Extra centrosomes and/or chromosomes prolong mitosis in human cells - PubMed (original) (raw)

Extra centrosomes and/or chromosomes prolong mitosis in human cells

Zhenye Yang et al. Nat Cell Biol. 2008 Jun.

Abstract

Using laser microsurgery and cell fusion we have explored how additional centrosomes and/or chromosomes influence the duration of mitosis in human cells. We found that doubling the chromosome number added approximately 10 min to a 20 min division, whereas doubling the number of centrosomes added approximately 30 min more. Extra centrosomes and/or chromosomes prolong mitosis by delaying satisfaction of the spindle assembly checkpoint. Thus mitosis can be prolonged by non-genetic means and extra chromosomes and centrosomes probably contribute to the elevated mitotic index seen in many tumours.

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Figures

Figure 1

Figure 1

Doubling the chromosome number in human RPE-1 cells prolongs mitosis by delaying satisfaction of the spindle assembly checkpoint. (a) The duration of mitosis in binucleated (4N) RPE-1 cells expressing human centrin-1/GFP (a centriolar tag) averaged 49 ± 17 minutes, compared to 20 ± 3 minutes in neighboring mononucleated (2N) controls, and binucleated cells initially formed tetrapolar spindles that reorganize into bipolar or tripolar spindles before anaphase. (b) Injecting binucleated cells shortly after nuclear envelope breakdown (7’) with purified Mad2-ΔC induces anaphase (25’) within 17∼22 min. (c) Destroying one centrosome in a binucleated G1 cell by laser microsurgery produces cells that form normal bipolar spindles that average 33 ± 5 minutes in mitosis. (d) The 4N mononucleated G1 cells produced from the division in (c) contained a single centrosome, and averaged 29±5 min in the next mitosis. The fluorescence images in (c) and (d) were acquired in G1 and scale bars = 2 μm. Scale bars = 10 μm in (a) and 20 μm in the phase images (b, c, d).

Figure 2

Figure 2

Extra centrosomes prolong mitosis in mononucleated (2N) cells. (a) Enucleated G1 RPE-1 cytoplasts containing one centrin-1/GFP labeled centrosome were electrofused with surrounding G1 cells. (b) This produced G1 cells containing a 2N nucleus and 2 centrosomes, which subsequently replicated into a 4N nucleus and 4 centrosomes. (c) As this cell entered mitosis it formed a tetrapolar spindle (16’) that became bipolar (26’, 64’) so that the chromosomes were segregated into two cells. In this example the duration of mitosis was 64 minutes (the average from 11 cells was 53 ± 21 minutes). Time is in minutes. Scale bars = 10 μm.

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