nr6a1a Antibody

What is NR6A1 and what are its primary functions?

NR6A1 (Nuclear Receptor Subfamily 6, Group A, Member 1), also known as GCNF (germ cell nuclear factor), is a member of the nuclear receptor superfamily of ligand-activated transcription factors. It functions primarily as a transcriptional repressor by binding to DNA sequences consisting of directly repeated (DR0) consensus motifs PuGGTCA with zero spacing .

NR6A1 plays crucial roles in several biological processes:

• Regulation of stem cell differentiation through suppression of pluripotency genes like Nanog and Oct4

• Control of lipid metabolism through the mammalian target of rapamycin complex 1 (mTORC1) pathway in liver cells

• Master regulation of embryonic development processes including body elongation, segmentation, patterning, and lineage allocation

• Binding to promoters of various growth factors including teratocarcinoma-derived growth factor 1, bone morphogenetic protein-15, and growth differentiation factor-9

Complete knockout of NR6A1 is embryonic lethal due to cardiovascular defects and failure to establish proper chorioallantoic connections, underscoring its essential developmental role .

What isoforms of NR6A1 exist and how do they differ?

NR6A1 produces multiple transcripts with distinct structural and functional characteristics:

• The canonical human NR6A1 protein consists of 480 amino acid residues with a molecular mass of approximately 54.4 kDa

• Up to five different protein isoforms have been reported for NR6A1

• In mouse models, two largely overlapping NR6A1 sense transcripts have been identified that produce proteins with identical DNA-binding and ligand-binding domains

• Both isoforms share a common 3' untranslated region containing multiple microRNA binding sites

• Within intron 3 of the long isoform, multiple antisense transcripts exist, including a long non-coding RNA (Nr6a1os) and a polycistronic transcript encoding miR-181a2 and miR-181b-2 microRNAs

Additionally, the gene locus produces lnc-Nr6a1, a long non-coding RNA that generates two polyadenylated isoforms (lnc-Nr6a1-1 and lnc-Nr6a1-2) and a longer non-polyadenylated microprocessor-driven lnc-pri-miRNA containing clustered pre-miR-181a2 and pre-miR-181b2 hairpins .

What species reactivity is available for NR6A1 antibodies?

NR6A1 antibodies show extensive cross-reactivity across multiple species due to the high conservation of this protein. Based on BLAST analysis of immunogen peptides, the following species reactivity has been documented:

• 100% sequence identity: Human, Chimpanzee, Gorilla, Gibbon, Monkey, Marmoset, Mouse, Rat, Hamster, Elephant, Panda, Dog, Bat, Bovine, Horse, Rabbit, Pig, Turkey, Chicken, Platypus

• 94% sequence identity: Stickleback, Pufferfish, Zebrafish

• 89% sequence identity: Xenopus

This broad cross-reactivity makes NR6A1 antibodies valuable tools for comparative studies across different model organisms, particularly when investigating evolutionarily conserved functions of this nuclear receptor.

What are the key considerations when selecting an NR6A1 antibody?

When selecting an NR6A1 antibody for research applications, researchers should consider:

• Target epitope specificity: Determine whether the antibody targets the DNA-binding domain, ligand-binding domain, or other regions of NR6A1. For instance, antibodies targeting the ligand-binding domain may be useful for studying protein-protein interactions and regulatory mechanisms .

• Antibody type: Consider whether polyclonal or monoclonal antibodies better suit your experimental needs. Polyclonal antibodies may offer broader epitope recognition but potentially lower specificity, while monoclonal antibodies provide consistent results with higher specificity to a single epitope .

• Host species: Select an antibody raised in a species appropriate for your experimental system to avoid cross-reactivity issues in multiple labeling experiments.

• Validated applications: Ensure the antibody has been validated for your specific application (e.g., Western blot, immunohistochemistry, immunoprecipitation, ELISA) .

• Isoform recognition: Confirm whether the antibody can distinguish between different NR6A1 isoforms or recognizes common regions shared by multiple isoforms .

• Species reactivity: Verify that the antibody recognizes NR6A1 in your species of interest, considering the high conservation across species .

How can I validate NR6A1 antibody specificity?

Validating antibody specificity is crucial for ensuring reliable experimental results. For NR6A1 antibodies, consider these validation approaches:

• Knockout/knockdown controls: Compare antibody reactivity in wild-type samples versus NR6A1 knockout or knockdown samples. Complete loss or significant reduction of signal in knockdown samples supports antibody specificity .

