Li, Y.; Yang, Y.; Hu, B.; Wang, Z.; Wang, W.; He, X.; Wu, X.; Lin, S.; Mohandas, N.; Liu, H.; Gong, J.; Liang, L.; Liu, J.

Erythropoiesis is precisely regulated by multilayer networks and is crucial for maintaining steady-state hemoglobin levels and ensuring effective oxygen transport. Alternative polyadenylation (APA) is a post-transcriptional regulatory mechanism that generates multiple mRNA isoforms from a single gene, based on specific 3\'-untranslated region sequences. While APA plays a vital role in various cellular processes, its mechanism in erythropoiesis remains unexplored. Here, we employed an integrative approach combining bioinformatics and experimental validation to systematically analyze APA\'s role in erythropoiesis. We mapped the APA landscape during erythroid differentiation, discovering notable APA shifts crucial for the maturation from burst-forming unit erythroid to colony-forming unit erythroid. Notably, our findings highlighted PABPC1 as the primary APA regulator of these stages. Functional investigations revealed that knocking down PABPC1 disrupts erythroid progenitor cell proliferation and differentiation, implicating the protein\'s essential role in modulating cell fate through APA regulation. We further identified that decreased PABPC1 levels led to the increased usage of the proximal polyA site of TSC22D1 and gene overexpression, revealing a novel mechanism through which APA affects erythroid progenitor expansion and differentiation. These insights uncover a novel dimension of APA regulation in early erythropoiesis, providing new strategies for the treatment of diseases associated with erythropoiesis disorders.