Studies on the β-galactosidosis using transgenic mice expressing ganglioside-related glycogenes

β-半乳糖糖苷病包括临床不同的疾病，gm1 -神经节脂质病和Morquio B病，两者都是由于溶酶体酸β-半乳糖糖苷酶（β-Gal）缺乏引起的。我们的研究重点是gm1神经节脂质病，这是一种主要发生在婴儿早期的神经遗传性疾病，很少发生在儿童或青年。在本研究中，我们建立了幼年gm1神经节脂质病模型小鼠，在β-Gal KO背景下表达一种突变酶蛋白R201C。模型小鼠从9月龄开始出现缓慢进行性神经退化，如震颤和步态障碍，并在15月龄左右死亡。与β-Gal小鼠相比，小鼠大脑中神经节苷脂GM1的储存量较少。用这只老鼠，我们检验了化学伴侣疗法的可能性。新合成的β-Gal抑制剂口服gm1神经节脂质沉积幼年模型小鼠，可显著增强脑及其他组织的酶活性。尽管在这项短期试验（1周）中，大量生化分析并未显示大脑中GM1的减少，但化学伴侣疗法可能对某些GM1神经节脂质沉积症和其他可能累及中枢神经系统的溶酶体贮积症患者有用。我们还制备了表达GM1/GA1合成酶基因的转基因小鼠，并试图将转基因小鼠导入β-Gal KO小鼠，以加速其发病。我们将含有CAG启动子和小鼠GM1/GA1合成酶cDNA的3.5 kb转基因片段（1.2 kb）注射到C57BL/6J小鼠的受精卵细胞中。我们培育了4种转基因小鼠，至少在肝脏和大脑中表达了这种转基因。在3个转基因小鼠的肝脏中检测到GM1，而在非转基因C57BL/6小鼠中未检测到GM1。我们目前正在通过将转基因引入β-Gal KO小鼠，评估GM1/GA1合成酶过表达对疾病发病的影响。

β-Galactosidosis comprises clinically different diseases, GM1-gangliosidosis and Morquio B disease, both of which are caused by deficiency of lysosomal acid β-galactosidase (β-Gal). We focused on GM1-gangliosidosis, a neurogenetic disease occurring mainly in early infancy, and rarely in childhood or young adults. In this study, we generated the model mouse of juvenile GM1-gangliosidosis, expressing a mutant enzyme protein R201C on the β-Gal KO background. The model mice exhibited slowly progressive neurological deterioration, such as tremor and gait disturbance from 9 months of age and died around 15 months. Storage of ganglioside GM1 in their brains was less abundant than in the β-Gal KO mouse brain. Using this mouse, we examined the possibility of chemical chaperone therapy. Oral administration of newly synthesized β-Gal inhibitor to the juvenile GM1-gangliosidosis model mice resulted in significant enhancement of the enzyme activity in the brain and other tissues. Although mass biochemical analysis did not show the reduction of GM1 in the brain in this short term trial (1 week), chemical chaperone therapy may be useful for certain patients with GM1-gangliosidosis and potentially other lysosomal storage diseases with central nervous system involvement. We also generated the transgenic mice expressing GM1/GA1 synthase gene and tried to introduce the transgene into β-Gal KO mice in order to accelerate their disease onset. We injected the transgene fragments (3.5 kb) containing CAG promoter and mouse GM1/GA1 synthase cDNA (1.2 kb) into fertilized oocytes of C57BL/6J mice. We produced 4 lines of transgenic mice expressing the transgene at least in the liver and the brain. GM1 was detected in the liver of 3 transgenic mouse lines, although no GM1 was detectable in non-transgenic C57BL/6 mice. We are currently evaluating the effect of the over expression of GM1/GA1 synthase on the disease onset by introducing the transgene into β-Gal KO mice.