Alternative polyadenylation links RNA processing to iron metabolism in human erythropoiesis.

Erythropoiesis requires precise coordination of transcriptional and co-/post-transcriptional programs, yet the role of alternative polyadenylation (APA) in this process remains poorly understood. Here, we profiled the genome-wide dynamic APA landscape during erythropoiesis using single-cell RNA sequencing (scRNA-seq). Through clustering and functional enrichment analysis, seven distinct APA dynamic patterns were identified, with genes showing stage-specific APA changes enriched in erythroid lineage differentiation, heme synthesis, and iron metabolism. Combining motif analysis near polyadenylation sites (PASs) and APA regulators expression profiling, we observed that cleavage and polyadenylation specificity factor 6 (CPSF6), a critical APA regulator, exhibited significant variation. Functional assays demonstrated that CPSF6 facilitates erythropoiesis, as its depletion impaired heme synthesis and intracellular iron deficiency. Mechanistically, CPSF6 depletion shortened the 3'UTR length of iron metabolism regulators (FAM210B, IREB2, TFRC), which was accompanied by reduced expression of these genes. Clinically, CPSF6 and these APA-regulated iron metabolism-related genes were aberrantly upregulated in polycythemia vera (PV) patients, correlating with erythroid hyperproliferation. Collectively, our findings support a CPSF6-APA-iron homeostasis axis as an important co-/post- transcriptional regulatory mechanism in erythropoiesis, and implicate its dysregulation in the pathogenesis of PV, offering novel molecular targets for therapeutic intervention in myeloproliferative neoplasms.