Journal Article

Phosphorylation of topoisomerase I in L5178Y-S cells is associated with poly(ADP-ribose) metabolism

Krzysztof Staron, Barbara Kowalska-Loth, Krzysztof Nieznanski and Irena Szumiel

in Carcinogenesis

Volume 17, issue 3, pages 383-387
Published in print March 1996 | ISSN: 0143-3334
e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/17.3.383
Phosphorylation of topoisomerase I in L5178Y-S cells is associated with poly(ADP-ribose) metabolism

More Like This

Show all results sharing this subject:

  • Clinical Cytogenetics and Molecular Genetics

GO

Show Summary Details

Preview

The reason for different phosphorylation of topoisomerase I in two sublines of L5178Y murine lymphoma (LY cells) was investigated. Camptothecin-resistant LY-S cells show increased poly(ADP-ribose) level and lowered topoisomerase I phosphorylation compared to camptothecin-sensitive LY-R cells. In this study diminished phosphorylation of LY-S topoisomerase I was observed for sites recognized by casein kinase 2 but not for those phosphorylated by protein kinase C. Tryptic digests of LY-S topoisomerase I labeled in vitro by casein kinase 2 indicated that phosphorylation was similarly lowered at different sites. Activity of casein kinase 2 measured in nuclear extracts was about 1.7 times lower for LY-S than LY-R cells. This difference was diminished or eliminated by increasing casein concentration, diluting the extract or increasing the ionic strength. Activity of poly(ADP-ribose) polymerase was 5.3 times higher in LY-S than in LY-R nuclei. When the activity of the polymerase was inhibited by treatment of LY-S cells with benzamide, casein kinase 2-catalyzed phosphorylation of topoisomerase I increased. This was accompanied by an increase in sensitivity to camptothecin as reflected in the diminished viability of LY-S cells.

Journal Article.  0 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.