GO:0071750 dimeric IgA immunoglobulin complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0071750 describes the dimeric IgA immunoglobulin complex, a secreted antibody complex of two IgA monomers linked by disulfide bonds and a J chain bridge.
• Dimeric IgA is the main mucosal antibody, transported across epithelia by the polymeric immunoglobulin receptor (pIgR).
• The J chain is essential for polymerization and for efficient secretion of dimeric IgA.
• Defects in dimeric IgA production or transport are linked to mucosal infections and inflammatory conditions such as cystic fibrosis lung disease.
• Selective IgA deficiency is the most common primary immunodeficiency and highlights the clinical importance of IgA complexes.
• CRISPR-based knockout, knock-in, and overexpression models enable functional dissection of dimeric IgA assembly and transcytosis.
Description
The dimeric IgA immunoglobulin complex (GO:0071750) is a secreted protein complex composed of two monomeric IgA antibodies covalently linked by disulfide bonds and bridged by a single J chain molecule. Each IgA monomer contains two identical IgA heavy chains and two identical light chains, and the dimer can further associate with the secretory component during epithelial transcytosis. This complex is the predominant immunoglobulin in mucosal secretions and plays a central role in immune exclusion of pathogens at mucosal surfaces. Understanding its assembly, transport, and regulation is therefore critical for mucosal immunology and vaccine research. Researchers study dimeric IgA using genetic models, biochemical assays, and imaging to define how its components cooperate in host defense.
dimeric IgA immunoglobulin complex At A Glance
| GO ID | GO:0071750 |
|---|---|
| GO term | dimeric IgA immunoglobulin complex |
| Ontology | cellular_component |
| Synonym | dimeric IgA1 antibody; dimeric IgA antibody |
| Major function | Mucosal immune defense and antigen neutralization |
| Composition | Two IgA monomers, two light chains each, one J chain |
| Localization | Extracellular space, mucosal areas, blood, lymph |
| Associated receptor | Polymeric immunoglobulin receptor (pIgR) |
| Clinical relevance | Mucosal infections, IgA deficiency, cystic fibrosis |
What Is GO:0071750?
According to the Gene Ontology, GO:0071750 refers to a protein complex made of two monomeric IgA immunoglobulin complexes joined by direct disulfide bonds and by a disulfide-bonded J chain that acts as a bridge. Each IgA monomer consists of two identical IgA heavy chains and two identical light chains held together by disulfide bonds. Dimeric IgA can also be complexed with secretory component and is found in the extracellular space, mucosal areas, other tissues, or circulating in blood or lymph.
Why Is dimeric IgA immunoglobulin complex Important in Cell Biology?
Dimeric IgA is the central effector of mucosal immunity, and its correct assembly and transport are required to protect mucosal surfaces from pathogens. Defects in dimeric IgA production or secretion are associated with recurrent infections and inflammatory diseases, including selective IgA deficiency and cystic fibrosis lung disease. Because dimeric IgA also contributes to immune exclusion and neutralization, it is a key target for vaccine and therapeutic development.
• Dimeric IgA is the predominant immunoglobulin in mucosal secretions and mediates immune exclusion.
• The J chain is required for efficient polymerization and secretion of dimeric IgA.
• pIgR-mediated transcytosis delivers dimeric IgA to mucosal surfaces.
• Selective IgA deficiency is the most common primary immunodeficiency.
• Cystic fibrosis is associated with dysregulated lung IgA immunity.
• Dimeric IgA can be complexed with secretory component in secretions.
• Bacterial and TLR signals can modulate IgA transcytosis.
• Aging affects IgA production by Peyer's patch B cells.
• Dimeric IgA is a target for mucosal vaccine design.
• CRISPR models enable functional studies of IgA assembly genes.
What Happens During dimeric IgA immunoglobulin complex?
Assembly of IgA monomers
In simple terms: Two IgA antibody units are built first.
Each IgA monomer consists of two identical IgA heavy chains and two identical light chains held together by disulfide bonds. These monomers are produced by plasma cells in mucosal tissues and then assemble into dimers.
