Figure 7. PAR-3 oligomerization is negatively regulated by PLK-1.

A) Kymographs of cortical mNG::PAR-3 in wild-type and plk-1(RNAi) embryos. Anterior is to the left. Horizontal scale bar represents 10 μm and vertical scale bar represents 1 min.

B) Yeast two hybrid assays examining the interaction between PAR-3N (amino acids 1–394) and the PBD of PLK-1. Colonies transformed with the indicated plasmids were grown on non-selective or selective medium. Growth on selective medium indicates an interaction.

C) Autoradiograph (top) and comassie stained gel (bottom) showing phosphorylation of PAR-3N by PLK-1. The red asterisks at around 72 kDa indicate PLK-1 autophosphorylation in the autioradiograph and PLK-1 loading in the Comassie stained gel.

D) Distribution of oligomer sizes for PAR-3 WT and T32E, T89E during establishment phase. The WT data from Figure 3B are presented again here to facilitate comparison. n = 4,741 molecules counted from 9 embryos for WT and n = 9,658 molecules counted from 4 embryos for T32E, T89E.

E) Localization of mNG::PAR-3(T32E, T89E) at the indicated embryonic stages.

F) Quantification of cleavage furrow position in wild-type and the par-3(T32E, T89E) mutant. The wild-type data from Figure 5E are presented again here to facilitate comparison.

G) Kymographs of cortical mNG::PAR-3 during maintenance phase in a wild-type embryo and an embryo partially depleted of PLK-1 using feeding RNAi. Anterior is to the left. Horizontal scale bar represents 10 μm and vertical scale bar represents 1 min. The timing of cellular events that define the beginning and end of maintenance phase are labeled; PNM, pronuclear meeting. Note that maintenance phase is slightly longer after treatment with plk-1 RNAi, most likely because depletion of PLK-1 results in a cell cycle delay.

H) Model for regulation of polarity establishment by PAR-3 oligomerization. PAR-3 oligomers recruit PAR-6 and aPKC during polarity establishment, forming functional units that couple to cortical flow and are transported to the anterior to establish polarity. By negatively regulating PAR-3 oligomerization, PLK-1 links PAR-3 oligomerization to the cell cycle and restricts PAR complex transport to the correct developmental time.

See also Figures S4, S5 and S7.