scholarly journals Wheels within wheels: new transcriptional feedback loops in the Arabidopsis circadian clock

10.12703/p6-2 ◽  
2014 ◽  
Vol 6 ◽  
Author(s):  
C. Robertson McClung
Keyword(s):  
Circadian Clock ◽  
Feedback Loops ◽  
Transcriptional Feedback

scholarly journals Loss of synergistic transcriptional feedback loops drives diverse B-cell cancers

EBioMedicine ◽  
2021 ◽  
Vol 71 ◽  
pp. 103559
Author(s):  
Jared M. Andrews ◽  
Sarah C. Pyfrom ◽  
Jennifer A. Schmidt ◽  
Olivia I. Koues ◽  
Rodney A. Kowalewski ◽  
...  
Keyword(s):  
B Cell ◽  
Feedback Loops ◽  
Transcriptional Feedback

scholarly journals Deciphering the Dynamics of Interlocked Feedback Loops in a Model of the Mammalian Circadian Clock

2018 ◽  
Vol 115 (10) ◽  
pp. 2055-2066 ◽  
Author(s):  
Dorjsuren Battogtokh ◽  
John J. Tyson
Keyword(s):  
Circadian Clock ◽  
Feedback Loops

The Circadian Clock inArabidopsisRoots Is a Simplified Slave Version of the Clock in Shoots

Science ◽  
2008 ◽  
Vol 322 (5909) ◽  
pp. 1832-1835 ◽  
Author(s):  
Allan B. James ◽  
José A. Monreal ◽  
Gillian A. Nimmo ◽  
Ciarán L. Kelly ◽  
Pawel Herzyk ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Circadian Clock ◽  
Clock Genes ◽  
Plant Cells ◽  
Feedback Loops ◽  
Circadian Oscillator ◽  
Inhibit Gene Expression ◽  
Organ Specific ◽  
Plant Clock

The circadian oscillator in eukaryotes consists of several interlocking feedback loops through which the expression of clock genes is controlled. It is generally assumed that all plant cells contain essentially identical and cell-autonomous multiloop clocks. Here, we show that the circadian clock in the roots of matureArabidopsisplants differs markedly from that in the shoots and that the root clock is synchronized by a photosynthesis-related signal from the shoot. Two of the feedback loops of the plant circadian clock are disengaged in roots, because two key clock components, the transcription factors CCA1 and LHY, are able to inhibit gene expression in shoots but not in roots. Thus, the plant clock is organ-specific but not organ-autonomous.

scholarly journals MECHANISMS IN ENDOCRINOLOGY: A sense of time of the glucocorticoid circadian clock: from the ontogeny to the diagnosis of Cushing’s syndrome

2018 ◽  
Vol 179 (1) ◽  
pp. R1-R18 ◽  
Author(s):  
Ayrton Custodio Moreira ◽  
Sonir Rauber Antonini ◽  
Margaret de Castro
Keyword(s):  
Circadian Rhythm ◽  
Circadian Clock ◽  
Clock Genes ◽  
Circadian Variation ◽  
Circadian System ◽  
Feedback Loops ◽  
Adrenal Axis ◽  
Sense Of Time ◽  
Pituitary Adrenal Axis ◽  
Hierarchical Manner

The circadian rhythm of glucocorticoids has long been recognised within the last 75 years. Since the beginning, researchers have sought to identify basic mechanisms underlying the origin and emergence of the corticosteroid circadian rhythmicity among mammals. Accordingly, Young, Hall and Rosbash, laureates of the 2017 Nobel Prize in Physiology or Medicine, as well as Takahashi’s group among others, have characterised the molecular cogwheels of the circadian system, describing interlocking transcription/translation feedback loops essential for normal circadian rhythms. Plasma glucocorticoid circadian variation depends on the expression of intrinsic clock genes within the anatomic components of the hypothalamic–pituitary–adrenal axis, which are organised in a hierarchical manner. This review presents a general overview of the glucocorticoid circadian clock mechanisms, highlighting the ontogeny of the pituitary–adrenal axis diurnal rhythmicity as well as the involvement of circadian rhythm abnormalities in the physiopathology and diagnosis of Cushing’s disease.

scholarly journals CIRCADIAN CLOCK ASSOCIATED 1 and ATAF2 differentially suppress cytochrome P450-mediated brassinosteroid inactivation

