Chronic corticosterone exposure in rats induces sex-specific alterations in hypothalamic reelin fragments, MeCP2, and DNMT3a protein levels

Women are disproportionately affected by stress-related disorders like depression. In our prior research, we discovered that females exhibit lower basal hypothalamic reelin levels, and these levels are differentially influenced by chronic stress induced through repeated corticosterone (CORT) injections. Although epigenetic mechanisms involving DNA methylation and the formation of repressor complexes by DNA methyl-transferases (DNMTs) and Methyl-CpG binding protein 2 (MeCP2) have been recognized as regulators of reelin expression in vitro, there is limited understanding of the impact of stress on the epigenetic regulation of reelin in vivo and whether sex differences exist in these mechanisms. To address these questions, we conducted various biochemical analyses on hypothalamic brain samples obtained from male and female rats previously treated with either 21 days of CORT (40 mg/kg) or vehicle (0.9 % saline) subcutaneous injections. Upon chronic CORT treatment, a reduction in reelin fragment NR2 was noted in males, while the full-length molecule remained unaffected. This decrease paralleled with an elevation in MeCP2 and a reduction in DNMT3a protein levels only in males. Importantly, sex differences in baseline and CORT-induced reelin protein levels were not associated with changes in the methylation status of the Reln promoter. These findings suggest that CORT-induced reelin decreases in the hypothalamus may be a combination of alterations in downstream processes beyond gene transcription. This research brings novel insights into the sexually distinct consequences of chronic stress, an essential aspect to understand, particularly concerning its role in the development of depression.

Activation of Hypoxia Inducible Factor-1 Alpha-Mediated DNA Methylation Enzymes (DNMT3a and TET2) Under Hypoxic Conditions Regulates S100A6 Transcription to Promote Lung Cancer Cell Growth and Metastasis

Aims: This research was aimed at investigating the effects of hypoxia inducible factor-1 alpha (HIF-1α)-mediated DNA methylation enzymes (ten-eleven translocase-2 [TET2] and DNA methyltransferase-3a [DNMT3a]) under hypoxic conditions on S100A6 transcription, thereby promoting the growth and metastasis of lung cancer cells. Methods: The expression of HIF-1α or S100A6 in lung cancer cells was interfered with under normoxic and hypoxic conditions, and the cell proliferative, migratory, and invasive properties were assessed. The mechanism of HIF-1α-regulated TET2 and DNMT3 effects on S100A6 transcription under hypoxic conditions was further investigated. Results: Functionally, S100A6 over-expression promoted lung cancer cell proliferation and metastasis. S100A6 over-expression reversed the inhibitory effects of HIF-1α interference on the proliferation and metastasis of lung cancer cells. S100A6 was induced to express in an HIF-1α-dependent manner under hypoxic conditions, and silencing S100A6 or HIF-1α suppressed lung cancer cell proliferation and metastasis under hypoxic conditions. Further, The Cancer Genome Atlas-lung adenocarcinoma database analysis revealed that S100A6 mRNA levels had a negative correlation with methylation levels. Mechanistically, CpG hypomethylation status in the S100A6 promoter hypoxia response element had an association with HIF-1α induction. TET2 was enriched in S100A6 promoter region of lung cancer cells under hypoxic conditions, whereas DNMT3a enrichment was reduced in S100A6 promoter region. HIF-1α-mediated S100A6 activation was linked to DNMT3a-associated epigenetic inactivation and TET2 activation. Innovation: The activation of HIF-1α-mediated DNA methylation enzymes under hypoxic conditions regulated S100A6 transcription, thereby promoting lung cancer cell growth and metastasis. Conclusion: In lung cancer progression, hypoxia-induced factor HIF-1α combined with DNA methylation modifications co-regulates S100A6 transcriptional activation and promotes lung cancer cell growth and metastasis.

DNMT3a-mediated upregulation of the stress inducible protein sestrin-2 contributes to malignant transformation of human bronchial epithelial cells following nickel exposure

BACKGROUND

Nickel is a confirmed human lung carcinogen. Nonetheless, the molecular mechanisms driving its carcinogenic impact on lung tissue remain poorly defined. In this study, we assessed SESN2 expression and the signaling pathways responsible for cellular transformation in human bronchial epithelial cells (HBECs) as a result of nickel exposure.

METHODS

We employed the Western blotting to determine the induction of SESN2 by nickel. To clarify the signaling pathways leading to cellular transformation following nickel exposure, we applied techniques such as gene knockdown, methylation-specific PCR, and chromatin immunoprecipitation.

RESULT

Exposure to nickel results in the upregulation of SESN2 and the initiation of autophagy in human bronchial epithelial cells (HBECs). This leads to degradation of HUR protein and consequently downregulation of USP28 mRNA, PP2AC protein, β-catenin protein, and diminished VHL transcription, culminating in the accumulation of hypoxia-inducible factor-1α (HIF-1α) and the malignant transformation of these cells. Mechanistic studies revealed that the increased expression of SESN2 is attributed to the demethylation of the SESN2 promoter induced by nickel, a process facilitated by decreased DNA methyl-transferase 3 A (DNMT3a) expression, while The downregulation of VHL transcription is linked to the suppression of the PP2A-C/GSK3β/β-Catenin/C-Myc pathway. Additionally, we discovered that SESN2-mediated autophagy triggers the degradation of HUR protein, which subsequently reduces the stability of USP28 mRNA and inhibits the PP2A-C/GSK3β/β-Catenin pathway and c-Myc transcription in HBECs post nickel exposure.

CONCLUSION

Our results reveal that nickel exposure leads to the downregulation of DNMT3a, resulting in the hypomethylation of the SESN2 promoter and its protein induction. This triggers autophagy-dependent suppression of the HUR/USP28/PP2A/β-Catenin/c-Myc pathway, subsequently leading to reduced VHL transcription, accumulation of HIF-1α protein, and the malignant transformation of human bronchial epithelial cells (HBECs). Our research offers novel insights into the molecular mechanisms that underlie the lung carcinogenic effects of nickel exposure. Specifically, nickel induces aberrant DNA methylation in the SESN2 promoter region through the decrease of DNMT3a levels, which ultimately leads to HIF-1α protein accumulation and the malignant transformation of HBECs. Specifically, nickel initiates DNA-methylation of the SESN2 promoter region by decreasing DNMT3a, ultimately resulting in HIF-1α protein accumulation and malignant transformation of HBECs. This study highlights DNMT3a as a potential prognostic biomarker or therapeutic target to improve clinical outcomes in lung cancer patients.

DNA methyltransferase 3a-induced hypermethylation of the fructose-1,6-bisphosphatase-2 promoter contributes to gastric carcinogenesis

BACKGROUND

Aberrant DNA methylation has been implicated in the development of gastric cancer (GC). In our previous study, we demonstrated that fructose-1,6-bisphosphatase-2 (FBP2), an enzyme that suppresses cell glycolysis and growth, is downregulated in GC due to promoter methylation. However, the precise mechanism underlying this process remains unknown. Thus, this study aimed to elucidate the mechanisms involved in FBP2 promoter hypermethylation.

METHODS AND RESULTS

The methylation levels in GC and normal adjacent tissues were quantified using methylation-specific polymerase chain reaction. FBP2 promoter was frequently hypermethylated in primary GC tissues compared to adjacent normal tissues. To explore the functional consequences of this hypermethylation, we employed small interfering RNA-mediated knockdown of DNA methyltransferase 3a (DNMT3a) in GC cells. FBP2 expression increased following DNMT3a knockdown, suggesting that reduced methylation of the FBP2 promoter contributed to this upregulation. To further investigate this interaction, chromatin immunoprecipitation assays were conducted. The results confirmed an interaction between DNMT3a and the FBP2 promoter region, providing evidence that DNMT3a-mediated hypermethylation of the FBP2 promoter promotes GC progression.

CONCLUSIONS

This study provides evidence that DNMT3a is involved in the hypermethylation of the FBP2 promoter and regulation of GC cell metabolism. Hypermethylation of the FBP2 promoter may be a promising prognostic biomarker in GC.

DNMT3a-mediated methylation of PPARγ promote intervertebral disc degeneration by regulating the NF-κB pathway

Intervertebral disc degeneration (IVDD) is a common chronic musculoskeletal disease that causes chronic low back pain and imposes an immense financial strain on patients. The pathological mechanisms underlying IVDD have not been fully elucidated. The development of IVDD is closely associated with abnormal epigenetic changes, suggesting that IVDD progression may be controlled by epigenetic mechanisms. Consequently, this study aimed to investigate the role of epigenetic regulation, including DNA methyltransferase 3a (DNMT3a)-mediated methylation and peroxisome proliferator-activated receptor γ (PPARγ) inhibition, in IVDD development. The expression of DNMT3a and PPARγ in early and late IVDD of nucleus pulposus (NP) tissues was detected using immunohistochemistry and western blotting analyses. Cellularly, DNMT3a inhibition significantly inhibited IL-1β-induced apoptosis and extracellular matrix (ECM) degradation in rat NP cells. Pretreatment with T0070907, a specific inhibitor of PPARγ, significantly reversed the anti-apoptotic and ECM degradation effects of DNMT3a inhibition. Mechanistically, DNMT3a modified PPARγ promoter hypermethylation to activate the nuclear factor-κB (NF-κB) pathway. DNMT3a inhibition alleviated IVDD progression. Conclusively, the results of this study show that DNMT3a activates the NF-κB pathway by modifying PPARγ promoter hypermethylation to promote apoptosis and ECM degradation. Therefore, we believe that the ability of DNMT3a to mediate the PPARγ/NF-κB axis may provide new ideas for the potential pathogenesis of IVDD and may become an attractive target for the treatment of IVDD.

p53 promotes the expansion of regulatory T cells via DNMT3a- and TET2- mediated Foxp3 expression in sepsis

Background

Immunosuppression is an important characteristic of sepsis and is closely related to poor outcomes. Regulatory T cells (Tregs) contribute to immune suppression by inhibiting effector T cell (Teff) proliferation and differentiation. We aimed to investigate the role of p53 in Treg expansion after sepsis.

