Cardiac fibroblast-derived GNL3 aggravates acute doxorubicin-induced cardiac injury via FasL-linked fibroblast–cardiomyocyte crosstalk

Doxorubicin (DOX)-induced cardiac injury remains a major clinical challenge in oncology, with limited preventive strategies beyond dexrazoxane. Although cardiomyocyte-centered mechanisms dominate current understanding, the contribution of cardiac fibroblasts (CFs) remains incompletely defined. G protein nucleolar 3 (GNL3), a nucleolar GTP-binding protein implicated in tumor biology, has not been functionally characterized in DOX-related cardiac injury. To investigate its role, we generated cardiac fibroblast-specific GNL3 knockout (GNL3 cfKO ) and overexpression (GNL3 cfTg ) mice and subjected them to a single intraperitoneal injection of DOX (15 mg/kg) as an acute injury model. Mechanistic analyses included western blotting, RT-qPCR, immunofluorescence, co-immunoprecipitation, chromatin immunoprecipitation, conditioned medium (CM) assays, and echocardiographic assessment of cardiac function. GNL3 expression was markedly increased in DOX-treated murine hearts and was enriched in the fibroblast fraction. CF-specific deletion of GNL3 attenuated myocardial injury, oxidative stress, apoptosis, and systolic dysfunction, whereas CF-specific overexpression of GNL3 exacerbated these abnormalities and reduced survival. In contrast, cardiomyocyte-specific GNL3 deletion did not confer an obvious protective effect. In vitro, GNL3 manipulation in fibroblasts altered injury-associated readouts in cardiomyocytes exposed to conditioned medium derived from DOX-treated CFs. FasL emerged as an important contributor in this process, and GNL3 was functionally linked to the CaN/NFATc1 axis and increased NFATc1 occupancy at the Fasl promoter in cardiac fibroblasts. Overall, these data support a cardiac fibroblast-centered model in which GNL3 contributes to acute DOX-induced cardiac injury and is associated with FasL-linked fibroblast–cardiomyocyte crosstalk. These findings nominate CF-derived GNL3 as a candidate pathway for further investigation in anthracycline-associated cardiac injury. Doxorubicin induces GNL3 upregulation in cardiac fibroblasts, which is associated with CaN/NFATc1 activation, increased Fasl transcription, and enhanced FasL secretion. Fibroblast-derived FasL then promotes cardiomyocyte apoptosis, oxidative stress, and cardiac dysfunction through fibroblast–cardiomyocyte crosstalk