scholarly journals Histone Demethylase UTX Compromises Articular Chondrocyte Anabolism and Aggravates Osteoarthritic Degeneration

2021 ◽  
Author(s):  
Wei-Shiung Lian ◽  
Re-Wen Wu ◽  
Jih-Yang Ko ◽  
Yu-Shan Chen ◽  
Shao-Yu Wang ◽  
...  
Keyword(s):  
Articular Chondrocytes ◽  
Cartilage Degeneration ◽  
Histone Demethylase ◽  
Loss Of Function ◽  
Articular Chondrocyte ◽  
Polycomb Repressive Complex 2 ◽  
Tissue Integrity ◽  
Histone 3 ◽  
Core Components ◽  
Cartilage Erosion

Abstract Histone demethylase UTX removes repressive trimethyl groups at lysine 27 of histone 3 (H3K27me3) to regulate tissue integrity, while its role was not yet studied in articulating joint tissues in situ. We now found that UTX expression in articular chondrocytes positively correlated with human osteoarthritis. Utx overexpression induced chondrocyte dysfunction, cartilage degeneration and osteophyte induction in mice. In contrast, chondrocyte-specific Utx knockout in mice promoted gross articular morphology and delayed age- and collagenase-induced cartilage erosion, synovitis and osteophyte formation and largely eliminated disease-associated joint pain. Additionally, pharmacological inhibition of Utx through GSK-J4 preserved cartilage integrity. Our study is the first to suggest that Utx loss-mediated cartilage protection involved a dysregulation of polycomb repressive complex 2 core components EZH2, EED, and SUZ12 to induce H3K27 hypomethylation and a net anabolic effect. Specifically, Utx loss-of-function appears to involve, among others, Wnt10a signaling to reduce chondrocytic activities and an IGF-2-mediated stimulation of extracellular matrix synthesis.

scholarly journals EZH2 is essential for fate determination in the mammalian Isthmic area

2018 ◽  
Author(s):  
Iris Wever ◽  
Cindy M.R.J. Wagemans ◽  
Marten P. Smidt
Keyword(s):  
Gene Silencing ◽  
Dopaminergic Neurons ◽  
Neuronal Development ◽  
Polycomb Group ◽  
Loss Of Function ◽  
Developmental Transitions ◽  
Neuronal Progenitor ◽  
Histone 3 ◽  
Conditional Mutant ◽  
Core Components

AbstractThe polycomb group proteins (PcGs) are a group of epigenetic factors associated with gene silencing. They are found in several families of multiprotein complexes, including Polycomb Repressive Complex (PRC) 2. EZH2, EED and SUZ12 form the core components of the PRC2 complex, which is responsible for the mono, di- and trimethylation of lysine 27 of histone 3 (H3K27Me3), the chromatin mark associated with gene silencing. Loss-of-function studies of Ezh2, the catalytic subunit of PRC2, have shown that PRC2 plays a role in regulating developmental transitions of neuronal progenitor cells; from self-renewal to differentiation and the neurogenic-to-gliogenic fate switch.To further address the function of EZH2 and H3K27me3 during neuronal development we generated a conditional mutant in which Ezh2 was removed in the mammalian isthmic (mid-hindbrain) region from E10.5 onward. Loss of Ezh2 changed the molecular coding of the anterior ventral hindbrain leading to a fate switch and the appearance of ectopic dopaminergic neurons. The correct specification of the isthmic region is dependent on the signaling factors produced by the Isthmic organizer (IsO), located at the border of the mid- and hindbrain. We propose that the change of cellular fate is a result of the presence of Otx2 in the hindbrain of Ezh2 conditional knock-outs and a dysfunctional IsO, as represented by the loss of Fgf8 and Wnt1. Our work implies that next to controlling developmental transitions, EZH2 mediated gene silencing is important for specification of the isthmic region by influencing IsO functioning and repressing Otx2 in the hindbrain.

scholarly journals Peritoneal Modulators of EZH2-miR-155 Cross-Talk in Endometriosis

2021 ◽  
Vol 22 (7) ◽  
pp. 3492
Author(s):  
Sarah Brunty ◽  
Kristeena Ray Wright ◽  
Brenda Mitchell ◽  
Nalini Santanam
Keyword(s):  
Differential Expression ◽  
Cross Talk ◽  
Chromatin Immunoprecipitation ◽  
Peritoneal Fluid ◽  
Loss Of Function ◽  
Polycomb Repressive Complex ◽  
Polycomb Repressive Complex 2 ◽  
Histone 3 ◽  
Binding Partners ◽  
Complex Components

