Classical opioids have been historically used for the treatment of pain and are among the most widely used drugs for both acute severe pain and long-term pain. Morphine and endogenous mu-opioid peptides exert their pharmacological actions mainly through the mu-opioid receptor (MOR). However, the expression of opioid receptor (OR) proteins is controlled by extensive transcriptional and post-transcriptional processing. Previously, the 50-untranslated region (UTR) of the mouse MOR was found to be important for post-transcriptional regulation of the MOR gene in neuronal cells. To identify proteins binding to the 50-UTR as potential regulators of the mouse MOR gene, affinity column chromatography using 50-UTR-specific RNA oligonucleotides was performed using neuroblastoma NS20Y cells. Chromatography was followed by two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. We identified two heterogeneous ribonucleoproteins (hnRNPs) that bound to RNA sequences of interest: hnRNP H1 and hnRNP F. Binding of these proteins to the RNA region was M4-region sequence-specific as confirmed by Western-blot analysis and RNA supershift assay. Furthermore, a cotransfection study showed that the presence of hnRNP H1 and F resulted in repressed expression of the mouse MOR. Our data suggest that hnRNP H1 and F can function as repressors of MOR translation dependent on the M4 (-75 to -71 bp upstream of ATG) sequences. We demonstrate for the first time a role of hnRNPs as posttranscriptional repressors in MOR gene regulation.
|Original language||English (US)|
|Number of pages||12|
|Journal||Cellular and Molecular Life Sciences|
|State||Published - Feb 2012|
Bibliographical noteFunding Information:
This work was supported by the National Institutes of Health (Grants DA000564, DA001583, DA011806, K05-DA070554, DA011190, DA013926), and by the A&F Stark Fund of the Minnesota Medical Foundation.
- Mu-opioid receptor (MOR)
- Post-transcriptional regulation
- RNA binding protein