Activity-dependent endocytosis of Wingless regulates synaptic plasticity in the Drosophila visual system

Genetic Regulation of Central Synapse Formation and Organization in <em>Drosophila melanogaster</em>

“…With essential baseline data in hand, the field is ready to exploit the power of fly genetics to carry out forward genetic screens and RNA sequencing to identify novel synaptogenic pathways and regulatory strategies used by diverse sets of neurons to organize synapse location and three-dimensional structure. Small-scale candidate screens in the optic lobe (Kawamura et al, 2020;Sugie et al, 2015) and in mechanosensory neurons (Urwyler et al, 2019) have already demonstrated that imaging of synaptic organization by light microscopy can reliably identify mutant phenotypes with the advantage of a semi-high throughput genetic screen. Further, once candidate synaptogenic genes have been discovered, cell-type specific transcriptomic and proteomic assays can be used as complementary approaches to identify additional components of synaptogenic pathways (Davis et al, 2020).…”

“…Recent work identified Wnt signaling by the Drosophila Wnt1 homologue Wingless as a key mediator of visual synaptic plasticity, opening the door to mechanistic studies of synaptic remodeling postdevelopment. Components of the divergent canonical Wnt signaling pathway (Ciani et al, 2004;Miech et al, 2008;Salinas, 2007) are required for activity-dependent AZ remodeling in R8 photoreceptors (Kawamura et al, 2020;Sugie et al, 2015). In wild-type animals reared under LL conditions, prolonged light exposure leads to Wingless pathway inactivation through endocytosis and autophagic degradation of the Wingless ligand (Kawamura et al, 2020) and to a reduction in AZ numbers.…”

“…Components of the divergent canonical Wnt signaling pathway (Ciani et al, 2004;Miech et al, 2008;Salinas, 2007) are required for activity-dependent AZ remodeling in R8 photoreceptors (Kawamura et al, 2020;Sugie et al, 2015). In wild-type animals reared under LL conditions, prolonged light exposure leads to Wingless pathway inactivation through endocytosis and autophagic degradation of the Wingless ligand (Kawamura et al, 2020) and to a reduction in AZ numbers. Ectopic activation of the Wingless pathway on the other hand, also under LL conditions, prevents the activity-dependent reduction in AZs (Kawamura et al, 2020).…”

“…In wild-type animals reared under LL conditions, prolonged light exposure leads to Wingless pathway inactivation through endocytosis and autophagic degradation of the Wingless ligand (Kawamura et al, 2020) and to a reduction in AZ numbers. Ectopic activation of the Wingless pathway on the other hand, also under LL conditions, prevents the activity-dependent reduction in AZs (Kawamura et al, 2020). This highlights a role for Wingless signaling in the activity-dependent modulation of synaptic organization, but additional Wingless-dependent and Wingless-independent roles likely remain.…”

Broad Complex and Wing Development in Cockroaches

“…The question is whether the first or second wave of expression of these wing-related genes is related to the initiation of wing development. In this context, we must bear in mind that what we call "wingrelated genes" are highly pleiotropic, so that these genes also have functions other than promoting wing development; for example, all of them are also related to some aspect of neural development (Berndt et al, 2015;Corty et al, 2016;Gabilondo et al, 2018;Kawamura et al, 2021;Tidswell et al, 2021). Regarding nub, it has been described that, in the milkweed bug O. fasciatus, this gene contributes to antenna morphogenesis, labial patterning, the length of the femoral segment in legs, and the formation of a limbless abdomen (Hrycaj et al, 2008).…”