Centriolar cap in action

Centriolar cap proteins CP110 and CPAP control slow elongation of microtubule plus ends.

Iyer SS, Chen F, Ogunmolu FE, Moradi S, Volkov VA, van Grinsven EJ, van Hoorn C, Wu J, Andrea N, Hua S, Jiang K, Vakonakis I, Potočnjak M, Herzog F, Gigant B, Gudimchuk N, Stecker KE, Dogterom M, Steinmetz MO, Akhmanova A.
J Cell Biol. 2025 Mar 3;224(3):e202406061. doi: 10.1083/jcb.202406061.
PMID: 39847124

Centrioles are symmetric microtubule-based structures that are needed to form centrosomes and cilia. Unlike other microtubules in cells, centriolar microtubules are extremely stable and grow extremely slowly, but the reasons for this are poorly understood. In this study, the Akhmanova lab in collaboration with researchers from Delft University, Paul Scherrer Institute in Switzerland and several other European countries has reconstituted the workings of the cap that controls centriole growth. They discovered that one of the cap proteins, CP110, attaches to the ends of microtubules, stopping them from growing or shrinking, while another protein, CPAP, promotes microtubule growth by overcoming CP110’s blocking effect. Using Electron Microscopy, they found that CP110 binds to the inside of microtubule ends, keeping them stable.  Together, CP110 and CPAP cause the very slow and steady microtubule growth needed for centriole formation. If their interaction is disrupted, centrioles cannot grow properly, leading to defects. This work provides insight into the formation of an ancient and beautiful cellular structure.