PKD prevents H2O2-induced apoptosis via NF-kappaB and p38 MAPK in RIE-1 cells.

Previously, we demonstrated that protein kinase D (PKD) plays a protective role during H(2)O(2)-induced intestinal cell death. Here, we sought to determine whether this effect is mediated by nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein kinases (MAPKs). Treatment with H(2)O(2) activated NF-kappaB in RIE-1 cells; H(2)O(2) also induced the translocation of NF-kappaB p65 as well as phosphorylation of IkappaB-alpha. PKD1 siRNA inhibited H(2)O(2)-induced activation, translocation of NF-kappaB, and phosphorylation of IkappaB-alpha. We also found that overexpression of wild type PKD1 attenuated H(2)O(2)-induced phosphorylation of p38 MAPK and its upstream activator, MAPK kinase (MKK) 3/6, whereas the phosphorylation was increased by PKD1 siRNA or kinase-dead PKD1. Phosphorylation of neither extracellular signal-regulated kinases (ERK) 1/2 nor c-Jun N-terminal kinases (JNK) was altered by PKD1 plasmids or siRNA. Our findings suggest that PKD protects intestinal cells through up-regulation of NF-kappaB and down-regulation of p38 MAPK.