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Selective induction of the beta chemokine C10 by IL-4 in mouse macrophages
A Orlofsky1, E Y Lin, M B Prystowsky
1Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461.
Insights
The study reveals distinct regulation of the beta chemokine C10 compared to other chemokines like MIP-1 alpha, JE, and RANTES. Unlike others, C10 expression is not induced by LPS but is upregulated by cytokines IL-3, GM-CSF, and IL-4.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Beta chemokines are small proteins that attract leukocytes.
- Their regulation is crucial for immune responses.
- C10 is a newly identified beta chemokine with unknown function.
Purpose of the Study:
- To investigate the expression and regulation of the murine beta chemokine C10.
- To compare C10 regulation with other beta chemokines (MIP-1 alpha, JE, RANTES).
- To elucidate the role of cytokines and inhibitors in C10 expression.
Main Methods:
- Primary macrophages (BMM and RPM) were cultured.
- Cells were stimulated with LPS, IL-3, GM-CSF, IL-4, and cycloheximide.
- Gene expression was analyzed via mRNA levels.
- Protein accumulation was measured in culture supernatants.
Main Results:
- LPS did not induce C10 expression in any macrophage type.
- IL-3 and GM-CSF strongly induced C10 in both BMM and RPM.
- IL-4 dose-dependently induced C10 in BMM and RPM.
- C10 expression required de novo protein synthesis, unlike other chemokines.
Conclusions:
- C10 exhibits unique regulatory patterns compared to other beta chemokines.
- Its distinct regulation suggests specialized functions in host defense.
- Cytokine signaling pathways differentially control beta chemokine expression.
Abstract:
The beta chemokines are a family of 8- to 12-kDa leukocyte chemoattractants that are typically produced by activated macrophages or lymphocytes. We examined the expression in primary macrophages of a recently described, and as yet functionally uncharacterized, murine beta chemokine, C10, and contrasted its regulation with that of several other beta chemokines. Although three other beta chemokines, macrophage inflammatory protein-1 alpha (MIP-1 alpha), JE, and RANTES, were all induced by LPS treatment of bone marrow-derived macrophages (BMM) and/or resident peritoneal macrophages (RPM), LPS stimulation of C10 was never observed. Conversely, IL-3 and granulocyte macrophage-CSF (GM-CSF) strongly induced C10 in both macrophage populations, whereas MIP-1 alpha and RANTES showed a weaker induction restricted to BMM. JE was strongly induced but only in BMM. Finally, IL-4 strongly induced C10 in a dose-dependent manner in both BMM and RPM but failed to stimulate any of the other three beta chemokines. The accumulation of C10 protein in culture supernatants paralleled the induction of mRNA, and the combination of IL-4 and GM-CSF led to enhanced protein levels. The expression of the C10 message in response to cytokines was completely blocked by cycloheximide, whereas the other three chemokines were all overexpressed in the presence of this inhibitor. These results demonstrate a sharp divergence between the regulation of C10 expression and that of other chemokines and suggest that this molecule may have distinct functions in host defense.