An Electrolyte with Less Space-Occupying Diluent at Cathode Inner Helmholtz Plane for Stable 4.6†V Lithium-Ion Batteries.

Reasonably elevating the working voltage (≥4.4 V vs. Li/Li+ ) of the cathode is one of the efficient approaches to maximize the energy density of lithium-ion batteries (LIBs). As a preferred partner for high-voltage LIB systems, localized high-concentration electrolyte (LHCE), characterized by a stronger Li solvation structure, less free solvent, and robust electrode/electrolyte interphase has attracted much attention in academic circles. Herein, we systematically studied the role of the diluent in LHCE on the formation of the cathode electrolyte interphase (CEI) and elucidated that the existing anion-diluent pairing in the inner Helmholtz plane (IHP) results in an uneven CEI and subsequent battery degradation under high voltage. A m-fluorotoluene (mFT) diluent was further employed in the LHCE containing lithium difluoro(oxalato)borate (LiDFOB) to facilitate a uniform and rich-anion-derived CEI, since the weaker interaction of HmFT -BDFOB - , as compared to the HHhydrofluoroether -BDFOB - , reduces the influence of mFT in IHP or initial CEI formation. Consequently, the mFT-dominated LHCE propels the high-voltage performance of LIBs one step forward, endowing a 4.6 V-class 1.2-Ah graphite||LiNi0.8 Co0.1 Mn0.1 O2 pouch cells a 90.4 % capacity retention after 130 cycles. Our study thus describes a new index affecting the CEI formation and proposes novel strategies to deeply optimize the high-voltage LIBs.

MYC2 Regulates the Termination of Jasmonate Signaling via an Autoregulatory Negative Feedback Loop.

In tomato (Solanum lycopersicum), as in other plants, the immunity hormone jasmonate (JA) triggers genome-wide transcriptional changes in response to pathogen and insect attack. These changes are largely regulated by the basic helix-loop-helix (bHLH) transcription factor MYC2. The function of MYC2 depends on its physical interaction with the MED25 subunit of the Mediator transcriptional coactivator complex. Although much has been learned about the MYC2-dependent transcriptional activation of JA-responsive genes, relatively less studied is the termination of JA-mediated transcriptional responses and the underlying mechanisms. Here, we report an unexpected function of MYC2 in regulating the termination of JA signaling through activating a small group of JA-inducible bHLH proteins, termed MYC2-TARGETED BHLH1 (MTB1), MTB2, and MTB3. MTB proteins negatively regulate JA-mediated transcriptional responses via their antagonistic effects on the functionality of the MYC2-MED25 transcriptional activation complex. MTB proteins impair the formation of the MYC2-MED25 complex and compete with MYC2 to bind to its target gene promoters. Therefore, MYC2 and MTB proteins form an autoregulatory negative feedback circuit to terminate JA signaling in a highly organized manner. We provide examples demonstrating that gene editing tools such as CRISPR/Cas9 open up new avenues to exploit MTB genes for crop protection.

Clinical Observation of Prophylactic Extended-Field Intensity-Modulated Radiation Therapy with Synchronous Chemotherapy in Locally Advanced Cervical Cancer.

BACKGROUND We aimed to evaluate the value of prophylactic extended-field intensity-modulated radiation therapy (IMRT) in the treatment of locally advanced cervical cancer with multiple pelvic lymph node metastases (≥2) and negative common iliac and paraaortic lymph nodes. MATERIAL AND METHODS Thirty-four patient with newly diagnosed cervical cancer (IB1-IVA) and multiple pelvic lymph node metastases (≥2) confirmed by computed tomography and magnetic resonance imaging were randomly divided into an extended-field group (17 patients) and a pelvic-field group (17 patients). In the extended-field group, we added the drainage area of paraaortic lymph nodes on the pelvic field. The pelvic field was administered Dt 45.0 to 50.4 Gy, while the drainage area of paraaortic lymph nodes was administered Dt 40.0 to 45.0 Gy. Both groups were given Irl92 intracavitary radiotherapy after 3 weeks of external irradiation. The total dose of point A was 25.0 to 30.0 Gy, fractional 6.0 to 7.0 Gy. All patients had concurrent platinum-based chemotherapy once weekly until the end of radiotherapy. RESULTS No paraaortic lymph node metastasis was found in the extended-field group (P=0.0184), and disease-free survival (DFS) was prolonged (P=0.0286). Adverse effects in patients with III-IV degree myelosuppression were increased in the extended-field group (P=0.0324). However, all patients recovered after symptomatic treatment. CONCLUSIONS Prophylactic extended-field IMRT with chemotherapy reduced the metastasis rate of paraaortic lymph nodes and prolonged the DFS in patients with locally advanced cervical cancer and multiple pelvic lymph node metastases (≥2), while the toxic adverse effects were tolerated.

