title: Identification of the oncogenic kinase TOPK/PBK as a master mitotic regulator of C2H2 zinc finger proteins.
abstract: TOPK/PBK is an oncogenic kinase upregulated in most human cancers and its high expression correlates with poor prognosis. TOPK is known to be activated by Cdk1 and needed for mitotic cell division; however, its mitotic functions are not yet fully understood. In this study, we show that TOPK plays a global mitotic role by simultaneously regulating hundreds of DNA binding proteins. C2H2 zinc finger proteins (ZFPs) constitute the largest family of human proteins. All C2H2 ZFPs contain a highly conserved linker sequence joining their multi-zinc finger domains. We have previously shown that phosphorylation of this conserved motif serves as a global mechanism for the coordinate dissociation of C2H2 ZFPs from condensing chromatin, during mitosis. Here, using a panel of kinase inhibitors, we identified K252a as a potent inhibitor of mitotic ZFP linker phosphorylation. We generated a biotinylated form of K252a and used it to purify candidate kinases. From these candidates we identified TOPK/PBK, in vitro and in vivo, as the master ZFP linker kinase. Furthermore, we show precise temporal correlation between TOPK activating phosphorylation by Cdk1 and linker phosphorylation in mitosis. The identification of this fundamental role of TOPK underscores its significance as a promising novel target of cancer therapeutics.
authors.affiliation: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, 32306, United States of America.
authors.forename: Raed
authors.initials: R
authors.lastname: Rizkallah
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, 32306, United States of America.
authors.forename: Paratchata
authors.initials: P
authors.lastname: Batsomboon
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, 32306, United States of America.
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Dudley
authors.affiliation: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, 32306, United States of America.
authors.forename: Myra M
authors.initials: MM
authors.lastname: Hurt
mesh_terms: D002227:Carbazoles / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D026121:Indole Alkaloids / Q000494:pharmacology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012097:Repressor Proteins
chemical_list: C486563:BCL11A protein, human; D002227:Carbazoles; D002352:Carrier Proteins; D026121:Indole Alkaloids; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D012097:Repressor Proteins; C049985:staurosporine aglycone; D020929:Mitogen-Activated Protein Kinase Kinases; C409022:PDZ-binding kinase