Atg6/UVRAG/Vps34-Containing Lipid Kinase Complex Is Required for Receptor Downregulation through Endolysosomal Degradation and Epithelial Polarity during Drosophila Wing Development
Figure 4
Identification of the abnormal organelles of Atg6 RNAi cells. (a), (b) Immunogold labeling of Atg6 RNAi cells with anti-GFP antibody to detect Lamp1-GFP. MVBs, dMVBs, and MLBs were positive to Lamp1-GFP. (c) Enzymecitochemistry revealed small, dense acid phosphatase positive structures (open arrow) in wild type pupal wing cells. Based on the size and morphology, these structures were considered as primary lysosomes. All other organelles were devoid of reaction product. (d) Electron-lucent MVBs in Atg6 depleted cells never contained acid phosphatase reaction product but were often found in the vicinity of acid phosphatase positive primary lysosomes (open arrow). (e) A dense multivesicular body-like structure (dMVB) showing acid phosphatase reaction product in an Atg6 RNAi pupal wing cell. (f) A multilamellar body (MLB) in Atg6 depleted cell positive to acid phosphatase. (g), (h) DAB-staining of pupal wings expressing plasma membrane localized horseradish peroxidase enzyme (HRP-CD2). (g) In control cells plasma membrane showed a prominent DAB staining (arrowheads), just as organelles with plasma membrane origin, such as early endosomes (EE), multivesicular bodies (MVB), and secondary lysosomes (Ly) as well. (h) The accumulated organelles in Atg6 depleted cells: the multivesicular bodies (arrows) and multilamellar bodies (open arrows) were all positive to DAB. M: mitochondria, MVB: multivesicular body, dMVB: dense multivesicular body-like structure, MLB: multilamellar body, N: nucleus, Ns: nucleolus, and Ly: lysosome. For genotypes, see Table S4. Scale bars represent 200 nm in (a)–(f) and 500 nm in (g), (h).
