CK2α phosphorylates BMAL1 to regulate the mammalian clock

Clock proteins govern circadian physiology and their function is regulated by various mechanisms. Here we demonstrate that Casein kinase (CK)-2 alpha phosphorylates the core circadian regulator BMAL1. Gene silencing of CK2 alpha or mutation of the highly conserved CK2-phosphorylation site in BMAL1, Ser90, result in impaired nuclear BMAL1 accumulation and disruption of clock function. Notably, phosphorylation at Ser90 follows a rhythmic pattern. These findings reveal that CK2 is an essential regulator of the mammalian circadian system.