| Summary: | Centrioles organise centrosomes and cilia and these organelles have an important role in many cell processes. In flies, the centriole protein Ana1 is required for the assembly of functional centrosomes and cilia. It has recently been shown that Cep135/Bld10 initially recruits Ana1 to newly formed centrioles and Ana1 then recruits Asl/Cep152 to promote the conversion of these centrioles to centrosomes. Here we show that ana1 mutants lack detectable centrosomes in vivo, that Ana1 is irreversibly incorporated into centrioles during their assembly, and that Ana1 appears to play a more important part in maintaining Asl at centrioles rather than initially recruiting Asl to centrioles. Unexpectedly, we also find that Ana1 promotes centriole elongation in a dose-dependent manner: centrioles are shorter when Ana1 dosage is reduced and are longer when Ana1 is overexpressed. This latter function of Ana1 appears to be distinct from its role in centrosome and cilium function, as a GFP-Ana1 fusion lacking the N-terminal 639aa of the protein can support centrosome assembly and cilium function but cannot promote centriole over-elongation when overexpressed.
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