Binding of FGF-1 variants to protein kinase CK2 correlates with mitogenicity.
Fibroblast growth factor-1 (FGF-1) has both extra- and intracellular functions. To identify intracellular binding partners for FGF-1, we isolated proteins from U2OS human osteosarcoma cells interacting specifically with FGF-1. One of the isolated proteins was identified as protein kinase CK2 (CK2). We here provide evidence that FGF-1 binds to both the catalytic alpha-subunit and to the regulatory beta-subunit of CK2. The interaction between FGF-1 and CK2 alpha and beta was characterized by surface plasmon resonance, giving K(D) values of 0.4 +/- 0.3 and 1.2 +/- 0.2 microM, respectively. By using a novel assay for intracellular protein interaction, FGF-1 and CK2 alpha are shown to interact in vivo. In vitro, FGF-1 and FGF-2 are phosphorylated by CK2, and the presence of FGF-1 or FGF-2 was found to enhance the autophosphorylation of CK2 beta. A correlation between the mitogenic potential of FGF-1 mutants and their ability to bind to CK2 alpha was observed. The possible involvement of CK2 in the FGF-induced stimulation of DNA synthesis is discussed.
Skjerpen
Camilla Skiple
CS
Department of Biochemistry at The Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway.
Nilsen
Trine
T
Wesche
Jørgen
J
Olsnes
Sjur
S
D019943:Amino Acid Substitution; D001665:Binding Sites; D001859:Bone Neoplasms / Q000473:pathology; D047390:Casein Kinase II; D004261:DNA Replication; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D020935:MAP Kinase Signaling System; D046911:Macromolecular Substances; D008938:Mitosis / Q000502:physiology; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism; D012516:Osteosarcoma / Q000473:pathology; D020675:Peroxisomes / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D020349:Surface Plasmon Resonance; D014162:Transfection; D014407:Tumor Cells, Cultured
D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D016220:Fibroblast Growth Factor 1; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases