E-MTAB-8611
Dual role of EZH2 on megakaryocyte differentiation, ChIP-seq analysis at different stages of megakaryocyte maturation
EZH2, the enzymatic component of PRC2, has been identified as a key factor in hematopoiesis. EZH2 loss of function mutations have been found in myeloproliferative neoplasms, more particularly in myelofibrosis, but the precise function of EZH2 in megakaryopoiesis is not fully delineated. Here, we show that EZH2 inhibition by small molecules and shRNA induces MK commitment by accelerating lineage marker acquisition without change in proliferation. Later in differentiation, EZH2 inhibition blocks proliferation and endomitosis and decreases proplatelet formation. EZH2 inhibitors similarly reduce polyploidization and proplatelet formation of JAK2V617F MK. In transcriptome profiling, the defect in proplatelet formation was associated with an aberrant actin cytoskeleton regulation pathway, whereas polyploidization was associated with an inhibition of expression for a set of genes involved in DNA replication and repair, and an upregulation of CDK inhibitors, more particularly CDKN1A and CDKN2D. The knockdown of CDKN1A and/or CDKN2D could partially rescue the percentage of polyploid MKs. However only CDKN1A was regulated by H3K27me3 suggesting that EZH2 controls MK polyploidization through a direct regulation of CDKN1A and indirectly of CDKN2D.
EZH2, the enzymatic component of PRC2, has been identified as a key factor in hematopoiesis. EZH2 loss of function mutations have been found in myeloproliferative neoplasms, more particularly in myelofibrosis, but the precise function of EZH2 in megakaryopoiesis is not fully delineated. Here, we show that EZH2 inhibition by small molecules and shRNA induces MK commitment by accelerating lineage marker acquisition without change in proliferation. Later in differentiation, EZH2 inhibition blocks proliferation and endomitosis and decreases proplatelet formation. EZH2 inhibitors similarly reduce polyploidization and proplatelet formation of JAK2V617F MK. In transcriptome profiling, the defect in proplatelet formation was associated with an aberrant actin cytoskeleton regulation pathway, whereas polyploidization was associated with an inhibition of expression for a set of genes involved in DNA replication and repair, and an upregulation of CDK inhibitors, more particularly CDKN1A and CDKN2D. The knockdown of CDKN1A and/or CDKN2D could partially rescue the percentage of polyploid MKs. However only CDKN1A was regulated by H3K27me3 suggesting that EZH2 controls MK polyploidization through a direct regulation of CDKN1A and indirectly of CDKN2D.