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Constructing a feedback loop with circadian clock molecules from the silkmoth, Antheraea pernyi.
Dennis C Chang1, Harriet G McWatters, Julie A Williams
1Laboratory of Developmental Chronobiology, MassGeneral Hospital for Children, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
The Journal of Biological Chemistry
|July 19, 2003
Summary
The silkmoth Antheraea pernyi possesses a circadian clock mechanism similar to Drosophila, featuring a conserved feedback loop of clock genes. This suggests the autoinhibitory loop is widespread across insects, with variations in gene function.
Area of Science:
- Chronobiology
- Molecular Biology
- Insect Physiology
Background:
- Circadian clocks regulate essential physiological and behavioral processes.
- The Drosophila melanogaster circadian clock relies on a dCLOCK-dBMAL-dPERIOD-dTIMELESS autoinhibitory feedback loop.
- Emerging evidence indicates potential divergence in insect circadian clock mechanisms.
Purpose of the Study:
- To investigate the presence and function of circadian clock gene homologs in the silkmoth Antheraea pernyi.
- To determine if the autoinhibitory feedback loop mechanism found in Drosophila is conserved in A. pernyi.
- To explore the evolutionary implications of clock gene function and structure across insects.
Main Methods:
- Cloning of Clock, Bmal, and Timeless homologs from Antheraea pernyi (apClock, apBmal, apTimeless).
- Utilizing Schneider 2 (S2) cell culture assays to examine gene interactions and transcriptional activation.
- Analyzing the transactivation domain localization within clock gene proteins.
Main Results:
- apCLOCK:apBMAL complex activates transcription via the apPeriod E-box enhancer.
- apPERIOD robustly inhibits apCLOCK:apBMAL activity, with apTIMELESS augmenting this inhibition.
- A functional circadian feedback loop, analogous to Drosophila, was constructed using silkmoth clock genes.
Conclusions:
- The fundamental circadian autoinhibitory feedback loop is likely conserved across a wide range of insect species.
- The transactivation domain resides in the C terminus of apBMAL in A. pernyi, differing from Drosophila but conserved with other vertebrates and insects.
- This study provides insights into the molecular mechanisms and evolutionary history of circadian clock genes in the animal kingdom.