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Liu S, Kang WJ, Abrimian A, Xu J, Cartegni L, Majumdar S, Hesketh P, Bekker A, Pan YX. Alternative Pre-mRNA Splicing of the Mu Opioid Receptor Gene, OPRM1: Insight into Complex Mu Opioid Actions. Biomolecules 2021; 11:biom11101525. [PMID: 34680158 PMCID: PMC8534031 DOI: 10.3390/biom11101525] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/11/2021] [Accepted: 10/11/2021] [Indexed: 12/03/2022] Open
Abstract
Most opioid analgesics used clinically, including morphine and fentanyl, as well as the recreational drug heroin, act primarily through the mu opioid receptor, a class A Rhodopsin-like G protein-coupled receptor (GPCR). The single-copy mu opioid receptor gene, OPRM1, undergoes extensive alternative splicing, creating multiple splice variants or isoforms via a variety of alternative splicing events. These OPRM1 splice variants can be categorized into three major types based on the receptor structure: (1) full-length 7 transmembrane (TM) C-terminal variants; (2) truncated 6TM variants; and (3) single TM variants. Increasing evidence suggests that these OPRM1 splice variants are pharmacologically important in mediating the distinct actions of various mu opioids. More importantly, the OPRM1 variants can be targeted for development of novel opioid analgesics that are potent against multiple types of pain, but devoid of many side-effects associated with traditional opiates. In this review, we provide an overview of OPRM1 alternative splicing and its functional relevance in opioid pharmacology.
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Affiliation(s)
- Shan Liu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Wen-Jia Kang
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Anna Abrimian
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Jin Xu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Luca Cartegni
- Department of Chemical Biology, Ernest Mario School of Pharmacy Rutgers University, Piscataway, NJ 08854, USA;
| | - Susruta Majumdar
- Center for Clinical Pharmacology, University of Health Sciences & Pharmacy and Washington University School of Medicine, St. Louis, MO 63110, USA;
| | - Patrick Hesketh
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Alex Bekker
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
| | - Ying-Xian Pan
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; (S.L.); (W.-J.K.); (A.A.); (J.X.); (P.H.); (A.B.)
- Correspondence: ; Tel.: +1-973-972-3213
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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.
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Affiliation(s)
- Gavril W Pasternak
- Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
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Identification of candidate genes and gene networks specifically associated with analgesic tolerance to morphine. J Neurosci 2009; 29:5295-307. [PMID: 19386926 DOI: 10.1523/jneurosci.4020-08.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Chronic morphine administration may alter the expression of hundreds to thousands of genes. However, only a subset of these genes is likely involved in analgesic tolerance. In this report, we used a behavior genetics strategy to identify candidate genes specifically linked to the development of morphine tolerance. Two inbred genotypes [C57BL/6J (B6), DBA2/J (D2)] and two reciprocal congenic genotypes (B6D2, D2B6) with the proximal region of chromosome 10 (Chr10) introgressed into opposing backgrounds served as the behavior genetic filter. Tolerance after therapeutically relevant doses of morphine developed most rapidly in the B6 followed by the B6D2 genotype and did not develop in the D2 mice and only slightly in the D2B6 animals indicating a strong influence of the proximal region of Chr10 in the development of tolerance. Gene expression profiling and pattern matching identified 64, 53, 86, and 123 predisposition genes and 81, 96, 106, and 82 tolerance genes in the periaqueductal gray (PAG), prefrontal cortex, temporal lobe, and ventral striatum, respectively. A potential gene network was identified in the PAG in which 19 of the 34 genes were strongly associated with tolerance. Eleven of the network genes were found to reside in quantitative trait loci previously associated with morphine-related behaviors, whereas seven were predictive of tolerance (morphine-naive condition). Overall, the genes modified by chronic morphine administration show a strong presence in canonical pathways representative of neuroadaptation. A potentially significant role for the micro-RNA and epigenetic mechanisms in response to chronic administration of pharmacologically relevant doses of morphine was highlighted by candidate genes Dicer and H19.
