Loss of Flot2 expression in deep cerebellar nuclei neurons of mice with Niemann-Pick disease type C
Tsu-I Chen,
Pei-Chun Hsu,
Ni-Chung Lee,
Yu-Han Liu,
Hao-Chun Wang,
Yen-Hsu Lu,
Yin-Hsiu Chien,
Wuh-Liang Hwu
Affiliations
Tsu-I Chen
Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
Pei-Chun Hsu
Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
Ni-Chung Lee
Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
Yu-Han Liu
Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
Hao-Chun Wang
Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
Yen-Hsu Lu
Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan
Yin-Hsiu Chien
Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
Wuh-Liang Hwu
Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institute of Integrated Medicine, China Medical University, Taichung City, Taiwan; Corresponding author. Department of Pediatrics, National Taiwan University Hospital 8 Chung-Shan South Road, Taipei 10041, Taiwan.
Niemann-Pick disease type C (NPC) is caused by a deficiency of the NPC1 or NPC2 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 Npc1 knockout mice (Npc1-). We first demonstrated that DCN neurons of Npc1- 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 Camk1d, encoding one of the Ca2+/calmodulin-dependent protein kinases (CaMKs), increased in expression. We treated Npc1- mice with CaMK inhibitor KN-93, but CaMK1D expression increased further. We also fed Npc1- 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 Npc1- mice, GM2 sequestration and the loss of lipid rafts lead to cell dysfunction and symptoms of NPC.
