title: Drosophila Ajuba is not an Aurora-A activator but is required to maintain Aurora-A at the centrosome.
abstract: The LIM-domain protein Ajuba localizes at sites of epithelial cell-cell adhesion and has also been implicated in the activation of Aurora-A (Aur-A). Despite the expected importance of Ajuba, Ajuba-deficient mice are viable, which has been attributed to functional redundancy with the related LIM-domain protein LIMD1. To gain insights into the function of Ajuba, we investigated its role in Drosophila, where a single gene (jub) encodes a protein closely related to Ajuba and LIMD1. We identified a key function in neural stem cells, where Jub localizes to the centrosome. In these cells, mutation in jub leads to centrosome separation defects and aberrant mitotic spindles, which is a phenotype similar to that of aur-A mutants. We show that in jub mutants Aur-A activity is not perturbed, but that Aur-A recruitment and maintenance at the centrosome is affected. As a consequence the active kinase is displaced from the centrosome. On the basis of our studies in Drosophila neuroblasts, we propose that a key function of Ajuba, in these cells, is to maintain active Aur-A at the centrosome during mitosis.
authors.affiliation: Compartimentation et Dynamique Cellulaires, CNRS, UMR144 Paris F-75248, France.
authors.forename: Dora
authors.initials: D
authors.lastname: Sabino
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Brown
authors.forename: Renata
authors.initials: R
authors.lastname: Basto
mesh_terms: D000818:Animals; D064096:Aurora Kinase A; D064127:Aurora Kinases; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018385:Centrosome / Q000201:enzymology / Q000378:metabolism*; D004330:Drosophila / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000378:metabolism*; D060588:LIM Domain Proteins; D008938:Mitosis; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D029721:Drosophila Proteins; D020536:Enzyme Activators; D060588:LIM Domain Proteins; C559477:jub protein, Drosophila; C576918:Aurka protein, mouse; D064096:Aurora Kinase A; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases