexone or placebo. RESULTS A significant haplotype by medication interaction (p = 0.03) was found in OPRM1 block 1. Naltrexone-treated alcoholics with haplotype AGCCC, the single haplotype carrying the Asp40 allele had the highest percent of good clinical outcome. When interaction of genotypes at each of the 5 loci comprising block 1 with medication was examined, only the Asn40/Asp40 and Asp40/Asp40 genotypes were found to significantly interact with naltrexone treatment. No haplotype by medication interaction was documented in OPRM1 block 2. CONCLUSIONS Our haplotype-based approach confirms that the single OPRM1 locus predictive of response to naltrexone treatment is Asn40Asp in exon 1. A substantial contribution of any other OPRM1 genetic variant to interindividual variations in response to naltrexone treatment (at least in terms of good clinical outcome) is not supported by our findings.
Collapse
Affiliation(s)
- Gabor Oroszi
- Center for Drug and Alcohol Programs, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Tanowitz M, Hislop JN, von Zastrow M. Alternative splicing determines the post-endocytic sorting fate of G-protein-coupled receptors. J Biol Chem 2008; 283:35614-21. [PMID: 18936093 DOI: 10.1074/jbc.m806588200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mu-type opioid receptors are physiologically important G-protein-coupled receptors that are generally thought to recycle after agonist-induced endocytosis. Here we show that several alternatively spliced receptor variants fail to do so efficiently because of splice-mediated removal of an endocytic sorting sequence that is present specifically in the MOR1 variant. All of the recycling-impaired receptor variants were found to undergo proteolytic down-regulation more rapidly than MOR1, irrespective of moderate differences in endocytic rate, indicating that alternative splicing plays a specific role in distinguishing the trafficking itinerary of receptors after endocytosis. The recycling-impaired MOR1B variant was similar to MOR1 in its ability to mediate opioid-dependent inhibition of adenylyl cyclase, and to undergo opioid-induced desensitization in intact cells. Functional recovery (resensitization) of MOR1B-mediated cellular responsiveness after opioid removal, however, was significantly impaired (4-fold reduction in rate) compared with MOR1. To our knowledge the present results are the first to establish a role of alternative RNA processing in specifying the post-endocytic sorting of G-protein-coupled receptors between divergent and functionally distinct membrane pathways.
Collapse
Affiliation(s)
- Michael Tanowitz
- Department of Psychiatry, University of California, San Francisco, California 94158-2140, USA
| | | | | |
Collapse
|
39
|
Effects of trichostatin A on neuronal mu-opioid receptor gene expression. Brain Res 2008; 1246:1-10. [PMID: 18950606 DOI: 10.1016/j.brainres.2008.09.083] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 09/17/2008] [Accepted: 09/19/2008] [Indexed: 11/21/2022]
Abstract
In this study, we determined the effects of a histone deacetylase (HDAC) inhibitor, trichostatin A (TSA), on neuronal mu-opioid receptor (MOR) gene expression using human neuronal NMB cells, endogenously expressing MOR. Recruitment of two classes of HDAC, HDAC1 and HDAC2, to MOR promoter region in situ was detected via chromatin immunoprecipitation (ChIP) analysis with NMB cells. Functional analysis using the luciferase reporter gene system showed that TSA induced an approximately 3-fold increase of the promoter activity as compared to the vehicle treated group. Mutation analysis demonstrated that TSA response was mediated by both dsDNA (Sp1/Sp3 binding site) and ssDNA (PolyC binding protein1, PCBP, binding site) elements located in mouse MOR proximal core promoter region, further suggesting the functional importance of this cis-element, which shows high sequence homology between human and mouse MOR genes. ChIP analysis further suggested that TSA enhanced the recruitment of Sp1/Sp3 and PCBP to the promoter region, whereas no significant changes of total proteins were observed in response to TSA using Western blot analysis. Moreover, confocal images showed TSA-induced nuclear hot spots of endogenous PCBP in neuronal cells, whereas no obvious nuclear PCBP hotspot was observed in vehicle treated cells. Taken together, these results suggested that TSA enhanced neuronal MOR gene expression at the transcriptional level. RT-PCR analysis further revealed that TSA also decreased the steady-state level of MOR mRNA in a time-dependent manner by enhancing its instability. Thus, data suggest that TSA, an epigenetic regulator, affects neuronal MOR gene expression at both transcriptional and post-transcriptional levels.
