Dynamin is involved in endolysosomal cholesterol delivery to the endoplasmic reticulum: Role in cholesterol homeostasis
Dynamin is involved in endolysosomal cholesterol delivery to the endoplasmic reticulum: Role in cholesterol homeostasis
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DOI：
10.1111/j.1600-0854.2006.00435.x
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发表时间：
2006-07-01
期刊：
影响因子：
4.5
通讯作者：
Lamaze, Christophe
中科院分区：
文献类型：
--
作者：
Robinet, Peggy;Fradagrada, Alexandre;Lamaze, Christophe
胆固醇是哺乳动物细胞中最重要的膜组分之一，在多种细胞功能中起着关键作用。现在已经确定，细胞内胆固醇转运有助于调节细胞胆固醇稳态的机制，但还不清楚。在这项研究中，我们研究了网格蛋白和动力蛋白依赖性运输的调节机制参与胆固醇稳态的作用。因此，监测三种主要的甾醇敏感基因，即甾醇调节元件结合蛋白2（SREBP-2）、羟甲基戊二酰辅酶A（HMGCoA）还原酶和低密度脂蛋白（LDL）受体的表达水平，以研究细胞对添加LDL衍生的胆固醇的反应。我们发现，抑制网格蛋白依赖的内吞作用对胆固醇的细胞内分布和固醇敏感基因的调节没有影响。相反，抑制发动蛋白活性导致SREBP-2、HMGCoA还原酶和LDL受体基因缺乏调节。免疫定位研究沿着游离胆固醇和酯化胆固醇的测量结果表明，发动蛋白失活导致游离胆固醇（FC）在晚期内体（LE）/溶酶体隔室中蓄积，导致调节性胆固醇向内质网（ER）的递送不足，内质网（ER）是固醇敏感基因转录控制的发生地。因此，我们的数据表明，发动蛋白在胆固醇从LE/溶酶体网络到ER的传递中起着关键作用，并突出了LE运输在胆固醇稳态中的重要性。
Cholesterol is one of the most essential membrane components in mammalian cells and plays a critical role in several cellular functions. It is now established that intracellular cholesterol transport contributes to the regulation of cellular cholesterol homeostasis by mechanisms that are yet poorly defined. In this study, we examined the role of clathrin- and dynamin-dependent trafficking on the regulatory machinery involved in cholesterol homeostasis. Thus, expression levels of three major sterol-sensitive genes, that is sterol-regulatory element binding protein 2 (SREBP-2), hydroxymethylglutaryl-coenzyme A (HMGCoA) reductase and low-density lipoprotein (LDL) receptor, were monitored to study the cell response to the addition of LDL-derived cholesterol. We found that inhibition of clathrin-dependent endocytosis had no effect on the intracellular distribution of cholesterol and the regulation of sterol-sensitive genes. In contrast, inhibition of dynamin activity resulted in the lack of regulation of SREBP-2, HMGCoA reductase and LDL receptor genes. Immunolocalization studies along with the measure of free and esterified cholesterol indicated that dynamin inactivation led to the accumulation of free cholesterol (FC) within the late endosomal (LE)/lysosomal compartment resulting in insufficient delivery of regulatory cholesterol to the endoplasmic reticulum (ER) where the transcriptional control of sterol-sensitive genes occurs. Our data therefore indicate that dynamin plays a critical role in the delivery of cholesterol from the LE/lysosomal network to the ER and highlight the importance of LE trafficking in cholesterol homeostasis.