Methods

We constructed a sepsis model in wild-type (WT) and p53f/f/CD4-Cre+ mice by cecal ligation and puncture (CLP) and evaluated the proportions of CD4+CD25+ Foxp3+ Tregs by flow cytometry. The expression levels of forkhead/winged helix transcription factor p3 (Foxp3), DNA methyltransferase enzyme (DMNT)3a and ten-eleven translocation (TET)2 were examined using quantitative real-time PCR and Western blot analysis. Treg-specific demethylation region (TSDR) methylation sites in cells were analyzed by bisulfite-sequencing PCR. Furthermore, the direct binding of p53 to the Dnmt3a and TET2 promoters was illustrated using a luciferase assay. The suppressive ability of Tregs was indicated by enzyme-linked immunosorbent assay analysis of cytokine levels and the proliferation of cocultured Teffs. Finally, mortality rates after CLP were compared among WT and p53f/f/CD4-Cre+ mice.

Results

The proportion of CD4+CD25+ Foxp3+ Tregs was significantly reduced in p53f/f/CD4-Cre+ mice compared to WT mice after CLP. The enhanced expression of Foxp3 in WT mice was downregulated in the p53f/f/CD4-Cre+ group. We found decreased DMNT3a and increased TET2 levels after CLP. However, the dysregulation of DNMT3a and TET2 was significantly reversed in p53f/f/CD4-Cre+ mice. TSDR underwent increased demethylation in p53f/f/CD4-Cre+ mice. Luciferase activity indicated direct binding of p53 to the promoter regions of DNMT3a and TET2 to regulate their transcription. Consequently, Tregs from p53f/f/CD4-Cre+ CLP mice exhibited limited suppressive ability, as indicated by the reduced production of transforming growth factor-β and interleukin 10 (IL-10). In the coculture system, Teffs showed preserved production of IL-2, differentiation into Th1 cells and proliferation in the presence of Tregs isolated from p53f/f/CD4-Cre+ CLP mice. Finally, the mortality rate of the p53f/f/CD4-Cre+ group after CLP was significantly reduced in comparison to that of the WT group.

Conclusion

p53 appears to be critical for Foxp3 expression and consequent Treg expansion by regulating the induction of DNMT3a and TET2, thereby resulting in Foxp3-TSDR demethylation in the context of sepsis.

RNautophagic regulation of DNMT3a-dependent DNA methylation by Linc00942 enhances chemoresistance in gastric cancer

BACKGROUND

Energy balance has long been known to extend lifespans and inhibit carcinogenesis in multiple species by slowing age-related epigenetic changes while the underlying mechanisms remain largely unknown. Herein, we found that starvation activated autophagy to remodel the DNA methylation profile by inhibiting DNMT3a expression.

METHODS

Illumina Infinium MethylationEPIC BeadChip and dot blot assay were performed to quantify the global DNA methylation level. Protein-RNA interactions were validated through RNA immunoprecipitation and RNA pull-down assay. In vitro and in vivo experiments were carried out to testify the effect of DNMT3a on chemoresistance.

RESULTS

Autophagy is impaired in chemoresistance which was associated with differential DNA methylation and could be reversed by DNMT3a inhibition. Autophagy activation decreases the expression of DNMT3a mRNA, accompanied with the downregulation of chemoresistance-related Linc00942. Knockdown of Linc00942 reduces DNMT3a expression and genome-wide DNA methylation while Linc00942 overexpression increased DNMT3a expression and correlated hypermethylation in cancer cells and primary tumour tissues. Mechanistically, Linc00942 recruits RNA methyltransferase METTL3 to stimulate N6-methyladenosine (m6A) deposit on DNMT3a transcripts, triggering IGF2BP3/HuR to recognize modified mRNA for reinforced stability. SQSTM1/p62 recruits Linc00942 for autophagic degradation which can be abrogated after autophagy inhibition by p62 knockdown or chloroquine treatment.

CONCLUSIONS

Inhibition of autophagy increases Linc00942 expression to promote chemoresistance and autophagy activation or hypomethylating agent decitabine restores chemosensitivity by reducing global DNA methylation. Overall, this study identifies a novel methylation cascade linking impaired RNautophagy to global hypermethylation in chemoresistance, and provides a rationale for repurposing decitabine to overcome chemoresistance in cancer treatment.

DNMT3a-mediated methylation of TCF21/hnRNPA1 aggravates hepatic fibrosis by regulating the NF-κB signaling pathway

Hepatic fibrosis is caused by liver damage as a consequence of wound healing response. Recent studies have shown that hepatic fibrosis could be effectively reversed, partly through regression of activated hepatic stellate cells (HSCs). Transcription factor 21 (TCF21), a member of the basic helix-loop-helix (bHLH) transcription factor, is involved in epithelial-mesenchymal transformation in various diseases. However, the mechanism by which TCF21 regulates epithelial-mesenchymal transformation in hepatic fibrosis has not been elucidated. In this research, we found that hnRNPA1, the downstream binding protein of TCF21, accelerates hepatic fibrosis reversal by inhibiting the NF-κB signaling pathway. Furthermore, the combination of DNMT3a with TCF21 promoter results in TCF21 hypermethylation. Our results suggest that DNMT3a regulation of TCF21 is a significant event in reversing hepatic fibrosis. In conclusion, this research identifies a novel signaling axis, DNMT3a-TCF21-hnRNPA1, that regulates HSCs activation and hepatic fibrosis reversal, providing a novel treatment strategy for hepatic fibrosis. The clinical trial was registered in the Research Registry (researchregistry9079).

Epigenetic modifications as therapeutic targets in atherosclerosis: a focus on DNA methylation and non-coding RNAs

Significant progress in the diagnosis and treatment of cardiovascular disease (CVD) has been made in the past decade, yet it remains a leading cause of morbidity and mortality globally, claiming an estimated 17.9 million deaths per year. Although encompassing any condition that affects the circulatory system, including thrombotic blockage, stenosis, aneurysms, blood clots and arteriosclerosis (general hardening of the arteries), the most prevalent underlying hallmark of CVD is atherosclerosis; the plaque-associated arterial thickening. Further, distinct CVD conditions have overlapping dysregulated molecular and cellular characteristics which underlie their development and progression, suggesting some common aetiology. The identification of heritable genetic mutations associated with the development of atherosclerotic vascular disease (AVD), in particular resulting from Genome Wide Association Studies (GWAS) studies has significantly improved the ability to identify individuals at risk. However, it is increasingly recognised that environmentally-acquired, epigenetic changes are key factors associated with atherosclerosis development. Increasing evidence suggests that these epigenetic changes, most notably DNA methylation and the misexpression of non-coding, microRNAs (miRNAs) are potentially both predictive and causal in AVD development. This, together with their reversible nature, makes them both useful biomarkers for disease and attractive therapeutic targets potentially to reverse AVD progression. We consider here the association of aberrant DNA methylation and dysregulated miRNA expression with the aetiology and progression of atherosclerosis, and the potential development of novel cell-based strategies to target these epigenetic changes therapeutically.

Decreased SUV39H1 at the promoter region leads to increased CREMα and accelerates autoimmune response in CD4+ T cells from patients with systemic lupus erythematosus

BACKGROUND

Overproduction of cAMP-responsive element modulator α (CREMα) in total T cells from patients with systemic lupus erythematosus (SLE) can inhibit IL-2 and increase IL-17A. These ultimately promote progression of SLE. This study aims to investigate the expression of CREMα in SLE CD4⁺ T cells and find out the mechanisms for the regulation of CREMα in SLE CD4⁺ T cells.

