Activation of rDNA transcription by FGF-2: key role of protein kinase CKII.
Basic Fibroblast Growth Factor-2 (FGF-2) promotes G1 to S transition of quiescent sparse adult bovine aortic endothelial cells. In addition to signal transduction through interaction with tyrosine kinase high affinity receptor, FGF-2 is translocated to the nucleus and accumulated into the nucleolus. These data suggest that FGF-2 functions directly in nuclear events. In vivo, correlations were established between the entrance of FGF-2 into the nucleus and an increase in rDNA transcription and in protein phosphorylation. In vitro, in experiments carried out with nuclei isolated from quiescent cells, addition of FGF-2 increases rDNA transcription by a factor of 5 and also increases protein phosphorylation. Nucleolin, a factor involved in control of rDNA transcription is preferentially phosphorylated. It has been shown that nucleolin and other factors implicated in rDNA transcription are substrates of protein kinase CKII. Using purified kinase CKII and nucleolin in an in vitro phosphorylation assay, we have shown that FGF-2 activates the protein kinase activity. These results suggest that FGF-2 could act as an activator of rDNA transcription through interactions with the protein kinase CKII.
Bouche
G
G
Laboratoire de Biologie Moléculaire Eucaryote, du CNRS et Université Paul Sabatier, Toulouse.
Baldin
V
V
Belenguer
P
P
Prats
H
H
Amalric
F
F
D000818:Animals; D001011:Aorta; D047390:Casein Kinase II; D002417:Cattle; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004275:DNA, Ribosomal / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D016193:G1 Phase / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D012335:RNA, Ribosomal / Q000096:biosynthesis* / Q000235:genetics; D016601:RNA-Binding Proteins; D015398:Signal Transduction / Q000187:drug effects; D013268:Stimulation, Chemical; D014158:Transcription, Genetic / Q000187:drug effects*; D000097796:Nucleolin
D047390:Casein Kinase II; D004275:DNA, Ribosomal; D016222:Fibroblast Growth Factor 2; D009687:Nuclear Proteins; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; D000097796:Nucleolin