Global analysis of erythroid cells redox status reveals the involvement of Prdx1 and Prdx2 in the severity of beta thalassemia

Abstract

β-thalassemia is a worldwide distributed monogenic red cell disorder, characterized by an absent or reduced beta globin chain synthesis. The unbalance of alpha-gamma chain and the presence of pathological free iron promote severe oxidative damage, playing crucial a role in erythrocyte hemolysis, exacerbating ineffective erythropoiesis and decreasing the lifespan of red blood cells (RBC). Catalase, glutathione peroxidase and peroxiredoxins act together to protect RBCs from hydrogen peroxide insult. Among them, peroxiredoxins stand out for their overall abundance and reactivity. In RBCs, Prdx2 is the third most abundant protein, although Prdxs 1 and 6 isoforms are also found in lower amounts. Despite the importance of these enzymes, Prdx1 and Prdx2 may have their peroxidase activity inactivated by hyperoxidation at high hydroperoxide concentrations, which also promotes the molecular chaperone activity of these proteins. Some studies have demonstrated the importance of Prdx1 and Prdx2 for the development and maintenance of erythrocytes in hemolytic anemia. Now, we performed a global analysis comparatively evaluating the expression profile of several antioxidant enzymes and their physiological reducing agents in patients with beta thalassemia intermedia (BTI) and healthy individuals. Furthermore, increased levels of ROS were observed not only in RBC, but also in neutrophils and mononuclear cells of BTI patients. The level of transcripts and the protein content of Prx1 were increased in reticulocyte and RBCs of BTI patients and the protein content was also found to be higher when compared to beta thalassemia major (BTM), suggesting that this peroxidase could cooperate with Prx2 in the removal of H2O2. Furthermore, Prdx2 production is highly increased in RBCs of BTM patients that present high amounts of hyperoxidized species. A significant increase in the content of Trx1, Srx1 and Sod1 in RBCs of BTI patients suggested protective roles for these enzymes in BTI patients. Finally, the upregulation of Nrf2 and Keap1 transcription factors found in BTI patients may be involved in the regulation of the antioxidant enzymes analyzed in this work.

Global gene expression reveals an increase of HMGB1 and APEX1 proteins and their involvement in oxidative stress, apoptosis and inflammation pathways among beta‐thalassaemia intermedia and major phenotypes

“…When bound to PRDX1, APEX1 remains in the cytoplasm, whereas in its unbound state it is located in the nucleus. Previous reports from our group revealed a decrease in the production of PRDX1 in BTM when compared with BTI patients (Romanello et al, 2018). These results suggest a relocation of APEX1 to the nucleus during the differentiation of BTM cells, which was expelled near the end of differentiation.…”

“…Several recent reports show that regulation of oxidative stress and generation of ROS plays a critical role in the severity of BT, and are directly involved in aging, apoptosis and inflammation of cells (Voskou et al , ; Hirsch et al , ; Romanello et al , ). We therefore evaluated the DEGs that were involved in these pathways; two genes ( APEX1 and HMGB1 ) were identified that showed a strict correlation with other important key proteins involved in these biological processes.…”

Proteome of Stored RBC Membrane and Vesicles from Heterozygous Beta Thalassemia Donors

“…The potentially toxic unstable free α-globin chains in βThal + RBCs can be eliminated by functionally interconnected protein quality control pathways [ 26 ]. It has been suggested that chaperones may be involved in α-globin refolding or targeting for degradation to proteasome [ 12 , 27 , 28 , 29 ], and, consequently, numerous molecular chaperones are upregulated in βThal + trait erythroblasts in mice.…”

Epigenetic Insights and Potential Modifiers as Therapeutic Targets in β–Thalassemia

“…NRF2 interacts with KEAP1 to form the NRF2/ KEAP1 complex in response to oxidative stress during erythrocyte development; KEAP1 oxidation allows NRF2 release turn, up-regulates PRDX1 and SOD1 production. In a Brazilian cohort, increased levels of the NRF2/KEAP1 complex were observed in β –thalassemia intermedia (n = 15) patients where the expression of NRF2 was more prominent (approximately a 3-fold change) than KEAP1 (approximately a 2-fold change), supporting the critical role of NRF2 in compensating for oxidative stress [ 65 ].…”

“…PRDX1 gene expression and protein levels were found to be elevated in the reticulocytes and erythrocytes of β –thalassemia intermedia patients (n = 15) compared with healthy individuals (n = 16). In β –thalassemia major patients (n = 8), however, the up-regulation of PRDX1 was limited to gene expression, suggesting that high ROS levels in β –thalassemia major patients degrade PRDX1 transcripts, hindering protein production [ 65 ].…”