Feedback repression is required for mammalian circadian clock function

TK Sato, RG Yamada, H Ukai, JE Baggs, LJ Miraglia… - Nature …, 2006 - nature.com
TK Sato, RG Yamada, H Ukai, JE Baggs, LJ Miraglia, TJ Kobayashi, DK Welsh, SA Kay
Nature genetics, 2006nature.com
Direct evidence for the requirement of transcriptional feedback repression in circadian clock
function has been elusive. Here, we developed a molecular genetic screen in mammalian
cells to identify mutants of the circadian transcriptional activators CLOCK and BMAL1, which
were uncoupled from CRYPTOCHROME (CRY)-mediated transcriptional repression.
Notably, mutations in the PER-ARNT-SIM domain of CLOCK and the C terminus of BMAL1
resulted in synergistic insensitivity through reduced physical interactions with CRY …
Abstract
Direct evidence for the requirement of transcriptional feedback repression in circadian clock function has been elusive. Here, we developed a molecular genetic screen in mammalian cells to identify mutants of the circadian transcriptional activators CLOCK and BMAL1, which were uncoupled from CRYPTOCHROME (CRY)-mediated transcriptional repression. Notably, mutations in the PER-ARNT-SIM domain of CLOCK and the C terminus of BMAL1 resulted in synergistic insensitivity through reduced physical interactions with CRY. Coexpression of these mutant proteins in cultured fibroblasts caused arrhythmic phenotypes in population and single-cell assays. These data demonstrate that CRY-mediated repression of the CLOCK/BMAL1 complex activity is required for maintenance of circadian rhythmicity and provide formal proof that transcriptional feedback is required for mammalian clock function.
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