SET7/9 Enzyme Regulates Cytokine-induced Expression of Inducible Nitric-oxide Synthase through Methylation of Lysine 4 at Histone 3 in the Islet β Cell

Histone modifications and their roles in macrophage-mediated inflammation: a new target for diabetic wound healing

Impaired wound healing is one of the main clinical complications of type 2 diabetes (T2D) and a major cause of lower limb amputation. Diabetic wounds exhibit a sustained inflammatory state, and reducing inflammation is crucial to diabetic wounds management. Macrophages are key regulators in wound healing, and their dysfunction would cause exacerbated inflammation and poor healing in diabetic wounds. Gene regulation caused by histone modifications can affect macrophage phenotype and function during diabetic wound healing. Recent studies have revealed that targeting histone-modifying enzymes in a local, macrophage-specific manner can reduce inflammatory responses and improve diabetic wound healing. This article will review the significance of macrophage phenotype and function in wound healing, as well as illustrate how histone modifications affect macrophage polarization in diabetic wounds. Targeting macrophage phenotype with histone-modifying enzymes may provide novel therapeutic strategies for the treatment of diabetic wound healing.

Epigenetic mechanism of SET7/9-mediated histone methylation modification in high glucose-induced ferroptosis in retinal pigment epithelial cells

Ferroptosis of the retinal pigment epithelial (RPE) cells leads to retinal neuron injury and even visual loss. Our study aims to investigate the role of the SET domain with lysine methyltransferase 7/9 (SET7/9) in regulating high glucose (HG)-induced ferroptosis in RPE cells. The cell model was established by HG treatment. The levels of SET7/9 and Sirtuin 6 (SIRT6) were inhibited and Runt-related transcription factor 1 (RUNX1) was overexpressed through cell transfection, and then their levels in ARPE-19 cells were detected. Cell viability and apoptosis was detected. The levels of reactive oxygen species, malondialdehyde, glutathione, ferrous ion, glutathione peroxidase 4, and acyl-CoA synthetase long-chain family member 4 were detected. SET7/9 and trimethylation of histone H3 at lysine 4 (H3K4me3) levels in the RUNX1 promoter region and RUNX1 level in the SIRT6 promoter region were measured. The relationship between RUNX1 and SIRT6 was verified. SET7/9 and RUNX1 were highly expressed while SIRT6 was poorly expressed in HG-induced ARPE-19 cells. SET7/9 inhibition increased cell viability and inhibited cell apoptosis and ferroptosis. Mechanistically, SET7/9 increased H3K4me3 on the RUNX1 promoter to promote RUNX1, and RUNX1 repressed SIRT6 expression. Overexpression of RUNX1 or silencing SIRT6 partially reversed the inhibitory effect of SET7/9 silencing on HG-induced ferroptosis. In conclusion, SET7/9 promoted ferroptosis of RPE cells through the SIRT6/RUNX1 pathway.

ZKSCAN5 activates LAPTM5 expression by recruiting SETD7 to promote metastasis in pancreatic ductal adenocarcinoma

Lysosomal-associated transmembrane protein 5 (LAPTM5) has been associated with poor prognosis in cancer patients. Its role in regulating metastasis in pancreatic ductal adenocarcinoma (PDAC), however, remains vague. The study here aimed to expound the metastasis-promoting properties of LAPTM5 in PDAC and the detailed mechanism. LAPTM5 was overexpressed in metastatic PDAC cells and was related to the dismal prognosis of patients in GEO datasets. By using lentiviral vectors harboring short hairpin RNA, we found that LAPTM5 downregulation reduced PDAC cell viability, proliferation, and aggressiveness in vitro and liver metastasis in vivo. Zinc finger with KRAB and SCAN domains 5 (ZKSCAN5) was predicted and verified to mediate LAPTM5 transcription in PDAC cells. Both ZKSCAN5 and SET domains, containing lysine methyltransferase 7 (SETD7) bound to the LAPTM5 promoter, and ZKSCAN5 recruited SETD7 to form a complex promoting LAPTM5 transcription. LAPTM5 knockdown reversed the promoting effect of ZKSCAN5 on the metastasis of PDAC cells. Thus, our findings on the ZKSCAN5/SETD7/LAPTM5 axis provide insights into the underlying mechanism of liver metastasis dissemination in PDAC.

