, 2010). Intriguingly, the AP2 interaction site in the β1-3 subunits overlaps with the binding site for the vesicular ATPase and trafficking factor NSF (Figure 1C) (Goto et al., 2005). NSF interacts with phorbol ester-activated PKCɛ. Moreover, PKCɛ phosphorylates and activates the ATPase function of NSF. PKCɛ-mediated

phosphorylation of NSF induces its translocation to the plasma membrane and to synapses and concurrently reduces the cell surface expression of GABAARs (Chou et al., 2010). PKCɛ knockout mice are less anxious and produce lower levels of stress hormone than WT mice (Hodge et al., 2002), which is the opposite of the anxious-depressive-like phenotype of GABAAR γ2 subunit heterozygous mice and therefore consistent with increased functional expression of GABAARs (Crestani et al., 1999 and Luscher et al., 2011). Therefore, pharmacological Wnt mutation inhibitors of PKCɛ activity may have therapeutic potential for the treatment of neuropathological conditions that involve deficits

in GABAergic transmission. This NSF-dependent trafficking mechanism is reminiscent of aforementioned earlier experiments conducted in heterologous cells, showing phorbol ester-induced and PKC and clathrin-mediated endocytosis Cabozantinib research buy of GABAARs from the plasma membrane by a mechanism that is independent of GABAAR phosphorylation (Chapell et al., 1998 and Connolly et al., 1999). PKCɛ is one of seven PKC isozymes activated by phorbol esters. It therefore seems likely that PKCɛ contributes to phorbol ester-induced endocytosis of GABAARs. However, one might predict that PKCɛ and NSF-dependent endocytosis of GABAARs is counteracted by the aforementioned PKC-βII-mediated phosphorylation of β subunits, which limits endocytosis of GABAARs. Consistent with multiple PKC and PKA-regulated modes of GABAAR trafficking, these kinases can have cell-type-specific and functionally opposite

effects on mIPSC amplitudes in vivo (Poisbeau et al., 1999). A third interaction of GABAARs with AP2 involves a bipartite motif in the intracellular loop region of the γ2 subunit (Figure 1C). It consists Dipeptidyl peptidase of a 12 amino acid basic domain that is homologous to the AP2 binding site in β subunits and a more C-terminal γ2-specific YGYECL motif (Smith et al., 2008). These two domains interact cooperatively with separate domains in the μ2 subunit of AP2. The γ2-specific YGYECL motif is of particular interest as it exhibits high affinity for AP2 that is sensitive to phosphorylation at γ2 Tyr365/367 (Kittler et al., 2008). These residues are phosphorylated by Fyn and other Src kinase family members in vivo (Lu et al., 1999 and Jurd et al., 2010). A nonphosphorylated YGYECL peptide effectively competes with the AP2-γ2 subunit interaction, thereby increasing the GABAAR surface expression and mIPSC amplitude and showing that this site is constitutively phosphorylated in cultured neurons (Kittler et al., 2008).