Project description:The EZH2 histone methyltransferase is required for B cells to form germinal centers (GCs). Here we show that EZH2 mediates GC formation through repression of cyclin-dependent kinase inhibitor CDKN1A (p21Cip1). Deletion of Cdkn1a rescued the GC reaction in Ezh2 knockout mice. To study the effects of EZH2 in primary GC B cells we generated and validated a 3D B cell follicular organoid system that mimics the endogenous GC reaction. Using this system we found that depletion of EZH2 suppressed G1 to S phase transition of GC B cells in a Cdkn1a dependent manner. GC B cells of Cdkn1a;Ezh2 double knockout mice exhibited high levels of phospho Rb, indicating that loss of Cdkn1a allows progression of cell cycle. Moreover, we show that the transcription factor E2F1 plays a major role in inducing EZH2 upregulation during the GC reaction. E2F1 deficient mice manifest impaired GC responses, which was rescued by restoring EZH2 expression, thus defining a positive feedback loop whereby EZH2 controls GC B cell proliferation by suppressing CDKN1A, allowing cell cycle progression with a concomitant phosphorylation of Rb and release of E2F1.
Project description:The EZH2 histone methyltransferase is highly expressed in germinal center (GC) B-cells and targeted by somatic mutations in B-cell lymphomas. Here we find that EZH2 deletion or pharmacologic inhibition suppresses GC formation and functions in mice. EZH2 represses proliferation checkpoint genes and helps establish bivalent chromatin domains at key regulatory loci to transiently suppress GC B-cell differentiation. Somatic mutations reinforce these physiological effects through enhanced silencing of EZH2 targets in B-cells, and in human B-cell lymphomas. Conditional expression of mutant EZH2 in mice induces GC hyperplasia and accelerated lymphomagenesis in cooperation with BCL2. GCB-type DLBCLs are mostly addicted to EZH2, regardless of mutation status, but not the more differentiated ABC-type DLBCLs, thus clarifying the therapeutic scope of EZH2 targeting. RNA sequencing and H3K27me3 ChIP sequencing of human DLBCL cell lines and murine BCL1 cell line. RNA sequencing, H3K27me3 and H3K4me3 ChIP sequencing of B cells from de-identified human tonsills.
Project description:The EZH2 histone methyltransferase is highly expressed in germinal center (GC) B-cells and targeted by somatic mutations in B-cell lymphomas. Here we find that EZH2 deletion or pharmacologic inhibition suppresses GC formation and functions in mice. EZH2 represses proliferation checkpoint genes and helps establish bivalent chromatin domains at key regulatory loci to transiently suppress GC B-cell differentiation. Somatic mutations reinforce these physiological effects through enhanced silencing of EZH2 targets in B-cells, and in human B-cell lymphomas. Conditional expression of mutant EZH2 in mice induces GC hyperplasia and accelerated lymphomagenesis in cooperation with BCL2. GCB-type DLBCLs are mostly addicted to EZH2, regardless of mutation status, but not the more differentiated ABC-type DLBCLs, thus clarifying the therapeutic scope of EZH2 targeting.
Project description:Our computational approach identified E2F1 as a potential collaborator of EZH2 in androgen-independent prostate cancer. This experiment is to designed to validate the crosstalking of E2F1 and EZH2 pathways. We showed that majority of the EZH2-induced genes in androgen-independent prostate tumor cells are in downstream of E2F1, providing insight into the EZH2-E2F1 collaborative regulatory pathway.
Project description:Rb and E2F are thought to play antagonistic roles in celll proliferation. However, this model is based mostly from in vitro cell culture systems. We used small intestines to test this model in vivo. We found that deletion of E2f1-3 in the small intestine of mice suppressed the ectopic expression of E2F targets and cell proliferation caused by Rb-deficiency. Surprisingly, E2f1-3 deletion failed to arrest the proliferation of intestinal cells containing an intact Rb gene, and instead led to E2F target derepression and apoptosis. Experiment Overall Design: Total RNA of crypts and villi from wild-type, Rb-/-, E2f1-/-, E2f2-/-, E2f3-/-, E2f1-/-, E2f2-/-, and E2f3-/- small intestines. Small intestines were harvested 7 days after mice were injected intraperitoneally with beta-napthoflavone.
Project description: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.
Project description: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.
Project description: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.
Project description:From castration resistant prostate cancer (CRPC) regulatory network, we found over 90% negative feedback loop went through E2F1. And we detected PC3 and DU145 cells with depletion of E2F1 through the invasion, migration, proliferation and apoptosis experiments. In order to identify which genes trigger these phenomenon and regulatory mechanism of E2F1 in CRPC, we performed the gene expression between the vector and under the knockdown of E2F1 in PC3 and DU145 cells by RNA sequencing (RNA-seq). To investigate differentially expressed genes (false discovery rate (FDR) <0.05, |log2 (Fold Change)| > 1) between vector control and shE2F1 of CRPC cells, we performed processing RNA-Seq data using the Basespace. Then we verified some common two cells’ differentially expressed genes through quantitative real-time PCR.