Intracellular processing of apo(a) in primary baboon hepatocytes

Ann L. White, David L. Rainwater, James E. Hixson, Larry E. Estlack, Robert E. Lanford

    Research output: Contribution to journalArticle

    24 Scopus citations

    Abstract

    We have developed a serum-free medium for the long-term culture of highly differentiated primary baboon hepatocytes. Hepatocytes isolated from animals with defined plasma Lp(a) levels and apo(a) glycoprotein phenotypes were used to study the assembly of Lp(a). A combination of steady-state and pulse-chase labeling studies and endoglycosidase digests demonstrated that apo(a) was synthesized as a lower molecular weight precursor. After a prolonged period of time in the endoplasmic reticulum, apo(a) was converted to a mature form and secreted. A proportion of mature apo(a) also had a prolonged residence time in the trans Golgi apparatus. In all experiments, apoB coimmunoprecipitated with apo(a) from the culture medium but not from the cell lysates, supporting an extracellular association of the proteins for the formation of Lp(a). Analysis of hepatic RNA from 29 'null' Lp(a) phenotype baboons revealed that one-third of the animals had detectable apo(a) transcripts, whereas the remainder had no detectable apo(a) mRNA. The baboon hepatocyte system therefore represents a valuable model to examine the effect of allelic variation at the apo(a) locus on Lp(a) assembly.

    Original languageEnglish (US)
    Pages (from-to)123-133
    Number of pages11
    JournalChemistry and Physics of Lipids
    Volume67-68
    Issue numberC
    DOIs
    StatePublished - Jan 1994

    Keywords

    • Endoplasmic reticulum
    • Golgi
    • Lipoprotein(a)
    • Primary hepatocytes

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Organic Chemistry
    • Cell Biology

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