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    目:The hunt for cell size sensors: Mechanisms controlling cell size in animal cells?

报告人:Dr. Shixuan Liu

Sickkids Research Institute, and Department of Molecular Genetics, University of Toronto



主持人:汤超 教授



  Although questions on cell size have been investigated for more than half a century, molecular mechanisms that ‘program’ the size of animal cells are only starting to be revealed. My research focuses on the molecular mechanisms that promote cell size uniformity in proliferating mammalian cells. By relying on a high-content small chemical screen, I identified candidate proteins and signaling molecules that may function as cell size specifiers. Intriguingly, analysis of the screen hits suggested a role for the p38 MAPK in the long-sought mammalian cell size checkpoint. Follow-up experiments further showed that p38 MAPK signaling is activated in small, but not large cells, which selectively inhibits the progression of small cells into S phase. Consistent with this model, chemical and genetic perturbations of p38 resulted in the loss of the compensatory G1 length extension in small cells; cells lacking p38 activity proliferated faster, were smaller in size and displayed increased size heterogeneity. This work suggests a model whereby the p38 MAPK pathway responds to changes in cell size and regulates G1 exit accordingly, to increase cell size uniformity.



  Dr. Shixuan received her B.S. in Biology at Peking University in 2013. She just got her Ph.D. in Systems Biology at University of Toronto in 2019 and will move to Stanford for a postdoc with Jim Ferrell and Mark Krasnow. Dr. Shixuan Liu studies the molecular mechanisms of cell size control in mammalian cells, with a focus on the mechanisms coordinating cellular growth and cell cycle.