7-Ketocholesterol predisposes human aorta smooth muscle cells to Fas-mediated death.
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.
Rho
Mun-Chual
MC
Laboratory of Lipid Metabolism, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
Kim
Young Kook
YK
Chang
Jong Sun
JS
Lee
Hyun Sun
HS
Baek
Jin Ah
JA
Chung
Mi Yeon
MY
Lee
Han Cheol
HC
Lee
Hwan Woo
HW
Rhim
Byong Yong
BY
Reidy
Michael A
MA
Kim
Koanhoi
K
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*
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