Yun Jeanho, Chae Hee-Don, Choi Tae-Saeng, Kim Eun-Hee, Bang Yung-Jue, Chung Jongkyeong, Choi Kyeong-Sook, Mantovani Roberto, Shin Deug Y
National Research Laboratory, Department of Microbiology, Dankook University College of Medicine, Cheonan, 330-714, Korea.
J Biol Chem. 2003 Sep 19;278(38):36966-72. doi: 10.1074/jbc.M305178200. Epub 2003 Jul 11.
Recent studies have suggested that the NF-Y transcription factor is involved in transcription repression of the cell cycle regulatory genes in a response to p53 induction or DNA damage. Here we demonstrate the cdk2-dependent phosphorylation of NF-Y and its involvement in transcription repression by the p53-p21 signaling pathway. Cdk2 phosphorylates two serine residues near the DNA-binding domain of the YA subunit of NF-Y. Cyclin A-cdk2 appears to associate with NF-Y both in vitro and in vivo. Furthermore, YA protein is phosphorylated in parallel with a cell cycle-dependent activation of cdk2 kinase and cyclin A expression. YA phosphorylation is unnecessary for heterotrimer formation with the YB-YC dimer. However, NF-Y containing a phosphorylation-deficient mutant form of YA, YA-aa, has its DNA binding activity impaired. Consistently, YA-aa inhibits transcription activation of a NF-Y target promoter, cdc2, by cdk2. These results facilitate the elucidation of the regulatory mechanisms of cell cycle progression involving the p21-cdk2-NF-Y signaling pathway.
最近的研究表明，NF-Y转录因子在响应p53诱导或DNA损伤时参与细胞周期调控基因的转录抑制。在此，我们证明了NF-Y的cdk2依赖性磷酸化及其通过p53-p21信号通路参与转录抑制。Cdk2使NF-Y的YA亚基DNA结合结构域附近的两个丝氨酸残基磷酸化。细胞周期蛋白A-cdk2似乎在体外和体内均与NF-Y相关联。此外，YA蛋白的磷酸化与cdk2激酶的细胞周期依赖性激活和细胞周期蛋白A的表达同时发生。YA磷酸化对于与YB-YC二聚体形成异源三聚体并非必需。然而，含有YA磷酸化缺陷突变体形式（YA-aa）的NF-Y的DNA结合活性受损。一致地，YA-aa抑制cdk2对NF-Y靶启动子cdc2的转录激活。这些结果有助于阐明涉及p21-cdk2-NF-Y信号通路的细胞周期进程的调控机制。
