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Cell. 2007 Jun 1;129(5):1011-23. Epub 2007 Apr 26.

Circadian mutant Overtime reveals F-box protein FBXL3 regulation of cryptochrome and period gene expression.

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  • 1Howard Hughes Medical Institute, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA.

Abstract

Using a forward genetics ENU mutagenesis screen for recessive mutations that affect circadian rhythmicity in the mouse, we isolated a long period (approximately 26 hr) circadian mutant named Overtime (Ovtm). Positional cloning and genetic complementation reveal that Ovtm is encoded by the F-box protein FBXL3, a component of the SKP1-CUL1-F-box-protein (SCF) E3 ubiquitin ligase complex. The Ovtm mutation causes an isoleucine to threonine (I364T) substitution leading to a loss of function in FBXL3, which interacts specifically with the CRYPTOCHROME (CRY) proteins. In Ovtm mice, expression of the PERIOD proteins PER1 and PER2 is reduced; however, the CRY proteins CRY1 and CRY2 are unchanged. The loss of FBXL3 function leads to a stabilization of the CRY proteins, which in turn leads to a global transcriptional repression of the Per and Cry genes. Thus, Fbxl3(Ovtm) defines a molecular link between CRY turnover and CLOCK/BMAL1-dependent circadian transcription to modulate circadian period.

PMID:
17462724
[PubMed - indexed for MEDLINE]
PMCID:
PMC3762874
Free PMC Article
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