Histone Demethylase JMJD2B Research Articles

Abstract 12879: Endothelial Cu Exporter Atp7a Deficiency Promotes Cu-Dependent Endothelial-to-Mesenchymal Transition and Atherosclerosis via Orchestrating Glycolysis and Ros Signaling

Introduction: Oxidative stress, inflammation and metabolic reprogramming contribute to endothelial cell (EC) dysfunction and atherosclerosis. Copper (Cu), an essential micro-nutrient, promotes atherosclerosis via unknown mechanism. Since excess Cu is toxic, bioavailability of intracellular Cu is tightly controlled by Cu exporter ATP7A. However, the role of ATP7A and its molecular linkage with inflammation, oxidative stress and metabolism in EC dysfunction and atherosclerosis are entirely unknown. Results: Here we found a dramatic reduction of ATP7A expression in human and mouse atherosclerotic aorta. Surprisingly, ATP7A knockdown (KD) in human aortic ECs using shRNA changed the cell morphology from EC to mesenchymal types. This was confirmed by RNAseq/qPCR showing reduced EC markers and increased mesenchymal markers, indicating endothelial to mesenchymal transition (EndMT). Mechanistically, loss of ATP7A in ECs increased [Cu]i and PFKFB3-dependent glycolysis (1.8- fold by ECAR in Seahorse assay). Overexpression of PFKFB3 or constitutively active PFK2, which enhances glycolysis, or direct Cu treatment induced EndMT. In parallel, ATP7A KD in ECs increased mitochondrial (mito)ROS (9.8 fold)-histone demethylase JMJD2B, which induced inflammatory EndMT inducer TGFβ2-EndMT transcription factor Snail (2 fold) axis. Of note, ATP7A KD-induced glycolysis as well as mitoROS- TGFβ2-Snail axis involved in EndMT were inhibited by Cu chelator TTM. In vivo, Cu transport dysfunctional ATP7A mutant/ApoE -/- mice showed enhanced atherosclerosis and CD31 + /αSMA + cells representing EndMT in aorta compared to control ApoE -/- mice, which was further confirmed by EC-specific ATP7A -/- /mTmG reporter mice. Conclusion: Our study demonstrates that ATP7A dysfunction in ECs drives EndMT by orchestrating mitoROS-JMJD2B-TGFβ as well as PFKFB3-glycolysis axis in a Cu dependent manner, leading to Snail induction to accelerates atherosclerosis. Thus, ATP7A is a potential therapeutic target for treatment of inflammatory vascular disease.

The histone demethylase JMJD2B regulates endothelial-to-mesenchymal transition

Endothelial cells play an important role in maintenance of the vascular system and the repair after injury. Under proinflammatory conditions, endothelial cells can acquire a mesenchymal phenotype by a process named endothelial-to-mesenchymal transition (EndMT), which affects the functional properties of endothelial cells. Here, we investigated the epigenetic control of EndMT. We show that the histone demethylase JMJD2B is induced by EndMT-promoting, proinflammatory, and hypoxic conditions. Silencing of JMJD2B reduced TGF-β2-induced expression of mesenchymal genes, prevented the alterations in endothelial morphology and impaired endothelial barrier function. Endothelial-specific deletion of JMJD2B in vivo confirmed a reduction of EndMT after myocardial infarction. EndMT did not affect global H3K9me3 levels but induced a site-specific reduction of repressive H3K9me3 marks at promoters of mesenchymal genes, such as Calponin (CNN1), and genes involved in TGF-β signaling, such as AKT Serine/Threonine Kinase 3 (AKT3) and Sulfatase 1 (SULF1). Silencing of JMJD2B prevented the EndMT-induced reduction of H3K9me3 marks at these promotors and further repressed these EndMT-related genes. Our study reveals that endothelial identity and function is critically controlled by the histone demethylase JMJD2B, which is induced by EndMT-promoting, proinflammatory, and hypoxic conditions, and supports the acquirement of a mesenchymal phenotype.

Histone H3K9 demethylase JMJD2B induces hepatic steatosis through upregulation of PPAR\u03b32

