Elucidation of the Role of Peroxisome Homeostasis in Drosophila Embryogenesis.

Abstract

Peroxisomes are subcellular organelles that play a crucial role in metabolism, reactive oxygen species (ROS) detoxification, and cellular signaling. Embryogenesis requires the coordinated function of organelles and cytoskeleton to give rise to epithelial-like cells. Previous studies from the lab have highlighted the significance of appropriate morphology, distribution and function of mitochondria in the morphogenetic processes involved in cell formation during Drosophila embryogenesis. However, the role of peroxisomes, an organelle that interacts with mitochondria, in regulating the different steps of cell formation and remodeling remains to be elucidated. Our results show that peroxisomes accumulate apically similar to mitochondria with the progression of cellularization. In embryos depleted for Drp1 (dynamin-related protein 1), which is involved in mitochondrial and peroxisome fission in various systems, peroxisomes appear to be enlarged, predominantly showing a fused state and reduced number, suggesting a role for Drp1 in peroxisomal fission during Drosophila cellularization. Further, to shed light on the peroxisome formation in embryonic development, we employed RNAi to knock down various PEX proteins known to be involved in peroxisome biogenesis. Our results show the absence or reduction in the number of peroxisomes upon the knockdown of PEX13, PEX16, PEX19 and PEX3, indicating their role in peroxisome biogenesis in embryogenesis. We further tested the role of ROS in regulating the numbers of peroxisomes. Depletion of mitochondrially targeted SOD2 led to an increase in the numbers of peroxisomes and the suppression of the defects in peroxisomes number in Drp1SG; sod2i mutant. This indicates the peroxisome numbers are likely to respond to increased oxidative stress, aiding ROS removal.