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Published on: September 25, 2019
Control of Mac-2 surface expression on murine macrophage cell lines
1National Institute for Medical Research, London, UK.
European Journal of Immunology
|January 1, 1994
Summary
Immature macrophages (WEHI-3 cells) synthesize Mac-2 antigen but fail to secrete it, unlike mature macrophages. This suggests secretion, not synthesis, regulates Mac-2 levels and offers a system to study non-classical protein secretion.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Mac-2 antigen is a murine macrophage cell-surface protein belonging to the soluble galactoside-binding lectin family.
- Mac-2 expression levels can indicate macrophage differentiation status.
- Previous studies established a differentiation sequence for murine macrophage cell lines based on surface markers, including Mac-2.
Purpose of the Study:
- To investigate the regulation of Mac-2 antigen expression at the protein secretion level in macrophage cell lines.
- To characterize the secretion defect of Mac-2 in immature WEHI-3 macrophage cells.
- To establish WEHI-3 cells as a model system for studying the non-classical secretion pathway of Mac-2.
Main Methods:
- Comparing Mac-2 antigen synthesis and secretion in WEHI-3 (immature) versus J774.2 and P388.D1 (mature) macrophage cell lines.
- Assessing Mac-2 binding to WEHI-3 cells and the expression of Mac-2-binding carbohydrates using plant lectins.
- Evaluating the effect of calcium ionophore A23187 on Mac-2 secretion in different macrophage cell lines.
Main Results:
- WEHI-3 cells synthesize Mac-2 antigen similarly to mature macrophage cell lines but do not secrete it.
- Exogenous Mac-2 binds effectively to WEHI-3 cells, indicating functional Mac-2 receptors or binding sites.
- Putative Mac-2-binding carbohydrates are equally expressed across WEHI-3, J774.2, and P388.D1 cells.
- Calcium ionophore A23187 did not significantly enhance Mac-2 secretion in WEHI-3 cells.
Conclusions:
- Mac-2 antigen expression in macrophage cell lines is regulated at the level of protein secretion, not solely by synthesis.
- WEHI-3 cells exhibit a specific defect in Mac-2 secretion, making them a valuable model for studying intracellular transport and non-classical secretion pathways.
- Mac-2 secretion is independent of classical secretory pathways as the protein lacks a signal sequence.