Collapse
|
40
|
Fichna J, Staniszewska R, Poels J, Vanden Broeck J, Janecka A. ?-Opioid Receptor Ligands Lack Receptor Subtype Selectivity in the Aequorin Luminescence-based Calcium Assay. Chem Biol Drug Des 2007; 70:247-53. [PMID: 17718719 DOI: 10.1111/j.1747-0285.2007.00550.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of the present study was to characterize the binding selectivity of the mu-opioid receptor ligands, endomorphin-1, endomorphin-2, and DAMGO, in the in vitro functional assay, based on the changes in intracellular calcium levels. For the experiments Chinese hamster ovary cells, stably expressing human mu-receptor, were used. The mu-agonist-induced calcium responses were significantly inhibited by naloxone, an opioid antagonist with high preference for the mu-opioid receptors. Naloxonazine, a mu1-non-peptide antagonist, inhibited the effect of all tested mu-agonists. However, there was no significant difference in the antagonist effect of naloxonazine on the calcium response induced by mu1- (endomorphin-2) and mu2-agonists (endomorphin-1, DAMGO). [D-Pro2]endomorphin-1 and [D-Pro2]endomorphin-2, putative peptide mu2- and mu1-antagonists, respectively, which had been shown in vivo to inhibit the antinociception induced by mu-agonists, produced no inhibitory effect in our in vitro experiments. Our results demonstrated that there is only one population of the mu-opioid receptors expressed in the Chinese hamster ovary cells. We suggest that the mu-opioid receptors form a homogenous population in the in vitro systems. However, the existence of mu-receptor subtypes in vivo is still pharmacologically possible.
Collapse
Affiliation(s)
- Jakub Fichna
- Laboratory of Biomolecular Chemistry, Institute of Biomedicinal Chemistry, Medical University, Mazowiecka 6/8, 92-215 Lodz, Poland
| | | | | | | | | |
Collapse
|
41
|
Characterizing exons 11 and 1 promoters of the mu opioid receptor (Oprm) gene in transgenic mice. BMC Mol Biol 2006; 7:41. [PMID: 17101047 PMCID: PMC1657025 DOI: 10.1186/1471-2199-7-41] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Accepted: 11/13/2006] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The complexity of the mouse mu opioid receptor (Oprm) gene was demonstrated by the identification of multiple alternatively spliced variants and promoters. Our previous studies have identified a novel promoter, exon 11 (E11) promoter, in the mouse Oprm gene. The E11 promoter is located approximately 10 kb upstream of the exon 1 (E1) promoter. The E11 promoter controls the expression of nine splice variants in the mouse Oprm gene. Distinguished from the TATA-less E1 promoter, the E11 promoter resembles a typical TATA-containing eukaryote class II promoter. The aim of this study is to further characterize the E11 and E1 promoters in vivo using a transgenic mouse model. RESULTS We constructed a approximately 20 kb transgenic construct in which a 3.7 kb E11 promoter region and an 8.9 kb E1 promoter region controlled expression of tau/LacZ and tau/GFP reporters, respectively. The construct was used to establish a transgenic mouse line. The expression of the reporter mRNAs, determined by a RT-PCR approach, in the transgenic mice during embryonic development displayed a temporal pattern similar to that of the endogenous promoters. X-gal staining for tau/LacZ reporter and GFP imaging for tau/GFP reporter showed that the transgenic E11 and E1 promoters were widely expressed in various regions of the central nervous system (CNS). The distribution of tau/GFP reporter in the CNS was similar to that of MOR-1-like immunoreactivity using an exon 4-specific antibody. However, differential expression of both promoters was observed in some CNS regions such as the hippocampus and substantia nigra, suggesting that the E11 and E1 promoters were regulated differently in these regions. CONCLUSION We have generated a transgenic mouse line to study the E11 and E1 promoters in vivo using tau/LacZ and tau/GFP reporters. The reasonable relevance of the transgenic model was demonstrated by the temporal and spatial expression of the transgenes as compared to those of the endogenous transcripts. We believe that these transgenic mice will provide a useful model for further characterizing the E11 and E1 promoter in vivo under different physiological and pathological circumstances such as chronic opioid treatment and chronic pain models.
