The spatiotemporal distribution of LIN-5/NuMA regulates spindle orientation in the C. elegans germ line.

Mitotic spindle orientation contributes to tissue organization and shape by setting the cell division plane. How spindle orientation is coupled to diverse tissue architectures is incompletely understood. The C. elegans gonad is a tube-shaped organ with germ cells forming a circumferential monolayer around a common cytoplasmic lumen. How this organization is maintained during development is unclear, as germ cells lack the canonical cell-cell junctions that ensure spindle orientation in other tissue types. Here, we show that the microtubule force generator dynein and its conserved regulator LIN-5/NuMA regulate germ cell spindle orientation and are required for germline tissue organization. We uncover a cyclic, polarized pattern of LIN-5/NuMA cortical localization that predicts centrosome positioning throughout the cell cycle, providing a means to align spindle orientation with the tissue plane. This work reveals a new mechanism by which oriented cell division can be achieved to maintain tissue organization during animal development.