Fig. 6.

Depletion of JNK2 inhibits insulin-induced SREBP-1 cleavage processing and nuclear translocation. A: Western blot analysis of pre-SREBP-1 and n-SREBP-1 protein expression in cytoplasmic and nuclear extracts, respectively. Differentiated adipocytes were treated with control siRNA (siControl) or JNK2 siRNA (siJNK2) in maintenance medium for 7 days. Cells were then starved in serum/Dex/insulin-free maintenance medium for 16 h followed by stimulation with or without 100 nM insulin for 1 h. β-actin served as a loading control. An arrowhead indicates the 54 kDa isoform of JNK2. These experiments were performed three times and the results of one representative experiment are shown. The protein expression levels of n-SREBP-1 were normalized relative to β-actin protein expression and are shown as relative protein levels. Data are presented as means ± SEM of three independent experiments. **P < 0.01 versus siControl without insulin; ^##P < 0.01 versus siControl with insulin. B: Confocal immunofluorescence microscopy of adipocytes stained with SREBP-1 (green) and DAPI (blue). DIC, differential interference contrast. Scale bar, 30 μm.