Mediator subunit MED31 is required for radial patterning of Arabidopsis roots.

Stem cell specification in multicellular organisms relies on the precise spatiotemporal control of RNA polymerase II (Pol II)-dependent gene transcription, in which the evolutionarily conserved Mediator coactivator complex plays an essential role. In Arabidopsis thaliana, SHORTROOT (SHR) and SCARECROW (SCR) orchestrate a transcriptional program that determines the fate and asymmetrical divisions of stem cells generating the root ground tissue. The mechanism by which SHR/SCR relays context-specific regulatory signals to the Pol II general transcription machinery is unknown. Here, we report the role of Mediator in controlling the spatiotemporal transcriptional output of SHR/SCR during asymmetrical division of stem cells and ground tissue patterning. The Mediator subunit MED31 interacted with SCR but not SHR. Reduction of MED31 disrupted the spatiotemporal activation of CYCLIND6;1 (CYCD6;1), leading to defective asymmetrical division of stem cells generating ground tissue. MED31 was recruited to the promoter of CYCD6;1 in an SCR-dependent manner. MED31 was involved in the formation of a dynamic MED31/SCR/SHR ternary complex through the interface protein SCR. We demonstrate that the relative protein abundance of MED31 and SHR in different cell types regulates the dynamic formation of the ternary complex, which provides a tunable switch to strictly control the spatiotemporal transcriptional output. This study provides valuable clues to understand the mechanism by which master transcriptional regulators control organ patterning.

BRG1 deficiency in endothelial cells alleviates thioacetamide induced liver fibrosis in mice.

Liver sinusoidal endothelial cells play a key role maintaining the hepatic homeostasis, the disruption of which is associated with such end-stage liver diseases as hepatocellular carcinoma and cirrhosis. In the present study we investigated the role of brahma-related gene 1 (BRG1), a chromatin remodeling protein, in regulating endothelial transcription and the implication in liver fibrosis. We report that endothelial-specific deletion of BRG1 in mice attenuated liver fibrosis induced by injection with thioacetamide (TAA). Coincidently, alleviation of liver fibrosis as a result of endothelial BRG1 deletion was accompanied by an up-regulation of eNOS activity and NO bioavailability. In cultured endothelial cells, exposure to lipopolysaccharide (LPS) suppressed eNOS activity whereas BRG1 depletion with small interfering RNA restored eNOS-dependent NO production. Further analysis revealed that BRG1 was recruited to the caveolin-1 (CAV1) promoter by Sp1 and activated transcription of CAV1, which in turn inhibited eNOS activity. Mechanistically, BRG1 interacted with the H3K4 trimethyltransferase MLL1 to modulate H3K4 trimethylation surrounding the CAV1 promoter thereby contributing to LPS-induced CAV1 activation. In conclusion, our data unveil a novel role for BRG1 in the regulation of endothelial function and liver fibrosis.

Megakaryocytic Leukemia 1 Bridges Epigenetic Activation of NADPH Oxidase in Macrophages to Cardiac Ischemia-Reperfusion Injury.

