No centriole, no centrosome

Abstract

The centriole is a cylinder of nine triplet microtubules found at the core of the centrosome. The location of centrioles within the centrosome has always seemed to suggest a role in centrosome function, but proof of this has remained elusive. In part, this is due to the lack of convenient methods to remove centrioles specifically. For example, microsurgery or laser ablation will remove or damage not just the centriole but the entire centrosome as well.Bobinnec et al.1xCentriole disassembly in vivo and its effect on centrosome structure and function in vertebrate cells. Bobinnec, Y., Khodjakov, A., Mir, L.M., Rieder, C.L., Edde, B., and Bornens, M. J. Cell Biol. 1998; 143: 1575–1589CrossRef | PubMed | Scopus (234)See all References1 have come up with an elegant way to test the role of centrioles in centrosome function, using antibodies to polyglutamylated tubulin, a tubulin isoform that, in HeLa cells, is found only in the centriole. Bobinnec et al. introduced monoclonal antibodies to polyglutamylated tubulin into HeLa cells by both microinjection and electroporation, and the effect was dramatic. Centrioles disappeared completely from antibody-treated cells.Remarkably, when centrioles disappeared, centrosomes were no longer detectable either. No microtubule-organizing centres remained, and the pericentriolar material (e.g. γ-tubulin) became dispersed throughout the cytoplasm. Because presumably the antibodies acted directly on centrioles, this result implies that centrioles are necessary to maintain centrosome organization. As the antibodies degraded, centrioles reappeared, and, as soon as they did, functional centrosomes reassembled around them, suggesting that centrioles are sufficient to direct the assembly of a centrosome. This study breathes new life into the old idea that centrioles are important for centrosome function and ought to spark a fresh round of inquiry into these mysterious little organelles.