Lineage Specification from Prostate Progenitor Cells Requires Gata3-Dependent Mitotic Spindle Orientation

During prostate development, basal and luminal cell lineages are generated through symmetric and asymmetric divisions of bipotent basal cells. However, the extent to which spindle orientation controls division symmetry or cell fate, and the upstream factors regulating this process, are still elusive. We report that GATA3 is expressed in both prostate basal progenitor and luminal cells and that loss of GATA3 leads to a mislocalization of PRKCZ, resulting in mitotic spindle randomization during progenitor cell division. Inherently proliferative intermediate progenitor cells accumulate, leading to an expansion of the luminal compartment. These defects ultimately result in a loss of tissue polarity and defective branching morphogenesis. We further show that disrupting the interaction between PRKCZ and PARD6B is sufficient to recapitulate the spindle and cell lineage phenotypes. Collectively, these results identify a critical role for GATA3 in prostate lineage specification, and further highlight the importance of regulating spindle orientation for hierarchical cell lineage organization.