Pathogenesis and Treatment of beta-Galactosidase-Deficient Knockout Mice

我们<M1>通过破坏鼠β-半乳糖苷酶基因成功地建立了人G_ -神经节苷脂沉积症的小鼠模型，以分析其发病机制并尝试治疗方法。临床上，突变小鼠在出生后4个月发展为进行性神经系统疾病，表现为痉挛性双侧瘫痪。他们在7-11个月大时死于严重的神经系统功能障碍和极度消瘦。在中枢神经系统的每个区域都观察到由于未消化底物的储存而引起的神经元胞质肿胀，并且储存物质在电子显微镜下表现为膜状胞质体。这种形态学变化在4 ~ 8周龄迅速进行。生化分析表明，神经节苷脂G_1及其<M1>脱唾液酸衍生物G_<A1>D在中枢神经系统和某些实体组织如肝、脾中有明显的贮存。与<A1>人类患者相比，G_储存更为显著。这些结果表明，该模型动物是人G_<M1>-神经节苷脂沉积症的真实小鼠模型。然而，在这些疾病小鼠中没有骨发育不良或硫酸尿角蛋白。尿低聚糖薄层层析异常，与婴儿G_<M1>-神经节苷脂沉积症相似。作为实验性试验，将腺病毒介导的β-半乳糖苷酶cDNA静脉内注射到突变新生小鼠中。注射后2周，在10%正常人乳头的中枢神经系统中有β-半乳糖苷酶活性表达。在这个阶段，与未经治疗的动物相比，G_<M1>和G_<A1>的储存显着减少。我们的结论是，在血管系统中引入的基因已经通过新生儿期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.