Promyelocytic leukemia-retinoic acid receptor alpha (PML-RARα) oncoprotein complex (PML-RARα)

The PML-RARα oncoprotein complex is the pathognomonic driver of acute promyelocytic leukemia (APL), arising from a reciprocal translocation between chromosomes 15 and 17 (PMID: 11544150). This fusion protein acts as a dominant-negative repressor of retinoic acid receptor alpha (RARα) signaling by recruiting corepressor complexes, specifically those containing the Silencing Mediator for Retinoid and Thyroid hormone receptors (SMRT/NCOR2) and histone deacetylases (HDACs). These SMRT-containing complexes maintain target genes in a transcriptionally silenced state, effectively blocking the differentiation of myeloid progenitor cells at the promyelocyte stage (PMID: 10581234). Targeted therapy with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) works by either inducing the dissociation of these corepressors or promoting the degradation of the PML-RARα protein itself, respectively (PMID: 24651013). This dual-targeted approach has revolutionized APL treatment, shifting the clinical outcome from high mortality to high cure rates.

Other names

PML-RARA fusion proteint(15;17) translocation productPML-RARalphaPML-RARα/SMRT complexPML-RARα/NCOR2 complex

All-trans retinoic acid (ATRA) binds to the RARα moiety of the fusion protein, inducing a conformational change that triggers the release of SMRT-containing corepressor complexes and the recruitment of coactivators, thereby restoring the transcription of genes required for myeloid differentiation (PMID: 24651013). Arsenic trioxide (ATO) binds directly to the PML moiety, promoting its SUMOylation and subsequent RNF4-mediated ubiquitination and proteasomal degradation, which clears the oncoprotein from the cell (PMID: 20378815).