Multiple and Slave Oscillators

Staiger, Dorothee; Streitner, Corinna; Rudolf, Fabian; Huang, Xi

doi:10.1002/9780470988527.ch3

Cited by 4 publications

(6 citation statements)

References 118 publications

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“…One third of the differentially expressed genes are controlled by the circadian clock, in line with the proposed function of the At GRP7 feedback loop as a slave oscillator in clock output [40,41]. Binding of the morning-phased LHY and CCA1 clock proteins to the promoters of some morning-specific genes shows that rhythmic transcripts can be directly controlled by the core oscillator proteins [14].…”

Section: Discussionmentioning

confidence: 88%

Global transcript profiling of transgenic plants constitutively overexpressing the RNA-binding protein AtGRP7

et al. 2010

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BackgroundThe clock-controlled RNA-binding protein AtGRP7 influences circadian oscillations of its own transcript at the post-transcriptional level. To identify additional targets that are regulated by AtGRP7, transcript profiles of transgenic plants constitutively overexpressing AtGRP7 (AtGRP7-ox) and wild type plants were compared.ResultsApproximately 1.4% of the transcripts represented on the Affymetrix ATH1 microarray showed changes in steady-state abundance upon AtGRP7 overexpression. One third of the differentially expressed genes are controlled by the circadian clock, and they show a distinct bias of their phase: The up-regulated genes preferentially peak around dawn, roughly opposite to the AtGRP7 peak abundance whereas the down-regulated genes preferentially peak at the end of the day. Further, transcripts responsive to abiotic and biotic stimuli were enriched among AtGRP7 targets. Transcripts encoding the pathogenesis-related PR1 and PR2 proteins were elevated in AtGRP7-ox plants but not in plants overexpressing AtGRP7 with a point mutation in the RNA-binding domain, indicating that the regulation involves RNA binding activity of AtGRP7. Gene set enrichment analysis uncovered components involved in ribosome function and RNA metabolism among groups of genes upregulated in AtGRP7-ox plants, consistent with its role in post-transcriptional regulation.ConclusionApart from regulating a suite of circadian transcripts in a time-of-day dependent manner AtGRP7, both directly and indirectly, affects other transcripts including transcripts responsive to abiotic and biotic stimuli. This suggests a regulatory role of AtGRP7 in the output of the endogenous clock and a complex network of transcripts responsive to external stimuli downstream of the AtGRP7 autoregulatory circuit.

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Section: Discussionmentioning

confidence: 88%

Global transcript profiling of transgenic plants constitutively overexpressing the RNA-binding protein AtGRP7

et al. 2010

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“…Accumulating evidence points to the importance of post-transcriptional control, a layer between transcription and translation, in the circadian system ( Fig. 1a) [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Spotlight on post-transcriptional control in the circadian system

Staiger

Köster

2010

Cell. Mol. Life Sci.

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An endogenous timing mechanism, the circadian clock, causes rhythmic expression of a considerable fraction of the genome of most organisms to optimally align physiology and behavior with their environment. Circadian clocks are self-sustained oscillators primarily based on transcriptional feedback loops and post-translational modification of clock proteins. It is increasingly becoming clear that regulation at the RNA level strongly impacts the cellular circadian transcriptome and proteome as well as the oscillator mechanism itself. This review focuses on posttranscriptional events, discussing RNA-binding proteins that, by influencing the timing of pre-mRNA splicing, polyadenylation and RNA decay, shape rhythmic expression profiles. Furthermore, recent findings on the contribution of microRNAs to orchestrating circadian rhythms are summarized.

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“…Apart from regulating their own expression, clock proteins transduce rhythmicity to produce overt rhythms. They may accomplish this by direct control of downstream genes or via cascades of oscillating gene products (Brown and Schibler, 1999; Staiger et al. , 2006).…”

Section: Introductionmentioning

confidence: 99%

Auto‐regulation of the circadian slave oscillator component AtGRP7 and regulation of its targets is impaired by a single RNA recognition motif point mutation

et al. 2007

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SummaryThe clock-regulated RNA-binding protein AtGRP7 (Arabidopsis thaliana glycine-rich RNA-binding protein) influences circadian oscillations of its transcript by negative feedback at the post-transcriptional level. Here we show that site-specific mutation of one conserved arginine to glutamine within the RNA recognition motif impairs binding of recombinant AtGRP7 to its pre-mRNA in vitro. This correlates with the loss of the negative auto-regulation in vivo: in transgenic plants constitutively overexpressing AtGRP7 (AtGRP7-ox), a shift occurs to an alternatively spliced AtGRP7 transcript that decays rapidly, and thus does not accumulate to high levels. In contrast, constitutive ectopic overexpression of the AtGRP7-RQ mutant does not lead to alternative splicing of the endogenous AtGRP7 transcript and concomitant damping of the oscillations. This highlights the importance of AtGRP7 binding to its own transcript for the negative auto-regulatory circuit. Moreover, regulation of AtGRP7 downstream targets also depends on its RNA-binding activity, as AtGRP8 and other targets identified by transcript profiling of wild-type and AtGRP7-ox plants using fluorescent differential display are negatively affected by AtGRP7 but not by AtGRP7-RQ. In mutants impaired in the nonsensemediated decay (NMD) components UPF1 or UPF3, levels of the alternatively spliced AtGRP7 and AtGRP8 transcripts that contain premature termination codons are strongly elevated, implicating UPF1 and UPF3 in the decay of these clock-regulated transcripts.

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Multiple and Slave Oscillators

Cited by 4 publications

References 118 publications

Global transcript profiling of transgenic plants constitutively overexpressing the RNA-binding protein AtGRP7

Global transcript profiling of transgenic plants constitutively overexpressing the RNA-binding protein AtGRP7

Spotlight on post-transcriptional control in the circadian system

Auto‐regulation of the circadian slave oscillator component AtGRP7 and regulation of its targets is impaired by a single RNA recognition motif point mutation

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