DNA and histone modifications exhibit noticeable impacts on gene expression 1 . Being the most prevalent internal modification in mRNA, N 6 -Methyladenosine (m 6 A) mRNA modification emerges as an important post-transcriptional mechanism of gene regulation 2 - 4 and plays critical roles in various normal and pathological bioprocesses 5 - 12 . However, how m 6 A is precisely and dynamically deposited in the transcriptome remains elusive. Here we report that H3K36me3 histone modification, a marker for transcription elongation, globally guides m 6 A modification. We found that m 6 A modifications enrich in the vicinity of H3K36me3 peaks, and are reduced globally when cellular H3K36me3 is depleted. Mechanistically, H3K36me3 is recognized and bound directly by METTL14, a critical component of the m 6 A methyltransferase complex (MTC), which in turn facilitates the binding of the m 6 A MTC to adjacent RNA polymerase II, and thereby delivering the m 6 A MTC to actively transcribed nascent RNAs to deposit m 6 A co-transcriptionally. In mouse embryonic stem cells, phenocopying Mettl14 silencing, H3K36me3 depletion also induces m 6 A reduction transcriptome-wide and in pluripotency transcripts, resulting in increased cell stemness. Collectively, our studies reveal the critical roles of H3K36me3 and METTL14 in determining precise and dynamic m 6 A deposition in mRNA, and uncover another layer of gene expression regulation involving crosstalk between histone modification and RNA methylation.

SET domain containing 2 (Setd2), encoding a histone methyltransferase, is associated with many hematopoietic diseases when mutated. By generating a novel exon 6 conditional knockout mouse model, we describe an essential role of Setd2 in maintaining the adult hematopoietic stem cells. Loss of Setd2 results in leukopenia, anemia, and increased platelets accompanied by hypocellularity, erythroid dysplasia, and mild fibrosis in bone marrow. Setd2 knockout mice show significantly decreased hematopoietic stem and progenitor cells except for erythroid progenitors. Setd2 knockout hematopoietic stem cells fail to establish long-term bone marrow reconstitution after transplantation because of the loss of quiescence, increased apoptosis, and reduced multiple-lineage terminal differentiation potential. Bioinformatic analysis revealed that the hematopoietic stem cells exit from quiescence and commit to differentiation, which lead to hematopoietic stem cell exhaustion. Mechanistically, we attribute an important Setd2 function in murine adult hematopoietic stem cells to the inhibition of the Nsd1/2/3 transcriptional complex, which recruits super elongation complex and controls RNA polymerase II elongation on a subset of target genes, including Myc. Our results reveal a critical role of Setd2 in regulating quiescence and differentiation of hematopoietic stem cells through restricting the NSDs/SEC mediated RNA polymerase II elongation.

Myelodysplastic syndromes (MDS) are heterogeneous hematopoietic disorders that are incurable with conventional therapy. Their incidence is increasing with global population aging. Although many genetic, epigenetic, splicing, and metabolic aberrations have been identified in patients with MDS, their clinical features are quite similar. Here, we show that hypoxia-independent activation of hypoxia-inducible factor 1α (HIF1A) signaling is both necessary and sufficient to induce dysplastic and cytopenic MDS phenotypes. The HIF1A transcriptional signature is generally activated in MDS patient bone marrow stem/progenitors. Major MDS-associated mutations (, and ) activate the HIF1A signature. Although inducible activation of HIF1A signaling in hematopoietic cells is sufficient to induce MDS phenotypes, both genetic and chemical inhibition of HIF1A signaling rescues MDS phenotypes in a mouse model of MDS. These findings reveal HIF1A as a central pathobiologic mediator of MDS and as an effective therapeutic target for a broad spectrum of patients with MDS. We showed that dysregulation of HIF1A signaling could generate the clinically relevant diversity of MDS phenotypes by functioning as a signaling funnel for MDS driver mutations. This could resolve the disconnection between genotypes and phenotypes and provide a new clue as to how a variety of driver mutations cause common MDS phenotypes. .

ObjectiveTo systematically evaluate the efficacy and safety of Modified Tongxie Yaofang (M-TXYF) for the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D).MethodElectronic databases including PubMed, Springer Link, EMBASE, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature (CBM), Wanfang, and Chinese Scientific Journals Database (VIP) were conducted from their inception through May 11, 2017 without language restrictions. Primary and secondary outcomes were estimated by 95% confidence intervals (CI). RevMan 5.3 and the Cochrane Collaboration’s risk of bias tool were analyzed for this meta-analysis.ResultsTwenty-three literatures with a total of 1972 patients were included for the meta-analysis. The overall risk of bias evaluation was low. The pooled odds ratio showed that M-TXYF was significantly superior to routine pharmacotherapies (RP) in clinical therapeutic efficacy (OR 4.04, 95% CI 3.09, 5.27, P < 0.00001, therapeutic gain = 17.6%, number needed to treat (NNT) = 5.7). Moreover, compared with RP, M-TXYF showed that it can significantly reduce the scores of abdominal pain (standardized mean difference (SMD) -1.27; 95% CI -1.99, -0.56; P = 0.0005), abdominal distention (SMD -0.37; 95% CI -0.73, -0.01; P = 0.09), diarrhea (SMD -1.10; 95% CI -1.95, -0.25; P = 0.01), and frequency of defecation (SMD -1.42; 95% CI -2.19, -0.65; P = 0.0003). The differences of the adverse events between experiment and control groups had no statistical significance.ConclusionThis meta-analysis indicated that M-TXYF could be a promising Chinese herbal formula in treating IBS-D. However, considering the lack of higher quality of randomized controlled trials (RCTs), highly believable evidences should be required.

