Hein Leanne K, Meikle Peter J, Hopwood John J, Fuller Maria
Department of Genetic Medicine, Children, Youth and Women's Health Service, 72 King William Road, North Adelaide, SA 5006, Australia.
Mol Genet Metab. 2007 Dec;92(4):336-45. doi: 10.1016/j.ymgme.2007.08.001. Epub 2007 Sep 18.
Glucosylceramide (GC) is a metabolic intermediate derived from the cellular turnover of membrane gangliosides and globosides. The catabolism of GC is impaired in Gaucher disease (GD) and consequently GC accumulates in affected cells leading to clinical manifestations of GD. The primary cell type affected in GD is the macrophage, and we investigated what effect excess GC has on the spatial coordination of other sphingolipids and phospholipids in a macrophage model of GD. A THP-1 macrophage model of GD was established by supplementation of the culture media with conduritol B epoxide, a specific irreversible inhibitor of acid beta-glucosidase. This cell model accumulated up to 12-fold more GC compared with untreated cells. Sub-cellular fractionation showed that, initially, the primary site of GC accumulation was the lysosome but as more GC accumulated it distributed relatively evenly across the cell and was present in all sub-cellular fractions. We also observed secondary elevations in the concentrations of ceramide, di- and trihexosylceramide and phosphatidylglycerol, which all had similar sub-cellular distributions to that of GC, initially increasing in the lysosome and then throughout the sub-cellular compartments. Our results suggest that with excess GC accumulation, the pathway trafficking GC to the lysosome becomes saturated and GC as well as other sphingolipids are shunted to other parts of the cell. The presence of these sphingolipids at non-physiological concentrations is likely to interfere with other biochemical pathways outside the lysosome, leading to cell dysfunction and ultimately pathological mechanisms apparent in GD, such as macrophage activation.
葡糖神经酰胺(GC)是一种由膜神经节苷脂和球苷脂的细胞更新产生的代谢中间体。在戈谢病(GD)中,GC的分解代谢受损,因此GC在受影响的细胞中积累,导致GD的临床表现。GD中受影响的主要细胞类型是巨噬细胞,我们研究了过量GC对GD巨噬细胞模型中其他鞘脂和磷脂空间协调的影响。通过在培养基中添加酸性β-葡萄糖苷酶的特异性不可逆抑制剂环氧康杜醇B,建立了GD的THP-1巨噬细胞模型。与未处理的细胞相比,该细胞模型积累的GC多至12倍。亚细胞分级分离表明,最初,GC积累的主要部位是溶酶体,但随着更多GC的积累,它相对均匀地分布在整个细胞中,并存在于所有亚细胞组分中。我们还观察到神经酰胺、二己糖神经酰胺和三己糖神经酰胺以及磷脂酰甘油浓度的二次升高,它们的亚细胞分布与GC相似,最初在溶酶体中增加,然后在整个亚细胞区室中增加。我们的结果表明,随着GC的过量积累,将GC转运至溶酶体的途径变得饱和,GC以及其他鞘脂被分流至细胞的其他部位。这些鞘脂以非生理浓度存在可能会干扰溶酶体外的其他生化途径,导致细胞功能障碍,并最终导致GD中明显的病理机制,如巨噬细胞活化。