PMA Activates Stat3 in the Jak/Stat Pathway and Induces SOCS5 in Rat Brain Astrocytes

  • Hwang, Mi-Na (Research Institute, National Cancer Center) ;
  • Kim, Kwang Soo (Department of Pharmacology, Ajou University School of Medicine) ;
  • Choi, Yo-Woo (Research Institute, National Cancer Center) ;
  • Jou, Ilo (Department of Pharmacology, Ajou University School of Medicine) ;
  • Yoon, Sungpil (Research Institute, National Cancer Center)
  • Received : 2006.08.24
  • Accepted : 2006.12.07
  • Published : 2007.02.28


Suppressors of cytokine signaling (SOCS) family members are negative feedback regulators of the Jak/Stat pathway, which is an essential inflammatory signaling pathway. We investigated expression of eight members of the SOCS family in rat astrocytes, using two inflammatory stimulants, PMA and IFN-${\gamma}$. Only a few SOCS genes were induced by both stimulants, and we detected an increase in SOCS5 protein with PMA. PMA activated the Jnk, Erk, p38, and Jak/Stat signal pathways. In addition, it increased the level of activated-Stat3 resulting from tyrosine phosphorylation. A gel-shift assay showed that a protein in nuclear extracts from PMA-treated cells was able to bind to Stat binding elements. These results suggest that activated Stat3 binds to SOCS promoters and leads to their transcriptional induction.




Supported by : National Cancer Center


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