Ectopic CRYPTOCHROME Renders TIM Light Sensitive in the Drosophila Ovary

Rush, B. L.; Murad, Alejandro D.; Emery, Patrick; Giebułtowicz, Jadwiga M.

doi:10.1177/0748730406290416

Cited by 30 publications

(30 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While the nonoscillatory nature of the core clock proteins may be due to the absence of positive feedback elements, CLOCK and CYCLE expression, or due to the absence of CRYPTOCHROME (CRY) in the ovary (Beaver et al 2003), what remains to be discovered is what mechanisms generate rhythmic signals for egg-laying? Interestingly, ectopic expression of CRY in the ovaries results in circadian oscillation of the per and tim genes in the negative feedback loop of the molecular clock (Rush et al 2006). Other studies have also shown that loss of function per and tim mutant females exhibit reduced reproductive output (Beaver et al 2003).…”

Section: Entrainment Of the Egg-laying Rhythmmentioning

confidence: 98%

Egg-laying rhythm in Drosophila melanogaster

Manjunatha

Dass

Sharma

2008

J Genet

View full text Add to dashboard Cite

Extensive research has been carried out to understand how circadian clocks regulate various physiological processes in organisms. The discovery of clock genes and the molecular clockwork has helped researchers to understand the possible role of these genes in regulating various metabolic processes. In Drosophila melanogaster, many studies have shown that the basic architecture of circadian clocks is multi-oscillatory. In nature, different neuronal subgroups in the brain of D. melanogaster have been demonstrated to control different circadian behavioural rhythms or different aspects of the same circadian rhythm. Among the circadian phenomena that have been studied so far in Drosophila, the egg-laying rhythm is unique, and relatively less explored. Unlike most other circadian rhythms, the egg-laying rhythm is rhythmic under constant light conditions, and the endogenous or free-running period of the rhythm is greater than those of most other rhythms. Although the clock genes and neurons required for the persistence of adult emergence and activity/rest rhythms have been studied extensively, those underlying the circadian egg-laying rhythm still remain largely unknown. In this review, we discuss our current understanding of the circadian egg-laying rhythm in D. melanogaster, and the possible molecular and physiological mechanisms that control the rhythmic output of the egg-laying process.

show abstract

Section: Entrainment Of the Egg-laying Rhythmmentioning

confidence: 98%

Egg-laying rhythm in Drosophila melanogaster

Manjunatha

Dass

Sharma

2008

J Genet

View full text Add to dashboard Cite

show abstract

“…Brains were dissected on day 6 of the TC at the indicated time points. Primary rat anti-TIM (1:1000) 37 , and secondary rat AlexaFluor-594 antibodies (Invitrogen, 1:500) were applied. Mounted brains were scanned using a Leica TCS SP5 confocal microscope.…”

Section: Immunostaining and Quantificationmentioning

confidence: 99%

Drosophila Ionotropic Receptor 25a mediates circadian clock resetting by temperature

Chen

Buhl

et al. 2015

Nature

164

177

View full text Add to dashboard Cite

Summary:Circadian clocks are endogenous timers adjusting behaviour and physiology with the solar day 1 .Synchronized circadian clocks improve fitness 2 and are crucial for our physical and mental wellbeing 3 . Visual and non-visual photoreceptors are responsible for synchronizing circadian clocks to light 4,5 , but clock-resetting is also achieved by alternating day and night temperatures with only 2°-4°C difference [6][7][8] . This temperature sensitivity is remarkable considering that the circadian clock period (~24 h) is largely independent of surrounding ambient temperatures 1,8 .Here we show that Drosophila Ionotropic Receptor 25a (IR25a) is required for behavioural synchronization to low-amplitude temperature cycles. This channel is expressed in sensory neurons of internal stretch receptors previously implicated in temperature synchronization of the circadian clock 9 . IR25a is required for temperature-synchronized clock protein oscillations in subsets of central clock neurons. Extracellular leg nerve recordings reveal temperature -and IR25a-dependent sensory responses, and IR25a mis-expression confers temperature-dependent firing of heterologous neurons. We propose that IR25a is part of an input pathway to the circadian clock that detects small temperature differences. This pathway operates in the absence of known 'hot' and 'cold' sensors in the Drosophila antenna 10,11 , revealing the existence of novel periphery-to-brain temperature signalling channels. Main Text:In Drosophila, daily activity rhythms are controlled by a network of ~150 clock neurons expressing the clock genes period (per) and timeless (tim). These encode repressor proteins that 3 negatively feedback on their own promoters resulting in 24 h oscillations of clock molecules.Temperature cycles (TC) synchronise molecular clocks present in peripheral appendages in a tissue-autonomous manner 9,12 , while synchronization of clock neurons in the brain largely depends on peripheral temperature receptors located in the chordotonal organs (ChO) and the ChO-expressed gene nocte 9,12,13 .To discover novel factors involved in temperature entrainment, we identified NOCTEinteracting proteins by co-immunoprecipitation and mass-spectrometry (Extended Data Tab. 1) 14 . We focused on IR25a, a member of a divergent subfamily of ionotropic glutamate receptors and verified the interaction by co-immunoprecipitation after overexpressing IR25a and NOCTE in all clock cells using tim-gal4 (Extended Data Fig. 1a). IR25a is expressed in different populations of sensory neurons, including those in the antenna and labellum [15][16][17] . In the olfactory system IR25a acts as a co-receptor with different odour-sensing IRs 15 .To investigate if IR25a is co-expressed with nocte in ChO we analysed IR25a expression in femur and antennal ChO using an IR25a-gal4 line 15 (Extended Data Fig. 2a). IR25a-gal4 driven mCD8-GFP labelled subsets of ChO neurons in the femur, overlapping substantially with nompC-QF driven QUAS-Tomato signals (Fig. 1 a-c). nompC-QF is expressed in larv...