RESULTS

CREMα mRNA was overexpressed in CD4⁺ T cells from SLE patients. The levels of histone H3 lysine 9 trimethylation (H3K9me3) and suppressor of variation 3-9 homolog 1 (SUV39H1) at the CREMα promoter of SLE CD4⁺ T cells were markedly decreased. Down-regulating SUV39H1 in normal CD4⁺ T cells elevated the levels of CREMα, IL-17A, and histone H3 lysine 4 trimethylation (H3K4me3) in the CREMα promoter region, and lowered IL-2, H3K9me3, DNA methylation, and DNA methyltransferase 3a (DNMT3a) enrichments within the CREMα promoter, while no sharp change in SET domain containing 1 (Set1) at the CREMα promoter. Up-regulating SUV39H1 in SLE CD4⁺ T cells had the opposite effects. The DNA methylation and DNMT3a levels were obviously reduced, and H3K4me3 enrichment was greatly increased at the CREMα promoter of CD4⁺ T cells from SLE patients. The Set1 binding in the CREMα promoter region upgraded significantly, and knocking down Set1 in SLE CD4⁺ T cells alleviated the H3K4me3 enrichment within this region, suppressed CREMα and IL-17A productions, and promoted the levels of IL-2, CREMα promoter DNA methylation, and DNMT3a. But there were no obviously alterations in H3K9me3 and SUV39H1 amounts in the region after transfection.

CONCLUSIONS

Decreased SUV39H1 in the CREMα promoter region of CD4⁺ T cells from SLE patients contributes to under-expression of H3K9me3 at this region. In the meantime, the Set1 binding at the CREMα promoter of SLE CD4⁺ T cells is up-regulated. As a result, DNMT3a and DNA methylation levels alleviate, and H3K4me3 binding increases. All these lead to overproduction of CREMα. Thus, the secretion of IL-2 down-regulates and the concentration of IL-17A up-regulates, ultimately promoting SLE.

DNMT3a negatively regulates PTEN to activate the PI3K/AKT pathway to aggravate renal fibrosis

BACKGROUND

Renal fibrosis has become one of the major diseases threatening global public health and harming human life and health. PTEN methylation plays an important role in fibrotic diseases of many organs. However, the relationship between PTEN methylation and renal fibrosis is still elusive.

METHODS

In the present study, we established a unilateral ureteral obstruction (UUO) mouse model in vivo and a transforming growth factor β1 (TGF-β1)-stimulated renal tubular epithelial cell (HK-2) model in vitro. The degree of renal interstitial fibrosis was detected by haematoxylin-eosin (HE) staining and Masson's trichrome staining. Western blot (WB), qRT-PCR, immunohistochemistry (IHC) and methylation-specific PCR (MSP) analyses were used to determine the mechanism by which PTEN methylation regulates renal fibrosis. The α-SMA fibrosis marker was detected by immunofluorescence (IF). Additionally, the relationship of PTEN and DNMT3a in UUO was determined by ChIP-qRT-PCR.

RESULTS

Our results showed that the promoter region of PTEN was methylated in UUO. Compared to the sham group, the expression of PTEN was significantly reduced in the UUO group. However, the demethylation reagent significantly inhibited epithelial-mesenchymal transition (EMT), which showed increased expression of E-cadherin and decreased expression of α-SMA and fibronectin. Moreover, treatment of HK-2 cells with 5-aza-dc reversed the activation of the TGF-β1-induced PI3K/AKT signalling pathway, which inhibited renal fibrosis. WB analysis demonstrated that TGF-β1 inhibited the PTEN protein expression level and DNMT3a knockdown reversed the inhibitory effect of TGF-β1 on PTEN expression. Furthermore, ChIP-qRT-PCR showed that DNMT3a interacted with PTEN. Finally, we found that DNMT3a negatively regulated PTEN to activate the PI3K/AKT signalling pathway and aggravate renal fibrosis in vitro and in vivo.

CONCLUSION

In summary, these results indicated that renal fibrosis is related to the downregulation of PTEN. Additionally, DNMT3a negatively regulates PTEN to activate the PI3K/AKT signalling pathway and induce EMT in renal tubular epithelial cells, thereby aggravating renal fibrosis.

Low-intensity pulsed ultrasound prevents prolonged hypoxia-induced cardiac fibrosis through HIF-1α/DNMT3a pathway via a TRAAK-dependent manner

Hypoxia-induced cardiac fibrosis is an important pathological process in cardiovascular disorders. This study aimed to determine whether low-intensity pulsed ultrasound (LIPUS), a novel and safe apparatus, could alleviate hypoxia-induced cardiac fibrosis, and to elucidate the underlying mechanisms. Hypoxia (1% O2 ) and transverse aortic constriction (TAC) were performed on neonatal rat cardiac fibroblasts and mice to induce cardiac fibrosis, respectively. LIPUS irradiation was applied for 20 minutes every 6 hours for a total of 2 times in vitro, and every 2 days from 1 week before surgery to 4 weeks after surgery in vivo. We found that LIPUS dose-dependently attenuated hypoxia-induced cardiac fibroblast phenotypic conversion in vitro, and ameliorated TAC-induced cardiac fibrosis in vivo. Hypoxia significantly upregulated the nuclear protein expression of hypoxia-inducible factor-1α (HIF-1α) and DNA methyltransferase 3a (DNMT3a). LIPUS pre-treatment reversed the elevated expression of HIF-1α, and DNMT3a. Further experiments revealed that HIF-1α stabilizer dimethyloxalylglycine (DMOG) hindered the anti-fibrotic effect of LIPUS, and hampered LIPUS-mediated downregulation of DNMT3a. DNMT3a small interfering RNA (siRNA) prevented hypoxia-induced cardiac fibrosis. Results also showed that the mechanosensitive protein-TWIK-related arachidonic acid-activated K+ channel (TRAAK) messenger RNA (mRNA) expression was downregulated in hypoxia-induced cardiac fibroblasts, and TAC-induced hearts. TRAAK siRNA impeded LIPUS-mediated anti-fibrotic effect and downregulation of HIF-1α and DNMT3a. Above results indicated that LIPUS could prevent prolonged hypoxia-induced cardiac fibrosis through TRAAK-mediated HIF-1α/DNMT3a signalling pathway.

Adolescent cannabinoid exposure modulates the vulnerability to cocaine-induced conditioned place preference and DNMT3a expression in the prefrontal cortex in Swiss mice

RATIONALE

Cannabis sativa is the most widely used drug by adolescents globally. The recreational use of synthetic cannabinoids by teenagers has also grown in recent years. Despite the wrong perception that exposure to these drugs does not cause harm, repeated exposure to cannabinoids at early stages of life compromises important maturation processes and brain development. Chronic early cannabinoid use has been related to a higher risk of psychiatric outcomes, including cocaine addiction. Evidence suggests that exposure to natural and synthetic cannabinoids during adolescence modifies molecular and behavioral effects of cocaine in adulthood. Responses to cocaine are regulated by epigenetic mechanisms, such as DNA methylation, in the brain's reward regions. However, the involvement of these processes in modulation of the vulnerability to the effects of cocaine induced by prior exposure to cannabinoids remains poorly understood.

OBJECTIVES

Investigate whether exposure to the synthetic cannabinoid WIN55,212-2 during adolescence modulates anxiety- and depression-like behavior, memory, and cocaine reward in adult mice. We also evaluated whether exposure to cannabinoids during adolescence modulates the expression of enzymes that are involved in DNA methylation.

RESULTS

Exposure to WIN55,212-2 during adolescence did not alter anxiety- or depressive-like behavior. However, prior exposure to cannabinoids inhibited cocaine-induced conditioned place preference without modulating cocaine-induced hyperlocomotion, accompanied by an increase in expression of the enzyme DNA methyltransferase 3a (DNMT3a) in the prefrontal cortex.

CONCLUSIONS

Our findings suggest that exposure to WIN55,212-2 during adolescence leads to changes in DNMT3a expression, and this pathway appears to be relevant to modulating the rewarding effects of cocaine.

Upregulation of ubiquitin conjugating enzyme E2B (Ube2b) ameliorates neuropathic pain by regulating Kcna2 (potassium voltage-gated channel subfamily A member 2) in primary afferent neurons

Neuropathic pain is a kind of pain caused by damage to somatosensory nervous system. Currently, neuropathic pain is still a medical problem for clinicians. Ubiquitin conjugating enzyme E2B (Ube2b) is validated to be implicated with nerve function, but whether Ube2b can play a role in neuropathic pain is still elusive. In this work, we constructed chronic constriction injury (CCI) rat model by ligating the left sciatic nerve, Ube2b protein expression was confirmed to be decreased in spinal cord tissues of CCI rats via Western blot analysis and immunofluorescence (IF) staining. Moreover, Ube2b elevation alleviated the thermal hyperalgesia and mechanical hyperalgesia in CCI rats according to paw withdrawal thermal latency (PWTL) and paw withdrawal mechanic threshold (PWMT). In addition, Hematoxylin-eosin staining revealed that Ube2b elevation suppressed chronic sciatic nerve injury. All these data suggested that Ube2b could ameliorate neuropathic pain in CCI rats. Mechanically, Ube2b upregulation elevated the protein level of Kcna2 (potassium voltage-gated channel subfamily A member 2) and decreased the protein level of DNMT3a (DNA methyltransferase 3 alpha). Ube2b elevation could increase Kcna2 expression via suppressing DNMT3a. Rescue assays unveiled that Ube2b overexpression modulated-mechanical hyperalgesia and thermal hyperalgesia were reversed by Kcna2 depletion, indicating that Ube2b alleviated neuropathic pain via mediating Kcna2 via the regulation of DNMT3a. In summary, we found that Ube2b elevation ameliorated neuropathic pain through regulating Kcna2, which might offer a novel biomarker for the therapies of neuropathic pain.

