Article Figures & Data
Figures
- Figure 1.
I-2 negatively regulates memory formation in mice. A, Schematic of I-2 gene trapping. A large DNA cassette was inserted in the first intron of the mouse I-2 gene. B, Genotyping of I-2 mice. C, Western blotting confirmation of absence of I-2 protein in I-2 KO mice (E10.5) (I-2−/− mice die as embryos). D, I-2+/− mice (>2.5 months old) exhibit increased preference for a novel object compared with their wild-type littermates in a novel object recognition test 24 and 48 h after training. *p < 0.05, 2-tailed t test. E, I-2+/− mice exhibit increased freezing compared with their wild-type littermates in a CFC test. *p < 0.05, 2-tailed t test.
- Figure 2.
I-2 negatively regulates hippocampus-dependent memory formation in rats. A, Rats infused with lenti-I-2-shRNA demonstrated learning during place training (p = 0.004), whereas controls did not (p = 0.642). B, Rats infused with lenti-I-2-shRNA spent significantly more time in the target quadrant containing the hidden platform than controls during the two probes, which were at the end of days 2 and 4 (p = 0.02). C, Rats infused with lenti-I-2-shRNA demonstrated significantly more freezing than controls in a CFC test; p = 0.03; lenti-I-2-shRNA = 5, control = surgical shams (2) + lenti-GFP (3).
- Figure 3.
I-2 regulation of CREB-dependent gene expression. A, Increase of pCREB in the brains of I-2 heterozygous mice (2.5 months old, n = 5 for each group, p < 0.05, 2-tailed t test). B, I-2 KD leads to increased pCREB in cortical neurons (21 d in vitro, n = 3 for each group, p < 0.05, t test). C1, I-2 KD leads to increased expression of BDNF, c-fos, Egr1, and Homer1a genes. C2, qRT-PCR demonstration of successful I-2 knock-down. *p < 0.05, **p < 0.01, 2-tailed t test.
- Figure 4.
Characterization of I-2 regulation of PP1. A, PP1 inhibitory phosphorylation at T320 is significantly increased in I-2 homozygous mice (n = 3 for WT, n = 2 for I-2 homozygous mice, PP1pT320/PP1 = 3.5 that of WT; t test, p < 0.01). B, Decreased PP1 activity in 3-month-old I-2 heterozygote mouse brains (n = 5) relative to their WT littermates (n = 6) (t test: p < 0.01). Middle and right, No change in PP1 level in I-2 heterozygous mice brain (tissues are from same set of mice brains used in PP1 activity assay). C, Comparable PP1 activity is observed in I-2 or PP1 immunoprecipitates obtained from ∼4-week-old primary cortical neurons (n = 4 for each IP pair, p = 0.78.). ns, Not significant.