Collapse
|
42
|
Berry AM, Flock KE, Loh HH, Ko JL. Molecular basis of cellular localization of poly C binding protein 1 in neuronal cells. Biochem Biophys Res Commun 2006; 349:1378-86. [PMID: 16979592 PMCID: PMC1618817 DOI: 10.1016/j.bbrc.2006.09.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Accepted: 09/01/2006] [Indexed: 11/26/2022]
Abstract
Poly C binding protein 1 (PCBP) is involved in the transcriptional regulation of neuronal mu-opioid receptor gene. In this study, we examined the molecular basis of PCBP cellular/nuclear localization in neuronal cells using EGFP fusion protein. PCBP, containing three KH domains and a variable domain, distributed in cytoplasm and nucleus with a preferential nuclear expression. Domain-deletional analyses suggested the requirement of variable and KH3 domains for strong PCBP nuclear expression. Within the nucleus, a low nucleolar PCBP expression was observed, and PCBP variable domain contributed to this restricted nucleolar expression. Furthermore, the punctate nuclear pattern of PCBP was correlated to its single-stranded (ss) DNA binding ability, with both requiring cooperativity of at least three sequential domains. Collectively, certain PCBP domains thus govern its nuclear distribution and transcriptional regulatory activity in the nucleus of neurons, whereas the low nucleolar expression implicates the disengagement of PCBP in the ribosomal RNA synthesis.
Collapse
Affiliation(s)
- Andrea M Berry
- Department of Biology, Seton Hall University, 208 McNulty Hall, 400 South Orange Avenue, South Orange, NJ 07079, USA
| | | | | | | |
Collapse
|
43
|
Malik AK, Flock KE, Godavarthi CL, Loh HH, Ko JL. Molecular basis underlying the poly C binding protein 1 as a regulator of the proximal promoter of mouse mu-opioid receptor gene. Brain Res 2006; 1112:33-45. [PMID: 16904079 DOI: 10.1016/j.brainres.2006.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 06/07/2006] [Accepted: 07/05/2006] [Indexed: 11/19/2022]
Abstract
Previous studies showed poly C binding protein 1 (PCBP) participating in the mu-opioid receptor (MOR) gene regulation via binding to a single-stranded (ss) DNA element. In this report, we therefore investigate the molecular basis of PCBP regulating the MOR gene expression. Various truncated PCBPs, including one domain (KH1, KH2, variable or KH3), two- (K12, K2v or Kv3) or three-sequential domains (K12v or K2v3), were constructed. The MOR ssDNA binding abilities of these truncated PCBPs were examined using electrophoretic mobility shift assay (EMSA). KH1 domain possessed a strong MOR ssDNA binding activity. Variable domain displayed no binding, and KH2 or KH3 domain possessed a weak MOR ssDNA binding activity. Binding of two-domain PCBPs indicated an additive effect of two-domain combinations. Interestingly, K2v3, a three-domain PCBP, displayed as strong ssDNA binding as that of K12v, suggesting synergism of KH2, KH3 and variable domains for the binding activity. Functional analysis demonstrated one-domain PCBPs exhibiting no transactivation on the MOR proximal promoter. Two-domain PCBPs displayed approximately 20% activity, while three-domain PCBPs displayed 70%-85% of full-length PCBP activity. Taken together, these results suggested that no single domain possessed sufficient functional activity to serve as an independent transactivation domain, and the combination of three sequential domains was necessary for its optimal activity to activate the MOR proximal promoter. In summary, our data suggested that cooperativity of three sequential domains is essential for PCBP functioning as a MOR gene regulator. Various ways in which this cooperativity could occur are discussed.
