The new obesity-associated protein, neuronal growth regulator 1 (NEGR1), is implicated in Niemann-Pick disease Type C (NPC2)-mediated cholesterol trafficking.

Neuronal growth regulator 1 (NEGR1) is a newly identified raft-associated protein, which has recently been spotlighted as a new locus related to human obesity. Niemann-Pick disease Type C2 (NPC2) protein functions as a key player in the intracellular cholesterol trafficking, and its defect is linked to a fatal human neurodegenerative disease, NPC. In this study, we identified that NEGR1 interacts with NPC2 and increases its protein stability. Ectopically expressed NEGR1 proteins relieved an abnormal cholesterol accumulation in endosomal compartments. Importantly, NEGR1-defective mouse embryonic fibroblast cells exhibit increased cholesterol levels and triglyceride contents. These findings provide the first insight into the role of NEGR1 in intracellular cholesterol homeostasis, possibly explaining the missing link between NEGR1 with human obesity.