Scavenger receptor, Class B, Type I provides an alternative means for beta-VLDL uptake independent of the LDL receptor in tissue culture

Clemens Röhrl, Stefanie Fruhwürth, Sabine Maria Schreier, Alfred Lohninger, Andrea Dolischka, Manfred Hüttinger, Nina Zemann, Marcela Hermann, Witta Strobl, Herbert Stangl

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Recent evidence suggests that scavenger receptor, class B, type I (SR-BI) plays a physiological role in VLDL metabolism. SR-BI was reported to mediate beta-VLDL uptake; however, cellular details of this process are not well characterized. In the present study we show that SR-BI delivers cholesterol derived from beta-VLDL to LDL receptor negative SR-BI over-expressing Chinese Hamster Ovarian cells (ldlA7-SRBI). Cell association of beta-VLDL was approximately 3 times higher after SR-BI over-expression, which was competed by beta-VLDL, but only to a lesser extent by HDL and LDL. Almost all of the associated beta-VLDL was located intracellularly, and therefore could not be released by a 50-fold excess of unlabeled beta-VLDL. beta-VLDL was degraded at a rate of 6 ng beta-VLDL/mg cell protein and hour. In contrast to ldlA7 cells, beta-VLDL association was competed by LDL in cells with a functional LDL receptor like CHO and HepG2 cells, indicating a strong impact of the LDL receptor in beta-VLDL uptake. beta-VLDL degradation was similar to ldlA7-SRBI cells. When beta-VLDL uptake was followed using fluorescence microscopy, beta-VLDL showed a different uptake pattern in SR-BI over-expressing cells, ldlA7-SRBI, compared to LDL receptor containing cells, CHO and HepG2.

Original languageEnglish
Pages (from-to)198-204
Number of pages7
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume1801
Issue number2
DOIs
Publication statusPublished - Feb 2010
Externally publishedYes

Keywords

  • β-VLDL
  • Chinese Hamster Ovarian Cells
  • Cholesterol
  • Chylomicrons
  • HepG2
  • LDL receptor
  • SR-BI
  • Cricetinae
  • Receptors, LDL/physiology
  • Cricetulus
  • Humans
  • Hep G2 Cells
  • Lipoproteins, IDL/metabolism
  • Animals
  • Lipids/analysis
  • CD36 Antigens/metabolism
  • CHO Cells

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