Abstract

Cell cycle kinetics are crucial to cell fate decisions. Although live imaging has provided extensive insights into this relationship at the single-cell level, the limited number of fluorescent markers that can be used in a single experiment has hindered efforts to link the dynamics of individual proteins responsible for decision making directly to cell cycle progression. I will present an all-in-one cell cycle reporter that allows simultaneous analysis of cell cycle progression, including the transition into quiescence, and the dynamics of individual fate determinants. Focusing on cyclin D1 as a major cell cycle regulator, we present evidence that a crucial cell cycle function of cyclin D1 is to prevent the transition into quiescence and identify a unique cyclin D1 protein kinetics that are indicative of very short G1 phases. In addition, to allow manipulating the levels of endogenous proteins at will, we introduce a novel approach to render already existing GFP (trap) lines amenable to auxin-dependent degradation by simple ectopic expression of a degradation cassette using human cells and zebrafish as a proofs of principle.