Functional characterization of the promoter region of the human mu opioid receptor (hMOR) gene: identification of activating and inhibitory regions.
The mu opioid receptor (MOR) is thought to mediate a variety of morphine's effects, including analgesia and addiction. The expression of opioid receptors can be up and down regulated, but little is known about molecular processes that regulate expression of the MOR gene. To study the regulatory elements that control expression of the human MOR (hMOR) gene, 2325 bp of the 5'-regulatory sequence of the hMOR gene were cloned and sequenced. A transcription initiation site (TIS) was mapped 252 (-252) nucleotides upstream from the translation start site (+1) by primer extension experiments using human thalamus poly(A)+ mRNA. In addition, several putative distal TISs were also identified; the most distal site was mapped 663 bp upstream of the translation start site. A series of 5'-deleted hMOR promoter-luciferase constructs were made and transiently transfected into a MOR expressing neuroblastoma cell line, SK-N-SH, and a non-expressing cell line, HeLa. These transient transfection studies indicated that the region from -563 to -292 contained a strong enhancer element(s), while the region from -776 to -564 possessed a repressor element(s). A similar transfection pattern was observed with SK-N-SH and HeLa cells, suggesting that there is not a tissue-specific element in the region from -2325 to -252.
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Department of Medicine, Indiana University School of Medicine, Indianapolis 46202-5121, USA.
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D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005809:Genes, Regulator; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D017450:Receptors, Opioid, mu / Q000235:genetics*; D017384:Sequence Deletion; D014158:Transcription, Genetic; D014162:Transfection
D017450:Receptors, Opioid, mu; D004247:DNA; D008156:Luciferases