Tool Compounds Robustly Increase Turnover of an Artificial Substrate by Glucocerebrosidase in Human Brain Lysates

Mutations in glucocerebrosidase (GBA1) cause Gaucher disease and also represent a common risk factor for Parkinson’s disease and Dementia with Lewy bodies. Recently, new tool molecules were described which can increase turnover of an artificial substrate 4MUG when incubated with mutant N370S GBA1 from human spleen. Here we show that these compounds exert a similar effect on the wild-type enzyme in a cell-free system. In addition, these tool compounds robustly increase turnover of 4MUG by GBA1 derived from human cortex, despite substantially lower glycosylation of GBA1 in human brain, suggesting that the degree of glycosylation is not important for compound binding. Surprisingly, these tool compounds failed to robustly alter GBA1 turnover of 4MUG in the mouse brain homogenate. Our data raise the possibility that in vivo models with humanized glucocerebrosidase may be needed for efficacy assessments of such small molecules.

葡萄糖脑苷脂酶（glucocerebrosidase, GBA1）的突变可引发戈谢病（Gaucher disease），同时也是帕金森病（Parkinson’s disease）与路易体痴呆（Dementia with Lewy bodies）的常见风险因子。近期已有研究报道一类新型工具分子，该类分子与人类脾脏来源的突变型N370S葡萄糖脑苷脂酶共孵育时，可提升人工底物4MUG的酶促周转效率。本研究证实，此类化合物在无细胞体系中对野生型葡萄糖脑苷脂酶亦可发挥类似作用。此外，尽管人类大脑组织中葡萄糖脑苷脂酶的糖基化程度显著更低，但此类工具分子仍可有效提升人类大脑皮层来源的葡萄糖脑苷脂酶对4MUG的催化周转效率，这提示糖基化程度对化合物结合并无显著影响。令人意外的是，此类工具化合物无法有效改变小鼠脑组织匀浆中葡萄糖脑苷脂酶对4MUG的催化周转效率。本研究数据表明，此类小分子化合物的药效评估或许需要采用搭载人源化葡萄糖脑苷脂酶的体内模型。