IARS1 Antibody

What is IARS1 and what is its primary function in cellular processes?

IARS1 (isoleucyl-tRNA synthetase 1) is a member of the Class-I aminoacyl-tRNA synthetase protein family that catalyzes the specific attachment of isoleucine to its cognate tRNA in a two-step reaction: first, isoleucine is activated by ATP to form isoleucine-AMP, and then it's transferred to the acceptor end of the tRNA . In humans, the canonical IARS1 protein consists of 1262 amino acid residues with a molecular mass of approximately 144.5 kDa . It primarily localizes to the cytoplasm and is predominantly expressed in liver and muscle tissues . This enzyme plays a crucial role in protein synthesis by ensuring the accurate incorporation of isoleucine during translation.

How should researchers select the appropriate IARS1 antibody for their specific experimental needs?

When selecting an IARS1 antibody, researchers should consider the following methodological approach:

• Define your experimental application: Different antibodies perform optimally in specific applications. For instance, ab229643 has been validated for immunoprecipitation (IP), Western blot (WB), and immunohistochemistry on paraffin-embedded tissues (IHC-P) , while ab31533 is suitable for WB and immunocytochemistry/immunofluorescence (ICC/IF) .

• Consider species reactivity: Verify whether the antibody cross-reacts with your species of interest. Some IARS1 antibodies react only with human samples, while others (like ab229643) recognize both human and rat IARS1 .

• Validate antibody specificity: Review Western blot data provided by manufacturers showing detection of IARS1 in different cell lines. For example, ab229643 has been tested on HEK-293T, A431, HeLa, and HepG2 cell extracts .

• Check antibody format: Determine whether you need a conjugated or unconjugated antibody based on your detection system.

• Review published literature: Examine publications that have successfully used specific IARS1 antibodies in applications similar to yours.

What are the optimal conditions for Western blot detection of IARS1?

For optimal Western blot detection of IARS1, researchers should follow these methodological guidelines:

• Sample preparation: Prepare whole cell extracts (30 μg recommended) from relevant cell lines such as HEK-293T, A431, HeLa, or HepG2 cells, which have been shown to express detectable levels of IARS1 .

• Gel selection: Use a 5% SDS-PAGE gel to effectively separate this large protein (144.5 kDa) .

• Antibody dilution: For ab229643, a 1:4000 dilution has been validated to produce specific signals .

• Blocking conditions: Use standard blocking buffers containing 5% non-fat dry milk or BSA in TBS-T.

• Detection system: Select a detection system compatible with your secondary antibody (HRP-conjugated or fluorescent).

• Controls: Include positive controls (liver or muscle tissue extracts) and negative controls to validate specificity.

How are IARS1 mutations linked to human disease pathogenesis?

IARS1 mutations have been implicated in several distinct pathologies:

• Growth and developmental disorders: Mutations in the IARS1 gene are associated with growth retardation, impaired intellectual development, hypotonia, and hepatopathy .

• Pulmonary alveolar proteinosis (PAP): A case study of a 5-month-old boy with IARS1 deficiency revealed PAP as the initial and predominant manifestation . This rare lung disease is characterized by accumulation of surfactant proteins and lipids in the alveoli.

• Mitochondrial diseases: Studies of IARS1-deficient mice demonstrated that mutations (such as V79L) can lead to mitochondrial dysfunction, resulting in hepatic triglyceride accumulation and elevated serum ornithine carbamoyltransferase levels, indicative of mitochondrial hepatopathy .

• Inflammatory bowel disease (IBD): A homozygous c.290A>G, p.(Asp97Gly) variant in cytosolic IARS1 was identified in a case of refractory very early-onset IBD, suggesting recessive mutations in cytosolic isoleucyl-tRNA synthetase can cause IBD .

• Weak calf syndrome: In cattle, the homozygous V79L mutation leads to weak calf syndrome and reduces enzyme activity by approximately 40% .

What cellular mechanisms are disrupted in IARS1-deficient conditions?

IARS1 deficiency disrupts multiple cellular mechanisms:

• Mitochondrial dysfunction: Research using IARS1 siRNA knockdown in HepG2 cells demonstrated decreased mitochondrial membrane potential and increased reactive oxygen species (ROS) production . The JC-1 assay showed a shift from red-dotted staining (intact membrane potential) to increased green fluorescence (lost membrane potential) in IARS1-knockdown cells .

• Protein synthesis disruption: Decreased isoleucyl-tRNA levels lead to global reduction in protein synthesis, particularly affecting mitochondrial proteins .

• Altered protein expression profiles: Proteomic analysis of IARS1 V79L mutant mice revealed 108 significantly altered proteins (42 upregulated, 66 downregulated) compared to wild-type mice .

• Increased oxidative stress: The mitochondrial dysfunction observed in IARS1-deficient cells leads to increased ROS production, potentially causing DNA damage .

• Immune system dysregulation: In clinical cases, immune phenotyping revealed reduced mucosal-associated invariant T-cells and natural killer cell frequencies (<0.2% and 1% of lymphocytes, respectively, compared to the normal range of 1-15%) .

