Circadian Rhythms in Bmal1-/- Mouse Fibroblast Cells and Liver Tissue

Circadian clocks exist in almost all levels of living organisms and play elementary roles in the persistence of regular physiological and behavioural processes. Canonical transcription/translation feedback loop models portray BMAL1 (ARNTL) as one of the principal drivers of circadian periodicity in mammalian systems. In this integrated multi-omics study, we demonstrate, for the first time, 24 hr circadian oscillations in the expression levels of several transcripts and proteins in dexamethasone-synchronized Bmal1-/- mouse fibroblast cells and liver tissue slices. Intriguingly, daily oscillations were also observed in phosphoproteome profiles in the absence of this core clock gene. Our findings reveal that Bmal1 knockout radically alters the expression and phosphorylation patterns of mice hepatic proteome, which possibly attributes to considerably different sets of rhythmic candidates compared to wild-type. It is, therefore, reasonable to accentuate that circadian rhythms are not obliterated in mammalian systems due to deletion of the core clock genes.