Figure 4.

Activation of hypoxia signaling induces autophagy in Drosophila. A-C) Overexpression of the Drosophila HIF-1α ortholog sima (A) or depletion of Vhl(B) induces the formation of autolysosomes positive for both Lamp1-GFP and LTR in fat body cell clones in well-fed larvae. Quantification of data is shown in panel C. Statistically significant differences are marked (u test, n = 6 per genotype, ** P < 0.01), and error bars denote standard error. D-F) Overexpression of sima (D) or knockdown of Vhl(E) promotes the formation of punctate mCherry-Atg8a in fat body cell clones marked by GFP-nls (nuclear localization sequence) in well-fed larvae. Quantification of data is shown in panel F. Statistically significant differences are marked (u test, n = 6 per genotype, ** P < 0.01), and error bars denote standard error. G-J) Overexpression of sima (G) or depletion of Vhl(H) leads to formation of dots that are mostly positive for mCherry with the mCherry-GFP-Atg8a reporter. Chloroquine treatment blocks the autolysosomal quenching of GFP, as puncta are now positive for both mCherry and GFP in cells overexpressing sima (I) or Vhl RNAi (J). K) Quantification of data from panels G-J. Statistically significant differences are marked (u or t test, n = 5-8 per genotype, ** P < 0.01, * P < 0.05), and error bars denote standard error. L) RT-PCR analyses show that the transcription of BNIP3 is upregulated in both Vhl and Rpn2 RNAi samples relative to controls. Boxed areas in A, B, D, E, G-J are shown enlarged. Scale bar in A equals 20 μm for A, B, D, E, G-J.

Lőw et al. BMC Cell Biology 2013 14:29   doi:10.1186/1471-2121-14-29
Download authors' original image