Wnt family members are conserved throughout the animal kingdom and participate in multiple cell fate specification events during the development of any one organism. How the Wnt pathway functions remains poorly understood, and our studies have made new and significant contributions to this important are of study. Studies of Wnt signaling in vertebrate and insect systems have suggested that Wnt signaling always activates HMG-domain proteins, but our studies show for the first time that Wnt signaling can result in different outcomes in different systems. Finally, we also have shown that Wnt signaling is required for proper orientation of the mitotic spindle in EMS during cell division. These latter results indicate that Wnt signaling can influence the polarity of the cytoskeleton, a long-suspected role for Wnt signaling but one which until now remained unproven.
ABa is to the left, ABp at the top.
Cytokinesis and cytoskeletal polarity in the early embryo. A second, more recent focus of the work in our laboratory is to understand how the completion of cytokinesis in the early embryo is coupled to the orientation of mitotic spindles during early embryonic cleavages. We have identified a gene we call cyk-1 which is specifically required for a late step in cytokinesis and which encodes a protein that is a component of both the cytokinetic cleavage furrow and of the remnant bodies left after cytokinesis is completed. We molecularly cloned cyk-1 and found that it encodes a member of the recently defined FH family of proteins. FH proteins are known to interact with the actin cytoskeleton and are involved in both cytokinesis and in polarization of the cytoskeleton in yeast and in Drosophila .