Wang, P.-K.; Lin, K.-h.; Tang, T. K.

Polarization is crucial for the proper functioning of epithelial cells. Early polarization features include the trafficking and enrichment of polarity molecules to form the apical membrane (AM) or cell-cell junctions, as well as the apical positioning of the centrosome. However, the dependencies among polarity molecules, AM formation, and centrosome positioning remain poorly understood. In conventional Matrigel-cultured epithelial cells, de novo polarization can occur when a single cell divides. At the exit of mitosis, centrosomes move to the location where the apical membrane will form, raising the question of the role of the centrosome in epithelial polarization. We perturb centrosomes and polarity regulators in Matrigel-cultured cells and also manipulate polarity direction in non-conventional culture to examine the relationship between polarity features. Surprisingly, the centrosome is not essential for AM formation but promotes formation efficiency. The polarity regulator Par3, rather than the trafficking of AM components, affects centrosome positioning. In non-conventional cultures, the centrosome migration is opposite to that of the AM direction, and Par3 exhibits a different pattern from Matrigel culture. Taken together, our work shows that polarity indicated by centrosome position is not universal and elucidates the upstream-downstream relationship between centrosome positioning and other polarization features, providing insights into epithelial polarization.