title: An Asp-CaM complex is required for centrosome-pole cohesion and centrosome inheritance in neural stem cells.
abstract: The interaction between centrosomes and mitotic spindle poles is important for efficient spindle formation, orientation, and cell polarity. However, our understanding of the dynamics of this relationship and implications for tissue homeostasis remains poorly understood. Here we report that Drosophila melanogaster calmodulin (CaM) regulates the ability of the microcephaly-associated protein, abnormal spindle (Asp), to cross-link spindle microtubules. Both proteins colocalize on spindles and move toward spindle poles, suggesting that they form a complex. Our binding and structure-function analysis support this hypothesis. Disruption of the Asp-CaM interaction alone leads to unfocused spindle poles and centrosome detachment. This behavior leads to randomly inherited centrosomes after neuroblast division. We further show that spindle polarity is maintained in neuroblasts despite centrosome detachment, with the poles remaining stably associated with the cell cortex. Finally, we provide evidence that CaM is required for Asp's spindle function; however, it is completely dispensable for Asp's role in microcephaly suppression.
authors.affiliation: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Todd
authors.initials: T
authors.lastname: Schoborg
authors.affiliation: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Allison L
authors.initials: AL
authors.lastname: Zajac
authors.affiliation: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Carey J
authors.initials: CJ
authors.lastname: Fagerstrom
authors.affiliation: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Rodrigo X
authors.initials: RX
authors.lastname: Guillen
authors.affiliation: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892 Nasser@nih.gov.
authors.forename: Nasser M
authors.initials: NM
authors.lastname: Rusan
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology; D002147:Calmodulin / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D016764:Cell Polarity; D018385:Centrosome / Q000378:metabolism*; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism; D005091:Exons; D005838:Genotype; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D058953:Neural Stem Cells / Q000166:cytology*; D010641:Phenotype; D011485:Protein Binding; D034622:RNA Interference; D008941:Spindle Apparatus / Q000378:metabolism
chemical_list: D002147:Calmodulin; D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; C106174:asp protein, Drosophila; D049452:Green Fluorescent Proteins