Fig. 12

A model for Osi function. Comparison between fat body metabolism in a control and osi-depleted background. Depleted Osi/ETFRF1 levels are associated with activation of Etf/EtfQO, increasing electron flow to CoQ, with the consequent retrograde electron transfer, leading to an increase in ROS levels and unbalanced intermediate metabolites, which potentially alter the integrity and physical properties of all membranes. These changes in lipid droplet membrane would provide access to lipases, increasing lipid degradation and depleting general energy reserves, represented as a reduced lipid droplet size in the right panel. Eventually, this reduced lipid storage leads to a cell-autonomous decrease in cell size, altering the normal development and triggering a change from continuous feeding to an active food-seeking behavior even in the presence of nutritious sources. Thus, Osi links lipid catabolism to cell growth signaling essential during early development. A Downregulation of EtfQ0 rescues osi-related developmental phenotypes, albeit the animals do not reach adulthood. The experiment was repeated three times. A representative one is shown. B Downregulation of walrus, Drosophila’s equivalent to Etf subunit, rescues osi-related fat body phenotypes to a large degree. Animals become viable adults. Dots represent the percentage of survival. The total number of animals assessed is indicated. A one-way ANOVA with Bonferroni’s multiple comparisons was performed. Three independent experiments were performed. Different letters indicate significant differences, p<0.05; treatments sharing any letter are not statistically different. The total number of samples analyzed is listed below the corresponding panel. All datasets and statistical analysis on which the conclusions are based are included in Additional file 2