RESUMEN
Treacher Collins syndrome-3 (TCS-3) is a rare congenital craniofacial disorder attributed to variants in the RNA pol I subunit C (POLR1C). The pathogenesis of TCS-3 linked to polr1c involves the activation of apoptosis-dependent p53 pathways within neural crest cells (NCCs). This occurs due to disruptions in ribosome biogenesis, and the restoration of polr1c expression in early embryogenesis effectively rescues the observed craniofacial phenotype in polr1c-deficient zebrafish. Clinical variability in TCS patients suggests interactions between genes and factors like oxidative stress. Elevated production of reactive oxygen species (ROS) in epithelial cells may worsen phenotypic outcomes in TCS individuals. Our study confirmed excessive ROS production in facial regions, inducing apoptosis and altering p53 pathways. Deregulated cell-cycle and epithelial-to-mesenchymal transition (EMT) genes were also detected in the TCS-3 model. Utilizing p53 inhibitor (Pifithrin-α; PFT-α) or antioxidants (Glutathione; GSH and N-Acetyl-L-cysteine; NAC) effectively corrected migrated NCC distribution in the pharyngeal arch (PA), suppressed oxidative stress, prevented cell death, and modulated EMT inducers. Crucially, inhibiting p53 activation or applying antioxidants within a specific time window, notably within 30 h post-fertilization (hpf), successfully reversed phenotypic effects induced by polr1c MO.
Asunto(s)
Antioxidantes , Benzotiazoles , Modelos Animales de Enfermedad , Disostosis Mandibulofacial , Estrés Oxidativo , Especies Reactivas de Oxígeno , Tolueno/análogos & derivados , Proteína p53 Supresora de Tumor , Proteínas de Pez Cebra , Pez Cebra , Animales , Proteína p53 Supresora de Tumor/metabolismo , Proteína p53 Supresora de Tumor/genética , Disostosis Mandibulofacial/genética , Disostosis Mandibulofacial/tratamiento farmacológico , Antioxidantes/farmacología , Benzotiazoles/farmacología , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismo , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Transición Epitelial-Mesenquimal/efectos de los fármacos , Tolueno/farmacología , Cresta Neural/efectos de los fármacos , Cresta Neural/metabolismo , Apoptosis/efectos de los fármacos , ARN Polimerasa I/antagonistas & inhibidores , ARN Polimerasa I/metabolismo , ARN Polimerasa I/genéticaRESUMEN
In cancer therapy, DNA intercalators are mainly known for their capacity to kill cells by inducing DNA damage. Recently, several DNA intercalators have attracted much interest given their ability to inhibit RNA Polymerase I transcription (BMH-21), evict histones (Aclarubicin) or induce chromatin trapping of FACT (Curaxin CBL0137). Interestingly, these DNA intercalators lack the capacity to induce DNA damage while still retaining cytotoxic effects and stabilize p53. Herein, we report that these DNA intercalators impact chromatin biology by interfering with the chromatin stability of RNA polymerases I, II and III. These three compounds have the capacity to induce degradation of RNA polymerase II and they simultaneously enable the trapping of Topoisomerases TOP2A and TOP2B on the chromatin. In addition, BMH-21 also acts as a catalytic inhibitor of Topoisomerase II, resembling Aclarubicin. Moreover, BMH-21 induces chromatin trapping of the histone chaperone FACT and propels accumulation of Z-DNA and histone eviction, similarly to Aclarubicin and CBL0137. These DNA intercalators have a cumulative impact on general transcription machinery by inducing accumulation of topological defects and impacting nuclear chromatin. Therefore, their cytotoxic capabilities may be the result of compounding deleterious effects on chromatin homeostasis.