Carbohydrate-remodelled acid α-glucosidase with higher affinity for the cation-independent mannose 6-phosphate receptor demonstrates improved delivery to muscles of Pompe mice

作者：Yunxiang Zhu, Xuemei Li, Alison McVie‐Wylie, Canwen Jiang, Beth L. Thurberg, Nina Raben, Robert J. Mattaliano, Seng H. Cheng · 发表于：Biochemical Journal · 年份：2005 · DOI：10.1042/bj20050364 · 被引用次数：111 · 研究领域：Lysosomal Storage Disorders Research、Glycogen Storage Diseases and Myoclonus、Carbohydrate Chemistry and Synthesis

To enhance the delivery of rhGAA (recombinant GAA, where GAA stands for acid alpha-glucosidase) to the affected muscles in Pompe disease, the carbohydrate moieties on the enzyme were remodelled to exhibit a high affinity ligand for the CI-MPR (cation-independent M6P receptor, where M6P stands for mannose 6-phosphate). This was achieved by chemically conjugating on to rhGAA, a synthetic oligosaccharide ligand bearing M6P residues in the optimal configuration for binding the receptor. The carbonyl chemistry used resulted in the conjugation of approx. six synthetic ligands on to each enzyme. The resulting modified enzyme [neo-rhGAA (modified recombinant human GAA harbouring synthetic oligosaccharide ligands)] displayed near-normal specific activity and significantly increased affinity for the CI-MPR. However, binding to the mannose receptor was unaffected despite the introduction of additional mannose residues in neo-rhGAA. Uptake studies using L6 myoblasts showed neo-rhGAA was internalized approx. 20-fold more efficiently than the unmodified enzyme. Administration of neo-rhGAA into Pompe mice also resulted in greater clearance of glycogen from all the affected muscles when compared with the unmodified rhGAA. Comparable reductions in tissue glycogen levels in the Pompe mice were realized using an approx. 8-fold lower dose of neo-rhGAA in the heart and diaphragm and an approx. 4-fold lower dose in the skeletal muscles. Treatment of older Pompe mice, which are more refractory to e...