Cilia perform essential signalling functions during development and tissue homeostasis. Ciliary malfunction causes a variety of diseases, named ciliopathies. The key role that the mother centriole plays in cilia formation can be attributed to appendage proteins that associate exclusively with the mother centriole. The distal appendages form a platform that docks early ciliary vesicles and removes CP110/Cep97 inhibitory complexes from the mother centriole. Here, we analysed the role played by LRRC45 in appendage formation and ciliogenesis. We show that the core appendage proteins Cep83 and SCLT1 recruit LRRC45 to the mother centriole. Once there LRRC45 recruits FBF1. The association of LRRC45 with the basal body of primary and motile cilia in differentiated and stem cells reveals a broad function in ciliogenesis. In contrast to the appendage components Cep164 and Cep123, LRRC45 was neither essential for docking of early ciliary vesicles nor for removal of CP110. Rather, LRRC45 promotes cilia biogenesis in CP110-uncapped centrioles by organising centriolar satellites and promoting the docking of Rab8 GTPase-positive vesicles. We propose that, instead of acting solely as a platform to recruit early vesicles, centriole appendages form discrete scaffolds of cooperating proteins that execute specific functions that promote the initial steps of ciliogenesis.