Understanding the epigenetic mechanisms underlying the progression of hepatic steatosis is important for identifying new therapeutic targets against nonalcoholic fatty liver disease (NAFLD). We investigated the functional role of histone demethylase JMJD2B in the pathologic regulation of hepatic steatosis. JMJD2B expression was markedly increased in HepG2 cells treated with palmitate and oleate or liver X receptor agonist T09013178 and in the liver of high-fat diet (HFD)-induced obese mice. Overexpression of JMJD2B using adenovirus in HepG2 cells stimulated the expression of peroxisome proliferator-activated receptor γ2 (PPARγ2) and its steatosis target genes associated with fatty acid uptake and lipid droplet formation, resulting in increased intracellular triglyceride (TG) accumulation. Conversely, knocking down JMJD2B using siRNA reversed JMJD2B-mediated effects in HepG2 cells. The JMJD2B-dependent upregulation of PPARγ2 was associated with the removal of di- and trimethylation of histone H3 lysine 9 on the promoter of PPARγ2. Furthermore, exogeneous expression of JMJD2B using adenovirus in mice resulted in hepatic steatosis when fed a HFD, which was accompanied with increased expression of hepatic PPARγ2 and its steatosis target genes. Together, our results provide novel insights into the pivotal role of JMJD2B in the development of hepatic steatosis through upregulation of PPARγ2 and steatosis target genes.

Dehydroleucodine inhibits mitotic clonal expansion during adipogenesis through cell cycle arrest.

Aberrant levels of preadipocyte differentiation, triggered by adipocyte hyperplasia and hypertrophy, results in the obesogenic phenotype. Obesity is a risk factor for several metabolic disorders. In this paper, dehydroleucodine inhibited the accumulation of lipid droplets and decreased the elevations of triglycerides, and this inhibitory effect occurred during the early stage of adipogenesis. Thus, not only did dehydroleucodine downregulate the expression of C/EBPα and PPARγ, it also strongly blocked the expression of C/EBPβ, an early stage biomarker of early adipogenesis, in a concentration-dependent manner. The proliferation of preadipocytes was dramatically suppressed when dehydroleucodine was added to the medium as early as 24hr. These results indicate that dehydroleucodine may specifically affect mitotic clonal expansion to inhibit preadipocyte differentiation. Dehydroleucodine arrested the cell cycle at the G0 /G1 phase, increased p27 and decreased both cyclins A and D and their partners (e.g., CDK2 and CDK4). Additionally, dehydroleucodine decreased phosphorylation of Erk1/2 and Akt. Furthermore, dehydroleucodine downregulated expression of histone demethylase JMJD2B as well as repressed the expression of histone methyltransferase MLL4, which in turn diminished the expression of C/EBPβ and PPARγ, respectively. Collectively, our results indicate that dehydroleucodine inhibits preadipocyte differentiation by blocking mitotic clonal expansion via cell cycle arrest, which may be mediated by regulation of selective histone methylation/demethylation in transcription activation during the early step of adipogenesis.

MiR-491-5p functions as a tumor suppressor by targeting JMJD2B in ERα-positive breast cancer

The involvement of miR-491-5p in breast cancer development is unclear. This study showed that miR-491-5p is significantly downregulated in ERα-positive breast cancer tissues and cell lines and is generally hypermethylated in ERα-positive breast cancer. MiR-491-5p overexpression significantly suppressed estrogen signaling and estrogen-stimulated proliferation of breast cancer cells. Furthermore, the histone demethylase JMJD2B was identified as a direct target of miR-491-5p. The ectopic expression of JMJD2B abrogated the phenotypic changes induced by miR-491-5p in breast cancer cells. Collectively, our data indicate that miR-491-5p plays a tumor suppressor role in the development and progression of breast caner and may be a novel therapeutic target against ERα-positive breast cancer.

The histone demethylase JMJD2B is associated with recurrent pregnancy loss and promotes decidualization of endometrial stromal cells

The histone demethylase JMJD2B is associated with recurrent pregnancy loss and promotes decidualization of endometrial stromal cells

Functional Analysis of Histone Demethylase Jmjd2b on Lipopolysaccharide-Treated Murine Neural Stem Cells (NSCs)

Neural stem cell (NSC) neurogenesis is the formation of new neurons by which the brain maintains its lifelong plasticity in response to extrinsic and intrinsic changes. Here, we show the effect of lipopolysaccharides (LPS) as an in vitro model of inflammation on NSCs to determine whether the inflammatory mediators can epigenetically affect NSCs and alter their proliferation and differentiation abilities. To study the effect of LPS on NSCs, we used an immortalized mouse neuroectodermal stem cell line, NE-4C. We found that Jmjd2b, histone-3 lysine-9 di-/tri-methyl (H3K9me2/3) demethylase, is functional following LPS treatment and is crucial in multiple signaling pathways and biological processes. The global gene expression levels were detected in Jmjd2b-knockdown (kd) NE-4C cells and in LPS-stimulated Jmjd2b-kd NE-4C cells using an Affymetrix GeneChip(®) Mouse Gene 1.0 ST Array. In addition, the datasets were analyzed using MetaCore Pathway Analysis (GeneGo). The attenuation of Jmjd2b in NE-4C cells significantly affected the p65, iNOS, Bcl2, and TGF-β expression levels and had downstream effects on related signaling pathways. In addition, chromatin immunoprecipitation revealed that Jmjd2b-kd could inhibit the Notch1, IL-1β, and IL-2 genes by recruiting repressive H3K9me3 to their promoters. Moreover, this study highlights Jmjd2b role in LPS-mediated inflammation, which suggests an epigenetic regulation in NE-4C cells. Finally, this study establishes novel Jmjd2b targets that potentiate a biological rationale involving Jmjd2b in NSC inflammation.

