title: The role of NEDD1 phosphorylation by Aurora A in chromosomal microtubule nucleation and spindle function.
abstract: Chromatin directs de novo microtubule (MT) nucleation in dividing cells by generating a gradient of GTP-bound Ran protein (RanGTP) that controls the activity of a number of spindle assembly factors (SAFs). It is now well established that these MTs are essential for the assembly of a functional bipolar spindle. Although it has been shown that RanGTP-dependent MT nucleation requires γ-tubulin and a number of RanGTP-regulated proteins, the mechanism involved is still poorly understood. We previously showed that the mitotic kinase Aurora A, which is activated in a RanGTP-dependent manner in mitotic cells, has a role in this pathway. Here we show that Aurora A interacts with and phosphorylates the γTURC adaptor protein NEDD1 at a single residue, Ser405. Ser405 phosphorylation is not required for centrosomal MT nucleation but is critical for MT nucleation in the vicinity of the chromosomes in mitotic cells. Moreover, it is essential for RanGTP aster formation and chromatin-driven MT assembly in Xenopus egg extracts. Our data suggest that one important function of Aurora A in mitotic cells is to promote MT nucleation around the chromatin by phosphorylating NEDD1, and thereby to promote functional spindle assembly.
authors.affiliation: Centre for Genomic Regulation, Doctor Aiguader 88, 08003 Barcelona, Spain.
authors.forename: Roser
authors.initials: R
authors.lastname: Pinyol
authors.forename: Jacopo
authors.initials: J
authors.lastname: Scrofani
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vernos
mesh_terms: D000818:Animals; D064127:Aurora Kinases; D002875:Chromosomes / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D059566:M Phase Cell Cycle Checkpoints; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000378:metabolism
chemical_list: D008869:Microtubule-Associated Proteins; C529826:NEDD1 protein, Xenopus; C509189:NEDD1 protein, human; D029867:Xenopus Proteins; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D020931:ran GTP-Binding Protein