Figure 4: ERK retrograde signalling controls PCAF activation.
From: PCAF-dependent epigenetic changes promote axonal regeneration in the central nervous system
(a,b) NGF stimulates pERK, PCAF and H3K9ac expressions in adult DRG cultures after 3-h treatment, which is abrogated by the ERK kinase inhibitor PD98059 (PD), ICC (a) and fold change analysis of intensity density (b). Scale bar, 20 μm, N=3 per group, performed in triplicate. (c,d) Nuclear PCAF immunoprecipitation from in vivo L4-L6 DRG 24 h following Sham or SNA reveals an increase in PCAF expression and threonine phosphorylation following SNA but not serine phosphorylation, immunoblot (c) and fold change of density analysis (d). N=5 per group, performed in triplicate. (e–i) In L4-L6 DRG, 24 h following SNA we observe an increase in pERK (e,f), PCAF (g,h) and H3K9ac (g,i) expression, which is significantly decreased by ERK inhibition with PD at the nerve stump. Insert shows high nuclear expression of PCAF and H3K9ac after SNA. Scale bars, 75 μm, N=3 per group, performed in triplicate. (j–l) PD also inhibits gene expression (Q-PCR, N=3 per group) (j) as well as H3K9ac (k) and PCAF (l) at the promoters of GAP-43, Galanin and BDNF 24 h following SNA (ChIPs). N=6 per group, performed in triplicate. Error bars, s.e. (b,f,h,i) P<0.0001, ANOVA, Bonferroni post hoc tests, **P<0.001 and ***P<0.001, (d,j–l) Student’s t-test, *P<0.05, **P<0.001 and ***P<0.001. Original immunoblot images are shown in Supplementary Fig. 12.
