CEP44 ensures the formation of bona fide centriole wall, a requirement for the centriole-to-centrosome conversion

Enrico S Atorino,Charlotta Funaya,Shoji Hata,Elmar Schiebel,Annett Neuner

doi:10.1038/s41467-020-14767-2

Enrico S Atorino, Charlotta Funaya + Show 3 more

Open Access

https://doi.org/10.1038/s41467-020-14767-2

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Journal: Nature Communications	Publication Date: Feb 14, 2020
Citations: 29	License type: open-access

Affiliation: Heidelberg University, DKFZ-ZMBH Alliance

Abstract

Centrosomes are essential organelles with functions in microtubule organization that duplicate once per cell cycle. The first step of centrosome duplication is the daughter centriole formation followed by the pericentriolar material recruitment to this centriole. This maturation step was termed centriole-to-centrosome conversion. It was proposed that CEP295-dependent recruitment of pericentriolar proteins drives centriole conversion. Here we show, based on the analysis of proteins that promote centriole biogenesis, that the developing centriole structure helps drive centriole conversion. Depletion of the luminal centriole protein CEP44 that binds to the A-microtubules and interacts with POC1B affecting centriole structure and centriole conversion, despite CEP295 binding to centrioles. Impairment of POC1B, TUBE1 or TUBD1, which disturbs integrity of centriole microtubules, also prevents centriole-to-centrosome conversion. We propose that the CEP295, CEP44, POC1B, TUBE1 and TUBD1 centriole biogenesis pathway that functions in the centriole lumen and on the cytoplasmic side is essential for the centriole-to-centrosome conversion.

Highlights

Centrosomes are essential organelles with functions in microtubule organization that duplicate once per cell cycle
The clear stronger impact on γ-tubulin than on centrin[1] suggested that the pericentriolar matrix (PCM) recruitment defect arises before the centriole loss. We explored this possibility further at an earlier time point of CEP44 depletion (60 h) when the centriole loss in G1 was minimal (5.1 ± 1.6, Supplementary Fig. 1e, f). 60% of the cells still showed a strong defect in the recruitment of both PCM components γ-tubulin and PCNT, which corresponded in its magnitude with the CEP44 loss (Fig. 1d–f; Supplementary Fig. 1e–i)
Affinity purified antibodies rose against the protein showed that in G1 and S phase (EdU positive) cells, CEP44 localised to mother centriole (mC) whereas in G2 cells it appeared as 4 foci localising to all 4 centrin[1] signals, the two mCs and two daughter centriole (dC) (Fig. 1a)

Summary

Introduction

Centrosomes are essential organelles with functions in microtubule organization that duplicate once per cell cycle. The first step of centrosome duplication is the daughter centriole formation followed by the pericentriolar material recruitment to this centriole. The centrosome is the main microtubule-organising centre (MTOC) of higher eukaryotic cells[1,2] This organelle comprises a central cylindrical tubulin-based structure, the centriole[3], and a protein matrix that surrounds the centriole called the pericentriolar matrix (PCM)[4,5,6]. After centriole formation in S/G2 phase, the dC is converted into a centrosome by the step-wise recruitment of PCM proteins This process called centriole-to-centrosome conversion (CCC)[15,16] is essential for the new centrosome to gain MT nucleation activity and the ability to duplicate. Our analysis identifies CEP44 as a luminal centriolar protein that binds to A-MTs and the inner centriole protein

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