Nedd4-2-dependent regulation of astrocytic Kir4.1 and Connexin43 controls neuronal network activity

Nedd4-2 is an E3 ubiquitin ligase in which missense mutation is related to familial epilepsy, indicating its critical role in regulating neuronal network activity. However, Nedd4-2 substrates involved in neuronal network function have yet to be identified. Using mouse lines lacking Nedd4-1 and Nedd4-2 and an isobaric labeling approach for quantitative comparison of the synaptic membrane proteome, we identified astrocytic channel proteins inwardly rectifying potassium channel 4.1 (Kir4.1) and Connexin43 as upregulated in ubiquitin ligase knockout mice and thus as candidate Nedd4-2 substrates. Kir4.1 and Connexin43 were confirmed as Nedd4-2 substrates by independent methods and their functional role in astrocytes as to modulation of neuronal network activity was established.