• Peptide competition assay: Pre-incubate the antibody with the immunizing peptide before application to your sample. Specific binding should be blocked by the peptide, resulting in signal reduction.

• Western blot analysis: Verify that the antibody detects bands of the expected molecular weight (approximately 54.4 kDa for the canonical form, with possible variations for other isoforms) .

• Multiple antibody comparison: Use different antibodies targeting distinct epitopes of NR6A1 and compare their staining patterns. Convergent results increase confidence in specificity.

• Heterologous expression: Test antibody reactivity against recombinant NR6A1 expressed in a system that normally lacks this protein.

• BLAST analysis: Review BLAST analysis results of the immunogen sequence to ensure no significant homology with other proteins that could cause cross-reactivity .

How does NR6A1 regulate lipid metabolism?

NR6A1 has emerged as an important regulator of lipid metabolism, particularly in hepatic cells:

Research has demonstrated that NR6A1 regulates lipogenic gene expression and lipid content in HepG2 cells through the mammalian target of rapamycin complex 1 (mTORC1) pathway . The regulatory mechanism involves:

• Transcriptional repression: As a transcriptional repressor, NR6A1 binds to specific DNA sequences in the promoters of target genes involved in lipid metabolism.

• Insulin signaling modulation: NR6A1 knockdown has been shown to enhance insulin-induced migration and proliferation in HepG2 cells, suggesting its involvement in insulin signaling pathways that regulate metabolic processes .

• Cell migration and proliferation: Experimental evidence indicates that NR6A1 knockdown slightly increases the migration and proliferation of HepG2 cells at basal levels, with significantly enhanced effects following insulin administration .

The interaction between NR6A1 and the mTORC1 pathway suggests potential therapeutic targets for metabolic disorders involving dysregulated lipid metabolism, though further research is needed to fully elucidate the molecular mechanisms and physiological significance of these interactions.

What role does lnc-Nr6a1 play in glycolytic enzyme regulation?

The long non-coding RNA lnc-Nr6a1, particularly its lnc-Nr6a1-1 isoform, serves as a molecular scaffold for glycolytic enzymes, representing an intriguing regulatory mechanism for cellular metabolism:

• Direct protein interaction: Through identification of direct RNA interacting proteins (iDRIP) technique, lnc-Nr6a1-1 has been shown to directly bind multiple glycolytic enzymes including ALDOA, ENO1, PKM, GAPDH, and LDHA .

• Scaffold function: The lnc-Nr6a1-1 isoform acts as a scaffold molecule for the assembly of these glycolytic enzymes, supporting substrate channeling for efficient glycolysis .

• Metabolic impact: Knockout of Lnc-Nr6a1 significantly reduces both basal glycolysis and compensatory glycolysis, effects that can be reversed by overexpression of the lnc-Nr6a1-1 isoform .

• Multi-enzyme complex formation: Coimmunoprecipitation experiments with UV-crosslinked extracts have demonstrated that lnc-Nr6a1-1 facilitates the formation of a glycolytic multi-enzymatic complex, which promotes enhanced catalytic efficiency .

• Additional enzyme recruitment: Beyond the initially identified enzymes, the complex also includes TPI1, PGAM1, and PGK1, further supporting the role of lnc-Nr6a1-1 as a comprehensive scaffold for glycolytic machinery .

This mechanism represents an important example of how lncRNAs can regulate metabolic processes through direct interaction with enzymes rather than through traditional transcriptional or post-transcriptional regulation.

What is the relationship between NR6A1 and microRNAs?

The NR6A1 gene locus exhibits a complex relationship with microRNAs through several mechanisms:

• miRNA hosting: Within intron 3 of the long NR6A1 isoform, there exists a polycistronic transcript that encodes miR-181a2 and miR-181b-2 microRNAs .

• Regulatory feedback: The common 3' untranslated region of NR6A1 transcripts harbors multiple microRNA binding sites, suggesting potential regulation of NR6A1 expression by microRNAs .

• lnc-Nr6a1 processing: When the lnc-Nr6a1 is processed, it gives rise to a longer non-polyadenylated microprocessor-driven lnc-pri-miRNA containing clustered pre-miR-181a2 and pre-miR-181b2 hairpins .

• Functional impact: Expression of lnc-Nr6a1 isoforms along with miR-181a2 and miR-181b2 confers anoikis resistance, suggesting coordinated functions in cell survival pathways .