Methyltransferase Set7/9 as a Multifaceted Regulator of ROS Response

Reactive oxygen species (ROS) induce multiple signaling cascades in the cell and hence play an important role in the regulation of the cell's fate. ROS can cause irreversible damage to DNA and proteins resulting in cell death. Therefore, finely tuned regulatory mechanisms exist in evolutionarily diverse organisms that are aimed at the neutralization of ROS and its consequences with respect to cellular damage. The SET domain-containing lysine methyltransferase Set7/9 (KMT7, SETD7, SET7, SET9) post-translationally modifies several histones and non-histone proteins via monomethylation of the target lysines in a sequence-specific manner. In cellulo, the Set7/9-directed covalent modification of its substrates affects gene expression, cell cycle, energy metabolism, apoptosis, ROS, and DNA damage response. However, the in vivo role of Set7/9 remains enigmatic. In this review, we summarize the currently available information regarding the role of methyltransferase Set7/9 in the regulation of ROS-inducible molecular cascades in response to oxidative stress. We also highlight the in vivo importance of Set7/9 in ROS-related diseases.

[Research Progress of Role and Mechanism of SETD7 in Tumor Occurrence and Progression]

The occurence and development of tumors is a complicated process, which not only depends on the mutation or deletion of genes, but also is affected by epigenetic regulation. Accumulating evidences have shown that epigenetic modifications play fundamental roles in transcriptional regulation, heterochromatin formation, X chromosome inactivation, DNA damage response and tumor development. SET domain containing lysine methyltransferase 7 (SETD7) was initially identified as an important lysine methyltransferase, which methylated histone and non-histone proteins. These modifications play fundamental roles. Once this modification disorders, it can directly lead to cell abnormalities and cause many diseases. Studies have shown that SETD7 is related to the occurence and development of various tumors, but the methylation sites of SETD7 and its regulatory mechanism have not been fully elucidated. This article summarizes the research progress of the role of SETD7 on histone and non-histone methylation modification in tumors and the molecular mechanism, in order to provide new therapeutic targets for tumor pathogenesis and diagnosis.
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The Epigenetic Regulation of Nonhistone Proteins by SETD7: New Targets in Cancer

Epigenetic modifications are essential mechanism by which to ensure cell homeostasis. One such modification is lysine methylation of nonhistone proteins by SETD7, a mono-methyltransferase containing SET domains. SETD7 methylates over 30 proteins and is thus involved in various classical pathways. As such, SETD7 has been implicated in both the basic functions of normal tissues but also in several pathologies, such as cancers. In this review, we summarize the current knowledge of SETD7 substrates, especially transcriptional-related proteins and enzymes, and their putative roles upon SETD7-mediated methylation. We focus on the role of SETD7 in cancers, and speculate on the possible points of intervention and areas for future research.

Nonhistone Lysine Methylation as a Protein Degradation Signal

Protein degradation is a fundamental feature of cellular life, and malfunction of this process is implicated in human disease. Ubiquitin tagging is the best characterized mechanism of targeting a protein for degradation; however, there are a growing number of distinct mechanisms which have also been identified that carry out this essential function. For example, covalent tagging of proteins with sequestosome-1 targets them for selective autophagy. Degradation signals are not exclusively polypeptides such as ubiquitin, NEDD8, and sequestosome-1. Phosphorylation, acetylation, and methylation are small covalent additions that can also direct protein degradation. The diversity of substrate sequences and overlap with other pleotrophic functions for these smaller signaling moieties has made their characterization more challenging. However, these small signals might be responsible for orchestrating a large portion of the protein degradation activity in the cell. As such, there has been increasing interest in lysine methylation and associated lysine methyltransferases (KMTs), beyond canonical histone protein modification, in mediating protein degradation in a variety of contexts. This review focuses on the current evidence for lysine methylation as a protein degradation signal with a detailed discussion of the class of enzymes responsible for this phenomenon.

