Thyroid hormone receptor alpha 1 (TRα1) (TRα1)

Thyroid hormone receptor alpha 1 (TRα1) is a nuclear hormone receptor and transcription factor encoded by the THRA gene [UniProt, Wikipedia]. It is the predominant thyroid hormone receptor isoform in the heart, skeletal muscle, and central nervous system, where it mediates the genomic actions of triiodothyronine (T3) [NIH, ResearchGate]. TRα1 plays a critical role in regulating heart rate, metabolic rate, and skeletal development [NIH, Wikipedia]. Mutations in the THRA gene lead to Resistance to Thyroid Hormone alpha (RTHα), a condition characterized by tissue-specific hypothyroidism, growth retardation, and bradycardia despite near-normal systemic thyroid hormone levels [NIH, Orphanet]. Pharmacological modulation of TRα1 is being explored for treating cardiovascular and metabolic conditions, although achieving tissue selectivity is a major challenge to avoid adverse effects such as tachycardia and bone mineral density loss [Patsnap, Frontiers in Endocrinology].

Other names

THRANR1A1ERBA1c-erbA-1c-erbA-alphaNuclear receptor subfamily 1 group A member 1Thyroid hormone receptor alphaTriiodothyronine receptor

TRα1 acts as a ligand-activated transcription factor. In the absence of thyroid hormone (T3), it binds to thyroid hormone response elements (TREs) in the promoter regions of target genes and recruits corepressor complexes (e.g., NCoR, SMRT) to inhibit transcription. Upon T3 binding, the receptor undergoes a conformational change that leads to the dissociation of corepressors and the recruitment of coactivator complexes (e.g., SRC-1), thereby initiating the transcription of genes involved in metabolism, cardiac function, and development [UniProt, NIH, ResearchGate].