Mouse embryonic fibroblasts from CD38 knockout mice are resistant to oxidative stresses through inhibition of reactive oxygen species production and Ca2+ overload

► CD38-deficient MEFs were more resistant to oxidative stress than WT MEFs. ► CD38-knockout appeared to block the production of ROS and elevation of Nox1 mRNA level after hypoxia/reoxygenation. ► CD38-knockout blocked the burst of [Ca2+]i induced by oxidative stress in MEFs. ► The transcriptional activity of Nox1 may be positively influenced by intracellular [Ca2+]. ► The lower expression of Nox1 mRNA in CD38–/– MEFs during oxidative stress might be contributed by a lower [Ca2+]i. CD38 is a multifunctional enzyme that has both ADP-ribosyl cyclase and cADPR hydrolase activities, being capable of cleaving NAD+ to cyclic ADP ribose (cADPR) and hydrolyzing cADPR to ADPR. It has been reported that there is markedly a reduction of cADPR and elevation of NAD in many tissues from CD38 knockout (CD38−/−) mice. Cyclic ADPR is a potent second messenger for intracellular Ca2+ mobilization, and NAD is a key cellular metabolite for cellular energetic and a crucial regulator for multiple signaling pathways in cells. We hypothesize that CD38 knockout may have a protective effect in oxidative stresses through elevating NAD and decreasing cADPR. In the present study, we observed that the mouse embryonic fibroblasts (MEFs) from CD38−/− mice were significantly resistant to oxidative stress such as H2O2 injury and hypoxia/reoxygenation compared with wild type MEFs (WT MEFs). We further found that production of reactive oxygen species (ROS) and concentrations of intracellular Ca2+ ([Ca2+]i) in CD38−/− MEFs were markedly reduced compared with WT MEFs during hypoxia/reoxygenation. Coincidence with these results, a remarkably lower mRNA level of Nox1, one of the enzymes responsible for ROS generation, was observed in CD38−/− MEFs. Furthermore, we found that transcription of Nox1 mRNA in WT MEFs could be elevated by calcium ionophore ionomycin in a dose-dependent manner, indicating that the expression of Nox1 mRNA can be regulated by elevation of intracellular [Ca2+]. Therefore we concluded that CD38−/− MEFs are resistant to oxidative stresses through inhibiting intracellular Ca2+ overload and ROS production which may be regulated by Ca2+-mediated inhibition of Nox1 expression. Our data should provide an insight for elucidating the roles of CD38 in oxidative stresses and a novel perspective of dealing with the ischemia/reperfusion-related diseases.