Shu Liming, Shayman James A
Nephrology Division, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109, USA.
J Biol Chem. 2007 Jul 20;282(29):20960-7. doi: 10.1074/jbc.M702436200. Epub 2007 May 29.
Cardiovascular complications, including stroke and myocardial infarction, result in premature mortality in patients with Fabry disease, an X-linked deficiency of alpha-galactosidase A (alpha-Gal A). The enzymatic defect results in the deposition of globotriaosylceramide (Gb3) in the vascular endothelium. To better understand the underlying pathogenesis of Fabry disease, the caveolar lipid content of primary cultured mouse aortic endothelial cells isolated from alpha-Gal A null mice was measured. Lipid mass analysis revealed that the excessive Gb3 in cultured alpha-Gal A-deficient mouse aortic endothelial cells accumulated in endothelial plasma membrane caveolar fractions. The levels of glucosylceramide and lactosylceramide increased in parallel with Gb3 levels in an age-dependent manner, whereas globotetraosylceramide (Gb4) levels reached maximal levels by 6 months of age and then rapidly decreased at older ages. The levels of cholesterol enriched in caveolar membranes declined in parallel with the progressive deposition of Gb3. Depleting Gb3 with recombinant human alpha-Gal A protein or d-threo-ethylenedioxyphenyl-P4, an inhibitor of glucosylceramide synthase, restored cholesterol in cultured alpha-Gal A-deficient mouse aortic endothelial cell caveolae. By contrast, recombinant human alpha-Gal A was less effective in normalizing the cholesterol content. These results demonstrate the caveolar accumulation of glycosphingolipids in an in vitro model of a lysosomal storage disease and raise the possibility that dynamic changes in the composition of plasma membrane lipid microdomains may mediate the endothelial dysfunction seen in Fabry disease.
心血管并发症，包括中风和心肌梗死，导致法布里病患者过早死亡，法布里病是一种X连锁的α-半乳糖苷酶A（α-Gal A）缺乏症。酶缺陷导致球三糖神经酰胺（Gb3）在血管内皮中沉积。为了更好地理解法布里病的潜在发病机制，测量了从α-Gal A基因敲除小鼠分离的原代培养小鼠主动脉内皮细胞的小窝脂质含量。脂质质量分析显示，培养的α-Gal A缺陷小鼠主动脉内皮细胞中过量的Gb3在内皮细胞质膜小窝组分中积累。葡萄糖神经酰胺和乳糖神经酰胺的水平与Gb3水平呈年龄依赖性平行增加，而球四糖神经酰胺（Gb4）水平在6个月龄时达到最高水平，然后在老年时迅速下降。富含小窝膜的胆固醇水平与Gb3的逐渐沉积平行下降。用重组人α-Gal A蛋白或葡萄糖神经酰胺合酶抑制剂d-苏式-乙二氧基苯基-P4消耗Gb3可恢复培养的α-Gal A缺陷小鼠主动脉内皮细胞小窝中的胆固醇。相比之下，重组人α-Gal A在使胆固醇含量正常化方面效果较差。这些结果证明了在溶酶体贮积病的体外模型中糖鞘脂在小窝中的积累，并提出了质膜脂质微区组成的动态变化可能介导法布里病中所见内皮功能障碍的可能性。
