EVIDENCE THAT HYDROGEN-PEROXIDE BLOCKS HORMONE-SENSITIVE CHOLESTEROL TRANSPORT INTO MITOCHONDRIA OF RAT LUTEAL CELLS
EVIDENCE THAT HYDROGEN-PEROXIDE BLOCKS HORMONE-SENSITIVE CHOLESTEROL TRANSPORT INTO MITOCHONDRIA OF RAT LUTEAL CELLS
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DOI：
10.1210/endo-128-6-2958
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发表时间：
1991-06-01
期刊：
影响因子：
4.8
通讯作者：
ATEN, RF
中科院分区：
文献类型：
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作者：
BEHRMAN, HR;ATEN, RF
在黄体和颗粒细胞中，过氧化氢突然抑制受体结合促性腺激素对腺苷酸环化酶的激活，并阻断类固醇生成。 在本研究中，研究了cAMP后位点对类固醇生成抑制的过氧化物作用。 过氧化氢可抑制dibutyrl或8-溴-cAMP刺激的类固醇生成。 然而，cAMP依赖性蛋白激酶激活的胞质溶胶或完整的细胞不受过氧化物处理。 过氧化氢也不抑制胆固醇酯酶和酰基辅酶A：酰基转移酶的活性。 25-和22-羟基胆固醇分别使孕酮合成最大增加5- 50倍。 然而，与cAMP类似物和LH不同的是，这些细胞渗透性胆固醇类似物和α渗透性胆固醇类似物刺激的胰蛋白酶蛋白合成不受过氧化氢的抑制。 用氨基-谷氨酰亚胺治疗动物，在随后分离和清洗的黄体组织中产生类固醇生成胆固醇底物的显著蓄积和非依赖性类固醇生成的大幅增加。 在这个范例中，过氧化氢并没有抑制升高的基础孕酮合成黄体细胞产生的氨鲁米特在体内治疗，但LH刺激的类固醇被阻断。 然而，用过氧化氢处理黄体细胞抑制了离体线粒体中的双烯醇酮合成，这种作用部分被黄体细胞胞浆所逆转。 总之，虽然过氧化物抑制cAMP依赖性类固醇生成，但似乎并不抑制蛋白激酶活化或胆固醇从细胞内酯化储存中的动员。 尽管过氧化物抑制了阿替烯醇酮的合成，但当底物通过添加胆固醇类似物或预先用氨鲁米特在体内治疗而获得时，对类固醇生成没有影响。 因此，我们得出结论，过氧化氢通过阻断胆固醇向线粒体的细胞内转运或胆固醇跨线粒体外膜的易位来抑制类固醇合成。
In luteal and granulosa cells, hydrogen peroxide abruptly inhibits activation of adenylate cyclase by receptor-bound gonadotropin and blocks steroidogenesis. In the present studies a post-cAMP site of peroxide action on inhibition of steroidogenesis was investigated. Steroidogenesis, stimulated by dibutyrl or 8-bromo-cAMP, was inhibited by hydrogen peroxide. Yet, cAMP-dependent protein kinase activation in cytosol or intact cells was unaffected by peroxide treatment. Hydrogen peroxide also did not inhibit the activity of cholesterol esterase and acyl coenzyme-A:acyltransferase. Progesterone synthesis was maximally increased 5- to 50-fold with 25- and 22-hydroxycholesterol, respectively. Unlike that seen with cAMP analogs and LH, however, progestin synthesis stimulated by these cell-and mitochondria-permeant cholesterol analogs was not inhibited by hydrogen peroxide. Treatment of animals with amino-glutethimide produces a marked accumulation of steroidogenic cholesterol substrate and a large increase in hormone-independent steroidogenesis in subsequently isolated and washed luteal tissue. In this paradigm, hydrogen peroxide did not inhibit elevated basal progesterone synthesis in luteal cells produced by in vivo aminoglutethimide treatment, yet LH-stimulated steroidogenesis was blocked. However, treatment of luteal cells with hydrogen peroxide inhibited pregnenolone synthesis in isolated mitochondria, an effect partially reversed by the addition of luteal cell cytosol. In summary, while peroxide inhibited cAMP-dependent steroidogenesis, it did not appear to inhibit protein kinase activation or mobilization of cholesterol from intracellular esterified stores. Although peroxide inhibited pregnenolone synthesis, it had no effect on steroidogenesis when substrate was made available by either addition of cholesterol analogs or prior treatment with aminoglutethimide in vivo. We conclude, therefore, that hydrogen peroxide inhibits steroidogenesis by blocking intracellular transport of cholesterol to mitochondria or translocation of cholesterol across the outer mitochondrial membrane.