E. and U.H., unpublished data). Regardless, aru and both the PI3K/Akt and Egfr/Erk pathways are needed during development to establish normal ethanol sensitivity. Yet it is likely that they function in multiple processes taking place at more than a single developmental period. Clearly, aru (this work) and http://www.selleckchem.com/products/sch-900776.html PI3K ( Martín-Peña et al., 2006) affect both larval and adult nervous system development, as alteration of synapse number is evident upon their genetic manipulation. Of note, although a role for Erk in bouton growth at the larval NMJ has been described ( Koh et al.,

2002), its true function remains unclear ( Wairkar et al., 2009). Our genetic epistasis experiments between Erk, PI3K, and aru can be interpreted in various non-mutually exclusive ways. One interpretation is that aru function may be required earlier in development than either the Egfr/Erk or PI3K/Akt pathways, its absence thus precluding the normal execution of these pathways’ functions. An alternative interpretation is that aru functions downstream of the Egfr/Erk and PI3K/Akt pathways, but does so in different neurons/brain circuits (see below). With regard to intracellular mechanisms, although activation of the Egfr can stimulate the PI3K pathway (Engelman et al., 2006), we found that analogous panneuronal manipulations (i.e.,

activation or inhibition) of these two pathways lead to opposite effects on ethanol sensitivity. These observations suggest that, in this context, Cobimetinib mouse Egfr overexpression does not necessarily activate PI3K, and that Egfr/Erk and PI3K/Akt pathways predominantly function in different neurons/neural circuits. Indeed, Egfr overexpression in dopaminergic neurons, but not PDF neurons ( Corl et al., 2009), reduces ethanol GPX6 sensitivity. Conversely, PI3K overexpression in PDF, but not the dopaminergic neurons, enhances ethanol sensitivity (this work). aru is expressed in PDF neurons ( Kula-Eversole et al., 2010) and we show that its knockdown specifically in these neurons affects ethanol sensitivity. In contrast, aru knockdown in dopaminergic neurons was inconsequential. Thus, while aru is needed for the effects of panneuronal Egfr/Erk

overexpression/activation, it does not appear to be a target of this pathway in dopaminergic neurons or the insulin-producing cells, two loci where Egfr overexpression affects ethanol sensitivity ( Corl et al., 2009 and Corl et al., 2005). Therefore, the Egfr/Erk pathway probably activates aru in neurons we have yet to identify. In summary, given that Aru is an adaptor protein with the potential to interact with multiple partners, we hypothesize that Aru carries out two distinct functions mediated by two different pathways in separable neuroanatomical loci. As aru and the Egfr/Erk and PI3K/Akt pathways are quite ubiquitously expressed, it is likely that Aru binding partners are context dependent and that these partners contribute to the different aru-mediated mechanisms affecting ethanol sensitivity.