IFNA14 Human

What is IFNA14 and how is it classified in the interferon family?

IFNA14, also known as interferon alpha-14, interferon alpha-H, or LeIF H, is a protein encoded by the IFNA14 gene in humans . It belongs to the alpha/beta interferon family and is specifically categorized as a type I interferon . IFNA14 shares over 95% amino acid sequence homology with other interferon-alpha proteins, highlighting the high degree of conservation within this interferon subgroup . Type I interferons share a common cell surface receptor composed of two subunits: a 100 kDa ligand-binding subunit (IFN-alpha R2) and a 125 kDa ligand binding and signal transduction subunit (IFN-alpha R1) .

What are the primary biological functions of IFNA14?

IFNA14, like other type I interferons, exhibits both antiviral and immunomodulatory activities on target cells . It is primarily produced by macrophages and stimulates the production of two key enzymes: a protein kinase and an oligoadenylate synthetase . These enzymes are crucial components of the cellular antiviral response mechanism. The protein kinase phosphorylates and inactivates eukaryotic initiation factor 2 (eIF-2), which leads to inhibition of viral protein synthesis, while oligoadenylate synthetase activates RNase L, which degrades viral RNA . Through these and other mechanisms, IFNA14 contributes to the body's defense against viral infections and may also play roles in regulating inflammation and immune cell functions.

How did IFNA14 evolve in primates and what does this suggest about its function?

IFNA14 belongs to the evolutionarily conserved cluster of IFNα subtypes that emerged during primate evolution . The IFNA gene first appeared approximately 95-105 million years ago and underwent duplication and conversion events that gave rise to expanded sets of IFNα subtypes in placental mammals . IFNA14 specifically arose after old world monkeys (OWM) and before the divergence of orangutans and other great apes, making it part of the conserved set of IFNA subtypes in higher primates .

Evolutionary analysis shows that IFNA14 has undergone selection against nonsynonymous variants, suggesting functional constraints and biological importance . This conservation implies that IFNA14 likely evolved to counter pathogens common to the most recent common ancestor of OWM and great apes, highlighting its critical role in primate immunity against specific evolutionary threats.

What genomic and polymorphism patterns are observed in IFNA14?

Analysis of human polymorphisms across sub-Saharan African, Asian, and European populations has revealed that IFNA14 is among the IFNα subtypes with the fewest polymorphisms, alongside IFNA6, IFNA8, and IFNA13 . This limited genetic variation indicates strong purifying selection, suggesting critical functional importance that constrains evolutionary changes.

Interestingly, IFNA14 may have served as a genetic template for the creation of other IFNα subtypes through partial conversion events. Evidence suggests that IFNA4, IFNA10, and IFNA17 could be products of partial conversions from IFNA14 or IFNA21 . These relationships illustrate the complex evolutionary history of IFNα subtypes and highlight IFNA14's potential role as a genetic precursor for variant subtypes that emerged later in primate evolution.

How is IFNA14 expression regulated at the transcriptional level?

IFNA14 expression is primarily controlled by interferon regulatory factors (IRFs), with IRF3 and IRF7 playing dominant roles . The IFNA14 promoter region shares structures similar to other conserved IFNα subtypes, containing three IRF regulatory modules that determine sensitivity to IRF3 and IRF7 .

As part of the conserved IFNα subtype cluster, IFNA14 expression is induced by activated IRF3 alone, which distinguishes it from variant subtypes that require IRF7 activation . This differential regulation mechanism explains why IFNA14 is often co-expressed with IFNβ and other conserved IFNα subtypes in early immune responses. The promoter structure of IFNA14 resembles that of IFNA2, which is representative of the conserved subtype promoters (except IFNA21) and differs from the variant subtypes in terms of IRF sensitivity patterns .

What expression patterns does IFNA14 show in different cell types and in response to various stimuli?

IFNA14, as a conserved IFNα subtype, shows distinct expression patterns in different cellular contexts:

• In cells that do not constitutively express IRF7, such as most non-immune cells, stimulation with viral RNA or synthetic analogs like poly I:C primarily induces expression of IFNA14 along with other conserved subtypes .

• In plasmacytoid dendritic cells (pDCs), which constitutively express IRF7, potent stimulation leads to expression of all IFNα subtypes including IFNA14, while weaker stimulation with specific ligands like CpG B class oligodeoxynucleotides induces a more limited set of subtypes .

• In experimental models using the U937 histiocytic cell line infected with Sendai virus, infection at high multiplicity of infection (MOI) leads to expression almost exclusively of conserved subtypes including IFNA14, while infection at low MOI induces expression of all subtypes .

This differential expression pattern suggests that IFNA14 is part of the early interferon response, often induced before variant subtypes in the context of the IFNβ-IRF7 forward feedback loop .

What recombinant IFNA14 protein options are available for research, and how do they differ?

Multiple recombinant IFNA14 protein options are available for research purposes, differing in expression systems, tags, and applications:

E. coli-derived IFNA14 is typically supplied in phosphate-buffered saline containing 0.1% bovine serum albumin, should be stored at -20 to -70°C, and users should avoid repeated freeze-thaw cycles to maintain protein integrity . Researchers should select the appropriate recombinant protein based on their specific experimental requirements, considering factors such as post-translational modifications, tag presence, and functional needs.

How can IFNA14 biological activity be measured in laboratory settings?

IFNA14 biological activity can be measured using several established assays:

• Cytopathic Effect Inhibition Assay: This is a standard method for determining interferon activity. Two common implementations include:

  • Bovine (MDBK/VSV) assay - performed as described by Rubinstein et al., with an EC₅₀ for interferon of approximately 5 U/ml .

