|ZFIN ID: ZDB-PUB-040319-8|
E-box function in a period gene repressed by light
Vallone, D., Gondi, S.B., Whitmore, D., and Foulkes, N.S.
|Source:||Proceedings of the National Academy of Sciences of the United States of America 101(12): 4106-4111 (Journal)|
|Registered Authors:||Foulkes, Nicholas-Simon, Vallone, Daniela, Whitmore, David|
|PubMed:||15024110 Full text @ Proc. Natl. Acad. Sci. USA|
Vallone, D., Gondi, S.B., Whitmore, D., and Foulkes, N.S. (2004) E-box function in a period gene repressed by light. Proceedings of the National Academy of Sciences of the United States of America. 101(12):4106-4111.
ABSTRACTIn most organisms, light plays a key role in the synchronization of the circadian timing system with the environmental day-night cycle. Light pulses that phase-shift the circadian clock also induce the expression of period (per) genes in vertebrates. Here, we report the cloning of a zebrafish per gene, zfper4, which is remarkable in being repressed by light. We have developed an in vivo luciferase reporter assay for this gene in cells that contain a light-entrainable clock. High-definition bioluminescence traces have enabled us to accurately measure phase-shifting of the clock by light. We have also exploited this model to study how four E-box elements in the zfper4 promoter regulate expression. Mutagenesis reveals that the integrity of these four E-boxes is crucial for maintaining low basal expression together with robust rhythmicity and repression by light. Importantly, in the context of a minimal heterologous promoter, the E-box elements also direct a robust circadian rhythm of expression that is significantly phase-advanced compared with the original zfper4 promoter and lacks the light-repression property. Thus, these results reveal flexibility in the phase and light responsiveness of E-box-directed rhythmic expression, depending on the promoter context.