title: Hydrogen peroxide-induced neuronal apoptosis is associated with inhibition of protein phosphatase 2A and 5, leading to activation of MAPK pathway.
abstract: Oxidative stress-induced neuronal apoptosis is a prominent feature found in neurodegenerative disorders. However, how oxidative stress induces neuronal apoptosis is not well understood. To address this question, undifferentiated and differentiated neuronal cell lines (PC12 and SH-SY5Y) were exposed to hydrogen peroxide (H(2)O(2)), a major oxidant generated when oxidative stress occurs. We observed that H(2)O(2) induced generation of reactive oxygen species (ROS), leading to apoptosis of the cells in a concentration- and time-dependent manner. H(2)O(2) rapidly activated the mitogen-activated protein kinases (MAPK) including extracellular signal-regulated kinase 1/2 (Erk1/2), c-Jun N-terminal kinase (JNK) and p38. Inhibition of Erk1/2, JNK or p38 with kinase inhibitors (U0126, SP600125 or PD169316, respectively), downregulation of Erk1/2 or p38 using RNA interference, or expression of dominant negative c-Jun partially prevented H(2)O(2)-induced apoptosis. Pretreatment with N-acetyl-L-cysteine (NAC) scavenged H(2)O(2)-induced ROS, blocking activation of MAPKs and cell death. Furthermore, we found that H(2)O(2)-induced ROS inhibited serine/threonine protein phosphatases 2A (PP2A) and 5 (PP5), which was abrogated by NAC. Overexpression of PP2A or PP5 partially prevented H(2)O(2)-activation of Erk/12, JNK and p38, as well as cell death. Similar results were observed in primary murine neurons as well. The results suggest that H(2)O(2)-induction of ROS inhibit PP2A and PP5, leading to activation of Erk1/2, JNK and p38 pathways thereby resulting in neuronal apoptosis. Our findings suggest that inhibitors of MAPKs (JNK, Erk1/2 and p38), activators of phosphatases (PP2A and PP5) or antioxidants may have potentials to prevent and treat oxidative stress-induced neurodegenerative diseases.
authors.affiliation: Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
authors.forename: Long
authors.initials: L
authors.lastname: Chen
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Yin
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.forename: Shile
authors.initials: S
authors.lastname: Huang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D016716:PC12 Cells; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011247:Pregnancy; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; C089641:protein phosphatase 5