Grace M E, Berg A, He G S, Goldberg L, Horowitz M, Grabowski G A
Department of Pediatrics, Mount Sinai School of Medicine, New York, NY 10029-6574.
Am J Hum Genet. 1991 Sep;49(3):646-55.
To investigate the molecular basis for the distinct neuronopathic phenotypes of Gaucher disease, acid beta-glucosidases expressed from mutant DNAs in Gaucher disease type 2 (acute) and type 3 (subacute) patients were characterized in fibroblasts and with the baculovirus expression system in insect cells. Expression of the mutant DNA encoding a proline-for-leucine substitution at amino acid 444 (L444P) resulted in a catalytically defective, unstable acid beta-glucosidase in either fibroblasts from L444P/L444P homozygotes or in insect cells. This mutation was found to be homoallelic in subacute neuronopathic (type 3) Gaucher disease. In comparison, expression of the mutant cDNA encoding an arginine-for-proline substitution at amino acid 415 (P415R) resulted in an inactive and unstable protein in insect cells. This allele was found only in a type 2 patient with the L444P/P415R genotype. The substantial variation in the type 3 phenotype (L444P homozygotes) suggests the complex nature of the molecular basis of phenotypic variation in Gaucher disease. Yet, the association of neuronopathic phenotypes with alleles producing severely compromised (L444P) or functionally null (P415R) enzymes indicates that the effective level of residual activity at the lysosome is likely to be a major determinant of the severity of Gaucher disease.
为了研究戈谢病不同神经病变表型的分子基础，我们对2型（急性）和3型（亚急性）戈谢病患者突变DNA所表达的酸性β-葡萄糖苷酶在成纤维细胞中以及利用杆状病毒表达系统在昆虫细胞中进行了特性分析。编码第444位氨基酸由亮氨酸替换为脯氨酸（L444P）的突变DNA的表达，在L444P/L444P纯合子的成纤维细胞或昆虫细胞中产生了一种催化缺陷且不稳定的酸性β-葡萄糖苷酶。该突变在亚急性神经病变型（3型）戈谢病中被发现是纯合等位基因。相比之下，编码第415位氨基酸由脯氨酸替换为精氨酸（P415R）的突变cDNA在昆虫细胞中的表达产生了一种无活性且不稳定的蛋白质。该等位基因仅在一名具有L444P/P415R基因型的2型患者中被发现。3型表型（L444P纯合子）的显著差异表明戈谢病表型变异分子基础的复杂性。然而，神经病变表型与产生严重受损（L444P）或功能缺失（P415R）酶的等位基因之间的关联表明，溶酶体中残余活性的有效水平可能是戈谢病严重程度 的主要决定因素。
