RNA-seq of HBBP1 suppression during HPCs erythroid differentiation

As relics emerged in endless evolution, pseudogenes lost their coding potential compared to their protein homologs and are long believed to be functionless and thus evolve under neutrality. However, evidence supporting their functionality is quickly accumulating in recent two decades. Herein, we uncovered the evolution history and the essential role of hemoglobin subunit beta pseudogene 1 (HBBP1), which situates in the middle of fetal (?) and adult globin (d/ß) genes, in human erythropoiesis. HBBP1 was born in the common ancestor of eutherian mammals and under functional constraint in human populations. Remove of HBBP1 in human embryonic stem cells completely blocked their differentiation to erythroid cells, while erythroid differentiation of hematopoietic stem/progenitor cells was also dramatically impaired after HBBP1 reduction, evidencing HBBP1 was required for human erythropoiesis. Mechanistically, HBBP1 RNA harbored a binding motif of heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1), competing for the binding of HNRNPA1 and thus stabilizing the key regulator of erythropoiesis, T-cell acute lymphocytic leukemia 1 (TAL1). Moreover, HBBP1 was remarkably increased in ß-thalassemia patients and partially required for their fetal hemoglobin elevation. Overall design: RNA-seq of day8 and day14 cells, respectively differentiated from cord blood derived CD34+ HPCs by EPO. There are three groups: ctrl, HBBP1 shRNA-1 and HBBP1 shRNA-2.