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Abstract: The pathophysiology of oxidative hemolytic anemia is closely associated with hemoglobin (Hb) stability; however, the mechanism of how Hb maintains its stability under oxidative stress conditions of red blood cells (RBCs) carrying high levels of oxygen is unknown. Here, we investigated the potential role of peroxiredoxin II (Prx II) in preventing Hb aggregation induced by reactive oxygen species (ROS) using Prx II knockout mice and RBCs of patients with hemolytic anemia. Upon oxidative stress, ROS and Heinz body formation were significantly increased in Prx II knockout RBCs compared to wild-type (WT), which ultimately accelerated the accumulation of hemosiderin and heme-oxygenase 1 in the Prx II knock-out livers. In addition, ROS-dependent Hb aggregation was significantly increased in Prx II knockout RBCs. Interestingly, Prx II interacted with Hb in mouse RBCs, and their interaction, in particular, was severely impaired in RBCs of patients with thalassemia (THAL) and sickle cell anemia (SCA). Hb was bound to the decameric structure of Prx II, by which Hb was protected from oxidative stress. These findings suggest that Prx II plays an important role in preventing hemolytic anemia from oxidative stress by binding to Hb as a decameric structure to stabilize it. [Copyright &y& Elsevier]

Abstract: Erythroid cells are highly prone to oxidative damage generated during erythropoiesis and thus are well equipped with antioxidant defense systems. However, their roles have been poorly characterized. Here, we investigated the role of peroxiredoxin II in mouse erythropoiesis. Loss of Prx II significantly increased apoptosis and cell cycle arrest leading to abnormal erythropoiesis at 3weeks of age when erythropoietin levels were almost same between wild type and Prx II−/−. In Prx II−/− bone marrow cells, DNA tail length as an indicator of the oxidative damage was greatly increased and mRNAs of the molecules associated with DNA damage and repair and transcription regulators of antioxidant enzymes were also significantly increased. In addition, N-Acetyl-l-Cysteine treatment significantly decreased immature erythroblasts and apoptotic cells increased in Prx II−/− BMCs. These results strongly demonstrate that Prx II plays an essential role in maintaining normal erythropoiesis by protecting DNA damage. [Copyright &y& Elsevier]