Whole organism and tissue specific analysis of pexophagy in Drosophila

Peroxisomes are essential organelles involved in critical metabolic processes in animals such as fatty acid oxidation, ether phospholipid production and reactive oxygen species detoxification. We have generated transgenic Drosophila melanogaster models expressing fluorescent reporters for the selective autophagy of peroxisomes, a process known as pexophagy. Using light sheet microscopy, we have been able to obtain a global overview of pexophagy levels, across the entire organism at different stages of development. Tissue specific control of pexophagy is exemplified by areas of peroxisome abundance but minimal pexophagy observed in clusters of oenocytes, which are the major site of long chain fatty acid synthesis. They are surrounded by epithelial cells where pexophagy is much more evident. Enhancement of pexophagy was achieved by feeding flies with the iron chelator deferiprone, in line with past results using mammalian cells. Specific drivers were used to visualise pexophagy in neurons, in which we tested the role of two proteins proposed to regulate pexophagy. Firstly, depletion of CG8814, the Drosophila homologue of the yeast protein Atg37, had no noticeable impact on pexophagy. In contrast, specific depletion in the larval central nervous system of Hsc70-5, the Drosophila homologue of the chaperone HSPA9/Mortalin, led to a substantial elevation in pexophagy.