Rho Mun-Chual, Kim Young Kook, Chang Jong Sun, Lee Hyun Sun, Baek Jin Ah, Chung Mi Yeon, Lee Han Cheol, Lee Hwan Woo, Rhim Byong Yong, Reidy Michael A, Kim Koanhoi
Laboratory of Lipid Metabolism, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
J Mol Cell Cardiol. 2005 Nov;39(5):823-32. doi: 10.1016/j.yjmcc.2005.07.018. Epub 2005 Sep 29.
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.
在正常生理条件下，人血管平滑肌细胞（HVSMC）对Fas介导的死亡具有抗性。然而，据报道在动脉粥样硬化病变中，HVSMC可通过受体途径激活而死亡。在本研究中，我们调查了病变中主要的胆固醇氧化物之一7-酮胆固醇是否会改变HVSMC对Fas介导的死亡途径的抗性。通过形态学、活力和DNA片段化检测发现，在存在7-酮胆固醇的情况下，Fas受体与激动性抗Fas抗体（CH11）交联可诱导人主动脉平滑肌细胞（HAoSMC）死亡。然而，在存在7α-羟基胆固醇或胆固醇的情况下，激动性抗Fas抗体并未诱导细胞死亡。使用腺病毒表达显性负性含Fas相关死亡结构域蛋白（DN-FADD）以及拮抗Fas受体（FasR）抗体可显著抑制HAoSMC死亡。在注定死亡的HAoSMC中观察到了caspase-3的激活。药理学caspase抑制剂z-VAD和z-DEVD以及杆状病毒caspase抑制剂p35可显著抑制HAoSMC死亡。7-酮胆固醇损害线粒体跨膜电位和ATP生成。bcl-xL的过表达也可显著抑制HAoSMC死亡。在濒死的HAoSMC中，bax从胞质溶胶转移至线粒体，细胞色素c从线粒体释放至胞质溶胶。这是首份证明氧甾醇在Fas介导的死亡途径中作用的报告。本研究表明，7-酮胆固醇可能通过改变对受体介导的死亡途径的抗性，导致动脉粥样硬化病变中HVSMC的丢失。