BACKGROUND: Excessive accumulation of reactive oxygen species (ROS), catalyzed by the NADPH oxidases (NOX), is involved in the pathogenesis of ischemia-reperfusion (IR) injury. The underlying epigenetic mechanism remains elusive. METHODS: We evaluated the potential role of megakaryocytic leukemia 1 (MKL1), as a bridge linking epigenetic activation of NOX to ROS production and cardiac ischemia-reperfusion injury. RESULTS: Following IR injury, MKL1-deficient (knockout) mice exhibited smaller myocardial infarction along with improved heart function compared with wild-type littermates. Similarly, pharmaceutical inhibition of MKL1 with CCG-1423 also attenuated myocardial infarction and improved heart function in mice. Amelioration of IR injury as a result of MKL1 deletion or inhibition was accompanied by reduced ROS in vivo and in vitro. In response to IR, MKL1 levels were specifically elevated in macrophages, but not in cardiomyocytes, in the heart. Of note, macrophage-specific deletion (MϕcKO), instead of cardiomyocyte-restricted ablation (CMcKO), of MKL1 in mice led to similar improvements of infarct size, heart function, and myocardial ROS generation. Reporter assay and chromatin immunoprecipitation assay revealed that MKL1 directly bound to the promoters of NOX genes to activate NOX transcription. Mechanistically, MKL1 recruited the histone acetyltransferase MOF (male absent on the first) to modify the chromatin structure surrounding the NOX promoters. Knockdown of MOF in macrophages blocked hypoxia/reoxygenation-induced NOX transactivation and ROS accumulation. Of importance, pharmaceutical inhibition of MOF with MG149 significantly downregulated NOX1/NOX4 expression, dampened ROS production, and normalized myocardial function in mice exposed to IR injury. Finally, administration of a specific NOX1/4 inhibitor GKT137831 dampened ROS generation and rescued heart function after IR in mice. CONCLUSIONS: Our data delineate an MKL1-MOF-NOX axis in macrophages that contributes to IR injury, and as such we have provided novel therapeutic targets in the treatment of ischemic heart disease.

An interaction between BRG1 and histone modifying enzymes mediates lipopolysaccharide-induced proinflammatory cytokines in vascular endothelial cells.

Vascular inflammation is the culprit for a host of human diseases. The underlying mechanism, however, is not definitively elucidated. In the present study, we investigated the interplay between different epigenetic factors during lipopolysaccharide (LPS) induced synthesis of proinflammatory cytokines in cultured vascular endothelial cells. We report that in response to LPS treatment, NF-κB was deplored to its target promoters along with the chromatin remodeling protein BRG1. Paralleling these changes trimethylated H3K9 became erased from while trimethylated H3K4 started to accumulate on the NF-κB target promoters. Further analysis revealed that LPS stimulation resulted in sequential recruitment of the H3K9 tri-demethylase JMJD2A and the H3K4 trimethyltransferase SET1A to the NF-κB target promoters. JMJD2A mediated-H3K9 demethylation served as a prerequisite for SET1A to bind to the NF-κB target promoters. Both JMJD2A and SET1A were essential for LPS-induced transactivation of proinflammatory cytokines by sustaining the binding of NF-κB. Of key importance, BRG1 coordinated the sequential recruit of and the interplay between JMJD2A and SET1A. In conclusion, our data unveil a novel epigenetic mechanism that contributes to LPS-induced vascular inflammation.

Hepatocyte-specific deletion of Brg1 alleviates methionine-and-choline-deficient diet (MCD) induced non-alcoholic steatohepatitis in mice.

Uncontrolled inflammatory response and augmented lipid accumulation represent two key pathophysiological events in the pathogenesis of non-alcoholic steatohepatitis (NASH). NF-κB and SREBP1c program transcriptional regulation of cellular inflammatory response and lipid metabolism, respectively. The epigenetic mechanism underlying NF-κB-dependent pro-inflammatory transcription and SREBP1c-dependent pro-lipogenic transcription remains incompletely understood. In the present study we investigated the involvement of Brg1, a chromatin remodeling protein, in NASH pathogenesis in a methionine-and-choline deficient diet (MCD) induced mouse model. Brg1 expression was up-regulated in the liver in mice fed on the MCD diet and in primary hepatocytes exposed to free fatty acids. Liver injury and hepatic inflammation attenuated in hepatocyte-specific Brg1 knockout (CKO) mice fed on the MCD diet compared to the wild type (WT) littermates. Likewise, synthesis of pro-inflammatory mediators was down-regulated in primary hepatocytes isolated from CKO mice compared to WT mice, which resulted in reduced macrophage chemotaxis. Brg1 contributed to the transcription of pro-inflammatory mediators possibly by regulating the interaction between NF-κB and its co-factor MRTF-A. On the other hand, accumulation of triglyceride and cholesterol was ameliorated in MCD-fed CKO mice with a concomitant reduction of SREBP1c target genes. Brg1 interacted with SREBP1c and modulated the transcription of SREB1c target genes in the liver in response to MCD feeding by influencing active histone modifications. In conclusion, targeting Brg1 may yield novel anti-NASH therapeutics by simultaneously normalizing hepatic inflammatory status and metabolic profile in NASH patients.

The histone methyltransferase Suv39h2 contributes to nonalcoholic steatohepatitis in mice.

