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QUASIMODO, a Novel GPI-anchored zona pellucida protein involved in light input to the Drosophila circadian clock.

Chen, KF; Peschel, N; Zavodska, R; Sehadova, H; Stanewsky, R; (2011) QUASIMODO, a Novel GPI-anchored zona pellucida protein involved in light input to the Drosophila circadian clock. Curr Biol , 21 (9) pp. 719-729. 10.1016/j.cub.2011.03.049.

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Abstract

BACKGROUND: Circadian clocks are synchronized to the solar day via visual and specialized photoreceptors. In Drosophila, CRYPTOCHROME (CRY) is a major photoreceptor that mediates resetting of the circadian clock via light-dependent degradation of the clock protein TIMELESS (TIM). However, in the absence of CRY, this TIM-mediated resetting still occurs in some pacemaker neurons, resulting in synchronized behavioral rhythms when flies are exposed to light-dark cycles. Even in the additional absence of visual photoreception, partial molecular and behavioral light synchronization persists. Therefore, other important clock-related photoreceptive and synchronization mechanisms must exist. RESULTS: We identified a novel clock-controlled gene (quasimodo) that encodes a light-responsive and membrane-anchored Zona Pellucida domain protein that supports light-dependent TIM degradation. Whereas wild-type flies become arrhythmic in constant light (LL), quasimodo mutants elicit rhythmic expression of clock proteins and behavior in LL. QUASIMODO (QSM) can function independently of CRY and is predominantly expressed within CRY-negative clock neurons. Interestingly, downregulation of qsm in the clock circuit restores LL clock protein rhythms in qsm-negative neurons, indicating that qsm-mediated light input is not entirely cell autonomous and can be accessed by the clock circuit. CONCLUSIONS: Our findings indicate that QSM constitutes part of a novel and CRY-independent light input to the circadian clock. Like CRY, this pathway targets the clock protein TIM. QSM's light-responsive character in conjunction with the predicted localization at the outer neuronal membrane suggests that its function is linked to a yet unidentified membrane-bound photoreceptor.

Type: Article
Title: QUASIMODO, a Novel GPI-anchored zona pellucida protein involved in light input to the Drosophila circadian clock.
Location: England
DOI: 10.1016/j.cub.2011.03.049
Keywords: Animals, Animals, Genetically Modified, Blotting, Western, Brain, Circadian Clocks, Cloning, Molecular, DNA Primers, Drosophila, Drosophila Proteins, GPI-Linked Proteins, Genotype, Immunohistochemistry, Light Signal Transduction, Microscopy, Fluorescence, Neurons, Photoperiod, Polymerase Chain Reaction, RNA Interference, Zona Pellucida
UCL classification: UCL > School of Life and Medical Sciences
UCL > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Neurology
UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Neurology > Clinical and Experimental Epilepsy
UCL > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > School of Life and Medical Sciences > Faculty of Life Sciences > Biosciences (Division of) > Cell and Developmental Biology
URI: http://discovery.ucl.ac.uk/id/eprint/1402372
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