Autophagy Stimulus Promotes Early HuR Protein Activation and p62/SQSTM1 Protein Synthesis in ARPE-19 Cells by Triggering Erk1/2, p38^MAPK, and JNK Kinase Pathways

Figure 4

Effects of Erk1/2 and AMPK inhibitors on HuR translocation, its phosphorylation, and p62 expression. Representative Western blotting (upper) and densitometric analysis (lower) of levels of HuR (a, d), phospho-HuR (p-HuR, in threonine residues) (b, e), and p62 (c, f), in the cytoplasm of ARPE-19 cells exposed to either solvent or AICAR + MG132 (A + M) for 2 hrs, in the presence or not of Erk1/2 inhibitor (50 μM PD98059) (a–c) or AMPK inhibitor (5 μM compound C (CC)) (d–f). Optical densities of HuR, phospho-HuR (p-HuR, in threonine residues), and p62 bands were normalized to α-tubulin, and the results expressed as mean percentages + S.E.M. (; , , and ; Tukey’s multiple comparison test).

(a)

(b)

(c)

(d)

(e)

(f)