Activation of trimethylation of histone 3 lysine 27 (H3K27me3) by EZH2, a component of the Polycomb repressive complex 2 (PRC2), is suggested to play a role in endometriosis. However, the mechanism by which this complex is dysregulated in endometriosis is not completely understood. Here, using eutopic and ectopic tissues, as well as peritoneal fluid (PF) from IRB-approved and consented patients with and without endometriosis, the expression of PRC2 complex components, JARID2, miR-155 (known regulators of EZH2), and a key inflammatory modulator, FOXP3, was measured. A higher expression of EZH2, H3K27me3, JARID2, and FOXP3 as well as miR-155 was noted in both the patient tissues and in endometrial PF treated cells. Gain-or-loss of function of miR-155 showed an effect on the PRC2 complex but had little effect on JARID2 expression, suggesting alternate pathways. Chromatin immunoprecipitation followed by qPCR showed differential expression of PRC2 complex proteins and its associated binding partners in JARID2 vs. EZH2 pull down assays. In particular, endometriotic PF treatment increased the expression of PHF19 (p = 0.0474), a gene silencer and co-factor that promotes PRC2 interaction with its targets. Thus, these studies have identified the potential novel crosstalk between miR-155-PRC2 complex-JARID2 and PHF19 in endometriosis, providing an opportunity to test other epigenetic targets in endometriosis.

scholarly journals Calcium Input Potentiates the Transforming Growth Factor (TGF)-β1-dependent Signaling to Promote the Export of Inorganic Pyrophosphate by Articular Chondrocyte

2011 ◽  
Vol 286 (22) ◽  
pp. 19215-19228 ◽  
Author(s):  
Frederic Cailotto ◽  
Pascal Reboul ◽  
Sylvie Sebillaud ◽  
Patrick Netter ◽  
Jean-Yves Jouzeau ◽  
...  
Keyword(s):  
Growth Factor ◽  
Promoter Activity ◽  
Transforming Growth Factor ◽  
Articular Chondrocytes ◽  
Specific Protein ◽  
Dependent Manner ◽  
Articular Chondrocyte ◽  
Experimental Conditions ◽  
Inorganic Pyrophosphate ◽  
Tgf Β1

Transforming growth factor (TGF)-β1 stimulates extracellular PPi (ePPi) generation and promotes chondrocalcinosis, which also occurs secondary to hyperparathyroidism-induced hypercalcemia. We previously demonstrated that ANK was up-regulated by TGF-β1 activation of ERK1/2 and Ca2+-dependent protein kinase C (PKCα). Thus, we investigated mechanisms by which calcium could affect ePPi metabolism, especially its main regulating proteins ANK and PC-1 (plasma cell membrane glycoprotein-1). We stimulated articular chondrocytes with TGF-β1 under extracellular (eCa2+) or cytosolic Ca2+ (cCa2+) modulations. We studied ANK, PC-1 expression (quantitative RT-PCR, Western blotting), ePPi levels (radiometric assay), and cCa2+ input (fluorescent probe). Voltage-operated Ca2+-channels (VOC) and signaling pathways involved were investigated with selective inhibitors. Finally, Ank promoter activity was evaluated (gene reporter). TGF-β1 elevated cCa2+ and ePPi levels (by up-regulating Ank and PC-1 mRNA/proteins) in an eCa2+ dose-dependent manner. TGF-β1 effects were suppressed by cCa2+ chelation or L- and T-VOC blockade while being mostly reproduced by ionomycin. In the same experimental conditions, the activation of Ras, the phosphorylation of ERK1/2 and PKCα, and the stimulation of Ank promoter activity were affected similarly. Activation of SP1 (specific protein 1) and ELK-1 (Ets-like protein-1) transcription factors supported the regulatory role of Ca2+. SP1 or ELK-1 overexpression or blockade experiments demonstrated a major contribution of ELK-1, which acted synergistically with SP1 to activate Ank promoter in response to TGF-β1. TGF-β1 promotes input of eCa2+ through opening of L- and T-VOCs, to potentiate ERK1/2 and PKCα signaling cascades, resulting in an enhanced activation of Ank promoter and ePPi production in chondrocyte.

scholarly journals The loss of Ezh2 drives the pathogenesis of myelofibrosis and sensitizes tumor-initiating cells to bromodomain inhibition

