Single-cell landscape of alternative polyadenylation in human lymphoid hematopoiesis.

ABSTRACT

Alternative polyadenylation (APA) is an essential post-transcriptional process that produces mature mRNA isoforms by regulating the usage of polyadenylation sites (PASs). APA is involved in lymphocyte activation; however, its role throughout the entire differentiation trajectory remains elusive. Here, we analyzed single-cell 3'-end transcriptome data from healthy subjects to construct a dynamic-APA landscape from hematopoietic stem and progenitor cells (HSPCs) to terminally differentiated lymphocytes. This analysis covered 19973 cells of 12 clusters from five lineages (B cells, CD4+ T cells, CD8+ T cells, natural killer cells, and plasmacytoid dendritic cells). A total of 2364 genes exhibited differential 3'UTR PAS usage, and 3021 genes displayed differential intronic cleavage during lymphoid differentiation. We observed a global trend of 3'UTR shortening during lymphoid differentiation. Nevertheless, specific events of both 3'UTR shortening and lengthening were also identified within each cluster. The APA patterns delineated three differentiation stages HSPCs, precursor cells, and mature cells. Moreover, we demonstrated that the conversion of naïve T cells to memory T cells was accompanied by dynamic APA in transcription factor-encoding genes (TCF7 and NFATC2IP), immune function-related genes (BCL2, CD5, CD28, GOLT1B, and TMEM59), and protein ubiquitination-related genes (UBE2G1, YPEL5, and SUMO3). These findings expand our understanding of the underlying molecular mechanisms of APA and facilitate studies on the regulatory role of APA in lymphoid hematopoiesis.