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Induction of a prenylated 65-kd protein in macrophages by interferon or lipopolysaccharide
D J Vestal1, R A Maki, J E Buss
1La Jolla Cancer Research Foundation, California 92037, USA.
Abstract:
Treatment of murine bone marrow-derived macrophages with interferon-gamma (IFN-gamma) and/or lipopolysaccharide (LPS) resulted in changes in the abundance of a number of prenylated proteins. The most significant change involved a protein of 65 kd (p65) that became one of the most abundant prenylated proteins following treatment. The 65-kd protein was induced by agents that stimulate macrophage activation (IFNs or LPS) but not by cytokines that promote macrophage proliferation, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), M-CSF, or interleukin-3. The majority of p65 was localized to subcellular fractions containing internal and plasma membranes but was not detected in nuclear membranes. The farnesyltransferase inhibitor BZA-5B caused a dramatic decrease in p65 prenylation, suggesting that this protein may be modified by the C15 isoprenoid farnesyl. These observations provide the first direct evidence that interferons and LPS cause changes in the abundance of specific isoprenoid-modified proteins in macrophages.
Insights
Interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) alter prenylated protein levels in macrophages. A 65-kd protein (p65) significantly increases, indicating a novel link between macrophage activation and protein prenylation.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Macrophage activation is crucial for immune responses.
- Prenylated proteins play vital roles in cellular processes.
- Understanding molecular changes during macrophage activation is key.
Purpose of the Study:
- To investigate the impact of interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) on prenylated proteins in macrophages.
- To identify specific prenylated proteins affected by macrophage activation stimuli.
Main Methods:
- Murine bone marrow-derived macrophages were treated with IFN-gamma and/or LPS.
- Changes in prenylated protein abundance were analyzed.
- Subcellular localization and prenylation inhibition studies were performed.
Main Results:
- Treatment with IFN-gamma or LPS significantly altered the abundance of several prenylated proteins.
- A 65-kd protein (p65) emerged as a highly abundant prenylated protein post-treatment.
- p65 was induced by macrophage activation agents but not proliferation cytokines.
- p65 localized to internal and plasma membranes, and its prenylation was inhibited by BZA-5B, suggesting farnesyl modification.
Conclusions:
- IFN-gamma and LPS induce significant changes in specific prenylated proteins within macrophages.
- The 65-kd protein (p65) is a novel, prominently prenylated protein upregulated during macrophage activation.
- This study provides the first direct evidence linking macrophage activation stimuli to alterations in isoprenoid-modified proteins.