SetD7 (Set7/9) is a novel target of PPARγ that promotes the adaptive pancreatic β-cell glycemic response

Loss of functional pancreatic β-cell mass leads to type 2 diabetes (T2D), attributable to modified β-cell-dependent adaptive gene expression patterns. SetD7 is a histone methyltransferase enriched in pancreatic islets that mono- and dimethylates histone-3-lysine-4 (H3K4), promoting euchromatin modifications, and also maintains the regulation of key β-cell function and survival genes. However, the transcriptional regulation of this important epigenetic modifier is unresolved. Here we identified the nuclear hormone receptor peroxisome proliferator-activated receptor-gamma (PPARγ) as a major transcriptional regulator of SetD7 and provide evidence for direct binding and functionality of PPARγ in the SetD7 promoter region. Furthermore, constitutive shRNA-mediated PPARγ knockdown in INS-1 β-cells or pancreas-specific PPARγ deletion in mice led to downregulation of SetD7 expression as well as its nuclear enrichment. The relevance of the SetD7-PPARγ interaction in β-cell adaptation was tested in normoglycemic 60% partial pancreatectomy (Px) and hyperglycemic 90% Px rat models. Whereas a synergistic increase in islet PPARγ and SetD7 expression was observed upon glycemic adaptation post-60% Px, in hyperglycemic 90% Px rats, islet PPARγ, and PPARγ targets SetD7 and Pdx1 were downregulated. PPARγ agonist pioglitazone treatment in 90% Px rats partially restored glucose homeostasis and β-cell mass and enhanced expression of SetD7 and Pdx1. Collectively, these data provide evidence that the SetD7-PPARγ interaction serves as an important element of the adaptive β-cell response.

p53-Independent Effects of Set7/9 Lysine Methyltransferase on Metabolism of Non-Small Cell Lung Cancer Cells

Set7/9 is a lysine-specific methyltransferase, which regulates the functioning of both the histone and non-histone substrates, thereby significantly affecting the global gene expression landscape. Using microarray expression profiling, we have identified several key master regulators of metabolic networks, including c-Myc, that were affected by Set7/9 status. Consistent with this observation, c-Myc transcriptional targets-genes encoding the glycolytic enzymes hexokinase (HK2), aldolase (ALDOB), and lactate dehydrogenase (LDHA)-were upregulated upon Set7/9 knockdown (Set7/9KD). Importantly, we showed the short hairpin RNA (shRNA)-mediated attenuation of Set7/9 augmented c-Myc, GLUT1, HK2, ALDOA, and LDHA expression in non-small cell lung cancer (NSCLC) cell lines, not only at the transcriptional but also at the protein level. In line with this observation, Set7/9KD significantly augmented the membrane mitochondrial potential (MMP), glycolysis, respiration, and the proliferation rate of NSCLC cells. Importantly, all these effects of Set7/9 on cell metabolism were p53-independent. Bioinformatic analysis has shown a synergistic impact of Set7/9 together with either GLUT1, HIF1A, HK2, or LDHA on the survival of lung cancer patients. Based on these evidence, we hypothesize that Set7/9 can be an important regulator of energy metabolism in NSCLC.

Histone Methylation Related Therapeutic Challenge in Cardiovascular Diseases

The epidemic of cardiovascular diseases (CVDs) is predicted to spread rapidly in advanced countries accompanied by the high prevalence of risk factors. In terms of pathogenesis, the pathophysiology of CVDs is featured by multiple disorders, including vascular inflammation accompanied by simultaneously perturbed pathways, such as cell death and acute/chronic inflammatory reactions. Epigenetic alteration is involved in the regulation of genome stabilization and cellular homeostasis. The association between CVD progression and histone modifications is widely known. Among the histone modifications, histone methylation is a reversible process involved in the development and homeostasis of the cardiovascular system. Abnormal methylation can promote CVD progression. This review discusses histone methylation and the enzymes involved in the cardiovascular system and determine the effects of histone methyltransferases and demethylases on the pathogenesis of CVDs. We will further demonstrate key proteins mediated by histone methylation in blood vessels and review histone methylation-mediated cardiomyocytes and cellular functions and pathways in CVDs. Finally, we will summarize the role of inhibitors of histone methylation and demethylation in CVDs and analyze their therapeutic potential, based on previous studies.

