(A) Genomic structure of mouse Tm6sf2 gene. The spacer region for TALEN is in blue. TALEN-based genome editing was used to introduce 1 bp deletion at the site 67 in exon 1, which results in an L23 frameshift (fs) mutation and premature translation termination that occurs in exon 2. (B-F) Thirteen-week-old male WT (Tm6sf+/+) and Tm6sf2 knockout (Tm6sf2-/-) mice (n = 3 per group) maintained on a chow diet were used. Mice were fasted for 4 h and sacrificed for various assays. (B) Representative blots showing the expression of APOB, TM6SF2, ERLIN1 and ERLIN2 in the livers of Tm6sf2+/+ and Tm6sf2-/- mice. Clathrin heavy chain (CHC) was used as a loading control. Asterisk indicates non-specific bands. (C) Body weight. (D) Serum total cholesterol (TC) and triglyceride (TG) levels. Data are presented as mean±SD. Student’s t-test. *P<0.05, **P<0.01, NS, no significance. (E) Cholesterol distribution in serum lipoprotein fractions determined by fast-performance liquid chromatography. (F) Oil Red O staining of liver sections from Tm6sf2+/+ and Tm6sf2-/- mice. Boxed areas are shown at a higher magnification on the right. Scale bars, 20 μm (main), 10 μm (inset).