25-hydroxycholesterol acts in the Golgi compartment to induce degradation of tyrosinase
25-hydroxycholesterol acts in the Golgi compartment to induce degradation of tyrosinase
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DOI：
10.1111/j.1600-0749.2004.00161.x
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发表时间：
2004-08-01
期刊：
影响因子：
--
通讯作者：
Orlow, SJ
中科院分区：
文献类型：
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作者：
Hall, AM;Krishnamoorthy, L;Orlow, SJ
氧固醇在胆固醇稳态中起重要作用。25-特别是羟基胆固醇（25 HC）已被证明可通过氧化固醇结合蛋白和氧化固醇相关蛋白、固醇调节元件结合蛋白和胆固醇生物合成的限速酶羟甲基戊二酰辅酶A还原酶来调节胆固醇稳态。我们检查了25 HC对培养的小鼠黑素细胞色素沉着的影响，并证明色素沉着减少，IC 50为0.34 μ M，黑素蛋白酪氨酸酶水平显着降低。脉冲追踪研究表明，25 HC处理的细胞增强降解酪氨酸酶，黑色素合成的限速酶，内质网（ER）和高尔基体成熟。在25 HC处理的黑素细胞中，ER/顺式高尔基体陷阱蛋白复合物的成员GS 28的蛋白水平也减少，但是ER伴侣钙连接蛋白和顺式高尔基体基质蛋白GM 130的水平不受影响。25 HC对酪氨酸酶的作用可被4 α-烯丙基胆甾烷-3 α-醇完全逆转，4 α-烯丙基胆甾烷-3 α-醇是一种通过逆转25 HC对胆固醇稳态作用的能力而鉴定的甾醇。最后，添加25 HC的脂质缺乏血清抑制正确的酪氨酸酶的加工。我们的结论是，25 HC的行为在高尔基室调节色素沉着的机制与胆固醇稳态共享。
Oxysterols play a significant role in cholesterol homeostasis. 25-Hydroxycholesterol (25HC) in particular has been demonstrated to regulate cholesterol homeostasis via oxysterol-binding protein and oxysterol-related proteins, the sterol regulatory element binding protein, and the rate-limiting enzyme of cholesterol biosynthesis, hydroxymethylglutaryl coenzyme A reductase. We have examined the effect of 25HC on pigmentation of cultured murine melanocytes and demonstrated a decrease in pigmentation with an IC50 of 0.34 muM and a significant diminution in levels of melanogenic protein tyrosinase. Pulse-chase studies of 25HC-treated cells demonstrated enhanced degradation of tyrosinase, the rate-limiting enzyme of melanin synthesis, following endoplasmic reticulum (ER) and Golgi maturation. Protein levels of GS28, a member of an ER/cis-Golgi SNARE protein complex, were also diminished in 25HC-treated melanocytes, however levels of the ER chaperone calnexin and the cis-Golgi matrix protein GM130 were unaffected. Effects of 25HC on tyrosinase were completely reversed by 4alpha-allylcholestan-3alpha-ol, a sterol identified by its ability to reverse effects of 25HC on cholesterol homeostasis. Finally, the addition of 25HC to lipid deficient serum inhibited correct processing of tyrosinase. We conclude that 25HC acts in the Golgi compartment to regulate pigmentation by a mechanism shared with cholesterol homeostasis.