The Effect of a Dominant Inhibitory p53 Protein on Stress Responses Induced by Toxic and Non-Toxic Concentrations of Anisomycin in PC12 Cells

Anisomycin, a ribotoxic compound, is an efficient inhibitor of eukaryotic translation: at toxic concentrations it interferes with the function of ribosomal peptidyl transferase, blocks protein synthesis and ultimately leads to apoptosis. The process is accompanied by the activation of various cellular stress mechanisms. Subinhibitory anysomycin concentrations, in contrast, do not inhibit translation and cause apoptosis, but still activate certain stress pathways. The aim of the present study was to compare the signaling effects of toxic (1µg/ml) and non-toxic (10ng/ml) anisomycin treatment in PC12 cells. In addition, the role of the p53 tumor suppressor protein in these processes was explored, using a PC12 cell line expressing a dominant inhibitory p53 protein. Apoptosis-mediating events (PKR cleavage, eIF2α phosphorylation, activation of caspase 3, 8 and 9 enzymes) were caused by high, but not low, anisomycin concentration in a p53-dependent manner. MAPK pathways (JNK, p38 MAPK, ERK) were stimulated by non-toxic anisomycin treatment, with a more complex p53 involvement. The apoptotic response of cells appeared to be supported by exosomal paracrine signaling.