A ubiquitin-proteasome pathway for the repair of topoisomerase I-DNA covalent complexes

Chao P. Lin, Yi Ban, Yi Lisa Lyu, Shyamal D. Desai, Leroy-Fong Liu

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Reversible topoisomerase I (Top1)-DNA cleavage complexes are the key DNA lesion induced by anticancer camptothecins (e.g. topotecan and irinotecan) as well as structurally perturbed DNAs (e.g. oxidatively damaged DNA, UV-irradiated DNA, alkylated DNA, uracil-substituted DNA, mismatched DNA, gapped and nicked DNA, and DNA with abasic sites). Top1 cleavage complexes arrest transcription and trigger transcription-dependent degradation of Top1, a phenomenon termed Top1 down-regulation. In the current study, we have investigated the role of Top1 down-regulation in the repair of Top1 cleavage complexes. Using quiescent (serum-starved) human WI-38 cells, camptothecin (CPT) was shown to induce Top1 down-regulation, which paralleled the induction of DNA single-strand breaks (SSBs) (assayed by comet assays) and ATM autophosphorylation (at Ser-1981). Interestingly, Top1 down-regulation, induction of DNA SSBs and ATM autophosphorylation were all abolished by the proteasome inhibitor MG132. Furthermore, studies using immunoprecipitation and dominant-negative ubiquitin mutants have suggested a specific requirement for the assembly of Lys-48-linked polyubiquitin chains for CPT-induced Top1 down-regulation. In contrast to the effect of proteasome inhibition, inactivation of PARP1 was shown to increase the amount of CPT-induced SSBs and the level of ATM autophosphorylation. Together, these results support a model in which Top1 cleavage complexes arrest transcription and activate a ubiquitin-proteasome pathway leading to the degradation of Top1 cleavage complexes. Degradation of Top1 cleavage complexes results in the exposure of Top1-concealed SSBs for repair through a PARP1-dependent process.

Original languageEnglish
Pages (from-to)21074-21083
Number of pages10
JournalJournal of Biological Chemistry
Volume283
Issue number30
DOIs
Publication statusPublished - Jul 25 2008
Externally publishedYes

Fingerprint

Type I DNA Topoisomerase
Proteasome Endopeptidase Complex
Ubiquitin
Repair
Camptothecin
DNA
Down-Regulation
Automatic teller machines
Single-Stranded DNA Breaks
Transcription
irinotecan
Degradation
Polyubiquitin
Topotecan
DNA Cleavage
Proteasome Inhibitors
Comet Assay
Uracil
Immunoprecipitation
Assays

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

A ubiquitin-proteasome pathway for the repair of topoisomerase I-DNA covalent complexes. / Lin, Chao P.; Ban, Yi; Lyu, Yi Lisa; Desai, Shyamal D.; Liu, Leroy-Fong.

In: Journal of Biological Chemistry, Vol. 283, No. 30, 25.07.2008, p. 21074-21083.

Research output: Contribution to journalArticle

Lin, Chao P. ; Ban, Yi ; Lyu, Yi Lisa ; Desai, Shyamal D. ; Liu, Leroy-Fong. / A ubiquitin-proteasome pathway for the repair of topoisomerase I-DNA covalent complexes. In: Journal of Biological Chemistry. 2008 ; Vol. 283, No. 30. pp. 21074-21083.
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