The inner scaffold protects from centriole fracture

Abstract Centrioles are characterized by a nine-fold arrangement of microtubule triplets held together by an inner protein scaffold. While performing their functions, these organelles experience strenuous cellular forces without breaking. What maintains centriole integrity is a fundamental question that remains poorly understood. Here, we reveal the function of the inner scaffold in imparting centriole cohesion by studying POC16 and its human homolog WDR90. We unveil POC16/WDR90, as microtubule-binding proteins that localize on the microtubule wall along the central core region of the centriole and interact with the inner scaffold components FAM161A and POC5. Strikingly, WDR90/POC16 depletion impairs the inner scaffold, leading to structural abnormalities and centriole fracture in human and Chlamydomonas cells. This work highlights the importance of the inner scaffold in protecting centriole architecture. One Sentence Summary Centriole integrity is ensured by the connection between the inner scaffold and microtubule triplets through POC16/WDR90 proteins.