Abstract
Esterified cholesterol (EC) accumulation was induced in THP-1 macrophages after exposure to acetylated LDL (acLDL), and the extent of accumulation was dependent on cell density. EC mass was 5-fold greater in cells plated at 1.0 x 10(6) cells/35 mm dish compared to cells plated at density 4.0 x 10(6) cells/dish. In addition, [14C]oleate incorporation into EC also increased with decreasing cell number, with 4-fold greater incorporation (6 h: 177 +/- 0.014 vs. 45 +/- 0.001 pmol/mg cell protein, P < 0.001; 24 h: 515 +/- 0.037 vs. 120 +/- 0.012 pmol/mg, P < 0.001) in cells plated less densely compared to cells plated at a higher density. The rate of 125I-labeled acLDL degradation was about 2-fold greater in cells plated at the lower density (105 vs. 60 ng/h per mg cell protein). Northern analysis showed a 2-fold reduction in the expression of human scavenger receptor mRNA in density plated cells, and immunoprecipitation also demonstrated a 2-fold decrease in scavenger receptor protein. Conditioned media did not differentially affect EC formation at either cell density. Fatty acid supplementation increased EC formation and the proportion of esterified sterol content only in cell plated at the higher density. The fatty acid effect was also seen when cells were exposed to beta-VLDL, which induced comparable levels of EC accumulation by non-scavenger receptor-mediated processes in densely plated cells. Foam cell formation in THP-1 macrophages may depend on cell density, which appears to affect both scavenger and non-scavenger receptor activity.
Highlights
0.001) in cells plated less densely compared to cells plated at a higher density
We found that cellular esterified cholesterol (EC) accumulation in response to acetylated low density lipoprotein (LDL) may depend upon cell density; EC mass increased 5-fold at the lowest density compared to cells plated at the higher density
O u r first aim was to induce EC accumulation in THP-1 cells exposed to acetylated LDL (acLDL)
Summary
0.001) in cells plated less densely compared to cells plated at a higher density. The rate of '*5I-labeled acLDL degradation was about 2-fold greater in cells plated at the lower density (105 vs. 60 ng/h per mg cell protein). We found that cellular EC accumulation in response to acetylated LDL may depend upon cell density; EC mass increased 5-fold at the lowest density compared to cells plated at the higher density. This results, in part, from differences in scavenger receptor expression and acLDL degradation as a function of cell density. Both scavenger receptor activity and the Abbreviations: acLDL, acetylated LDL; LDL, low density lipoprotein; VLDL, very low density lipoprotein; EC, esterified cholesterol; UC, unesterified cholesterol; PMA, phorbol myristate acetate; H M M , human monocyte macrophages.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.