Par3–mInsc and Gαi3 cooperate to promote oriented epidermal cell divisions through LGN

The study investigated the role of LGN-interacting proteins Par3, mInsc, and Gαi3 in regulating oriented cell divisions during murine epidermal development. Using genetics and RNAi techniques, researchers found that the loss of each gene individually led to randomized division angles, while the combined loss of Gnai3 and mInsc resulted in mostly planar divisions, similar to the loss of LGN. This supported the model that Par3–mInsc and Gαi3 cooperatively polarized LGN to promote perpendicular divisions. Additionally, the study identified a developmental switch around embryonic day 15 (E15) from delamination-driven stratification to spindle-orientation-dependent differentiation, suggesting a two-step mechanism in epidermal maturation.