Collapse
MESH Headings
- Animals
- Base Sequence
- Carrier Proteins/physiology
- Cell Line, Tumor
- DNA-Binding Proteins
- Electrophoretic Mobility Shift Assay/methods
- Gene Expression Regulation/physiology
- Methionine/metabolism
- Mice
- Neuroblastoma
- Phosphorus Isotopes/metabolism
- Promoter Regions, Genetic/physiology
- Protein Binding/drug effects
- Protein Binding/physiology
- Protein Structure, Tertiary/physiology
- RNA, Messenger/metabolism
- RNA-Binding Proteins
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Regulatory Sequences, Nucleic Acid
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Transcription, Genetic
- Transfection/methods
Collapse
Affiliation(s)
- Adnan K Malik
- Department of Biology, Seton Hall University, 208 McNulty Hall, 400 South Orange Ave. South Orange, NJ 07079, USA
| | | | | | | | | |
Collapse
|
44
|
Milo S, Ansonoff M, King M, Rossi GC, Zuckerman A, Pintar J, Pasternak GW. Codeine and 6-Acetylcodeine Analgesia in Mice. Cell Mol Neurobiol 2006; 26:1011-9. [PMID: 16868817 DOI: 10.1007/s10571-006-9101-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Accepted: 09/26/2005] [Indexed: 11/28/2022]
Abstract
1. Acetylation of morphine at the 6-position changes its pharmacology. To see if similar changes are seen with codeine, we examined the analgesic actions of codeine and 6-acetylcodeine. 2. Like codeine, 6-acetylcodeine is an effective analgesic systemically, supraspinally and spinally, with a potency approximately a third that of codeine. 3. The sensitivity of 6-acetylcodeine analgesia to the mu-selective antagonists beta-FNA and naloxonazine confirmed its classification as a mu opioid. However, it differed from the other mu analgesics in other paradigms. 4. Antisense mapping revealed the sensitivity of 6-acetylcodeine to probes targeting exons 1 and 2 of the mu opioid receptor gene (Oprm), a profile distinct from either codeine or morphine. Although heroin analgesia also is sensitive to antisense targeting exons 1 and 2, heroin analgesia also is sensitive to the antagonist 3-O-methylnaltrexone, while 6-acetylcodeine analgesia is not. 5. Thus, 6-acetylcodeine is an effective mu opioid analgesic with a distinct pharmacological profile.
Collapse
Affiliation(s)
- Steven Milo
- Laboratory of Molecular Neuropharmacology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, New York 10021, USA
| | | | | | | | | | | | | |
Collapse
|
45
|
Zhang Y, Pan YX, Kolesnikov Y, Pasternak GW. Immunohistochemical labeling of the mu opioid receptor carboxy terminal splice variant mMOR-1B4 in the mouse central nervous system. Brain Res 2006; 1099:33-43. [PMID: 16793025 DOI: 10.1016/j.brainres.2006.04.133] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 04/14/2006] [Accepted: 04/17/2006] [Indexed: 12/21/2022]
Abstract
The mu opioid receptor gene Oprm is alternatively spliced into many variants, providing for the multiplicity of mu opioid receptor subtypes. One of the mouse variants, mMOR-1B4, is unique in that it displays high affinity towards a wide range of mu opioid receptor antagonists, but poor affinity towards most classical mu opioid agonists. The present study examined the immunohistochemical distribution of the mMOR-1B4 variant in mouse brain and spinal cord. mMOR-1B4-like immunoreactivity (mMOR-1B4-LI) was enriched in many regions of the brain, spinal cord and in the dorsal root ganglia. Some of the structures showing prominent mMOR-1B4-LI include the olfactory bulb, cerebral cortex, bed nucleus of stria terminalis, hippocampus, habenular nucleus, amygdala, thalamus, hypothalamus, medium eminence, substantia nigra, ventral tegmental area, oculomotor nucleus, red nucleus, raphe nuclei, periaqueductal gray, locus coeruleus, trigeminal nucleus, reticular formation, area postrema and Purkinje cell layer and deep nuclei of cerebellum. mMOR-1B4-LI was present in afferent neurons of the dorsal root ganglia and their projecting fibers into the superficial laminae of the spinal dorsal horn. Some motor neurons in the anterior horn of the spinal cord also were immunopositive. The overall distribution of mMOR-1B4-LI in the central nervous system is distinguishable from previously characterized variants such as MOR-1-LI, MOR-1C-LI and exon-11-LI. These studies provide evidence for the region- and neuron-specific processing of the Oprm gene and support the possibility of functional differences among the variants.
