Department of Psychology, Section of Neuroscience and "Daniel Bovet" Neurobiology Research Center, Sapienza University of Rome, Via dei Sardi 70, 00185, Rome, Italy.
IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, 00179, Rome, Italy.
Acta Neuropathol Commun. 2016 Sep 1;4(1):94. doi: 10.1186/s40478-016-0370-z.
Niemann-Pick type C1 (NPC1) disease is a lysosomal storage disorder caused by defective intracellular trafficking of exogenous cholesterol. Purkinje cell (PC) degeneration is the main sign of cerebellar dysfunction in both NPC1 patients and animal models. It has been recently shown that a significant decrease in Sonic hedgehog (Shh) expression reduces the proliferative potential of granule neuron precursors in the developing cerebellum of Npc1 (-/-) mice. Pursuing the hypothesis that this developmental defect translates into functional impairments, we have assayed Npc1-deficient pups belonging to the milder mutant mouse strain Npc1 (nmf164) for sensorimotor development from postnatal day (PN) 3 to PN21. Npc1 (nmf164) / Npc1 (nmf164) pups displayed a 2.5-day delay in the acquisition of complex motor abilities compared to wild-type (wt) littermates, in agreement with the significant disorganization of cerebellar cortex cytoarchitecture observed between PN11 and PN15. Compared to wt, Npc1 (nmf164) homozygous mice exhibited a poorer morphological differentiation of Bergmann glia (BG), as indicated by thicker radial shafts and less elaborate reticular pattern of lateral processes. Also BG functional development was defective, as indicated by the significant reduction in GLAST and Glutamine synthetase expression. A reduced VGluT2 and GAD65 expression also indicated an overall derangement of the glutamatergic/GABAergic stimulation that PCs receive by climbing/parallel fibers and basket/stellate cells, respectively. Lastly, Npc1-deficiency also affected oligodendrocyte differentiation as indicated by the strong reduction of myelin basic protein. Two sequential 2-hydroxypropyl-β-cyclodextrin administrations at PN4 and PN7 counteract these defects, partially preventing functional impairment of BG and fully restoring the normal patterns of glutamatergic/GABAergic stimulation to PCs.These findings indicate that in Npc1 (nmf164) homozygous mice the derangement of synaptic connectivity and dysmyelination during cerebellar morphogenesis largely anticipate motor deficits that are typically observed during adulthood.
尼曼-皮克 C1 型（NPC1）病是一种溶酶体贮积症，由外源性胆固醇的细胞内转运缺陷引起。浦肯野细胞（PC）退化是 NPC1 患者和动物模型中小脑功能障碍的主要标志。最近的研究表明，Sonic hedgehog（Shh）表达的显著降低会降低 Npc1（-/-）小鼠发育中小脑颗粒神经元前体细胞的增殖潜能。我们推测这种发育缺陷会转化为功能障碍，因此，我们检测了来自轻度突变小鼠株 Npc1（nmf164）的 NPC1 缺陷型幼鼠，从出生后第 3 天（PN）到第 21 天（PN）的感觉运动发育情况。与野生型（wt）同窝仔相比，Npc1（nmf164）/Npc1（nmf164）幼鼠在获得复杂运动能力方面延迟了 2.5 天，这与在 PN11 和 PN15 之间观察到的小脑皮质细胞结构明显紊乱一致。与 wt 相比，Npc1（nmf164）纯合子小鼠的 Bergmann 胶质（BG）形态分化较差，表现为径向轴更粗，外侧过程的网状模式不发达。此外，BG 功能发育也存在缺陷，表现为 GLAST 和谷氨酰胺合成酶表达显著减少。VGluT2 和 GAD65 表达减少也表明，PC 分别通过 climbing/parallel fibers 和 basket/stellate cells 接收的谷氨酸能/GABA 能刺激的整体紊乱。最后，NPC1 缺陷也影响少突胶质细胞分化，表现为髓鞘碱性蛋白的强烈减少。在 PN4 和 PN7 时进行两次连续的 2-羟丙基-β-环糊精处理，可以部分抵消这些缺陷，完全恢复正常的谷氨酸能/GABA 能刺激到 PC。这些发现表明，在 Npc1（nmf164）纯合子小鼠中，小脑形态发生过程中突触连接的紊乱和脱髓鞘现象在成年期通常观察到的运动缺陷之前就已经出现。
