Figure 5.

GRIP1 Is Required for ApoER2-Mediated AMPA Receptor Insertion

(A and B) GRIP1 is required for AMPA receptor membrane insertion mediated by ApoER2. GluR2 insertion was examined in GRIP1 knockout neurons upon Reelin stimulation. Staining of newly inserted GluR2 in wild-type (+/+) and GRIP1 knockout (GRIP1^−/−) dendrites (A). Statistical analysis of GluR2 fluorescence intensities (n = 3) (B).

(C) Hippocampal neurons generated from single-heterozygous ApoER2 (ApoER2^+/−) and GRIP1 (GRIP^+/−) embryos show normal levels of newly inserted GluR2 upon Reelin stimulation (n = 3–4).

(D and E) Functional interaction between ApoER2 and GRIP1 is necessary for new AMPA receptor insertion. ApoER2^+/−; GRIP1^+/− compound hippocampal neurons were subjected to AMPA receptor membrane insertion assays with Reelin stimulation. Microscopic images show newly inserted GluR2 after Reelin stimulation in wild-type (+/+) and ApoER2^+/−; GRIP1^+/− compound neurons (D). Quantification of relative fluorescence intensities of newly inserted GluR2 in wild-type and compound neurons (n = 3) (E).

Scale bars in (A) and (D) represent 5 μm. Bar graphs show mean ± SEM (shown as error bars). ^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001.