Low methyl-esterified pectin protects pancreatic β-cells against diabetes-induced oxidative and inflammatory stress via galectin-3

Insufficient intake of dietary fibers in Western societies is considered a major contributing factor in the high incidence rates of diabetes. The dietary fiber pectin has been suggested to be beneficial for management of both Diabetes Type 1 and Type 2, but mechanisms and effects of pectin on insulin producing pancreatic β-cells are unknown. Our study aimed to determine the effects of lemon pectins with different degree of methyl-esterification (DM) on β-cells under oxidative (streptozotocin) and inflammatory (cytokine) stress and to elucidate the underlying rescuing mechanisms, including effects on galectin-3. We found that specific pectins had rescuing effects on toxin and cytokine induced stress on β-cells but effects depended on the pectin concentration and DM-value. Protection was more pronounced with low DM5 pectin and was enhanced with higher pectin-concentrations. Our findings show that specific pectins might prevent diabetes by making insulin producing β-cells less susceptible for stress.

SET7/9 promotes multiple malignant processes in breast cancer development via RUNX2 activation and is negatively regulated by TRIM21

Although the deregulation of lysine methyltransferase (su(var)-3-9, enhancer-of-zeste, trithorax) domain-containing protein 7/9 (SET7/9) has been identified in a variety of cancers, the potential role of SET7/9 and the molecular events in which it is involved in breast cancer remain obscure. Using the online Human Protein Atlas and GEO databases, the expression of SET7/9 was analyzed. Furthermore, we investigated the underlying mechanisms using chromatin immunoprecipitation-based deep sequencing (ChIP-seq) and quantitative ChIP assays. To explore the physiological role of SET7/9, functional analyses such as CCK-8, colony formation, and transwell assays were performed and a xenograft tumor model was generated with the human breast cancer cell lines MCF-7 and MDA-MB-231. Mass spectrometry, co-immunoprecipitation, GST pull-down, and ubiquitination assays were used to explore the mechanisms of SET7/9 function in breast cancer. We evaluated the expression of SET7/9 in different breast cancer cohorts and found that higher expression indicated worse survival times in these public databases. We demonstrated positive effects of SET7/9 on cell proliferation, migration, and invasion via the activation of Runt-related transcription factor 2 (RUNX2). We demonstrate that tripartite motif-containing protein 21 (TRIM21) physically associates with SET7/9 and functions as a major negative regulator upstream of SET7/9 through a proteasome-dependent mechanism and increased ubiquitination. Taken together, our data suggest that SET7/9 has a promoting role via the regulation of RUNX2, whereas TRIM21-mediated SET7/9 degradation acts as an anti-braking system in the progression of breast cancer.

Affinity proteomics identifies novel functional modules related to adhesion GPCRs

Adhesion G protein-coupled receptors (ADGRs) have recently become a target of intense research. Their unique protein structure, which consists of a G protein-coupled receptor combined with long adhesive extracellular domains, suggests a dual role in cell signaling and adhesion. Despite considerable progress in the understanding of ADGR signaling over the past years, the knowledge about ADGR protein networks is still limited. For most receptors, only a few interaction partners are known thus far. We aimed to identify novel ADGR-interacting partners to shed light on cellular protein networks that rely on ADGR function. For this, we applied affinity proteomics, utilizing tandem affinity purifications combined with mass spectrometry. Analysis of the acquired proteomics data provides evidence that ADGRs not only have functional roles at synapses but also at intracellular membranes, namely at the endoplasmic reticulum, the Golgi apparatus, mitochondria, and mitochondria-associated membranes (MAMs). Specifically, we found an association of ADGRs with several scaffold proteins of the membrane-associated guanylate kinases family, elementary units of the γ-secretase complex, the outer/inner mitochondrial membrane, MAMs, and regulators of the Wnt signaling pathways. Furthermore, the nuclear localization of ADGR domains together with their physical interaction with nuclear proteins and several transcription factors suggests a role of ADGRs in gene regulation.

