title: Retinoic acid regulation of mu opioid receptor and c-fos mRNAs and AP-1 DNA binding in SH-SY5Y neuroblastoma cells.
abstract: Retinoic acid (RA) induced differentiation of SH-SY5Y cells increases the expression of mu opioid receptors (HMOR) and inhibitory G proteins, as well as the efficacy of opioids to inhibit forskolin-induced adenylyl cyclase activity. We examined the time course of the effects of all-trans retinoic acid (RA) on HMOR and c-fos mRNA levels as determined by solution hybridization (using HMOR and rat c-fos riboprobes) in RNA extracts from SH-SY5Y cells. Electrophoretic Mobility Shift Assay (EMSA) and Western blot analysis were used to assess the changes AP-1 DNA binding and the presence of fos-related proteins in nuclear extracts from untreated, vehicle (ethanol) or RA-treated SH-SY5Y cells. Exposure to RA for 0.5 h had no effect on HMOR while after 6-18 h of exposure HMOR in mRNA levels were decreased by 50% and then after 168 h of RA exposure, HMOR mRNA levels were doubled. In contrast, c-fos mRNA levels were unchanged at 0.5 h, but increased by 50% after 18 and 168 h of RA exposure. RA increased AP-1 binding after 18 and 168 h and a pan fos-FRA antibody produced a supershift. Western analysis indicates that RA activates a 45-kDa protein corresponding to the size of the fos B protein. These results identify two signal transduction targets that are regulated by RA during differentiation.
authors.affiliation: Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: Shirzad
authors.initials: S
authors.lastname: Jenab
authors.forename: Charles E
authors.initials: CE
authors.lastname: Inturrisi
mesh_terms: D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000378:metabolism* / Q000503:physiopathology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000235:genetics*; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D017450:Receptors, Opioid, mu; D018808:Transcription Factor AP-1; D014212:Tretinoin; D004247:DNA