title: Cell autonomous circadian waves of the APRR1/TOC1 quintet in an established cell line of Arabidopsis thaliana.
abstract: A small family of genes, named Arabidopsis Pseudo Response Regulator (APRR), are intriguing with special reference to circadian rhythms in plants, based on the fact that one of the members (APRR1) is identical to TOC1 (Timing of CAB Expression 1) that is believed to encode a clock component. In Arabidopsis plants, each transcript of the APRR1/TOC1 quintet genes starts accumulating after dawn rhythmically and one after another at intervals in the order of APRR9 --> APRR7 --> APRR5 --> APRR3 --> APRR1/TOC1. To characterize such intriguing circadian-associated events, we employed an established Arabidopsis cell line (named T87). When T87 cells were grown in an appropriate light and dark cycle, cell autonomous diurnal oscillations of the APRR1/TOC1 quintet genes were observed at the level of transcription, as seen in intact plants. After transfer to the conditions without any environmental time cues, particularly in constant dark, we further showed that free-running circadian rhythms persisted in the cultured cells, not only for the APRR1/TOC1 quintet genes, but also other typical circadian-controlled genes including CCA1 (Circadian Clock Associated 1), LHY (Late Elongated Hypocotyl) and CCR2 (Cold Circadian Rhythm RNA Binding 2). To our knowledge, this is the first indication of cell autonomous circadian rhythms in cultured cells in Arabidopsis thaliana, which will provide us with an alternative and advantageous means to characterize the plant biological clock.
authors.affiliation: Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya, 464-8601 Japan.
authors.forename: Norihito
authors.initials: N
authors.lastname: Nakamichi
authors.forename: Akinori
authors.initials: A
authors.lastname: Matsushika
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yamashino
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mizuno
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D015152:Blotting, Northern; D002460:Cell Line; D002940:Circadian Rhythm / Q000502:physiology*; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000235:genetics; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D005810:Multigene Family / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic / Q000528:radiation effects
chemical_list: C448162:APRR3 protein, Arabidopsis; C448160:APRR5 protein, Arabidopsis; C448161:APRR7 protein, Arabidopsis; C448159:APRR9 protein, Arabidopsis; D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; D016601:RNA-Binding Proteins; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors