Figure 1.

Silencing p75^NTR prevents proNGF accumulation and restores NGF levels in rat retina. Rats received single intraocular injection of one of the following: pGFP plus scrambled shRNA (GFP+Scr), pGFP plus shRNA against p75^NTR (GFP+shRNA); pGFP-proNGF123, a cleavage-resistant form of proNGF plus scrambled shRNA (proNGF+Scr); pGFP-proNGF123 plus shRNA against p75^NTR (proNGF+shRNA). Retinas were lysed after 6 weeks. (a) Representative western blot image and (b,c) statistical analysis of total p75^NTR (75 kDa) and its intracellular domain (ICD, 25 kDa) normalized to actin. A 2 × 2 analysis showed a significant interaction between proNGF overexpression and silencing p75^NTR. Overexpression of proNGF induced expression of both total p75^NTR and p75^ICD compared with GFP. Silencing p75^NTR with shRNA prevented the increase in p75^NTR and p75^ICD expression in proNGF group but not in GFP group. n = 4–5 per group, *P < 0.05 versus other groups. (d) Representative western blot image and statistical analysis of proNGF expression normalized to actin showing significant increases in proNGF in proNGF overexpressing group that were mitigated by silencing p75^NTR compared with GFP controls. (e) Representative western blot images and statistical analysis of NGF expression normalized to actin. A 2 × 2 analysis showed a significant interaction between proNGF overexpression and silencing p75^NTR. ProNGF overexpression resulted in significant decreases in NGF levels compared with GFP. Silencing p75^NTR with shRNA significantly reduced NGF levels in GFP-controls and restored NGF levels in proNGF overexpressing retina. Results presented as mean ± SD. n = 4–5 per group. *P < 0.05 versus other groups.