title: The harmala alkaloid harmine is a modulator of circadian Bmal1 transcription.
abstract: Biological rhythms are orchestrated by a cell-autonomous clock system that drives the rhythmic cascade of clock genes. We established an assay system using NIH 3T3 cells stably expressing the Bmal1 promoter-driven luciferase reporter gene and used it to analyse circadian oscillation of the gene. Modulators of PKC (protein kinase C) revealed that an activator and an inhibitor represented short- and long-period phenotypes respectively which were consistent with reported effects of PKC on the circadian clock and validated the assay system. We examined the effects of the alkaloid harmine, contained in Hoasca, which has a wide spectrum of pharmacological actions, on circadian rhythms using the validated assay system. Harmine dose dependently elongated the period. Furthermore, EMSA (electrophoretic mobility-shift assay) and Western-blot analysis showed that harmine enhanced the transactivating function of RORα (retinoid-related orphan receptor α), probably by increasing its nuclear translocation. Exogenous expression of RORα also caused a long period, confirming the phenotype indicated by harmine. These results suggest that harmine extends the circadian period by enhancing RORα function and that harmine is a new candidate that contributes to the control of period length in mammalian cells.
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba 305-8566, Japan. y-onishi@aist.go.jp
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Onishi
authors.forename: Katsutaka
authors.initials: K
authors.lastname: Oishi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kawano
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Yamazaki
mesh_terms: D056930:ARNTL Transcription Factors / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000187:drug effects*; D017930:Genes, Reporter; D006247:Harmine / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1 / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
chemical_list: D056930:ARNTL Transcription Factors; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; C539739:Rora protein, mouse; D006247:Harmine; D008156:Luciferases