DEUP1 functions as a scaffold for basal foot integrity and planar polarity in multiciliated cells

Multiciliated cells generate numerous centrioles to support motile cilia essential for fluid flow. This process was thought to rely on the deuterosome, a DEUP1-dependent structure. Here, we show that DEUP1 plays a critical role in the basal foot (BF)-an asymmetric appendage of the basal body required for coordinated ciliary beating. Using high-resolution imaging, we localize DEUP1 to the middle tier of the BF, adjacent to CNTRL. In DEUP1 knockout mice, BF architecture is disrupted, leading to loss of rotational planar polarity, reduced cerebrospinal fluid flow, and ciliary degeneration with age. These defects are recapitulated in Xenopus epidermis, demonstrating evolutionary conservation. Notably, DEUP1 loss alone does not affect basal body or cilia number during early or mature adult stages, with overt degeneration emerging only in aged animals. Together, these findings establish DEUP1 as a key structural regulator of BF integrity that is required for the long-term maintenance of coordinated ciliary motility.