ZFIN ID: ZDB-PUB-150324-1
The Zebrafish Period2 Protein Positively Regulates the Circadian Clock through Mediation of Retinoic Acid Receptor (RAR)-related Orphan Receptor α (Rorα)
Wang, M., Zhong, Z., Zhong, Y., Zhang, W., Wang, H.
Date: 2015
Source: The Journal of biological chemistry   290(7): 4367-4382 (Journal)
Registered Authors: Wang, Han, Zhang, Wei
Keywords: Circadian Clock, Gene Regulation, Rev-ErbAα (NR1D1), Transgenic, Zebrafish, Rorα, Period2
MeSH Terms:
  • ARNTL Transcription Factors/genetics
  • ARNTL Transcription Factors/metabolism*
  • Animals
  • Blotting, Western
  • Chromatin Immunoprecipitation
  • Circadian Clocks/physiology*
  • Embryo, Nonmammalian
  • Eye Proteins/genetics
  • Eye Proteins/metabolism*
  • Immunoenzyme Techniques
  • Mice
  • Motor Activity
  • Period Circadian Proteins/genetics
  • Period Circadian Proteins/metabolism*
  • RNA, Messenger/genetics
  • Real-Time Polymerase Chain Reaction
  • Receptors, Cytoplasmic and Nuclear/genetics
  • Receptors, Cytoplasmic and Nuclear/metabolism*
  • Receptors, Retinoic Acid/genetics
  • Receptors, Retinoic Acid/metabolism*
  • Response Elements/genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcriptional Activation
  • Zebrafish
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
PubMed: 25544291 Full text @ J. Biol. Chem.

We report the characterization of a null mutant for zebrafish circadian clock gene period2 (per2) generated by transcription activator-like effector nuclease and a positive role of PER2 in vertebrate circadian regulation. Locomotor experiments showed that per2 mutant zebrafish display reduced activities under light-dark and 2-h phase delay under constant darkness, and quantitative real time PCR analyses showed up-regulation of cry1aa, cry1ba, cry1bb, and aanat2 but down-regulation of per1b, per3, and bmal1b in per2 mutant zebrafish, suggesting that Per2 is essential for the zebrafish circadian clock. Luciferase reporter assays demonstrated that Per2 represses aanat2 expression through E-box and enhances bmal1b expression through the Ror/Rev-erb response element, implicating that Per2 plays dual roles in the zebrafish circadian clock. Cell transfection and co-immunoprecipitation assays revealed that Per2 enhances bmal1b expression through binding to orphan nuclear receptor Rorα. The enhancing effect of mouse PER2 on Bmal1 transcription is also mediated by ROR± even though it binds to REV-ERBα. Moreover, zebrafish Per2 also appears to have tissue-specific regulatory roles in numerous peripheral organs. These findings help define the essential functions of Per2 in the zebrafish circadian clock and in particular provide strong evidence for a positive role of PER2 in the vertebrate circadian system.