Figure 2.

Selective disruption of mGlu5-Homer leads to constitutive mGlu5-driven signaling to ERK, translation initiation factors, and protein synthesis rates. A, Acute hippocampal slices from mGlu5^R/R mice display elevated protein synthesis rates compared with WT littermates as measured by incorporation of ³⁵S Met/Cys into total protein. Pretreatment with MPEP (10 μm), an mGlu5 NAM, equalizes protein synthesis rates between WT and mGlu5^R/R slices (n = 14 slices/condition from 7 mice/genotype). B, In a separate set of experiments, inhibition of the MEK with U0126 (10 μm) rescues protein synthesis rates in mGlu5^R/R slices to WT levels (n = 6 slices/condition from 3 mice/genotype). C, D, Representative Western blots and quantified group data reveal enhanced level translation initiation complexes in mGlu5^R/R hippocampal slices, as measured by coimmunoprecipitation of eIF4E with eIF4G that are rescued by pretreatment with MPEP (n = 4 mice/genotype). E, F, Representative Western blots and quantified group data demonstrate elevated phosphorylation of translation initiation factors downstream of ERK (Mnk1; 4EBP, S65; eIF4E) in acute hippocampal slices of mGlu5^R/R mice that are rescued by pretreatment with MPEP. P-ERK levels are unchanged in mGlu5^R/R slices and unaffected by MPEP (n = 4 mice/genotype). G, Western blots of fresh hippocampal lysates from WT and mGlu5^R/R littermates demonstrate elevated P-4EBP (S65) and P-eIF4E, but not P-ERK in vivo (n = 5–7 mice per genotype; one-sample t test). A–F, Two-way ANOVA; Sidak's post hoc tests. *p < 0.05. **p < 0.01. ***p < 0.001.