Recombinant Human C-C chemokine receptor type 6 (CCR6)

What is Recombinant Human C-C Chemokine Receptor Type 6 (CCR6)?

Recombinant Human C-C Chemokine Receptor Type 6 (CCR6) is a member of the G protein-coupled receptor family that primarily functions as a chemokine receptor. CCR6 is expressed in lymphocytes (both CD4 and CD8 T cells and B cells), but notably absent in natural killer cells, monocytes, and granulocytes . It has been identified as selectively expressed in human dendritic cells derived from CD34+ cord blood precursors but not in dendritic cells derived from peripheral blood monocytes . CCR6 plays a significant role in mediating the migration of inflammatory and regulatory T cells and regulating central nervous system (CNS) inflammation .

How does CCR6 function in the immune system?

CCR6 serves as a critical regulator of immune cell trafficking, particularly for dendritic cells and specific T cell subsets. The receptor facilitates chemotaxis in response to its ligands, enabling directed cell migration during immune responses. In dendritic cells, CCR6 contributes to their migratory behavior from tissues to lymphoid organs for antigen presentation to lymphocytes . This migration is essential for initiating immune responses. CCR6 also plays a role in the homeostasis of immune cells in lymphoid tissues and regulates inflammatory responses in various tissues, including the CNS .

What are the primary ligands for CCR6?

Among the various chemokines tested, macrophage inflammatory protein 3α (MIP-3α) has shown the strongest interaction with CCR6 . Unlike many other chemokine receptors that interact with multiple ligands, CCR6 demonstrates a high degree of specificity. When CCR6 is stably expressed as a recombinant protein in different host cell backgrounds, it shows strong interaction with only MIP-3α among 25 chemokines tested . This selective binding profile makes CCR6 particularly valuable for studying specific chemokine-receptor interactions in immune regulation.

What experimental models are suitable for studying CCR6 function?

The BXD recombinant inbred (RI) mouse strain model has proven valuable for studying CCR6 function, particularly in the context of neuroinflammation. Research utilizing 31 C57BL/6J X DBA/2J (BXD) RI mouse strains and their parental strains under different treatment conditions has provided significant insights into CCR6 expression and regulation . This model allows researchers to investigate how genetic background influences CCR6 expression and function.

Experimental design for CCR6 studies should include:

What techniques are recommended for measuring CCR6 expression?

For comprehensive analysis of CCR6 expression, multiple complementary techniques should be employed:

• RNA-seq provides a robust quantification of Ccr6 transcript abundance, allowing for genome-wide correlation analysis with other genes .

• RT-qPCR enables validation of expression changes and precise quantification of Ccr6 mRNA levels.

• Western blotting can confirm changes in protein expression.

• Immunohistochemistry allows visualization of CCR6 expression in specific cell types within tissues.

• Flow cytometry enables quantification of CCR6 expression on specific immune cell populations.

When analyzing expression data, researchers should consider both fold-change and statistical significance. In the CORT+DFP mouse model of Gulf War Illness, Ccr6 expression decreased 1.6-fold (p < 0.0001) in the prefrontal cortex compared to control conditions .

How does CCR6 contribute to neuroinflammatory responses?

CCR6 has been identified as a candidate gene underlying individual differences in susceptibility to Gulf War Illness (GWI), a condition associated with neuroinflammation . The gene is cis-regulated, meaning its expression is controlled by nearby genetic elements. Its expression is significantly correlated with corticosterone plus diisopropylfluorophosphate (CORT+DFP) treatment, which models aspects of GWI .

Correlation analysis has revealed 1473 Ccr6-correlated genes (p < 0.05) in the CORT+DFP treatment group, with significant enrichment in immune, inflammation, cytokine, and neurological-related categories . This indicates CCR6 functions within a broader network of genes involved in neuroinflammatory responses. Five CNS-related phenotypes and fecal corticosterone concentration have also shown significant correlation (p < 0.05) with Ccr6 expression in the prefrontal cortex .

What is the relationship between CCR6 and dendritic cell function?

Dendritic cells (DCs) initiate immune responses by transporting antigens from tissues to lymphoid organs for presentation to lymphocytes. CCR6 appears to be selectively expressed in human dendritic cells derived from CD34+ cord blood precursors, but not in dendritic cells derived from peripheral blood monocytes . This selective expression pattern suggests CCR6 may regulate specific subsets of dendritic cells.

