Article

Building the Centriole

Department of Biochemistry and Biophysics, University of California, San Francisco, 94143, USA.
Current biology: CB (Impact Factor: 9.57). 09/2010; 20(18):R816-25. DOI: 10.1016/j.cub.2010.08.010
Source: PubMed

ABSTRACT

Centrioles are conserved microtubule-based organelles that lie at the core of the animal centrosome and play a crucial role in nucleating the formation of cilia and flagella in most eukaryotes. Centrioles have a complex ultrastructure with ninefold symmetry and a well-defined length. This structure is assembled from a host of proteins, including a variety of disease gene products. Over a century after the discovery of centrioles, the mechanisms underlying the assembly of these fascinating organelles, in particular the establishment of ninefold symmetry and the control of centriole length, are now starting to be uncovered.

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Available from: Juliette Azimzadeh, Apr 15, 2014
    • "It is beyond the scope of this chapter to introduce even a subset of the bona fide components of centrioles or centrosomes , let alone discuss their discovery, potential functions, and hierarchy of assembly. Several excellent reviews exist, which detail the identity, function , and mode of discovery for many centriole proteins (Bornens, 2002; Nigg, 2007; Strnad and Gönczy, 2008; Bettencourt-Dias and Glover, 2007; Azimzadeh and Marshall, 2010; Nigg and Stearns, 2011; Brito et al., 2012; Gönczy, 2012; Avidor-Reiss and Gopalakrishnan, 2013). "
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    ABSTRACT: The assembly of a bipolar spindle lies at the heart of mitotic chromosome segregation. In animal somatic cells, the process of spindle assembly involves multiple complex interactions between various cellular compartments, including an emerging antiparallel microtubule network, microtubule-associated motor proteins and spindle assembly factors, the cell's cortex, and the chromosomes themselves. The result is a dynamic structure capable of aligning pairs of sister chromatids, sensing chromosome misalignment, and generating force to segregate the replicated genome into two daughters. Because the centrosome lies at the center of the array of microtubule minus-ends, and the essential one-to-two duplication of the centrosome prior to mitosis is linked to cell cycle progression, this organelle has long been implicated as a device to generate spindle bipolarity. However, this classic model for spindle assembly is challenged by observations and experimental manipulations demonstrating that acentrosomal cells can and do form bipolar spindles, both mitotic and meiotic. Indeed, recent comprehensive proteomic analysis of centrosome-dependent versus independent mitotic spindle assembly mechanisms reveals a large, common set of genes required for both processes, with very few genes needed to differentiate between the two. While these studies cast doubt on an absolute role for the centrosome in establishing spindle polarity, it is clear that having too few or too many centrosomes results in abnormal chromosome segregation and aneuploidy. Here we review the case both for and against the role of the centrioles and centrosomes in ensuring proper assembly of a bipolar spindle, an essential element in the maintenance of genomic stability.
    No preview · Article · Nov 2014 · International review of cell and molecular biology
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    • "In the past decade, a cohort of centrosome components was identified and the role of these proteins characterized in model organisms. In particular, pioneering studies in C. elegans and Drosophila uncovered a set of structural components and regulators of centriole assembly, many of which are conserved across ciliated eukaryotes[9,23,24,113,114]. The ability to isolate centrosomes also allowed the identification of additional centrosome components by proteomic approaches in animals, budding yeast and Dictyostelium115116117118. Most of the core components of the human centrosome have orthologues in the genome of the planarian Schmidtea mediterranea, which completely lacks centrosomes but forms centrioles de novo in ciliated cell types. "
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    ABSTRACT: The centrosome is the main organizer of the microtubule cytoskeleton in animals, higher fungi and several other eukaryotic lineages. Centrosomes are usually located at the centre of cell in tight association with the nuclear envelope and duplicate at each cell cycle. Despite a great structural diversity between the different types of centrosomes, they are functionally equivalent and share at least some of their molecular components. In this paper, we explore the evolutionary origin of the different centrosomes, in an attempt to understand whether they are derived from an ancestral centrosome or evolved independently from the motile apparatus of distinct flagellated ancestors. We then discuss the evolution of centrosome structure and function within the animal lineage.
    Preview · Article · Sep 2014 · Philosophical Transactions of The Royal Society B Biological Sciences
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    • "For the establishment of the ninefold symmetrical centriole structure, the length of the cartwheel spoke is as important as the assembly of the ninefold symmetrical hub [53,54]. Experiments using Chlamydomonas bld10 mutants expressing truncated Bld10p revealed that Bld10p constitutes the distal part of the spoke and contributes to the formation of spokes of the proper length (figure 5b) [26]. "
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    ABSTRACT: The cartwheel is a subcentriolar structure consisting of a central hub and nine radially arranged spokes, located at the proximal end of the centriole. It appears at the initial stage of the centriole assembly process as the first ninefold symmetrical structure. The cartwheel was first described more than 50 years ago, but it is only recently that its pivotal role in establishing the ninefold symmetry of the centriole was demonstrated. Significant progress has since been made in understanding its fine structure and assembly mechanism. Most importantly, the central part of the cartwheel, from which the ninefold symmetry originates, is shown to form by self-association of nine dimers of the protein SAS-6. This finding, together with emerging data on other components of the cartwheel, has opened new avenues in centrosome biology.
    Full-text · Article · Sep 2014 · Philosophical Transactions of The Royal Society B Biological Sciences
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