The rapid inactivation of nuclear tyrosine phosphorylated Stat1 depends upon a protein tyrosine phosphatase.
AUTOR(ES)
Haspel, R L
RESUMO
After interferon-gamma (IFN-gamma) treatment of cells the appearance of tyrosine phosphorylated Stat1 in the nucleus was maximal within 20-30 min, remained for 2-2.5 h and activated molecules disappeared by 4 h. In the absence of continued signaling from the receptor (imposed by staurosporine treatment) previously activated Stat1 disappeared completely within 60 min, implying continuous generation and removal of active molecules during extended IFN-gamma treatment. Proteasome inhibitors prolonged the time of activation of Stat1 by prolonging signaling from the receptor but not by blocking removal of already activated Stat1 molecules. By analyzing with 35S labeling the distribution of total Stat1 and activated Stat1, we concluded that the Stat1 molecules promptly cycle into the nucleus as tyrosine phosphorylated molecules and later return quantitatively to the cytoplasm as non-phosphorylated molecules. Therefore, the removal of the activated Stat1 molecules from the nucleus appears not to be proteolytic but must depend on a protein tyrosine phosphatase(s).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=452449Documentos Relacionados
- A nuclear protein tyrosine phosphatase is required for the inactivation of Stat1
- Identification of a Nuclear Stat1 Protein Tyrosine Phosphatase
- Nuclear localization of the PEP protein tyrosine phosphatase.
- Inactivation of Mammalian Target of Rapamycin Increases STAT1 Nuclear Content and Transcriptional Activity in α4- and Protein Phosphatase 2A-dependent Fashion*
- DNA binding controls inactivation and nuclear accumulation of the transcription factor Stat1