Editorial-Role of DNA Methyltransferases in the Epigenome

Evaluation of epigenetic (HDAC, DNMT) and pain (Gad65, TGF) factors following photobiomodulation therapy in a neuropathic pain model

Photobiomodulation therapy (PBMT) is converted to the most common analgesic treatment before the whole mechanism is yet to be discovered. This study for the first time was designed to investigate alternations of epigenetic factors after pain and PBMT. The CCI model was chosen to induce pain. Pain evaluation tests including plantar, acetone, von Frey, and pinch were done weekly. Then spinal cord tissue was isolated for evaluating mRNA expression of DNMT3a, HDAC1, and NRSF using RT-qPCR method, and protein expression factors of HDAC2 and DNMT3a using western blotting. GAD65 and TGF-β proteins were assessed by the IHC method. PBMT increased the pain threshold up to the point where it roughly met the pain threshold of the control group. After three weeks of treatment, both PBMT protocols demonstrated a reduction in allodynia and hyperalgesia. While some molecules, such as TGF-β and Gad65, increased following PBMT, we observed no inhibition of NRSF, HDAC1, and DNMT3a expression despite implementing two different protocols.

Pathophysiology of Circulating Biomarkers and Relationship With Vascular Aging: A Review of the Literature From VascAgeNet Group on Circulating Biomarkers, European Cooperation in Science and Technology Action 18216

Impairment of the arteries is a product of sustained exposure to various deleterious factors and progresses with time; a phenomenon inherent to vascular aging. Oxidative stress, inflammation, the accumulation of harmful agents in high cardiovascular risk conditions, changes to the extracellular matrix, and/or alterations of the epigenetic modification of molecules, are all vital pathophysiological processes proven to contribute to vascular aging, and also lead to changes in levels of associated circulating molecules. Many of these molecules are consequently recognized as markers of vascular impairment and accelerated vascular aging in clinical and research settings, however, for these molecules to be classified as biomarkers of vascular aging, further criteria must be met. In this paper, we conducted a scoping literature review identifying thirty of the most important, and eight less important, biomarkers of vascular aging. Herein, we overview a selection of the most important molecules connected with the above-mentioned pathological conditions and study their usefulness as circulating biomarkers of vascular aging.

DNA methyltransferase 1 inhibits O6-methylguanine-DNAmethyl-transferase-mediated cell growth and metastasis of hypopharyngeal squamous carcinoma

OBJECTIVE

To explore the role of DNA methyltransferase 1 (DNMT1) in development and progression of hypopharyngeal squamous carcinoma.

DESIGN

A total of 32 hypopharyngeal squamous carcinoma biopsy samples and 20 normal tissue specimens were collected. Immunohistochemical staining, quantitative real-time polymerase chain reaction, and Western blot were performed for expression analysis. The mRNA and protein expression in the specimens and subcellular localization were analyzed. hypopharyngeal squamous carcinoma cells (FaDu) were used for small interfering RNA of DNMT1, and proliferation, cell cycle, and apoptosis were determined in the transfected cells. Furthermore, metastatic ability and methylation status of O⁶-methylguanine-DNAmethyl-transferase (MGMT) promoter was assessed.

RESULTS

Our results showed that DNMT1 was overexpressed, while MGMT was down expressed in hypopharyngeal squamous carcinoma. DNMT1 overexpression and MGMT down expression were significantly associated with poorly differentiated tumors, lymph node metastasis, and clinical stage. DNMT1 and MGMT were majorly distributed in the nucleus. Furthermore, knockdown of DNMT1 inhibited proliferation and metastasis, induced apoptosis and G1 phase arrest in FaDu cells, and upregulated MGMT expression to reverse methylation status of MGMT promoter.

CONCLUSIONS

This study for the first time demonstrated the clinical value and the role of DNMT1 and MGMT in the biological function of hypopharyngeal squamous carcinoma. This work suggested that DNMT1 might serve as a potential therapeutic target for patients with hypopharyngeal squamous carcinoma.

