USP2a protein deubiquitinates and stabilizes the circadian protein CRY1 in response to inflammatory signals.
The mammalian circadian clock coordinates various physiological activities with environmental cues to achieve optimal adaptation. The clock manifests oscillations of key clock proteins, which are under dynamic control at multiple post-translational levels. As a major post-translational regulator, the ubiquitination-dependent proteasome degradation system is counterbalanced by a large group of deubiquitin proteases with distinct substrate preference. Until now, whether deubiquitination by ubiquitin-specific proteases can regulate the clock protein stability and circadian pathways remains largely unclear. The mammalian clock protein, cryptochrome 1 (CRY1), is degraded via the FBXL3-mediated ubiquitination pathway, suggesting that it is also likely to be targeted by the deubiquitination pathway. Here, we identified that USP2a, a circadian-controlled deubiquitinating enzyme, interacts with CRY1 and enhances its protein stability via deubiquitination upon serum shock. Depletion of Usp2a by shRNA greatly enhances the ubiquitination of CRY1 and dampens the oscillation amplitude of the CRY1 protein during a circadian cycle. By stabilizing the CRY1 protein, USP2a represses the Per2 promoter activity as well as the endogenous Per2 gene expression. We also demonstrated that USP2a-dependent deubiquitination and stabilization of the CRY1 protein occur in the mouse liver. Interestingly, the pro-inflammatory cytokine, TNF-α, increases the CRY1 protein level and inhibits circadian gene expression in a USP2a-dependent fashion. Therefore, USP2a potentially mediates circadian disruption by suppressing the CRY1 degradation during inflammation.
Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48103, USA.
Xin
X
Tong
Katie
K
Buelow
Anirvan
A
Guha
Rebecca
R
Rausch
Lei
L
Yin
D000818:Animals; D057906:Circadian Clocks / Q000502:physiology*; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D056945:Hep G2 Cells; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D059748:Proteolysis; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D043222:Ubiquitin Thiolesterase; D054875:Ubiquitination / Q000502:physiology*
C538963:CRY1 protein, human; C538964:Cry1 protein, mouse; D056931:Cryptochromes; C421902:PER2 protein, human; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D014409:Tumor Necrosis Factor-alpha; D010450:Endopeptidases; C108665:USP2 protein, human; D043222:Ubiquitin Thiolesterase; D046988:Proteasome Endopeptidase Complex