Session: 101. Red Cells and Erythropoiesis, Structure and Function, Metabolism, and Survival, Excluding Iron: Poster III
Hematology Disease Topics & Pathways:
red blood cells, Biological Processes, erythropoiesis, metabolomics
Methods: Four models of erythropoiesis were used in this study. 1) Mice were treated with phenylhydrazine (Phz) to induce acute hemolysis followed by erythropoietic recovery, leading to an increase in circulating reticulocytes. 2) Mice were lethally irradiated and transplanted with wild-type or sickle cell bone marrow, leading to anemic profiles in sickle cell chimeras. 3) The mouse erythroleukemic (MEL) cell line was treated with DMSO to induce differentiation. 4) The human erythroleukemic (K562) cell line was treated with sodium butyrate to induce differentiation. For the in vivo mouse models, blood was collected from control and treated animals, and complete blood count (CBC) analysis was performed. For the in vitro cell culture models, the mRNA levels of β-globin were measured by Q-RT-PCR in control and differentiated cells, and the degree of hemoglobinization was determined visually and via staining for heme. In addition, metabolites were extracted from the collected RBCs and erythroleukemic cell lines, and a Snapshot LC/MS metabolomic platform was used to identify commonly altered metabolites.
Results: We first validated our four models of erythropoiesis. Treatment with Phz decreased the number of total RBCs while increasing the RBC distribution width, indicating an increased number of reticulocytes (more immature RBCs) in circulation. Similar results were seen in the sickle cell chimeras. Treatment of MEL and K562 cells with DMSO and sodium butyrate, respectively, resulted in increased expression of β-globin, increased levels of heme, and increased red color. Then, using our Snapshot metabolomic platform, we identified global changes in RBC metabolism during erythropoiesis. Analyses of the commonly altered metabolites in the in vitro and in vivo models revealed an increase in amino acid, mitochondrial, and urea cycle metabolism during erythropoiesis. L-aspartate levels were particularly upregulated, especially in DMSO-treated MEL cells. We are now investigating the role of aspartate in the regulation of erythropoiesis.
Conclusions: We defined how the metabolome was altered in multiple in vitro and in vivo models of erythropoiesis and identified global changes in RBC metabolism between the different models. Specifically, we found that L-aspartate was upregulated during RBC differentiation in all four models. Aspartate is an amino acid that plays a role in many processes in cells, including nucleotide biosynthesis, redox homeostasis, and amino acid biosynthesis. We hypothesize that aspartate metabolism is critical for RBC differentiation and that its dysregulation exacerbates disease of ineffective erythropoiesis, such as sickle cell anemia and β-thalassemia. We are currently testing its role in inducing hemoglobinization and in regulating the commitment of erythroid progenitor cells to an irreversible loss of proliferation. Overall, we believe that understanding the precise mechanisms by which cellular metabolism plays a role in proper RBC differentiation may lead to better therapies for diseases of ineffective erythropoiesis, such as sickle cell anemia and thalassemia.
Disclosures: No relevant conflicts of interest to declare.