  • Human (A549/EMCV) assay - performed as described by Budd et al., with an EC₅₀ for interferon of approximately 1 U/ml .

• Antiviral Response Measurement: Quantification of interferon-stimulated genes (ISGs) using qRT-PCR following IFNA14 treatment of target cells .

• Protein Phosphorylation Analysis: Western blotting to detect phosphorylation of STAT1/STAT2 following IFNA14 treatment of cells expressing IFNAR1/IFNAR2 .

• Reporter Cell Lines: Using cells transfected with interferon-sensitive response elements (ISRE) linked to reporter genes like luciferase to quantify IFNA14 activity.

When conducting these assays, it's important to include appropriate controls, such as other interferon subtypes, to enable comparative analysis of biological potency and specificity.

What antibodies and immunoassays are available for IFNA14 detection and quantification?

Several antibodies and immunoassays are available for IFNA14 detection and quantification:

When selecting antibodies for IFNA14 detection, researchers should consider:

• Potential cross-reactivity with other interferon alpha subtypes due to high sequence homology

• Validation status for specific applications (WB, IHC, ELISA)

• Whether conjugated antibodies (biotin, HRP) might benefit particular experimental designs

For quantitative measurement of IFNA14 in biological samples, ELISA kits offer the advantage of standardized protocols and calibrated standards, enabling reliable concentration determination in complex matrices like serum or cell culture supernatants .

How does IFNA14 functionally differ from other interferon alpha subtypes?

While all type I interferons signal through the same receptor complex, subtle functional differences exist between IFNA14 and other subtypes that may be significant in specific research contexts:

• Evolutionary Conservation: IFNA14 belongs to the evolutionarily conserved cluster of IFNα subtypes, suggesting it addresses common pathogenic threats that have remained relevant throughout primate evolution . This conservation implies distinct and potentially non-redundant functions compared to variant subtypes.

• Expression Patterns: IFNA14 expression is more readily induced by IRF3 activation alone compared to variant subtypes, positioning it among the "early response" interferons . This temporal expression pattern may indicate a specialized role in initial antiviral defense mechanisms.

• Receptor Binding Dynamics: Although all IFNα subtypes bind to the same receptor, subtle differences in binding affinity, kinetics, and the resulting conformational changes may lead to different signaling outcomes. Researchers investigating subtype-specific functions should consider employing receptor binding assays and downstream signaling analyses to characterize these differences.

• Antiviral Specificity: Limited evidence suggests that different IFNα subtypes may exhibit variable efficacy against specific viruses. When investigating IFNA14's antiviral properties, comparative studies against multiple viruses and alongside other subtypes can reveal potential specialization in antiviral activity.

What challenges exist in specifically studying IFNA14 apart from other interferon subtypes?

Researchers face several methodological challenges when attempting to study IFNA14 specifically:

• Sequence Homology: The high sequence similarity (>95%) between IFNα subtypes makes developing truly subtype-specific antibodies and detection methods challenging . Researchers should validate reagent specificity using recombinant protein panels and consider complementary approaches like gene expression analysis.

• Overlapping Functions: The functional redundancy among IFNα subtypes complicates the interpretation of experimental results. Knockout or knockdown approaches targeting IFNA14 alone may show limited phenotypes due to compensation by other subtypes.

• Expression Level Variability: IFNA14 is expressed at different levels depending on cell type, stimulation conditions, and temporal dynamics of the immune response . Researchers must carefully select appropriate experimental systems and time points for analysis.

• Recombinant Protein Considerations: When using recombinant IFNA14, researchers should be aware that different expression systems (bacterial, yeast, mammalian) may yield proteins with different post-translational modifications that could affect biological activity . Consistent usage of the same recombinant protein source throughout a study is recommended.

• Evolutionary Differences: When using animal models, researchers should note that the IFNα subtype repertoire differs between species, complicating direct translation of findings . Human-specific aspects of IFNA14 function may require humanized models or human cell systems.

What emerging research directions involve IFNA14 in disease contexts?

Several promising research directions involving IFNA14 warrant exploration:

• Viral Pathogen Specificity: Investigating whether IFNA14 shows particular efficacy against specific viral families could reveal specialized evolutionary adaptations. Comparative studies examining IFNA14 versus other subtypes against diverse viral challenges could identify unique antiviral signatures.

• Autoimmune Disease Relevance: Given that type I interferons are implicated in autoimmune disorders like systemic lupus erythematosus (SLE), examining the specific contribution of IFNA14 to pathogenesis could reveal subtype-specific effects. Analysis of IFNA14 expression patterns or genetic variants in patient cohorts might identify disease-relevant associations.

• Cancer Immunotherapy Applications: Type I interferons have anti-tumor properties and potential applications in cancer immunotherapy. Studies exploring whether IFNA14 exhibits unique anti-tumor activities or synergizes with specific checkpoint inhibitors could open new therapeutic avenues.

• Structure-Function Relationships: Detailed structure-function studies comparing IFNA14 with other subtypes could identify regions responsible for specific activities. This could enable the design of novel interferon variants with enhanced therapeutic properties.

• Receptor Complex Interactions: Exploring how IFNA14 engages with and signals through the IFNAR1/IFNAR2 complex, particularly in comparison to other subtypes, could reveal mechanistic insights into interferon signaling specificity and potentially identify novel regulatory mechanisms or interaction partners.