BINARY DECISION BETWEEN ASYMMETRIC AND SYMMETRIC MODE OF CELL DIVISION THROUGH THE BALANCE OF PAR POLARITY

Abstract

The ability to coordinate cell proliferation and fate diversification is a hallmark of embryonic development. Each cell chooses between asymmetric or symmetric cell division. This decision is crucial for some stem cells to perpetuate and differentiate themselves during organ homeostasis. Yet, the intrinsic program underlying these division modes remains elusive. We show that the mode of cell division in the nematode relies on the balance between two antagonizing PAR polarity complexes. Artificial manipulations of PAR protein levels can reprogram the mode of cell division, leading to all combinations of asymmetric and/or symmetric divisions during early embryogenesis. This is independent of asymmetric inheritance of fate determinants, cell size and cell cycle asynchrony between two daughter cells. We propose that the balance between two antagonizing PAR proteins provides a link between spatial control of cell polarity and the choice of cell division that the developing animal adopts.