Ischemia-induced oxidative stress triggers DNA double strand breaks leading to neuronal apoptosis

Resumen de la conferencia invitada presentada en el 43rd Annual Meeting of the SEBBMThe maintenance of DNA integrity is essential for neuronal homeostasis. Increased oxidative stress and DNA double strand break (DSB) generation occur in neurological diseases, including neurodegenerative diseases and stroke [1]. However, the interplay between both phenomena and their implication in neuronal death is largely unknown.Here, we aim to investigate the impact of ischemia-induced DNA DSB on neuronal death and the role played by oxidative stress on DNA repair. For this purpose, mouse cortical neuron in primary culture were exposed to an experimental model of ischemia in vitro (oxygen-glucose deprivation, OGD) for 30 minutes followed by 4 hours of reoxygenation [1]. Next, we evaluated DNA DSB generation, protein expression and neuronal apoptosis by using western blot, flow cytometry, and immunostaining. We found that OGD time-dependently increased the expression of the DNA DSB marker, phospho-H2AX [2], which paralleled with a higher expression levels of apoptotic markers, active caspase-3 and p53. Moreover, OGD promoted oxidative stress and neuronal apoptosis, as revealed by the increase in both annexin/7AAD staining and TUNEL assay. Finally, to study the implication of oxidative stress in DNA damage, we used neuronal cultures from embryo mice that constitutively express the catalase in the mitochondria (mCAT), which downmodulates the endogenous generation of reactive oxygen species [3]. We found that mCAT neurons were more resistant to OGD-induced DNA damage and neuronal apoptosis than wild type neurons. Our results demonstrate that oxidative stress might play an important role in DNA DSB generation, which is involved in neuronal apoptosis caused by ischemia.SCIII: PI18/00103;PI18/00285;RD16/0019/0018; FEDER European regional development fund; JCyL: CSI151P20; CLU201703 P.O.FEDER CyL1420 and EDU/556/2019