Uncontrolled inflammatory response highlights the central theme of nonalcoholic steatohepatitis (NASH), a growing global pandemic. Hepatocytes and macrophages represent two major sources of hepatic inflammation during NASH pathogenesis, contributing to excessive synthesis of proinflammatory mediators. The epigenetic mechanism that accounts for the activation of hepatocytes and macrophages in this process remains obscure. Here, we report that compared to wild-type littermates, mice with a deficiency in the histone H3K9 methyltransferase suppressor of variegation 39 homolog 2 (Suv39h2, knockout) exhibited a less severe form of NASH induced by feeding with a high-fat, high-carbohydrate diet. Pro-NASH stimuli increased Suv39h2 expression in cell culture, in mice, and in human livers. In hepatocytes, Suv39h2 bound to the Sirt1 gene promoter and repressed Sirt1 transcription. Suv39h2 deficiency normalized Sirt1 expression, allowing nuclear factor kappa B/p65 to become hypoacetylated and thus dampening nuclear factor kappa B-dependent transcription of proinflammatory mediators. In macrophages, Suv39h2-mediated repression of peroxisome proliferator-activated receptor gamma transcription favored a proinflammatory M1 phenotype over an anti-inflammatory M2 phenotype, thereby elevating hepatic inflammation. CONCLUSION: Suv39h2 plays a pivotal role in the regulation of inflammatory response in hepatocytes and macrophages, contributing to NASH pathogenesis. (Hepatology 2017;65:1904-1919).

Angiogenic Factor With G Patch and FHA Domains 1 Is a Novel Regulator of Vascular Injury.

OBJECTIVE: Phenotypic modulation of vascular smooth muscle cells represents a hallmark event in vascular injury. The underlying mechanism is not completely sorted out. We investigated the involvement of angiogenic factor with G patch and FHA domains 1 (Aggf1) in vascular injury focusing on the transcriptional regulation of vascular smooth muscle cell signature genes. APPROACH AND RESULTS: We report here that Aggf1 expression was downregulated in several different cell models of phenotypic modulation in vitro and in the vessels after carotid artery ligation in mice. Adenovirus-mediated Aggf1 overexpression dampened vascular injury and normalized vascular smooth muscle cell signature gene expression. Mechanistically, Aggf1 interacted with myocardin and was imperative for the formation of a serum response factor-myocardin complex on gene promoters. In response to injurious stimuli, kruppel-like factor 4 was recruited to the Aggf1 promoter and enlisted histone deacetylase 11 to repress Aggf1 transcription. In accordance, depletion of kruppel-like factor 4 or histone deacetylase 11 restored Aggf1 expression and abrogated vascular smooth muscle cell phenotypic modulation. Finally, treatment of a histone deacetylase 11 inhibitor attenuated vascular injury in mice. CONCLUSIONS: Therefore, we have unveiled a previously unrecognized role for Aggf1 in regulating vascular injury.

ATRA Regulates Innate Immunity in Liver Ischemia/Reperfusion Injury via RARα/Akt/Foxo1 Signaling.

All-trans retinoic acid (ATRA) has been proved to protect liver from ischemia/reperfusion (IR) injury, however, its mechanism is still unclear. This study is to investigate the mechanism of effect of ATRA on innate immunity in mice liver IR injury. Before operation, mice were gavaged by ATRA at 15 mg/kg/d for two weeks, and then the liver was underwent 70% ischemia (90 min) and reperfusion (6 h). Liver function was assessed by serum alanine aminotransferase (sALT), serum aspartate aminotransferase (sAST). Real-time PCR and Western blot were to detect the level of mRNA and protein. In vitro, RAW264.7 macrophages were treatment with ATRA (1 µM) or LE540 (5 µM, a retinoic acid receptor α (RARα) receptor antagonist) before lipopolysaccharide (100 ng/mL) stimulation. In vivo, ATRA protected the liver from IR injury by improving hepatocellular function (sALT and sAST), decreasing cell apoptosis and inhibiting inflammatory response (i.e., the level of toll-like receptor 4, transcription factor nuclear factor-κBp65, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α). When RARα was blocked by LE540 in RAW264.7 macrophages, the inflammatory cytokines were enhancing, along with a decline of Akt phosphorylation but Forkhead box o (Foxo) 1, compared with the ATRA group. In summary, ATRA regulates in part the innate immunity to protect liver from IR injury by RARα/Akt/Foxo1 pathway.

