RESUMEN
Leishmaniasis is a spectrum of diseases caused by parasites of the genus Leishmania that affects millions of people around the world. During infection, the parasites use different strategies to survive the host's defenses, including overcoming exposure to reactive oxidant species (ROS), responsible for causing damage to lipids, proteins and DNA. This damage especially affects telomeres, which frequently results in genome instability, senescence and cell death. Telomeres are the physical ends of the chromosomes composed of repetitive DNA coupled with proteins, whose function is to protect the chromosomes termini and avoid end-fusion and nucleolytic degradation. In this work, we induced acute oxidative stress in promastigote forms of Leishmania amazonensis by treating parasites with 2mM hydrogen peroxide (H2O2) for 1h, which was able to increase intracellular ROS levels. In addition, oxidative stress induced DNA damage, as confirmed by 8-oxodGuo quantification and TUNEL assays and the dissociation of LaRPA-1 from the 3' G-overhang, leading to telomere shortening. Moreover, LaRPA-1 was observed to interact with newly formed C-rich single-stranded telomeric DNA, probably as a consequence of the DNA damage response. Nonetheless, acute oxidative stress caused the death of some of the L. amazonensis population and induced cell cycle arrest at the G2/M phase in survivor parasites, which were able to continue proliferating and replicating DNA and became more resistant to oxidative stress. Taken together, these results suggest that adaptation occurs through the selection of the fittest parasites in terms of repairing oxidative DNA damage at telomeres and maintaining genome stability in a stressful environment.
Asunto(s)
Adaptación Fisiológica/genética , Reparación del ADN , ADN Protozoario/genética , Peróxido de Hidrógeno/farmacología , Leishmania mexicana/efectos de los fármacos , Acortamiento del Telómero/efectos de los fármacos , Secuencia de Bases , Daño del ADN , ADN Protozoario/metabolismo , ADN de Cadena Simple/genética , ADN de Cadena Simple/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Puntos de Control de la Fase G2 del Ciclo Celular , Expresión Génica , Aptitud Genética , Leishmania mexicana/genética , Leishmania mexicana/crecimiento & desarrollo , Leishmania mexicana/metabolismo , Estrés Oxidativo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Especies Reactivas de Oxígeno/agonistas , Especies Reactivas de Oxígeno/metabolismo , Selección Genética , Estrés Fisiológico , Telómero/químicaRESUMEN
Leishmaniasis is a spectrum of diseases caused by parasites of the genus Leishmania that affects millions of people around the world. During infection, the parasites use different strategies to survive the host's defenses, including overcoming exposure to reactive oxidant species (ROS), responsible for causing damage to lipids, proteins and DNA. This damage especially affects telomeres, which frequently results in genome instability, senescence and cell death. Telomeres are the physical ends of the chromosomes composed of repetitive DNA coupled with proteins, whose function is to protect the chromosomes termini and avoid end-fusion and nucleolytic degradation. In this work, we induced acute oxidative stress in promastigote forms of Leishmania amazonensis by treating parasites with 2 mM hydrogen peroxide (H2O2) for 1 h, which was able to increase intracellular ROS levels. In addition, oxidative stress induced DNA damage, as confirmed by 8-oxodGuo quantification and TUNEL assays and the dissociation of LaRPA-1 from the 3' G-overhang, leading to telomere shortening. Moreover, LaRPA-1 was observed to interact with newly formed C-rich single-stranded telomeric DNA, probably as a consequence of the DNA damage response. Nonetheless, acute oxidative stress caused the death of some of the L. amazonensis population and induced cell cycle arrest at the G2/M phase in survivor parasites, which were able to continue proliferating and replicating DNA and became more resistant to oxidative stress. Taken together, these results suggest that adaptation occurs through the selection of the fittest parasites in terms of repairing oxidative DNA damage at telomeres and maintaining genome stability in a stressful environment.