title: 7-Ketocholesterol predisposes human aorta smooth muscle cells to Fas-mediated death.
abstract: Human vascular smooth muscle cells (HVSMCs) are resistant to Fas-mediated death under normal physiological conditions. However, HVSMC death by activation of the receptor pathway was reported in the atherosclerotic lesions. In this study, we investigated whether 7-ketocholesterol, one of the major cholesterol oxides in the lesions, altered resistance of HVSMC to Fas-mediated death pathway. Cross-linking of Fas receptor with agonistic anti-Fas antibody (CH11) in the presence of 7-ketocholesterol induced death in human aorta smooth muscle cells (HAoSMC) as detected by morphology, viability, and DNA fragmentation. The agonistic anti-Fas antibody, however, did not induce death in the presence of 7alpha-hydroxycholesterol or cholesterol. The HAoSMC death was significantly inhibited by an antagonistic Fas receptor (FasR) antibody and by expression of dominant negative Fas-associated death domain containing protein (DN-FADD) using adenoviruses. Activation of caspase-3 was observed in HAoSMC destined to death. HAoSMC death was significantly inhibited by pharmacological caspase inhibitor, z-VAD and z-DEVD, and baculovirus caspase inhibitor p35. 7-Ketocholesterol impaired mitochondrial transmembrane potential and ATP production. Overexpression of bcl-xL also significantly inhibited HAoSMC death. In dying HAoSMC, bax was translocated from the cytosol to mitochondria and cytochrome c was released from mitochondria into the cytosol. This is the first report demonstrating implication of the oxysterol in Fas-mediated death pathway. The present study proposes that 7-ketocholesterol would contribute to loss of HVSMC in the atherosclerotic lesions by altering resistance to receptor-mediated death pathway.
authors.affiliation: Laboratory of Lipid Metabolism, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
authors.forename: Mun-Chual
authors.initials: MC
authors.lastname: Rho
authors.forename: Young Kook
authors.initials: YK
authors.lastname: Kim
authors.forename: Jong Sun
authors.initials: JS
authors.lastname: Chang
authors.forename: Hyun Sun
authors.initials: HS
authors.lastname: Lee
authors.forename: Jin Ah
authors.initials: JA
authors.lastname: Baek
authors.forename: Mi Yeon
authors.initials: MY
authors.lastname: Chung
authors.forename: Han Cheol
authors.initials: HC
authors.lastname: Lee
authors.forename: Hwan Woo
authors.initials: HW
authors.lastname: Lee
authors.forename: Byong Yong
authors.initials: BY
authors.lastname: Rhim
authors.forename: Michael A
authors.initials: MA
authors.lastname: Reidy
authors.forename: Koanhoi
authors.initials: K
authors.lastname: Kim
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D001011:Aorta / Q000166:cytology*; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D048430:Cell Shape; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D053200:Fas-Associated Death Domain Protein; D006801:Humans; D007653:Ketocholesterols / Q000494:pharmacology*; D008564:Membrane Potentials; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D021381:Protein Transport; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D007653:Ketocholesterols; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; D045304:Cytochromes c; D020169:Caspases