Angiogenic factor with G patch and FHA domains 1 (Aggf1) regulates liver fibrosis by modulating TGF-ß signaling.

Fibrosis is a common pathophysiological process following liver injury and can lead to, if left unattended to, irreversible end-stage liver disease such as cirrhosis. Hepatic stellate cells (HSCs) are a major contributor to liver fibrosis. Here we investigated the involvement of angiogenic factor with G patch and FHA domains 1 (Aggf1) in HSC activation and the underlying mechanisms. Aggf1 expression was down-regulated in the livers in three different mouse models of liver fibrosis following injury. Aggf1 expression was also suppressed in activated HSCs when compared to quiescent HSCs. Over-expression of Aggf1 alleviated liver fibrosis in mice and in cultured HSCs. RNA-sequencing (RNA-seq) analysis performed in HSCs revealed that Aggf1-dependent transcription regulates several key fibrogenic pathways. Mechanistically, Aggf1 regulated liver fibrogenesis by forming a complex with the inhibitor SMAD protein (SMAD7) thereby leading to diminished SMAD3 binding to the pro-fibrogenic gene promoters. On the contrary, SMAD7 knockdown abrogated the effect of Aggf1 and rescued HSC activation. Aggf1 expression was silenced during HSC activation/liver fibrogenesis as a result of DNA methylation. Treatment with a DNA methyltransferase inhibitor (5-Azacytidine) restored Aggf1 expression and repressed liver fibrosis in an Aggf1-dependent manner. In conclusion, our data illustrate a previously unknown role for Aggf1 and shed light on the development of novel therapeutic solutions against liver fibrosis.

The arginine methyltransferase PRMT5 regulates CIITA-dependent MHC II transcription.

Class II major histocompatibility complex (MHC II) dependent antigen presentation serves as a key step in mammalian adaptive immunity and host defense. In antigen presenting cells (e.g., macrophages), MHC II transcription can be activated by interferon gamma (IFN-γ) and mediated by class II transactivator (CIITA). The underlying epigenetic mechanism, however, is not completely understood. Here we report that following IFN-γ stimulation, symmetrically dimethylated histone H3 arginine 2 (H3R2Me2s) accumulated on the MHC II promoter along with CIITA. IFN-γ augmented expression, nuclear translocation, and promoter binding of the protein arginine methyltransferase PRMT5 in macrophages. Over-expression of PRMT5 potentiated IFN-γ induced activation of MHC II transcription in an enzyme activity-dependent manner. In contrast, PRMT5 silencing or inhibition of PRMT5 activity by methylthioadenosine (MTA) suppressed MHC II transactivation by IFN-γ. CIITA interacted with and recruited PRMT5 to the MHC II promoter and mediated the synergy between PRMT5 and ASH2/WDR5 to activate MHC II transcription. PRMT5 expression was down-regulated in senescent and H2O2-treated macrophages rendering ineffectual induction of MHC II transcription by IFN-γ. Taken together, our data reveal a pathophysiologically relevant role for PRMT5 in MHC II transactivation in macrophages.

HDAC4 mediates IFN-γ induced disruption of energy expenditure-related gene expression by repressing SIRT1 transcription in skeletal muscle cells.

Metabolic homeostasis is achieved through balanced energy storage and output. Impairment of energy expenditure is a hallmark event in patients with obesity and type 2 diabetes. Previously we have shown that the pro-inflammatory cytokine interferon gamma (IFN-γ) disrupts energy expenditure in skeletal muscle cells via hypermethylated in cancer 1 (HIC1)-class II transactivator (CIITA) dependent repression of SIRT1 transcription. Here we report that repression of SIRT1 transcription by IFN-γ paralleled loss of histone acetylation on the SIRT1 promoter region with simultaneous recruitment of histone deacetylase 4 (HDAC4). IFN-γ activated HDAC4 in vitro and in vivo by up-regulating its expression and stimulating its nuclear accumulation. HIC1 and CIITA recruited HDAC4 to the SIRT1 promoter and cooperated with HDAC4 to repress SIRT1 transcription. HDAC4 depletion by small interfering RNA or pharmaceutical inhibition normalized histone acetylation on the SIRT1 promoter and restored SIRT1 expression in the presence of IFN-γ. Over-expression of HDAC4 suppressed the transcription of genes involved in energy expenditure in a SIRT1-dependent manner. In contrast, HDAC4 knockdown/inhibition neutralized the effect of IFN-γ on cellular metabolism by normalizing SIRT1 expression. Therefore, our data reveal a role for HDAC4 in regulating cellular energy output and as such provide insights into rationalized design of novel anti-diabetic therapeutics.

