Cell cycle-dependent transitions in PCP protein mobility erase and restore planar cell polarity in mitosis

Central to our understanding of how cells establish polarity is deciphering how polarity proteins are transported to and retained at asymmetric positions. Here, in the context of planar cell polarity (PCP) remodeling in mitosis where asymmetry is transiently lost and restored, we show that PCP proteins transition between mobile and stable states in coordination with cell cycle progression. Live imaging and FRAP analyses reveal that, in addition to becoming internalized into endocytic vesicles, membrane-associated PCP proteins dramatically increase their lateral mobility upon mitotic entry in a Plk1-dependent manner. Unexpectedly, asymmetry is not restored in cytokinesis via polarized delivery of PCP-protein containing vesicles. Rather, PCP proteins continue to diffuse laterally during cytokinesis where they are captured and stabilized non-cell autonomously through adhesive interactions with neighbors. We propose that a transient, laterally diffusive state in mitosis allows for flexibility and robustness in planar polarity as dividing cells change shape and rearrange.