PUFA inhibits and SFA activates RHBDL4-dependent SREBP-1c cleavage. A, B) Eight-week-old male WT and RHBDL4 KO mice were fed a WD for 14 days and treated with 5% EPA-E once the last day. A) Immunoblot analysis of indicated proteins in the membrane fraction and NE of pooled mouse livers (n = 2 per group). P, precursor; N, nuclear. Asterisk shows nonspecific bands. B) qRT-PCR analysis of lipogenic genes in mouse livers. Data represented as means ± SEM. Quantification was performed on 9–10 samples. *P < 0.05; **P < 0.01; ***P < 0.001. C–E) HEK293 cells were transfected with HSV-SREBP-1c and RHBDL4 expression plasmids. After 4 h, cells were incubated with 10% delipidated serum (DLS) containing the indicated concentration of each fatty acid for 20 h. Immunoblot analysis of the indicated proteins in CE and NE was performed. SREBP-1c cleavage by AA, EPA, and DHA (C), SREBP-1c cleavage by PA (D), and SREBP-1c cleavage by 100 μM PA and 10 μM EPA (E) are shown. P, precursor; N, nuclear.