PURPOSE Topoisomerases (types: I/IIa-b/IIIa-b) represent a super-family of nucleic enzymes involved in the DNA replication, transcription, recombination, and also chromosome topological formation. Topoisomerase's I (Topo I- gene location: 20q12) aberrant expression is a frequent genetic event in a variety of solid malignancies. Topo I inhibition promotes cell death due to DNA damage and for thi...

The nonconserved, hydrophilic N-terminal domain of eukaryotic DNA topoisomerase I (topo I) is dispensable for catalytic activity in vitro but essential in vivo. There are at least five putative nuclear localization signals and a nucleolin-binding signal within the first 215 residues of the topo I N-terminal domain. We have investigated physiological functions of the topo I N-terminal domain by ...

Together, RecQ helicase and topoisomerase III (Topo III) of Escherichia coli comprise a potent DNA strand passage activity that can catenate covalently closed DNA (Harmon, F. G., DiGate, R. J., and Kowalczykowski, S. C. (1999) Mol. Cell 3, 611-620). Here we directly assessed the structure of the catenated DNA species formed by RecQ helicase and Topo III using atomic force microscopy. The images...

The aims of this study were to determine whether the expression of Topo II-α correlates with presence of EBV in giant cell lesion of the jawbones and whether it is predictive of clinical biologic behavior of these lesions. Paraffin-embedded tissues from 8 recurrent and 7 nonrecurrent cases of bony GCLs and 9 peripheral giant cell lesions (PGCLs) as a control group were assessed for the expressi...

OBJECTIVE The aim of this study was to determine whether the activity of topoisomerase I (topo I), the target of the anti-neoplastic drug camptothecin (CPT), is elevated in cervical cancer and whether CPT can radiosensitize cervical tumors. METHODS The topo I activity of 11 normal cervix and 30 cervical carcinoma tumors was assayed by measuring the relaxation of supercoiled DNA. Subconfluent ...

DNA topoisomerase IIalpha (topo IIalpha) is an essential nuclear enzyme and its unique decatenation activity has been implicated in many aspects of chromosome dynamics such as chromosome replication and segregation during mitosis. Here we show that chromatin-associated protein HMGB1 (a member of the large family of HMG-box proteins with possible functions in DNA replication, transcription, reco...

DNA topoisomerase (topo) II inhibitors either stabilize DNA-topo II complexes by blocking DNA religation (e.g. etoposide) or block the enzyme's catalytic activity (e.g. dexrazoxane). The former class of drugs causes direct DNA damage through topo II, while the latter class does not, but both classes cause apoptosis. We cloned the Fas ligand (FasL) promoter and coupled it to the luciferase gene....

Chromosome partitioning in Escherichia coli is assisted by two interacting proteins, topoisomerase (topo) IV and MukB. MukB stimulates the relaxation of negative supercoils by topo IV; to understand the mechanism of their action and to define this functional interplay, we determined the crystal structure of a minimal MukB-topo IV complex to 2.3 Å resolution. The structure shows that the so-call...

OBJECTIVES To report on a novel IIF pattern specifically associated with antibodies to DNA topo I. METHODS A novel compound IF pattern, designated Scl-70 pattern, was characterized in routine ANA-HEp-2 IIF screening. Within the last 3 years, all serum samples presenting the Scl-70 pattern at the ANA-HEp2 IIF screening were tested for anti-topo I reactivity. Conversely, 16 serum samples with k...

INTRODUCTION The presence of anti-topoisomerase I (topo I) antibodies is a classic scleroderma (SSc) marker presumably associated with a unique clinical subset. Here the clinical association of anti-topo I was reevaluated in unselected patients seen in a rheumatology clinic setting. METHODS Sera from the initial visit in a cohort of unselected rheumatology clinic patients (n = 1,966, includin...