Fig. 8: Activation of glycolysis contributes to Aub function in GSC self-renewal.

a–c Confocal images of immunostaining of aub^QC42/HN2; nos-Gal4/+ (a, b) and aub^QC42/HN2Pfk^EY23126/+; nos-Gal4/+ (c) germaria with anti-Vasa (green), anti-Hts (red) and DAPI (blue). The yellow dashed lines indicate the GSCs. An empty germarium, devoid of germ cells is shown in (b). d Quantification of germaria showing GSC loss (0–1 GSC) in mutant females of the indicated genotypes, 7 and 14 days after eclosion, and of empty germaria in mutant females 14 days after eclosion. The number of scored germaria (n) is indicated. **p-value < 0.01, ****p-value < 0.0001, ns, non-significant using the χ² test. For GSC loss at 7 days, p = 1.0e−6 between aub^QC42/HN2; nos-Gal4/+ and aub^QC42/HN2 Pfk^EY23126/+; nos-Gal4/+; 0.0019 between aub^QC42/g1; nos-Gal4/+ and aub^QC42/g1 Pfk^EY23126/+; nos-Gal4/+. For GSC loss at 14 days, p = 6.56e−5 between aub^QC42/HN2; nos-Gal4/+ and aub^QC42/HN2 Pfk^EY23126/+; nos-Gal4/+; 0.08 between aub^QC42/g1; nos-Gal4/+ and aub^QC42/g1 Pfk^EY23126/+; nos-Gal4/+. For empty gemaria, p = 8.72e−6 between aub^QC42/HN2; nos-Gal4/+ and aub^QC42/HN2 Pfk^EY23126/+; nos-Gal4/+; 1.37e-8 between aub^QC42/g1; nos-Gal4/+ and aub^QC42/g1 Pfk^EY23126/+; nos-Gal4/+. e Model of Aub and piRNA function in metabolic remodeling in GSCs. Aub guided by piRNAs binds glycolytic mRNAs in GSCs leading to their translational activation and higher levels of glycolytic enzymes. Translational activation might involve Aub interaction with the translation initiation factors PABP and eIF3 as is the case in the embryo⁵⁴. Aub-dependent activation of glycolytic mRNAs leads to high glycolysis in GSCs that is required for their self-renewal. During cyst cell differentiation, mitochondrial maturation takes place leading to an increased number of fused mitochondria equipped with cristae. This allows a gradual metabolic rewiring towards oxphos during the process of germ cell differentiation. Other factors (question mark) are expected to cooperate with Aub to restrict translational activation to GSCs. Scale bars: 10 μm. Source data are provided as a Source Data file. Panel e was created with BioRender.com released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/deed.en).