The arouser EPS8L3 Gene Is Critical for Normal Memory in Drosophila

Abstract

The genetic mechanisms that influence memory formation and sensitivity to the effects of ethanol on behavior in Drosophila have some common elements. So far, these have centered on the cAMP/PKA signaling pathway, synapsin and fas2-dependent processes, pumilio-dependent regulators of translation, and a few other genes. However, there are several genes that are important for one or the other behaviors, suggesting that there is an incomplete overlap in the mechanisms that support memory and ethanol sensitive behaviors. The basis for this overlap is far from understood. We therefore examined memory in arouser (aru) mutant flies, which have recently been identified as having ethanol sensitivity deficits. The aru mutant flies showed memory deficits in both short-term place memory and olfactory memory tests. Flies with a revertant aru allele had wild-type levels of memory performance, arguing that the aru gene, encoding an EPS8L3 product, has a role in Drosophila memory formation. Furthermore, and interestingly, flies with the aru8–128 insertion allele had deficits in only one of two genetic backgrounds in place and olfactory memory tests. Flies with an aru imprecise excision allele had deficits in tests of olfactory memory. Quantitative measurements of aru EPS8L3 mRNA expression levels correlate decreased expression with deficits in olfactory memory while over expression is correlated with place memory deficits. Thus, mutations of the aru EPS8L3 gene interact with the alleles of a particular genetic background to regulate arouser expression and reveals a role of this gene in memory.

Sleep Restores Behavioral Plasticity to Drosophila Mutants

“…As seen in Figure 4G, RU-fed DaGSw/+>UAS-aru RNAi /+ flies displayed STM impairments compared to vehicle-fed siblings. These data provide a confirmation of the aru 8.128 /+ data shown in Figure 4F and are consistent with previous reports of STM deficits in aru mutants [62]. Since THIP-induced sleep did not alter DLG protein levels in dnc 1 mutants, we hypothesized that knocking down aru in the dnc 1 mutant background would not restore STM.…”

“…Are the changes in DLG protein levels associated with changes in STM? As seen in Figure 4F, both rut 2080 and aru 8.128 /+ mutants display impaired STM in the APS as expected [13, 16, 62]. In contrast, rut 2080 ;aru 8.128 /+ flies display STM.…”

“…If THIP-induced sleep restores STM to rut 2080 mutants by increasing synapses, then it should be possible to use genetics to increase synapses and restore STM in a rutabaga mutant background without increasing sleep. The arouser mutant ( aru 8.128 ) is known to have an increased number of synaptic terminals in both the larva and adult fly and also display memory impairments [61, 62]. As seen in Figure 4E, both aru 8.128 /+ and rut 2080 ;aru 8.128 /+ flies show increased levels of DLG protein compared to rut 2080 controls.…”

Adipokines set neural tone by regulating synapse number

“…In C. elegans, Gel's actin-severing function has been shown to participate in synapse elimination under control of the cell death pathway (Meng 25 et al, 2015). Aru's regulation of synapse number in the Drosophila brain has been described (Eddison et al, 2011;LaFerriere et al, 2011); however, Aru has not heretofore been implicated in actin dynamics. And while Bsg has been previously shown to alter presynaptic actin organization such that synaptic vesicle compartmentalization and release are affected (Besse et al, 2007), our findings broaden Bsg's known actin-dependent activities to encompass determination of synapse number.…”

“…The aru 08696 , aru , and aru S13 mutant strains were provided by Ulrike Heberlein (Eddison et al, 2011;LaFerriere et al, 2011). UAS and LexAop lines: UAS-luc (Rajan and Perrimon, 2012); Synaptophysin-pHTomato provided by Andre Fiala (Pech et al, 2015); UAS-spGFP1-10 and LexAop-spGFP11 provided by Kristin Scott (Gordon and Scott, 2009); UAS-STAT92E ∆N∆C (CA) and UAS-STAT92E Y711F (DN) provided by Erika Bach (Ekas et al, 2010); Gad1-Ga80 provided by Toshihiro Kitamoto; and UAS-aru-myc (generated for this study).…”