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BackgroundPARP-1 plays a critical role in DNA damage repair and contributes to progression of cancer. To explore the role of PARP-1 in acute myeloid leukemia (AML), we analyzed the expression of PARP-1 in AML and its relation to the clinical prognosis. Then, we investigated the efficacy and mechanism of PARP inhibitor BMN673 (Talazoparib) combined with NL101, a novel SAHA-bendamustine hybrid in vitro and in vivo.MethodsThe expression of PARP-1 in 339 cytogenetically normal AML (CN-AML) cases was evaluated using RT-PCR. According to the expression of PARP-1, the clinical characteristics and prognosis of the patients were grouped and compared. The combination effects of BMN673 and NL101 were studied in AML cells and B-NSG mice xenograft model of MV4-11.FindingsWe found patients in high PARP-1 expression group had higher levels of blast cells in bone marrow (P = .003) and white blood cells (WBC) in peripheral blood (P = .008), and were associated with a more frequent FLT3-ITD mutation (28.2% vs 17.3%, P = .031). The overall survival (OS) and event free survival (EFS) of the high expression group were significantly shorter than those in the low expression group (OS, P = .005 and EFS, P = .004). BMN673 combined with NL101 had a strong synergistic effect in treating AML. The combination significantly induced cell apoptosis and arrested cell cycle in G2/M phase. Mechanistically, BMN673 and NL101 combinatorial treatment promoted DNA damage. In vivo, the combination effectively delayed the development of AML and prolonged survival.InterpretationHigh PARP-1 expression predicts poor survival in CN-AML patients. The synergistic effects of PARP inhibitor BMN673 in combination with SAHA-bendamustine hybrid, NL101, provide a new therapeutic strategy against AML.FundNational Natural Science Foundation of China and Zhejiang Provincial Key Innovation Team.

Background Telocytes play key roles in maintenance of organ/tissue function and prevention of organ injury. However, there are great challenges to investigate telocytes functions using primary telocytes, due to the difficulties of isolation, identification, and stability. The present study aims at constructing continuous cell strain of mouse lung telocyte cell line with stable characters by gene modification and investigating biological behaviors and responses of gene-modified telocytes to inflammation. Methods Mouse primary lung telocytes were isolated and identified using immune-labeling markers and immunoelectron microscopy. Primary telocytes were transformed with Simian vacuolating virus 40 small and large T antigen (SV40). Biological characters, behaviors morphology, and proliferation of those gene-modified telocytes were defined and monitored dynamically for 50 generations, as compared with primary lung telocytes. Cell cycle of mouse primary lung telocytes or gene-modified telocytes was detected by flow cytometry. Results Gene modified telocytes of generations 5, 10, 30 and 50 were observed with telopodes and also showed CD34 and ckit positive. Multiple cellular morphology were also observed on telocyte cell-line under monitor of celliq and enhanced cell proliferation were showed. SV40 transduction was also reduced apoptosis and increased the ratio of S and G2 phases in telocyte cell-line. Conclusion We successfully constructed mouse lung telocyte cell-line which maintained the biological properties and behaviors as primary telocytes and could responses to inflammation induced by LPS. Thus, gene-modified lung telocytes, Telocyte Line, would provide a cell tool for researchers exploring the roles and applications of telocytes involved in physiological and pathological states in future. Electronic supplementary material The online version of this article (10.1186/s12967-019-1870-y) contains supplementary material, which is available to authorized users.

SETD2, an epigenetic tumor suppressor, is frequently mutated in MLL-rearranged (MLLr) leukemia and relapsed acute leukemia (AL). To clarify the impact of SETD2 mutations on chemotherapy sensitivity in MLLr leukemia, two loss-of-function (LOF) Setd2-mutant alleles (Setd2F2478L/WT or Setd2Ex6-KO/WT) were generated and introduced, respectively, to the Mll-Af9 knock-in leukemia mouse model. Both alleles cooperated with Mll-Af9 to accelerate leukemia development that resulted in resistance to standard Cytarabine-based chemotherapy. Mechanistically, Setd2-mutant leukemic cells showed downregulated signaling related to cell cycle progression, S, and G2/M checkpoint regulation. Thus, after Cytarabine treatment, Setd2-mutant leukemic cells exit from the S phase and progress to the G2/M phase. Importantly, S and G2/M cell cycle checkpoint inhibition could resensitize the Mll-Af9/Setd2 double-mutant cells to standard chemotherapy by causing DNA replication collapse, mitotic catastrophe, and increased cell death. These findings demonstrate that LOF SETD2 mutations confer chemoresistance on AL to DNA-damaging treatment by S and G2/M checkpoint defects. The combination of S and G2/M checkpoint inhibition with chemotherapy can be explored as a promising therapeutic strategy by exploiting their unique vulnerability and resensitizing chemoresistant AL with SETD2 or SETD2-like epigenetic mutations.