FIGURE 7:

Acute free cholesterol accumulation induces the association of LDs with the ER. (A, B) Huh7 cells were treated with 10 μg/ml F1394 for 6 h. Cells were then fixed and examined under an electron microscope as described in Materials and Methods. (B) Higher magnification image of a dashed square area in A. Black arrowheads indicate the cisterns of ER connected with LDs. Red arrowheads indicate the mitochondria connected with LDs. Bar, 1 μm. (C, D) Cells were treated as described and then fixed and doubly labeled with anti-PLIN2 (5 nm) and anti-ApoB antibodies (10 nm, black arrowheads) as described in Materials and Methods. Insets, enlarged image of dashed squares. Bar, 0.1 μm. (E–H) Huh7 cells were treated with 10 μg/ml F1394 for 24 h. Cells were then fixed and examined under electron microscope as described in Materials and Methods. Cells contain LDs with different electron densities (E). LDs were often connected (G). (F) Higher-magnification image from dashed square area in E. (H) Enlarged image of LD. Each LD was connected to bilayer membranes (black arrowheads in F and H) and surrounded by tiny vesicles (red arrows in F and H). Bars, 1 μm (E, G), 0.1 μm (F, H).