RSK2Mediates THP-1Monocyte Differentiation Into Macrophage Through Regulation Of STAT2Activity

STAT2is a member of STATs family. JAK/STAT signal pathway is the classical pathway for STATs activation. STAT2acquires transcription activity after its tyrosine phosphorylation by JAK. RSK2is a member of Serine/Threonine kinase family, which phosphorylates many kinds of substrates resulting in differentiation, apoptosis and survival.Objective:To investigate the mechanism of THP-1monocyte differentiation into macrophage through regulation of STAT2activity by RSK2.Methods:The binding of RSK2and STAT2was assayed by CheckMateTM Mammalian Two-Hybrid system. The further confirmation of their association and the key domains of the RSK2which bound to STAT2were assayed by plasmids transfection and co-immunoprecipitation. The transcription activity of STAT2regulated by RSK2was detected by luciferase reporter system. The nuclear translocation of STAT2induced by RSK2was observed by fluorescence microscope and Western blot analysis of the isolates of the cytoplasm and nuclear protein. The phosphorylation of STAT2was detected by In vitro kinase assay and co-immunoprecipitation analysis in vivo. Finally, the morphological changes of the cells were tested by microscope methodology and flow cytometry. The adherent rate was indirectly investigated by XXT.Results:RSK2binds STAT2through the N-terminal domain and phosphorylates STAT2to promote its transcription activity and nuclear translocation upon PMA stimulation. Several potential serines phosphorylated have been found in the N-terminal and C-terminal of STAT2. In addition, RSK2mediates THP-1monocyte differentiation into macrophage through regulation of STAT2activity.Conclusion:RSK2was activated by MAPK/ERK1/2pathway upon the stimulation of PMA. Active RSK2phosphorylates STAT2, resulting in STAT2nuclear translocation to exert its transcription function. The interaction between RSK2and STAT2promotes THP-1monocytes differentiating into macrophages stimulated by PMA.Our findings revealed a new way to activate STAT2, and apply some new data to elucidate mechanism for STAT2involved in certain cell biological behaviors.