RNAi analysis reveals an unexpected role for topoisomerase II in chromosome arm congression to a metaphase plate
| Autor: | William C. Earnshaw, Sarah E. Goulding, Mar Carmena, Chih-Jui Chang |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Kinetochore
Spindle Apparatus Cell Biology Biology Molecular biology Chromatin Histones Mitotic chromosome condensation DNA Topoisomerases Type II Prophase Microscopy Fluorescence Centromere Animals Topoisomerase II Inhibitors Sister chromatids Drosophila Phosphorylation RNA Small Interfering Anaphase Kinetochores Mitosis Metaphase Cell Division |
| Zdroj: | Journal of Cell Science. 116:4715-4726 |
| ISSN: | 1477-9137 0021-9533 |
| DOI: | 10.1242/jcs.00797 |
| Popis: | DNA topoisomerase II (Topo II) is a major component of mitotic chromosomes and an important drug target in cancer chemotherapy, however, its role in chromosome structure and dynamics remains controversial. We have used RNAi to deplete Topo II in Drosophila S2 cells in order to carry out a detailed functional analysis of the role of the protein during mitosis. We find that Topo II is not required for the assembly of a functional kinetochore or the targeting of chromosomal passenger proteins, nonetheless, it is essential for anaphase sister chromatid separation. In response to a long-running controversy, we show that Topo II does have some role in mitotic chromatin condensation. Chromosomes formed in its absence have a 2.5-fold decrease in the level of chromatin compaction, and are morphologically abnormal. However, it is clear that the overall programme of mitotic chromosome condensation can proceed without Topo II. Surprisingly, in metaphase cells depleted of Topo II, one or more chromosome arms frequently stretch out from the metaphase plate to the vicinity of the spindle pole. This is not kinetochore-based movement, as the centromere of the affected chromosome is located on the plate. This observation raises the possibility that further unexpected functions for Topo II may remain to be discovered. |
| Databáze: | OpenAIRE |
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