MKL1 links epigenetic activation of MMP2 to ovarian cancer cell migration and invasion.

Responding to pro-metastatic cues such as low oxygen tension, cancer cells develop several different strategies to facilitate migration and invasion. During this process, expression levels of matrix metalloproteinases (MMPs) are up-regulated so that cancer cells can more easily enter or exit the circulation. In this report we show that message levels of the transcriptional modulator MKL1 were elevated in malignant forms of ovarian cancer tissues in humans when compared to more benign forms accompanying a similar change in MMP2 expression. MKL1 silencing blocked hypoxia-induced migration and invasion of ovarian cancer cells (SKOV-3) in vitro. Over-expression of MKL1 activated while MKL1 depletion repressed MMP2 transcription in SKOV-3 cells. MKL1 was recruited to the MMP2 promoter by NF-κB in response to hypoxia. Mechanistically, MKL1 recruited a histone methyltransferase, SET1, and a chromatin remodeling protein, BRG1, and coordinated their interaction to alter the chromatin structure surrounding the MMP2 promoter leading to transcriptional activation. Both BRG1 and SET1 were essential for hypoxia-induced MMP2 trans-activation. Finally, expression levels of SET1 and BRG1 were positively correlated with ovarian cancer malignancies in humans. Together, our data suggest that MKL1 promotes ovarian cancer cell migration and invasion by epigenetically activating MMP2 transcription.

Suv39h2 deficiency ameliorates diet-induced steatosis in mice.

Steatosis is a prototypical metabolic disorder characterized by accumulation of lipid droplets in the liver, extensive hepatic inflammation, and, in advanced stages, accelerated liver fibrogenesis. The molecular mechanism underlying steatosis is not completely understood. In the present study we investigated the involvement of the histone methyltransferase Suv39h2 in the pathogenesis of steatosis. Expression of Suv39h2 was up-regulated in the liver in two different mouse models of steatosis. Suv39h2 knockout (KO) mice developed a less severe form of steatosis fed on a methione-and-choline deficient (MCD) diet, compared to wild type (WT) littermates, as evidenced by reduced levels of plasma ALT, down-regulated expression of pro-inflammatory mediators, and decreased infiltration of macrophages. In addition, Masson's trichrome staining as well as qPCR measurements of fibrogenic genes suggested that liver fibrosis was attenuated in MCD diet-fed KO mice compared to WT mice. Further analysis found that Suv39h2 repressed SIRT1 expression in the liver by stimulating histone H3K9 trimethylation surrounding the SIRT1 promoter and that Suv39h2 deficiency alleviated SIRT1 expression in MCD diet-fed mice. Therefore, our data support a role of Suv39h2 in promoting steatosis in mice likely through contributing to SIRT1 trans-reperssion.

SUV39H1 mediated SIRT1 trans-repression contributes to cardiac ischemia-reperfusion injury.

Ischemic reperfusion (I/R) contributes to deleterious cardiac remodeling and heart failure. The deacetylase SIRT1 has been shown to protect the heart from I/R injury. We examined the mechanism whereby I/R injury represses SIRT1 transcription in the myocardium. There was accumulation of trimethylated histone H3K9 on the proximal SIRT1 promoter in the myocardium in mice following I/R injury and in cultured cardiomyocytes exposed to hypoxia-reoxygenation (H/R). In accordance, the H3K9 trimethyltransferase SUV39H1 bound to the SIRT1 promoter and repressed SIRT1 transcription. SUV39H1 expression was up-regulated in the myocardium in mice following I/R insults and in H/R-treated cardiomyocytes paralleling SIRT1 down-regulation. Silencing SUV39H1 expression or suppression of SUV39H1 activity erased H3K9Me3 from the SIRT1 promoter and normalized SIRT1 levels in cardiomyocytes. Meanwhile, SUV39H1 deficiency or inhibition attenuated I/R-induced infarction and improved heart function in mice likely through influencing ROS levels in a SIRT1-dependent manner. Therefore, our data uncover a novel mechanism for SIRT1 trans-repression during cardiac I/R injury and present SUV39H1 as a druggable target for the development of therapeutic strategies against ischemic heart disease.