Downregulation of DNMT3a expression by RNAi and its effect on NF-κBs expression of thymic epithelial cells

OBJECTIVE

To understand the characteristics of DNA methyltransferase 3a (DNMT3a) in thymoma associated Myasthenia Gravis reveal its transcriptional regulator network as while as analyze the effect of DNMT3a on Rel/ nuclear factor-kappaB family (RelA/RelB) and its downstream autoimmune regulatory factor (Aire).

METHODS

Tissues of 30 patients with thymoma, with or without myasthenia gravis (MG), were collected and the DNMT3a protein expression were evaluated through immunohistochemistry. We performed mRNA expression profiling microarray detection and analysis, and integrated the analysis by constructing protein-protein interaction networks and the integration with other database. We identified molecular difference between low and high DNMT3a in the thymoma by heatmap. We also performed PCR validation in thymoma tissues. The DNMT3a-shRNA plasmid was transfected into TEC cells, and these cells were treated with 5-aza-2-deoxycytidine, a blocker of DNMT3a. After the down-regulation of DNMT3a in TEC cells, the transcript and protein levels of RelA, RelB, Aire, and CHRNA3 were evaluated by western blotting. In addition, changes in gene expression profiles were screened through microarray technology. We performed differential gene analysis in the thymoma cohort by heatmap with R (v.4.3.0) software.

RESULTS

In 30 matched tissue specimens, the expression of DNMT3a protein in thymoma with MG was lower than that in thymoma. Through mRNA expression profiling analysis, we constructed a co-expression network of DNMT3a and found direct interaction between IKZF1 and DNMT3a, and this co-expression relationship was overlappted with Cistrome DB database. We found up-regulation of 149 mRNAs and repression of 177 mRNAs in thymoma with MG compared with thymoma. Gene ontology and pathway analysis show the involvement of a multitude of genes in the mis-regulation of MG-related pathways. RNA interference significantly reduced the level of mRNA of DNMT3a, which proved that plasmid DNMT3a was effective. In comparison to the control group, the levels of DNMT3a, Aire, and CHRNA3 mRNA and protein in TEC cells transfected with DNMT3a-shRNA interference plasmid were significantly decreased, while the expression level of RelA and RelA/RelB was significantly increased.

CONCLUSIONS

Our study reveals the DNMT3a-NF-κB pathway has a major effect on MG, and can be used as a marker for diagnosis as well as a target for MG treatment.

Co-Targeting Plk1 and DNMT3a in Advanced Prostate Cancer

Because there is no effective treatment for late-stage prostate cancer (PCa) at this moment, identifying novel targets for therapy of advanced PCa is urgently needed. A new network-based systems biology approach, XDeath, is developed to detect crosstalk of signaling pathways associated with PCa progression. This unique integrated network merges gene causal regulation networks and protein-protein interactions to identify novel co-targets for PCa treatment. The results show that polo-like kinase 1 (Plk1) and DNA methyltransferase 3A (DNMT3a)-related signaling pathways are robustly enhanced during PCa progression and together they regulate autophagy as a common death mode. Mechanistically, it is shown that Plk1 phosphorylation of DNMT3a leads to its degradation in mitosis and that DNMT3a represses Plk1 transcription to inhibit autophagy in interphase, suggesting a negative feedback loop between these two proteins. Finally, a combination of the DNMT inhibitor 5-Aza-2'-deoxycytidine (5-Aza) with inhibition of Plk1 suppresses PCa synergistically.

Cigarette smoke extract promotes DNA methyltransferase 3a expression in dendritic cells, inducing Th-17/Treg imbalance via the c-Jun/allograft inflammatory factor 1 axis

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disorder. Although numerous studies on COPD have been conducted, therapeutic strategies for COPD are limited, and its pathological mechanism is still unclear. The present study aimed to explore the role of DNA methyltransferase 3a (DNMT3a) in dendritic cells (DCs) and the possible role of the Th-17/Treg cell balance in COPD. Immature DCs (iDCs) were induced and cocultured with CD4⁺ T cells. An in vitro COPD model was established by treatment with cigarette smoke extract (CSE). DNMT3a or allograft inflammatory factor 1 (AIF1) and c-Jun N-terminal kinase (JNK) were inhibited and overexpressed, respectively, by transfection with sh-DNMT3a or sh-AIF1 and JNK overexpression plasmids. The 3- (4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to measure cell viability. The Th17/Treg cell ratio was determined by flow cytometry. The expression levels of DNMT3a, c-Jun and AIF1 were measured using RT-qPCR or western blotting. Chromatin immunoprecipitation (CHIP) was used to confirm the interaction between c-Jun and the AIF1 promoter region. CSE stimulation promoted the expression of DNMT3a, and AIF1, and the ratio of p-c-Jun/c-Jun in iDCs. Besides, the iDC-mediated differentiation of Th17 cells was in a dose-dependent manner. However, knockdown of DNMT3a or AIF1 reversed the above effects caused by CSE. Inhibition of c-Jun signaling by treatment with the JNK inhibitor SP600125 also suppressed the iDC-mediated differentiation of Th17 cells, which was promoted by CSE. CHIP analysis showed that c-Jun could bind to the promoter region of AIF1. DNMT3a could regulate the iDC-mediated Th17/Treg balance by regulating the c-Jun/AIF1 axis.

Upregulation of miR-137 Expression Suppresses Tumor Growth and Progression via Interacting with DNMT3a Through Inhibiting the PTEN/Akt Signaling in HCC

Background

Downregulation of miR-137 regulates tumor growth in hepatocellular carcinoma (HCC). Yet, the underlying molecular mechanisms stay unclear.

Materials and Methods

miR-137 and DNA methyltransferase 3a (DNMT3a) expression levels were detected by Western blot, immunohistochemistry and qRT-PCR assays. Luciferase reporter and Western blot assays were also carried out to explore the correlation of miR-137 and DNMT3a. Flow cytometry assay, MTT analysis, transwell and wound healing assay were used to evaluate cell apoptosis, proliferation, as well as invasive and migratory abilities. Western blot was used to examine the caspase-3, cleaved caspase-3, PCNA, MMP-2, and MMP-7 protein levels, as well as PTEN/Akt signaling alternations. Methylation-specific PCR was applied to detect the PTEN promoter methylation status. Xenograft tumor assay, Western blot and immunohistochemistry analyses were taken to confirm the miR-137 regulation in vivo.

Results

Downregulation of miR-137, upregulation of DNMT3a, as well as an inverse correlation between them were observed in HCC clinical samples and cells. Moreover, miR-137 targeted directly and inhibited DNMT3a in HCC cells, which further retarded cell proliferative, migratory and invasive capabilities, while promoted apoptotic ones. Additionally, miR-137 overexpression inactivated the PTEN/Akt pathway in HCC cell by decreasing DNMT3a expression. Furthermore, miR-137 overexpression inhibited tumor growth in vivo in HCC via interacting with DNMT3a through inhibiting the PTEN/Akt cascades.

Conclusion

Our findings suggested that miR-137 inhibited HCC tumor growth and progression via interacting with DNMT3a and suppressing the PTEN/Akt signaling in vitro and in vivo.

Gene body methylation facilitates the transcription of CTSG via antisense lncRNA AL136018.1 in dermatomyositic myoideum

Dermatomyositis (DM) is characterized as a chronic autoimmune disorder with multiple organ involvement. Our previous study has revealed that Cathepsin G (CTSG) highly expressed in dermatomyositic in vivo is regulated by DNMT3a through DNA methylation of 5'-C-phosphate-G-3' loci at exons and introns. However, the mechanism of gene body methylation on regulating CTSG transcription remains unknown. In this study, we studied quadriceps femoris tissues of six DM patients, and observed that antisense long noncoding RNA AL136018.1 contiguous to CTSG was highly expressed in skeletal muscle tissues of DM and positively correlated with the transcription level and DNA methylation level in gene body of CTSG in vivo. Moreover, we observed that the longer transcript of AL136018.1 (AL136018.1-201) could bind to third and fourth exons and third intron of CTSG via the 3'-end. Finally, AL136018.1-201 could recruit DNMT3a towards gene body via 5'-terminal for adding DNA methylation and facilitating transcription of CTSG. Taken together, our data uncovered a novel epigenetic mechanism behind the gene body methylation for transcriptional regulation of CTSG in DM.

CircSOD2 induced epigenetic alteration drives hepatocellular carcinoma progression through activating JAK2/STAT3 signaling pathway

Background

Emerging evidence suggests that circular RNAs play critical roles in disease development especially in cancers. Previous genome-wide RNA-seq studies found that a circular RNA derived from SOD2 gene was highly upregulated in hepatocellular carcinoma (HCC), however, the role of circSOD2 in HCC remains largely unknown.

Methods

The expression profiling of circSOD2 and microRNA in HCC patients were assessed by Real-Time Quantitative Reverse Transcription PCR (qRT-PCR). SiRNA or CRISPR-CAS9 were used to silence gene expression. The biological function of circSOD2 in HCC was investigated using in vitro and in vivo studies including, trans-well cell migration, cell apoptosis, cell cycle, CCK8, siRNA interference, western blots, and xenograft mouse model. The underlying molecular mechanism was determined by Chromatin Immunoprecipitation quantitative real time PCR (ChIP-qPCR), bioinformatic analysis, biotin-pull down, RNA immunoprecipitation, 5-mc DNA pulldown and luciferase assays.

