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MIP-3alpha induces human eosinophil migration and activation of the mitogen-activated protein kinases (p42/p44 MAPK)
S K Sullivan1, D A McGrath, F Liao
1Department of Immunology, Neurocrine Biosciences Inc., San Diego, California 92121, USA.
Abstract:
The CC chemokine macrophage inflammatory protein-3alpha (MIP-3alpha) is the product of recent electronic cloning efforts, however, little characterization of its spectrum of biological effects has been undertaken. Human eosinophils exhibited pertussis-toxin-sensitive migration in response to human recombinant (hr)MIP-3alpha. Messenger RNA for the MIP-3alpha receptor, CCR-6, and low levels of surface expression were demonstrated by reverse transcriptase-polymerase chain reaction and FACS analysis. Analyses of cell signaling revealed dose-dependent increases in intracellular calcium mobilization, calcium transients that were, however, greatly reduced when compared with MCP-3-induced responses. Further investigations of MIP-3alpha-induced signal transduction revealed time- and dose-dependent, partially pertussis toxin-dependent, increases in phosphorylation of the p42/p44 mitogen-activated protein kinases (MAPK) that occurred at 10- to 100-fold lower concentrations, and that were linked to a phosphoinositide 3-kinase pathway. These results suggest that MIP-3alpha can regulate multiple, parallel signal transduction pathways in eosinophils, and suggest that MAPK activation by MIP-3alpha in eosinophils is a significant signaling pathway for migration induction.
Insights
Macrophage inflammatory protein-3alpha (MIP-3alpha) induces human eosinophil migration via pertussis-toxin-sensitive pathways. MIP-3alpha activates mitogen-activated protein kinases (MAPK) and phosphoinositide 3-kinase signaling in eosinophils.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophage inflammatory protein-3alpha (MIP-3alpha) is a CC chemokine with incompletely characterized biological effects.
- Eosinophils play a role in inflammatory and allergic responses.
Purpose of the Study:
- To characterize the biological effects of MIP-3alpha on human eosinophils.
- To investigate the signaling pathways involved in MIP-3alpha-induced eosinophil responses.
Main Methods:
- Human eosinophils were used to assess migration in response to MIP-3alpha.
- Reverse transcriptase-polymerase chain reaction (RT-PCR) and FACS analysis were employed to detect MIP-3alpha receptor (CCR-6) expression.
- Intracellular calcium mobilization and mitogen-activated protein kinase (MAPK) phosphorylation were measured to analyze signal transduction.
Main Results:
- Human eosinophils demonstrated MIP-3alpha-induced, pertussis-toxin-sensitive migration.
- CCR-6 mRNA and surface expression were detected on eosinophils.
- MIP-3alpha induced dose-dependent increases in intracellular calcium and MAPK phosphorylation, linked to phosphoinositide 3-kinase (PI3K) pathway.
Conclusions:
- MIP-3alpha regulates multiple signaling pathways in eosinophils, including calcium mobilization and PI3K.
- MAPK activation by MIP-3alpha is a significant pathway for inducing eosinophil migration.