Uncovering the role of cell size asymmetry in Drosophila neuroblasts

How does a stem cell produce two daughters with different identities? Current models emphasise that unequal inheritance of molecules determines ganglion mother cell (GMC) fate in the developing Drosophila central nervous system. This ensures that one daughter, the neuroblast, retains stem cell identity while the GMC embarks on differentiation. But what if something as simple as cell size could override these molecular instructions?

Drosophila neural stem cells, called neuroblasts, this process generates daughters that differ in fate but also dramatically in size. Understanding how this physical asymmetry emerges reveals an intricate interplay between cell polarity, cortical mechanics and membrane dynamics. Spatially controlled actomyosin contractility and local membrane expansion work together to shape dividing cells, translating molecular organisation into differences in daughter-cell size.

Intriguingly, cell size is more than a passive consequence of asymmetric division. It can actively influence developmental decisions, even challenging the instructions provided by inherited fate determinants. At least in the type I neuroblast lineage size seems integral to how the identity of ganglion mother cells are specified.

In this seminar I will summarise our findings and sketch our direction of travel on the regulation of cell size asymmetry and its contribution on cell fate.