Biology

Dr. Angika Basant
Department of Molecular Genetics and Cell Biology, The University of Chicago

During cytokinesis, a small GTPase RhoA is activated by a guanine nucleotide exchange factor ECT-2 at a precise site on the plasma membrane, locally generating a contractile ring. ECT-2 is recruited to and activated by the centralspindlin complex at the central spindle, that can be at a distance from the membrane. How is RhoA activated on the membrane?

We find that a small pool of membrane-bound centralspindlin oligomers are required for RhoA activation in C. elegans embryos. Centralspindlin oligomerization and membrane binding is globally inhibited by 14-3-3/PAR-5, and 14-3-3/PAR-5 function is antagonized by Aurora B kinase during anaphase. Thus, Aurora B promotes RhoA activation via centralspindlin. We have obtained similar evidence in human cells and have built tools to optogenetically study the function of Aurora B during cytokinesis.