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. 2019 Jun 13;8:e45631. doi: 10.7554/eLife.45631

Figure 4. Overexpression of Vps8 impairs lysosome and LRO formation.

(A and B) The size of lysosomes (marked by dLamp-3xmCherry) decreases, but their number increases in GFP marked starved fat cells overexpressing Vps8 (A) or vps39 RNAi compared to neighboring GFP-negative control cells. (C and D) Starved, GFP+ fat cells that are overexpressing Vps8 (C) or vps39 RNAi (D) are full of small Rab7+ vesicles, while the surrounding control cells contain fewer Rab7+ dots. (E) Developmental autophagy proceeds normally in a control fat cell (left) of a wandering staged larva, indicated by the presence of large lysosomes containing electron-dense, protein-rich material (Ly). In contrast, the Vps8 overexpressing cell (right) is devoid of such structures and is filled with double-membrane autophagosomes and small lysosomes. ER: endoplasmic reticulum. (F and G) Large 3xmCherry-Atg8a+ autolysosomes are absent from GFP marked Vps8 overexpressing cells compared to neighboring control cells (F), similar to vps39 RNAi cells (G) in the fat tissue of wandering larvae. (H) The bright red color of the compound eye of a control fly (left) becomes darker upon eye specific overexpression of Vps8 (right). Note that Vps8 overexpression also eliminates the pseudopupil, which is seen as a dark spot in the middle of the control eye (left).

Figure 4.

Figure 4—figure supplement 1. Quantification of data from Figure 4, panels A–D, F and G.

Figure 4—figure supplement 1.

The median and the average of data are indicated as a horizontal black line and x within the boxes, respectively. Bars show the upper and lower quartiles, and significant differences are indicated in panels.
Figure 4—figure supplement 2. Vps8 (miniCORVET) is dispensable for lysosome formation in starved fat cells.

Figure 4—figure supplement 2.

The patterns of dLamp-3xmCherry reporter (A,B) or endogenous Rab7 staining (C,D) in GFP marked vps8 RNAi starved fat cells are similar to surrounding control cells. (A’–D’) Quantification of data from panels A–D. The median and the average of data are indicated as a horizontal black line and x within the boxes, respectively. Bars show the upper and lower quartiles, ns: not significant.