Figure 5.

Endogenous miR-592 regulates p75^NTR levels. a, The 3′UTR of p75^NTR has a conserved site for miR-592. Putative binding sites for miR-592 on the p75^NTR 3′UTR are shown, with complementary sites in capitals. b, Primary neurons were infected with lentiviral vectors expressing the antagomiR-592 or scramble and analyzed for p75^NTR levels after 4 d in vitro. Blocking the activity of endogenous miR-592 increases the levels of neuronal p75^NTR. c, Quantification of p75^NTR levels from b (n = 4; Student's t test). d, A temporal decrease in p75^NTR protein levels is seen in the mouse cortex. e, Quantification of p75^NTR levels from d (n = 3; ANOVA). f, Cortical p75^NTR mRNA decreases in the first 2 weeks postnatally. Subsequent decline in p75^NTR protein is not accompanied by a decrease in p75^NTR mRNA (n = 3; ANOVA). g, Quantitative real-time PCR shows that miR-592 levels inversely correlate with p75^NTR protein levels, with a robust increase in miR-592 seen in the adult mouse (P60) cortex. microRNA levels are normalized to endogenous small RNA control U6 (n = 3; ANOVA). h, miR-592 or a scramble control was cotransfected with plasmids containing psicheck-2 empty vector or psiCheck-2-p75^NTR-3′UTR. A decrease in luciferase activity indicative of binding of miR-592 to the p75^NTR UTR is seen. Mutations (M1, M2) of the miR-592-binding sites on the p75^NTR 3′UTR abolish the effects of miR-592 on luciferase levels. miR-592 does not affect the luciferase levels in the empty vector lacking the p75^NTR 3′UTR (n = 3). Student's t test was used to compare between scramble and miR-592 transfections. *p < 0.05; **p < 0.01. n.s., Not significant.