Figure 7. Murine GPAT4 Localizes to LDs and Is Required for the Formation of Large LDs.

(A) Murine GPAT4-GFP (green) expressed in COS7 cells relocalizes from the ER to LDs (red) during incubation in oleate-containing medium. Scale bars, 10 μm (overview) and 1 μm (magnification).

(B) GPAT4 is required for formation of large LDs specifically under conditions of de novo TG synthesis. Fluorescence images of BODIPY-stained LDs in control of Gpat4^−/− BMDMs incubated with oleate or AcLDL-containing medium for 12 hr. Scale bars 10 μm (overview) and 1 μm (magnification). The distribution of diameters for 500 measured LDs from 25 different cells for control (red) or Gpat4^−/− (black) is shown. Histogram of LD sizes as in Figure 5A (parameters of Gaussians: a1, 109; b1, 0.4387; c1, 0.1438; a2, 79.14; b2, 0.7446; c2, 0.2606).

(C) GPAT4 and DGAT2 are required for large LDs in MEFs. Fluorescence images of BODIPY-stained LDs in control, Gpat4^−/−, Dgat2^−/−, and Dgat1^−/− MEFs incubated with oleate-containing medium for 12 hr. Scale bars, 10 μm (overview) and 2 μm (magnification). The distribution of diameters for 600 measured LDs from 30 different cells for control (red), Gpat4^−/− (black), Dgat2^−/− (dark green), or Dgat1^−/− (light green) is shown (parameters of Gaussians: a1, 85.24; b1, 0.5043; c1, 0.1654; a2, 21.95; b2, 1.067; c2, 0.4563). A TLC showing TG levels in MEFs of the different genotypes is shown.

(D) Overexpression of DGAT2 or DGAT1 in MEFs leads to large or small LDs, respectively. Scale bar, 10 μm. (parameters of Gaussians: a1, 161.2; b1, 0.5535; c1, 0.2082; a2, 28.87; b2, 1.654; c2, 1.073).

(E) Overexpression of DGAT2 or DGAT1 in murine intestine leads to accumulation of large or small LDs visualized by CARS microscopy, respectively, after an acute dietary lipid challenge (2 hr postgavage with 200 μl oil). Scale bar, 10 μm.

See also Movie S2.