How can IARS1 antibodies be utilized to study disease mechanisms?

IARS1 antibodies serve as valuable tools for investigating disease mechanisms through several methodological approaches:

• Protein expression analysis: Western blotting with IARS1 antibodies can quantify expression levels in patient-derived cells or tissues compared to healthy controls .

• Subcellular localization studies: Immunofluorescence using IARS1 antibodies can determine whether mutations affect the normal cytoplasmic localization of IARS1 .

• Protein-protein interaction studies: Immunoprecipitation with IARS1 antibodies can identify novel interaction partners that may be disrupted in disease states .

• Tissue distribution analysis: Immunohistochemistry can map IARS1 expression patterns in affected tissues, such as liver, muscle, intestinal mucosa, or lung tissue in PAP patients .

• Mouse model validation: IARS1 antibodies can confirm the molecular phenotype of genetically engineered mouse models, such as the IARS1 V79L mutant mice .

What are the key considerations for optimizing immunohistochemistry protocols using IARS1 antibodies?

For optimal immunohistochemistry results with IARS1 antibodies, researchers should consider:

• Tissue fixation and processing: Use 10% neutral-buffered formalin fixation followed by paraffin embedding. Overfixation can mask epitopes and reduce antibody binding.

• Antigen retrieval: Heat-induced epitope retrieval (HIER) using citrate buffer (pH 6.0) or EDTA buffer (pH 9.0) is typically effective for IARS1 detection.

• Antibody selection: Choose antibodies specifically validated for IHC-P applications, such as ab229643 .

• Signal amplification: For tissues with low IARS1 expression, consider using tyramide signal amplification or polymer-based detection systems.

• Positive controls: Include liver or muscle tissue sections, which express high levels of IARS1 .

• Negative controls: Include sections incubated with isotype control antibodies or secondary antibody alone.

• Counterstaining: Use hematoxylin for nuclear visualization without obscuring cytoplasmic IARS1 staining.

What approaches can be used to validate IARS1 antibody specificity?

Rigorous validation of IARS1 antibody specificity is crucial and should include:

• Western blot analysis: Confirm antibody detects a single band of expected molecular weight (144.5 kDa) in relevant cell lines (HEK-293T, A431, HeLa, HepG2) .

• Peptide competition assay: Pre-incubation of the antibody with the immunizing peptide should abolish the signal.

• Knockdown/knockout controls: Compare staining in IARS1 siRNA-treated cells versus negative control siRNA-treated cells .

• Multiple antibody approach: Use two different antibodies targeting distinct epitopes of IARS1 to confirm specificity.

• Mass spectrometry validation: Perform immunoprecipitation followed by mass spectrometry to confirm the identity of the pulled-down protein.

• Cross-reactivity testing: If working with non-human samples, test antibody reactivity against recombinant IARS1 proteins from relevant species.

How can researchers effectively use IARS1 antibodies in co-immunoprecipitation experiments?

For successful co-immunoprecipitation (co-IP) experiments using IARS1 antibodies:

• Cell lysis optimization: Use gentle lysis buffers (e.g., 25 mM Tris-HCl pH 7.4, 150 mM NaCl, 1 mM EDTA, 1% NP-40, 5% glycerol) with protease inhibitors to preserve protein-protein interactions.

• Antibody selection: Choose antibodies specifically validated for immunoprecipitation, such as ab229643 .

• Pre-clearing: Pre-clear lysates with protein A/G beads to reduce non-specific binding.

• Antibody binding: Incubate pre-cleared lysates with IARS1 antibody (2-5 μg per 1 mg of protein) overnight at 4°C.

• Bead selection: Use protein A beads for rabbit polyclonal antibodies like ab229643 and ab31533 .

• Washing stringency: Adjust washing buffer stringency to minimize background while preserving specific interactions.

• Elution conditions: Use gentle elution methods (such as competitive elution with immunizing peptide) to maintain the integrity of co-precipitating proteins.

• Controls: Include IgG isotype control and input samples to distinguish specific interactions from background.

How can IARS1 mouse models be effectively used to study human IARS1-related disorders?

IARS1 mouse models provide valuable insights into human disease mechanisms, as demonstrated by the following methodological approach:

• Genetic engineering strategy: Use CRISPR/Cas9 to introduce specific mutations found in human patients, such as the V79L mutation that leads to a hypomorphic IARS1 variant with approximately 40% reduced enzyme activity .

• Phenotypic characterization: Assess mice for disease-relevant parameters including:

  • Hepatic triglyceride levels (significantly increased in IARS1 V79L mice)

  • Serum ornithine carbamoyltransferase levels (elevated in IARS1 V79L mice)

  • Growth parameters and development

  • Lung pathology (for PAP-related phenotypes)

  • Intestinal pathology (for IBD-related phenotypes)

• Molecular analysis: Use IARS1 antibodies for protein expression analysis in affected tissues, combined with RNA sequencing and proteomic approaches to identify dysregulated pathways .