This intricate relationship illustrates the multifunctional nature of the NR6A1 genomic locus, which produces protein-coding transcripts, regulatory lncRNAs, and microRNAs that may work in concert to coordinate biological processes including cell migration, adhesion, and metabolism.

What are the best practices for using NR6A1 antibodies in immunohistochemistry?

To achieve optimal results when using NR6A1 antibodies for immunohistochemistry (IHC), consider these methodological recommendations:

• Fixation optimization: Since NR6A1 is a nuclear protein, proper fixation is critical. Paraformaldehyde (4%) or formalin fixation with appropriate antigen retrieval methods helps maintain nuclear architecture while enabling antibody access to the epitope.

• Antigen retrieval: Heat-induced epitope retrieval (HIER) using citrate buffer (pH 6.0) or EDTA buffer (pH 9.0) is often effective for nuclear antigens like NR6A1. The optimal method should be determined empirically.

• Blocking protocol: Thorough blocking with appropriate serum (typically 5-10% normal serum from the same species as the secondary antibody) plus 0.1-0.3% Triton X-100 reduces background staining.

• Antibody dilution: Begin with the manufacturer's recommended dilution range and optimize through titration experiments. Anti-NR6A1 antibodies have been successfully used in IHC and IHC on paraffin-embedded sections .

• Incubation conditions: Overnight incubation at 4°C often yields better results than shorter incubations at room temperature for nuclear targets.

• Detection system selection: For low abundance targets, consider using amplification systems such as tyramide signal amplification (TSA) or polymer-based detection systems.

• Counterstaining: Use nuclear counterstains such as hematoxylin or DAPI at appropriate dilutions to visualize nuclei without obscuring NR6A1 staining.

• Controls: Always include positive and negative controls, including tissue known to express NR6A1 and samples where the primary antibody is omitted or pre-absorbed with immunizing peptide.

How can I design experiments to study NR6A1 function in metabolism?

When designing experiments to investigate NR6A1's role in metabolism, consider these methodological approaches:

• Gene manipulation strategies:

  • siRNA knockdown: Transfect cells with NR6A1-specific siRNA to reduce expression, as demonstrated in studies with HepG2 cells

  • CRISPR-Cas9 gene editing: Generate complete knockout or specific domain mutations

  • Overexpression studies: Compare wild-type and mutant NR6A1 constructs to identify functional domains

• Metabolic assessments:

  • Seahorse Analyzer measurements to determine glycolytic rates under basal conditions and following mitochondrial inhibition

  • Lipid content quantification using Oil Red O staining or other lipid quantification methods

  • Metabolomic profiling to identify changes in metabolite concentrations associated with NR6A1 manipulation

• Protein-protein interaction studies:

  • Coimmunoprecipitation with antibodies against NR6A1 or its putative interaction partners followed by mass spectrometry analysis

  • Proximity ligation assays to detect interactions in situ

  • UV crosslinking approaches such as iDRIP to identify direct RNA-protein interactions

• Transcriptional regulation assessment:

  • Chromatin immunoprecipitation (ChIP) to identify genomic binding sites

  • Luciferase reporter assays to quantify effects on gene expression

  • RNA-seq analysis following NR6A1 manipulation to identify regulated gene networks

• Functional readouts:

  • Cell migration assays such as wound-healing tests to assess effects on cell motility

  • Proliferation assays to determine effects on cell growth

  • Insulin signaling pathway analysis to understand metabolic regulation

What approaches can be used to study the interaction between lnc-Nr6a1 and glycolytic enzymes?

To investigate the interaction between lnc-Nr6a1 and glycolytic enzymes, researchers can employ these methodological approaches:

• Direct RNA-protein interaction techniques:

  • Identification of direct RNA interacting proteins (iDRIP): This in vivo technique involves UV crosslinking of cells, followed by purification of lnc-Nr6a1-protein complexes using antisense biotinylated oligonucleotides

  • RNA immunoprecipitation (RIP): Pull down RNA-protein complexes using antibodies against glycolytic enzymes

  • Crosslinking and immunoprecipitation (CLIP) methods to map interaction sites with nucleotide resolution

• Functional validation approaches:

  • Seahorse Analyzer measurements to quantify glycolytic rates under basal conditions and compensatory glycolysis following mitochondrial inhibition in control versus lnc-Nr6a1-depleted cells

  • Rescue experiments: Test whether overexpression of lnc-Nr6a1 isoforms can restore glycolytic function in knockout cells

