Computational and Biochemical Discovery of RSK2 as a Novel Target for Epigallocatechin Gallate (EGCG)

• Published in: PloS one 2015-06, Vol.10 (6), p.e0130049-e0130049
• Main Authors: Chen, Hanyong, Yao, Ke, Chang, Xiaoyu, Shim, Jung-Hyun, Kim, Hong-Gyum, Malakhova, Margarita, Kim, Dong-Joon, Bode, Ann M, Dong, Zigang
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Analysis; Animals; Assaying; ATP; Binding, Competitive; Catalysis; Catalytic Domain; Catechin; Catechin - analogs & derivatives; Catechin - metabolism; Catechin - pharmacology; Cell Line; Cell Survival - drug effects; Cellular signal transduction; Chang, Jung; Computation; Computational Biology; Computer applications; Computer terminals; Docking; Drug Evaluation, Preclinical; Embryo fibroblasts; Embryos; Epidermal growth factor; Epidermal Growth Factor - pharmacology; Epigallocatechin gallate; Epigallocatechin-3-gallate; Fibroblasts; Green tea; Histone H3; Identification methods; Mice; Molecular chains; Molecular Docking Simulation; Molecular Targeted Therapy; Phosphorylation; Protein Kinase Inhibitors - metabolism; Protein Kinase Inhibitors - pharmacology; Protein-serine/threonine kinase; Proteins; Ribosomal protein S6 kinase; Ribosomal Protein S6 Kinases, 90-kDa - antagonists & inhibitors; Ribosomal Protein S6 Kinases, 90-kDa - chemistry; Ribosomal Protein S6 Kinases, 90-kDa - metabolism; Tea; Threonine; Transformation; Viability
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0130049

The most active anticancer component in green tea is epigallocatechin-3-gallate (EGCG). Protein interaction with EGCG is a critical step for mediating the effects of EGCG on the regulation of various key molecules involved in signal transduction. By using computational docking screening methods for protein identification, we identified a serine/threonine kinase, 90-kDa ribosomal S6 kinase (RSK2), as a novel molecular target of EGCG. RSK2 includes two kinase catalytic domains in the N-terminal (NTD) and the C-terminal (CTD) and RSK2 full activation requires phosphorylation of both terminals. The computer prediction was confirmed by an in vitro kinase assay in which EGCG inhibited RSK2 activity in a dose-dependent manner. Pull-down assay results showed that EGCG could bind with RSK2 at both kinase catalytic domains in vitro and ex vivo. Furthermore, results of an ATP competition assay and a computer-docking model showed that EGCG binds with RSK2 in an ATP-dependent manner. In RSK2+/+ and RSK2-/- murine embryonic fibroblasts, EGCG decreased viability only in the presence of RSK2. EGCG also suppressed epidermal growth factor-induced neoplastic cell transformation by inhibiting phosphorylation of histone H3 at Ser10. Overall, these results indicate that RSK2 is a novel molecular target of EGCG.