1. Departments of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
2. Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
3. Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, New York 10021, USA
4. Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
5. These authors contributed equally to this work.

Correspondence to: Michael A. Lampson^2,5P. Todd Stukenberg¹ Correspondence and requests for materials should be addressed to P.T.S. (Email: pts7h@virginia.edu) or M.A.L. (Email: lampson@sas.upenn.edu).

Abstract

Proper partitioning of the contents of a cell between two daughters requires integration of spatial and temporal cues. The anaphase array of microtubules that self-organize at the spindle midzone contributes to positioning the cell-division plane midway between the segregating chromosomes¹. How this signalling occurs over length scales of micrometres, from the midzone to the cell cortex, is not known. Here we examine the anaphase dynamics of protein phosphorylation by aurora B kinase, a key mitotic regulator, using fluorescence resonance energy transfer (FRET)-based sensors in living HeLa cells and immunofluorescence of native aurora B substrates. Quantitative analysis of phosphorylation dynamics, using chromosome- and centromere-targeted sensors, reveals that changes are due primarily to position along the division axis rather than time. These dynamics result in the formation of a spatial phosphorylation gradient early in anaphase that is centred at the spindle midzone. This gradient depends on aurora B targeting to a subpopulation of microtubules that activate it. Aurora kinase activity organizes the targeted microtubules to generate a structure-based feedback loop. We propose that feedback between aurora B kinase activation and midzone microtubules generates a gradient of post-translational marks that provides spatial information for events in anaphase and cytokinesis.

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