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Eukaryotic circadian systems: cycles in common
1Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA. jay.c.dunlap@dartmouth.edu
Abstract:
Common regulatory patterns can now be discerned among eukaryotic circadian systems, extending from fungi through to mammals. Complexes of two distinct PAS domain-containing transcription factors play positive roles in clock-associated feedback loops by turning on classic clock proteins such as FRQ, PER and TIM. These in turn appear to act as negative elements, interfering with their own activation and thus giving rise to an oscillatory negative feedback loop. Post-transcriptional control governs the amount and type of FRQ and makes the clock responsive to temperature.
Insights
Eukaryotic circadian systems share regulatory patterns. PAS domain transcription factors activate clock proteins, which then inhibit their own production, creating a feedback loop responsive to temperature.
Area of Science:
- * Molecular biology
- * Chronobiology
- * Genetics
Background:
- * Eukaryotic circadian systems exhibit conserved regulatory mechanisms across diverse species, from fungi to mammals.
- * Understanding these molecular underpinnings is crucial for deciphering biological timekeeping.
- * Previous research has identified key protein families involved in circadian rhythm regulation.
Purpose of the Study:
- * To elucidate the common regulatory patterns in eukaryotic circadian systems.
- * To identify the roles of specific transcription factor complexes in circadian feedback loops.
- * To investigate the influence of post-transcriptional control and temperature on circadian clock function.
Main Methods:
- * Comparative analysis of regulatory elements across different eukaryotic taxa.
- * Identification and characterization of PAS domain-containing transcription factor complexes.
- * Examination of feedback loop mechanisms involving clock proteins like FRQ, PER, and TIM.
- * Investigation of post-transcriptional regulation and temperature sensitivity.
Main Results:
- * Common regulatory patterns were identified in eukaryotic circadian systems spanning fungi to mammals.
- * PAS domain-containing transcription factor complexes were found to positively regulate clock gene expression.
- * Clock proteins (FRQ, PER, TIM) act as negative elements, forming an oscillatory feedback loop.
- * Post-transcriptional control of FRQ influences clock responsiveness to temperature.
Conclusions:
- * Eukaryotic circadian systems are governed by conserved regulatory principles involving PAS domain transcription factors and feedback loops.
- * The interplay between transcriptional activation and post-transcriptional regulation fine-tunes circadian rhythms and temperature adaptation.
- * These findings provide a unified framework for understanding circadian clock mechanisms across eukaryotes.