J chain incorporation
In simple terms: A small J chain links the two IgA units together.
The J chain is incorporated into the dimer and forms disulfide bonds with both IgA monomers, acting as a bridge. MZB1 promotes the secretion of J-chain-containing dimeric IgA and is critical for suppression of gut inflammation.
Transcytosis by pIgR
In simple terms: The dimer is carried across epithelial cells to the mucosal surface.
The polymeric immunoglobulin receptor (pIgR) binds dimeric IgA and transports it across epithelial cells. Disulfide bond formation between dimeric IgA and pIgR occurs during hepatic transcytosis. Functional expression of pIgR has been demonstrated in fibroblasts.
Secretory component association
In simple terms: Part of the receptor stays attached to the dimer in secretions.
After transcytosis, a fragment of pIgR called the secretory component remains bound to dimeric IgA, forming secretory IgA. This complex is present in mucosal areas and extracellular fluids.
Regulation by bacteria and TLRs
In simple terms: Microbes and immune signals can change how much IgA is transported.
Bacteria and Toll-like receptor-dependent bacterial ligands have disparate effects on immunoglobulin A transcytosis. This regulation helps tune mucosal immune responses to the local microbial environment.
Key Genes Involved in GO:0071750 dimeric IgA immunoglobulin complex
The following genes and proteins are central to the assembly, transport, and regulation of the dimeric IgA immunoglobulin complex.
| Gene | Major Role | Research Relevance |
|---|---|---|
| IGHA1 | IgA1 heavy chain constant region | Forms the IgA monomer backbone |
| IGHA2 | IgA2 heavy chain constant region | Alternative IgA isotype in mucosal immunity |
| IGKC | Ig kappa light chain | Light chain component of IgA monomers |
| IGLC1 | Ig lambda light chain | Light chain component of IgA monomers |
| JCHAIN | J chain | Bridges IgA monomers into dimers |
| PIGR | Polymeric immunoglobulin receptor | Transports dimeric IgA across epithelia |
| MZB1 | Marginal zone B and plasma cell protein | Promotes secretion of J-chain-containing dimeric IgA |
| TNFRSF13B | TACI | Regulates IgA class switching |
| CD40 | B cell co-stimulation | Required for IgA production |
| AICDA | Activation-induced cytidine deaminase | Class switch recombination to IgA |
| PRDM1 | Blimp-1 | Plasma cell differentiation for IgA secretion |
| XBP1 | X-box binding protein 1 | Unfolded protein response in IgA plasma cells |
| IL10 | Interleukin 10 | Promotes IgA production |
| TGFB1 | Transforming growth factor beta 1 | Induces IgA class switching |
| CCL25 | CCL25 chemokine | Recruits IgA plasma cells to mucosa |
| MADCAM1 | Mucosal addressin cell adhesion molecule 1 | Homing of IgA plasma cells |
| RETNLB | Resistin-like beta | Mucosal immune regulation |
How Is dimeric IgA immunoglobulin complex Regulated?
Dimeric IgA assembly and secretion are regulated at multiple levels. MZB1 promotes the secretion of J-chain-containing dimeric IgA and is critical for suppression of gut inflammation. The polymeric immunoglobulin receptor (pIgR) is required for transcytosis, and its expression can be modulated by bacterial and TLR-dependent signals. Aging-associated intrinsic defects in IgA production by Peyer's patch B cells have been described. Additionally, cytokines such as IL-10 and TGF-beta influence IgA class switching and plasma cell differentiation.
dimeric IgA immunoglobulin complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| JCHAIN | Gut inflammation | Jchain knockout mouse |
| PIGR | Mucosal infection susceptibility | Pigr knockout mouse |
| MZB1 | Gut inflammation | Mzb1 knockout mouse |
| IGHA1 | Selective IgA deficiency | IgA knockout mouse |
| TNFRSF13B | Selective IgA deficiency | Tnfrsf13b knockout mouse |
Selective IgA deficiency
Selective IgA deficiency is the most common primary immunodeficiency, characterized by low serum IgA and increased susceptibility to mucosal infections. Defects in dimeric IgA assembly or secretion may contribute to the pathogenesis.
