title: Sensitization of vascular smooth muscle cell to TNF-alpha-mediated death in the presence of palmitate.
abstract: Saturated free fatty acids (FFAs), including palmitate, can activate the intrinsic death pathway in cells. However, the relationship between FFAs and receptor-mediated death pathway is still unknown. In this study, we have investigated whether FFAs are able to trigger receptor-mediated death. In addition, to clarify the mechanisms responsible for the activation, we examined the biochemical changes in dying vascular smooth muscle cell (VSMC) and the effects of various molecules to the receptor-mediated VSMC death. Tumor necrosis factor (TNF)-alpha-mediated VSMC death occurred in the presence of sub-cytotoxic concentration of palmitate as determined by assessing viability and DNA degradation, while the cytokine did not influence VSMC viability in the presence of oleate. The VSMC death was inhibited by the gene transfer of a dominant-negative Fas-associated death domain-containing protein and the baculovirus p35, but not by the bcl-xL or the c-Jun N-terminal kinase (JNK) binding domain of JNK-interacting protein-1, in tests utilizing recombinant adenoviruses. The VSMC death was also inhibited by a neutralizing anti-TNF receptor 1 antibody, the caspase inhibitor z-VAD, and the cathepsin B inhibitor CA074, a finding indicative of the role of both caspases and cathepsin B in this process. Consistent with this finding, caspase-3 activation and an increase in cytosolic cathepsin B activity were detected in the dying VSMC. Palmitate inhibited an increase of TNF-alpha-mediated nuclear factor kappa B (NF-kappaB) activity, the survival pathway activated by the cytokine, by hindering the translocation of the NF-kappaB subunit of p65 from the cytosol into the nucleus. The gene transfer of inhibitor of NF-kappaB predisposed VSMC to palmitate-induced cell death. To the best of our knowledge, this study is the first report to demonstrate the activation of TNF-alpha-mediated cell death in the presence of palmitate. The current study proposes that FFAs would take part in deleterious vascular consequences of such patients with elevated levels of FFAs as diabetics and obese individuals via the triggering of receptor-mediated death pathways of VSMC.
authors.affiliation: Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejon, Republic of Korea.
authors.forename: Mun-Chual
authors.initials: MC
authors.lastname: Rho
authors.forename: Kyeong
authors.initials: K
authors.lastname: Ah Lee
authors.forename: Sun
authors.initials: S
authors.lastname: Mi Kim
authors.forename: Chang
authors.initials: C
authors.lastname: Sik Lee
authors.forename: Min
authors.initials: M
authors.lastname: Jeong Jang
authors.forename: Young
authors.initials: Y
authors.lastname: Kook Kim
authors.forename: Hyun
authors.initials: H
authors.lastname: Sun Lee
authors.forename: Yung
authors.initials: Y
authors.lastname: Hyun Choi
authors.forename: Byung
authors.initials: B
authors.lastname: Yong Rhim
authors.forename: Koanhoi
authors.initials: K
authors.lastname: Kim
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D053200:Fas-Associated Death Domain Protein / Q000235:genetics / Q000378:metabolism; D055436:Growth Differentiation Factor 15; D006801:Humans; D007097:Imines / Q000494:pharmacology; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010168:Palmitates / Q000494:pharmacology*; D011095:Polyethylenes / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000276:immunology / Q000378:metabolism; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000906:Antibodies; D051017:Apoptosis Regulatory Proteins; D016207:Cytokines; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; C526140:GDF15 protein, human; C526142:Gdf15 protein, rat; D055436:Growth Differentiation Factor 15; D007097:Imines; D051034:Inhibitor of Apoptosis Proteins; D016328:NF-kappa B; D010168:Palmitates; D011095:Polyethylenes; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; C505405:poly(ethylene imine); D008156:Luciferases; D048031:JNK Mitogen-Activated Protein Kinases; D053148:Caspase 3; D002401:Cathepsin B