GO:0035259 obsolete nuclear glucocorticoid receptor binding

Gene Ontology (GO) term GO:0035259, obsolete nuclear glucocorticoid receptor binding, was once used to annotate molecular functions involving binding to the glucocorticoid receptor (GR) when it was thought to reside primarily in the nucleus. The glucocorticoid receptor, encoded by NR3C1, is a ligand-activated transcription factor that translocates from the cytoplasm to the nucleus upon hormone binding, where it regulates gene expression. The term was made obsolete because the 'nuclear' qualifier is inaccurate: GR is not exclusively nuclear, and binding events occur in multiple cellular compartments. This obsolescence reflects the dynamic nature of GO curation, which continuously updates terms to reflect current knowledge. For researchers, understanding why GO:0035259 was retired is essential for correct annotation and interpretation of high-throughput data, as using obsolete terms can lead to misleading functional enrichment results. The glucocorticoid receptor itself remains a major focus in pharmacology and disease biology, with selective modulators like Compound A offering tissue-specific effects. Thus, while GO:0035259 is no longer active, the biology it once described continues to be intensely studied, and modern tools such as CRISPR gene editing are used to dissect GR function and its interacting partners.

GO:0035259 (obsolete nuclear glucocorticoid receptor binding) was defined as the molecular function of binding to a nuclear glucocorticoid receptor. It was classified under molecular_function and had the synonym 'glucocorticoid receptor binding'. The term has been obsoleted because the glucocorticoid receptor is not exclusively nuclear; it shuttles between cytoplasm and nucleus, and binding interactions can occur in various cellular compartments. Therefore, annotations should now use updated terms such as GO:0035258 (glucocorticoid receptor binding) or other appropriate binding terms.

Although GO:0035259 is obsolete, the biological process it described, binding to the glucocorticoid receptor, is central to understanding glucocorticoid signaling, which regulates development, metabolism, immune response, and stress. The glucocorticoid receptor (NR3C1) is a major drug target, and its interactions with cofactors and heat shock proteins are critical for its function. Selective glucocorticoid receptor modulators (SEGRMs) like Compound A can enhance specific gene promoters such as Hsp70, demonstrating the therapeutic potential of targeting GR interactions. Accurate annotation of GR binding is essential for interpreting genomic data, and obsolete terms like GO:0035259 must be replaced to avoid errors. Furthermore, CRISPR-based models are now used to study GR function and its binding partners, linking basic GO annotations to experimental validation.

The following genes and proteins are central to glucocorticoid receptor binding and signaling, as supported by the cited literature.

The glucocorticoid receptor (GR) is regulated at multiple levels. Its activity is controlled by ligand availability, which is influenced by 11β-hydroxysteroid dehydrogenase enzymes. Chaperone proteins, including Hsp90 and Hsp70, regulate GR folding and ligand-binding affinity. Compound A, a selective GR modulator, can differentially regulate GR target genes such as Hsp70, indicating that GR-mediated transcription is subject to pharmacological modulation. Additionally, post-translational modifications (phosphorylation, ubiquitination, sumoylation) affect GR stability, subcellular localization, and transcriptional activity. Feedback loops involving FKBP5 and other co-chaperones fine-tune GR sensitivity. These regulatory mechanisms ensure that GR responses are context-dependent and tissue-specific.

Glucocorticoids are widely used to treat inflammatory conditions, and their effects are mediated by GR. The obsolete term GO:0035259 was once used to annotate GR binding in the nucleus, but modern research shows that GR interacts with NF-kB and AP-1 to repress inflammatory genes. Selective GR modulators like Compound A aim to separate anti-inflammatory benefits from side effects, highlighting the therapeutic importance of GR binding interactions.

GR signaling plays complex roles in cancer, with context-dependent effects on proliferation and apoptosis. In some cancers, GR activation promotes survival, while in others it induces cell death. The binding of GR to cofactors and other transcription factors influences these outcomes. Understanding GR interactions is crucial for developing targeted therapies, and CRISPR screens can identify synthetic lethal partners.

GR regulates glucose metabolism, fat distribution, and stress responses. Dysregulation of GR signaling is linked to Cushing's syndrome, metabolic syndrome, and depression. The obsolete term GO:0035259 reflects an outdated view of GR as solely nuclear, but its cytoplasmic actions also contribute to metabolic regulation. Research into GR binding partners may reveal new drug targets.

ChIP-seq is used to map GR binding sites across the genome. By immunoprecipitating GR or tagged GR, researchers can identify GREs and other binding regions. This method is essential for understanding the genomic actions of GR and for validating the obsolete term's original intent.

RNA-seq measures changes in gene expression upon GR activation or modulation. It can reveal how selective GR modulators like Compound A affect target genes such as Hsp70. Comparing wild-type and GR-knockout cells identifies GR-dependent transcriptional programs.

Affinity purification coupled with mass spectrometry (AP-MS) identifies GR-interacting proteins, including heat shock proteins and cofactors. These studies help define the GR interactome and its dynamics under different conditions.

CRISPR knockout, knock-in, and overexpression models are used to dissect GR signaling. For example, knocking out NR3C1 abolishes glucocorticoid responses, while knock-in of tagged GR allows imaging and binding studies. Library screening can identify modifiers of GR activity.

Researchers studying obsolete nuclear glucocorticoid receptor binding-related genes often need to determine whether a candidate gene is causally involved in GR signaling or disease. EDITGENE provides comprehensive CRISPR services to generate precisely engineered cell models, enabling functional validation of GR interactions and their role in health and disease.

GO:0035259 (obsolete nuclear glucocorticoid receptor binding) serves as a reminder of how scientific understanding evolves. While the term is no longer active, the biology of glucocorticoid receptor binding remains a vibrant field with implications for inflammation, cancer, and metabolism. Researchers should use updated GO terms and leverage modern CRISPR tools to explore GR interactions. EDITGENE offers a full suite of CRISPR services to support this research, from knockout to library screening, helping to translate basic findings into therapeutic insights.