Individual cilia in multiciliated cells display coordinated beating, which generates anterior–posterior flow and is essential for normal development. The cytoskeleton has been implicated in ciliogenesis and in cilia orientation, but its precise role in ciliary organization has not been fully elucidated. Mitchell and colleagues now reveal how actin and microtubules coordinately regulate this process (J. Cell Biol. 195, 19–26; 2011).

The authors identified a previously unrecognized pool of actin that connects neighbouring cilia. Disrupting this actin framework blocked coordinated ciliary polarity and caused irregular basal body spacing. Intriguingly, clusters of neighbouring cilia were still able to orient together, suggesting that actin is only required for long-distance coordination. However, blocking microtubule function with nocadazole inhibited even the local coordination of cilia. Thus, actin and microtubules are both required for ciliary organization but have discrete roles.

In addition to orientation, ciliary beating must also be coordinated to generate flow. This process, called metachronal synchrony, was also dependent on the actin network. Together, these results suggest that the cytoskeleton is essential for coordination of ciliary organization and beating, and raise the possibility that mechanical force is transmitted through cytoskeletal links to synchronize these processes.