Abstract

Centrioles are highly elaborate microtubule-based structures responsible for the formation of centrosomes and cilia. Despite considerable variation across species and tissues within any given tissue, their size is essentially constant [1, 2]. While the diameter of the centriole cylinder is set by the dimensions of the inner scaffolding structure of the cartwheel [3], how centriole length is set so precisely and stably maintained over many cell divisions is not well understood. Cep97 and CP110 are conserved proteins that localize to the distal end of centrioles and have been reported to limit centriole elongation in vertebrates [4, 5]. Here, we examine Cep97 function in Drosophila melanogaster. We show that Cep97 is essential for formation of full-length centrioles in multiple tissues of the fly. We further identify the microtubule deacetylase Sirt2 as a Cep97 interactor. Deletion of Sirt2 likewise affects centriole size. Interestingly, so does deletion of the acetylase Atat1, indicating that loss of stabilizing acetyl marks impairs centriole integrity. Cep97 and CP110 were originally identified as inhibitors of cilia formation in vertebrate cultured cells [6], and loss of CP110 is a widely used marker of basal body maturation. In contrast, in Drosophila, Cep97 appears to be only transiently removed from basal bodies and loss of Cep97 strongly impairs ciliogenesis. Collectively, our results support a model whereby Cep97 functions as part of a protective cap that acts together with the microtubule acetylation machinery to maintain centriole stability, essential for proper function in cilium biogenesis.

Highlights

  • 0A results in a dramatic extension of centriole size, an effect suppressed by overexpression of CP110 [16, 17]

  • PLK4/Sak/ZYG-1 is recruited to the mother centriole, where it concentrates into a single focus that marks the site of daughter centriole assembly

  • Overexpression of CPAP as well as its interacting proteins CEP120 and SPICE1 results in over-elongation of centrioles [4, 5, 8,9,10], and recent studies demonstrate that CPAP imparts slow, processive growth on centriolar microtubules [11, 12]

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Summary

Introduction

0A results in a dramatic extension of centriole size, an effect suppressed by overexpression of CP110 [16, 17]. Loss of CP110 in the fly has only minor effects on centriole elongation and, results in shortening of centrioles in Dmel cells, hinting at context-dependent differences [16, 17]. While Cep and CP110 are thought to function together, it has been noted that hypomorphic Cep mutants display stronger phenotypes than CP110-null mutants, suggesting a role for Cep independent of CP110 [18]. We sought to carry out a comprehensive analysis of Cep in the fly, using newly developed tools to monitor protein localization and functio

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