SCFbeta-TRCP controls clock-dependent transcription via casein kinase 1-dependent degradation of the mammalian period-1 (Per1) protein.
Circadian rhythms are controlled by the periodic accumulation of Period proteins, which act as transcriptional repressors of Clock-dependent genes. Period genes are themselves Clock targets, thereby establishing a negative transcriptional feedback circuit controlling circadian periodicity. Previous data have implicated the CK1epsilon isolog Doubletime (Dbt) and the F-box protein Slimb in the regulation of Drosophila Period (Per) through an unknown mechanism. In this work, we have identified components of the machinery involved in regulating the abundance of human Per1 in tissue culture cells. CK1epsilon and CK1gamma2 were found to bind to Per1 and to promote its degradation in an in vivo degradation assay. Per1 turnover was blocked by a dominant negative version of the Cul1 protein, a component of the SCF (Skp1-Cul1-F-box protein) ubiquitin ligase. We screened a panel of F-box proteins for those that would associate with Per1 in a CK1epsilon-dependent manner, and we identified beta-TRCP1 and beta-TRCP2, isologs of the Drosophila Slimb protein. RNA interference against beta-transducin repeat-containing protein (beta-TRCP) stabilizes endogenous and exogenous Per1. beta-TRCP associates with sequences near the N terminus of Per1 in a region distinct from the previously characterized CK1epsilon-binding site. beta-TRCP and CK1epsilon promote Per1 ubiquitination in vitro. Finally, RNA interference against beta-TRCP greatly decreases Clock-dependent gene expression in tissue culture cells, indicating that beta-TRCP controls endogenous Per1 activity and the circadian clock by directly targeting Per1 for degradation.
Shirogane
Takahiro
T
Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Jin
Jianping
J
Ang
Xiaolu L
XL
Harper
J Wade
JW
D001665:Binding Sites; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D002460:Cell Line; D002940:Circadian Rhythm; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism*; D056950:Period Circadian Proteins; D044843:SKP Cullin F-Box Protein Ligases / Q000502:physiology*; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D044844:beta-Transducin Repeat-Containing Proteins / Q000502:physiology*
C471644:BTRC protein, human; D018797:Cell Cycle Proteins; C471645:FBXW11 protein, human; D009687:Nuclear Proteins; C539022:PER1 protein, human; D056950:Period Circadian Proteins; D015534:Trans-Activators; D025801:Ubiquitin; D044844:beta-Transducin Repeat-Containing Proteins; D056926:CLOCK Proteins; C538943:CLOCK protein, human; D044843:SKP Cullin F-Box Protein Ligases; D044767:Ubiquitin-Protein Ligases