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Vertebrate-like CRYPTOCHROME 2 from monarch regulates circadian transcription via independent repression of CLOCK and BMAL1 activity.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Zhang, Ying Markert, Matthew J. Groves, Shayna C. Hardin, Paul E. Merlin, Christine |
| Copyright Year | 2017 |
| Abstract | Circadian repression of CLOCK-BMAL1 by PERIOD and CRYPTOCHROME (CRY) in mammals lies at the core of the circadian timekeeping mechanism. CRY repression of CLOCK-BMAL1 and regulation of circadian period are proposed to rely primarily on competition for binding with coactivators on an α-helix located within the transactivation domain (TAD) of the BMAL1 C terminus. This model has, however, not been tested in vivo. Here, we applied CRISPR/Cas9-mediated mutagenesis in the monarch butterfly (Danaus plexippus), which possesses a vertebrate-like CRY (dpCRY2) and an ortholog of BMAL1, to show that insect CRY2 regulates circadian repression through TAD α-helix-dependent and -independent mechanisms. Monarch mutants lacking the BMAL1 C terminus including the TAD exhibited arrhythmic eclosion behavior. In contrast, mutants lacking the TAD α-helix but retaining the most distal C-terminal residues exhibited robust rhythms during the first day of constant darkness (DD1), albeit with a delayed peak of eclosion. Phase delay in this mutant on DD1 was exacerbated in the presence of a single functional allele of dpCry2, and rhythmicity was abolished in the absence of dpCRY2. Reporter assays in Drosophila S2 cells further revealed that dpCRY2 represses through two distinct mechanisms: a TAD-dependent mechanism that involves the dpBMAL1 TAD α-helix and dpCLK W328 and a TAD-independent mechanism involving dpCLK E333. Together, our results provide evidence for independent mechanisms of vertebrate-like CRY circadian regulation on the BMAL1 C terminus and the CLK PAS-B domain and demonstrate the importance of a BMAL1 TAD-independent mechanism for generating circadian rhythms in vivo. |
| Starting Page | E7516 |
| Ending Page | E7525 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.pnas.org/content/114/36/E7516.full.pdf |
| Alternate Webpage(s) | http://www.pnas.org/content/pnas/early/2017/08/21/1702014114.full.pdf |
| PubMed reference number | 28831003v1 |
| Alternate Webpage(s) | https://doi.org/10.1073/pnas.1702014114 |
| DOI | 10.1073/pnas.1702014114 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume Number | 114 |
| Issue Number | 36 |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | AKR1C1 wt Allele ARNTL gene CLOCK gene CRY2 gene Circadian Clocks Clustered Regularly Interspaced Short Palindromic Repeats Cryptochromes Mammals Orthologous Gene Repression, Psychology Trans-Activation, Genetic eclosion mutant |
| Content Type | Text |
| Resource Type | Article |