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Association of morphine-induced antinociception with variations in the 5′ flanking and 3′ untranslated regions of the μ opioid receptor gene in 10 inbred mouse strains. Pharmacogenet Genomics 2008; 18:927-36. [DOI: 10.1097/fpc.0b013e32830d0b9e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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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.
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Han W, Kasai S, Hata H, Takahashi T, Takamatsu Y, Yamamoto H, Uhl GR, Sora I, Ikeda K. Intracisternal A-particle element in the 3' noncoding region of the mu-opioid receptor gene in CXBK mice: a new genetic mechanism underlying differences in opioid sensitivity. Pharmacogenet Genomics 2006; 16:451-60. [PMID: 16708053 DOI: 10.1097/01.fpc.0000215072.36965.8d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES CXBK mice, recombinant inbred mice derived from C57BL/6By and BALB/cBy progenitors, display reduced morphine-induced analgesia. Earlier we reported that CXBK mice expressed a reduced amount of the major transcript, MOR-1 mRNA, of the mu-opioid receptor gene. The CXBK MOR-1 mRNA contains a normal coding region and an abnormally long untranslated region. METHODS AND RESULTS To identify the nucleotide-sequence difference between the CXBK MOR-1 mRNA and that of the progenitors, we first characterized the 3' untranslated region of the MOR-1 mRNA, which was largely unknown. A 3' rapid amplification of cDNA ends-PCR analysis revealed that the 3' untranslated region of the C57BL/6By MOR-1 mRNA was 10 181 nucleotides transcribed from an exon. Next, we compared the MOR-1 genes in C57BL/6By, CXBK, and BALB/cBy mice, and found a 5293 nucleotide insertion only in CXBK mice. The inserted sequence was a variant of the intracisternal A-particle elements that exist in the mouse genome at approximately 1000 sites. Reverse transcription-PCR analyses revealed that the intracisternal A-particle element was transcribed as a part of the CXBK MOR-1 mRNA. No other differences were found in the MOR-1 mRNA between CXBK and BALB/cBy mice, whereas 100 nucleotides differed between C57BL/6By and CXBK mice aside from the intracisternal A-particle insertion. Finally, CXBK mice displayed reduced morphine responses compared with BALB/cBy mice. CONCLUSIONS Our data suggest that differences in the MOR-1 3' untranslated region appear to cause the CXBK phenotype. This genetic mechanism underlying the CXBK phenotype may provide good insight into the possible genetic mechanisms underlying individual differences in opioid sensitivity in humans.
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MESH Headings
- 3' Untranslated Regions
- Analgesics, Opioid/pharmacology
- Animals
- Base Sequence
- Crosses, Genetic
- Drug Resistance/genetics
- Genes, Intracisternal A-Particle
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Molecular Sequence Data
- Morphine/pharmacology
- RNA, Messenger/chemistry
- Receptors, Opioid, mu/genetics
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Affiliation(s)
- Wenhua Han
- Division of Psychobiology, Tokyo Institute of Psychiatry, Tokyo, Japan
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7
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Doyle GA, Rebecca Sheng X, Lin SSJ, Press DM, Grice DE, Buono RJ, Ferraro TN, Berrettini WH. Identification of three mouse mu-opioid receptor (MOR) gene (Oprm1) splice variants containing a newly identified alternatively spliced exon. Gene 2006; 388:135-47. [PMID: 17156941 DOI: 10.1016/j.gene.2006.10.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 10/24/2006] [Accepted: 10/28/2006] [Indexed: 12/01/2022]
Abstract
The mouse mu-opioid receptor gene, Oprm1, is recognized currently to contain 17 alternatively spliced exons that generate 24 splice variants encoding at least 11 morphine-binding isoforms of the receptor. Here, we identify three new MOR splice variants that contain a previously undescribed exon, exon 18, and provide evidence that they are expressed in two mouse strains. The transcripts containing the newly identified exon 18 encode two new putative mu-opioid receptor isoforms, MOR-1V and MOR-1W. In mouse Oprm1, exon 18 is located between the described exons 10 and 6. Exon 18 appears to be conserved in the rat genome between exons 4 and 7. A BLAST search of the non-redundant GenBank database suggests that human OPRM1 may also contain exon 18. Analysis of mouse brain mRNA by RT-PCR suggests that MOR-1Vii transcripts are expressed in all areas of the brain analyzed, whereas expression of MOR-1Vi transcripts was restricted to thalamus and striatum. MOR-1W transcripts are expressed most highly in the hypothalamus, thalamus and striatum. In summary, we have identified three brain expressed, alternatively spliced mouse MOR splice variants containing a novel exon and encoding new putative MOR isoforms, MOR-1V and MOR-1W.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- Brain/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- Exons/genetics
- Gene Expression
- Male
- Mice/genetics
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Models, Genetic
- Molecular Sequence Data
- Phosphorylation
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
- Species Specificity
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Affiliation(s)
- Glenn A Doyle
- The Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
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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.
