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USP2a protein deubiquitinates and stabilizes the circadian protein CRY1 in response to inflammatory signals

Xin Tong1, Katie Buelow, Anirvan Guha

  • 1Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48103, USA.

The Journal of Biological Chemistry
|June 7, 2012
PubMed

Insights

Ubiquitin-specific protease 2a (USP2a) stabilizes the core circadian clock protein cryptochrome 1 (CRY1) by removing ubiquitin tags. This regulation impacts circadian rhythm amplitude and gene expression, particularly during inflammation.

Area of Science:

  • Molecular Biology
  • Chronobiology
  • Biochemistry

Background:

  • The mammalian circadian clock relies on rhythmic protein oscillations, regulated by post-translational modifications like ubiquitination and deubiquitination.
  • Ubiquitin-specific proteases (USPs) counteract proteasomal degradation, but their role in circadian clock protein stability is largely unknown.
  • Cryptochrome 1 (CRY1), a key clock protein, is degraded through the FBXL3-mediated ubiquitination pathway.

Purpose of the Study:

  • To investigate whether deubiquitination by USP2a regulates CRY1 stability and circadian pathways.
  • To elucidate the mechanism by which USP2a affects CRY1 protein levels and circadian gene expression.
  • To explore the role of USP2a in mediating circadian disruption during inflammation.

Main Methods:

  • Interaction studies between USP2a and CRY1.
  • Assessment of CRY1 ubiquitination and stability upon USP2a depletion (shRNA).
  • Analysis of Per2 promoter activity and gene expression.
  • Investigation in mouse liver models and response to TNF-α.

Main Results:

  • USP2a interacts with CRY1 and enhances its stability through deubiquitination.
  • USP2a depletion increases CRY1 ubiquitination and dampens its circadian oscillation amplitude.
  • USP2a stabilizes CRY1, leading to repression of Per2 promoter activity and gene expression.
  • USP2a-mediated CRY1 stabilization occurs in mouse liver and is influenced by TNF-α.

Conclusions:

  • USP2a is a circadian-controlled deubiquitinating enzyme that stabilizes CRY1, thereby regulating circadian rhythms.
  • USP2a plays a role in suppressing CRY1 degradation, impacting circadian gene expression.
  • The pro-inflammatory cytokine TNF-α can disrupt circadian rhythms via a USP2a-dependent mechanism by stabilizing CRY1.

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