• Therapeutic testing: Evaluate potential treatments such as amino acid supplementation (e.g., L-isoleucine at 35-70 mg/kg/day), which improved outcomes in human patients with IARS1 deficiency .

• Comparative analysis: Compare mouse phenotypes with human patient data to validate the model and identify conserved disease mechanisms.

What are the methodological approaches for studying IARS1's role in mitochondrial function?

To investigate IARS1's impact on mitochondrial function:

• Mitochondrial membrane potential assessment: Use JC-1 dye, which exhibits red fluorescence in mitochondria with intact membrane potential and green fluorescence when membrane potential is disrupted. IARS1-knockdown cells show decreased red fluorescence and increased green fluorescence .

• ROS detection: Employ mtSOX Deep Red probe to detect mitochondrial superoxide radicals, which are elevated in IARS1-deficient cells .

• Cellular knockdown models: Create IARS1-deficient cell models using siRNA transfection in hepatocyte cell lines (e.g., HepG2), confirming knockdown efficiency by Western blot (40-60% reduction in IARS1 expression is typically achieved) .

• Proteomic analysis: Perform comparative proteomics of wild-type versus IARS1-mutant tissues to identify mitochondrial proteins affected by IARS1 deficiency. This revealed decreased levels of mitochondrial function-associated proteins like NME4 (mitochondrial nucleoside diphosphate kinase) in IARS1 V79L mice .

• Mitochondrial morphology assessment: Use electron microscopy or MitoTracker staining combined with confocal microscopy to evaluate structural changes in mitochondria.

How can researchers investigate the non-canonical functions of IARS1 beyond tRNA aminoacylation?

To explore IARS1's non-canonical functions:

• Protein interaction network analysis: Use immunoprecipitation with IARS1 antibodies followed by mass spectrometry to identify novel interaction partners beyond the translation machinery .

• Differential proteomics: Compare proteomes of wild-type and IARS1-mutant tissues to identify proteins affected by IARS1 dysfunction. In IARS1 V79L mice, 108 proteins showed significant changes in expression (42 upregulated, 66 downregulated) .

• Phosphoproteomics: Analyze phosphorylation changes in IARS1-deficient models, as IARS1 mutations were found to upregulate substrates of kinases associated with DNA repair mechanisms (CDK1, ATM, PRKDC) .

• Domain-specific mutations: Create constructs with mutations in specific IARS1 domains to dissect which regions are responsible for canonical versus non-canonical functions.

• Subcellular fractionation: Determine if IARS1 localizes to cellular compartments beyond the cytoplasm under specific conditions, potentially indicating non-canonical functions.

What are common technical challenges when using IARS1 antibodies and how can they be addressed?

Researchers may encounter several technical challenges when working with IARS1 antibodies:

• High molecular weight detection issues: Due to IARS1's large size (144.5 kDa), researchers should:

  • Use low percentage gels (5-8% SDS-PAGE)

  • Extend transfer time during Western blotting

  • Consider specialized transfer buffers for high molecular weight proteins

• Non-specific binding: To reduce background:

  • Optimize antibody dilution (start with manufacturer's recommendation, e.g., 1:4000 for ab229643)

  • Increase washing steps (4-5 washes, 5-10 minutes each)

  • Test different blocking agents (5% milk, 5% BSA, or commercial blocking buffers)

• Weak signal in immunostaining: To enhance detection:

  • Optimize antigen retrieval methods for tissue sections

  • Increase antibody concentration or incubation time

  • Consider signal amplification systems (tyramide amplification, polymer detection)

• Degradation during sample preparation: To maintain protein integrity:

  • Use fresh samples or proper storage (-80°C)

  • Include protease inhibitor cocktails in lysis buffers

  • Maintain samples at 4°C during processing

• Cross-reactivity with other AARSs: To ensure specificity:

  • Validate with knockdown controls

  • Use antibodies generated against unique regions of IARS1

How should researchers interpret IARS1 expression data in the context of disease models?

When interpreting IARS1 expression data in disease models:

• Expression level changes: Consider that altered IARS1 expression may reflect compensatory mechanisms rather than primary pathology. In some mitochondrial diseases, upregulation of certain AARSs occurs as a compensatory response.

• Tissue-specific effects: Evaluate IARS1 expression in relevant tissues (liver, muscle) where it's normally highly expressed . Different tissues may show variable sensitivity to IARS1 dysfunction.

• Functional correlation: Correlate IARS1 expression levels with functional outcomes:

  • Mitochondrial membrane potential

  • ROS production

  • Global protein synthesis rates

  • Specific clinical parameters (growth, liver function, etc.)

• Mutation-specific effects: Different IARS1 mutations may affect expression or function differently. The V79L mutation reduces enzyme activity by 40% without necessarily altering expression levels .

• Data integration: Integrate IARS1 expression data with proteomic profiles to identify downstream effectors. In IARS1 V79L mice, 108 proteins showed altered expression .

• Therapeutic response markers: Monitor IARS1 expression and downstream effects during therapeutic interventions, such as isoleucine supplementation in IARS1-deficient patients .