Pathogenesis and Treatment of beta-Galactosidase-Deficient Knockout Mice

我们成功地通过破坏鼠蛋白-半乳糖苷酶基因建立了人G_<M1>-神经节脂质沉积症小鼠模型，以分析其发病机制并尝试治疗方法。在临床上，突变小鼠在出生后4个月出现进行性神经系统疾病，表现为痉挛性双瘫。它们在7-11个月大时死于严重的神经系统功能障碍和极度消瘦。在中枢神经系统各部位均可见未消化底物的储存引起的神经元细胞质肿胀，电镜下可见储存物质为膜质细胞质体。这种形态变化在4 ~ 8周龄之间迅速发展。在所有被检查的组织和体液中，-半乳糖苷酶活性几乎完全缺乏。生化分析显示，神经节苷脂G_<M1>及其亚洲植物衍生物G_<A1>D在中枢神经系统和肝脏、脾脏等实体组织中有明显的储存。与人类患者相比，G_<A1>储存更为显著。这些结果表明，该模型动物是人类G_<M1>-神经节脂质沉积症的真实小鼠对应物。然而，在这些疾病小鼠中没有骨发育不良或角蛋白硫尿。尿寡糖薄层色谱显示异常模式，与婴儿G_<M1>-神经节脂质病相似。作为一项实验试验，腺病毒介导的β -半乳糖苷酶cDNA静脉注射进入突变新生小鼠。注射后2周中枢神经系统β -半乳糖苷酶活性以10%正常水平表达。在此阶段，与未处理的动物相比，G_<M1>和G_<A1>的储存量显著降低。我们的结论是，在新生儿期引入血管系统的基因通过未发育的血脑屏障到达中枢神经系统。

We succeeded in producing a mouse model of human G_<M1>-gangliosidosis by disruption of the murin beta-galactosidase gene, in order to analyze its pathogenesis and to try therapeutic approaches. Clinically the mutant mouse developed a progressive neurological disease 4 months after birth, manifesting itself as spastic diplegia. They died of severe nervous system dysfunction and extreme emaciation at 7-11 months of age. Neuronal cytoplasmic swelling due to storage of undigested substrates was observed in every area of the central nervous system, and the storage material appeared as membranous cytoplasmic bodies electron microscopically. This morphological change progerssed rapidly between 4 and 8 weeks of age. beta-Galactosidase activity was almost compeltely deficient in all tissues and body fluids examined.Biochemical analysis revealed a marked storage of ganglioside G_<M1> and its asialo derivative G_<A1>D in the central nervous system and some solid tissues, such as liver and spleen. G_<A1> storage was more remarkable as compared to that in human patients. These results indicated that this model animal is an authentic murine counterpart of human G_<M1>-gangliosidosis. However, there was no bone dysplasia or keratan sulfaturia in these disease mice. Urinary oligosaccharides showed an abnormal pattern on thin-layr chromatography which was similar to that in infantile G_<M1>-gangliosidosis. As an experimental trial, an adenovirus-mediated intravenous injection of beta-galactosidase cDNA was preformed into the mutant newborn mouse. The beta-galactosidase activity was expressed in the central nervous system 2 weeks after injection at the 10% normal lavel. At this stage, storage of G_<M1> and G_<A1> was significantly reduced as compared to animals without treatment. We concluded that the gene introduced in the vascular system has reached the central nervous system through the undeveloped blood-brain barrier in the neonatal period.