Cyclin E-CDK2 Protein Phosphorylates Plant Homeodomain Finger Protein 8 (PHF8) and Regulates Its Function in the Cell Cycle----中国科学院微生物研究所

科研成果

论文题目:	Cyclin E-CDK2 Protein Phosphorylates Plant Homeodomain Finger Protein 8 (PHF8) and Regulates Its Function in the Cell Cycle
作者:	Sun Liping Huang Yan, Wei Qian, Tong Xiaomei, Cai Rong, Nalepa Grzegorz, Ye Xin*.
联系作者:
刊物名称:	J Biol Chem
期:	290
卷:	7
页:	4075-85
年份:	2015
影响因子:	4.863
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摘要:	Cyclin E-CDK2 is a key regulator in G1/S transition. Previously, we identified a number of CDK2-interacting proteins, including PHF8 (plant homeodomain finger protein 8). In this report, we confirmed that PHF8 is a novel cyclin E-CDK2 substrate. By taking the approach of mass spectrometry, we identified that PHF8 Ser-844 is phosphorylated by cyclin E-CDK2. Immunoblotting analysis indicated that WT PHF8 demethylates histone H3K9me2 more efficiently than the cyclin E-CDK2 phosphorylation-deficient PHF8-S844A mutant. Furthermore, flow cytometry analysis showed that WT PHF8 promotes S phase progression more robustly than PHF8-S844A. Real-time PCR results demonstrated that PHF8 increases transcription of cyclin E, E2F3, and E2F7 to significantly higher levels compared with PHF8-S844A. Further analysis by ChIP assay indicated that PHF8 binds to the cyclin E promoter stronger than PHF8-S844A and reduces the H3K9me2 level at the cyclin E promoter more efficiently than PHF8-S844A. In addition, we found that cyclin E-CDK2-mediated phosphorylation of PHF8 Ser-844 promotes PHF8-dependent rRNA transcription in luciferase reporter assays and real-time PCR. Taken together, these results indicate that cyclin E-CDK2 phosphorylates PHF8 to stimulate its demethylase activity to promote rRNA transcription and cell cycle progression.