HIF-1α-induced histone demethylase JMJD2B contributes to the malignant phenotype of colorectal cancer cells via an epigenetic mechanism

Hypoxia-inducible factor 1α (HIF-1α) plays a key role in mediating cancer cell malignant characteristics. Recent studies have shown that the histone demethylase JMJD2B is a target of HIF-1α, suggesting that histone methylation may be involved in tumor malignancy during hypoxia. However, little is known about the tumorigenic role of JMJD2B and its association with hypoxia in colorectal cancer (CRC). Furthermore, the downstream target genes and the mechanisms by which JMJD2B regulates its target genes in CRC during hypoxia remain to be clarified. Our results demonstrated that JMJD2B was induced under hypoxia in an HIF-1α-dependent manner in CRC cells. JMJD2B played an important role in CRC cell proliferation, apoptosis, cell cycle arrest and invasion, which could be modulated through upregulation of a subset of hypoxia-inducible genes expression by decreasing trimethylation of histone H3 lysine 9 on their promoters. We also showed that JMJD2B was overexpressed in CRC tissues and positively correlated with expression of the hypoxic marker carbonic anhydrase 9 (CA9), deeper depth of invasion and advanced clinical stages. Therefore, our findings suggest that JMJD2B may serve as a potential therapeutic cancer target.

The Histone Demethylase JMJD2B Plays an Essential Role in Human Carcinogenesis through Positive Regulation of Cyclin-Dependent Kinase 6

Histone methyltransferases and demethylases are known to regulate transcription by altering the epigenetic marks on histones, but the pathologic roles of their dysfunction in human diseases, such as cancer, still remain to be elucidated. Herein, we show that the histone demethylase JMJD2B is involved in human carcinogenesis. Quantitative real-time PCR showed notably elevated levels of JMJD2B expression in bladder cancers, compared with corresponding nonneoplastic tissues (P < 0.0001), and elevated protein expression was confirmed by immunohistochemistry. In addition, cDNA microarray analysis revealed transactivation of JMJD2B in lung cancer, and immunohistochemical analysis showed protein overexpression in lung cancer. siRNA-mediated reduction of expression of JMJD2B in bladder and lung cancer cell lines significantly suppressed the proliferation of cancer cells, and suppressing JMJD2B expression lead to a decreased population of cancer cells in S phase, with a concomitant increase of cells in G(1) phase. Furthermore, a clonogenicity assay showed that the demethylase activity of JMJD2B possesses an oncogenic activity. Microarray analysis after knockdown of JMJD2B revealed that JMJD2B could regulate multiple pathways which contribute to carcinogenesis, including the cell-cycle pathway. Of the downstream genes, chromatin immunoprecipitation showed that CDK6 (cyclin-dependent kinase 6), essential in G(1)-S transition, was directly regulated by JMJD2B, via demethylation of histone H3-K9 in its promoter region. Expression levels of JMJD2B and CDK6 were significantly correlated in various types of cell lines. Deregulation of histone demethylation resulting in perturbation of the cell cycle, represents a novel mechanism for human carcinogenesis and JMJD2B is a feasible molecular target for anticancer therapy.

Histone demethylase JMJD2B coordinates H3K4/H3K9 methylation and promotes hormonally responsive breast carcinogenesis

It is well-documented that the methylation of histone H3 lysine 4 (H3K4) and of H3K9 are mutually exclusive, an epigenetic phenomenon conserved from yeast to humans. How this opposed methylation modification is accomplished and coordinated in mammalian cells is poorly understood. Here we report that the H3K9 trimethyl demethylase JMJD2B is an integral component of the H3K4-specific methyltransferase, the mixed-lineage leukemia (MLL) 2 complex. We show that the JMJD2B/MLL2 complex is copurified with estrogen receptor α (ERα) and is required for ERα-regulated transcription. We demonstrate that H3K9 demethylation and H3K4 methylation are coordinated in ERα-activated transcription such that H3K9 demethylation is a prerequisite for H3K4 methylation. Significantly, depletion of JMJD2B impairs the estrogen-induced G(1)/S transition of the cell cycle in vitro and inhibits breast tumorigenesis in vivo. Interestingly, JMJD2B itself is an ERα target gene, and forms a feed-forward regulatory loop in regulation of the hormone response. Our results provide a molecular basis for the coordinated H3K4 methylation/H3K9 demethylation in transcription activation, link the trimethyl demethylase JMJD2B to euchromatin functions, and provide a mechanism for JMJD2B in breast carcinogenesis.