Cystic fibrosis lung disease
Lung immunoglobulin A immunity is dysregulated in cystic fibrosis, with altered dimeric IgA production and transport contributing to chronic airway inflammation. Understanding dimeric IgA biology may inform therapies for cystic fibrosis lung disease.
Gut inflammation
MZB1 deficiency impairs secretion of J-chain-containing dimeric IgA and leads to exacerbated gut inflammation. This highlights the role of dimeric IgA in maintaining intestinal homeostasis.
Mucosal infections
Dimeric IgA is essential for immune exclusion of pathogens at mucosal surfaces, and defects in its production or transport increase susceptibility to infections.
From dimeric IgA immunoglobulin complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does J chain loss impair dimeric IgA assembly? | Jchain knockout cell line |
| Does pIgR mutation affect transcytosis? | Pigr point-mutation knock-in |
| Can tagged IgA track secretion? | Knock-in of fluorescent tag on IgA heavy chain |
| Does MZB1 overexpression enhance IgA secretion? | MZB1 overexpression cell line |
| Does IgA deficiency alter mucosal immunity? | IgA knockout mouse |
| Does bacterial stimulation alter IgA transport? | In vitro transcytosis assay with TLR ligands |
How to Study the dimeric IgA immunoglobulin complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Non-reducing SDS-PAGE | Dimeric vs monomeric IgA | Assembly analysis |
| Co-immunoprecipitation | IgA-pIgR interaction | Transcytosis studies |
| Transcytosis assay | Epithelial transport | Mucosal immunity |
| Fluorescence microscopy | Intracellular trafficking | Live-cell imaging |
| CRISPR knockout | Gene function | Loss-of-function studies |
| CRISPR knock-in | Tagged protein expression | Tracking IgA |
| RNA-seq | Transcriptional changes | Pathway analysis |
| Proteomics | Protein composition | Complex characterization |
Biochemical analysis of dimeric IgA
Non-reducing SDS-PAGE and immunoblotting can resolve monomeric and dimeric IgA and detect J chain association. Disulfide bond formation between dimeric IgA and pIgR can be analyzed by co-immunoprecipitation.
Transcytosis assays
In vitro transcytosis assays using polarized epithelial cells measure the transport of dimeric IgA from the basolateral to apical side. This can be combined with bacterial or TLR ligand stimulation to study regulation.
Imaging of IgA complexes
Fluorescence microscopy and live-cell imaging can visualize the trafficking of dimeric IgA and pIgR in epithelial cells. Tagged IgA knock-in models enable real-time tracking.
Genetic screens
CRISPR library screening can identify genes required for dimeric IgA assembly and secretion. Bioinformatics analysis of transcriptomic data can reveal pathways co-regulated with IgA genes.
How CRISPR Can Be Used to Study GO:0071750 dimeric IgA immunoglobulin complex
Knockout
CRISPR knockout of JCHAIN, PIGR, or MZB1 can abolish dimeric IgA assembly or secretion, providing causal evidence for their roles. Knockout cell lines are useful for studying the consequences of loss of function in mucosal immunity.
Point Mutation
Point mutations can be introduced into disulfide bond-forming cysteines in IgA heavy chains or J chain to test their requirement for dimerization. Such models help dissect the precise molecular interactions.
Knock-in
Knock-in of epitope or fluorescent tags into IgA heavy chain or J chain allows tracking of dimeric IgA in live cells and tissues. This enables visualization of secretion and transcytosis.
Overexpression
Overexpression of MZB1 or pIgR can enhance dimeric IgA secretion and transport, providing gain-of-function models. These models are useful for testing therapeutic strategies to boost mucosal immunity.
How EDITGENE Supports dimeric IgA immunoglobulin complex Research
Researchers studying dimeric IgA immunoglobulin complex-related genes often need to determine whether a candidate gene is causally involved in assembly, secretion, or transport. EDITGENE provides a comprehensive suite of CRISPR services to enable such functional studies.
