Regulation of intramitochondrial cholesterol transfer to side-chain cleavage cytochrome P-450 in rat adrenal gland.
Regulation of intramitochondrial cholesterol transfer to side-chain cleavage cytochrome P-450 in rat adrenal gland.
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DOI：
10.1073/pnas.80.3.702
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发表时间：
1983-02
影响因子：
11.1
通讯作者：
C. Privalle;J. Crivello;C. Jefcoate
中科院分区：
文献类型：
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作者：
C. Privalle;J. Crivello;C. Jefcoate
当氨基戊硫胺抑制侧链切割时，大鼠肾上腺线粒体在体内醚应激期间积累胆固醇（对照组= 14.6对氨基戊硫胺= 26.5微克胆固醇/毫克蛋白质）。这种积累对同时给予环己亚胺（24.2微克/毫克）不敏感，但线粒体侧链切割大大减少。采用不连续菲科尔梯度离心法分离线粒体外、内膜组分。内膜、外膜和微粒体酶标记酶的定量分析表明，外膜中含有的内膜少于5%。内膜组分外膜含量低于7%，线粒体细胞色素P-450含量为90%。电镜显示外膜为圆形完整的鬼影，而内膜基本完整，保留完整肾上腺皮质线粒体典型的囊泡结构。氨酰亚胺使内膜胆固醇增加了2倍（9.4对20.1微克/毫克），但同时给予环己亚胺完全阻止了这种增加（10.9微克/毫克）。我们得出结论：(1)在氨基乙硫胺存在的情况下，应激刺激肾上腺线粒体内膜中胆固醇的积累；(2)将胆固醇从细胞膜外转移到细胞膜内需要一种环己亚胺敏感剂。
Rat adrenal mitochondria accumulated cholesterol during ether stress in vivo when side-chain cleavage was inhibited by aminoglutethimide (control = 14.6 vs. aminoglutethimide = 26.5 micrograms of cholesterol per mg of protein). This accumulation was insensitive to simultaneous administration of cycloheximide (24.2 micrograms/mg), but side chain cleavage in the mitochondria was greatly decreased. Outer and inner mitochondrial membrane fractions were separated by discontinuous Ficoll gradient centrifugation. Quantitation of marker enzymes for inner, outer, and microsomal enzymes indicated that outer membranes contained less than 5% inner membranes. The inner membrane fraction contained less than 7% outer membrane and included 90% of mitochondrial cytochrome P-450. Electron microscopy revealed outer membranes as circular intact ghosts, whereas inner membranes were largely intact and retained vesicular structure typical of intact adrenal cortex mitochondria. Administration of aminoglutethimide effected a 2-fold increase in inner membrane cholesterol (9.4 vs. 20.1 micrograms/mg) but simultaneous administration of cycloheximide completely blocked this increase (10.9 micrograms/mg). We conclude that: (i) in the presence of aminoglutethimide, stress stimulates accumulation of cholesterol in the inner membrane of adrenal mitochondria; and (ii) transfer of cholesterol from outer to inner membranes requires a cycloheximide-sensitive agent.