  • Domain mapping: Create deletion constructs to identify the regions of lnc-Nr6a1 responsible for enzyme binding

• Multi-protein complex characterization:

  • Coimmunoprecipitation with antibodies against individual glycolytic enzymes (e.g., ENO-1) followed by quantitative mass spectrometry to identify associated proteins

  • Blue native PAGE to preserve native protein complexes for analysis

  • Size exclusion chromatography to isolate and characterize multi-enzyme complexes

• Microscopy-based techniques:

  • RNA-FISH combined with immunofluorescence to visualize co-localization of lnc-Nr6a1 and glycolytic enzymes

  • Live-cell imaging with fluorescently tagged components to track complex formation dynamics

  • Super-resolution microscopy to characterize the spatial organization of the glycolytic complex

• Enzymatic activity assays:

  • Comparative enzyme kinetics in the presence or absence of lnc-Nr6a1

  • Substrate channeling assessment to quantify the efficiency of sequential reactions in the glycolytic pathway

  • In vitro reconstitution experiments with purified components to demonstrate direct effects on enzyme activity

What are common issues when using NR6A1 antibodies and how can they be resolved?

Researchers working with NR6A1 antibodies may encounter several challenges:

• High background in immunostaining:

  • Cause: Insufficient blocking, excessive antibody concentration, or cross-reactivity

  • Solution: Increase blocking time/concentration, titrate antibody to optimal concentration, pre-absorb antibody with non-specific proteins, or use more stringent washing protocols

• Multiple bands in Western blot:

  • Cause: Detection of multiple isoforms, degradation products, or non-specific binding

  • Solution: Verify band sizes against known isoforms (NR6A1 has up to five reported isoforms ), include protease inhibitors during sample preparation, and optimize antibody concentration

• Inconsistent immunoprecipitation results:

  • Cause: Inefficient antibody binding, harsh elution conditions, or weak protein-protein interactions

  • Solution: Use antibodies validated for immunoprecipitation, optimize buffer conditions, consider crosslinking approaches for transient interactions

• Discrepancies between antibody results:

  • Cause: Different epitope recognition, isoform selectivity, or varying sensitivity

  • Solution: Compare antibodies recognizing different epitopes, verify results with orthogonal methods, and consider using pooled antibodies for comprehensive detection

• Poor signal in fixed tissues:

  • Cause: Epitope masking during fixation or processing

  • Solution: Optimize antigen retrieval methods, test multiple fixatives, or consider using fresh-frozen samples when possible

• Difficulty distinguishing NR6A1 isoforms:

  • Cause: Overlapping sequences between isoforms

  • Solution: Use isoform-specific antibodies when available, combine with RNA-based detection methods, or use genetic approaches to manipulate specific isoforms

How can I interpret contradictory results in NR6A1 research?

When faced with contradictory results in NR6A1 research, consider these interpretative approaches:

• Biological context differences:

  • Cell type specificity: NR6A1 function may vary between cell types due to different cofactor availability or signaling environments

  • Developmental stage variations: NR6A1 roles change throughout development, with knockouts being embryonic lethal

  • Species-specific differences: Despite high conservation (100% identity across many species ), subtle functional differences may exist

• Technical considerations:

  • Antibody specificity: Different antibodies may recognize distinct epitopes or isoforms

  • Knockdown efficiency: Partial versus complete knockdown may reveal different aspects of NR6A1 function

  • Experimental timing: Acute versus chronic manipulation may yield different results due to compensatory mechanisms

• Multi-functional nature of NR6A1:

  • Transcriptional versus non-transcriptional roles: While primarily a transcriptional repressor , NR6A1 may have additional functions

  • Isoform-specific effects: Different isoforms (up to five reported ) may have distinct or even opposing functions

  • Context-dependent interactions: NR6A1 may interact with different partners depending on cellular conditions

• Integration with lncRNA and miRNA functions:

  • Coordinate regulation: The NR6A1 locus produces protein-coding transcripts, lncRNAs, and miRNAs that may work together

  • Independent functions: Effects attributed to NR6A1 protein may sometimes result from associated non-coding RNAs

  • Feedback regulation: miRNAs produced from the NR6A1 locus may regulate NR6A1 itself

• Systematic validation approaches:

  • Orthogonal techniques: Confirm findings using multiple methodologies

  • Genetic complementation: Rescue experiments to verify specificity of observed phenotypes

  • Dose-response relationships: Test whether effects are proportional to NR6A1 levels