The transcriptional and regulatory identity of erythropoietin producing cells

Erythropoietin (Epo) is the master regulator of erythropoiesis and oxygen homeostasis. Despite its physiological importance, the molecular and genomic contexts of the cells responsible for renal Epo production have not yet been resolved, limiting effective cell-based therapies for anemia. Here, we performed single-cell profiling of an Epo reporter mouse to molecularly identify Epo-producing cells under hypoxic conditions. We report that a distinct and homogeneous population of kidney stromal cells, which we name Norn cells, are the sole source of Epo production in vivo. Extensive characterization of the Norn epigenetic and transcriptional landscapes revealed Norn-specific markers, pathways, and transcription factor circuits conserved from mice to humans. These findings open new avenues to functionally dissect EPO gene regulation in human evolution and disease, and pave the way for the next generation of genetic and cell-based approaches for EPO therapies. Overall design: Wild type C57BL/6 and Epo-tdTomato reporter mice were subjected to hypoxic conditions for 4 hours to extract renal cells responsible for Epo expression and secretion. Epo-CreERT2-tdTomato were first subjected to Epo-tdTomato induction by 5 consecutive gavages of tamoxifen. Different gating scheme were used to enrich for Epo-producing Norn cells. Non-tumour kidney samples were obtained from partial or radical nephrectomies with renal cell carcinoma indication under the Helsinki protocols 6370-19-SMC (Sheba-Telhashomer medical center), 0417-20-TLV (Ichilov hospital), and 0297-22-HMO (Hadassah medical center) with local IRB approval from Weizmann Institute of Science (1568-1).