title: Protein kinase C epsilon regulates tumor necrosis factor-alpha-induced stannin gene expression.
abstract: Stannin (Snn) is a highly conserved vertebrate protein that has been closely linked to trimethyltin (TMT) toxicity. We have previously demonstrated that Snn is required for TMT-induced cell death. Others have shown that TMT exposure results in tumor necrosis factor-alpha (TNFalpha) production and that TNFalpha treatment induces Snn gene expression in human umbilical vein endothelial cells (HUVECs). In this study, we investigated a signaling mechanism by which Snn gene expression is regulated by TMT and demonstrated that TNFalpha stimulates Snn gene expression in a protein kinase C epsilon-dependent manner in HUVECs in response to TMT exposure. Supporting this, we show that TMT-induced toxicity is significantly blocked by pretreatment with an anti-TNFalpha antibody in HUVECs. Using a quantitative real-time polymerase chain reaction assay, we also show that the level of Snn gene expression is significantly increased in HUVECs in response to either TMT or TNFalpha treatment. This TNFalpha-induced Snn gene expression is blocked when HUVECs were pretreated with bisindolylmaleimide I, an inhibitor of protein kinase C (PKC). In contrast, when HUVECs were treated with phorbol 12-myristate 13-acetate, a PKC activator, we observed a significant increase in Snn gene expression. Using isotype-specific siRNA against PKC, we further show that knockdown of PKC epsilon, but not PKC delta or PKC zeta, significantly blocked TNFalpha-induced Snn gene expression. Together, these results indicate that TNFalpha-induced, PKC epsilon-dependent Snn expression may be a critical factor in TMT-induced cytotoxicity.
authors.affiliation: Department of Pharmacology , Penn State College of Medicine, Hershey, PA 17033, USA.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Reese
authors.forename: Collin
authors.initials: C
authors.lastname: Davidson
authors.forename: Melvin L
authors.initials: ML
authors.lastname: Billingsley
authors.forename: Jong
authors.initials: J
authors.lastname: Yun
mesh_terms: D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018076:DNA, Complementary / Q000096:biosynthesis / Q000302:isolation & purification; D042783:Endothelial Cells / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D019169:Jurkat Cells; D009479:Neuropeptides / Q000096:biosynthesis* / Q000235:genetics*; D011493:Protein Kinase C / Q000502:physiology*; D051744:Protein Kinase C-epsilon; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D034741:RNA, Small Interfering / Q000096:biosynthesis / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014298:Trimethyltin Compounds / Q000633:toxicity; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D018076:DNA, Complementary; D009479:Neuropeptides; D034741:RNA, Small Interfering; D014298:Trimethyltin Compounds; D014409:Tumor Necrosis Factor-alpha; C046488:trimethyltin; C075692:stannin; D012313:RNA; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon