Fig. 7.

cFOS mediates LIF repression of the GnRH gene. a LIF treatment of GT1–7 cells induces cFOS, but not OCT-1, demonstrated by Western blots of nuclear extracts. b Overexpression of cFOS, by co-transfection of cFOS expression vector, is sufficient to repress the GnRH E/P reporter. Asterisk indicates significant difference (p < 0.05) determined with the t test. c Transient transfections of reporters containing the mutations of the putative cFOS binding sites in GT1–7 cells demonstrate that the mutation of the cFOS binding site at −1,793 abolishes LIF repression of the GnRH E/P reporter, indicated by the pound sign #. d The same mutation was created in the GnRH E/RSVp reporter and also abrogates the repression by LIF. Statistical significance (p < 0.05), indicated by an asterisk, was determined with ANOVA followed by Tukey’s post hoc test. # indicates lack of repression.