Epigenetics of metabolic syndrome

The dramatic increase in global prevalence of metabolic disease is inexplicable when considering only environmental or only genetic factors, leading to the need to explore the possible roles of epigenetic factors. A great deal of progress has been made in this interdisciplinary field in recent years, with many studies investigating various aspects of the metabolic syndrome and its associated epigenetic changes. Rodent models of metabolic diseases have been particularly illuminating because of the ability to leverage tools such as genetic and environmental modifications. The current review summarizes recent breakthroughs regarding epigenetic markers in studies of obesity, Type II diabetes, and cardiovascular disease, the three major disorders associated with metabolic syndrome. We also discuss open questions and future directions for integrating genomic, epigenomic, and phenotypic big biodata toward understanding metabolic syndrome etiology.

Biological processes and signal transduction pathways regulated by the protein methyltransferase SETD7 and their significance in cancer

Protein methyltransferases have been shown to methylate histone and non-histone proteins, leading to regulation of several biological processes that control cell homeostasis. Over the past few years, the histone-lysine N-methyltransferase SETD7 (SETD7; also known as SET7/9, KIAA1717, KMT7, SET7, SET9) has emerged as an important regulator of at least 30 non-histone proteins and a potential target for the treatment of several human diseases. This review discusses current knowledge of the structure and subcellular localization of SETD7, as well as its function as a histone and non-histone methyltransferase. This work also underlines the putative contribution of SETD7 to the regulation of gene expression, control of cell proliferation, differentiation and endoplasmic reticulum stress, which indicate that SETD7 is a candidate for novel targeted therapies with the aim of either stimulating or inhibiting its activity, depending on the cell signaling context.

Lysine methylation signaling in pancreatic cancer

PURPOSE OF REVIEW

Despite better knowledge of its genetic basis, pancreatic cancer is still highly lethal with very few therapeutic options. In this review, we discuss the potential impact of epigenetic therapies, focusing on lysine methylation signaling and its implication in pancreatic cancer.

RECENT FINDINGS

Protein lysine methylation, a key mechanism of posttranslational modifications of histone proteins, has emerged as a major cell signaling mechanism regulating physiologic and pathologic processes including cancer. This finely tuned and dynamic signaling mechanism is regulated by lysine methyltransferases (KMT), lysine demethylases (KDM) and signal transducers harboring methyl-binding domains. Recent evidence demonstrates that overexpression of cytoplasmic KMT and resulting enhanced lysine methylation is a reversible event that enhances oncogenic signaling through the Ras and Mitogen-Activated Protein Kinases pathway in pancreatic cancer, opening perspectives for new anticancer chemotherapeutics aimed at controlling these activities.

SUMMARY

The development of potent and specific inhibitors of lysine methylation signaling may represent a hitherto largely unexplored avenue for new forms of targeted therapy in cancer, with great potential for yet hard-to-treat cancers such as pancreatic cancer.

