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JETLAG Resets the Drosophila Circadian Clock by Promoting Light-Induced Degradation of TIMELESS
Kyunghee Koh,Xiangzhong Zheng,Amita Sehgal*
Organisms ranging from bacteria to humans synchronize theirinternal clocks to daily cycles of light and dark. Photic entrainmentof the Drosophila clock is mediated by proteasomal degradationof the clock protein TIMELESS (TIM). We have identified mutationsin jetlaga gene coding for an F-box protein with leucine-richrepeatsthat result in reduced light sensitivity of thecircadian clock. Mutant flies show rhythmic behavior in constantlight, reduced phase shifts in response to light pulses, andreduced light-dependent degradation of TIM. Expression of JETalong with the circadian photoreceptor cryptochrome (CRY) incultured S2R cells confers light-dependent degradation ontoTIM, thereby reconstituting the acute response + of the circadianclock to light in a cell culture system. Our results suggestthat JET is essential for resetting the clock by transmittinglight signals from CRY to TIM.
Howard Hughes Medical Institute, Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
* To whom correspondence should be addressed. E-mail: amita{at}mail.med.upenn.edu
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Veela defines a molecular link between Cryptochrome and Timeless in the light-input pathway to Drosophila's circadian clock.