Proteomics of brain from a myeloid specific NPC1 KO mouse

Niemann-Pick type C (NPC) disease is an inherited lysosomal storage disorder mainly driven by mutations in NPC1 gene, causing lipid accumulation within late endosomes/lysosomes, and resulting in progressive neurodegeneration. Although microglial activation proceeds neuronal loss, it remains elusive whether loss of NPC1 in microglia actively contributes to NPC pathology. Here, we used a mouse model with depletion of NPC1 in myeloid cells to investigate the role of microglia in Niemann-Pick disease. In order to achieve the loss of NPC1 in myeloid cells, mice with floxed Npc1 alleles (Npc1 flox/flox) were crossed with mice expressing the constitutively active Cre recombinase under the myeloid-specific promotor of Cx3cr1. Hyperactive microglia initiated a pathological cascade resembling NPC-like phenotypes, including shortened lifespan, motor impairments, astrogliosis, neuroaxonal pathology and increased levels of neuronal injury biomarker NF-L. To study the differential vulnerability between the brain regions, we compared the cerebellar with the cerebral (brain without cerebellum) proteome in Cre- and Cre+ mice at late pathological stages. Our results suggest that microglial loss of NPC1 has profound effects on brain cell homeostasis especially in the cerebrum.