Loss of Flot2 expression in deep cerebellar nuclei neurons of mice with Niemann-Pick disease type C.

Niemann-Pick disease type C (NPC) is caused by a deficiency of the or gene, leading to storages of unesterified cholesterol and sphingolipids. Cerebellar ataxia is a main symptom of NPC and the deep cerebellar nuclei (DCN) is the sole signal output of the cerebellum. In this study, we explored the pathological changes in DCN neurons of knockout mice (). We first demonstrated that DCN neurons of mice had prominent ganglioside GM2 accumulation in the late endosomes but not in the lysosomes. More importantly, Flot2 expression, a marker for the lipid rafts, was lost. Single-nucleus RNA sequencing analysis revealed a generalized reduction in gene expression in DCN neurons, though , encoding one of the Ca/calmodulin-dependent protein kinases (CaMKs), increased in expression. We treated mice with CaMK inhibitor KN-93, but CaMK1D expression increased further. We also fed mice with two medications for NPC. We found that miglustat, a sphingolipid synthesis inhibitor, increased the expression of Flot2. Moreover, N-acetyl l-leucine (NALL), an experimental medicine for NPC, recovered Flot2 expression. Therefore, our data suggest that in mice, GM2 sequestration and the loss of lipid rafts lead to cell dysfunction and symptoms of NPC.