Garver W S, Erickson R P, Wilson J M, Colton T L, Hossain G S, Kozloski M A, Heidenreich R A
Angel Charity for Children Wings for Genetic Research, Section of Medical and Molecular Genetics, The University of Arizona, College of Medicine, Tucson 85724, USA.
Biochim Biophys Acta. 1997 Oct 24;1361(3):272-80. doi: 10.1016/s0925-4439(97)00047-1.
Niemann-Pick type C (NPC) is an autosomal recessive disease characterized by impaired cholesterol homeostasis due to a defect in the intracellular transport of unesterified cholesterol. While accumulation of lysosomal cholesterol is the most apparent microscopic finding, cholesterol has also been shown to accumulate in the trans-cisternae of the Golgi apparatus. Caveolin-1, a cholesterol-binding protein that cycles between the Golgi apparatus and the plasma membrane, has been hypothesized to participate in cholesterol transport. Using the BALB/c murine model for NPC disease, we found that the expression of caveolin-1 in total liver homogenates from heterozygous and homozygous affected animals was altered. Immunoblot analysis of liver homogenates from heterozygous mice revealed that caveolin-1 is significantly (p < 0.005) elevated, 4.9 fold, compared to normal mice. Total liver homogenates from homozygous affected mice also had a significant (p < 0.05) increase in caveolin-1 expression, 1.6 fold, compared to normal mice. Immunohistochemical staining of liver cross-sections revealed that the increased caveolin-1 was localized to sinusoidal endothelial cells in heterozygous mice. The Triton insoluble floating fraction (TIFF) was isolated using liver from each genotype and analyzed for caveolin-1 expression. Caveolin-1 in the TIFF from heterozygous mice was significantly (p < 0.01) elevated, 1.8 fold, compared to normal and homozygous affected animals; normal and homozygous affected animals, however, were not significantly different from each other. The TIFF isolated from homozygous affected mice revealed a 15 fold increase in unesterified cholesterol compared to the TIFF isolated from heterozygous and normal mice. In summary, these findings demonstrate an altered expression of caveolin-1 in liver from heterozygous and homozygous NPC mice and increased concentration of cholesterol from TIFF in homozygous affected NPC mice. The identification of these alterations in the TIFF suggests involvement of detergent insoluble membrane structures, possibly caveolae and/or detergent insoluble glycosphingolipid-enriched complexes (DIGs), in the cholesterol trafficking defect in this disorder.
尼曼-匹克C型（NPC）病是一种常染色体隐性疾病，其特征是由于未酯化胆固醇的细胞内运输缺陷导致胆固醇稳态受损。虽然溶酶体胆固醇的积累是最明显的微观发现，但胆固醇也已被证明会在高尔基体的反式扁平囊泡中积累。小窝蛋白-1是一种在高尔基体和质膜之间循环的胆固醇结合蛋白，据推测它参与胆固醇运输。使用BALB/c小鼠NPC病模型，我们发现杂合子和纯合子患病动物肝脏总匀浆中小窝蛋白-1的表达发生了改变。对杂合子小鼠肝脏匀浆的免疫印迹分析显示，与正常小鼠相比，小窝蛋白-1显著升高（p < 0.005），为4.9倍。纯合子患病小鼠的肝脏总匀浆中小窝蛋白-1的表达也显著增加（p < 0.05），与正常小鼠相比为1.6倍。肝脏横截面的免疫组织化学染色显示，杂合子小鼠中小窝蛋白-1的增加定位于窦状内皮细胞。使用每种基因型的肝脏分离出Triton不溶性漂浮组分（TIFF），并分析小窝蛋白-1的表达。与正常和纯合子患病动物相比，杂合子小鼠TIFF中的小窝蛋白-1显著升高（p < 0.01），为1.8倍；然而，正常和纯合子患病动物之间没有显著差异。与从杂合子和正常小鼠分离的TIFF相比，从纯合子患病小鼠分离的TIFF显示未酯化胆固醇增加了15倍。总之，这些发现表明杂合子和纯合子NPC小鼠肝脏中小窝蛋白-1的表达发生改变，并且纯合子患病NPC小鼠TIFF中的胆固醇浓度增加。TIFF中这些改变的鉴定表明去污剂不溶性膜结构，可能是小窝和/或去污剂不溶性富含糖鞘脂的复合物（DIGs），参与了该疾病中胆固醇转运缺陷。