A2b adenosine signaling represses CIITA transcription via an epigenetic mechanism in vascular smooth muscle cells.

Chronic inflammation plays a major role in the pathogenesis of atherosclerosis. Vascular smooth muscle cells (VSMC), by expressing and presenting major histocompatibility complex II (MHC II) molecules, help recruit T lymphocyte and initiate the inflammatory response within the vasculature. We have previously shown that VSMCs isolated from mice with deficient adenosine A2b receptor (A2b-null) exhibit higher expression of class II transactivator (CIITA), the master regulator of MHC II transcription, compared to wild type littermates. Here we report that activation of A2b adenosine signaling suppresses CIITA expression in human aortic smooth muscle cells. Down-regulation of CIITA expression was largely attributable to transcriptional repression of type III and IV promoters. Chromatin immunoprecipitation (ChIP) analyses revealed that A2b signaling repressed CIITA transcription by attenuating specific histone modifications on the CIITA promoters in a STAT1-dependent manner. STAT1 interacted with PCAF/GCN5, histone H3K9 acetyltransferases, and WDR5, a key component of the mammalian H3K4 methyltransferase complex, to activate CIITA transcription. A2b signaling prevented recruitment of PCAF/GCN5 and WDR5 to the CIITA promoters in a STAT1-dependent manner. In conclusion, our data suggest that adenosine A2b signaling represses CIITA transcription in VSMCs by manipulating the interaction between STAT1 and the epigenetic machinery.

MKL1 is an epigenetic modulator of TGF-ß induced fibrogenesis.

Transforming growth factor (TGF-ß) induced activation of portal fibroblast cells serves as a primary cause for liver fibrosis following cholestatic injury. The underlying epigenetic mechanism is not clear. We studied the role of a transcriptional modulator, megakaryoblastic leukemia 1 (MKL1) in this process. We report here that MKL1 deficiency ameliorated BDL-induced liver fibrosis in mice as assessed by histological stainings and expression levels of pro-fibrogenic genes. MKL1 silencing by small interfering RNA (siRNA) abrogated TGF-ß induced transactivation of pro-fibrogenic genes in portal fibroblast cells. TGF-ß stimulated the binding of MKL1 on the promoters of pro-fibrogenic genes and promoted the interaction between MKL1 and SMAD3. While SMAD3 was necessary for MKL1 occupancy on the gene promoters, MKL1 depletion impaired SMAD3 binding reciprocally. TGF-ß treatment induced the accumulation of trimethylated histone H3K4 on the gene promoters by recruiting a methyltransferase complex. Knockdown of individual members of this complex significantly weakened the binding of SMAD3 and down-regulated the activation of portal fibroblast cells. In conclusion, we have identified an epigenetic pathway that dictates TGF-ß induced pro-fibrogenic transcription in portal fibroblast thereby providing novel insights for the development of therapeutic solutions to treat liver fibrosis.

MRTF-A mediates LPS-induced pro-inflammatory transcription by interacting with the COMPASS complex.

Chronic inflammation underscores the pathogenesis of a range of human diseases. Lipopolysaccharide (LPS) elicits strong pro-inflammatory responses in macrophages through the transcription factor NF-κB. The epigenetic mechanism underlying LPS-induced pro-inflammatory transcription is not fully understood. Herein, we describe a role for myocardin-related transcription factor A (MRTF-A, also known as MKL1) in this process. MRTF-A overexpression enhanced NF-κB-dependent pro-inflammatory transcription, whereas MRTF-A silencing inhibited this process. MRTF-A deficiency also reduced the synthesis of pro-inflammatory mediators in a mouse model of colitis. LPS promoted the recruitment of MRTF-A to the promoters of pro-inflammatory genes in an NF-κB-dependent manner. Reciprocally, MRTF-A influenced the nuclear enrichment and target binding of NF-κB. Mechanistically, MRTF-A was necessary for the accumulation of active histone modifications on NF-κB target promoters by communicating with the histone H3K4 methyltransferase complex (COMPASS). Silencing of individual members of COMPASS, including ASH2, WDR5 and SET1 (also known as SETD1A), downregulated the production of pro-inflammatory mediators and impaired the NF-κB kinetics. In summary, our work has uncovered a previously unknown function for MRTF-A and provided insights into the rationalized development of anti-inflammatory therapeutic strategies.