Preservation of ALYREF Phase Separation Mitigates Doxorubicin-Induced Cardiomyocyte DNA Damage and Cardiotoxicity.

The clinical utility of the anticancer agent doxorubicin (DOX) is limited by its dose-dependent cardiotoxicity. ALYREF, a nuclear protein that preserves genomic stability through interactions with intranuclear components or as an m⁵C-binding regulator of mRNA maturation and export, has not been previously implicated in DOX-induced cardiotoxicity (DIC). Here, the role and underlying mechanisms of ALYREF in the pathogenesis of DIC are investigated. The findings demonstrate that ALYREF expression is markedly reduced in a murine model of DIC. Myocardial-specific overexpression of ALYREF attenuates DOX-induced DNA damage and cardiomyocyte apoptosis, whereas cardiac-specific knockout of ALYREF (ALYREF CKO) exacerbates DOX-induced cardiac dysfunction. Mechanistically, it is identified that nuclear DOX directly binds to the aspartate residue (D171) within the intrinsically disordered regions (IDRs) of ALYREF, disrupting its liquid-liquid phase separation (LLPS) and promoting its ubiquitin-mediated degradation. The condensate state of ALYREF is essential for maintaining the integrity of the NORAD-activated ribonucleoprotein complex 1 (NARC1). Consequently, disruption of ALYREF LLPS leads to dissociation of the NARC1 complex, resulting in DNA damage and apoptosis in CMs. Collectively, these findings reveal a previously unrecognized mechanism by which DIC via interference with ALYREF condensates, offering new insight into the molecular basis of DIC.