12:15 pm
KPTC Room 206
"Tissue confinement governs cell size regulation in epithelial tissue"
While populations of single-celled organisms increase exponentially, animal cell growth must be coupled to organism growth for tissues to maintain their structure. These spatial constraints lead to a different regime of growth and division regulation known as contact inhibition of proliferation. We still lack a general framework to describe contact inhibition across different biological systems. Here we use model epithelial monolayers with varying spatial constraints to explore how contact inhibition affects cell growth and division. We introduce a concept of tissue confinement which describes the extent to which spatial constraints suppress cell growth in different tissues. Interestingly, confinement has no effect on cell division leading to a decoupling between rates of cell growth and division. In confined tissues cell division outpaces growth causing cell size to decrease. However, when cell size decreases below a specific value cell division becomes arrested. This final cell size is near a physical limit set by the amount of space occupied by DNA in the cell. By perturbing cell division regulation, it is possible to push cells closer to this limit, however, this leads to DNA damage suggesting loss of size regulation could play a role in the development of cancer.