CONICET | Buscador de Institutos y Recursos Humanos

Mouseembryonic stem cells (mESCs) are pluripotent cells that resemble thepreimplantation epiblast of the embryo. They can give rise to all the cells ofthe organism, which makes them an interesting cell type in the field ofregenerative medicine. Recently, the cell cycle has gained attention as a keydeterminant of their properties, based on the observation that cells onlyrespond to differentiation cues during the G1 phase. In addition, it has beenreported that mESCs possess a cell cycle length (CC-L) significantly shorterthan their differentiated counterparts. With the onset of differentiation, it hasbeen reported that CC-L increases. However, most of the research came fromexperiments that address cell populations as a whole, without considering theunderlying single-cell dynamics. In this work, we aimed to characterize thedynamics of proliferation in mESCs, both while maintaining the pluripotentstate and during differentiation. With this objective, we performed 48 htime-lapse videos of mESCs expressing the FUCCI cell cycle reporters. Wedeveloped a bioinformatic pipeline to extract single-cell dynamics of thousandsof cells, with information about their lineage relationships. Analysis of thisdatabase confirmed the short G1-L and CC-L of mESCs. It also showed that G1-Land CC-L are greatly correlated between sister cells, implying that these propertiesare partially inherited from the parental cell. We also show that during thefirst steps of differentiation, G1-L and CC-L decrease rather than increase,and that this is also accompanied by a decrease in S/G2/M-L. Along these lines,we applied Grassberger-Proccatia algorithm, that showed that the overall CC-Ldynamics is a highly deterministic process where each CC-L can be wellpredicted from each cell's lineage. By addressing the great complexity ofsingle-cell dynamics of mESCs, we believe our work contributes to a greaterunderstanding of the connection between the cell cycle and cell-fate decisions.

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