During cell division, mitotic spindles are assembled by microtubule-based motor proteins.
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One or two sentences providing a basic introduction to the field, comprehensible to a scientist in any discipline.
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The bipolar organization of spindles is essential for proper segregation of chromosomes and requires plus-end-directed homotetrameric motor proteins of the widely conserved kinesin-5 (BimC) family. Hypotheses for bipolar spindle formation include the 'push-pull mitotic muscle' model, in which kinesin-5 and opposing motor proteins act between overlapping microtubules.
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Two or three sentences of more detailed background, comprehensible to scientists in related disciplines.
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However, the precise roles of kinesin-5 during this process are unknown.
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One sentence clearly stating the general problem being addressed by this particular study.
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Here we show that the vertebrate kinesin-5 Eg5 drives the sliding of microtubules depending on their relative orientation.
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One sentence summarizing the main result (with the words "here we show" or their equivalent).
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We found in controlled in vitro assays that Eg5 has the remarkable capability of simultaneously moving at ~20 nm s-1 towards the plus-ends of eac of the two microtubules if crosslinks. For anti-parallel microtubules, this results in relative sliding at ~40 nm s-1, comparable to spindle pole separation rates in vitro. Furthermore, we found that Eg5 can tether microtubule plus-ends, suggesting an additional microtubule-binding mode for Eg5.
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Two or three sentences explaining what the main result reveals in direct comparison to what was thought to be the case previously, or how the main result adds to previous knowledge.
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Our results demonstrate how members of the kinesin-5 family are likely to function in mitosis, pushing apart interpolar microtubules as well as recruiting microtubules into bundles that are sequentially polarized by relative sliding.
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One or two sentences to put the results into a more general context.
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We anticipate our assay to be a starting point for more sophisticated in vitro models of mitotic spindles. For example, the individual and combined action of multiple mitotic motors could be tested, including minus-end-directed motors opposing Eg5 motility. Furthermore, Eg5 inhibition is a major target of anti-cancer drug development, and a well-defined and quantitative assay for motor function will be relevant for such developments.
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Two or three sentences to provide a broader perspective, readily comprehensible to a scientist in any discipline, may be included in the first paragraph if the editor considers that the accessibility of the paper is significantly enhanced by their inclusion. Under these circumstances, the length of the paragraph can be up to 300 words.
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