Early-Life Social Isolation-Induced Depressive-Like Behavior in Rats Results in Microglial Activation and Neuronal Histone Methylation that Are Mitigated by Minocycline

Early-life stress is a potent risk factor for development of psychiatric conditions such as depression. The underlying mechanisms remain poorly understood. Here, we used the early-life social isolation (ESI) model of early-life stress in rats to characterize development of depressive-like behavior, the role of microglia, levels of histone methylation, as well as expression of glutamate receptor subunits in the hippocampus. We found that depressive-like behavior was induced after ESI as determined by sucrose preference and forced swimming tests. Increased expression of microglial activation marker, Iba1, was observed in the hippocampus of the ESI group, while expression of the microglial CD200 receptor, which promotes microglial quiescence, significantly decreased. In addition, increased levels of proinflammatory cytokines, interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-α) were observed in the hippocampus of the ESI group. Moreover, ESI increased levels of neuronal H3K9me2 (a repressive marker of transcription) and its associated "writer" enzymes, G9a and G9a-like protein, in the hippocampus. ESI also decreased expression of hippocampal NMDA receptor subunits, NR1, and AMPA receptor subunits, GluR1 and GluR2, which are involved in synaptic plasticity, but it did not affect expression of PSD95 and NR2B. Interestingly, treatment with minocycline to block microglial activation induced by ESI inhibited increases in hippocampal microglia and prevented ESI-induced depressive-like behavior as well as increases in IL-1β, IL-6, and TNF-α. Notably, minocycline also triggered downregulation of H3K9me2 expression and restored expression of NR1, GluR1, and GluR2. These results suggest that ESI induces depressive-like behavior, which may be mediated by microglial signaling.

Epigenetic mechanisms involved in modulation of inflammatory diseases

PURPOSE OF REVIEW

The activation of inflammatory response is dependent upon genetic factors and epigenetic control mechanisms. This overview will highlight recent advances in the understanding of epigenetic dynamics during cellular inflammation.

RECENT FINDINGS

There is a growing body of evidence indicating that alterations of the chromatin state associate with an increased risk of chronic disease development and inflammation. Epigenetic alterations respond rapidly to environmental changes and have a profound effect on gene regulatory cross-wirings and transcriptional regulation.

SUMMARY

Systematic dissection of the mechanisms underlying epigenetic effects during inflammatory response is a critical step toward elucidation of the cell's molecular processes and holds potential for the development of novel therapies for the treatment of chronic diseases.

PDX1 and ISL1 differentially coordinate with epigenetic modifications to regulate insulin gene expression in varied glucose concentrations

The mechanism of insulin gene transcription control in response to glucose concentration is poorly defined. The islet-restricted transcription factors PDX1 and ISL1 interact with BETA2, activating insulin gene expression. However, their contribution and hierarchical organization in insulin expression control based on glucose concentration remain unknown. We investigated PDX1 and ISL1 regulation of insulin gene expression in pancreatic β cells cultured in normal (5 mM/L) and high (25 mM/L) glucose conditions. ISL1 interacted with BETA2 to maintain basic insulin gene transcriptional activity under normal glucose. The ISL1-recruited cofactors SET9 and JMJD3 facilitated insulin gene histone modifications under normal glucose. In high-glucose concentrations, PDX1 formed a complex with BETA2 to enhance insulin gene expression. PDX1 also recruited SET9 and JMJD3 to promote the activation of histone modulation on the insulin promoter. This is the first evidence transcription factors orchestrate epigenetic modifications to control insulin gene expression based on glucose concentration.

Increased Expression of SETD7 Promotes Cell Proliferation by Regulating Cell Cycle and Indicates Poor Prognosis in Hepatocellular Carcinoma

Purpose

To investigate the role of SET domain containing 7 (SETD7) in hepatocellular carcinoma (HCC) and determine whether SETD7 can be used as a predictor of overall survival in HCC patients.

Methods

mRNAs and proteins of SETD7 and related genes in HCC tumor samples and paired adjacent non-tumorous liver tissues (ANLTs) (n = 20) or culture cells were determined by quantitative real-time PCR and Western blot. Cell proliferation and apoptosis with SETD7 knockdown SMMC-7721 cells or SETD7 overexpressed HepG2 cells were analyzed by CCK8 assay or flow cytometry. Gene expression alterations in SETD7 knockdown of SMMC-7721 cells were determined by digital gene expression (DGE) profiling. Defined data on patients (n = 225) with HCC were retrieved for the further study. Tissue microarrays (TMAs) were performed using paraffin tissues with tumor and ANLTs. SETD7 and related proteins were determined by TMAs immunohistochemistry. Statistical analyses were conducted to associate SETD7 expression with tumor features and patient outcomes, as well as related proteins expression.