Contact EDITGENE today to design your custom CRISPR model for dimeric IgA immunoglobulin complex research.
Frequently Asked Questions About dimeric IgA immunoglobulin complex
What is GO:0071750?
GO:0071750 is the Gene Ontology term for the dimeric IgA immunoglobulin complex, a secreted antibody complex of two IgA monomers linked by disulfide bonds and a J chain.
What genes are involved in dimeric IgA immunoglobulin complex?
Key genes include IGHA1, IGHA2, IGKC, IGLC1, JCHAIN, PIGR, and MZB1.
Where is dimeric IgA found?
Dimeric IgA is present in the extracellular space, mucosal areas, other tissues, and circulating in blood or lymph.
What is the role of J chain in dimeric IgA?
The J chain bridges two IgA monomers via disulfide bonds and is required for efficient secretion of dimeric IgA.
How is dimeric IgA transported across epithelia?
The polymeric immunoglobulin receptor (pIgR) binds dimeric IgA and transports it across epithelial cells in a process called transcytosis.
What diseases are associated with dimeric IgA?
Selective IgA deficiency, cystic fibrosis lung disease, and gut inflammation are associated with defects in dimeric IgA production or function.
What is the difference between dimeric IgA and secretory IgA?
Secretory IgA is dimeric IgA complexed with the secretory component, a fragment of pIgR, found in mucosal secretions.
How can I study dimeric IgA in the lab?
Common methods include non-reducing SDS-PAGE, co-immunoprecipitation, transcytosis assays, and CRISPR knockout models.
What is the role of MZB1 in dimeric IgA?
MZB1 promotes the secretion of J-chain-containing dimeric IgA and is critical for suppression of gut inflammation.
Can CRISPR be used to study dimeric IgA?
Yes, CRISPR knockout, knock-in, and overexpression models are powerful tools to dissect the function of genes involved in dimeric IgA assembly and transport.
Conclusion
The dimeric IgA immunoglobulin complex (GO:0071750) is a key mediator of mucosal immunity, with essential roles in immune exclusion and host defense. Its assembly requires J chain and its transport depends on pIgR, and defects in these processes are linked to human diseases such as selective IgA deficiency and cystic fibrosis. Continued research using CRISPR models and biochemical assays will further illuminate its regulation and therapeutic potential.
References
- 1. Collin AM et al.. 2020. Lung immunoglobulin A immunity dysregulation in cystic fibrosis.. EBioMedicine 60:102974 PMID: 32927272
- 2. Yel L. 2010. Selective IgA deficiency.. J Clin Immunol 30(1):10-6 PMID: 20101521
- 3. Diebel LN et al.. 2011. Disparate effects of bacteria and Toll-like receptor-dependant bacterial ligand stimulation on immunoglobulin A transcytosis.. J Trauma 70(3):691-700 PMID: 21610360
- 4. Asano M et al.. 2011. Polymeric immunoglobulin receptor.. J Oral Sci 53(2):147-56 PMID: 21712618
- 5. Chintalacharuvu KR et al.. 1994. Disulfide bond formation between dimeric immunoglobulin A and the polymeric immunoglobulin receptor during hepatic transcytosis.. Hepatology 19(1):162-73 PMID: 8276353
- 6. Xiong E et al.. 2019. MZB1 promotes the secretion of J-chain-containing dimeric IgA and is critical for the suppression of gut inflammation.. Proc Natl Acad Sci U S A 116(27):13480-13489 PMID: 31127044
- 7. Deitcher DL et al.. 1986. Functional expression of the polymeric immunoglobulin receptor from cloned cDNA in fibroblasts.. J Cell Biol 102(3):911-9 PMID: 3753981
- 8. Kawanishi H et al.. 1989. Aging-associated intrinsic defects in IgA production by murine Peyer's patch B cells stimulated by autoreactive Peyer's patch T cell hybridoma-derived B cell stimulatory factors (BSF).. Mech Ageing Dev 49(1):61-78 PMID: 2787459
