Ancient genomic linkage of alpha-globin and Nprl3 couples metabolism with erythropoiesis

Development of red blood cells from progenitors requires profound reshaping of both gene expression and metabolism. How these processes are coupled is unclear. Nprl3, an inhibitor of mTORC1, has remained in synteny with the -globin genes for >500 million years, and harbours most of the -globin enhancers. However, whether Nprl3 itself serves an erythroid role is unknown. While hematopoietic progenitors rely on tonic expression of baseline Nprl3, erythroblasts experience ‘boosted’ Nprl3 expression. Using Nprl3-deficient fetal liver and adult competitive bone marrow - fetal liver chimaeras, we show that NprI3 is required for sufficient erythropoiesis. Loss of Nprl3 elevates mTORC1 signalling, suppresses autophagy and disrupts erythroblast glycolysis. Human NPRL3-knockout erythroid progenitors produce fewer enucleated cells and demonstrate dysregulated mTORC1 signalling in response to nutrient availability and erythropoietin. Thus, Nprl3 is a key regulator of erythroid metabolism. Finally, we show that the alpha-globin enhancers upregulate erythoid NprI3 expression, and that this activity supports optimal erythropoiesis.