title: Cocoa procyanidins attenuate 4-hydroxynonenal-induced apoptosis of PC12 cells by directly inhibiting mitogen-activated protein kinase kinase 4 activity.
abstract: Neurodegenerative disorders such as Alzheimer's disease (AD) are associated with oxidative stress, and it has been suggested that apoptosis is a crucial pathway in neuronal cell death in AD patients. 4-Hydroxynonenal (HNE), one of the aldehydic products of membrane lipid peroxidation, is reported to be elevated in the brains of AD patients and mediates the induction of neuronal apoptosis in the presence of oxidative stress. In this study, we investigated the HNE-induced apoptosis mechanism and the protective effects of the cocoa procyanidin fraction (CPF) and its major antioxidant procyanidin B2 against the apoptosis induced by HNE in rat pheochromocytoma (PC12) cells. HNE-induced nuclear condensation and increased sub-G1 fraction, both of which are markers of apoptotic cell death, were inhibited by CPF and procyanidin B2. Intracellular reactive oxygen species (ROS) accumulation was attenuated by pretreatment with CPF and procyanidin B2. CPF and procyanidin B2 also prevented HNE-induced poly(ADP-ribose) polymerase cleavage, antiapoptotic protein (Bcl-2 and Bcl-X(L)) down-regulation, and caspase-3 activation. Activation of c-Jun N-terminal protein kinase (JNK) and mitogen-activated protein kinase kinase 4 (MKK4) was attenuated by CPF and procyanidin B2. Moreover, CPF and procyanidin B2 bound directly to MKK4 and inhibited its activity. Data obtained with SP600125, a selective inhibitor of JNK, revealed that JNK is involved in HNE-induced apoptosis through the inhibition of PARP cleavage and caspase-3 activation in PC12 cells. Collectively, these results indicate that CPF and procyanidin B2 protect PC12 cells against HNE-induced apoptosis by blocking MKK4 activity as well as ROS accumulation.
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Republic of Korea.
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Cho
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Jang
authors.forename: Nam Joo
authors.initials: NJ
authors.lastname: Kang
authors.forename: Mun Kyung
authors.initials: MK
authors.lastname: Hwang
authors.forename: Yong Taek
authors.initials: YT
authors.lastname: Kim
authors.forename: Ki Won
authors.initials: KW
authors.lastname: Lee
authors.forename: Hyong Joo
authors.initials: HJ
authors.lastname: Lee
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D000544:Alzheimer Disease / Q000503:physiopathology; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis; D044946:Biflavonoids / Q000494:pharmacology*; D002099:Cacao; D053148:Caspase 3 / Q000378:metabolism; D002392:Catechin / Q000494:pharmacology*; D019610:Cytoprotection; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D018384:Oxidative Stress; D016716:PC12 Cells; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D044945:Proanthocyanidins / Q000494:pharmacology*; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000447:Aldehydes; D000873:Anthracenes; D044946:Biflavonoids; D044945:Proanthocyanidins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D051020:bcl-X Protein; C432165:pyrazolanthrone; C479580:procyanidin B2; D002392:Catechin; D011065:Poly(ADP-ribose) Polymerases; D048031:JNK Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D053148:Caspase 3; C027576:4-hydroxy-2-nonenal