Human ARF protein interacts with topoisomerase I and stimulates its activity.
The ARF gene (p19(ARF) in mouse and p14(ARF) in man) has become a central actor of the cell cycle regulation process as it participates to the ARF-MDM2-p53 pathway and the Rb-E2F-1 pathway. By use of immunoprecipitation and Western blotting (IP/WB), we now show that ARF physically associates with topoisomerase I (Topo I). ARF-Topo I immune complexes were detected in SF9 insect cells infected with recombinant baculoviruses encoding the two genes as well as in 293 cells that express endogenously these proteins. Preparations of a GST-ARF recombinant protein stimulated the DNA relaxation activity of Topo I but, in contrast, had no effect on the decatenation activity of Topo II. The Topo I stimulation was also detected in cell extracts of SF9 cells expressing both proteins. A confocal microscopy study indicated that part of ARF and Topo I colocalized in the granular component structure of the nucleolus. As a whole, our data indicate that Topo I is a new partner of ARF and suggest that ARF is involved in cell reactions that require Topo I.
Karayan
L
L
Laboratoire d'Oncologie Moléculaire, FRE 2224 CNRS, Poitiers Cedex, France.
Riou
J F
JF
Séité
P
P
Migeon
J
J
Cantereau
A
A
Larsen
C J
CJ
D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002451:Cell Compartmentation; D002466:Cell Nucleolus / Q000378:metabolism; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D018411:Spodoptera / Q000166:cytology; D025803:Tumor Suppressor Protein p14ARF
D019941:Cyclin-Dependent Kinase Inhibitor p16; D011506:Proteins; D011994:Recombinant Proteins; D025803:Tumor Suppressor Protein p14ARF; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II