Results

In accordance with previous sequencing results, here, we demonstrated that circSOD2 was highly expressed in HCC tumor tissues compared with normal liver tissues. Mechanically, we showed that histone writer EP300 and WDR5 bind to circSOD2 promoter and trigger its promoter H3K27ac and H3K4me3 modification, respectively, which further activates circSOD2 expression. SiRNA mediated circSOD2 suppression impaired liver cancer cell growth, cell migration, prohibited cell cycle progression and in vivo tumor growth. By acting as a sponge, circSOD2 inhibits miR-502-5p expression and rescues miR-502-5p target gene DNMT3a expression. As a DNA methyltransferase, upregulated DNMA3a suppresses SOCS3 expression by increasing SOCS3 promoter DNA methylation. This event further accelerates SOCS3 downstream JAK2/STAT3 signaling pathway activation. In addition, we also found that activated STAT3 regulates circSOD2 expression in a feedback way.

Conclusion

The novel signaling axis circSOD2/miR-502-5p/DNMT3a/JAK2/STAT3/circSOD2 provides a better understanding of HCC tumorigenesis. The molecular mechanism underlying this signaling axis offers new prevention and treatment of HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01769-7.

Investigating the Relationship Between Neuronal Cell Death and Early DNA Methylation After Ischemic Injury

Cerebral ischemia induces neuronal cell death and causes various kinds of brain dysfunction. Therefore, prevention of neuronal cell death is most essential for protection of the brain. On the other hand, it has been reported that epigenetics including DNA methylation plays a pivotal role in pathogenesis of some diseases such as cancer. Accumulating evidences indicate that aberrant DNA methylation is related to cell death. However, DNA methylation after cerebral ischemia has not been fully understood yet. The aim of this present study was to investigate the relationships between DNA methylation and neuronal cell death after cerebral ischemia. We examined DNA methylation under the ischemic condition by using transient middle cerebral artery occlusion and reperfusion (MCAO/R) model rats and N-methyl-D-aspartate (NMDA)–treated cortical neurons in primary culture. In this study, we demonstrated that DNA methylation increased in these neurons 24 h after MCAO/R and that DNA methylation, possibly through activation of DNA methyltransferases (DNMT) 3a, increased in such neurons immediately after NMDA treatment. Furthermore, NMDA-treated neurons were protected by treatment with a DNMT inhibitor that were accompanied by inhibition of DNA methylation. Our results showed that DNA methylation would be an initiation factor of neuronal cell death and that inhibition of such methylation could become an effective therapeutic strategy for stroke.

The expression of DNMTs is dramatically decreased in peripheral blood mononuclear cells of male patients with juvenile idiopathic arthritis

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is an autoimmune rheumatic disease, which affects primarily the joints in children under 16 years old. The etiology of JIA is yet unknown but research has shown that JIA is a multifactorial disease implicating several genes and environmental factors. Environmental factors affect immune cells via epigenetic mechanisms. One of the most important epigenetic mechanisms is DNA methylation catalyzed by DNA methyltransferases (DNMTs) and usually associated with gene silencing. In this study, we analyzed the expression of three DNA methyltransferases namely DNMT1, DNMT3a and DNMT3b in peripheral blood mononuclear cells (PBMCs) of patients with JIA and compared it with the expression of these genes in healthy young individuals.

MATERIALS AND METHODS

Peripheral blood mononuclear cells of 28 JIA patients and 28 healthy controls were isolated. Total RNA was extracted, cDNA was synthesized and the transcript levels of DNMTs were analyzed by quantitative PCR.

RESULTS

Analysis of DNMT1, DNMT3a and DNMT3b relative gene expression in PBMCs of JIA patients and control individuals shows that the expression of DNMT1 and DNMT3a is reduced significantly by 7 folds and 5.5 folds, respectively, in JIA patients compared to healthy controls. Furthermore, the expression of all three DNMTs were significantly and drastically reduced in young affected males compared to healthy males.

CONCLUSION

This study shows that the expression of DNMTs is reduced in JIA patients and this reduction is severe in male JIA patients.

DNMT3a in the hippocampal CA1 is crucial in the acquisition of morphine self-administration in rats

Drug-reinforced excessive operant responding is one fundamental feature of long-lasting addiction-like behaviors and relapse in animals. However, the transcriptional regulatory mechanisms responsible for the persistent drug-specific (not natural rewards) operant behavior are not entirely clear. In this study, we demonstrate a key role for one of the de novo DNA methyltransferase, DNMT3a, in the acquisition of morphine self-administration (SA) in rats. The expression of DNMT3a in the hippocampal CA1 region but not in the nucleus accumbens shell was significantly up-regulated after 1- and 7-day morphine SA (0.3 mg/kg/infusion) but not after the yoked morphine injection. On the other hand, saccharin SA did not affect the expression of DNMT3a or DNMT3b. DNMT inhibitor 5-aza-2-deoxycytidine (5-aza) microinjected into the hippocampal CA1 significantly attenuated the acquisition of morphine SA. Knockdown of DNMT3a also impaired the ability to acquire the morphine SA. Overall, these findings suggest that DNMT3a in the hippocampus plays an important role in the acquisition of morphine SA and may be a valid target to prevent the development of morphine addiction.

DNMT3a mediates paclitaxel-induced abnormal expression of LINE-1 by increasing the intragenic methylation

The activation of long interspersed nuclear element-1 (LINE-1) leads to genomic instability, which promotes carcinogenesis and drug resistant. Therefore, exploring the mechanism underlying LINE-1 abnormal activation has the theoretical and clinical significance. DNA methylation is an important way to regulate gene expression. DNMT3a, one member of the DNA methyltransferase family, not only inhibits gene expression by inducing promoter hypermethylation, but also activates gene expression by increasing the intragenic DNA methylation. Our previous studies found that the expression of LINE-1 did not increase significantly in the promoter methylation in breast cancer cells treated with paclitaxel (PTX), a first-line chemotherapeutic drug for breast cancer. Here we explored whether DMNMT3a could directly mediate the drug-induced activation of LINE-1 in breast cancer cells through increasing the LINE-1 intragenic methylation. Our ChIP experiments and methyl analysis showed that treatment of breast cancer cells with PTX not only induced DNMT3a expression, but also promoted the binding of DNMT3a to the inner region of the LINE-1 gene to increase its methylation, resulting in upregulation of LINE-1 expression. Using expression vectors or RNA interference to alter the DNMT3a expression levels in the cells significantly changed the intragenic methylation degree and LINE-1 expression. Moreover, down-regulation of DNMT3a expression effectively inhibited the expression of LINE-1. These results indicate that DNMT3a-mediated intragenic methylation plays an important role in drug-induced abnormal activation of LINE-1, which provides a new idea for understanding the mechanism of abnormal activation of Line-1 induced by chemotherapy drug stress in breast cancer cells.

AGR2 is controlled by DNMT3a-centered signaling module and mediates tumor resistance to 5-Aza in colorectal cancer

Human anterior gradient-2 (AGR2), a member of protein disulfide isomerase (PDI) family, is upregulated in various human cancers and reportedly has oncogenic activities. However, the functional roles of AGR2 and its regulation in colorectal cancer (CRC) remain unclear. Here, we showed that AGR2 promoted CRC tumorigenesis and progression in vitro and in vivo and acted as an independent prognostic factor of poor outcome. AGR2 was negatively regulated by DNA methyltransferase 3a (DNMT3a) through directly methylating AGR2 promoter and by a DNMT3a-SPRY2-miR-194 axis. Moreover, AGR2 mediated the resistance to 5-Aza-2'-deoxycytidine (5-Aza) treatment. Knockdown of AGR2 improved the therapeutic effect of 5-Aza in human CRC xenograft tumor model. Thus, our work supports AGR2's oncogenic role in CRC, reveals DNMT3a-mediated epigenetic modulation on AGR2 promoter, and uncovers a new DNMT3a signaling module controlling expression of AGR2. Upregulated AGR2 offset 5-Aza mediated epigenetic therapy. This work might provide potential targets for clinical anti-cancer therapy.

