title: APC and EB1 function together in mitosis to regulate spindle dynamics and chromosome alignment.
abstract: Recently, we have shown that a cancer causing truncation in adenomatous polyposis coli (APC) (APC(1-1450)) dominantly interferes with mitotic spindle function, suggesting APC regulates microtubule dynamics during mitosis. Here, we examine the possibility that APC mutants interfere with the function of EB1, a plus-end microtubule-binding protein that interacts with APC and is required for normal microtubule dynamics. We show that siRNA-mediated inhibition of APC, EB1, or APC and EB1 together give rise to similar defects in mitotic spindles and chromosome alignment without arresting cells in mitosis; in contrast inhibition of CLIP170 or LIS1 cause distinct spindle defects and mitotic arrest. We show that APC(1-1450) acts as a dominant negative by forming a hetero-oligomer with the full-length APC and preventing it from interacting with EB1, which is consistent with a functional relationship between APC and EB1. Live-imaging of mitotic cells expressing EB1-GFP demonstrates that APC(1-1450) compromises the dynamics of EB1-comets, increasing the frequency of EB1-GFP pausing. Together these data provide novel insight into how APC may regulate mitotic spindle function and how errors in chromosome segregation are tolerated in tumor cells.
authors: Section of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA.
authors: Rebecca A
authors: RA
authors: Green
authors: Roy
authors: R
authors: Wollman
authors: Kenneth B
authors: KB
authors: Kaplan
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000502:physiology*; D045584:Chromosome Positioning / Q000502:physiology*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D008941:Spindle Apparatus / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D025601:Adenomatous Polyposis Coli Protein; C500985:MAPRE1 protein, human; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; C076744:cytoplasmic linker protein 170; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; C084102:PAFAH1B1 protein, human