2016 ◽  
Vol 213 (8) ◽  
pp. 1459-1477 ◽  
Author(s):  
Goro Sashida ◽  
Changshan Wang ◽  
Takahisa Tomioka ◽  
Motohiko Oshima ◽  
Kazumasa Aoyama ◽  
...  
Keyword(s):  
Target Genes ◽  
Myeloproliferative Neoplasms ◽  
Primary Myelofibrosis ◽  
Loss Of Function ◽  
Tumor Initiating Cells ◽  
Promoter Regions ◽  
Epigenetic Switch ◽  
Polycomb Repressive Complex 2 ◽  
Conditional Deletion ◽  
Activating Mutation

EZH2 is a component of polycomb repressive complex 2 (PRC2) and functions as an H3K27 methyltransferase. Loss-of-function mutations in EZH2 are associated with poorer outcomes in patients with myeloproliferative neoplasms (MPNs), particularly those with primary myelofibrosis (MF [PMF]). To determine how EZH2 insufficiency is involved in the pathogenesis of PMF, we generated mice compound for an Ezh2 conditional deletion and activating mutation in JAK2 (JAK2V617F) present in patients with PMF. The deletion of Ezh2 in JAK2V617F mice markedly promoted the development of MF, indicating a tumor suppressor function for EZH2 in PMF. The loss of Ezh2 in JAK2V617F hematopoietic cells caused significant reductions in H3K27 trimethylation (H3K27me3) levels, resulting in an epigenetic switch to H3K27 acetylation (H3K27ac). These epigenetic switches were closely associated with the activation of PRC2 target genes including Hmga2, an oncogene implicated in the pathogenesis of PMF. The treatment of JAK2V617F/Ezh2-null mice with a bromodomain inhibitor significantly attenuated H3K27ac levels at the promoter regions of PRC2 targets and down-regulated their expression, leading to the abrogation of MF-initiating cells. Therefore, an EZH2 insufficiency not only cooperated with active JAK2 to induce MF, but also conferred an oncogenic addiction to the H3K27ac modification in MF-initiating cells that was capable of being restored by bromodomain inhibition.

scholarly journals Autochthonous tumors driven by Rb1 loss have an ongoing requirement for the RBP2 histone demethylase

2018 ◽  
Vol 115 (16) ◽  
pp. E3741-E3748 ◽  
Author(s):  
Samuel K. McBrayer ◽  
Benjamin A. Olenchock ◽  
Gabriel J. DiNatale ◽  
Diana D. Shi ◽  
Januka Khanal ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
Histone Demethylase ◽  
Retinoblastoma Gene ◽  
Loss Of Function ◽  
Genetic Ablation ◽  
Tumor Bearing ◽  
Human Cancers ◽  
Promising Strategy ◽  
Downstream Effectors ◽  
Slow Tumor Growth

Inactivation of the retinoblastoma gene (RB1) product, pRB, is common in many human cancers. Targeting downstream effectors of pRB that are central to tumorigenesis is a promising strategy to block the growth of tumors harboring loss-of-function RB1 mutations. One such effector is retinoblastoma-binding protein 2 (RBP2, also called JARID1A or KDM5A), which encodes an H3K4 demethylase. Binding of pRB to RBP2 has been linked to the ability of pRB to promote senescence and differentiation. Importantly, genetic ablation of RBP2 is sufficient to phenocopy pRB’s ability to induce these cellular changes in cell culture experiments. Moreover, germline Rbp2 deletion significantly impedes tumorigenesis in Rb1+/− mice. The value of RBP2 as a therapeutic target in cancer, however, hinges on whether loss of RBP2 could block the growth of established tumors as opposed to simply delaying their onset. Here we show that conditional, systemic ablation of RBP2 in tumor-bearing Rb1+/− mice is sufficient to slow tumor growth and significantly extend survival without causing obvious toxicity to the host. These findings show that established Rb1-null tumors require RBP2 for growth and further credential RBP2 as a therapeutic target in human cancers driven by RB1 inactivation.

scholarly journals GSK5182, 4-Hydroxytamoxifen Analog, a New Potential Therapeutic Drug for Osteoarthritis

2020 ◽  
Vol 13 (12) ◽  
pp. 429
Author(s):  
Yunhui Min ◽  
Dahye Kim ◽  
Godagama Gamaarachchige Dinesh Suminda ◽  
Xiangyu Zhao ◽  
Mangeun Kim ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Small Molecule ◽  
Articular Chondrocytes ◽  
Therapeutic Potential ◽  
Inverse Agonist ◽  
Therapeutic Drug ◽  
Articular Chondrocyte ◽  
Orphan Nuclear Receptors ◽  
Genetic Ablation ◽  
Pro Inflammatory Cytokines

