Noise Can Induce Bimodality in Positive Transcriptional Feedback Loops Without Bistability

Science ◽  
2010 ◽  
Vol 327 (5969) ◽  
pp. 1142-1145 ◽  
Author(s):  
T.-L. To ◽  
N. Maheshri
Keyword(s):  
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 Interlocking Transcriptional Feedback Loops Control White-Opaque Switching in Candida albicans

PLoS Biology ◽  
2007 ◽  
Vol 5 (10) ◽  
pp. e256 ◽  
Author(s):  
Rebecca E Zordan ◽  
Mathew G Miller ◽  
David J Galgoczy ◽  
Brian B Tuch ◽  
Alexander D Johnson
Keyword(s):  
Candida Albicans ◽  
Feedback Loops ◽  
Transcriptional Feedback

scholarly journals Accurate timekeeping is controlled by a cycling activator in Arabidopsis

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Polly Yingshan Hsu ◽  
Upendra K Devisetty ◽  
Stacey L Harmer
Keyword(s):  
Regulatory Network ◽  
Clock Gene ◽  
Regulatory Mechanism ◽  
Clock Genes ◽  
Feedback Loops ◽  
Transcriptional Repressors ◽  
Gene Transcripts ◽  
And Control ◽  
Complex Regulatory Network ◽  
Transcriptional Feedback

Transcriptional feedback loops are key to circadian clock function in many organisms. Current models of the Arabidopsis circadian network consist of several coupled feedback loops composed almost exclusively of transcriptional repressors. Indeed, a central regulatory mechanism is the repression of evening-phased clock genes via the binding of morning-phased Myb-like repressors to evening element (EE) promoter motifs. We now demonstrate that a related Myb-like protein, REVEILLE8 (RVE8), is a direct transcriptional activator of EE-containing clock and output genes. Loss of RVE8 and its close homologs causes a delay and reduction in levels of evening-phased clock gene transcripts and significant lengthening of clock pace. Our data suggest a substantially revised model of the circadian oscillator, with a clock-regulated activator essential both for clock progression and control of clock outputs. Further, our work suggests that the plant clock consists of a highly interconnected, complex regulatory network rather than of coupled morning and evening feedback loops.

scholarly journals An RNAi Screen To Identify Protein Phosphatases That Function Within the Drosophila Circadian Clock

2016 ◽  
Vol 6 (12) ◽  
pp. 4227-4238 ◽  
Author(s):  
Parul Agrawal ◽  
Paul E Hardin
Keyword(s):  
Protein Phosphatase ◽  
Feedback Loop ◽  
Protein Phosphatases ◽  
Clock Cycle ◽  
Feedback Loops ◽  
Model Systems ◽  
Circadian Period ◽  
Loss Of Function ◽  
Future Studies ◽  
Transcriptional Feedback

Abstract Circadian clocks in eukaryotes keep time via cell-autonomous transcriptional feedback loops. A well-characterized example of such a transcriptional feedback loop is in Drosophila, where CLOCK-CYCLE (CLK-CYC) complexes activate transcription of period (per) and timeless (tim) genes, rising levels of PER-TIM complexes feed-back to repress CLK-CYC activity, and degradation of PER and TIM permits the next cycle of CLK-CYC transcription. The timing of CLK-CYC activation and PER-TIM repression is regulated posttranslationally, in part through rhythmic phosphorylation of CLK, PER, and TIM. Previous behavioral screens identified several kinases that control CLK, PER, and TIM levels, subcellular localization, and/or activity, but two phosphatases that function within the clock were identified through the analysis of candidate genes from other pathways or model systems. To identify phosphatases that play a role in the clock, we screened clock cell-specific RNA interference (RNAi) knockdowns of all annotated protein phosphatases and protein phosphatase regulators in Drosophila for altered activity rhythms. This screen identified 19 protein phosphatases that lengthened or shortened the circadian period by ≥1 hr (p ≤ 0.05 compared to controls) or were arrhythmic. Additional RNAi lines, transposon inserts, overexpression, and loss-of-function mutants were tested to independently confirm these RNAi phenotypes. Based on genetic validation and molecular analysis, 15 viable protein phosphatases remain for future studies. These candidates are expected to reveal novel features of the circadian timekeeping mechanism in Drosophila that are likely to be conserved in all animals including humans.

scholarly journals Loss of Synergistic Transcriptional Feedback Loops Drives Diverse B-Cell Cancers

2021 ◽  
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
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