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Isolation of Murine Peritoneal Macrophages to Carry Out Gene Expression Analysis Upon Toll-like Receptors Stimulation
Published on: April 29, 2015
IL-4 inhibits expression of the formyl peptide receptor gene in mouse peritoneal macrophages
Yalei Dai1, Jennifer Major, Michael Novotny
1Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Abstract:
Regulation of leukocyte recruitment is an important determinant of the host response to microbial infection. Because tissue infiltration by inflammatory cells represents a potential source of unnecessary tissue damage, the process may be controlled by modulating the expression of chemoattractants and the receptors through which they promote directed leukocyte migration. In the present report, we show that expression of the receptor for chemotactic formylated peptides (FPR1)is negatively regulated in both macrophages and neutrophils by interleukin-4 (IL-4). The reduction of FPR1 mRNA occurs rapidly in response to both IL-4 and IL-13 but endures for <4 h after the removal of IL-4. As with many other responses to IL-4 and IL-13, suppression of FPR1 expression is dependent on the activation of Stat6. The inhibitory effect exhibits relative stimulus specificity in that other Stat-activating cytokines, such as interferon-gamma (IFN-gamma), IFN-beta, and IL-10, have no effect. Using nuclear run-on analysis, the rate of FPR1 gene transcription is high but is not suppressed by IL-4. Moreover, IL-4 does not appear to alter the rate of FPR mRNA decay. Nevertheless, FPR mRNA exhibits a short half-life (< or =2 h), and this appears to be a critical feature of the ability of IL-4 to reduce expression. Taken together, the data suggest that IL-4 and IL-13 suppress the expression of FPR1 mRNA via a mechanism that operates to eliminate primary transcripts prior to maturation and depends on the constitutive instability of preexisiting mRNA.
Insights
Interleukin-4 (IL-4) and IL-13 reduce the expression of the formylated peptide receptor 1 (FPR1) in immune cells. This regulation, dependent on Stat6 activation, impacts leukocyte recruitment during infection.
Area of Science:
- Immunology
- Molecular Biology
- Cellular Signaling
Background:
- Leukocyte recruitment is crucial for host defense against infection.
- Uncontrolled inflammatory cell infiltration can cause tissue damage.
- Modulating chemoattractant receptor expression is a key regulatory mechanism.
Purpose of the Study:
- To investigate the regulation of formylated peptide receptor 1 (FPR1) expression by cytokines.
- To determine the role of interleukin-4 (IL-4) and IL-13 in FPR1 regulation.
- To elucidate the molecular mechanisms underlying IL-4-mediated suppression of FPR1.
Main Methods:
- Analysis of FPR1 mRNA levels in macrophages and neutrophils.
- Treatment with IL-4, IL-13, and other cytokines (IFN-gamma, IFN-beta, IL-10).
- Nuclear run-on assays to assess gene transcription.
- Assessment of mRNA decay rates.
- Investigation of Stat6 activation.
Main Results:
- IL-4 and IL-13 rapidly suppress FPR1 mRNA expression in macrophages and neutrophils.
- Suppression is dependent on Stat6 activation and specific to IL-4/IL-13.
- IL-4 does not affect FPR1 gene transcription or mRNA decay rate.
- FPR1 mRNA has a short half-life, contributing to rapid expression changes.
Conclusions:
- IL-4 and IL-13 negatively regulate FPR1 expression via a post-transcriptional mechanism.
- This regulation involves the elimination of primary transcripts before maturation.
- The constitutive instability of FPR1 mRNA is critical for IL-4's suppressive effect.
- This finding provides insights into controlling leukocyte migration during infection.