Collapse
Affiliation(s)
- Yahong Zhang
- Laboratory of Molecular Neuropharmacology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | | | | | | |
Collapse
|
46
|
Mahurter L, Garceau C, Marino J, Schmidhammer H, Tóth G, Pasternak GW. Separation of binding affinity and intrinsic activity of the potent mu-opioid 14-methoxymetopon. J Pharmacol Exp Ther 2006; 319:247-53. [PMID: 16801454 DOI: 10.1124/jpet.106.105395] [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: 11/22/2022] Open
Abstract
Receptor binding studies of 5,14-O-dimethyloxymorphone (14-methoxymetopon) in brain membranes have established its high affinity for mu-binding sites, but its analgesic potency far exceeds the modest increase in binding affinity relative to other opioids. The current study has established the selectivity of [(3)H]14-methoxymetopon for mu sites in calf striatal membranes and for a number of full-length splice variants of the cloned murine mu-opioid receptor 1 (mMOR-1) in transfected cell lines. The binding affinity of [(3)H]14-methoxymetopon for the variants expressed in Chinese hamster ovary cells was quite high, with K(D) values around 0.2 nM for all of the variants with the exception of mMOR-1F (K(D) of 1.2 nM). The affinity for most of the expressed variants was greater than that seen in the brain membranes (K(D) of 0.99 nM). Functionally, in guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding assays with the MOR-1 variants, 14-methoxymetopon and the mu-opioid peptide [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) showed similar efficacies, as determined by maximal stimulation, but 14-methoxymetopon was up to 65-fold more potent than DAMGO. The greatest difference was seen with mMOR-1E and the least with mMOR-1C, which displayed only a 10-fold difference. These potency differences in the stimulation of [(35)S]GTPgammaS binding far exceeded the differences in binding affinity. The differences between 14-methoxymetopon and DAMGO remained after normalizing the potency shifts based upon receptor binding affinities and varied from 1.2-fold with mMOR-1C to 21-fold for mMOR-1 and 42-fold with mMOR-1F. Thus, 14-methoxymetopon is a potent agonist against all of the mMOR-1 splice variants, but its potency ranged widely despite similar binding affinities for most of the variants and may give insight into its unusual pharmacological profile.
