Fig. 2

The inhibitory potential of SOCS3 does not depend on isoform-specific N-terminal peptide. a HEK293 cells were transfected with expression vectors for SOCS3 M12V or SOCS3 dN or empty vector (ctrl). Protein expression of SOCS3 isoforms and tubulin were monitored by Western blotting. Arrowheads indicate the long and short isoforms of SOCS3. b HEK293 FlpIn cells stably transfected to express doxycycline-dependently SOCS3 M12V or SOCS3 dN were treated for 16 h with the indicated amount of doxycycline to induce expression of SOCS3 isoforms and stimulated with hyIL-6 (20 ng/mL, 16 h) to induce IL-6-dependent STAT3-activation. STAT3 phosphorylation as well as STAT3, SOCS3 and tubulin protein expression were evaluated by Western blotting. Arrowheads indicate the long and short isoforms of SOCS3. Representative results of n = 3 independent experiments are shown. c Cells as in (B) were transfected with STAT3-reporter constructs and a β-galactosidase encoding expression vector. Cells were treated for 16 h with the indicated amount of doxycycline to induce SOCS3 isoform expression and with hyIL-6 (50 ng/mL, 16 h) to induce reporter gene expression. Luciferase activity was normalized to β-Galactosidase activity. Maximal reporter activity was set to 100%. Data are given as mean of three independent experiments ± SD. rANOVA: n.s. p > 0.05