Kinesin-1 patterns Par-1 and Rho signaling at the cortex of syncytial embryos of Drosophila.

The cell cortex of syncytial Drosophila embryos is patterned into cap and intercap regions by centrosomes, specific sets of proteins that are restricted to their respective regions by unknown mechanisms. Here, we found that Kinesin-1 is required for the restriction of plus- and minus-ends of centrosomal and non-centrosomal microtubules to the cap region, marked by EB1 and Patronin/Shot, respectively. Kinesin-1 also directly or indirectly restricts proteins and Rho signaling to the intercap, including the RhoGEF Pebble, Dia, Myosin II, Capping protein-α, and the polarity protein Par-1. Furthermore, we found that Par-1 is required for cap restriction of Patronin/Shot, and vice versa Patronin, for Par-1 enrichment at the intercap. In summary, our data support a model that Kinesin-1 would mediate the restriction of centrosomal and non-centrosomal microtubules to a region close to the centrosomes and exclude Rho signaling and Par-1. In addition, mutual antagonistic interactions would refine and maintain the boundary between cap and intercap and thus generate a distinct cortical pattern.