CRY2 and FBXL3 cooperatively degrade c-MYC #MMPMID27840026
Huber AL; Papp SJ; Chan AB; Henriksson E; Jordan SD; Kriebs A; Nguyen M; Wallace M; Li Z; Metallo CM; Lamia KA
Mol Cell 2016[Nov]; 64 (4): 774-89 PMID27840026show ga
For many years, a connection between circadian clocks and cancer has been postulated. Here, we describe an unexpected function for the circadian repressor CRY2 as a component of an FBXL3-containing E3 ligase that recruits T58-phosphorylated c-MYC for ubiquitylation. c-MYC is a critical regulator of cell proliferation; T58 is central in a phosphodegron long recognized as a hotspot for mutation in cancer. This site is also targeted by FBXW7, though the full machinery responsible for its turnover has remained obscure. CRY1 cannot substitute for CRY2 in promoting c-MYC degradation; their unique functions may explain prior conflicting reports that have fueled uncertainty about the relationship between clocks and cancer. Thus, we demonstrate that c-MYC is a target of CRY2-dependent protein turnover, suggesting a molecular mechanism for circadian control of cell growth and a new paradigm for circadian protein degradation.