Genetic architecture of the murine red blood cell proteome reveals central role of hemoglobin beta cysteine 93 in maintaining redox balance.

Red blood cells (RBCs) transport oxygen but accumulate oxidative damage over time, reducing function in vivo and during storage, critical for transfusions. To explore the genetics of RBC resilience, we profiled proteins, metabolites, and lipids from fresh and stored RBCs from 350 genetically diverse mice. Our analysis identified over 6,000 quantitative trait loci (QTLs). Compared to other tissues, the prevalence of trans genetic effects over cis ones reflects the absence of de novo protein synthesis in anucleated RBCs. QTL hotspots at Hbb, Hba, Mon1a, and (storage-specific) Steap3 linked ferroptosis to hemolysis. Proteasome QTLs clustered at multiple loci, underscoring the importance of degrading oxidized proteins. Post-translational modification (PTM) QTLs mapped predominantly to hemoglobins, including cysteine residues. The loss of reactive C93 in humanized mice (hemoglobulin beta [HBB] C93A) disrupted redox balance, glutathione pools, glutathionylation, and redox PTMs. These findings highlight genetic regulation of RBC oxidation, with implications for transfusion biology and oxidative-stress-dependent hemolytic disorders.