title: p62 binding to protein kinase C ζ regulates tumor necrosis factor α-induced apoptotic pathway in endothelial cells.
abstract: OBJECTIVE
  Protein kinase C (PKC) ζ is a key pathological mediator of endothelial cell apoptosis. p62 is a scaffold protein that regulates several cell signaling pathways by binding to target proteins. Because PKCζ and p62 contain Phox/Bem1p (PB1) modules that mediate protein-protein interactions, we hypothesized that an interaction between p62 and PKCζ is required for tumor necrosis factor α-induced PKCζ signaling in endothelial cells.
  
  
  RESULTS
  In human umbilical vein endothelial cell, tumor necrosis factor α (10 ng/mL) enhanced the interaction between p62 and PKCζ. Transfection with p62 small interfering RNA reduced the activation of both PKCζ and its downstream targets JNK and caspase 3, suggesting that p62 is necessary for PKCζ signaling. Overexpression of only the PB1 domain of p62 inhibited p62-PKCζ interaction, showing that binding of these 2 proteins is mediated by their PB1 domains. Furthermore, overexpression of the p62 PB1 domain suppressed tumor necrosis factor α-induced PKCζ activation and subsequent activation of JNK and caspase 3. Finally, transfection of either p62 small interfering RNA or the PB1 domain of p62 inhibited human umbilical vein endothelial cell apoptosis.
  
  
  CONCLUSIONS
  Our results suggest a novel function of p62 that regulates the activity of PKCζ by binding to PKCζ, thereby activating the PKCζ-JNK-caspase 3 apoptotic pathway in endothelial cells.
authors.affiliation: Department of Medicine, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Geun-Young
authors.initials: GY
authors.lastname: Kim
authors.forename: Patrizia
authors.initials: P
authors.lastname: Nigro
authors.forename: Keigi
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Abe
authors.forename: Bradford C
authors.initials: BC
authors.lastname: Berk
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D000099221:Protein Kinase C zeta
chemical_list: D053148:Caspase 3; D048670:MAP Kinase Kinase 4; D011493:Protein Kinase C; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D000099221:Protein Kinase C zeta