Abstract
Mitotic spindle positioning by cortical pulling forces defines the cell division axis and location, which is critical for proper cell division and development. Although recent work has identified developmental and extrinsic cues that regulate spindle orientation, the contribution of intrinsic signals to spindle positioning and orientation remains unclear. Here, we demonstrate that cortical force generation in human cells is controlled by distinct spindle-pole- and chromosome-derived signals that regulate cytoplasmic dynein localization. First, dynein exhibits a dynamic asymmetric cortical localization that is negatively regulated by spindle-pole proximity, resulting in spindle oscillations to centre the spindle within the cell. We find that this signal comprises the spindle-pole-localized polo-like kinase (Plk1), which regulates dynein localization by controlling the interaction between dynein-dynactin and its upstream cortical targeting factors NuMA and LGN. Second, a chromosome-derived RanGTP gradient restricts the localization of NuMA-LGN to the lateral cell cortex to define and maintain the spindle orientation axis. RanGTP acts in part through the nuclear localization sequence of NuMA to locally alter the ability of NuMA-LGN to associate with the cell cortex in the vicinity of chromosomes. We propose that these chromosome- and spindle-pole-derived gradients generate an intrinsic code to control spindle position and orientation.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Antigens, Nuclear / genetics
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Antigens, Nuclear / metabolism
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Blotting, Western
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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Centrioles / metabolism
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Centrioles / physiology
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Chromosome Segregation / physiology*
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Cytoplasmic Dyneins / genetics
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Cytoplasmic Dyneins / metabolism
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Dynactin Complex
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Dyneins / genetics
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Dyneins / metabolism
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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HeLa Cells
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Humans
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism
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Mice
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Microscopy, Fluorescence
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism
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Mitosis / physiology*
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Models, Biological
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Molecular Sequence Data
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NIH 3T3 Cells
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Nuclear Matrix-Associated Proteins / genetics
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Nuclear Matrix-Associated Proteins / metabolism
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Polo-Like Kinase 1
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Protein Binding
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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RNA Interference
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Signal Transduction / physiology*
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Spindle Apparatus / metabolism
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Spindle Apparatus / physiology*
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ran GTP-Binding Protein / genetics
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ran GTP-Binding Protein / metabolism
Substances
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Antigens, Nuclear
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Cell Cycle Proteins
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Dynactin Complex
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GPSM2 protein, human
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Intracellular Signaling Peptides and Proteins
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Microtubule-Associated Proteins
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NUMA1 protein, human
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Nuclear Matrix-Associated Proteins
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Proto-Oncogene Proteins
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Green Fluorescent Proteins
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Protein Serine-Threonine Kinases
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Cytoplasmic Dyneins
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Dyneins
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ran GTP-Binding Protein