Altered microRNA, mRNA, and Protein Expression of Neurodegeneration-Related Biomarkers and Their Transcriptional and Epigenetic Modifiers in a Human Tau Transgenic Mouse Model in Response to Developmental Lead Exposure

Amyloid deposits originating from the amyloid-β protein precursor (AβPP) and aggregates of the microtubule associated protein tau (MAPT) are the hallmarks of Alzheimer's disease (AD). Animal studies have demonstrated a link between early life exposure to lead (Pb) and latent overexpression of the AβPP and MAPT genes and their products via epigenetic reprogramming. The present study monitored APP gene and epigenetic mediators and transcription factors known to regulate it. Western blot analysis and quantitative polymerase chain reaction (qPCR) were used to study the mRNA, miRNA, and proteins levels of AβPP, specificity protein 1 (SP1; a transcriptional regulator of amyloid and tau pathway), and epigenetic intermediates namely: DNA methyltransferase (DNMT) 1, DNMT3a and Methyl- CpG protein binding 2 (MeCP2) in the cerebral cortex of transgenic mice (Knock-in for human MAPT). These transgenic mice were developmentally exposed to Pb and the impact on mRNA, miRNA, and protein levels was scrutinized on postnatal days (PND) 20 and 50. The data revealed a consistent inverse relationship between miRNA and protein levels for SP1 and AβPP both in the basal and exposed conditions, which may influence the levels of their corresponding proteins. On the other hand, the relationship between miRNA and protein levels was not correlative for DNMT1 and DNMT3a. MeCP2 miRNA protein levels corresponded only following environmental exposure. These results suggest that developmental exposure to Pb and subsequent AβPP protein levels may be controlled through transcriptional regulators and epigenetic mechanisms that mainly involve miRNA regulation.

Overexpression of miR-450 affects the biological behavior of HepG2 cells by targeting DNMT3a

Purpose

This study was designed to explore the regulation mechanism of miR-450 in the development of hepatocarcinoma, and the effects of overexpression of miR-450 on biological behaviors such as proliferation, migration, and invasion of hepatoma cells.

Methods

HepG2 cells were divided into miR-450 mimics group, miR-450 inhibitor group, miR-450 mimics NC group, miR-450 inhibitor NC group, and blank group. MTT assay was served to measure cell proliferation, and Transwell assay was used to test cell migration and invasion. Additionally, cell cycle was detected by flow cytometry and apoptosis was examined with AnnexinV-PI double staining. After the target gene of miR-450 was predicted by bioinformatics software, Western blot and dual luciferase reporter gene experiment were applied to verify the relationship between miR-450 and target gene.

Results

The MTT and Transwell assay indicated that overexpression of miR-450 inhibited the proliferation, invasion, and migration of HepG2 cells. The flow cytometry analysis showed that overexpression of miR-450 arrested the cell cycle in the G1 phase. Meanwhile, Annexin V-PI double staining assay revealed that overexpression of miR-450 promoted apoptosis of HepG2 cells. However, silencing miR-450 in HepG2 cells promoted proliferation and invasion, and reduced apoptosis. Moreover, we found that DNMT3a was the target gene of miR-450.

Conclusions

miR-450 could inhibit proliferation, invasion, and migration via regulating DNMT3a in hepatocarcinoma cells, which provided a theoretical basis for the treatment of liver cancer.

DNMT3a-triggered downregulation of K2p 1.1 gene in primary sensory neurons contributes to paclitaxel-induced neuropathic pain

Antineoplastic drugs induce dramatic transcriptional changes in dorsal root ganglion (DRG) neurons, which may contribute to chemotherapy-induced neuropathic pain. K_2p 1.1 controls neuronal excitability by setting the resting membrane potential. Here, we report that systemic injection of the chemotherapy agent paclitaxel time-dependently downregulates the expression of K _2p 1.1 mRNA and its coding K_2p 1.1 protein in the DRG neurons. Rescuing this downregulation mitigates the development and maintenance of paclitaxel-induced mechanical allodynia and heat hyperalgesia. Conversely, in the absence of paclitaxel administration, mimicking this downregulation decreases outward potassium current and increases excitability in the DRG neurons, leading to the enhanced responses to mechanical and heat stimuli. Mechanically, the downregulation of DRG K _2p 1.1 mRNA is attributed to paclitaxel-induced increase in DRG DNMT3a, as blocking this increase reverses the paclitaxel-induced the decrease of DRG K_2p 1.1 and mimicking this increase reduces DRG K_2p 1.1 expression. In addition, paclitaxel injection increases the binding of DNMT3a to the K _2p 1.1 gene promoter region and elevates the level of DNA methylation within this region in the DRG. These findings suggest that DNMT3a-triggered downregulation of DRG K_2p 1.1 may contribute to chemotherapy-induced neuropathic pain.

HDAC2 depletion promotes osteosarcoma's stemness both in vitro and in vivo: a study on a putative new target for CSCs directed therapy

Background

Cancer stem cells (CSCs) play a key role in cancer initiation, progression and chemoresistance. Epigenetic alterations have been identified as prominent factors that contribute to the CSCs phenotype. Here, we investigated the effects of the HDAC inhibitor valproic acid (VPA) and the demethylating agent, 5’azacytidine (DAC) on the stem phenotype of MG63 and Saos2 osteosarcoma cell lines.

Methods

Saos2 and MG63 cells were treated with DAC and VPA, alone and in combination. Untreated and treated cells were examined for stemness phenotype by cytometry and real-time PCR. Sarcospheres and colonies formation were also evaluated. Moreover, histone modification and methylation were tested by flow cytomery and western blotting. HDAC2 depleted cells were examined for stemness phenotype and their ability to generate tumors in NOD/SCID IL2R-gamma-0 (NSG) mice. HDAC2 expression on human osteosarcoma tissues was evaluated.

Results

We found that DAC and VPA induce an increased expression of stem markers including CD133, OCT4, SOX2 and NANOG, and an increased ability in sarcospheres and colonies formation efficiency. Interestingly, we showed that DAC and VPA treatment decreased repressive histone markers, while increased the active ones. These histone modifications were also associated with an increase of acetylation of histones H3, a decrease of DNA global methylation, HDAC2 and DNMT3a. Furthermore, HDAC2 silenced-MG63 and Saos2 cells acquired a stem phenotype, and promoted in vivo tumorigenesis. In human osteosarcoma tissues, HDAC2 was strongly expressed in nucleus.

Conclusions

Collectively, our results suggest that VPA and DAC induce an expansion of osteosarcoma CSCs, and we report for the first time that HDAC2 is a key factor regulating both CSCs phenotype and in vivo cancer growth. In conclusion, we have identified HDAC2 as a potential therapeutic target in human osteosarcoma treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0978-x) contains supplementary material, which is available to authorized users.

[Association of DNMT3a's single nucleotide polymorphisms with susceptibility to noise-induced hearing loss in Chinese workers]

OBJECTIVE

To investigate the potential association of DNMT3a's single nucleotide polymorphism with susceptibility to noise-induced hearing loss( NIHL) in Chinese noise-exposed workers.

METHODS

A case-control study was performed, and 998 noise-exposed workers from a chemical fibre factory and an energy company, who underwent occupational health examination in 2015, were enrolled as study subjects. Then, general information and noise exposure of the study subjects were obtained through questionnaire survey and on-site noise detection. According to the result of audiological evaluation, they were divided into case group( n = 498, high-frequency threshold shift >25 dB) and man-matched control group( n = 500, high-frequency threshold shift ≤25 dB). At last, genotyping of DNMT3a rs7590760 was conducted with TaqMan-PCR technique.

RESULTS

In the dominant model, the distribution of rs7590760 genotypes between the case group and the control group was statistically significant( P = 0. 001). The NIHL risk of subjects with CC/CG genotype is 1. 56 times the risk of those carrying GG genotype, with an adjusted OR = 1. 56( 95% CI 1. 22-2. 01). After the noise exposure period and noise exposure intensity were stratified, the adjusted OR values for noise exposure period ≤16 years, > 16 years and noise intensity ≤85, 86-92 and >92 dB were respectively 1. 67( 95% CI 1. 17-2. 38), 1. 52( 95% CI 1. 06-2. 17), 1. 56( 95% CI 1. 06-2. 30), 1. 67( 95% CI 0. 94-2. 99) and 1. 51( 95% CI 1. 01-2. 26).

CONCLUSION

The CC/CG genotype of rs7590760 in DNMT3a gene is a potential risk factor for noise-induced hearing loss in Chinese noise-exposed workers.

Dnmt3a deletion cooperates with the Flt3/ITD mutation to drive leukemogenesis in a murine model

Internal tandem duplications of the juxtamembrane domain of FLT3 (FLT3/ITD) are among the most common mutations in Acute Myeloid Leukemia (AML). Resulting in constitutive activation of the kinase, FLT3/ITD portends a particularly poor prognosis, with reduced overall survival and increased rates of relapse. We previously generated a knock-in mouse, harboring an internal tandem duplication at the endogenous Flt3 locus, which develops a fatal myeloproliferative neoplasm (MPN), but fails to develop acute leukemia, suggesting additional mutations are necessary for transformation. To investigate the potential cooperativity of FLT3/ITD and mutant DNMT3A, we bred a conditional Dnmt3a knockout to a substrain of our Flt3/ITD knock-in mice, and found deletion of Dnmt3a significantly reduced median survival of Flt3^ITD/+ mice in a dose dependent manner. As expected, pIpC treated Flt3^ITD/+ mice solely developed MPN, while Flt3^ITD/+;Dnmt3a^f/f and Flt3^ITD/+;Dnmt3a^f/+ developed a spectrum of neoplasms, including MPN, T-ALL, and AML. Functionally, FLT3/ITD and DNMT3A deletion cooperate to expand LT-HSCs, which exhibit enhanced self-renewal in serial re-plating assays. These results illustrate that DNMT3A loss cooperates with FLT3/ITD to generate hematopoietic neoplasms, including AML. In combination with FLT3/ITD, homozygous Dnmt3a knock-out results in reduced time to disease onset, LT-HSC expansion, and a higher incidence of T-ALL compared with loss of just one allele. The co-occurrence of FLT3 and DNMT3A mutations in AML, as well as subsets of T-ALL, suggests the Flt3^ITD/+;Dnmt3a^f/f model may serve as a valuable resource for delineating effective therapeutic strategies in two clinically relevant contexts.