2019 ◽  
Vol 71 (3) ◽  
pp. 970-985 ◽  
Author(s):  
Hao Peng ◽  
Michael M Neff
Keyword(s):  
Circadian Clock ◽  
Double Mutant ◽  
Expression Patterns ◽  
Regulatory Protein ◽  
Feedback Loops ◽  
Cytochrome P450s ◽  
Plant Tissues ◽  
Null Mutant ◽  
Plant Growth And Development ◽  
Protein Levels

Abstract Brassinosteroids (BRs) are a group of steroid hormones regulating plant growth and development. Since BRs do not undergo transport among plant tissues, their metabolism is tightly regulated by transcription factors (TFs) and feedback loops. BAS1 (CYP734A1, formerly CYP72B1) and SOB7 (CYP72C1) are two BR-inactivating cytochrome P450s identified in Arabidopsis thaliana. We previously found that a TF ATAF2 (ANAC081) suppresses BAS1 and SOB7 expression by binding to the Evening Element (EE) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1)-binding site (CBS) on their promoters. Both the EE and CBS are known binding targets of the circadian regulatory protein CCA1. Here, we confirm that CCA1 binds the EE and CBS motifs on BAS1 and SOB7 promoters, respectively. Elevated accumulations of BAS1 and SOB7 transcripts in the CCA1 null mutant cca1-1 indicate that CCA1 is a repressor of their expression. When compared with either cca1-1 or the ATAF2 null mutant ataf2-2, the cca1-1 ataf2-2 double mutant shows higher SOB7 transcript accumulations and a stronger BR-insensitive phenotype of hypocotyl elongation in white light. CCA1 interacts with ATAF2 at both DNA–protein and protein–protein levels. ATAF2, BAS1, and SOB7 are all circadian regulated with distinct expression patterns. These results demonstrate that CCA1 and ATAF2 differentially suppress BAS1- and SOB7-mediated BR inactivation.

PREMONition: An algorithm for predicting the circadian clock-regulated molecular network

2018 ◽  
Author(s):  
Jasper Bosman ◽  
Zheng Eelderink-Chen ◽  
Emma Laing ◽  
Martha Merrow
Keyword(s):  
Circadian Clock ◽  
Clock Gene ◽  
Clock Genes ◽  
Circadian Clocks ◽  
Model Systems ◽  
Functional Relationships ◽  
Growth Assay ◽  
Living Organisms ◽  
Clock Mechanism ◽  
Transcriptional Feedback

AbstractA transcriptional feedback loop is central to clock function in animals, plants and fungi. The clock genes involved in its regulation are specific to - and highly conserved within - the kingdoms of life. However, other shared clock mechanisms, such as phosphorylation, are mediated by proteins found broadly among living organisms, performing functions in many cellular sub-systems. Use of homology to directly infer involvement/association with the clock mechanism in new, developing model systems, is therefore of limited use. Here we describe the approach PREMONition,PREdictingMolecularNetworks, that uses functional relationships to predict molecular circadian clock associations. PREMONition is based on the incorporation of proteins encoded by known clock genes (when available), rhythmically expressed clock-controlled genes and non-rhythmically expressed but interacting genes into a cohesive network. After tuning PREMONition on the networks derived for human, fly and fungal circadian clocks, we deployed the approach to predict a molecular clock network forSaccharomyces cerevisiae, for which there are no readily-identifiable clock gene homologs. The predicted network was validated using gene expression data and a growth assay for sensitivity to light, a zeitgeber of circadian clocks of most organisms. PREMONition may be used to identify candidate clock-regulated processes and thus candidate clock genes in other organisms.

Overlapping and specialised functions of LHY and CCA1 in interacting feedback loops of the Arabidopsis circadian clock

2003 ◽  
Vol 2003 (Spring) ◽  
Author(s):  
Isabelle Carre ◽  
Bethan Taylor ◽  
Hae-Ryong Song ◽  
Jae-Yean Kim
Keyword(s):  
Circadian Clock ◽  
Feedback Loops

Interlocked feedback loops of the circadian clock of Neurospora crassa

2008 ◽  
Vol 68 (2) ◽  
pp. 255-262 ◽  
Author(s):  
Michael Brunner ◽  
Krisztina Káldi
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Feedback Loops
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