Figure 7.

The MAPK proteins ERK-1 and ERK-2 are essential for the autophagy-induced upregulation of occludin. [A] STRING analysis of the Caco-2 protein interactome shows crossover between MAPK proteins ERK1/2, occludin, caveolin-1 and the autophagy cluster. [B] ERK1/2 phosphorylation increased after starvation. [C] Quantification of phospho-ERK1/2 levels in panel B. Blot and densitometric quantification from three independent experiments. [D] Inhibition of ERK1/2 activation with U0126 [25 µM] or PD98059 [20 µM] prevented the starvation-induced reduction in inulin flux. Data represent three independent experiments. [E] Efficacy of CRISPR/Cas9-mediated knockout of the ERK-1 and ERK-2 in Caco-2 [dKO] cells. [F] Starvation increased the TER of both Scr and dKO Caco-2 cell monolayers, but did not change the inulin flux in ERK deficient dKO cells [G]. Data from six independent experiments. One-way ANOVA with Tukey’s post-hoc test. *, ^# and **, p < 0.05.