Abstract AML1-ETO (AE) is a fusion transcription factor, generated by the t(8;21) translocation, that functions as a leukemia promoting oncogene. Here, we demonstrate that TATA-Box Binding Protein Associated Factor 1 (TAF1) associates with K43 acetylated AE and this association plays a pivotal role in the proliferation of AE-expressing acute myeloid leukemia (AML) cells. ChIP-sequencing indicates significant overlap of the TAF1 and AE binding sites. Knockdown of TAF1 alters the association of AE with chromatin, affecting of the expression of genes that are activated or repressed by AE. Furthermore, TAF1 is required for leukemic cell self-renewal and its reduction promotes the differentiation and apoptosis of AE+ AML cells, thereby impairing AE driven leukemogenesis. Together, our findings reveal a role of TAF1 in leukemogenesis and identify TAF1 as a potential therapeutic target for AE-expressing leukemia.
The multipotent and easily accessible characteristics of dental pulp stem cells (DPSCs) make them a promising target for bone tissue engineering. Long non‑coding RNAs (lncRNAs) have an important role in the osteogenic differentiation of mesenchymal stem cells. Nevertheless, whether lncRNAs are involved in the osteogenic differentiation of DPSCs remains unclear. The present study examined the expression alterations of lncRNAs in tumor necrosis factor‑α induced osteogenic differentiation of DPSCs. Following identification of differentially expressed lncRNAs at different time points by reverse transcription‑quantitative polymerase chain reaction, profiling analysis was performed and a profile was further validated, in which lncRNA expression levels demonstrated significant upregulation. The next generation sequencing analysis identified 77 (58 upregulated and 19 downregulated) and 133 differentially expressed lncRNAs (73 upregulated and 60 downregulated) at 7 and 14 days post‑treatment, respectively. In addition, 34 lncRNAs were predicted to be strongly associated with 336 mRNA transcripts that underwent significant alterations during osteogenic differentiation. The present data demonstrated that one lncRNA, X inactive specific transcript, is essential for efficient osteogenic differentiation of DPSCs by alkaline phosphatase staining. In summary, the present findings provide insight for the understanding of how non‑coding RNAs are involved in regulating the osteogenic differentiation of DPSCs, which may further advance the translational studies of bone tissue engineering.
Abstract Chromatin modifying enzymes, and specifically the protein arginine methyltransferases (PRMTs) have emerged as important targets in cancer. PRMT4, also known as CARM1, is overexpressed in a number of cancers, including breast, prostate, pancreatic, and lung cancer. Our lab reported the overexpression of PRMT4 in the context of acute myeloid leukemia (AML), showing that more than 70% of cytogenetically normal AML patients have up-regulation of PRMT4. Here, we investigated the role of PRMT4 in normal hematopoiesis and leukemia development. In order to study the role of PRMT4 in normal hematopoiesis, Prmt4-floxed mice were crossed with Vav1-cre mice purchased from the Jackson Laboratory. Inducible Prmt4 conditional KO mice were generated by crossing Prmt4-floxed mice with Mx1-Cre mice and Prmt4 gene excision was induced by poly(I:C). Using this hematopoietic specific knockout system, we show that loss of PRMT4 has little effect on normal hematopoiesis, but promotes the differentiation of hematopoietic stem and progenitor cells. Next we evaluated the role of PRMT4 in leukemia development using leukemia transplantation models driven by fusion oncoproteins. Strikingly, the knockout of PRMT4 completely abrogates leukemia initiation in fetal liver transplantation models driven by the AML1-ETO or MLL-AF9 fusion proteins. We further characterized the mechanism for the leukemia-specific dependence on PRMT4 using leukemia cell lines and found that knockdown of PRMT4 impairs cell cycle progression, decreases proliferation, and induces rapid apoptosis. To examine PRMT4 dependent changes in gene expression in a leukemia system, we used lentiviral vectors that express RFP and shRNAs directed against PRMT4. We knocked down PRMT4 in four leukemia cell lines or normal human cord-blood derived CD34+ cells. Gene set enrichment analysis showed