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Published on: March 21, 2014
Expression of functional formyl peptide receptors by human astrocytoma cell lines
1Laboratory of Molecular Immunoregulation, Division of Basic Sciences, National Cancer Institute, Frederick Cancer Research and Development Center, 21702-1201, Frederick, MD, USA.
Abstract:
Activation of astrocytes is important in the pathogenesis of a variety of diseases in the central nervous system, such as infection and neurodegeneration. We found that the bacterial chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLF) induced potent migration and Ca(2+) mobilization in human astrocytoma cell lines. The effect of fMLF was pertussis toxin-sensitive, suggesting the involvement of seven transmembrane, G protein-coupled receptor(s) for fMLF. Scatchard analyses revealed that astrocytoma cell lines express both high- and low-affinity binding sites for [3H]fMLF. RT-PCR confirmed the expression of transcripts of fMLF receptors, the high-affinity FPR and the low-affinity FPRL1 by these cells. Both fMLF and F peptide, a synthetic peptide domain of HIV-1 envelope protein which specifically activates FPRL1, increased secretion of IL-6 by astrocytoma cells. Our study demonstrates for the first time that FPR and FPRL1 expressed by astrocytoma cell lines are functional, and suggests a molecular basis for the involvement of these receptors in host defense in the brain.
Insights
Human astrocytoma cells respond to bacterial peptides like N-formyl-methionyl-leucyl-phenylalanine (fMLF) by migrating and releasing inflammatory signals. These responses are mediated by functional FPR and FPRL1 receptors, suggesting a role in brain defense.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Astrocyte activation is implicated in central nervous system diseases, including neurodegeneration and infection.
- The bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (fMLF) is known to interact with specific receptors.
Purpose of the Study:
- To investigate the functional expression and signaling of fMLF receptors in human astrocytoma cell lines.
- To explore the role of these receptors in cellular responses relevant to brain pathogenesis and host defense.
Main Methods:
- Utilized human astrocytoma cell lines for experiments.
- Assessed cell migration and intracellular calcium (Ca2+) mobilization in response to fMLF.
- Performed pertussis toxin sensitivity assays and Scatchard analyses for receptor binding.
- Confirmed receptor gene expression using RT-PCR.
- Measured interleukin-6 (IL-6) secretion.
Main Results:
- fMLF induced significant migration and Ca2+ mobilization in astrocytoma cells, a response sensitive to pertussis toxin.
- Scatchard analysis indicated the presence of both high- and low-affinity fMLF binding sites.
- RT-PCR confirmed the expression of formyl peptide receptor (FPR) and FPR-like 1 (FPRL1) transcripts.
- Both fMLF and an FPRL1-specific peptide (F peptide) stimulated IL-6 secretion from astrocytoma cells.
Conclusions:
- Human astrocytoma cell lines express functional FPR and FPRL1 receptors.
- These receptors mediate cellular responses, including migration, Ca2+ signaling, and IL-6 release.
- The findings suggest a molecular mechanism for the involvement of FPR and FPRL1 in brain host defense and disease.
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