Host lipid droplets: An important source of lipids salvaged by the intracellular parasite Toxoplasma gondii
Fig 2
Influence of Toxoplasma infection on host LD distribution.
A. Fluorescence microscopy of HFF infected with RFP-expressing Toxoplasma or WT for 24 h. Host LD were identified by staining with BODIPY 493/503 (green) and 4-,6-diamidino-2-phenylindole (DAPI, blue, nucleus). Uninfected and infected cells were incubated either under control conditions (corresponding to culture medium supplemented with 10% FBS that contains on average 3 μg/ml OA; in I) or with 0.2 mM OA added to the medium (corresponding to a ~20-fold excess of OA; in II). Images show host LD gathering around each PV, which was more pronounced upon OA addition. Arrowheads pinpoint PV. B. Fluorescence microscopy of GFP-ADRP-expressing HeLa cells infected with Toxoplasma for 24 h. The PV (arrowheads) were immunostained for GRA7 (red) in cells incubated with (in I) or without OA (in II). GFP-labeled host LD encircle the PV. In blue, DAPI. C. EM of HFF infected with Toxoplasma for 24 h and incubated with 0.2 mM OA during infection, confirming the amassing of host LD at the PV membrane (PVM). Host ER (hER) and mitochondria (hmt) remained associated with the vacuolar membrane (inset). Scale bar, 1 μm. D. Quantification of the percent of the PV population surrounded by host LD during infection, with or without exogenous 0.2 mM OA. GFP-ADRP-expressing HeLa cells were infected with Toxoplasma at the indicated times. PV were scored as LD-associated if > 70% of the total host LD population was grouped around the PV.