that all four leukemia cell lines with knockdown of PRMT4 significantly down-regulated E2F target genes compared to the scrambled control. Chromatin immunoprecipitation analysis (ChIP) confirmed the presence of PRMT4 and H3R17 dimethylation at the promoter regions of E2F1 targets. The PRMT4 conditional knockout mice and PRMT4 knockdown experiments both suggest that the loss of PRMT4 protein has a selective effect on leukemia cells compared to normal hematopoietic stem and progenitor cells. Collectively, this work suggests that targeting PRMT4 through chemical inhibition may be an effective therapeutic strategy for AML and other cancers with up-regulation of PRMT4. Citation Format: Sarah M. Greenblatt, Pierre-Jacques J. Hamard, Takashi Asai, Na Man, Concepcion Martinez-Caja, Fan Liu, Stephen Nimer. Identification of CARM1/PRMT4 as a novel therapeutic target for AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3340. doi:10.1158/1538-7445.AM2017-3340
Abstract The cationic surfactant, N-(3-octadecylamino-2-hydroxyl) propyl trimethyl ammonium chloride was synthesized by an improved synthesis method and the structure was confirmed by Mass Spectrometry and 1 H NMR Spectrometry. The physiochemical properties of the product were investigated systematically by surface tension and conductivity measurements. Various physiochemical parameters were calculated to evaluate the surface activities of the surfactant. The results show that both the critical micelle concentration and the degree of counterion dissociation increased with increasing temperature, but the surface tension at CMC decreased, which is opposite to that obtained on the previous condition with increasing NaCl concentration. The thermodynamic parameters obtained from conductivity measurement show that the micelle formation of the surfactant is entropy-driven in the investigated temperature range. While used as an asphalt emulsifier, N-(3-octadecylamino-2-hydroxyl) propyl trimethyl ammonium chloride exhibited an excellent emulsifying ability and it was a medium-set asphalt emulsifier.
Epigenetic regulators play critical roles in normal hematopoiesis, and the activity of these enzymes is frequently altered in hematopoietic cancers. The major type II protein arginine methyltransferase PRMT5 catalyzes the formation of symmetric dimethyl arginine and has been implicated in various cellular processes, including pluripotency and tumorigenesis. Here, we generated Prmt5 conditional KO mice to evaluate the contribution of PRMT5 to adult hematopoiesis. Loss of PRMT5 triggered an initial but transient expansion of hematopoietic stem cells (HSCs); however, Prmt5 deletion resulted in a concurrent loss of hematopoietic progenitor cells (HPCs), leading to fatal BM aplasia. PRMT5-specific effects on hematopoiesis were cell intrinsic and depended on PRMT5 methyltransferase activity. We found that PRMT5-deficient hematopoietic stem and progenitor cells exhibited severely impaired cytokine signaling as well as upregulation of p53 and expression of its downstream targets. Together, our results demonstrate that PRMT5 plays distinct roles in the behavior of HSCs compared with HPCs and is essential for the maintenance of adult hematopoietic cells.
Protein arginine methyltransferase 5 (PRMT5) is overexpressed in many cancer types and is a promising therapeutic target for several of them, including leukemia and lymphoma. However, we and others have reported that PRMT5 is essential for normal physiology. This dependence may become dose limiting in a therapeutic setting, warranting the search for combinatorial approaches. Here, we report that PRMT5 depletion or inhibition impairs homologous recombination (HR) DNA repair, leading to DNA-damage accumulation, p53 activation, cell-cycle arrest, and cell death. PRMT5 symmetrically dimethylates histone and non-histone substrates, including several components of the RNA splicing machinery. We find that PRMT5 depletion or inhibition induces aberrant splicing of the multifunctional histone-modifying and DNA-repair factor TIP60/KAT5, which selectively affects its lysine acetyltransferase activity and leads to impaired HR. As HR deficiency sensitizes cells to PARP inhibitors, we demonstrate here that PRMT5 and PARP inhibitors have synergistic effects on acute myeloid leukemia cells.
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