Bouche G, Baldin V, Belenguer P, Prats H, Amalric F
Laboratoire de Biologie Moléculaire Eucaryote, du CNRS et Université Paul Sabatier, Toulouse.
Cell Mol Biol Res. 1994;40(5-6):547-54.
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.
碱性成纤维细胞生长因子-2（FGF-2）促进静止稀疏的成年牛主动脉内皮细胞从G1期向S期转变。除了通过与酪氨酸激酶高亲和力受体相互作用进行信号转导外，FGF-2还会转位至细胞核并积聚在核仁中。这些数据表明FGF-2直接在核事件中发挥作用。在体内，FGF-2进入细胞核与rDNA转录增加以及蛋白质磷酸化增加之间建立了相关性。在体外，在用从静止细胞中分离出的细胞核进行的实验中，添加FGF-2可使rDNA转录增加5倍，同时也增加蛋白质磷酸化。核仁素是一种参与rDNA转录调控的因子，它被优先磷酸化。已经表明，核仁素和其他参与rDNA转录的因子是蛋白激酶CKII的底物。在体外磷酸化试验中使用纯化的激酶CKII和核仁素，我们已经表明FGF-2激活了蛋白激酶活性。这些结果表明，FGF-2可能通过与蛋白激酶CKII相互作用而作为rDNA转录的激活剂。
