PhD candidate Penn State University State College, Pennsylvania, United States
Disclosure(s):
Sara Trimidal: No financial relationships to disclose
Introduction/Rationale: During Anemia of Inflammation (AI), pro-inflammatory cytokines skew hematopoiesis towards myelopoiesis and impair homeostatic steady-state erythropoiesis, thus decreasing overall erythroid output. These same signals promote stress erythropoiesis (SE), a compensatory pathway that produces a bolus of erythrocytes through rapid proliferation of stress erythroid progenitors (SEPs) and differentiation to mature erythrocytes. We identified nitric oxide (NO) as a signal that rewires metabolism to promote SEP proliferation while also inhibiting differentiation. NO drives the formation of multi-enzyme condensates called purinosomes that allow for efficient metabolic channeling of intermediates of de novo purine biosynthesis.
Methods: Murine (C57BL/6) bone marrow cells were isolated and grown in specialized media that mimic the proliferation stage of SE. Cultures were treated with 1400W, a nitric oxide synthase (NOS2) inhibitor, or vehicle control. To investigate purinosome formation and activity, we utilized a flow cytometry-based proximity ligation assay and isotope tracing.
Results: Treatment with 1400W decreased SEP proliferation, purinosome formation, and purine levels compared to wild-type (WT) control. Moreover, glutamine, a key metabolite in NO production, is utilized in WT SEPs to form purines and pyrimidines. We predict incorporation of glutamine in nucleotides will decrease with 1400W treatment, and ongoing studies will investigate such changes. Results will then be compared to Nos2 KO SEPs.
Conclusion: The role of NO is implicated in sickle cell disease, where patients exhibit SE but limited NO availability, which could be the cause of anemia. Additionally, SE is effective in responding to acute inflammatory insults, but the SE response to chronic inflammation is impaired leading to AI. Understanding how SEPs are metabolically regulated to support their proliferation and maturation into erythrocytes during inflammatory stress would allow us to identify new targets for therapies for AI.