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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
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Affiliation(s)
- Adnan K Malik
- Department of Biology, Seton Hall University, 208 McNulty Hall, 400 South Orange Ave. South Orange, NJ 07079, USA
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9
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Doyle GA, Sheng XR, Schwebel CL, Ferraro TN, Berrettini WH, Buono RJ. Identification and functional significance of polymorphisms in the μ-opioid receptor gene (Oprm) promoter of C57BL/6 and DBA/2 mice. Neurosci Res 2006; 55:244-54. [PMID: 16644048 DOI: 10.1016/j.neures.2006.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 03/03/2006] [Accepted: 03/13/2006] [Indexed: 11/30/2022]
Abstract
C57BL/6J and DBA/2J mice demonstrate differences in morphine preference when tested in a two-bottle choice paradigm. Quantitative trait loci (QTL) mapping suggested the proximal region of chromosome 10 was responsible for 41% of the observed genetic variance. The mu-opioid receptor (MOR) gene (Oprm) maps to this region and is a prime candidate for explaining the QTL. We hypothesized that variations in Oprm between these strains are responsible for differences in morphine preference. We identify five single nucleotide polymorphisms (SNPs) in the Oprm promoter; three within or near putative transcription factor binding sites. Promoter fragments were amplified from genomic DNA by polymerase chain reaction (PCR) and subcloned into luciferase reporter vectors. A significant difference in basal Oprm promoter activity was seen with C57BL/6 and DBA/2 approximately 1675 constructs in MOR-positive BE(2)-C cells, but not in MOR-negative Neuro-2a cells. In BE(2)-C cells, average DBA/2 approximately 1675 construct activity was 1.3-2.0x greater than average C57BL/6 activity suggesting that the SNPs might alter MOR expression in these two mouse strains. Significant differences in promoter activities between the two cell lines suggest that cell-type-specific transcription factors are involved. No significant differences in construct activity were found between untreated and morphine-treated BE(2)-C or Neuro-2a cells, suggesting that morphine does not regulate transcription of Oprm.
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Affiliation(s)
- Glenn A Doyle
- The Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, United States.
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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.
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Affiliation(s)
- Ying-Xian Pan
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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11
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Ko JL, Loh HH. Poly C binding protein, a single-stranded DNA binding protein, regulates mouse mu-opioid receptor gene expression. J Neurochem 2005; 93:749-61. [PMID: 15836633 DOI: 10.1111/j.1471-4159.2005.03089.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previously, a single-stranded (ss) DNA element, polypyrimidine (PPy) element, was found to be important for the proximal promoter activity of mouse micro-opioid receptor (MOR) gene in a neuronal cell model. In this study, we identified the presence of unknown ssDNA binding proteins specifically bound to MOR ssPPy element in the mouse brain, implicating the physiological significance of these proteins. To identify the ssDNA binding proteins, yeast one-hybrid system with PPy element as the bait was used to screen a mouse brain cDNA library. The clone encoding poly C binding protein (PCBP) was obtained. Its full-length cDNA sequence and protein with molecular weight approximately 38 kDa were confirmed. Electrophoretic mobility shift analysis (EMSA) revealed that PCBP bound to ssPPy element, but not doubled-stranded, in a sequence-specific manner. EMSA with anti-PCBP antibody demonstrated the involvement of PCBP in MOR ssPPy/proteins complexes of mouse brain and MOR expressing neuroblastoma NMB cells. Functional analysis showed that PCBP trans-activated MOR promoter as well as a heterologous promoter containing MOR PPy element. Importantly, ectopic expression of PCBP in NMB cells up-regulated the expression level of endogenous MOR gene in vivo in a dose-dependent manner. Collectively, above results suggest that PCBP participates in neuronal MOR gene expression.
