Scavenger receptor class B type I localizes to a late endosomal compartment

• Main Authors: Malika Ahras, Thet Naing, Ruth McPherson
• Format: Article
• Language: English
• Published: Elsevier 2008-07-01
• Series: Journal of Lipid Research
• Subjects: cholesterol; selective uptake; late endosomes; lysosomes; intracellular trafficking
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520347283

Scavenger receptor class B type I (SR-BI) has an established role in mediating the selective uptake of cholesterol from HDL in hepatocytes, steroidogenic cells, and other tissues. SR-BI is present on the plasma membrane but also localizes to stable intracellular compartments of unknown function. Using indirect immunofluorescence and subcellular fractionation, we have investigated the subcellular distribution of SR-BI. We report that red fluorescent protein-tagged mouse SR-BI (RFP-mSR-BI) colocalizes with the late endosomal and lysosomal markers, Rab7, LBPA, and Rab9. In addition, endogenous SR-BI is also found on lysosomes and colocalizes with LAMP-2 in primary hepatocytes. Furthermore, we demonstrate that the trafficking of SR-BI through these compartments is Rab7 dependent. Interestingly, filipin staining indicates accumulation of lysosomal cholesterol in SR-BI-deficient (−/−) as compared with wild-type hepatocytes. In addition to its role as a plasma membrane receptor, SR-BI may function in cholesterol trafficking from late endosomes/lysosomes.