Recombinant Mouse G-protein coupled receptor 183 (Gpr183)

What is Recombinant Mouse Gpr183 and what are its basic specifications?

Recombinant Mouse Gpr183 is a G-protein coupled receptor expressed as either a full-length or partial-length protein. It belongs to the rhodopsin family and is widely expressed in B cells, T cells, and dendritic cells, where it regulates positioning and migration of immune cells within secondary lymphoid organs .

The recombinant protein is typically produced in mammalian cell expression systems with the following specifications:

• Source: Mammalian cells

• Tag: Often includes a His-tag for purification

• Form: Available as liquid or lyophilized powder

• Purity: Generally >80%

• Endotoxin: <1.0 EU per μg of protein (as determined by LAL method)

• Storage buffer: Phosphate-buffered saline (PBS)

• Storage conditions: +4°C for short-term storage; -20°C to -80°C for long-term storage

What genomic and sequence information is available for Mouse Gpr183?

Mouse Gpr183 has been well-characterized at the genomic level with the following parameters:

This genomic information is essential for designing experiments that involve genetic manipulation of Gpr183, including the creation of knockout models or expression vectors .

What are the primary biological functions of Gpr183 in the immune system?

Gpr183 plays several critical roles in the immune system:

• Regulation of immune cell positioning and migration within secondary lymphoid organs, which is crucial for proper immune response development

• Antagonism of chemokine-mediated B cell migration, as evidenced by transwell migration assays using recombinant CXCL12 as a chemoattractant. Studies show that Gpr183 inhibition or knockout significantly impacts cell mobility and migration patterns

• Modulation of F-actin polymerization, which affects immune cell movement and function. Research demonstrates that the absence or pharmacological blockade of Gpr183 counteracts decreases in F-actin polymerization typically observed in certain therapeutic contexts

• Mediation of interactions between immune cells, particularly in the context of macrophage recruitment and activation. Experimental evidence shows that knockout or inhibition of Gpr183 abrogates macrophage infiltration in tumor models

Understanding these functions is essential for researchers designing experiments to investigate immune responses, particularly in the context of lymphoid tissue development and organization.

How is Gpr183 expression regulated in different cell types?

Gpr183 exhibits distinct expression patterns across immune cell populations:

• Highest expression is observed in dendritic cells (DCs), with approximately 42% of conventional DCs and 37% of plasmacytoid DCs showing positive expression

• B cells and CD4+ T cells also express Gpr183, but at lower frequencies compared to DCs

• Expression in monocytes is more sporadic and variable across different monocyte subpopulations

• Expression patterns vary in response to stimuli, as demonstrated in vaccination studies where Gpr183 exhibited complex response patterns that differed with each dose

These cell type-specific expression patterns suggest that Gpr183 may have distinct roles in different immune cell populations, warranting cell-specific approaches when designing experiments to study its function.

What are the optimal storage and handling conditions for Recombinant Mouse Gpr183?

For optimal activity and stability of Recombinant Mouse Gpr183:

• Short-term storage: Maintain at +4°C for up to one week

• Long-term storage: Store at -20°C to -80°C, preferably in small aliquots to avoid repeated freeze-thaw cycles

• Buffer conditions: The protein is typically stable in PBS buffer, but specific applications may require optimization of buffer composition

• Handling precautions: Minimize exposure to room temperature and avoid repeated freeze-thaw cycles as these can lead to protein denaturation and loss of activity

• Reconstitution of lyophilized material: When working with lyophilized preparations, reconstitute using sterile buffer, preferably filtered to maintain sterility

Following these guidelines will help maintain the structural integrity and functional activity of the recombinant protein for experimental applications.

What methods are effective for Gpr183 knockout or inhibition studies?

