Intracellular cholesterol transport machinery

The intracellular cholesterol transport machinery is a coordinated system of proteins and lipids that regulates the movement of cholesterol between cellular organelles, such as the lysosomes, endoplasmic reticulum, and plasma membrane [PMID: 10430864]. Central to this process are the Niemann-Pick C1 (NPC1) and C2 (NPC2) proteins, which work in tandem to export unesterified cholesterol from the late endosomal/lysosomal compartment [PMID: 21866103]. Other components include oxysterol-binding proteins (OSBPs) and steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domain proteins, which facilitate non-vesicular transport at membrane contact sites [PMID: 25104354]. Defects in this machinery, particularly mutations in NPC1 or NPC2, lead to Niemann-Pick disease type C, a progressive neurodegenerative disorder characterized by the toxic accumulation of lipids [PMID: 21148116]. Furthermore, the NPC1 protein has been identified as an essential entry receptor for filoviruses, including Ebola and Marburg viruses, highlighting the machinery's role in infectious disease [PMID: 21866103]. Therapeutic interventions targeting this system include cyclodextrins to mobilize sequestered cholesterol and small-molecule inhibitors of specific transport proteins for antiviral or anticancer applications [PMID: 28793970, 25104354]. This machinery is also implicated in the pathogenesis of Alzheimer's disease and atherosclerosis, where cholesterol distribution affects amyloid processing and plaque formation, respectively [PMID: 19647133].

Other names

Cholesterol trafficking systemEndosomal cholesterol transport pathwayNPC pathwayIntracellular lipid transport machinery

Facilitation of lysosomal cholesterol egress, inhibition of non-vesicular lipid transfer at membrane contact sites, and modulation of viral entry via receptor binding.