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Affiliation(s)
- Jane L Ko
- Department of Biology, Seton Hall University, South Orange, New Jersey 07079, USA.
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Hwang CK, Kim CS, Choi HS, McKercher SR, Loh HH. Transcriptional Regulation of Mouse μ Opioid Receptor Gene by PU.1. J Biol Chem 2004; 279:19764-74. [PMID: 14998994 DOI: 10.1074/jbc.m400755200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously reported that the 34-bp cis-acting element of the mouse micro opioid receptor (MOR) gene represses transcription of the MOR gene from the distal promoter. Using a yeast one-hybrid screen to identify potential transcription factors of the MOR promoter, we have identified PU.1 as one of the candidate genes. PU.1 is a member of the ets family of transcription factors, expressed predominantly in hematopoietic cells and microglia of brain. PU.1 plays an essential role in the development of both lymphoid and myeloid lineages. Opioids exert neuromodulatory as well as immunomodulatory effects, which are transduced by MOR. Moreover, MOR-deficient mice exhibit increased proliferation of hematopoietic cells, suggesting a possible link between the opioid system and hematopoietic development. The PU.1 protein binds to the 34-bp element of the MOR gene in a sequence-specific manner confirmed by electrophoretic mobility shift assay and supershift assays. We have also determined endogenous PU.1 interactions with the 34-bp element of MOR promoter by chromatin immunoprecipitation assays. In co-transfection studies PU.1 represses MOR promoter reporter constructs through its PU.1 binding site. When the PU.1 gene is disrupted as in PU.1 knock-out mice and using small interfering RNA-based strategy in RAW264.7 cells, the transcription of the endogenous target MOR gene is increased significantly. This increase is probably mediated through modification of the chromatin structure, as suggested by the reversal of the PU.1-mediated repression of MOR promoter activity after trichostatin A treatment in neuroblastoma NMB cells. Our results suggest that PU.1 may be an important regulator of the MOR gene, particularly in brain and immune cells.
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MESH Headings
- Amino Acid Motifs
- Animals
- Base Sequence
- Binding Sites
- Brain/metabolism
- Cell Division
- Cell Line
- Cell Line, Tumor
- Chromatin/metabolism
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Genes, Reporter
- Histone Deacetylases/metabolism
- Hydroxamic Acids/pharmacology
- Mice
- Mice, Knockout
- Molecular Sequence Data
- Plasmids/metabolism
- Precipitin Tests
- Promoter Regions, Genetic
- Protein Binding
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins/physiology
- Proto-Oncogene Proteins c-ets
- RNA, Small Interfering/metabolism
- Rats
- Receptors, Opioid, mu/biosynthesis
- Receptors, Opioid, mu/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Trans-Activators/metabolism
- Trans-Activators/physiology
- Transcription Factors/metabolism
- Transcription, Genetic
- Transfection
- Two-Hybrid System Techniques
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Affiliation(s)
- Cheol Kyu Hwang
- Department of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455, USA.