Chemokines regulate the migration of DCs, with certain CC chemokines acting as chemoattractants for some DC types in vitro . CCR6 likely contributes to this migratory behavior, influencing DC trafficking between tissues and lymphoid organs. This makes CCR6 a potentially important target for modulating immune responses initiated by DCs.

How do genetic variations affect CCR6 function?

The response of Ccr6 to CORT+DFP treatment differs significantly (p < 0.0001) between parental strains in the BXD mouse model, indicating that Ccr6 expression and function are affected by host genetic background . This genetic influence contributes to individual differences in susceptibility to conditions involving CCR6-mediated responses.

Gene set enrichment analysis of Ccr6-correlated genes has identified relevant pathways and biological processes. In the CORT+DFP treatment group, 47 significantly enriched GO terms (FDR < 0.05) and 23 KEGG pathways (FDR < 0.05) were identified, particularly highlighting immune, inflammation, and cytokine-related functions . This network analysis provides insight into how CCR6 interacts with G protein-coupled receptors, the kallikrein-kinin system, and neuroactive ligand-receptors.

What are best practices for protein-protein interaction studies involving CCR6?

For studying CCR6 protein interactions, the following methodological approach is recommended:

• Utilize the STRING database to identify known and predicted protein-protein interactions (PPIs).

• Extract target gene lists with high confidence interaction scores (minimum 0.9 recommended).

• Apply Markov Cluster Algorithm (MCL) clustering for subnetwork construction.

• Perform GO and KEGG pathway analysis on the subnetwork genes to understand biological functions.

This approach has successfully identified interaction networks for Ccr6-correlated genes in neuroinflammation models . The resulting networks provide insights into how CCR6 participates in broader signaling cascades and functional pathways.

How can researchers effectively design experiments to study CCR6 in disease models?

When designing experiments to study CCR6 in disease models, researchers should consider:

• Include multiple timepoints to capture dynamic changes in CCR6 expression and function. For GWI models, it's recommended to assess Ccr6 mRNA levels at later time points in chronic models to verify its potential as a disease marker .

• Account for disease heterogeneity by including diverse genetic backgrounds (e.g., multiple mouse strains).

• Consider both gene expression and protein-level analyses to comprehensively assess CCR6 involvement.

• Incorporate behavioral phenotyping to correlate CCR6 function with disease manifestations.

• Evaluate related genes such as Tnf-α, Il6, Il1β, and Spon1, which may also be involved in CCR6-related disease processes like neuroinflammation .

What statistical approaches are most appropriate for analyzing CCR6-related datasets?

For robust analysis of CCR6-related data, the following statistical approaches are recommended:

• Pearson product-moment correlation analysis for identifying Ccr6-correlated genes and phenotypes. This approach has successfully identified 1473 genes significantly correlated (p < 0.05) with Ccr6 in the CORT+DFP group .

• Apply Benjamini and Hochberg correction for multiple comparisons when performing gene set enrichment analysis.

• Set appropriate thresholds for significance (typically FDR < 0.05) and minimum gene overlap (minimum of 5 genes recommended) .

• For treatment comparisons, calculate fold change and apply appropriate statistical tests (t-tests or ANOVA depending on the experimental design).

• For correlation with phenotypes, consider both statistical significance and effect size to identify biologically relevant associations.

What are promising therapeutic applications targeting CCR6?

CCR6 has been identified as a promising therapeutic target for conditions involving neuroinflammation, such as Gulf War Illness . In humans, CCR6 mediates the migration of inflammatory and regulatory T cells and regulates CNS inflammation, suggesting potential applications in treating neuroinflammatory disorders .

Research should focus on:

• Developing specific CCR6 antagonists or modulators

• Investigating the effects of CCR6 modulation on dendritic cell migration and function

• Examining how targeting CCR6 affects broader inflammatory networks

• Evaluating the therapeutic potential in animal models before clinical translation

How might CCR6 research contribute to understanding broader immune regulation?

The study of CCR6 provides insights into the molecular mechanisms controlling dendritic cell migration and function, which are central to immune response initiation . Understanding how chemokines like MIP-3α interact with CCR6 to guide dendritic cell trafficking could illuminate fundamental principles of immune regulation.

The polymorphisms of Ccr6 and synergistic interactions with related G protein-coupled receptors, the kallikrein-kinin system, and neuroactive ligand-receptors likely contribute to the heterogeneity and complexity of immune-related disorders . Further research in this area may help explain individual variations in immune responses and susceptibility to inflammatory conditions.