Peripheral-type benzodiazepine receptor-mediated action of steroidogenic acute regulatory protein on cholesterol entry into Leydig cell mitochondria
Peripheral-type benzodiazepine receptor-mediated action of steroidogenic acute regulatory protein on cholesterol entry into Leydig cell mitochondria
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DOI：
10.1210/me.2004-0307
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发表时间：
2005-02-01
影响因子：
--
通讯作者：
Papadopoulos, V
中科院分区：
文献类型：
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作者：
Hauet, T;Yao, ZX;Papadopoulos, V
激素诱导的类固醇生物合成始于胆固醇从细胞内储存转移至线粒体。类固醇生成急性调节蛋白（StAR）和外周型苯二氮卓受体（PBR）与类固醇生成的这一速率决定步骤有关。用或不用PBR和StAR反义寡脱氧核苷酸(ODN)处理MA-10小鼠Leydig肿瘤细胞，然后用饱和浓度的人绒毛膜促性腺激素处理。用ODN反义而非错义处理这两种蛋白质会抑制各自的蛋白质表达以及细胞响应人绒毛膜促性腺激素合成类固醇的能力。用PBR反义ODN或PBR转导肽拮抗剂处理细胞，导致成熟线粒体30-kDa StAR蛋白的积累受到抑制，这表明PBR的存在是StAR导入线粒体所必需的。将体外转录/翻译的 37-kDa StAR 或 Tom20（外膜转位酶）和 StAR (Tom/StAR) 的融合蛋白添加到从对照细胞分离的线粒体中，增加了孕烯醇酮的形成。从用 PBR 反义（而非错义）ODN 处理的细胞中分离出的线粒体未能形成孕烯醇酮，也无法对 StAR 或 Tom/StAR 蛋白作出反应。将体外转录/翻译的PBR（而非缺失胆固醇结合结构域的PBR）重新掺入MA-10线粒体中，挽救了线粒体形成类固醇的能力以及线粒体响应StAR和Tom/StAR蛋白的能力。这些数据表明，StAR 和 PBR 蛋白都是类固醇生成机制中不可或缺的元素，并以协调的方式发挥作用，将胆固醇转移到线粒体中。
Hormone- induced steroid biosynthesis begins with the transfer of cholesterol from intracellular stores into mitochondria. Steroidogenic acute regulatory protein ( StAR) and peripheral- type benzodiazepine receptor ( PBR) have been implicated in this rate- determining step of steroidogenesis. MA- 10 mouse Leydig tumor cells were treated with and without oligodeoxynucleotides ( ODNs) antisense to PBR and StAR followed by treatment with saturating concentrations of human choriogonadotropin. Treatment with ODNs antisense but not missense for both proteins inhibited the respective protein expression and the ability of the cells to synthesize steroids in response to human choriogonadotropin. Treatment of the cells with either ODNs antisense to PBR or a transducible peptide antagonist to PBR resulted in inhibition of the accumulation of the mature mitochondrial 30- kDa StAR protein, suggesting that the presence of PBR is required for StAR import into mitochondria. Addition of in vitro transcribed/ translated 37- kDa StAR or a fusion protein of Tom20 ( translocase of outer membrane) and StAR ( Tom/ StAR) to mitochondria isolated from control cells increased pregnenolone formation. Mitochondria isolated from cells treated with ODNs antisense, but not missense, to PBR failed to form pregnenolone and respond to either StAR or Tom/ StAR proteins. Reincorporation of in vitro transcribed/ translated PBR, but not PBR missing the cholesterol- binding domain, into MA- 10 mitochondria rescued the ability of the mitochondria to form steroids and the ability of the mitochondria to respond to StAR and Tom/ StAR proteins. These data suggest that both StAR and PBR proteins are indispensable elements of the steroidogenic machinery and function in a coordinated manner to transfer cholesterol into mitochondria.