The Suppression of the Synthesis of a Nuclear Protein in Cells Blocked in G 2 Phase: Identification of NP-170 as Topoisomerase II

1992 ◽  
Vol 132 (2) ◽  
pp. 162 ◽  
Author(s):  
P. C. Goswami ◽  
M. Hill ◽  
R. Higashikubo ◽  
W. D. Wright ◽  
J. L. Roti Roti
Keyword(s):  
Topoisomerase Ii ◽  
Nuclear Protein ◽  
Phase Identification ◽  
In Cells

How Many Pathways Are Available for Nuclear Protein Import in Cells

2002 ◽  
Vol 35 (6) ◽  
pp. 435-440 ◽  
Author(s):  
Yoshihiro Yoneda ◽  
Ai Kametaka ◽  
Toshihiro Sekimoto
Keyword(s):  
Protein Import ◽  
Nuclear Protein ◽  
Nuclear Protein Import ◽  
In Cells

scholarly journals Interactions of antitumor triazoloacridinones with DNA.

2007 ◽  
Vol 54 (2) ◽  
pp. 297-306 ◽  
Author(s):  
Marcin Koba ◽  
Jerzy Konopa
Keyword(s):  
Topoisomerase Ii ◽  
Cultured Cells ◽  
Metabolic Activation ◽  
Cytotoxic Action ◽  
Dependent Manner ◽  
Interstrand Crosslinks ◽  
Chemical Structures ◽  
Antitumor Compounds ◽  
Preclinical Trials ◽  
In Cells

Triazoloacridinones (TA) are a new group of potent antitumor compounds, from which the most active derivative, C-1305, has been selected for extended preclinical trials. This study investigated the mechanism of TA binding to DNA. Initially, for selected six TA derivatives differing in chemical structures as well as cytotoxicity and antitumor activity, the capability of noncovalent DNA binding was analyzed. We showed that all triazoloacridinones studied stabilized the DNA duplex at a low-concentration buffer but not at a salt concentration corresponding to that in cells. DNA viscometric studies suggested that intercalation to DNA did not play a major role in the mechanism of the cytotoxic action of TA. Studies involving cultured cells revealed that triazoloacridinone C-1305 after previous metabolic activation induced the formation of interstrand crosslinks in DNA of some tumor and fibroblast cells in a dose dependent manner. However, the detection of crosslink formation was possible only when the activity of topoisomerase II in cells was lowered. Furthermore, it was impossible to validate the relevance of the ability to crosslink DNA to biological activity of TA derivatives.

scholarly journals Vaccinia Virus DNA Ligase Recruits Cellular Topoisomerase II to Sites of Viral Replication and Assembly

2008 ◽  
Vol 82 (12) ◽  
pp. 5922-5932 ◽  
Author(s):  
Y.-C. James Lin ◽  
Jianhong Li ◽  
Chad R. Irwin ◽  
Heather Jenkins ◽  
Luke DeLange ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Virus Replication ◽  
Topoisomerase Ii ◽  
Nuclear Dna ◽  
Wild Type Virus ◽  
Dna Ligase ◽  
Topoisomerase Iiα ◽  
Bait Protein ◽  
Y Substitution ◽  
In Cells

ABSTRACT Vaccinia virus replication is inhibited by etoposide and mitoxantrone even though poxviruses do not encode the type II topoisomerases that are the specific targets of these drugs. Furthermore, one can isolate drug-resistant virus carrying mutations in the viral DNA ligase and yet the ligase is not known to exhibit sensitivity to these drugs. A yeast two-hybrid screen was used to search for proteins binding to vaccinia ligase, and one of the nine proteins identified comprised a portion (residue 901 to end) of human topoisomerase IIβ. One can prevent the interaction by introducing a C11-to-Y substitution mutation into the N terminus of the ligase bait protein, which is one of the mutations conferring etoposide and mitoxantrone resistance. Coimmunoprecipitation methods showed that the native ligase and a Flag-tagged recombinant protein form complexes with human topoisomerase IIα/β in infected cells and that this interaction can also be disrupted by mutations in the A50R (ligase) gene. Immunofluorescence microscopy showed that both topoisomerase IIα and IIβ antigens are recruited to cytoplasmic sites of virus replication and that less topoisomerase was recruited to these sites in cells infected with mutant virus than in cells infected with wild-type virus. Immunoelectron microscopy confirmed the presence of topoisomerases IIα/β in virosomes, but the enzyme could not be detected in mature virus particles. We propose that the genetics of etoposide and mitoxantrone resistance can be explained by vaccinia ligase binding to cellular topoisomerase II and recruiting this nuclear enzyme to sites of virus biogenesis. Although other nuclear DNA binding proteins have been detected in virosomes, this appears to be the first demonstration of an enzyme being selectively recruited to sites of poxvirus DNA synthesis and assembly.

