title: Signal transduction pathways involved in oxidative stress-induced intestinal epithelial cell apoptosis.
abstract: Necrotizing enterocolitis (NEC) is a devastating inflammatory condition of the gut that occurs in premature infants. Ischemia-reperfusion gut injury with production of reactive oxygen species (ROS) is thought to contribute to NEC; the exact cellular mechanisms involved are largely unknown. The purpose of this study was to determine the intracellular signaling transduction pathways involved in oxidative stress-induced intestinal epithelial cell apoptosis. H2O2 treatment resulted in rat intestinal epithelial cell apoptosis in a dose- and time-dependent manner; the caspase inhibitor, zVAD-fmk, blocked this response. Western blotting was performed to determine phosphorylation of kinases and ELISA was used to assess DNA fragmentation, as a measure of apoptosis. A rapid increase in phosphorylation of extracellular signal-related kinase (ERK)1/2, c-Jun N-terminal kinase (JNK)1/2, and Akt was noted. Inhibition of ERK and JNK decreased H2O2-induced apoptosis. Additionally, inhibition of protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3-K) attenuated and enhanced H2O2-mediated apoptosis and mitochondrial membrane potential decrease, respectively. Furthermore, activation of PKC reduced the Akt phosphorylation, whereas inhibition of PKC attenuated H2O2-mediated activation of caspase-3 and enhanced the H2O2-induced Akt phosphorylation. This study shows that activation of multiple signaling transduction pathways occurs during oxidative stress-induced intestinal epithelial cell injury. In contrast to ERK, JNK, and PKC, PI3-K/Akt may play an important role as a protective cellular signaling pathway during this process.
authors.affiliation: Department of Surgery, The University of Texas Medical Branch, Galveston 77555-0353, USA.
authors.forename: Yuning
authors.initials: Y
authors.lastname: Zhou
authors.forename: Qingding
authors.initials: Q
authors.lastname: Wang
authors.forename: B Mark
authors.initials: BM
authors.lastname: Evers
authors.forename: Dai H
authors.initials: DH
authors.lastname: Chung
mesh_terms: D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D004789:Enzyme Activation; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
chemical_list: D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt