NR4A1 Antibody

What is NR4A1 and what are its alternative names in the scientific literature?

NR4A1 (Nuclear Receptor Subfamily 4 Group A Member 1) is a member of the steroid-thyroid hormone-retinoid receptor superfamily. In the scientific literature, it is also referred to as Nur77, TR3, NGFI-B, hmr, n10, GFRP1, NAK-1, ST-59, hormone receptor, nerve growth factor IB, nuclear protein N10, and testicular receptor 3. This nuclear receptor functions as a transcription factor involved in various cellular processes including cell growth, apoptosis, and inflammation . When designing experiments or conducting literature searches, researchers should include these alternative names to ensure comprehensive results.

What applications have NR4A1 antibodies been validated for in scientific research?

NR4A1 antibodies have been validated for multiple applications, with varying degrees of effectiveness depending on the specific antibody clone and manufacturer. The most commonly validated applications include:

Researchers should review validation data from manufacturers and published literature before selecting an antibody for their specific application .

How should I optimize sample preparation for maximum NR4A1 detection?

Optimal sample preparation for NR4A1 detection depends on the application:

For Western blot applications:

• Use RIPA or NP-40 lysis buffers containing protease inhibitors

• Include phosphatase inhibitors if studying phosphorylated NR4A1

• Avoid repeated freeze-thaw cycles of the sample

• Consider nuclear extraction protocols since NR4A1 is predominantly nuclear under basal conditions

For IHC applications:

• Use freshly fixed tissues (10% neutral buffered formalin is recommended)

• Perform antigen retrieval with TE buffer at pH 9.0 for optimal results

• Alternatively, citrate buffer at pH 6.0 can be used for antigen retrieval

For challenging samples, consider enrichment strategies such as subcellular fractionation to increase detection sensitivity.

What positive controls are recommended for validating NR4A1 antibodies?

Based on the literature, the following positive controls are recommended for NR4A1 antibody validation:

Additionally, B16F10 melanoma cells have shown significant NR4A1 expression in recent cancer studies . For researchers investigating stress responses, serum-starved followed by serum-replenished MCF10A and M231 breast epithelial cells demonstrate dynamic NR4A1 expression patterns .

How can I distinguish between NR4A1 and other NR4A family members (NR4A2, NR4A3)?

Distinguishing between NR4A family members requires careful antibody selection and experimental controls:

• Select antibodies raised against non-conserved regions of NR4A1 to minimize cross-reactivity

• Validate specificity using:

  • NR4A1 knockout/knockdown cells as negative controls

  • Western blots to confirm the correct molecular weight (NR4A1: 64-68 kDa)

  • Competitive blocking experiments with recombinant proteins

Research has shown that well-characterized NR4A1-targeting PROTACs like NR-V04 selectively reduce NR4A1 protein levels while sparing NR4A2 and NR4A3 . This differential response can be used to validate antibody specificity. Additionally, expression patterns differ between family members - NR4A2 displays more ubiquitous presence across immune cell populations, while NR4A3 predominantly appears in monocytes, macrophages, and dendritic cells .

What could cause variability in NR4A1 detection across different experimental conditions?

Several factors can contribute to variability in NR4A1 detection:

• Dynamic expression patterns: NR4A1 is an immediate early gene whose expression can change rapidly in response to stimuli. Time course studies have shown that NR4A1 levels peak at different times following stimulation compared to other early response genes like FOS and EGR1 .

• Post-translational modifications: NR4A1 undergoes various modifications including phosphorylation and acetylation that can affect antibody recognition.

• Subcellular localization shifts: NR4A1 can translocate between the nucleus and mitochondria, which can affect detection depending on sample preparation methods .

• Chromatin association: NR4A1 dynamically interacts with RNA polymerase and chromatin in stress conditions, which can mask epitopes and reduce antibody accessibility .

• Epigenetic regulation: Long-term stimulation with inflammatory factors like IL-1β can lead to histone deacetylation and diminished NR4A1 expression .

Understanding these factors is essential for experimental design and accurate interpretation of results.

How can I troubleshoot non-specific binding or high background issues when using NR4A1 antibodies?

When experiencing high background or non-specific binding with NR4A1 antibodies, consider these approaches:

• Optimize blocking conditions: Use 5% BSA instead of milk for Western blots as milk may contain factors that cross-react with nuclear receptor antibodies.

• Adjust antibody concentration: Titrate the antibody to determine optimal concentration. For Western blot applications, dilutions between 1:500-1:2000 are typically recommended .

• Increase washing stringency: Add 0.1-0.3% Tween-20 to wash buffers and increase washing duration.

• Preadsorb antibody: Pre-incubate the antibody with non-target tissues or cell lysates to remove cross-reactive antibodies.

• Use validation controls: Include NR4A1 knockdown/knockout samples as negative controls to identify non-specific bands or staining.

• Consider fixation methods: For IF/IHC, different fixation protocols can affect epitope accessibility. Test multiple fixation methods.

• Account for endogenous peroxidase activity: For IHC, use appropriate quenching steps to minimize background from endogenous peroxidase activity.

How can NR4A1 antibodies be utilized to study the protein's role in tumor microenvironment and cancer progression?

NR4A1 antibodies are valuable tools for investigating this protein's complex role in cancer:

• Expression profiling: IHC and IF with NR4A1 antibodies can map expression patterns within heterogeneous tumor tissue. Studies have shown that NR4A1 is differentially expressed between central and peripheral areas of osteoarthritic cartilage and may follow similar patterns in tumors .

• Correlation with clinical outcomes: NR4A1 staining intensity can be quantified and correlated with patient survival data to establish prognostic value. TCGA datasets have revealed negative correlations between NR4A1 expression and anti-tumor immune responses in melanoma patients .

• Immune cell infiltration studies: Multiplex IF using NR4A1 antibodies together with immune cell markers can characterize tumor-infiltrating populations. Research has demonstrated that NR4A1 expression is particularly evident in tumor-infiltrating B cells, monocytes, macrophages, dendritic cells, regulatory T cells, and exhausted CD8+ T cells .

• Response to therapeutics: Western blotting with NR4A1 antibodies can assess how treatment affects NR4A1 expression and degradation. The PROTAC NR-V04 effectively degrades NR4A1 within hours of treatment in vitro and sustains degradation for at least 4 days in vivo .

• ChIP-seq applications: NR4A1 antibodies can be used to identify genome-wide binding patterns of NR4A1 in different cancer types. This approach has revealed that NR4A1 predominantly binds to gene bodies rather than transcription start sites .

What approaches exist for studying NR4A1's role in regulating oxidative stress and endoplasmic reticulum stress?

NR4A1 plays a critical role in modulating cellular stress responses. To investigate this function:

• Protein-protein interaction studies: Co-immunoprecipitation with NR4A1 antibodies can identify interaction partners in stress response pathways. Research has shown that NR4A1 interacts with RNA Polymerase II under basal conditions, but this interaction is disrupted during cellular stress .

• Stress marker correlation: Dual labeling with NR4A1 antibodies and stress markers (GRP78, CHOP, ATF-4) can reveal relationships between NR4A1 expression and stress responses. Proteomic analysis following NR4A1 knockdown has identified induction of these endoplasmic reticulum stress markers .

• Genetic manipulation combined with protein detection: RNAi-mediated knockdown of NR4A1 followed by Western blot analysis with antibodies against stress markers provides mechanistic insights. In pancreatic cancer cells, NR4A1 knockdown increased reactive oxygen species (ROS) and induced expression of endoplasmic reticulum stress markers .

• Target gene expression analysis: ChIP with NR4A1 antibodies followed by qPCR of stress-related genes can identify direct regulatory targets. NR4A1 has been shown to regulate thioredoxin domain containing 5 (TXNDC5), which is critical for ROS metabolism .

• Pharmacological approaches: Treatment with NR4A1 antagonists (like DIM-C-pPhOH) or degraders (like NR-V04) followed by Western blot analysis can reveal therapeutic potential. These compounds have been shown to induce cancer cell death through activation of ROS/endoplasmic reticulum stress pathways .

How is NR4A1 being investigated in inflammatory and autoimmune contexts?

Recent research has highlighted NR4A1's role in inflammation regulation, particularly in:

• Chondrocyte inflammation: Studies using NR4A1 antibodies have demonstrated that overexpression of NR4A1 can effectively inhibit IL-1β-induced upregulation of inflammatory mediators (COX-2, MMP3, MMP9, MMP13) in chondrocytes, suggesting a protective role in osteoarthritis .

• NF-κB pathway regulation: Western blot analysis using NR4A1 antibodies has shown that NR4A1 acts as a natural negative feedback regulator of the NF-κB signaling pathway. The relative luciferase activity driven by NF-κB response elements was significantly lower in NR4A1 overexpression experiments .

• Immune cell subpopulations: Flow cytometry incorporating NR4A1 antibodies has revealed differential expression patterns across immune cell types. NR4A1 expression has been particularly noted in B cells, monocytes/macrophages, dendritic cells, regulatory T cells, and exhausted CD8+ T cells within the tumor microenvironment .

• Chronic inflammation models: Immunohistochemistry with NR4A1 antibodies in human osteoarthritis samples has shown that NR4A1 positive rates increase initially but decrease in chronically inflamed areas, suggesting a failure of this protective mechanism over time .

• Temporal dynamics of expression: Time course studies have demonstrated that chronic inflammatory stimulation results in the rapid decline of NR4A1 after an initial peak, which correlates with changes in histone acetylation levels at H4 lys8 and H3 lys27 .

What is known about NR4A1's role in platelets and cardiovascular function?

An emerging area of research is NR4A1's function in platelets and cardiovascular health:

Recent studies have demonstrated that NR4A1 is expressed in both human and mouse platelets, acting as a negative regulator of platelet activation. Platelet-specific NR4A1 deletion accelerates arterial occlusive thrombus formation and enhances collagen/epinephrine-induced pulmonary thromboembolism in mouse models .

Research investigating the underlying mechanisms has identified CAP1 (adenylyl cyclase-associated protein 1) as a direct downstream interacting protein of NR4A1 in platelets. NR4A1 deletion decreased cAMP levels and phosphorylation of VASP (vasodilator-stimulated phosphoprotein), while NR4A1-specific agonists increased these parameters .

Interestingly, NR4A1 expression in platelets is upregulated in conditions of hypercholesterolemia, apparently derived from its upregulation in megakaryocytes. This suggests a potential compensatory mechanism to counteract platelet hyperreactivity in cardiovascular disease states .

To investigate these phenomena, researchers can employ:

• Western blotting with NR4A1 antibodies to detect expression in platelet lysates

• Immunofluorescence to visualize NR4A1 localization in platelets

• Co-immunoprecipitation to study interactions with CAP1 and other signaling proteins

• Flow cytometry to assess platelet activation markers in relation to NR4A1 expression

How are novel therapeutic approaches targeting NR4A1 being developed and assessed?

Innovative therapeutic strategies targeting NR4A1 are being actively developed:

• PROTAC technology: The first-of-its-kind proteolysis-targeting chimera (PROTAC) against NR4A1, named NR-V04, efficiently degrades NR4A1 within hours of treatment in vitro and maintains degradation for at least 4 days in vivo. This approach has shown robust tumor inhibition and sometimes complete eradication of established melanoma tumors in preclinical models .

• Target validation approaches: NR4A1 antibodies are essential for confirming target engagement and measuring degradation efficiency of these novel therapeutics. Western blotting has demonstrated that NR-V04 selectively reduces NR4A1 protein levels while sparing related family members NR4A2 and NR4A3 .

• Mechanistic investigations: Studies using NR4A1 antibodies have uncovered unexpected mechanisms of action for these therapeutics, including significant induction of tumor-infiltrating B cells and inhibition of monocytic myeloid-derived suppressor cells (m-MDSCs), two clinically relevant immune cell populations in human melanomas .

• Small molecule antagonists: Compounds like DIM-C-pPhOH that antagonize NR4A1 activity have been evaluated using Western blotting to confirm their effects on downstream stress pathways. These agents have been shown to induce ROS and endoplasmic reticulum stress, leading to cancer cell death .

• Pharmacodynamic monitoring: NR4A1 antibodies enable researchers to track the durability and specificity of target engagement in preclinical models, which is crucial for predicting clinical efficacy and optimizing dosing schedules for first-in-human studies .

Through these approaches, NR4A1-targeted therapeutics hold promise for enhancing anti-cancer immune responses and offering new treatment options for various cancer types.