Mouse Model for Zellweger Syndrome

描述(摘自申请者的摘要)：最近的研究表明 胆固醇对正常的大脑发育是必不可少的，而中枢 神经系统主要依赖于胆固醇的从头合成。我们有 研究表明，过氧酶体对于胆固醇的生物合成是必不可少的，因为 事实上，法尼基二磷酸(FPP)的整个生物合成途径 甲氧戊酸甲酯仅存在于过氧化体中。因此，过氧酶体 必须在中枢神经系统的这一过程中发挥关键的作用。然而，没有 关于过氧化物型异戊二烯/胆固醇生物合成的信息可用 正常脑内途径或异戊二烯代谢的区间化 在中枢神经系统。Zellweger综合征的动物模型(即，过氧化物型PEX2 敲除小鼠)是最近发展起来的。这些老鼠提供了一个重要的 研究中枢神经系统过氧化体功能在发病机制中作用的模型 在这些疾病中观察到的神经异常。在本建议书中 我们提出了这样一种假设，即过氧化物酶体在 类异戊二烯/胆固醇在中枢神经系统和PEX2基因敲除小鼠中的生物合成 中枢神经系统中类异戊二烯/胆固醇的生物合成发生了显著的变化。 为了验证这一假设，提出了以下具体目标： 1)确定过氧化体在类异戊二烯/胆固醇生物合成中的作用 在正常新生小鼠的大脑中。新生儿类异戊二烯的生物合成途径 小鼠的大脑将通过亚细胞分离、活性和 免疫印迹分析梯度组分，免疫组织化学和 原位杂交技术。我们还将确定是否有亲属 过氧化体和内质网对甾醇/非甾醇的贡献 生物合成在发育过程中发生变化。 2)检测脂质成分和胆固醇/二羟苯二醇代谢的缺陷 在PEX2缺陷小鼠中。我们将确定胆固醇的调节如何 酶和途径中的限速步骤可能会被 胆固醇合成的分解是由于缺乏 过氧酶体。 这些研究旨在确定是否有牵连的基础 在齐薇格小鼠身上观察到的一些神经缺陷中的胆固醇。 PEX2缺陷者类异戊二烯/胆固醇代谢的比较 而正常的动物可以洞察到这种机制(S) 在基因敲除小鼠中发现的神经学表型。

DESCRIPTION(adapted from applicant's abstract): Recent studies have indicated that cholesterol is essential for normal brain development and that the central nervous system depends mainly on de novo cholesterol biosynthesis. We have shown that peroxisomes are essential for cholesterol biosynthesis, due to the fact that the entire pathway for the biosynthesis of farnesyl diphosphate (FPP) from mevalonate is exclusively found in peroxisomes. Therefore, peroxisomes must play a critical functional role in this process in the CNS. However, no information is available on the peroxisomal isoprenoid/cholesterol biosynthesis pathway in normal brain or on the compartmentalization of isoprene metabolism in the CNS. An animal model for Zellweger syndrome (i.e., a peroxisomal PEX2 knockout mouse) has been recently developed. These mice provide an important model to study the role of peroxisomal function in the CNS in the pathogenesis of the neurological abnormalities observed in these diseases. In this proposal we address the hypothesis that peroxisomes have a central role in isoprenoid/cholesterol biosynthesis in the CNS and that in PEX2 knockout mice, the isoprenoid/cholesterol biosynthesis in the CNS is significantly altered. To test this hypothesis the following specific aims are proposed: 1) To determine the role of peroxisomes in isoprenoid/cholesterol biosynthesis in normal neonatal mouse brain. The isoprenoid biosynthetic pathway in neonatal mouse brain will be analyzed by subcellular fractionation, activity and immunoblot analysis of the gradient fractions, and immunohistochemistry and in situ hybridization techniques. We will also determine if the relative distribution of peroxisomal and ER contribution to sterol/non-sterol biosynthesis changes during development. 2) To test for defects in lipid composition and cholesterol/dolichol metabolism in PEX2 deficient mice. We will determine how the regulation of cholesterol enzymes and the rate limiting steps in the pathway may be altered by the decompartmentalization of cholesterol synthesis due to the absence of peroxisomes. The studies are designed to ascertain whether there is a basis to implicate cholesterol in some of the neurologic defects observed in the Zellweger mouse. Thus a comparison of isoprenoid/cholesterol metabolism in the PEX2 deficient and normal animals can render insight into the mechanism(s) for the neurological phenotype seen in the knockout mice.