Estrogen-related receptors (ERRs) are the first identified orphan nuclear receptors. The ERR family consists of ERRα, ERRβ, and ERRγ, regulating diverse isoform-specific functions. We have reported the importance of ERRγ in osteoarthritis (OA) pathogenesis. However, therapeutic approaches with ERRγ against OA associated with inflammatory mechanisms remain limited. Herein, we examined the therapeutic potential of a small-molecule ERRγ inverse agonist, GSK5182 (4-hydroxytamoxifen analog), in OA, to assess the relationship between ERRγ expression and pro-inflammatory cytokines in mouse articular chondrocyte cultures. ERRγ expression increased following chondrocyte exposure to various pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. Pro-inflammatory cytokines dose-dependently increased ERRγ protein levels. In mouse articular chondrocytes, adenovirus-mediated ERRγ overexpression upregulated matrix metalloproteinase (MMP)-3 and MMP-13, which participate in cartilage destruction during OA. Adenovirus-mediated ERRγ overexpression in mouse knee joints or ERRγ transgenic mice resulted in OA. In mouse joint tissues, genetic ablation of Esrrg obscured experimental OA. These results indicate that ERRγ is involved in OA pathogenesis. In mouse articular chondrocytes, GSK5182 inhibited pro-inflammatory cytokine-induced catabolic factors. Consistent with the in vitro results, GSK5182 significantly reduced cartilage degeneration in ERRγ-overexpressing mice administered intra-articular Ad-Esrrg. Overall, the ERRγ inverse agonist GSK5182 represents a promising therapeutic small molecule for OA.

scholarly journals Epigenetic reprogramming and chromatin accessibility in pediatric diffuse intrinsic pontine gliomas: a neural developmental disease

2019 ◽  
Vol 22 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Flor M Mendez ◽  
Felipe J Núñez ◽  
Maria B Garcia-Fabiani ◽  
Santiago Haase ◽  
Stephen Carney ◽  
...  
Keyword(s):  
Histone Variants ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Chromatin Accessibility ◽  
Therapeutic Implications ◽  
Polycomb Repressive Complex 2 ◽  
K27m Mutation ◽  
Histone 3 ◽  
Epigenetic Programming ◽  
Genes Encoding ◽  
Diffuse Intrinsic Pontine Gliomas

Abstract Diffuse intrinsic pontine glioma (DIPG) is a rare but deadly pediatric brainstem tumor. To date, there is no effective therapy for DIPG. Transcriptomic analyses have revealed DIPGs have a distinct profile from other pediatric high-grade gliomas occurring in the cerebral hemispheres. These unique genomic characteristics coupled with the younger median age group suggest that DIPG has a developmental origin. The most frequent mutation in DIPG is a lysine to methionine (K27M) mutation that occurs on H3F3A and HIST1H3B/C, genes encoding histone variants. The K27M mutation disrupts methylation by polycomb repressive complex 2 on histone H3 at lysine 27, leading to global hypomethylation. Histone 3 lysine 27 trimethylation is an important developmental regulator controlling gene expression. This review discusses the developmental and epigenetic mechanisms driving disease progression in DIPG, as well as the profound therapeutic implications of epigenetic programming.

scholarly journals High-Throughput Identification of MiR-145 Targets in Human Articular Chondrocytes

Life ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 58
Author(s):  
Aida Martinez-Sanchez ◽  
Stefano Lazzarano ◽  
Eshita Sharma ◽  
Helen Lockstone ◽  
Christopher L. Murphy
Keyword(s):  
Cartilage Repair ◽  
High Throughput ◽  
High Throughput Sequencing ◽  
Articular Chondrocytes ◽  
Articular Chondrocyte ◽  
Coding Region ◽  
Cartilage Development ◽  
Rna Immunoprecipitation ◽  
Important Regulator ◽  
Mmp13 Expression

MicroRNAs (miRNAs) play key roles in cartilage development and homeostasis and are dysregulated in osteoarthritis. MiR-145 modulation induces profound changes in the human articular chondrocyte (HAC) phenotype, partially through direct repression of SOX9. Since miRNAs can simultaneously silence multiple targets, we aimed to identify the whole targetome of miR-145 in HACs, critical if miR-145 is to be considered a target for cartilage repair. We performed RIP-seq (RNA-immunoprecipitation and high-throughput sequencing) of miRISC (miRNA-induced silencing complex) in HACs overexpressing miR-145 to identify miR-145 direct targets and used cWords to assess enrichment of miR-145 seed matches in the identified targets. Further validations were performed by RT-qPCR, Western immunoblot, and luciferase assays. MiR-145 affects the expression of over 350 genes and directly targets more than 50 mRNAs through the 3′UTR or, more commonly, the coding region. MiR-145 targets DUSP6, involved in cartilage organization and development, at the translational level. DUSP6 depletion leads to MMP13 upregulation, suggesting a contribution towards the effect of miR-145 on MMP13 expression. In conclusion, miR-145 directly targets several genes involved in the expression of the extracellular matrix and inflammation in primary chondrocytes. Thus, we propose miR-145 as an important regulator of chondrocyte function and a new target for cartilage repair.

