Centriolar satellite protein CCDC66 interacts with CEP290 and functions in cilium formation and trafficking

Abstract

Centriolar satellites are membrane-less structures that localize and move around the centrosome/cilium complex in a microtubule-dependent manner. They play important roles in centrosome/cilium-related processes including protein trafficking to the centrosome/cilium complex and ciliogenesis, and are implicated in ciliopathies. Despite the important regulatory roles of centriolar satellites in the assembly and function of the centrosome/cilium complex, the molecular mechanism of their functions remains poorly understood. To dissect the mechanism of their regulatory roles during ciliogenesis, we determined the proteins proximate to the satellite protein CEP72, among which is the retinal degeneration gene product CCDC66. We identified CCDC66 as a microtubule-associated protein that dynamically localizes to the centrosome, centriolar satellites and the primary cilium throughout the cell cycle. Like the BBSome component BBS4, CCDC66 distributes between satellites and the primary cilium during ciliogenesis. CCDC66 has extensive proximity interactions with centrosome and centriolar satellite proteins and co-immunoprecipitation experiments revealed interactions between CCDC66, CEP290 and PCM1. Ciliogenesis, ciliary recruitment of BBS4 and centriolar satellite organization are impaired in cells depleted for CCDC66. Together, our findings identify CCDC66 as a targeting factor for centrosome/cilium proteins.