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Dietary myristic acid alters acylated proteins in activated murine macrophages
N E Hubbard1, R J Socolich, K L Erickson
1Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA 95616-8643, USA.
Abstract:
After stimulation with select activating agents such as lipopolysaccharide (LPS) or recombinant interferon-gamma (rIFNgamma), several macrophage proteins may be induced, acylated with myristic acid, or both. Our goal in this study was to determine whether altering the levels of myristic acid in the diet would modulate the levels of a specific acylated macrophage protein, MacMARCKS (myristoylated, alanine-rich C kinase substrate), because that fatty acid can be found in substantial quantities in some foods. Thioglycollate-elicited peritoneal macrophages from groups of mice fed diets with various levels of myristic acid (from 0.2 to 99 g/100 g fatty acids) were treated with LPS, phorbol myristate acetate (PMA), or rIFNgamma plus LPS, which are well-established macrophage activating agents. Levels of MacMARCKS were measured by enzyme-linked immunosorbent assay using a rabbit anti-mouse polyclonal antibody against the first 10 amino acids of murine MacMARCKS. A 42-kDa protein with the same molecular weight as MacMARCKS was identified in macrophage lysates by Western analysis using the antibody. Lipopolysaccharide- and PMA-activated macrophages from mice fed the trimyristin diet had significantly greater levels of MacMARCKS than LPS- and PMA-activated macrophages of mice fed the safflower oil-containing diet. The levels of MacMARCKS were also greater in lysates of LPS plus rIFNgamma-stimulated macrophages from mice fed the trimyristin diet and mice fed a diet containing a moderate level of myristic acid (12 g/100 g fatty acids) compared with the lysates of macrophages from mice fed the safflower oil diet. These results indicate that altering the level of myristic acid in the diet may alter the production of specific proteins that may be involved in macrophage activation.
Insights
Dietary myristic acid levels influence macrophage protein MacMARCKS. Higher myristic acid intake, particularly from trimyristin, increased MacMARCKS levels in activated macrophages, suggesting a link between diet and immune response modulation.
Area of Science:
- Immunology
- Nutrition Science
- Molecular Biology
Background:
- Macrophage activation involves protein induction and acylation.
- MacMARCKS (myristoylated, alanine-rich C kinase substrate) is a macrophage protein.
- Myristic acid is a dietary fatty acid found in various foods.
Purpose of the Study:
- To investigate if dietary myristic acid levels modulate MacMARCKS protein levels in macrophages.
- To understand the relationship between dietary fat composition and macrophage activation markers.
Main Methods:
- Mice were fed diets with varying myristic acid content.
- Peritoneal macrophages were isolated and stimulated with activating agents (LPS, PMA, rIFNgamma).
- MacMARCKS levels were quantified using ELISA and Western blot analysis.
Main Results:
- Macrophages from mice fed a high-myristic acid diet (trimyristin) showed significantly higher MacMARCKS levels after LPS or PMA stimulation.
- Increased MacMARCKS levels were also observed in LPS plus rIFNgamma-stimulated macrophages from mice on high- and moderate-myristic acid diets compared to controls.
- A 42-kDa protein consistent with MacMARCKS was identified in macrophage lysates.
Conclusions:
- Dietary myristic acid levels can alter the production of specific macrophage proteins like MacMARCKS.
- These findings suggest a dietary influence on macrophage activation pathways.
- Modulating dietary fat composition may impact immune cell function.