The Dual Roles of Reactive Oxygen Species during Erythropoiesis and the Effect of Salidroside on Erythropoesis and Erythrocytes.

摘要

Reactive oxygen species (ROS) have been considered to be deleterious to cells; however, increasing evidence demonstrates that they actually play dual roles. Unchecked high amounts of ROS can damage cellular components, whereas moderately well-regulated ROS play crucial roles as signaling messengers in the regulation of various biological processes. For example, ROS contribute significantly to the differentiation of hematopoietic cells, but the underlying mechanisms remain unresolved. Previous work of our laboratory has revealed that ROS was produced and contributed to the establishment of the antioxidant defense system during erythropoietin (EPO)-induced erythropoiesis in TF-l cells. In the present study, the roles of ROS during erythroid maturation were further investigated and the effect of an antioxidant salidroside (SDS) on erythropoiesis or erythrocytes was examined.;Salidroside (SDS) is a widely used adaptogen and blood tonic supplement in traditional medicine for the treatment of high altitude sickness, anoxia and mountain malhypoxia. Here we show for the first time that SDS (100 muM) promoted erythroid differentiation and was able to protect erythroblasts against H202 to commit cell death through apoptosis. The protective effect of SDS was contributed by the up-regulation of anti-oxidative proteins. Furthermore, SDS was also found to be able to rescue human erythrocytes from apoptosis induced by oxidative stress. The rescue effect was largely through the anti-oxidative effect, suppression of [Ca2+]i rise and caspases-3 activation. These findings show the mechanism underlying the use of SDS and confirm the application of it as an antioxidant or blood tonic to enhance body's resistance to stress and fatigue.;Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme of anti-oxidative defense system of red blood cells (RBCs). G6PD deficiency affects more than 400 million people worldwide. Employing RNAi technology (miRNA), we developed a stable G6PD-knockdown TF-1 cell line. Using these G6PD-knockdown cells, we found that the efficacy of erythroid cells production during erythropoiesis was decreased, whereas the ROS production and apoptotic frequency were increased. Moreover, other important antioxidant enzymes such as glutathione peroxidase 1 (GPx1) and thioredoxin-1 (Trx1) were found to be down-regulated in the G6PD-knockdown cells, indicating G6PD plays a role in the regulation of these two antioxidant enzymes. Besides, SDS (100 muM) was shown to be able to protect G6PD-knockdown erythroblasts from the H2O2-induced oxidative stress.;Glucose transporter type 1 (Glut1) mediates the uptake of glucose that provides the major reducing equivalents in human erythrocytes. We found that Glut1 was up-regulated during erythropoiesis in TF-1 cells and reduction in ROS level resulted in a decrease in Glut1 level. Furthermore, elevated ROS up-regulated Glut1 and hypoxia-inducible factor-1alpha (HIF-1alpha), and inhibition of HIF-1alpha suppressed the up-regulation of Glut1. Taken together, these observations indicate that ROS regulate Glut1 expression through the HIF-1alpha during erythropoiesis in TF-1 cells.;In conclusion, the findings of this study (1) provide support for therapeutic applications of SDS in preventing anemia after cancer chemotherapy and treating G6PD deficiency disease; (2) elucidate the role of G6PD during erythropoiesis, thereby contributing to the treatment of G6PD deficiency disease; and (3) further explore the role of ROS and its regulation on Glut1 via HIF-1alpha in erythropoiesis.