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- Title
The SUMO pathway is required for selective degradation of DNA topoisomerase IIβ induced by a catalytic inhibitor ICRF-193<sup>1</sup><FN ID="FN1"><NO>1</NO>The DT40 cell line used here (Ubc9<sup>−/−/−</sup>tetUbc9) will be available from RIKEN Cell Bank (http://www.rtc.riken.go.jp/CELL/HTML/RIKEN_Cell_Bank.html) by specifying the RCB number (RCB 1845) and the cell line name (delta Ubc9+cUbc9-DT40).</FN>
- Authors
Isik, Sevim; Sano, Kuniaki; Tsutsui, Kimiko; Seki, Masayuki; Enomoto, Takemi; Saitoh, Hisato; Tsutsui, Ken
- Abstract
DNA topoisomerase I and II have been shown to be modified with a ubiquitin-like protein SUMO in response to their specific inhibitors called ‘poisons’. These drugs also damage DNA by stabilizing the enzyme–DNA cleavable complex and induce a degradation of the enzymes through the 26S proteasome system. A plausible link between sumoylation and degradation has not yet been elucidated. We demonstrate here that topoisomerase IIβ, but not its isoform IIα, is selectively degraded through proteasome by exposure to the catalytic inhibitor ICRF-193 which does not damage DNA. The β isoform immunoprecipitated from ICRF-treated cells was modified by multiple modifiers, SUMO-2/3, SUMO-1, and polyubiquitin. When the SUMO conjugating enzyme Ubc9 was conditionally knocked out, the ICRF-induced degradation of topoisomerase IIβ did not occur, suggesting that the SUMO modification pathway is essential for the degradation.
- Subjects
DNA topoisomerases; POLYACRYLAMIDE gel electrophoresis
- Publication
FEBS Letters, 2003, Vol 546, Issue 2/3, p374
- ISSN
0014-5793
- Publication type
Article
- DOI
10.1016/S0014-5793(03)00637-9