Researchers have successfully employed several approaches to study Gpr183 function through knockout or inhibition:

• CRISPR/Cas9 gene editing: This has been successfully used to generate Gpr183 knockout cell lines (e.g., Raji-GPR183 KO single-clones). These genetic models allow for comprehensive assessment of Gpr183 function in cellular processes

• Pharmacological inhibition: The selective Gpr183 inhibitor NIBR189 has been effectively used in experimental setups. Typically, cells are exposed to NIBR189 for a defined period (e.g., 1 hour), followed by wash-out before proceeding with functional assays

• Validation of knockout/inhibition: Researchers should confirm the efficacy of knockout or inhibition through:

  • Western blot analysis for protein expression

  • Functional assays such as chemotaxis or cell migration assays

  • Verification of downstream signaling pathway alterations

• Phenotypic characterization: Complete assessment should include analysis of:

  • Cell migration capabilities (using transwell assays)

  • F-actin polymerization (which can be decreased by ~70% in certain contexts upon Gpr183 deletion)

  • Inflammatory gene expression profiles

  • Cell-cell interaction dynamics

These methods provide complementary approaches to investigate Gpr183 function in various biological contexts.

How does Gpr183 contribute to tumor recognition and immune response in cancer models?

Gpr183 plays a crucial role in tumor recognition and immune response in cancer models, particularly in B-cell malignancies:

• Macrophage infiltration and activation: Studies with Raji-GPR183 knockout models demonstrated that Gpr183 is essential for macrophage infiltration into tumor spheroids. Absence of Gpr183 resulted in complete abrogation of macrophage infiltration within multicellular aggregates, both at basal levels and in response to therapeutic interventions

• Antibody-dependent cellular phagocytosis (ADCP): Research shows that ADCP activity is severely compromised in Gpr183-knockout cell cultures, highlighting the critical role of Gpr183 in macrophage recruitment and activation after therapeutic targeting of cancer cells

• Antibody-dependent cellular cytotoxicity (ADCC): While ADCC is also affected by Gpr183 knockout, the impact is less profound compared to ADCP, suggesting differential regulation of these immune effector mechanisms

• Inflammatory signaling: Gpr183 is required for the induction of inflammatory gene signatures, particularly CCL20 overexpression, which further contributes to anti-tumor immune responses

• In vivo relevance: Gpr183 knockout models showed resistance to anti-tumor therapies in chorioallantoic membrane (CAM) tumor models, with no modulation of CCL20 expression and failed intratumoral infiltration of macrophages

These findings suggest that Gpr183 status could be an important consideration in the design of immunotherapeutic approaches for B-cell malignancies.

What is the significance of the MX2/GPR183 ratiometric transcript signature in immune response studies?

The MX2/GPR183 ratiometric transcript signature has emerged as an important biomarker in immune response studies:

• Predictive value: This signature has been consistently associated with protection in vaccine studies. Logistic regression models incorporating the MX2/GPR183 ratio demonstrated significant discriminatory power between protected and non-protected individuals following vaccination

• Complex expression dynamics: While MX2 tends to be induced 24 hours after vaccination, GPR183 exhibits a more complex expression pattern that differs with each dose. Generally, lower GPR183 levels were observed in volunteers who would ultimately be protected

• Correlation with protein levels: Analyses of tumor tissue proteogenomic data revealed that GPR183 transcript levels correlate significantly with GPR183 protein levels, including various phosphorylated forms (e.g., S343, S328, S333, S337), suggesting that transcript measurements provide meaningful insight into protein activity

• Potential mechanistic interpretation: Reduced blood GPR183 RNA levels in protected individuals may reflect enhanced migration of GPR183-expressing cells to lymphoid tissues, potentially leading to more robust adaptive immune responses

• Complementarity with other markers: The MX2/GPR183 ratio provides complementary information to traditional markers such as anti-CSP titers, potentially enhancing the predictive power of immune response assessments

This signature represents a valuable tool for researchers studying immune responses, particularly in vaccine development and evaluation contexts.

What are common challenges in working with Recombinant Mouse Gpr183 and how can they be addressed?

Researchers working with Recombinant Mouse Gpr183 may encounter several technical challenges:

• Protein stability and activity:

  • Challenge: Loss of activity during storage or experimental manipulation

  • Solution: Maintain strict temperature control, minimize freeze-thaw cycles, and consider adding stabilizing agents such as glycerol or bovine serum albumin to storage buffers

• Expression system considerations:

  • Challenge: Variations in post-translational modifications depending on the expression system

  • Solution: For studies requiring specific post-translational modifications, select mammalian expression systems that closely mimic natural processing

• Functional assays:

  • Challenge: Determining appropriate readouts for Gpr183 activity

  • Solution: Consider multiple complementary assays, including chemotaxis, F-actin polymerization, and downstream signaling pathway activation

• Specificity of inhibitors:

  • Challenge: Potential off-target effects of pharmacological inhibitors

  • Solution: Validate results using genetic approaches (e.g., CRISPR/Cas9 knockout) in parallel with pharmacological inhibition

• Interpretation of complex expression patterns:

  • Challenge: Gpr183 exhibits complex expression dynamics that vary by cell type and stimulus

  • Solution: Perform single-cell analyses (e.g., flow cytometry or single-cell RNA-Seq) to resolve cell type-specific responses

Addressing these challenges requires careful experimental design and appropriate controls to ensure reliable and reproducible results.

