From timekeeping to divisions—Molecular links between circadian rhythms and cell cycle

Circadian rhythms and the cell cycle are two fundamental biological oscillators. They are linked through molecular mechanisms creating coupled oscillators where the outcomes of this coupling depend on numerous factors, such as the directionality of coupling (i.e., unidirectional vs. bidirectional), periods of the two oscillators, and the number and strength of connections. In this review, we provide a general overview of the links between circadian rhythms and the cell cycle and discuss potential implications of this connection in stem cell proliferation and differentiation of mammalian cells.