Histone demethylase JMJD2B functions as a co-factor of estrogen receptor in breast cancer proliferation and mammary gland development.

Estrogen is a key regulator of normal function of female reproductive system and plays a pivotal role in the development and progression of breast cancer. Here, we demonstrate that JMJD2B (also known as KDM4B) constitutes a key component of the estrogen signaling pathway. JMJD2B is expressed in a high proportion of human breast tumors, and that expression levels significantly correlate with estrogen receptor (ER) positivity. In addition, 17-beta-estradiol (E2) induces JMJD2B expression in an ERα dependent manner. JMJD2B interacts with ERα and components of the SWI/SNF-B chromatin remodeling complex. JMJD2B is recruited to ERα target sites, demethylates H3K9me3 and facilitates transcription of ER responsive genes including MYB, MYC and CCND1. As a consequence, knockdown of JMJD2B severely impairs estrogen-induced cell proliferation and the tumor formation capacity of breast cancer cells. Furthermore, Jmjd2b-deletion in mammary epithelial cells exhibits delayed mammary gland development in female mice. Taken together, these findings suggest an essential role for JMJD2B in the estrogen signaling, and identify JMJD2B as a potential therapeutic target in breast cancer.

The Histone Demethylase JMJD2B Is Regulated by Estrogen Receptor α and Hypoxia, and Is a Key Mediator of Estrogen Induced Growth

Estrogen receptor alpha (ERalpha) plays an important role in breast cancer. Upregulation of HIF-1alpha in ER(alpha)-positive cancers suggests that HIF-1alpha may cooperate with ERalpha to promote breast cancer progression and consequently affect breast cancer treatment. Here, we show the histone demethylase JMJD2B is regulated by both ERalpha and HIF-1alpha, drives breast cancer cell proliferation in normoxia and hypoxia, and epigenetically regulates the expression of cell cycle genes such as CCND1, CCNA1, and WEE1. We also show that JMJD2B and the hypoxia marker CA9 together stratify a subclass of breast cancer patients and predict a worse outcome of these breast cancers. Our findings provide a biological rationale to support the therapeutic targeting of histone demethylases in breast cancer patients.

Abstract 1818: Wnt5a Increases the Histone Demethylase Jmjd2b and Induces Epigenetic Remodelling in Adult Progenitor Cells

Wnt signalling controls the balance between stem cell proliferation and differentiation and patterning throughout development. Non-canonical Wnts, such as Wnt5a or Wnt11, enhance cardiac gene expression of endothelial progenitor cells (EPC), mesenchymal stem cells (MSC) and bone marrow mononuclear cells suggesting that non-canonical Wnts regulate cardiac commitment. However, the underlying mechanism is unclear. Using microarray analysis of Wnt5a-induced gene expression in EPC, we discovered that Wnt5a (1.0 μM, 24hours) significantly increased a variety of enzymes, which play key roles in epigenetic remodelling by modifying histone acetylation and methylation. Specifically, JMJD2B (205%), REST (311%), HDAC5 and HDAC7A (716 and 381%), YY1 (304%), and PCGF2 (352%), were significantly increased by Wnt5a. Wnt5a induced up-regulation of JMJD2B in EPC and MSC was further confirmed by real-time RT-PCR. The member of the JmjC-domain containing family, JMJD2B was recently shown to demethylate trimethylated histone H3 at lysine 9 (H3K9me3), thereby removing repressive histone modifications. Therefore, we hypothesized that increased JMJD2B might epigenetically modify gene expression, open chromatin structures at silenced promoters and modulate the differentiation of adult progenitor cells. Indeed, Wnt5a treatment reduced the repressive chromatin mark H3K9me3 as shown by Western blot and immunohistochemistry whereas global active chromatine marks (acetyl-H3 and trimethyl- H3K4) remained unchanged indicating that Wnt5a shifts the balance towards active gene expression. Furthermore, chromatin immunoprecipitation revealed that Wnt5a treatment increased the binding of JMJD2B at the promoter of the cardiac gene ANF. In line with removal of repressive chromatin marks, Wnt5a significantly increased differentiation of progenitor cells to cardiomyocytes. These data demonstrate that non-canonical Wnt5a induces epigenetic remodelling by removing repressive chromatin marks and may, thereby, sensitize adult progenitor cells for acquiring a cardiac cell fate. Further studies will investigate the specific contribution of the novel epigenetic modulator JMJD2B for adult stem cell functions.