TY - JOUR
T1 - Endocytosis is not required for the selective lipid uptake mediated by murine SR-BI
AU - Nieland, Thomas J.F.
AU - Ehrlich, Marcelo
AU - Krieger, Monty
AU - Kirchhausen, Tomas
N1 - Funding Information:
We thank Marsha Penman, Shangzhe Xu, and Yu Zhu for excellent technical assistance; Karen Kozarsky for generously providing the KKB-1 antibody; Bernd Schimmer and David Williams for providing Y1-BS1 cells; members of the Kirchhausen and Krieger labs for helpful discussion; and the Harvard Institute of Chemistry and Cell Biology (ICCB) for support. This work was supported by National Institutes of Health Grants HL48739, HL66105 and HL52212 HL48739 to MK, and GM62566 to TK.
PY - 2005/5/1
Y1 - 2005/5/1
N2 - 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.
AB - 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.
KW - BLT
KW - Endocytosis
KW - High-density lipoprotein
KW - Low-density lipoprotein
KW - Scavenger receptor
KW - Scavenger receptor class B, type I
UR - http://www.scopus.com/inward/record.url?scp=18144424371&partnerID=8YFLogxK
U2 - 10.1016/j.bbalip.2005.02.007
DO - 10.1016/j.bbalip.2005.02.007
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AN - SCOPUS:18144424371
SN - 1388-1981
VL - 1734
SP - 44
EP - 51
JO - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
JF - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
IS - 1
ER -