Collapse
Affiliation(s)
- Loriann Mahurter
- Laboratory of Molecular Neuropharmacology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021, USA
| | | | | | | | | | | |
Collapse
|
47
|
Choi HS, Kim CS, Hwang CK, Song KY, Wang W, Qiu Y, Law PY, Wei LN, Loh HH. The opioid ligand binding of human μ-opioid receptor is modulated by novel splice variants of the receptor. Biochem Biophys Res Commun 2006; 343:1132-40. [PMID: 16580639 DOI: 10.1016/j.bbrc.2006.03.084] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 03/07/2006] [Indexed: 10/24/2022]
Abstract
The pharmacological actions of morphine and morphine-like drugs, such as heroin, mediate primarily through the mu-opioid receptor (MOR). It has been proposed that the functional diversity of MOR may be related to alternative splicing of the MOR gene. Although a number of MOR mRNA splice variants have been reported, their biological function has been controversial. In this study, two novel splice variants of the human MOR gene were discovered. Splice variants 1 and 2 (here called the SV1 and SV2) retain different portions of intron I. In vitro translation of SV1 and SV2 produced proteins with the predicted molecular weights. The splice variant proteins were identical to the wild-type MOR-1 up to the first transmembrane domains, but were different after the first intracellular loop domains. SV1 and SV2 of hMOR were present in human neuroblastoma NMB cells and human whole brain confirmed by RT-PCR. In a receptor binding assay, cells expressing the SV1 and SV2 do not exhibit binding to [(3)H]diprenorphine. The formations of MOR.SV1 and MOR.SV2 heterodimers were demonstrated by co-immunoprecipitation and bioluminescence resonance energy transfer between MOR and splice variants. Co-transfection of MOR-GFP and SV-DsRed gene showed that MOR and SV protein co-localized at the cytoplasmic membrane. In NMB cells expressing human MOR gene, transfection of SV1 or SV2 reduced binding activity of the endogenous MOR. These data support a potential role of SV1 and SV2 proteins as possible biological modulator of human mu-opioid receptor.
Collapse
Affiliation(s)
- Hack Sun Choi
- Department of Pharmacology, Medical School, University of Minnesota, Minneapolis, MN 55455, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Zhang H, Luo X, Kranzler HR, Lappalainen J, Yang BZ, Krupitsky E, Zvartau E, Gelernter J. Association between two mu-opioid receptor gene (OPRM1) haplotype blocks and drug or alcohol dependence. Hum Mol Genet 2006; 15:807-19. [PMID: 16476706 PMCID: PMC3164878 DOI: 10.1093/hmg/ddl024] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We examined 13 single nucleotide polymorphisms (SNPs) spanning the coding region of the mu-opioid receptor gene (OPRM1), among 382 European Americans (EAs) affected with substance dependence [alcohol dependence (AD) and/or drug dependence (DD)] and 338 EA healthy controls. These SNPs delineated two haplotype blocks. Genotype distributions for all SNPs were in Hardy-Weinberg equilibrium (HWE) in controls, but in cases, four SNPs in Block I and three SNPs in Block II showed deviation from HWE. Significant differences were found between cases and controls in allele and/or genotype frequencies for six SNPs in Block I and two SNPs in Block II. Association of SNP4 in Block I with DD (allele: P=0.004), SNP5 in Block I with AD and DD (allele: P< or =0.005 for both) and two SNPs in Block II with AD (SNP11 genotype: P=0.002; SNP12 genotype: P=0.001) were significant after correction for multiple testing. Frequency distributions of haplotypes (constructed by five tag SNPs) differed significantly for cases and controls (P<0.001 for both AD and DD). Logistic regression analyses confirmed the association between OPRM1 variants and substance dependence, when sex and age of subjects and alleles, genotypes, haplotypes or diplotypes of five tag SNPs were considered. Population structure analyses excluded population stratification artifact. Additional supporting evidence for association between OPRM1 and AD was obtained in a smaller Russian sample (247 cases and 100 controls). These findings suggest that OPRM1 intronic variants play a role in susceptibility to AD and DD in populations of European ancestry.
