Fig. 5.
ERα amplifies insulin synthesis through the Src/ERK pathway. (A and B) Inhibition of E2-induced preproinsulin expression (A) and rise in insulin concentration by ERK inhibition (B) in WT mice islets. Female mouse islets were treated with E2 (10−8 M) or PD98059 (10−5 M) for 48 h before measurement of preproinsulin expression and insulin concentration. (C) Suppression of insulin synthesis by siRNA of ERK1/2 in MIN6. Cells were transfected with ERK1/2 siRNA for 5 h at 37 °C. ERK1/2 expression (blot), preproinsulin mRNA (Left), and insulin concentration (Right) was determined by Western blot analysis, RT-PCR, and RIA, respectively, after E2 (10−8 M) treatment for 48 h. All blots shown are representative of triplicate experiments. (D) Immunoprecipitation of c-Src in MIN6 cells after E2 stimulation (10−8 M) at 0, 2, 5, 10, and 30 min. (E) Inhibition of E2-induced rise in islet insulin content by SU6656 in WT mice islets (n = 5–6/group). Results represent mean ± SEM. *P < 0.05; **P < 0.01.