Endocytosis is not required for the selective lipid uptake mediated by murine SR-BI

TJF Nieland, M Ehrlich, M Krieger… - Biochimica et Biophysica …, 2005 - Elsevier
TJF Nieland, M Ehrlich, M Krieger, T Kirchhausen
Biochimica et Biophysica Acta (BBA)-Molecular and Cell Biology of Lipids, 2005Elsevier
The scavenger receptor class B, type I (SR-BI) mediates the cellular selective uptake of
cholesteryl esters and other lipids from high-density lipoproteins (HDL) and low-density
lipoproteins (LDL). This process, unlike classical receptor-mediated endocytosis, does not
result in lipoprotein degradation. Instead, the lipid depleted particles are released into the
medium. Here we show that selective lipid uptake mediated by murine SR-BI can be
uncoupled from the endocytosis of HDL or LDL particles. We found that blocking selective …
The scavenger receptor class B, type I (SR-BI) mediates the cellular selective uptake of cholesteryl esters and other lipids from high-density lipoproteins (HDL) and low-density lipoproteins (LDL). This process, unlike classical receptor-mediated endocytosis, does not result in lipoprotein degradation. Instead, the lipid depleted particles are released into the medium. Here we show that selective lipid uptake mediated by murine SR-BI can be uncoupled from the endocytosis of HDL or LDL particles. We found that blocking selective lipid uptake by incubating cells with the small chemical inhibitors BLT-1 or BLT-4 did not affect endocytosis of HDL. Similarly, blocking endocytosis by hyperosmotic sucrose or K+ depletion did not prevent selective lipid uptake from HDL or LDL. These findings suggest that mSR-BI-mediated selective uptake occurs at the cell surface upon the association of lipoproteins with mSR-BI and does not require endocytosis of HDL or LDL particles.
Elsevier