Promyelocytic leukemia protein-retinoic acid receptor alpha fusion protein (PML-RARA)

The **Promyelocytic leukemia protein-retinoic acid receptor alpha fusion protein** (PML-RARA) is a chimeric oncoprotein formed by the t(15;17)(q24;q21) chromosomal translocation, which fuses the **PML** gene on chromosome 15 to the **retinoic acid receptor alpha** (**RARA**) gene on chromosome 17. This fusion is the hallmark genetic lesion of **acute promyelocytic leukemia (APL)**. The PML-RARA protein combines domains from both PML and RARA, retaining functionalities such as DNA binding, RXR-binding, and protein oligomerization[2][4]. Functionally, it acts as a dominant repressive transcription factor that blocks the expression of genes necessary for normal myeloid differentiation. It disrupts nuclear body (NB) organization—key for apoptosis, senescence, and DNA repair—mainly by disorganizing PML nuclear bodies and repressing transcription of genes involved in differentiation and apoptosis[2][5]. Pharmacologically, PML-RARA is highly sensitive to pharmacological doses of **all-trans retinoic acid (ATRA)** and **arsenic trioxide (ATO)**. ATRA induces differentiation of leukemic promyelocytes by alleviating transcriptional repression, while ATO degrades the fusion protein via direct interaction with cysteine residues in the PML portion, particularly C213[3]. Detection of the PML-RARA transcript serves as a definitive diagnostic and minimal residual disease marker in APL[6][8]. Resistance can develop through point mutations, especially those affecting the ATO binding site or ATRA response elements[1][3]. The fusion protein is central to the pathogenesis of APL and a major therapeutic target that has enabled highly effective, targeted treatments for this leukemia subtype.

Other names

Promyelocytic leukemia protein-retinoic acid receptor alpha fusion proteinPML-RARA fusion proteinPML/RARAPML-RARα

All-trans retinoic acid (ATRA): Overcomes transcriptional repression by causing the fusion protein to release corepressors, enabling the expression of genes required for differentiation of promyelocytes. Arsenic trioxide (ATO): Induces degradation of the fusion protein by targeting specific cysteine residues (notably C213 in the PML moiety), promoting sumoylation and proteolysis.