title: Identification of three mouse mu-opioid receptor (MOR) gene (Oprm1) splice variants containing a newly identified alternatively spliced exon.
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.
authors.affiliation: The Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States. e_gad@verizon.net
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Doyle
authors.forename: X
authors.initials: X
authors.lastname: Rebecca Sheng
authors.forename: Sharon S J
authors.initials: SS
authors.lastname: Lin
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Press
authors.forename: Dorothy E
authors.initials: DE
authors.lastname: Grice
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Buono
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Ferraro
authors.forename: Wade H
authors.initials: WH
authors.lastname: Berrettini
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D005091:Exons / Q000235:genetics*; D015870:Gene Expression; D008297:Male; D051379:Mice / Q000235:genetics*; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; C404943:Oprm protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D017450:Receptors, Opioid, mu