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13
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Ko JL, Liu HC, Loh HH. Role of an AP-2-like element in transcriptional regulation of mouse mu-opioid receptor gene. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 112:153-62. [PMID: 12670713 DOI: 10.1016/s0169-328x(03)00086-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Previously, several important cis-elements and trans-factors have been shown to play a functional role in the proximal promoter of mouse mu-opioid receptor (MOR) gene. In this study, we defined another functional element located the in -450 to -400 bp (translational start site designated as +1) region of the proximal promoter, which is also essential for the full promoter activity. It is designated as the morAP-2-like element for its sequence homologous to the consensus AP-2 element. Surprisingly, electrophoretic mobility shift analysis (EMSA) revealed that Sp1 and Sp3, but not AP-2 proteins, were specifically bound to the morAP-2-like element. Mutation of the morAP-2-like element, resulting in a loss of Sp binding, led to an approximately 35% decrease in activity, further confirming the positive role of the morAP-2-like element in MOR gene expression. Dephosphorylation of Sp proteins with alkaline phosphatase also decreased Sp binding to the morAP-2-like element in EMSA, suggesting phosphorylation of Sp is essential for its binding to this element. However, direct or indirect activation of PKA, a classical G-protein coupled signaling pathway, resulted in no significant change of Sp binding to the morAP-2-like element, nor of the promoter activity the SH-SY5Y cells, MOR expressing cells, suggesting that phosphorylation of Sp does not involve PKA. These results suggest that the binding of different phosphorylated forms of Sp proteins to the morAP-2-like element may contribute to the fine tuning of MOR expression in different cells.
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Affiliation(s)
- Jane L Ko
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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Hwang CK, Wu X, Wang G, Kim CS, Loh HH. Mouse mu opioid receptor distal promoter transcriptional regulation by SOX proteins. J Biol Chem 2003; 278:3742-50. [PMID: 12446692 DOI: 10.1074/jbc.m208780200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified transcription factors that bind to specific sequences in 5'-distal promoter regulatory sequences of the mouse mu opioid receptor (mor) promoter using the yeast one-hybrid system. The sequence between -746 and -707 in mor distal promoter was used as the bait because it acts as a functional promoter element and binds several DNA-binding proteins. From an adult mouse brain cDNA library, five cDNA clones encoding three Sox gene family (Sry like high mobility group (HMG) box gene) transcriptional factors, mSOX18, mSOX21, and mSOX6, were isolated. Electrophoretic mobility shift assays confirmed the presence of a binding site for SOX proteins in the -731/-725 region. Additionally, we have also established that the flanking regions outside the core Sox-binding site play an essential role in high affinity binding. DNase I footprint analysis indicates that proteins from mouse brain interact with the Sox-binding site within the mor distal promoter. Finally, we demonstrated that overexpression of mSOX18 and/or mSOX21 was able to up-regulate mouse mor distal promoter activity in mor-expressing neuronal cells (NMB). These data indicate that SOX proteins might contribute to the transcriptional activity of the mor gene and suggest that mu opioid receptor could mediate some of the developmental processes in which SOX proteins are included.
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Affiliation(s)
- Cheol Kyu Hwang
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis 55455, USA.
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15
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Xin L, Wang ZJ. Bioinformatic analysis of the human mu opioid receptor (OPRM1) splice and polymorphic variants. AAPS PHARMSCI 2002; 4:E23. [PMID: 12645995 PMCID: PMC2751312 DOI: 10.1208/ps040423] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mu opioid receptor (OPRM1), a member of the G-protein coupled receptor superfamily, mediates the analgesic and euphoric effects of opioid drugs. The sequences of OPRM1 cDNA and reported splice variants were used to search the public and Celera genomic databases. The matched sequences were analyzed to assemble an OPRM1 genomic contig. Human OPRM1 gene was estimated to span at least 90 kb in the chromosome 6q24-25 region. Four coding exons are separated by 3 introns. While intron 2 has only 773 bp, these databases for the first time provide the precise length of and other information about long introns 1 and 3, containing 50 and 27 kb, respectively. When a consensus exon/intron splice junction at the end of the coding exon 3 was not utilized, it may have resulted in continuous translation of the exon to yield the splice variant OPRM1A. The study did not identify human orthologs of other OPRM1 variants that had been reported for mouse OPRM1, although several proposed exons were found to be included in mouse genomic clones. Single nucleotide polymorphisms in the OPRM1 gene were also analyzed and summarized, which could provide potential polymorphic markers for molecular genetic studies.
