Figure 4

Erk1/2 activation is inversely correlated with P75^NTR expression. (A, B) Immunohistochemistry on E12 dissociated ventral midbrain cultures derived from En^HTE12 embryos stained against TH (green) and P75^NTR. P75^NTR expression is absent in cultures treated with Penetratin-coupled double-stranded RNA oligos. (C) Western blot of ventral midbrain cultures using two methods of RNA transfection with different efficiencies: HiPerfect (HiP) and Penetratin-coupled RNA oligos show increase in phosphorylated Erk1/2 after silencing of P75^NTR, but no changes in phosphorylation of P38. (D) Quantification of P75^NTR expression and Erk1/2 phosphorylation after transfection with P75^NTR double-stranded RNA oligonucleotides, normalized against untreated En^HTcultures, showing the inverse correlation between the two parameters. Scale bars: 25 μm. Error bars indicate standard error.