Results

SETD7 expression was significantly higher in HCC tumor tissues than in ANLTs. SETD7 overexpression in vitro can promote HepG2 cell proliferation, whereas SETD7 knockdown can inhibit SMMC-7721 cell proliferation by regulating the cell cycle. SETD7 expression was significantly correlated with five genes expression. Increased SETD7 is associated with metastasis, recurrence, large tumor size, and poor tumor differentiation, and indicates poor prognosis in HCC patients.

Conclusions

SETD7 plays a critical role in HCC, and its immunohistochemistry signature provides potential clinical significance for personalized prediction of HCC prognosis.

SET7/9 inhibits oncogenic activities through regulation of Gli-1 expression in breast cancer

SET7/9 is a protein lysine methyltransferase that had been initially identified as a histone lysine methyltransferase which generates monomethylation at histone 3 lysine 4. Different functions were attributed to the protein methylation mediated by SET7/9. In this study, we found that the expression of SET7/9 declined in a majority of the human breast cancer tissues examined compared with normal tissues. Knockdown of SET7/9 promoted the proliferation, migration, and invasion of breast cancer cells. Knockdown of SET7/9 also increased the tumorigenicity of breast cancer cells in vivo. On the contrary, overexpression of SET7/9 in breast cancer cells inhibited these processes. Microarray analysis indicated that Gli-1 may play function as a downstream factor of SET7/9. Overexpression of SET7/9SET7/9 inhibits Gli-1 expression. While knockdown of SET7/9 promotes the expression of Gli-1. Gli-1 inhibited by cyclopamine blocked knockdown SET7/9-driven proliferation, migration, and invasion in breast cancer cell. Furthermore, Gli-1 expression in human breast cancer tissues is negatively correlated with SET7/9 expression. Together, these results helped to realize the antioncogene functions of SET7/9 in breast cancer cells and provided a novel direction to treat breast cancer.

The TrxG Complex Mediates Cytokine Induced De Novo Enhancer Formation in Islets

To better understand how β-cells respond to proinflammatory cytokines we mapped the locations of histone 3 lysine 4 monomethylation (H3K4me1), a post-translational histone modification enriched at active and poised cis-regulatory regions, in IFNγ, Il-1β, and TNFα treated pancreatic islets. We identified 96,721 putative cis-regulatory loci, of which 3,590 were generated de novo, 3,204 had increased H3K4me1, and 5,354 had decreased H3K4me1 in IFNγ, Il-1β, and TNFα exposed islets. Roughly 10% of the de novo and increased regions were enriched for the repressive histone modification histone 3 lysine 27 trimethylation (H3K27me3) in untreated cells, and these were frequently associated with chemokine genes. We show that IFNγ, Il-1β, and TNFα exposure overcomes this repression and induces chemokine gene activation in as little as three hours, and that this expression persists for days in absence of continued IFNγ, Il-1β, and TNFα exposure. We implicate trithorax group (TrxG) complexes as likely players in the conversion of these repressed loci to an active state. To block the activity of these complexes, we suppressed Wdr5, a core component of the TrxG complexes, and used the H3K27me3 demethylase inhibitor GSK-J4. We show that GSK-J4 is particularly effective in blunting IFNγ, Il-1β, and TNFα-induced chemokine gene expression in β-cells; however, it induced significant islet-cell apoptosis and β-cell dysfunction. Wdr5 suppression also reduced IFNγ, Il-1β, and TNFα induced chemokine gene expression in β-cells without affecting islet-cell survival or β-cell function after 48hrs, but did begin to increase islet-cell apoptosis and β-cell dysfunction after four days of treatment. Taken together these data suggest that the TrxG complex is potentially a viable target for preventing cytokine induced chemokine gene expression in β-cells.