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Affiliation(s)
- Lili Xin
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois, 60612 Chicago, IL
| | - Zaijie Jim Wang
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois, 60612 Chicago, IL
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16
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Ko JL, Chen HC, Loh HH. Differential promoter usage of mouse mu-opioid receptor gene during development. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 104:184-93. [PMID: 12225873 DOI: 10.1016/s0169-328x(02)00357-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Previously, we demonstrated that mouse mu-opioid receptor (MOR) gene expression is regulated by both distal and proximal promoters, with the latter playing a major role in controlling MOR transcription in the adult mouse brain. Here, we report studies of the relative usages of the mouse MOR dual promoters during murine development. We used the reverse transcription-polymerase chain reaction (RT-PCR) method, which gave results similar to those using binding assays or in situ hybridization. However, due to the greater sensitivity of RT-PCR method, we were able to detect the emergence of MOR as early as at embryonic day 8.5 (E8.5). We found that both proximal and distal promoters were active at E8.5. The proximal promoter initiated approximately two-thirds of total MOR transcripts at E8.5, with the distal promoter directing transcription of the remaining one-third. This is the greatest relative contribution of the distal promoter to MOR transcription we have observed during any time in development. Thereafter, the percentage of transcripts directed by the distal promoter gradually declined, and remained at a low but detectable level (approximately 5% of total MOR transcripts) throughout development and adulthood. Conversely, a progressive increase of the contribution of the proximal promoter to MOR transcription was observed during development, reaching its maximum in the adult. In summary, our results demonstrated the pivotal role of the proximal promoter in directing MOR transcription during murine development.
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Affiliation(s)
- Jane L Ko
- Department of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church Street S.E., Minneapolis, MN 55455, USA
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17
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Ko JL, Loh HH. Single-stranded DNA-binding complex involved in transcriptional regulation of mouse mu-opioid receptor gene. J Biol Chem 2001; 276:788-95. [PMID: 11027679 DOI: 10.1074/jbc.m004279200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we reported the presence of dual (distal and proximal) promoters in mouse mu-opioid receptor (mor) gene, with mor transcription in mouse brain predominantly initiated by the proximal promoter. Sp factors, bound to double-stranded (ds) cis-regulatory elements, are critical for proximal promoter activity. Here, we further report that a single-stranded (ss) cis-regulatory element and trans-acting protein factor are also important for proximal promoter activity. A 26-bp mor polypyrimidine/polypurine region (PPy/u) can adopt ss DNA conformation, as demonstrated by S1 nuclease sensitivity. Using electrophoretic mobility shift analysis with nuclear extracts from mor-expressing SH-SY5Y cells, we demonstrate that the sense strand of PPy/u interacts with a major nuclear protein, termed mor polypyrimidine-binding protein (mPy), which is not related to Sp factors. Southwestern blot analysis indicated that mPy protein is approximately 25 kDa in size. Functional analysis suggests that mPy protein can trans-activate mor promoter as well as a heterologous promoter. Moreover, combinatorial activation of ss (mPy) and ds (Sps) DNA binding factors, interacting with an overlapping DNA (PPy/u) region, is necessary for proximal promoter activation. Thus our results suggest that transcription of mouse mor gene is regulated by an interplay of ss and ds DNA binding factors.
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Affiliation(s)
- J L Ko
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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18
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Uhl GR, Sora I, Wang Z. The mu opiate receptor as a candidate gene for pain: polymorphisms, variations in expression, nociception, and opiate responses. Proc Natl Acad Sci U S A 1999; 96:7752-5. [PMID: 10393893 PMCID: PMC33614 DOI: 10.1073/pnas.96.14.7752] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There are differences between human individuals and between mouse strains in levels of mu opiate receptor (muOR) expression, responses to painful stimuli, and responses to opiate drugs. One of the best candidates for contributing to these differences is variation at the muOR gene locus. Support for this idea comes from analyses of the human and murine muOR genes. Assessments of individual differences in human muOR expression add further support. Studies with mice, including knockout-transgenic, quantitative trait locus, and strain-comparison studies, also strongly support the possibility that muOR gene alleles would be strong candidates for contributing to individual differences in human nociception and opiate drug responses. This paper reviews current analyses of the murine and human muOR genes, their important variants, and correlations between these variants and opiate influences on pain.