Nuclear protein import is reduced in cells expressing nuclear envelopathy-causing lamin A mutants

2009 ◽  
Vol 315 (14) ◽  
pp. 2373-2385 ◽  
Author(s):  
Albert Busch ◽  
Tilman Kiel ◽  
Wolfgang-M. Heupel ◽  
Manfred Wehnert ◽  
Stefan Hübner
Keyword(s):  
Protein Import ◽  
Nuclear Protein ◽  
Lamin A ◽  
Nuclear Protein Import ◽  
In Cells

E2F-Dependent Repression of Topoisomerase II Regulates Heterochromatin Formation and Apoptosis in Cells with Melanoma-Prone Mutation

2005 ◽  
Vol 65 (10) ◽  
pp. 4067-4077 ◽  
Author(s):  
Wan Jiao ◽  
Huei-Min Lin ◽  
Jamie Timmons ◽  
Akhilesh K. Nagaich ◽  
Shu-Wing Ng ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
Heterochromatin Formation ◽  
In Cells

scholarly journals Effect of TDP2 on the Level of TOP2-DNA Complexes and SUMOylated TOP2-DNA Complexes

2018 ◽  
Vol 19 (7) ◽  
pp. 2056 ◽  
Author(s):  
Ka Lee ◽  
Rebecca Swan ◽  
Zbyslaw Sondka ◽  
Kay Padget ◽  
Ian Cowell ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
K562 Cells ◽  
Strand Break ◽  
Dna Complexes ◽  
Dna Topoisomerase ◽  
Strand Breaks ◽  
Sumo Ligase ◽  
Dna Complex ◽  
In Cells

DNA topoisomerase II (TOP2) activity involves a normally transient double-strand break intermediate in which the enzyme is coupled to DNA via a 5′-phosphotyrosyl bond. However, etoposide and other topoisomerase drugs poison the enzyme by stabilising this enzyme-bridged break, resulting in the accumulation of TOP2-DNA covalent complexes with cytotoxic consequences. The phosphotyrosyl diesterase TDP2 appears to be required for efficient repair of this unusual type of DNA damage and can remove 5′-tyrosine adducts from a double-stranded oligonucleotide substrate. Here, we adapt the trapped in agarose DNA immunostaining (TARDIS) assay to investigate the role of TDP2 in the removal of TOP2-DNA complexes in vitro and in cells. We report that TDP2 alone does not remove TOP2-DNA complexes from genomic DNA in vitro and that depletion of TDP2 in cells does not slow the removal of TOP2-DNA complexes. Thus, if TDP2 is involved in repairing TOP2 adducts, there must be one or more prior steps in which the protein-DNA complex is processed before TDP2 removes the remaining 5′ tyrosine DNA adducts. While this is partly achieved through the degradation of TOP2 adducts by the proteasome, a proteasome-independent mechanism has also been described involving the SUMOylation of TOP2 by the ZATT E3 SUMO ligase. The TARDIS assay was also adapted to measure the effect of TDP2 knockdown on levels of SUMOylated TOP2-DNA complexes, which together with levels of double strand breaks were unaffected in K562 cells following etoposide exposure and proteasomal inhibition.

Sign in / Sign up

Export Citation Format

Share Document