Retinoic acid receptor alpha – corepressor complex (RARα-CoR complex)

The Retinoic acid receptor alpha (RARα) – corepressor complex is a multi-protein assembly that functions as a transcriptional repressor in the absence of its ligand, retinoic acid (Wikipedia, NIH). It typically consists of the RARα nuclear receptor, often heterodimerized with the Retinoid X Receptor (RXR), and corepressor proteins such as Nuclear Receptor Corepressor 1 (NCoR1) or Silencing Mediator for Retinoid and Thyroid Hormone Receptors (SMRT/NCOR2) (Journal of Biological Chemistry, Wikipedia). These corepressors recruit histone deacetylases (HDACs) to maintain a condensed, transcriptionally inactive chromatin state (ASH Publications, Onkoview). This complex is a primary driver of Acute Promyelocytic Leukemia (APL), where oncogenic fusion proteins like PML-RARα constitutively recruit corepressors to block the expression of genes required for myeloid differentiation (ASH Publications, NIH). Pharmacological treatment with all-trans retinoic acid (ATRA) induces a conformational shift in the receptor that triggers corepressor dissociation and coactivator recruitment, thereby restoring cell maturation (ASH Publications, Guide to Pharmacology). Additionally, the complex has been identified as an endogenous inhibitor of chaperone-mediated autophagy (CMA), making it a target for small molecules designed to stabilize the interaction and activate autophagic pathways in neurodegenerative and retinal diseases (Nature Communications, NIH).

Other names

RARα-NCoR complexRARα-SMRT complexRARα-NCOR1 complexRARα-NCOR2 complexPML-RARα-corepressor complexRXR-RARα-corepressor complexRetinoic acid receptor alpha-nuclear receptor corepressor complex

Drugs targeting this complex operate through several distinct mechanisms: 1) Retinoid agonists like Tretinoin (ATRA) bind to the RARα subunit, inducing a conformational change that triggers the dissociation of corepressors (NCoR/SMRT) and recruitment of coactivators to activate gene transcription (ASH Publications); 2) Arsenic trioxide induces the sumoylation and subsequent proteasomal degradation of the PML-RARα fusion protein within the complex (NIH); 3) HDAC inhibitors like Vorinostat block the activity of histone deacetylases recruited by the corepressors to relieve transcriptional silencing (ASH Publications); and 4) CMA activators stabilize the RARα-NCoR1 interaction to relieve the inhibition of chaperone-mediated autophagy (Nature Communications).