How can researchers validate the functional activity of Recombinant Mouse Gpr183 preparations?

Validating the functional activity of Recombinant Mouse Gpr183 preparations is crucial for experimental success:

• Binding assays:

  • Ligand binding assays using known Gpr183 ligands

  • Competition assays with known Gpr183 antagonists such as NIBR189

• Signaling pathway activation:

  • Assessment of downstream signaling components

  • Measurement of second messenger production (e.g., calcium flux, cAMP levels)

• Functional cellular assays:

  • Chemotaxis assays using transwell migration systems with CXCL12 as a chemoattractant

  • F-actin polymerization assays, which can serve as a readout for Gpr183 activity

• Comparative analysis:

  • Side-by-side comparison with established reference standards

  • Benchmarking against published data on dose-response relationships

• Positive and negative controls:

  • Inclusion of Gpr183 knockout cells as negative controls

  • Use of pharmacological inhibitors (e.g., NIBR189) to confirm specificity of observed effects

A multi-faceted approach to validation ensures that experimental observations truly reflect Gpr183 function rather than artifacts or non-specific effects.

What emerging research areas involve Recombinant Mouse Gpr183?

Several promising research directions are emerging for Recombinant Mouse Gpr183:

• Post-translational regulation mechanisms:

  • Investigation of phosphorylation sites (S343, S328, S333, S337) and their functional significance

  • Assessment of how phosphorylation status affects Gpr183 activity and signaling

• Cell type-specific functions:

  • Detailed characterization of Gpr183 functions in different immune cell populations

  • Use of conditional knockout models to delineate cell-specific roles

• Role in immunotherapeutic approaches:

  • Exploration of Gpr183 as a potential target or biomarker for cancer immunotherapy

  • Development of strategies to modulate Gpr183 activity to enhance anti-tumor immune responses

• Vaccine response biomarkers:

  • Further validation of the MX2/GPR183 ratio as a predictive biomarker for vaccine efficacy

  • Integration with other immune parameters to develop comprehensive response prediction models

• Single-cell analyses:

  • Application of single-cell RNA-Seq or flow cytometry to resolve cell type-specific Gpr183 expression patterns

  • Investigation of heterogeneity in Gpr183 expression and function within nominally homogeneous cell populations

These emerging areas represent significant opportunities for researchers to contribute to the understanding of Gpr183 biology and its potential clinical applications.

How might Gpr183 research contribute to therapeutic development in immune-related diseases?

Gpr183 research holds significant potential for therapeutic development in immune-related diseases:

• Cancer immunotherapy:

  • Gpr183 modulation could enhance macrophage infiltration and phagocytic activity against tumor cells

  • Combination approaches targeting Gpr183 alongside established immunotherapeutic agents might improve efficacy

• Inflammatory disorders:

  • Given Gpr183's role in immune cell positioning and migration, targeting this receptor may help control aberrant inflammatory responses

  • Gpr183 antagonists could potentially reduce inflammatory cytokine production in conditions characterized by excessive inflammation

• Vaccine development:

  • Understanding Gpr183's role in vaccine responses could inform the design of more effective vaccination strategies

  • The MX2/GPR183 ratio could serve as a biomarker to predict and monitor vaccine efficacy

• B-cell malignancies:

  • Targeting Gpr183 may enhance the efficacy of existing therapies for B-cell lymphomas and leukemias

  • Gpr183 status assessment could help stratify patients for specific therapeutic approaches

• Targeted drug delivery:

  • Knowledge of Gpr183 expression patterns could be leveraged to develop targeted drug delivery systems specific to Gpr183-expressing cells

These potential therapeutic applications underscore the importance of continued basic and translational research on Gpr183 biology and function.