Determination of the lower threshold of apolipoprotein E resulting in remnant lipoprotein clearance

Alyssa H. Hasty, MacRae F. Linton, Larry L. Swift, Sergio Fazio

    Research output: Contribution to journalArticle

    57 Scopus citations

    Abstract

    Apolipoprotein E (apoE) is the ligand for receptor-mediated clearance of remnant lipoproteins. ApoE at concentrations only 10% of normal, achieved through transplantation of wild-type marrow into apoE(-/-) mice, is sufficient for the maintenance of normal serum lipid and lipoprotein levels. The goal of the present study was to identify the minimal concentration of serum apoE still affecting cholesterol levels, and to determine whether any effects on remnant clearance below this level of apoE were detectable. ApoE(+/+) marrow was mixed with apoE(-/-) marrow in proportions of 1, 5, 10, and 25% to make chimeric mice with serum levels of apoE ranging from 0.005 to 0.46 mg/dl. Analysis of serum cholesterol and apoE levels demonstrated a positive correlation between apoE levels and cholesterol reduction (r = 0.83), with levels of 0.04 mg/dl representing the functional threshold level. There were no differences in lipoprotein profiles and clearance between apoE(-/-) mice and mice with serum apoE of less than 0.04 mg/dl, as assessed by FPLC, non-denaturing gel electrophoresis, and turnover studies. However, electron microscopy of negative stains showed fewer lipoprotein particles with a diameter of <30 nm in the serum of these mice compared to apoE(-/-) mice. These data demonstrate that the threshold of serum apoE resulting in cholesterol reduction is 0.04 mg/dl, and indicate that apoE below this level affects lipoprotein size distribution possibly by accelerating the clearance of smaller remnants.

    Original languageEnglish (US)
    Pages (from-to)1529-1538
    Number of pages10
    JournalJournal of lipid research
    Volume40
    Issue number8
    StatePublished - Aug 1 1999

      Fingerprint

    Keywords

    • Apolipoprotein E
    • Bone marrow transplantation
    • Cholesterol
    • Remnant lipoproteins

    ASJC Scopus subject areas

    • Biochemistry
    • Endocrinology
    • Cell Biology

    Cite this