show abstract

“…Ten adult heads were collected for each genotype, and similar Western methods were followed for fly head extracts as described above. Rabbit anti-CRY antibody (Rush et al 2006) was used to probe endogenous CRY. TIM and HSP-70 levels were determined as described above.…”

Section: Western Blot Analysis For Adult Fliesmentioning

confidence: 99%

Identification of novel genes involved in light-dependent CRY degradation through a genome-wide RNAi screen

Sathyanarayanan¹,

Zheng²,

Kumar³

et al. 2008

Genes Dev.

View full text Add to dashboard Cite

Circadian clocks regulate many different physiological processes and synchronize these to environmental light:dark cycles. In Drosophila, light is transmitted to the clock by a circadian blue light photoreceptor CRYPTOCHROME (CRY). In response to light, CRY promotes the degradation of the circadian clock protein TIMELESS (TIM) and then is itself degraded. To identify novel genes involved in circadian entrainment, we performed an unbiased genome-wide screen in Drosophila cells using a sensitive and quantitative assay that measures light-induced degradation of CRY. We systematically knocked down the expression of ∼21,000 genes and identified those that regulate CRY stability. These genes include ubiquitin ligases, signal transduction molecules, and redox molecules. Many of the genes identified in the screen are specific for CRY degradation and do not affect degradation of the TIM protein in response to light, suggesting that, for the most part, these two pathways are distinct. We further validated the effect of three candidate genes on CRY stability in vivo by assaying flies mutant for each of these genes. This work identifies a novel regulatory network involved in light-dependent CRY degradation and demonstrates the power of a genome-wide RNAi approach for understanding circadian biology.[Keywords: RNAi; circadian rhythms; clock proteins; degradation; photoreceptors] Supplemental material is available at http://www.genesdev.org. The cycling of PER and TIM is essential for circadian rhythms and is thought to provide timekeeping cues for the organism. Consistent with the idea that levels of PER-TIM constitute time-of-day signals, light sets the time of the clock by altering levels of these molecules. Thus, entrainment of the molecular clock to light is mediated by light-induced degradation of the TIM protein.In response to light, TIM is targeted to the ubiquitinproteasome pathway by an E3 ubiquitin ligase complex containing the F-box protein JETLAG (JET) (Naidoo et al. 1999;Koh et al. 2006). The ubiquitin-proteasome pathway may also affect light-independent PER-TIM degradation, which maintains cycling under free-running conditions (Grima et al. 2002;Ko et al. 2002). Degradation of TIM in response to light, as well as in free-running conditions, is affected by its phosphorylation state (Zeng et al. 1996;Naidoo et al. 1999;Grima et al. 2002;Yuan et al. 2005).Photic signals are transmitted to TIM by a dedicated circadian photoreceptor, CRYPTOCHROME (CRY) (Cashmore 2003;Lin and Todo 2005). After signaling to TIM, CRY is itself degraded by the proteasome pathway (Lin et al. 2001), However the role of light-dependent CRY degradation in regulating circadian behavior and resetting is not clear. According to one report, clock neuron-specific overexpression of CRY increases circadian photo sensitivity (Emery et al. 2000), while another study found that overexpression of CRY reduces photo sensitivity (Ishikawa et al. 1999). A CRY mutant (CRY m ) lacking the C-terminal domain required for the regula-

show abstract

Ectopic CRYPTOCHROME Renders TIM Light Sensitive in the Drosophila Ovary

Cited by 30 publications

References 41 publications

Egg-laying rhythm in Drosophila melanogaster

Egg-laying rhythm in Drosophila melanogaster

Drosophila Ionotropic Receptor 25a mediates circadian clock resetting by temperature

Identification of novel genes involved in light-dependent CRY degradation through a genome-wide RNAi screen

Contact Info

Product

Resources

About