Epigenetic Targeting of Granulin in Hepatoma Cells by Synthetic CRISPR dCas9 Epi-suppressors

The CRISPR-associated Cas9 system can modulate disease-causing alleles both in vivo and ex vivo, raising the possibility of therapeutic genome editing. In addition to gene targeting, epigenetic modulation by the catalytically inactive dCas9 may also be a potential form of cancer therapy. Granulin (GRN), a potent pluripotent mitogen and growth factor that promotes cancer progression by maintaining self-renewal of hepatic stem cancer cells, is upregulated in hepatoma tissues and is associated with decreased tumor survival in patients with hepatoma. We synthesized a group of dCas9 epi-suppressors to target GRN by tethering the C terminus of dCas9 with three epigenetic suppressor genes: DNMT3a (DNA methyltransferase), EZH2 (histone 3 lysine 27 methyltransferase), and KRAB (the Krüppel-associated box transcriptional repression domain). In conjunction with guide RNAs (gRNAs), the dCas9 epi-suppressors caused significant decreases in GRN mRNA abundance in Hep3B hepatoma cells. These dCas9 epi-suppressors initiated de novo CpG DNA methylation in the GRN promoter, and they produced histone codes that favor gene suppression, including decreased H3K4 methylation, increased H3K9 methylation, and enhanced HP1a binding. Epigenetic knockdown of GRN led to the inhibition of cell proliferation, decreased tumor sphere formation, and reduced cell invasion. These changes were achieved at least partially through the MMP/TIMP pathway. This study thus demonstrates the potential utility of using dCas9 epi-suppressors in the development of epigenetic targeting against tumors.

[Apple polyphenol inhibited the proliferation and migration of breast cancer cell MDA-MB-231 mediated by UHRF1]

OBJECTIVE

To investigate the effects of apple polyphenol on cell proliferation and migration of breast cancer cell line MDA-MB-231, and explore the potential mechanism.

METHODS

The breast cancer cells in the logarithmic phase were treated with 0, 50, 100, 200, 400 and 800 μg/m L of apple polyphenol for 24, 48 and 72 h, then Trypan blue staining was employed to detect cell vitality; CCK8 kit was used to determine cell growth and proliferation; cell migration ability was observed by scratch experiment, and the change of proteins expression level was assessed by Western blot.

RESULTS

Apple polyphenol could content-dependently inhibit breast cancer cell's vitality and proliferation between 0 and 800 μg/m L, decrease the proteins level of ubiquitinlike with PHD and ring finger domain 1( UHRF1) and matrix metalloproteinases-2( MMP2), and the protein levels of DNA methyltransferases 3 a( DNMT3 a) and DNMT3 b, themolecular targets of UHRF1, also decreased. Apple polyphenol inhibition of cell 's migration was more significant between 400 and 800 μg/mL.

CONCLUSION

Apple polyphenol inhibited the vitality, cell growth and proliferation, and migration of breast cancer cells MDA-MB-231 by decreasing the proteins expression of UHRF1 and MMP2, and the downstream targets of UHRF1, DNMT3 a and DNMT3 b, also decreased.

The molecular dynamics of long noncoding RNA control of transcription in PTEN and its pseudogene

RNA has been found to interact with chromatin and modulate gene transcription. In human cells, little is known about how long noncoding RNAs (lncRNAs) interact with target loci in the context of chromatin. We find here, using the phosphatase and tensin homolog (PTEN) pseudogene as a model system, that antisense lncRNAs interact first with a 5' UTR-containing promoter-spanning transcript, which is then followed by the recruitment of DNA methyltransferase 3a (DNMT3a), ultimately resulting in the transcriptional and epigenetic control of gene expression. Moreover, we find that the lncRNA and promoter-spanning transcript interaction are based on a combination of structural and sequence components of the antisense lncRNA. These observations suggest, on the basis of this one example, that evolutionary pressures may be placed on RNA structure more so than sequence conservation. Collectively, the observations presented here suggest a much more complex and vibrant RNA regulatory world may be operative in the regulation of gene expression.

[Effects of dietary monosodium-glutamate on gene expression]

INTRODUCTION

Nowadays, the food industry more often uses different type of additives during the food production.

AIM

Our aim was to examine the monosodium-glutamate's effect (in animal experiment) on DNA-methyltransferases in gene expression patterns of mRNA levels.

MATERIALS AND METHOD

In the investigation we used 24 (n=24) CD1 type female mice. The animals were fed with different equivalent human doses of the tested substance. After autopsy, mRNA was isolated from different tissues (lung, liver, kidney, spleen). DNMT1, DNMT3A and DNMT3B levels were determined by Quantitative Real-Time PCR.

RESULTS

DNMT1 significantly suppressed the gene expression in all the three treated groups (p<0.05). The DNMT3A expression patterns showed significant decreasing tendency in the 1. and 2. treated groups of the lung tissue (p<0,05) and 1, 2, 3. groups of liver and kidney tissues (p<0,05).

CONCLUSIONS

Our results shows that the monosodium glutamate, suppressed the DNMT1 and DNMT3A gene expression - on mRNA levels of several organs - in mice. It can be a similar chemopreventive effect to epigallo-catechin-gallate's, curcumin's, genistein's, likopine's and rezveratrol's effects. In this case it can be possible that the MSG has anticarcinogenic effects. Orv. Hetil., 2017, 158(10), 380-385.

Methylation of Septin9 mediated by DNMT3a enhances hepatic stellate cells activation and liver fibrogenesis

Liver fibrosis, resulting from chronic and persistent injury to the liver, is a worldwide health problem. Advanced liver fibrosis results in cirrhosis, liver failure and even hepatocellular cancer (HCC), often eventually requiring liver transplantation, poses a huge health burden on the global community. However, the specific pathogenesis of liver fibrosis remains not fully understood. Numerous basic and clinical studies have provided evidence that epigenetic modifications, especially DNA methylation, might contribute to the activation of hepatic stellate cells (HSCs), the pivotal cell type responsible for the fibrous scar in liver. Here, reduced representation bisulfite sequencing (RRBS) and bisulfite pyrosequencing PCR (BSP) analysis identified hypermethylation status of Septin9 (Sept9) gene in liver fibrogenesis. Sept9 protein was dramatically decreased in livers of CCl4-treated mice and immortalized HSC-T6 cells exposed to TGF-β1. Nevertheless, the suppression of Sept9 could be blocked by DNMT3a-siRNA and DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-azadC). Overexpressed Sept9 attenuated TGF-β1-induced expression of myofibroblast markers α-SMA and Col1a1, accompanied by up-regulation of cell apoptosis-related proteins. Conversely, RNAi-mediated silencing of Sept9 enhanced accumulation of extracellular matrix. These observations suggested that Sept9 contributed to alleviate liver fibrosis might partially through promoting activated HSCs apoptosis and this anti-fibrogenesis effect might be blocked by DNMT-3a mediated methylation of Sept9. Therefore, pharmacological agents that inhibit Sept9 methylation and increase its expression could be considered as valuable treatments for liver fibrosis.

Increased Set1 binding at the promoter induces aberrant epigenetic alterations and up-regulates cyclic adenosine 5'-monophosphate response element modulator alpha in systemic lupus erythematosus

BACKGROUND

Up-regulated cyclic adenosine 5'-monophosphate response element modulator α (CREMα) which can inhibit IL-2 and induce IL-17A in T cells plays a critical role in the pathogenesis of systemic lupus erythematosus (SLE). This research aimed to investigate the mechanisms regulating CREMα expression in SLE.

RESULTS

From the chromatin immunoprecipitation (ChIP) microarray data, we found a sharply increased H3 lysine 4 trimethylation (H3K4me3) amount at the CREMα promoter in SLE CD4+ T cells compared to controls. Then, by ChIP and real-time PCR, we confirmed this result. Moreover, H3K4me3 amount at the promoter was positively correlated with CREMα mRNA level in SLE CD4+ T cells. In addition, a striking increase was observed in SET domain containing 1 (Set1) enrichment, but no marked change in mixed-lineage leukemia 1 (MLL1) enrichment at the CREMα promoter in SLE CD4+ T cells. We also proved Set1 enrichment was positively correlated with both H3K4me3 amount at the CREMα promoter and CREMα mRNA level in SLE CD4+ T cells. Knocking down Set1 with siRNA in SLE CD4+ T cells decreased Set1 and H3K4me3 enrichments, and elevated the levels of DNMT3a and DNA methylation, while the amounts of H3 acetylation (H3ac) and H4 acetylation (H4ac) didn't alter greatly at the CREMα promoter. All these changes inhibited the expression of CREMα, then augmented IL-2 and down-modulated IL-17A productions. Subsequently, we observed that DNA methyltransferase (DNMT) 3a enrichment at the CREMα promoter was down-regulated significantly in SLE CD4+ T cells, and H3K4me3 amount was negatively correlated with both DNA methylation level and DNMT3a enrichment at the CREMα promoter in SLE CD4+ T cells.

