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. 2009 Apr 1;20(7):2004–2014. doi: 10.1091/mbc.E08-12-1250

Figure 5.

Figure 5.

Inhibition of autophagy by Atg13 overexpression. All panels depict fat body tissues from 4-h starved animals, unless otherwise indicated. (A and B) Starvation induces induction of mCherry-Atg8a–positive autophagosomes in controls (A) but not in animals overexpressing Atg13 (B). (C) Clonal expression of Atg13-GFP cell autonomously disrupts accumulation of LysoTracker Red—labeled autolysosomes. (D and E) Distribution of Atg13-GFP changes from a diffuse pattern under fed conditions (D) to small, uniform punctate structures after 4-h starvation (E). Atg13-GFP punctae (boxed area in E, enlarged in E′) are smaller than mCherry-Atg8a labeled autophagosomes and autolysosomes (boxed area in A, enlarged in A′). (F) In cells with high levels of Atg13-GFP expression, most Atg13-GFP–positive structures fail to label with mCherry-Atg8a. Yellow circles indicate examples of colocalization. (G) Atg13-GFP localizes to mCherry-Atg8a–labeled autophagosomes in cells with low levels of Myc-Atg1 and Atg13-GFP coexpression. Yellow circles indicate examples of colocalization. (H) Loss of Atg13 leads to increased levels of Myc-Atg1. A two-cell clone of Atg13 mutant cells (marked by lack of GFP) contains higher levels of Myc-Atg1 (red) than in neighboring control cells. (I and J) Starvation-induced Atg13-GFP redistribution is blocked by coexpression of Rheb (I) but is independent of Atg1 (J). Atg13-GFP is localized to punctate structures in both control cells and in cell clones homozygous mutant for Atg1 (central cell in J). Scalebar in A represents 10 μm in all panels, except A′ and E′ 5 μm, in C 38 μm, and in H 20 μm. Genotypes: (A) hsFLP/+; Act>CD2>GAL4 UAS-mCherry-Atg8a/+; (B–E) hsFLP/+; UAS-Atg13-GFP/+; Act>CD2>GAL4 UAS-mCherry-Atg8a/+; (F) UAS-Atg13-GFP/+; hsGAL4 UAS-mCherry-Atg8a/+; (G) UAS-Atg13-GFP/+; hsGAL4 UAS-mCherry-Atg8a/UAS-Myc-Atg1; (H) hsFLP/UAS-Myc-Atg1; Cg-GAL4/+; UAS-mCherry-Atg8a FRT82B UAS-GFPnls/FRT82B Atg13Δ74; (I) hsFLP/+; UAS-Atg13-GFP/+; Act>CD2>GAL4 UAS-GFPnls UAS-RhebAV4; and (J) hsFLP/+; UAS-Atg13-GFP/Cg-GAL4; FRT82B UAS-myrRFP/Atg1Δ3D FRT80B.