Role of CYB5R3 in erythropoiesis

About This Grant

Grant title: Role of CYB5R3 in erythropoiesis Funding mechanism: NIH/NHLBI-F32 PROJECT SUMMARY/ABSTRACT Cytochrome b5 reductase 3 (CYB5R3) plays a critical role in regulating redox signaling in both physiological and pathological contexts. Key biological substrates of CYB5R3 include hemoproteins such as hemoglobin, myoglobin, and soluble guanylate cyclase (sGC), as well as vitamin E and coenzyme Q. Our recent findings demonstrate that the CYB5R3 T117S variant, which results in approximately 50% loss of reductase activity, serves as a modifier of hydroxyurea-induced fetal hemoglobin (HbF) production—a widely used therapeutic approach for managing anemia in sickle cell disease (SCD). Using CYB5R3 knockout CD34+ hematopoietic stem cells (HSC)s, we found depleted baseline hemoglobin and impaired hydroxyurea- induced HbF production and erythroid maturation. In CYB5R3-deleted human erythroleukemic K562 cells, we similarly found depleted baseline hemoglobin, but in the presence of heme deficiency. The role of CYB5R3 in erythropoiesis remains unexplored despite. Based on our preliminary and published data, we hypothesize that CYB5R3 plays a previously unrecognized role in erythropoiesis by regulating heme biosynthesis. This hypothesis will be tested using two specific aims: Aim 1 will investigate the impact of CYB5R3 depletion on hemoglobin synthesis and erythropoiesis using human K562 cells. Aim 2 will employ a novel mouse model with hematopoietic compartment-specific deletion of CYB5R3 to assess its effects on erythropoiesis in vivo, both under baseline conditions and following hypoxic conditions. Successful completion of this study will provide novel insights into the significance of CYB5R3 in erythropoiesis, with potential applications in drug development, regenerative medicine, and the improved management of genetic anemias. Moreover, this research—plan combined with mentored training under Drs. Straub and Wood, interdisciplinary collaborations, and a structured career development plan within the outstanding training environment at the University of Pittsburgh School of Medicine—will equip the applicant with the expertise necessary to achieve a long-term career in biomedical research.