Late endocytic trafficking is blocked by cholesterol accumulation
in CT60 CHO cells expressing SSD-NPC1-GFP. (A) Western
blot analysis with anti-GFP antibody of total solubilized protein from
SSD-NPC1-GFP-expressing WT CHO cells (Left) and
EGFP-expressing WT CHO cells (Right). The predicted
molecular mass of GFP (27 kDa) combined with glycosylated SSD-NPC1 (170
kDa) is comparable to the 200-kDa band (Left).
(B–E) CT 60 CHO cells expressing SSD-NPC1-GFP fail to
clear cholesterol. Seventy-two hours after transfection, cells were
fixed, stained, and labeled with filipin (B, blue) to
visualize cholesterol by confocal microscopy. SSD-NPC1-GFP
(C, green) was also detected by indirect
immunofluorescence (D, red). (E)
Cholesterol-laden lysosomes in an SSD-NPC1-GFP transfected CT60 CHO
cell are labeled by endocytic uptake of rhodamine-dextran. In this
merged image, SSD-NPC1-GFP (green) is present as rings at the periphery
of rhodamine-dextran (red) in the cholesterol-laden core of lysosomes.
B–E are confocal images. [Bar = 10 μm
(B–D) and 2 μm (E).]