The centriole is a ninefold symmetrical structure found at the core of centrosomes and, as a basal body, at the base of cilia, whose conserved duplication is regulated by Plk4 kinase. Plk4 phosphorylates a single serine residue at the N-terminus of Ana2 to promote Ana2's loading to the site of procentriole formation. Four conserved serines in Ana2's STAN motif are then phosphorylated by Plk4, enabling Sas6 recruitment.
View Article and Find Full Text PDFWe demonstrate that a Drosophila Golgi protein, Gorab, is present not only in the trans-Golgi but also in the centriole cartwheel where, complexed to Sas6, it is required for centriole duplication. In addition to centriole defects, flies lacking Gorab are uncoordinated due to defects in sensory cilia, which lose their nine-fold symmetry. We demonstrate the separation of centriole and Golgi functions of Drosophila Gorab in two ways: first, we have created Gorab variants that are unable to localize to trans-Golgi but can still rescue the centriole and cilia defects of gorab null flies; second, we show that expression of C-terminally tagged Gorab disrupts Golgi functions in cytokinesis of male meiosis, a dominant phenotype overcome by mutations preventing Golgi targeting.
View Article and Find Full Text PDFThe conserved process of centriole duplication requires Plk4 kinase to recruit and promote interactions between Sas6 and Sas5/Ana2/STIL (respective nomenclature of worms/flies/humans). Plk4-mediated phosphorylation of Ana2/STIL in its conserved STAN motif has been shown to promote its interaction with Sas6. However, STAN motif phosphorylation is not required for recruitment of Ana2 to the centriole.
View Article and Find Full Text PDFCentrioles are required to assemble centrosomes for cell division and cilia for motility and signalling. New centrioles assemble perpendicularly to pre-existing ones in G1-S and elongate throughout S and G2. Fully elongated daughter centrioles are converted into centrosomes during mitosis to be able to duplicate and organize pericentriolar material in the next cell cycle.
View Article and Find Full Text PDFAxons act like cables, electrically wiring the nervous system. Polar bundles of microtubules (MTs) form their backbones and drive their growth. Plus end-tracking proteins (+TIPs) regulate MT growth dynamics and directionality at their plus ends.
View Article and Find Full Text PDFCentrioles are 9-fold symmetrical structures at the core of centrosomes and base of cilia whose dysfunction has been linked to a wide range of inherited diseases and cancer. Their duplication is regulated by a protein kinase of conserved structure, the C. elegans ZYG-1 or its Polo-like kinase 4 (Plk4) counterpart in other organisms.
View Article and Find Full Text PDFLittle is known about how microtubules are regulated in different cell types during development. EB1 plays a central role in the regulation of microtubule plus ends. It directly binds to microtubule plus ends and recruits proteins which regulate microtubule dynamics and behaviour.
View Article and Find Full Text PDFThe ability to identify protein interactions is key to elucidating the molecular mechanisms of cellular processes, including mitosis and cell cycle regulation. Drosophila melanogaster, as a model system, provides powerful tools to study cell division using genetics, microscopy, and RNAi. Drosophila early embryos are highly enriched in mitotic protein complexes as their nuclei undergo 13 rounds of rapid, synchronous mitotic nuclear divisions in a syncytium during the first 2 h of development.
View Article and Find Full Text PDFMicrotubule-based transport mediates the sorting and dispersal of many cellular components and pathogens. However, the mechanisms by which motor complexes are recruited to and regulated on different cargos remain poorly understood. Here we describe a large-scale biochemical screen for novel factors associated with RNA localization signals mediating minus end-directed mRNA transport during Drosophila development.
View Article and Find Full Text PDFMicrotubule plus ends are dynamic ends that interact with other cellular structures. Microtubule plus end tracking proteins are considered to play important roles in the regulation of microtubule plus ends. Recent studies revealed that EB1 is the central regulator for microtubule plus end tracking proteins by recruiting them to microtubule plus ends through direct interaction.
View Article and Find Full Text PDFCentrioles are found in the centrosome core and, as basal bodies, at the base of cilia and flagella. Centriole assembly and duplication is controlled by Polo-like-kinase 4 (Plk4): these processes fail if Plk4 is downregulated and are promoted by Plk4 overexpression. Here we show that the centriolar protein Asterless (Asl; human orthologue CEP152) provides a conserved molecular platform, the amino terminus of which interacts with the cryptic Polo box of Plk4 whereas the carboxy terminus interacts with the centriolar protein Sas-4 (CPAP in humans).
View Article and Find Full Text PDFConventional centrosomes are absent from a female meiotic spindle in many animals. Instead, chromosomes drive spindle assembly, but the molecular mechanism of this acentrosomal spindle formation is not well understood. We have screened female sterile mutations for defects in acentrosomal spindle formation in Drosophila female meiosis.
View Article and Find Full Text PDFCLIP-170 was the first microtubule plus-end-tracking protein to be described, and is implicated in the regulation of microtubule plus-ends and their interaction with other cellular structures. Here, we have studied the cell-cycle-dependent mechanisms which localise the sole Drosophila melanogaster homologue CLIP-190. During mitosis, CLIP-190 localises to unattached kinetochores independently of spindle-checkpoint activation.
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