ESR2 Antibody

What is ESR2 and what are its key structural characteristics?

ESR2 is a nuclear hormone receptor protein with a reported length of 530 amino acid residues and a molecular weight of approximately 59.2 kDa in humans. It belongs to the Nuclear hormone receptor protein family and functions primarily in the nucleus. Up to 9 different isoforms have been reported for this protein, which is notably expressed in the adrenal gland. ESR2 participates in cell-to-cell signaling and regulation of cell growth, and can undergo post-translational modifications including phosphorylation .

How does ESR2 distribution differ from ESR1?

While both are estrogen receptors, ESR1 (estrogen receptor alpha) is expressed in more than 75% of breast tumors and serves as a key biomarker for directing endocrine therapies. In contrast, ESR2 is generally expressed at lower levels in breast cancer with a slight inverse correlation to ESR1 expression (Spearman R = −0.18, p = 2.2e−16). ESR2 shows highest expression in the basal-like and normal-like PAM50 breast cancer subtypes. Additionally, ESR2 has a more localized tissue distribution pattern than previously thought based on studies using validated antibodies .

What are the common synonyms and orthologs for ESR2?

Researchers should be aware of multiple naming conventions when searching literature. Common synonyms include ESR-BETA, ESRB, ESTRB, Erb, NR3A2, ODG8, estrogen receptor beta, and ER-BETA. ESR2 gene orthologs have been documented in mouse, rat, bovine, frog, zebrafish, chimpanzee, and chicken species, making it important to clarify the species-specific context in cross-species research .

Why has ESR2 research been hampered by antibody validation issues?

ESR2 research represents a notorious example of data distortion caused by inadequately validated antibodies. The absence of reliable specific antibodies has severely hindered progress in understanding ESR2 biology. Previous studies using such antibodies likely overestimated ESR2 distribution profiles, leading to conflicting results and interpretations within the scientific literature .

What breakthroughs have occurred in ESR2 antibody validation?

A significant advancement came in 2017 with the identification of a specific anti-human ESR2 monoclonal antibody (PPZ0506). This antibody has been validated for cross-reactivity against rodent ESR2 proteins, enabling researchers to elucidate the true distribution of ESR2 in rodents. The validation of this antibody has helped resolve some contradictory findings in ESR2 research .

How can researchers confirm the specificity of their ESR2 antibodies?

Researchers should implement a multi-faceted validation approach:

• Test antibodies on tissues with known ESR2 expression (e.g., ovary)

• Include negative controls (tissues lacking ESR2 expression)

• Compare staining patterns across multiple validated antibodies

• Verify correlation between protein detection and mRNA expression

• Use appropriate antigen retrieval methods and blocking procedures

• Validate across multiple experimental techniques (WB, IHC, IF)

• Consider using the validated PPZ0506 antibody as a reference standard

What are the optimal conditions for immunohistochemical detection of ESR2 in rat tissues?

Based on research using the validated PPZ0506 antibody, optimal detection requires:

• Appropriate heat-induced antigen retrieval

• Careful antibody dilution optimization

• Proper blocking of non-specific binding sites

• Use of validated positive controls (e.g., ovary sections)

These optimized conditions have revealed that rat ESR2 proteins are expressed in a more localized manner than previously assumed, highlighting the importance of methodological rigor .

How should mouse-on-mouse immunohistochemical detection of ESR2 be optimized?

For optimal mouse-on-mouse immunohistochemical detection using PPZ0506:

• Intense heat-induced antigen retrieval is necessary

• Apply appropriate blocking to prevent non-specific binding

• Determine optimal antibody dilutions through titration experiments

• Use paraffin-embedded sections with proper preparation techniques

This optimization has demonstrated that mouse ESR2 proteins have a more localized distribution than previously thought, with interspecies differences when compared to humans and rats .

What applications are most reliable for ESR2 antibody detection?

ESR2 antibodies have been validated for multiple applications including:

Researchers should select applications based on the specific validation data available for their chosen antibody .

What is the prognostic significance of ESR2 expression in breast cancer?

• Patients receiving endocrine therapy (p = 0.03)

• Triple-negative breast cancer cases (p = 0.01)

These associations remained robust in multivariable analyses accounting for patient age, tumor size, node status, and grade .

How does ESR2 expression correlate with breast cancer molecular subtypes?

RNA-seq analysis from the SCAN-B study revealed:

This differential expression pattern suggests potential subtype-specific roles for ESR2 in breast cancer biology and treatment response .

What molecular mechanisms might explain the favorable prognosis associated with high ESR2 expression?

Gene expression analysis has revealed that ESR2-high tumors are associated with immune response-related gene modules. This suggests ESR2 may influence prognosis through immune response modulation. The relationship between ESR2 and immune function provides researchers with potential directions for investigating how ESR2 impacts cancer progression and treatment response .

How does ESR2 expression differ between humans, mice, and rats?

Studies using the validated PPZ0506 antibody have demonstrated significant interspecies differences in ESR2 expression patterns:

These findings highlight the importance of species-specific validation when studying ESR2 and caution against direct extrapolation across species .

What tissues reliably express ESR2 proteins across species?

Using optimized immunohistochemical detection with validated antibodies:

• Ovarian granulosa cells show consistent ESR2 expression across species

• Endothelial cells in specific vascular beds express ESR2

• Select neuronal populations in the central nervous system express ESR2

• Epithelial cells in certain tissues demonstrate species-specific ESR2 expression

The more restricted expression pattern revealed by validated antibodies suggests more specialized functions for ESR2 than previously thought .

How do ESR2 isoforms complicate cross-species research?

The presence of up to 9 different isoforms of ESR2 significantly complicates comparative studies:

• Isoform expression patterns vary between tissues and species

• Different antibodies may recognize specific isoforms preferentially

• Functional significance of isoforms may differ between species

• Experimental detection methods vary in sensitivity to different isoforms

Researchers must account for these variables when designing cross-species studies and interpreting results .

How can researchers overcome the challenges of detecting low-level ESR2 expression?

ESR2 is often expressed at low levels, requiring optimization strategies:

• Implement signal amplification methods (e.g., tyramide signal amplification)

• Use highly sensitive detection systems (e.g., polymer-based secondary antibodies)

• Optimize antigen retrieval for maximum epitope accessibility

• Employ longer primary antibody incubation times at optimized temperatures

• Consider the use of biotin-free detection systems to reduce background

• Include proper positive controls with known expression levels

What controls are essential for reliable ESR2 antibody-based experiments?

A robust control system should include:

• Positive tissue controls (e.g., ovary sections with known ESR2 expression)

• Negative tissue controls (tissues lacking ESR2 expression)

• Antibody controls (omission of primary antibody, isotype controls)

• Blocking peptide controls where available

• Comparison with ESR2 mRNA expression data

• Internal controls within sections (e.g., positive and negative cell types)

What new technologies are improving ESR2 protein research?

Recent technological advances enhancing ESR2 research include:

• Single-cell protein analysis techniques for heterogeneous tissue examination

• Proximity ligation assays for detecting protein-protein interactions

• Multi-spectral imaging for simultaneous detection of multiple markers

• CRISPR-based genomic tagging for endogenous ESR2 visualization

• Mass spectrometry-based proteomics for isoform-specific detection

• Tissue clearing and 3D imaging techniques for whole-organ ESR2 mapping

These technologies offer promising approaches to overcome the historical challenges in ESR2 research .