The human topoisomerase I damage response plays a role in apoptosis.
Previous studies have shown that human topoisomerase I cleavage complexes form as a response to various DNA damages in vivo, the so called human topoisomerase I "damage response". It was suggested that this damage response may play a role in DNA repair as well as in apoptosis, but only very few investigations have been done and the significance of the damage response still remains unclear. Here we demonstrate that human topoisomerase I cleavage complexes induced by high doses of UV irradiation are highly stable for up to 48 h. Furthermore, we show that human topoisomerase I cleavage complexes correlate with apoptosis. However, at low UV doses the cleavage complex level was very low and the complexes were repaired. Surprisingly, we found that high levels of stable cleavage complexes were not only found in UV-irradiated cells but also in untreated cells that underwent apoptosis. A possible role of human topoisomerase I in apoptosis is discussed.
Søe
Kent
K
Department of Biochemistry, Institute of Molecular Biotechnology, Beutenbergstrasse 11, D-07745 Jena, Germany. kent@imb-jena.de
Rockstroh
Anja
A
Schache
Peter
P
Grosse
Frank
F
D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D004264:DNA Topoisomerases, Type I / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans
D004264:DNA Topoisomerases, Type I