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Osmotic regulation of STAT3 stability in H4IIE rat hepatoma cells
Author(s) -
Lornejad-Schäfer Mohammad Reza,
Albrecht Ute,
Poppek Diana,
Gehrmann Thor,
Grune Tilman,
Bode Johannes G.,
Häussinger Dieter,
Schliess Freimut
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.09.053
Subject(s) - transactivation , stat protein , stat3 , phosphorylation , osmotic concentration , chemistry , ubiquitin , microbiology and biotechnology , proteasome , stat , immunoprecipitation , transcription factor , biology , biochemistry , gene
Little is known about the regulation of signal transducer and activator of transcription (STAT) stability. Here the osmolarity‐dependence of STAT3 stability, ubiquitination, Tyr 705 phosphorylation, STAT3 transactivation and γ‐fibrinogen (γ‐FBG) expression was studied in hepatoma cells. Hyper‐osmolarity accelerated STAT3 degradation which was prevented by proteasome inhibitors. Hypo‐osmolarity stabilized STAT3, most likely due to a decrease in STAT3 ubiquitination. Accordingly, STAT3 Tyr 705 phosphorylation, α 2 ‐macroglobulin promoter activity and γ‐FBG expression were osmosensitive. Modulation of STAT3 stability may contribute to a hydration dependence of acute phase protein expression.