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Affiliation(s)
- G R Uhl
- Molecular Neurobiology Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
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19
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Andria ML, Simon EJ. Localization of promoter elements in the human mu-opioid receptor gene and regulation by DNA methylation. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 70:54-65. [PMID: 10381543 DOI: 10.1016/s0169-328x(99)00126-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The regulation of mu-opioid receptor gene expression was investigated using several molecular techniques. Genomic clones containing portions of the human mu-opioid receptor gene were sequenced. 5'-RACE analysis of human brain cDNA confirmed the presence of mRNAs up to -313 from the start codon. As was found for the mouse and rat genes, transcription apparently initiates in the absence of a discernable TATA box. To characterize promoter function, portions of the 5'-flanking region were linked to a reporter gene in transient transfection experiments. Two approximately 50 bp adjacent segments had potent, orientation specific promoter activity. More down-stream segments also had promoter activity. None of the 5'-flanking region constructs showed tissue specificity. The potential role of DNA methylation in preventing ectopic expression was investigated by surveying the methylation state of a CpG rich region straddling the start codon. A neural derived cell line (SH-SY5Y) that expresses the mu-opioid receptor lacked virtually any CpG methylation. In contrast, two neural derived cell lines that do not express the mu-opioid receptor were nearly totally methylated while non-neural cell lines had intermediate levels of CpG methylation. Additional transient transfection experiments revealed that CpG methylation of the 5'-flanking region suppressed reporter gene expression. These results indicate that CpG methylation plays an important role in regulating mu-opioid receptor expression in neural cells; however, no association was found with regulation of expression in non-neural cells.
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MESH Headings
- Animals
- Carcinoma, Squamous Cell/pathology
- CpG Islands
- DNA Methylation
- DNA, Complementary/genetics
- Gene Expression Regulation
- Genes, Reporter
- Humans
- Kidney
- L Cells
- Luciferases/biosynthesis
- Luciferases/genetics
- Mice
- Nerve Tissue Proteins/biosynthesis
- Nerve Tissue Proteins/genetics
- Neuroblastoma/pathology
- Organ Specificity
- Polymerase Chain Reaction
- Promoter Regions, Genetic
- Rats
- Receptors, Opioid, mu/biosynthesis
- Receptors, Opioid, mu/genetics
- Recombinant Fusion Proteins/biosynthesis
- Transcription, Genetic
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- M L Andria
- Department of Psychiatry, New York University Medical Center, Millhauser Labs HN605, New York, NY 10016, USA.
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Choe CY, Im HJ, Ko JL, Loh HH. Mouse mu opioid receptor gene expression. A 34-base pair cis-acting element inhibits transcription of the mu opioid receptor gene from the distal promoter. J Biol Chem 1998; 273:34926-32. [PMID: 9857022 PMCID: PMC3001105 DOI: 10.1074/jbc.273.52.34926] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 5'-flanking region of the mouse mu opioid receptor (MOR) gene has two promoters, referred to as distal and proximal, and the activities of each in the brain are quite different from each other. The 5'-distal promoter regulatory sequences (5'-DPRS), positioned between these two promoters, have strong inhibitory effects on the reporter gene expression driven by the MOR distal promoter. In our studies, detailed 3' deletion mapping of the 5'-DPRS narrowed down the negative cis-acting element to a 34-base pair (bp) segment (position -721 to -687). This 34-bp cis-acting element functions in both neuronal (NMB) and non-neuronal (CHO and RAW264.7) cultured cells. S1 nuclease protection assays indicated that this 34-bp cis-acting element suppresses distal promoter activity at the transcriptional level. Linker scanning mutagenesis demonstrated that nucleotides around position -721 and -689 in the 34-bp cis-acting element are essential for the regulation of distal promoter activity. Operational characterization of the 34-bp cis-acting element in the homologous MOR distal promoter and the heterologous SV40 promoter showed that its effects are position- and promoter-dependent while being orientation-independent in both promoters. Collectively, these data suggested that this 34-bp segment is a conditional transcriptional cis-acting element that blocks mouse MOR gene expression from the distal promoter.
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Affiliation(s)
- C y Choe
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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