Cell Size

How do cells maintain their size homeostasis?

Whether mammalian cells have size checkpoint in order to couple cell growth and cell cycle progression is a long-standing controversial question. The irregular shapes of mammalian cells and the difficulty in measuring cell size accurately have hampered study of mammanlian cell size regulation. Inspired by the earlier work of Raymond Rappaport where he studied sand dollar egg division in cylindrical channels, we developed a PDMS channel system to impose constraints in 3D. We have grown cells in the channels and observed that cells in the channel adopt cylindrical geometry, grow and divide in the fission yeast style (Varsano et al., Cell Reports 2017). Our work lead to a few surprising findings on the cell size homeostasis mechanisms, including that both cell size checkpoints and the alternative mechanism where cells add a constant amount during its G1 phases (adder) apply to mammalian cells.