EZH2 function in immune cell development

2020 ◽  
Vol 401 (8) ◽  
pp. 933-943 ◽  
Author(s):  
Stephen L. Nutt ◽  
Christine Keenan ◽  
Michaël Chopin ◽  
Rhys S. Allan
Keyword(s):  
Immune System ◽  
Cell Function ◽  
Immune Cell ◽  
Proliferating Cells ◽  
Hematopoietic Stem ◽  
Polycomb Repressive Complex 2 ◽  
Current State ◽  
Core Components ◽  
And Function ◽  
Cell Cycle Inhibitors

AbstractThe polycomb repressive complex 2 (PRC2) consists of three core components EZH2, SUZ12 and EED. EZH2 catalyzes the methylation of lysine 27 of histone H3, a modification associated with gene silencing. Through gene duplication higher vertebrate genomes also encode a second partially redundant methyltransferase, EZH1. Within the mammalian immune system most research has concentrated on EZH2 which is expressed predominantly in proliferating cells. EZH2 and other PRC2 components are required for hematopoietic stem cell function and lymphocyte development, at least in part by repressing cell cycle inhibitors. At later stages of immune cell differentiation, EZH2 plays essential roles in humoral and cell-mediated adaptive immunity, as well as the maintenance of immune homeostasis. EZH2 is often overactive in cancers, through both gain-of-function mutations and over-expression, an observation that has led to the development and clinical testing of specific EZH2 inhibitors. Such inhibitors may also be of use in inflammatory and autoimmune settings, as EZH2 inhibition dampens the immune response. Here, we will review the current state of understanding of the roles for EZH2, and PRC2 more generally, in the development and function of the immune system.

scholarly journals Mesenchymal stem cell-derived exosomal microRNA-136-5p inhibits chondrocyte degeneration in traumatic osteoarthritis by targeting ELF3

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Xue Chen ◽  
Yuanyuan Shi ◽  
Pan Xue ◽  
Xinli Ma ◽  
Junfeng Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Mouse Model ◽  
Cartilage Degeneration ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Post Traumatic ◽  
Chondrocyte Migration

Abstract Background Emerging evidence suggests that microRNAs (miRs) are associated with the progression of osteoarthritis (OA). In this study, the role of exosomal miR-136-5p derived from mesenchymal stem cells (MSCs) in OA progression is investigated and the potential therapeutic mechanism explored. Methods Bone marrow mesenchymal stem cells (BMMSCs) and their exosomes were isolated from patients and identified. The endocytosis of chondrocytes and the effects of exosome miR-136-5p on cartilage degradation were observed and examined by immunofluorescence and cartilage staining. Then, the targeting relationship between miR-136-5p and E74-like factor 3 (ELF3) was analyzed by dual-luciferase report assay. Based on gain- or loss-of-function experiments, the effects of exosomes and exosomal miR-136-5p on chondrocyte migration were examined by EdU and Transwell assay. Finally, a mouse model of post-traumatic OA was developed to evaluate effects of miR-136-5p on chondrocyte degeneration in vivo. Results In the clinical samples of traumatic OA cartilage tissues, we detected increased ELF3 expression, and reduced miR-136-5p expression was determined. The BMMSC-derived exosomes showed an enriched level of miR-136-5p, which could be internalized by chondrocytes. The migration of chondrocyte was promoted by miR-136-5p, while collagen II, aggrecan, and SOX9 expression was increased and MMP-13 expression was reduced. miR-136-5p was verified to target ELF3 and could downregulate its expression. Moreover, the expression of ELF3 was reduced in chondrocytes after internalization of exosomes. In the mouse model of post-traumatic OA, exosomal miR-136-5p was found to reduce the degeneration of cartilage extracellular matrix. Conclusion These data provide evidence that BMMSC-derived exosomal miR-136-5p could promote chondrocyte migration in vitro and inhibit cartilage degeneration in vivo, thereby inhibiting OA pathology, which highlighted the transfer of exosomal miR-136-5p as a promising therapeutic strategy for patients with OA.

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