Chromosome- and spindle-pole-derived signals generate an intrinsic code for spindle position and ori

Abstract

Spindle orientation depends on the tethering of microtubules to the cell cortex through LGN, NuMA and dynein/dynactin. Cheeseman and colleagues find that spindle-pole-associated Plk1 activity restricts polar dynein whereas chromosomal RanGTP negatively regulates LGN localization at the lateral cell cortex, thus identifying two differentially localized signals that modulate spindle positioning by acting on dynein-mediated forces. Mitotic spindle positioning by cortical pulling forces1 defines the cell division axis and location2, which is critical for proper cell division and development3. Although recent work has identified developmental and extrinsic cues that regulate spindle orientation4,5,6, 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.

Cite this article

Kiyomitsu, T., Cheeseman, I. Chromosome- and spindle-pole-derived signals generate an intrinsic code for spindle position and orientation. Nat Cell Biol 14, 311–317 (2012). https://doi.org/10.1038/ncb2440

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