Fig. 4.

Oleate treatment reverses SREBP-1 expression and maturation defects in SCD1-deficient HepG2 cells. HepG2 cells were transfected with negative control (Ctrl) or SCD1-targeting siRNA (siSCD1) and treated (or not) with 100 μM oleate. A: fatty acids were extracted and quantified using GC/MS, including the monounsaturated fatty acids (MUFA) palmitoleate and oleate and saturated fatty acids (SFA) palmitate and stearate. The results of 5 experiments are presented as means ± SE. B: SREBP-1 mRNA expression was analyzed by quantitative reverse-transcription-polymerase chain reaction (qPCR) relative to housekeeping gene HPRT1. C: SREBP-1 protein expression, for both precursor (pSREBP-1) and mature (mSREBP-1) forms, was analyzed by Western blotting. D: protein levels evaluated by densitometry were normalized against GAPDH, used to calculate the mature/total ratio, and presented relative to untreated negative control. Each histogram presents the means ± SE of 5 independent experiments. *P < 0.05, **P < 0.002, and ***P < 0.001.