All Light, Everywhere? Photoreceptors at Nonconventional Sites

Mat, Audrey; Vu, Hong Ha; Wolf, Eva; Tessmar-Raible, Kristin

doi:10.1152/physiol.00017.2023

Cited by 8 publications

(2 citation statements)

References 141 publications

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“…Notably, nearly no WT polyps exhibited a 12 hr rhythm under this condition, suggesting that the circadian clock overrides the light-response pathway ( Figure 5a ). While some of the circadian factors can directly sense the light, such as CRY proteins ( Mat et al, 2024 ), 29 putative NvOpsin have been identified in the genome which could be involved in the light-response pathway ( McCulloch et al, 2023 ). Behavioral tracking of NvClk Δ/Δ polyps exposed to different wavelengths could help to identify candidates for further functional studies of the light-response pathway.…”

Section: Discussionmentioning

confidence: 99%

CLOCK evolved in cnidaria to synchronize internal rhythms with diel environmental cues

Aguillon,

Rinsky,

Simon-Blecher

et al. 2024

eLife

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The circadian clock enables anticipation of the day/night cycle in animals ranging from cnidarians to mammals. Circadian rhythms are generated through a transcription-translation feedback loop (TTFL) involving negative and positive factors. CLOCK is a central conserved positive factor in the animal kingdom. However, the functional evolutionary origin and mechanism of action of CLOCK in basal animals are unknown. In cnidarians, the transcription of putative core clock genes, including Clock, is arrhythmic under constant conditions, and it is unclear how the TTFL model can regulate physiological rhythms. Here, we used the CRISPR/Cas9 system to generate a Clock mutant (Clock -/-) in Nematostella vectensis. High-throughput video tracking of locomotor activity in Clock -/- adults revealed that light regulates rhythmic behavior, while CLOCK maintains a 24-hour circadian rhythm under constant light conditions, and even under a 6-hour cycle, reminiscent of the tidal rhythm. Transcriptome profiling identified hundreds of differentially expressed genes in Clock -/- adults, particularly genes involved in cell cycle and neural development. In accordance with the rhythmic behavioral profile, computational analysis revealed rhythmic and arrhythmic gene expression in wild-type and Clock -/- adults, respectively, under constant dark conditions. Notably, hierarchal light-and Clock-signaling is required to drive rhythmic transcription of the core clock genes. These findings demonstrate that CLOCK has evolved in cnidarians to maintain synchronized 24-hour rhythmic physiology and behavior despite the chaotic inputs of environmental cues.

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Section: Discussionmentioning

confidence: 99%

CLOCK evolved in cnidaria to synchronize internal rhythms with diel environmental cues

Aguillon,

Rinsky,

Simon-Blecher

et al. 2024

eLife

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show abstract

“…5a). While some of the circadian factors can directly sense the light, such as CRY proteins 31 , 29 putative NvOpsin have been identified in the genome which could be involved in the lightresponse pathway 32 . Behavioral tracking of NvClk  polyps exposed to different wavelengths could help to identify candidates for further functional studies of the lightresponse pathway.…”

Section: Discussionmentioning

confidence: 99%

CLOCK evolved in cnidaria to synchronize internal rhythms with diel environmental cues

Rinsky

Aguillon

Simon‐Blecher

et al. 2023

Preprint

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The circadian clock is a crucial biological mechanism that enables organisms to anticipate the daily light/dark cycle. While the circadian clock factors underlying the molecular mechanism were characterized in a few model organisms, the evolutionary functional origin of the core clock proteins is unclear. In cnidarians, the expression of the putative core clock genes is rhythmic under light/dark cycles but is arrhythmic under constant light conditions. Thus, it is unclear how the core circadian genes regulate rhythmic behavior. Here, we studied the function of the evolutionarily conserved bHLH transcription factorClockin the sea anemoneNematostella vectensis. The CRISPR/Cas9 system was employed to generate aClockmutant (Clock-/-)N. vectensis. InClock-/-N. vectensis, rhythmic locomotor activity was observed under light/dark cycles, but the rhythmicity was abolished under constant dark or light conditions. Likewise, transcriptome profiling inClock-/-N. vectensisrevealed an array of clock-controlled genes (CCG). Additionally, we observed a co-operation betweenClockand light to shape core clock genes transcription rhythmicity. Notably, loss of CLOCK resulted in hundreds of differential expressed genes, which mainly regulate the cell cycle and the development of the nervous system. Overall, our results suggest that the CLOCK protein evolved to modulates the ancient hierarchy between light- and circadian clock-regulated physiology and behavior.

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