Histone methyltransferase NSD3 orchestrates early erythropoiesis by regulating erythroid progenitor cell...

Histone methyltransferase NSD3 also known KMT3F, is an epigenetic regulator that methylates histone H3 at lysine 36, a mark associated with gene activation. Functionally, NSD3 is crucial for supporting various cellular and developmental processes, and its deregulation can lead to various disease conditions, including solid and hematological cancers. However, the role of NSD3 in regulating normal hematopoiesis remains elusive. In the present study, we have investigated the role of NSD3 in regulating human erythropoiesis, the process of red blood cell production from hematopoietic stem cells (HSCs). To achieve this, we isolated CD34⁺ HSCs from a healthy donor and subjected them to ex-vivo erythroid differentiation. Using a combination of lentiviral transduction and small hairpin RNA-mediated knockdown approaches, we targeted NSD3 depletion during the early phases of erythroid differentiation. Our results demonstrated that depleting NSD3 on days 2 and 7 of ex-vivo erythroid differentiation resulted in notable disruptions of erythropoiesis process. Specifically, NSD3 downregulation resulted in a decreased megakaryocyte-erythroid progenitors, reduced colony formation, and a significant decrease in erythroid differentiation markers. Furthermore, NSD3 depletion altered erythroid differentiation by favouring basophilic erythroblasts over ortho/polychromatic erythrocytes. At the transcriptomic level, NSD3 depletion led to the downregulation of key hematopoiesis-specific transcription factors and genes associated with erythroid differentiation and hemoglobin synthesis. Additionally, NSD3 depletion also induced apoptosis and hindered cell proliferation, accompanied by altered expression of genes involved in these pathways. Our findings uncover a previously undescribed role of histone methyltransferase NSD3 in regulating human erythropoiesis.