Krabbe disease is a sphingolipidosis characterized by the genetic deficiency of the acid hydrolase β-galactosylceramidase (GALC). Most of the studies concerning the biological role of GALC performed on Krabbe patients and -deficient mice (an authentic animal model of the disease) indicate that the pathogenesis of this disorder is the consequence of the accumulation of the neurotoxic GALC substrate β-galactosylsphingosine (psychosine), ignoring the possibility that this enzyme may exert a wider biological impact. Indeed, limited information is available about the effect of GALC downregulation on the cell lipidome in adult and developing organisms. The teleost zebrafish () has emerged as a useful platform to model human genetic diseases, including sphingolipidoses, and two co-orthologs have been identified in zebrafish ( and ). Here, we investigated the effect of the competitive and irreversible GALC inhibitor β-galactose-cyclophellitol (GCP) on the lipid profile of zebrafish embryos. Molecular modelling indicates that GCP can be sequestered in the catalytic site of the enzyme and covalently binds human GALC, and the zebrafish Galca and Galcb proteins in a similar manner. Accordingly, GCP inhibits the β-galactosylceramide hydrolase activity of zebrafish and , leading to significant alterations of the lipidome of zebrafish embryos. These results indicate that the lack of GALC activity deeply affects the lipidome during the early stages of embryonic development, and thereby provide insights into the pathogenesis of Krabbe disease.

中文翻译：

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不可逆β-半乳糖神经酰胺酶抑制剂对斑马鱼胚胎脂质谱的影响

克拉伯病是一种鞘脂沉积症，其特征是酸性水解酶 β-半乳糖神经酰胺酶 (GALC) 遗传缺陷。大多数关于 GALC 在 Krabbe 患者和缺陷小鼠（该疾病的真实动物模型）上进行的生物学作用的研究表明，这种疾病的发病机制是神经毒性 GALC 底物 β-半乳糖基鞘氨醇（精神鞘氨醇）积累的结果。 ），忽略了这种酶可能发挥更广泛的生物学影响的可能性。事实上，关于 GALC 下调对成体和发育中生物体细胞脂质组的影响的信息有限。硬骨鱼斑马鱼 () 已成为模拟人类遗传疾病（包括鞘脂沉积症）的有用平台，并且在斑马鱼 ( 和 ) 中已鉴定出两种共同直向同源物。在这里，我们研究了竞争性且不可逆的 GALC 抑制剂 β-半乳糖环苯乙醇 (GCP) 对斑马鱼胚胎脂质谱的影响。分子模型表明，GCP 可以被隔离在酶的催化位点，并以类似的方式共价结合人类 GALC、斑马鱼 Galca 和 Galcb 蛋白。因此，GCP 抑制斑马鱼的 β-半乳糖神经酰胺水解酶活性，导致斑马鱼胚胎脂质组的显着改变。这些结果表明，GALC 活性的缺乏深刻影响胚胎发育早期阶段的脂质组，从而为克拉伯病的发病机制提供了见解。