Collapse
Affiliation(s)
- Huiping Zhang
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- VA Connecticut Healthcare System, Psychiatry 116A2, 950 Campbell Avenue, West Haven, CT 06516, USA
| | - Xingguang Luo
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- VA Connecticut Healthcare System, Psychiatry 116A2, 950 Campbell Avenue, West Haven, CT 06516, USA
| | - Henry R. Kranzler
- Department of Psychiatry, University of Connecticut School of Medicine, Farmington, CT, USA
| | - Jaakko Lappalainen
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- VA Connecticut Healthcare System, Psychiatry 116A2, 950 Campbell Avenue, West Haven, CT 06516, USA
| | - Bao-Zhu Yang
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- VA Connecticut Healthcare System, Psychiatry 116A2, 950 Campbell Avenue, West Haven, CT 06516, USA
| | - Evgeny Krupitsky
- St Petersburg State Pavlov Medical University, St Petersburg, Russia
| | - Edwin Zvartau
- St Petersburg State Pavlov Medical University, St Petersburg, Russia
| | - Joel Gelernter
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- VA Connecticut Healthcare System, Psychiatry 116A2, 950 Campbell Avenue, West Haven, CT 06516, USA
- To whom correspondence should be addressed. Tel: +1 2039325711 ext. 3599; Fax: +1 2039373897;
| |
Collapse
|
49
|
Pan YX. Diversity and Complexity of the Mu Opioid Receptor Gene: Alternative Pre-mRNA Splicing and Promoters. DNA Cell Biol 2005; 24:736-50. [PMID: 16274294 DOI: 10.1089/dna.2005.24.736] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mu opioid receptors play an important role in mediating the actions of a class of opioids including morphine and heroin. Binding and pharmacological studies have proposed several mu opioid receptor subtypes: mu(1), mu(2), and morphine-6beta-glucuronide (M6G). The cloning of a mu opioid receptor, MOR-1, has provided an invaluable tool to explore pharmacological and physiological functions of mu opioid receptors at the molecular level. However, only one mu opioid receptor (Oprm) gene has been isolated. Alternative pre-mRNA splicing has been proposed as a molecular explanation for the existence of pharmacologically identified subtypes. In recent years, we have extensively investigated alternative splicing of the Oprm gene, particularly of the mouse Oprm gene. So far we have identified 25 splice variants from the mouse Oprm gene, which are controlled by two diverse promoters, eight splice variants from the rat Oprm gene, and 11 splice variants from the human Oprm gene. Diversity and complexity of the Oprm gene was further demonstrated by functional differences in agonist-induced G protein activation, adenylyl cyclase activity, and receptor internalization among carboxyl terminal variants. This review summarizes these recent results and provides a new perspective on understanding and exploring complex opioid actions in animals and humans.
Collapse
Affiliation(s)
- Ying-Xian Pan
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
| |
Collapse
|
50
|
Pan L, Xu J, Yu R, Xu MM, Pan YX, Pasternak GW. Identification and characterization of six new alternatively spliced variants of the human mu opioid receptor gene, Oprm. Neuroscience 2005; 133:209-20. [PMID: 15893644 DOI: 10.1016/j.neuroscience.2004.12.033] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 12/09/2004] [Accepted: 12/12/2004] [Indexed: 10/25/2022]
Abstract
The mu opioid receptor plays an important role in mediating the actions of morphine and morphine-like drugs. Receptor binding and a wide range of pharmacological studies have proposed several mu receptor subtypes, but only one mu opioid receptor (Oprm) gene has been isolated. Like the mouse and rat, the human Oprm gene undergoes alternative splicing. In the present studies, we have identified and characterized six new splice variants from the human Oprm gene using a reverse transcription-polymerase chain reaction strategy, yielding a total of 10 human splice variants of the mu opioid receptor MOR-1. All the variants identified contained exons 1, 2 and 3, but differed from MOR-1 itself and each other by splicing downstream from exon 3, resulting in different amino acid sequences. Northern blot analysis demonstrated expression of the variant mRNAs. Receptor binding assays established that these variants belonged to the mu opioid receptor family with limited differences in mu opioid ligand affinities and selectivity. However, adenylyl cyclase and [35S]GTPgammaS binding assays revealed major differences in both potency and efficacy among these variants. The dissociation between binding affinity, potency and efficacy for the opioids among these variants may provide insights into the wide range of opioid responses among these agents observed clinically and opens new avenues in designing selective drugs based upon their efficacy and potency rather simple binding affinity.
Collapse
Affiliation(s)
- L Pan
- Laboratory of Molecular Neuropharmacology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
| | | | | | | | | | | |
Collapse
|