Drosophila WDFY3/ Bchs overexpression impairs neural function

Pathogenic variants in WDFY3, a gene encoding for an autophagy adaptor termed ALFY, are linked to neurodevelopmental delay and altered brain size in human probands. While the role of WDFY3 loss-of-function is extensively studied in neurons, little is known about the effects of WDFY3 upregulation in different cell types of the central nervous system (CNS). We show that overexpression of the Drosophila melanogaster WDFY3 ortholog, Bchs, in either glia or neurons impaired autophagy and locomotion. Bchs glial overexpression also increased VNC size and glial nuclei number significantly, whereas neuronal Bchs overexpression affected wing and thorax morphology. We identified 79 genes that were differentially expressed and overlapped in flies that overexpress Bchs in glial and neuronal cells, respectively. Additionally, upon neuronal Bchs overexpression differentially expressed genes clustered in gene ontology categories associated with autophagy and mitochondrial function. Our data indicate that glial as well as neuronal Bchs upregulation can have detrimental outcomes on neural function. Overall design: To understand which molecular pathways are affected by Bchs overexpression and how this impacts brain function, we performed RNA-seq on heads from adult flies (22-31 h after eclosion) overexpressing Bchs in glia (repo-Gal4/UAS-bchs::HA) or neurons (nSyb-Gal4/UAS-bchs::HA). We performed differential gene expression analysis comparing the Bchs overexpression condition to the respective Gal4- and UAS-controls.