CONCLUSIONS

In SLE CD4+ T cells, increased Set1 enrichment up-regulates H3K4me3 amount at the CREMα promoter, which antagonizes DNMT3a and suppresses DNA methylation within this region. All these factors induce CREMα overexpression, consequently result in IL-2 under-expression and IL-17A overproduction, and contribute to SLE at last. Our findings provide a novel approach in SLE treatment.

Transforming Growth Factor-β1 Increases DNA Methyltransferase 1 and 3a Expression through Distinct Post-transcriptional Mechanisms in Lung Fibroblasts

DNA methylation is a fundamental epigenetic mark that plays a critical role in differentiation and is mediated by the actions of DNA methyltransferases (DNMTs). TGF-β1 is one of the most potent inducers of fibroblast differentiation, and although many of its actions on fibroblasts are well described, the ability of TGF-β1 to modulate DNA methylation in mesenchymal cells is less clear. Here, we examine the ability of TGF-β1 to modulate the expression of various DNMTs in primary lung fibroblasts (CCL210). TGF-β1 increased the protein expression, but not RNA levels, of both DNMT1 and DNMT3a. The increases in DNMT1 and DNMT3a were dependent on TGF-β1 activation of focal adhesion kinase and PI3K/Akt. Activation of mammalian target of rapamycin complex 1 by Akt resulted in increased protein translation of DNMT3a. In contrast, the increase in DNMT1 by TGF-β1 was not dependent on new protein synthesis and instead was due to decreased protein degradation. TGF-β1 treatment led to the phosphorylation and inactivation of glycogen synthase kinase-3β, which resulted in inhibition of DNMT1 ubiquitination and proteosomal degradation. The phosphorylation and inactivation of glycogen synthase kinase-3β was dependent on mammalian target of rapamycin complex 1. These results demonstrate that TGF-β1 increases expression of DNMT1 and DNMT3a through different post-transcriptional mechanisms. Because DNA methylation is critical to many processes including development and differentiation, for which TGF-β1 is known to be crucial, the ability of TGF-β1 to increase expression of both DNMT1 and DNMT3a demonstrates a novel means by which TGF-β1 may regulate DNA methylation in these cells.

DNMT3a expression pattern and its prognostic value in lung adenocarcinoma

OBJECTIVES

DNA methyltransferases (DNMTs) are an important part of the methylation pathway that is highly correlated with the pathophysiology of cancers. Several studies have reported overexpression of DNMTs in human lung cancer, but none have compared the expression pattern to pathological features. In this study, we clarified the association of DNMT3a expression pattern with pathological features and prognosis of lung adenocarcinoma.

MATERIALS AND METHODS

135 cases of surgically resected lung adenocarcinoma specimens were used for DNMT3a immunohistochemistry (IHC). IHC score was determined by counting the number of positive nuclei. The ROC curve was drawn to determine the best cut-off point of the score; this was set at 57.5. Western blot also implemented and confirmed the specificity of the antibody. Correlations between expression pattern and clinicopathological features and prognosis were analyzed using chi-squared method and Cox proportional hazards model respectively.

RESULT

Seventy-nine of the 135 cases (58.5%) showed strong positive reactivity to anti-DNMT3a. In terms of histological subtypes, among invasive lung adenocarcinomas 41 out of 53 lepidic adenocarcinomas (77%) were strongly positive, while among the other histological subtypes only 23 out of 66 cases (34.8%) showed a positive reaction. Among non-invasive lung adenocarcinomas 15 out of 16 cases (93.8%) were strongly positive. The level of DNMT3a expression was associated with patient outcome, and patients with weak expression of DNMT3a had a poorer outcome than those with strong expression. Multivariate analysis also indicated that DNMT3a is an independent prognostic marker in lung adenocarcinoma.

CONCLUSION

Our results indicate that DNMT3a expression in lung adenocarcinoma is associated with the histologically non-invasive type and lepidic subtype, and a favorable prognosis. We also showed that DNMT3a expression is an independent prognostic marker in lung adenocarcinoma. Since lack of DNMT3a is thought to facilitate tumor progression, DNMT3a might be clinically applicable as an indicator of favorable prognosis.

Hypoxia-induced endothelial-mesenchymal transition is associated with RASAL1 promoter hypermethylation in human coronary endothelial cells

Cardiac fibrosis is integral in chronic heart disease, and one of the cellular processes contributing to cardiac fibrosis is endothelial-to-mesenchymal transition (EndMT). We recently found that hypoxia efficiently induces human coronary artery endothelial cells (HCAEC) to undergo EndMT through a hypoxia inducible factor-1α (HIF1α)-dependent pathway. Promoter hypermethylation of Ras-Gap-like protein 1 (RASAL1) has also been recently associated with EndMT progression and cardiac fibrosis. Our findings suggest that HIF1α and transforming growth factor (TGF)/SMAD signalling pathways synergistically regulate hypoxia-induced EndMT through both DNMT3a-mediated hypermethylation of RASAL1 promoter and direct SNAIL induction. The findings indicate that multiple cascades may be activated simultaneously to mediate hypoxia-induced EndMT.

Chronic hypoxia facilitates Alzheimer's disease through demethylation of γ-secretase by downregulating DNA methyltransferase 3b

INTRODUCTION

Environmental factors and epigenetic mechanisms are believed to contribute to Alzheimer's disease (AD). We previously documented that prenatal hypoxia aggravated the cognitive impairment and neuropathology in offspring mice. Here, we investigate the chronic hypoxia-induced epigenetic modifications in AD.

METHODS

The 3-month-old APP(swe)/PS1(dE9) mice were exposed to hypoxic environment 6 hour/day for 30 days, followed by learning and memory tests and biochemical and neuropathology measurement at the age of 4, 6, and 9 months.

RESULTS

We found hypoxia exaggerated the neuropathology and cognitive impairment in AD mice. Chronic hypoxia induced demethylation on genomic DNA and decreased the expression of DNA methyltransferase 3b (DNMT3b) in vivo. We further found that DNMTs inhibition elevated the protein levels of amyloid precursor protein, β- and γ-secretases, whereas overexpression of DNMT3b suppressed the levels of them in vitro.

DISCUSSION

Our study suggests chronic hypoxia can aggravate AD progression through demethylation of genes encoding γ-secretase components by downregulation of DNMT3b.

Neonatal hyperoxia induces alterations in neurotrophin gene expression

Each year in the United States, nearly 500,000 infants a year are born prematurely. Babies born before 35 weeks gestation are often placed on ventilators and/or given supplemental oxygen. This increase in oxygen, while critical for survival, can cause long-term damage to lungs, retinas and brains. In particular, hyperoxia causes apoptosis in neurons and alters glial activity. Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) are members of the neurotrophin family of proteins that function to promote the growth, differentiation and development of the nervous system. We hypothesized that hyperoxia can alter the regulation of these genes and by doing so adversely affect the development of the brain. We predicted that mice exposed to hyperoxic conditions would have differences in BDNF and GDNF mRNA expression and relative level of methylated promoter regions coinciding with differences in the relative levels of DNMT1 and DNMT3a mRNA expression. To test this hypothesis, newborn C57Bl/6 mice and their littermates were placed in hyperoxic or normoxic conditions from postnatal day 7 to 12. There were significant decreases in BDNF mRNA expression in the prefrontal cortex following hyperoxia, but a significant increase in the isocortex. GDNF mRNA expression was significantly increased in both the isocortex and prefrontal cortex following hyperoxia. DNMT1 mRNA expression was significantly decreased in the isocortex but significantly increased in the prefrontal following hyperoxia. Together these data suggest that short-term exposure to hyperoxic conditions can affect the regulation and expression of BDNF and GDNF potentially leading to alterations in neural development.

miR-182 induces cervical cancer cell apoptosis through inhibiting the expression of DNMT3a

Cervical cancer is the second most common and malignant tumor among women worldwide. However, the effective therapies for this deadly disease are limited because the elaborate molecular mechanism of progress of cervical cancer remains largely unknown. In present study, we not only determine the miR-182 as an anticancer miRNA molecule but also provide the mechanistic link between miR-182 and its anticancer activity. Primarily, the expression of miR-182 is significantly down-regulated in cervical tumor in contrast to normal cervical tissue, and then miR-182 mimic-treated cell presents reduction of cell proliferation and promoting apoptosis. During this process, DNA methyltransferase 3a (DNMT3a) expression is markedly decreased, thereby likely contributing to miR-182-induced apoptosis. Consistently, over-expression of DNMT3a inhibits the miR-182-induced apoptosis, and inhibition of DNMT3a promotes cervical cancer cell apoptosis, which further demonstrated that DNMT3a involved in cervix carcinogenesis. Collectively, we have revealed a valuable mechanism by which down-regulation of DNMT3a contributes to the miR-182-induced cervical cancer cell apoptosis, which raise a becoming potential that miR-182 administration or inhibition of DNMT3a expression may be the underlying strategies for therapeutic intervention in cervical carcinoma.