Selective inhibition of cholesterol biosynthesis in brain cells by squalestatin 1.
Selective inhibition of cholesterol biosynthesis in brain cells by squalestatin 1.
复制标题
squalestatin 1选择性抑制脑细胞胆固醇生物合成。
DOI：
10.1046/j.1471-4159.1995.65031365.x
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发表时间：
1995
影响因子：
4.7
通讯作者：
Waechter,CJ
中科院分区：
文献类型：
--
作者：
Crick,DC;Suders,J;Kluthe,CM;Andres,DA;Waechter,CJ
通过体外酶学和体内代谢标记实验评价角鲨烯抑制素1（SQ）对角鲨烯合酶和其他利用焦磷酸法呢酯（F-P-P）作为底物的酶的影响，以确定药物是否选择性抑制脑细胞中的胆固醇生物合成。胚胎大鼠脑原代培养物膜组分的直接体外酶研究（IC 50 = 37 nM），猪脑（IC 50 = 21 nM）和C6胶质瘤细胞（IC 50 = 35 nM）表明SQ有效抑制角鲨烯合酶活性，但对催化F-P-P转化为焦磷酸聚异戊二烯基的长链异戊二烯基转移酶没有影响（Poly-P-P），磷酸二氢甘油酯（Dol-P）的前体。SQ对F-P-P合酶、牛脑中部分纯化的GG-P-P合酶催化的[3 H] F-P-P转化为香叶基香叶基焦磷酸（GG-P-P）、大鼠脑法尼基转移酶催化的重组H-p21 ras的酶法尼基化或大鼠脑香叶基香叶基转移酶催化的重组Rab 1A的酶法香叶基香叶基化也没有影响。与SQ选择性阻断角鲨烯合成一致，当C6胶质细胞用[3 H]甲羟戊酸内酯代谢标记时，药物抑制标记前体掺入角鲨烯和胆固醇（IC 50 = 3-5 µM），但对Dol-P，泛醌（CoQ）和异戊二烯化蛋白的标记没有影响或略有刺激。这些结果表明SQ通过选择性抑制角鲨烯合酶阻断脑细胞中胆固醇的生物合成。因此，SQ提供了一个有用的工具，用于评估神经生物学过程中从头胆固醇生物合成的强制性要求，而不干扰其他涉及F-P-P的关键反应。
The effect of squalestatin 1 (SQ) on squalene synthase and other enzymes utilizing farnesyl pyrophosphate (F‐P‐P) as substrate was evaluated by in vitro enzymological and in vivo metabolic labeling experiments to determine if the drug selectively inhibited cholesterol biosynthesis in brain cells. Direct in vitro enzyme studies with membrane fractions from primary cultures of embryonic rat brain (IC50= 37 nM), pig brain (IC50= 21 nM), and C6 glioma cells (IC50= 35 nM) demonstrated that SQ potently inhibited squalene synthase activity but had no effect on the long‐chaincis‐isoprenyltransferase catalyzing the conversion of F‐P‐P to polyprenyl pyrophosphate (Poly‐P‐P), the precursor of dolichyl phosphate (Dol‐P). SQ also had no effect on F‐P‐P synthase; the conversion of [3H]F‐P‐P to geranylgeranyl pyrophosphate (GG‐P‐P) catalyzed by partially purified GG‐P‐P synthase from bovine brain; the enzymatic farnesylation of recombinant H‐p21rasby rat brain farnesyltransferase; or the enzymatic geranylgeranylation of recombinant Rab1A, catalyzed by rat brain geranylgeranyltransferase. Consistent with SQ selectively blocking the synthesis of squalene, when C6 glial cells were metabolically labeled with [3H]mevalonolactone, the drug inhibited the incorporation of the labeled precursor into squalene and cholesterol (IC50= 3–5 µM) but either had no effect or slightly stimulated the labeling of Dol‐P, ubiquinone (CoQ), and isoprenylated proteins. These results indicate that SQ blocks cholesterol biosynthesis in brain cells by selectively inhibiting squalene synthase. Thus, SQ provides a useful tool for evaluating the obligatory requirement for de novo cholesterol biosynthesis in neurobiological processes without interfering with other critical reactions involving F‐P‐P.