Related Experiment Videos
Low affinity Fc gamma receptors on murine macrophages: mitogen-activated protein kinase activation and AP-1 DNA
M J Cote-Vélez1, E Ortega, A Ortega
1Departamento de Genética y Biología Molecular Centro de Investagacion y de Estudios Avanzados del IPN 2508, C.P. México, Mexico.
Abstract:
Mouse macrophage cell lines such as J774 express Fc receptors for IgG2a immune complexes, which upon binding of the proper ligand, trigger several signal transduction pathways. A surface to nucleus signaling through these receptors has been demonstrated. We describe here the activation of the mitogen-activated protein kinase (MAPK) and an increase in the binding of the activator protein 1 (AP-1) to DNA upon receptor stimulation. The described effects are only partially blocked by inhibitors of the Ca2+/diacylglycerol-dependent protein kinase (PKC), suggesting that differential signaling pathways are activated upon receptor cross-linking and that they converge at or above the MAPK level. These results pave the way to our understanding of Fc gammaR cross-linking induced gene expression regulation.
Insights
Mouse macrophages activate signaling pathways upon Fc receptor stimulation, leading to increased mitogen-activated protein kinase (MAPK) and activator protein 1 (AP-1) DNA binding. These findings illuminate Fc gamma receptor cross-linking in gene expression regulation.
Area of Science:
- Immunology
- Cell Signaling
- Molecular Biology
Background:
- Mouse macrophage cell lines like J774 possess Fc receptors for IgG2a immune complexes.
- Fc receptor engagement initiates signal transduction pathways from the cell surface to the nucleus.
Purpose of the Study:
- To investigate the specific signaling pathways activated by Fc gamma receptor (FcγR) cross-linking in macrophages.
- To elucidate the role of protein kinase C (PKC) in FcγR-mediated signaling.
Main Methods:
- Stimulation of J774 macrophage cell lines with IgG2a immune complexes.
- Analysis of mitogen-activated protein kinase (MAPK) activation.
- Assessment of activator protein 1 (AP-1) DNA binding activity.
- Inhibition studies using protein kinase C (PKC) inhibitors.
Main Results:
- FcγR stimulation activates MAPK signaling.
- AP-1 DNA binding increases significantly upon FcγR cross-linking.
- PKC inhibition only partially blocks these signaling events, indicating parallel pathways.
Conclusions:
- FcγR cross-linking triggers distinct signaling cascades that converge at or upstream of the MAPK pathway.
- These pathways are crucial for FcγR-mediated gene expression regulation in macrophages.