Functional independence of circadian clocks that regulate plant gene expression

Thain, Simon C.; Hall, Anthony; Millar, Andrew J.

doi:10.1016/s0960-9822(00)00630-8

Cited by 157 publications

(149 citation statements)

References 35 publications

Supporting

Mentioning

132

Contrasting

Unclassified

Order By: Relevance

“…This implies the presence of the photoreceptors and signal transduction system of the light input pathway, of all of the essential elements of the central oscillator, and of at least those components of the output pathway that regulate gene expression. Our results support a previous report of cell autonomous circadian activity in LL in intact plants (25), and extend this finding to cell culture in LL and DD (Fig. 2D).…”

Section: Discussionsupporting

confidence: 93%

Circadian phase-specific degradation of the F-box protein ZTL is mediated by the proteasome

Kim¹,

Geng²,

Somers³

2003

Proc. Natl. Acad. Sci. U.S.A.

130

116

View full text Add to dashboard Cite

Critical to the maintenance of circadian rhythmicity is the cyclic expression of at least some components of the central oscillator. High-amplitude cycling of mRNA and protein abundance, protein phosphorylation and nuclear͞cytoplasmic shuttling have all been implicated in the maintenance of circadian period. Here we use a newly characterized Arabidopsis suspension cell culture to establish that the rhythmic changes in the levels of the clock-associated F-box protein, ZTL, are posttranscriptionally controlled through different circadian phase-specific degradation rates. This proteolysis is proteasome dependent, implicating ZTL itself as substrate for ubiquitination. This demonstration of circadian phase-regulated degradation of an F-box protein, which itself controls circadian period, suggests a novel regulatory feedback mechanism among known circadian systems.

show abstract

Section: Discussionsupporting

confidence: 93%

Circadian phase-specific degradation of the F-box protein ZTL is mediated by the proteasome

Kim¹,

Geng²,

Somers³

2003

Proc. Natl. Acad. Sci. U.S.A.

130

116

View full text Add to dashboard Cite

show abstract

“…By combining tissue-specific bioluminescence and transcriptional assays, we were able to show that PRR3 plays an important role in the progression of the circadian clock in the vasculature, as decreased levels of PRR3 caused an evident shortening of the period of the clock-controlled genes that are expressed mainly in the same tissue. Together with previous observations (Thain et al, 2000(Thain et al, , 2002, our findings suggest the existence of a tissue-specific circadian clock mechanism. Moreover, one of the most important clock output pathways for time measurement in photoperiodic responses has been shown to act through tissue-specific factors Kay, 2006).…”

Section: Prr3 Plays a Role In Clock Progression In The Vasculaturesupporting

confidence: 88%

PRR3 Is a Vascular Regulator of TOC1 Stability in theArabidopsisCircadian Clock

et al. 2007

View full text Add to dashboard Cite

The pseudoresponse regulators (PRRs) participate in the progression of the circadian clock in Arabidopsis thaliana. The founding member of the family, TIMING OF CAB EXPRESSION1 (TOC1), is an essential component of the transcriptional network that constitutes the core mechanism of the circadian oscillator. Recent data suggest a role in circadian regulation for all five members of the PRR family; however, the molecular function of TOC1 or any other PRRs remains unknown. In this work, we present evidence for the involvement of PRR3 in the regulation of TOC1 protein stability. PRR3 was temporally coexpressed with TOC1 under different photoperiods, yet its tissue expression was only partially overlapping with that of TOC1, as PRR3 appeared restricted to the vasculature. Decreased expression of PRR3 resulted in reduced levels of TOC1 protein, while overexpression of PRR3 caused an increase in the levels of TOC1, all without affecting the amount of TOC1 transcript. PRR3 was able to bind to TOC1 in yeast and in plants and to perturb TOC1 interaction with ZEITLUPE (ZTL), which targets TOC1 for proteasome-dependent degradation. Together, our results indicate that PRR3 might function to modulate TOC1 stability by hindering ZTL-dependent TOC1 degradation, suggesting the existence of local regulators of clock activity and adding to the growing importance of posttranslational regulation in the design of circadian timing mechanisms in plants.

show abstract

“…Luminescence levels were quantified on either a low-light imaging system or an adapted microtiter plate-reading scintillation counter and analyzed essentially as described (McWatters et al, 2000;Thain et al, 2000), using the software package MetaMorph (Universal Imaging Corp.), and the macro suites I&A, TopTempII, and Biological Rhythms Analysis Software System ; available at http://www.amillar.org) and fast Fourier transform-nonlinear least squares (Plautz et al, 1997). Sustainability (precision) of rhythms was derived from measurements of the relative amplitude of error (RAE) as a method that has previously been reported (Allen et al, 2006;Izumo et al, 2006).…”

Section: Rhythm Data Analysismentioning

confidence: 99%

ELF4Is Required for Oscillatory Properties of the Circadian Clock

et al. 2007

Self Cite

View full text Add to dashboard Cite

Circadian clocks are required to coordinate metabolism and physiology with daily changes in the environment. Such clocks have several distinctive features, including a free-running rhythm of approximately 24 h and the ability to entrain to both light or temperature cycles (zeitgebers). We have previously characterized the EARLY FLOWERING4 (ELF4) locus of Arabidopsis (Arabidopsis thaliana) as being important for robust rhythms. Here, it is shown that ELF4 is necessary for at least two core clock functions: entrainment to an environmental cycle and rhythm sustainability under constant conditions. We show that elf4 demonstrates clock input defects in light responsiveness and in circadian gating. Rhythmicity in elf4 could be driven by an environmental cycle, but an increased sensitivity to light means the circadian system of elf4 plants does not entrain normally. Expression of putative core clock genes and outputs were characterized in various ELF4 backgrounds to establish the molecular network of action. ELF4 was found to be intimately associated with the CIRCADIAN CLOCK-ASSOCIATED1 (CCA1)/LONG ELONGATED HYPOCOTYL (LHY)-TIMING OF CAB EXPRESSION1 (TOC1) feedback loop because, under free run, ELF4 is required to regulate the expression of CCA1 and TOC1 and, further, elf4 is locked in the evening phase of this feedback loop. ELF4, therefore, can be considered a component of the central CCA1/LHY-TOC1 feedback loop in the plant circadian clock.

show abstract

Functional independence of circadian clocks that regulate plant gene expression

Abstract: Higher plants contain a spatial array of autonomous circadian clocks that regulate gene expression without a localised pacemaker. Circadian timing in plants might be less accurate but more flexible than the vertebrate circadian system.

Cited by 157 publications

References 35 publications

Circadian phase-specific degradation of the F-box protein ZTL is mediated by the proteasome

Circadian phase-specific degradation of the F-box protein ZTL is mediated by the proteasome

PRR3 Is a Vascular Regulator of TOC1 Stability in theArabidopsisCircadian Clock

ELF4Is Required for Oscillatory Properties of the Circadian Clock

Contact Info

Product

Resources

About