Project description:Loss of function TET2 mutations are frequently seen in myelodysplastic syndrome (MDS) patients. Previous studies have demonstrated that TET2 deficiency enhances maintenance of MDS hematopoietic stem and progenitor cells (HSPCs). Nonetheless, the pathogenic role of TET2 in MDS progression remains elusive. Here, we demonstrate Tet2 knockout (KO) markedly accelerated malignant transformation in Nup98-HoxD13 (NHD13) transgenic mice and promotes leukemogenesis of HoxA9 transduction/transplant mice. Consistently, low TET2 level cooperating with high HOXA9 level predicts poor outcome of MDS patients. Notably, Tet2 KO conferred a clonal advantage to the HSPCs of NHD13 mice. Whole-exome sequencing revealed that Tet2 KO facilitates accumulation of mutations at genes associated with leukemogenesis, including Arih2, whose loss of function promotes MDS cells proliferation. Using 5-hydroxymethylcytosine immunoprecipitation coupled with high-throughput sequencing analysis, we found while Tet2 deletion decreased overall 5hmC levels, it also increased 5hmC distribution at certain mutation loci such as Arih2. Vitamin C treatment, which mimics Tet2/Tet3 restoration, blocked disease progression in Tet2-deficient NHD13 mice. Collectively, our findings demonstrate that TET2 activity governs occurrence of secondary mutations in MDS HSPCs, providing a rationale for enhancing TETs function to block MDS-malignant transformation.
Project description:Loss of function TET2 mutations are frequently seen in myelodysplastic syndrome (MDS) patients. Previous studies have demonstrated that TET2 deficiency enhances maintenance of MDS hematopoietic stem and progenitor cells (HSPCs). Nonetheless, the pathogenic role of TET2 in MDS progression remains elusive. Here, we demonstrate Tet2 knockout (KO) markedly accelerated malignant transformation in Nup98-HoxD13 (NHD13) transgenic mice and promotes leukemogenesis of HoxA9 transduction/transplant mice. Consistently, low TET2 level cooperating with high HOXA9 level predicts poor outcome of MDS patients. Notably, Tet2 KO conferred a clonal advantage to the HSPCs of NHD13 mice. Whole-exome sequencing revealed that Tet2 KO facilitates accumulation of mutations at genes associated with leukemogenesis, including Arih2, whose loss of function promotes MDS cells proliferation. Using 5-hydroxymethylcytosine immunoprecipitation coupled with high-throughput sequencing analysis, we found while Tet2 deletion decreased overall 5hmC levels, it also increased 5hmC distribution at certain mutation loci such as Arih2. Vitamin C treatment, which mimics Tet2/Tet3 restoration, blocked disease progression in Tet2-deficient NHD13 mice. Collectively, our findings demonstrate that TET2 activity governs occurrence of secondary mutations in MDS HSPCs, providing a rationale for enhancing TETs function to block MDS-malignant transformation.
Project description:Setd2, the histone H3 lysine 36 methyltransferase, plays an important role in the pathogenesis of hematologic malignancies. The research on the role of Setd2 in leukemogenesis has made great progress, but its role in MDS is still unknown. Here, we knock out Setd2 in the NUP98-HOXD13 transgenic (NHD13 Tg) mouse, and demonstrate that loss of Setd2 accelerates the transformation of MDS into AML. The conditional deletion of Setd2 also interferes the differentiation of hematopoietic stem and progenitor cells (HSPCs), and results in the decrease of granulocyte monocyte progenitor (GMP) cells, increase of megakaryocyte erythroid progenitor (MEP) cells and common myeloid progenitor (CMP) cells. Loss of Setd2 impairs erythroid differentiation, includes cell cycle arrest in G2-M and enhances the selt-renewal ability of HSPCS. Our RNA-seq,ChIP-seq and WGBS analysis indicats that S100A8 and S100A9 are direct target genes of H3K36me3 and expression of heterodimeric S100 calcium-binding proteins S100A8 and S100A9 are downregulated in HSPCs when Setd2 deficiency. Addition of recombinant S100A8 or S100A9 weakens the clonogenic progenitors of Setd2 deficient HSPCs. Therefore, our results demonstrate that loss of Setd2 promotes the transformation of MDS into AML, which proves Setd2 as a tumor suppressor in MDS, and provides a potential therapeutic target for MDS associated leukemia.
Project description:Improved understanding of mechanisms regulating myelodysplastic syndrome (MDS) hematopoietic stem/progenitor cell (HSPC) growth and self-renewal is critical for developing MDS therapy. We revealed a novel regulatory axis that SIRT1-deficiency induced TET2 hyperacetylation promotes MDS HSPC functions, and provide an approach to target MDS HSPCs by activating SIRT1 deacetylase.
Project description:To investigate the signaling pathway required for the Tet2 mutant associated clonal hematopoiesis, we identified the activated signaling pathway in Tet2-deficient hematopoietic stem/progenitor cells compared to WT cells and using transgentic mouse model to validate our findings. In short, the cGAS-STING pathway is activated in Tet2-deficient HSPCs and promotes the development of CH associated with Tet2 deficiency.