Fig. 3: Catalase flies undergo an oxidising shift in global thiol redox state.
From: Enhancing autophagy by redox regulation extends lifespan in Drosophila
a Scheme showing the dual function of Atg4 in autophagy: (1) initial redox-independent cleavage of Atg8, to expose a C-terminal glycine residue enabling lipidation by PE (phosphatidyl-ethanolamine) via the E1-like enzyme Atg7 and the E2-like enzyme Atg3. The conjugated Atg8-PE is involved in autophagosome elongation/closure; (2) redox-dependent de-lipidation of Atg8-PE, allowing interaction and fusion of the autophagosome with the endosomal-lysosomal compartments, and recycling of cleaved Atg8. Oxidation of a redox-regulatory cysteine (C102 in Drosophila Atg4a) selectively inactivates the Atg8-PE de-conjugation activity of Atg4, promoting autophagosome biogenesis and therefore enhancing Atg4-mediated autophagy. b Redox proteomic (OxICAT) analysis of d7, d28 and d56 catalase over-expressing females (da-GAL4 > UAS-cat) compared to control (UAS-cat/+). Distribution of total cysteine residue oxidation levels, plotted as the proportion of the total number of peptides containing unique cysteine residues in each 5% quantile of percentage oxidation. Data are means ± SEM of n = 5 biological replicates. c, d Oxidation state of cysteine residues present, comparing control versus catalase over-expressor females at d7 (c) and d56 (d). Data points above the diagonal dotted line (slope = 1) indicate cysteine residues more oxidised upon catalase upregulation, with red symbols designating significance (p < 0.05), assessed by unpaired two-tailed Student’s t-test. The total number of unique Cys-containing peptides is indicated in black. e Levels of Nrf2 signalling inferred using a gstD-GFP reporter in da-GS > UAS-cat females treated ± RU for d7 and d28. Western blotting against GFP, catalase and actin, showing n = 2 biological replicates per condition. f Levels of total glutathione measured in d7 control (UAS-cat/+) and catalase over-expressor (da-GAL4 > UAS-cat) females. Data are means ± SEM of n = 6 biological replicates, each with n = 10 females per sample, analysed by unpaired two-tailed Student’s t-test (head+thorax, p = 0.0216; abdomens, p = 4.5 × 10−7). n/s, p > 0.05; *, p > 0.01; ***, p > 0.001. Source data are provided as a Source Data file.