Early-life nutrition and metabolic disorders in later life: a new perspective on energy metabolism

Type 2 diabetes mellitus and metabolic disorders have become an epidemic globally. However, the pathogenesis remains largely unclear and the prevention and treatment are still limited. In addition to environmental factors during adulthood, early life is the critical developmental window with high tissue plasticity, which might be modified by external environmental cues. Substantial evidence has demonstrated the vital role of early-life nutrition in programming the metabolic disorders in later life. In this review, we aim to overview the concepts of fetal programming and investigate the effects of early-life nutrition on energy metabolism in later life and the potential epigenetic mechanism. The related studies published on PubMed database up to March 2020 were included. The results showed that both maternal overnutrition and undernutrition increased the riskes of metabolic disorders in offspring and epigenetic modifications, including DNA methylation, miRNAs, and histone modification, might be the vital mediators. The beneficial effects of early-life lifestyle modifications as well as dietary and nutritional interventions on these deleterious metabolic remolding were initially observed. Overall, characterizing the early-life malnutrition that reshapes metabolic disease trajectories may yield novel targets for early prevention and intervention and provide a new point of view to the energy metabolism.

Decoding the Genetic Alterations in Genes of DNMT Family (DNA Methyl-Transferase) and their Association with Head and Neck Squamous Cell Carcinoma

OBJECTIVE

Epigenetic modifications are gaining focus due to their indirect association with tumorigenesis. DNA methylation plays a prime role in regulation of gene expression. Any aberrations in this gene family may lead to chromosomal instability and increased magnitude of tumour progression. In line with the above fact, the present study has been designed to identify genetic alterations in the genes of the DNMT (DNA methyl-transferase) family among head and neck squamous cell carcinoma patients (HNSCC).

METHODS

The present study follows an observational design employing computational tools for analysis. The TCGA-Firehose Legacy data was assessed using the cBioportal database. The dataset comprised of 530 samples from HNSCC patients which were assessed for genetic alterations in the DNMT family. Furthermore, the protein stability analysis and pathogenicity of the mutations were assessed using I-Mutant Suite and PROVEAN tools.

RESULTS

Almost all genes of the DNMT family harboured gene amplification. The TRDMT1 and DNMT3L genes showed deep deletions. Apart from these several non-synonymous, truncating and splice-site mutations were also documented. Protein stability and pathogenicity analysis revealed that majority of the mutations were found to decrease the stability and impose pathogenicity. Upon probing for reported mutations using gnomAD database, around six reference single nucleotide polymorphisms were identified which were found to exhibit a minor allele frequency less than 0.01.

CONCLUSIONS

Screening of an exhaustive collection of patient's samples could provide immense knowledge about the disease pathogenesis and identification of therapeutic leads. The variants identified in the present study could be used as diagnostic markers. However, further experimental analysis through genotyping assay is warranted to validate the present findings.
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Prenatal stress induced chromatin remodeling and risk of psychopathology in adulthood

New insights into the pathophysiology of psychiatric disorders suggest the existence of a complex interplay between genetics and environment. This notion is supported by evidence suggesting that exposure to stress during pregnancy exerts profound effects on the neurodevelopment and behavior of the offspring and predisposes them to psychiatric disorders later in life. Accumulated evidence suggests that vulnerability to psychiatric disorders may result from permanent negative effects of long-term changes in synaptic plasticity due to altered epigenetic mechanisms (histone modifications and DNA methylation) that lead to condensed chromatin architecture, thereby decreasing the expression of candidate genes during early brain development. In this chapter, we have summarized the literature of clinical studies on psychiatric disorders induced by maternal stress during pregnancy. We also discussed the epigenetic alterations of gene regulations induced by prenatal stress. Because the clinical manifestations of psychiatric disorders are complex, it is obvious that the biological progression of these diseases cannot be studied only in postmortem brains of patients and the use of animal models is required. Therefore, in this chapter, we have introduced a well-established mouse model of prenatal stress (PRS) generated in restrained pregnant dams. The behavioral phenotypes of the offspring (PRS mice) born to the stressed dam and underlying epigenetic changes in key molecules related to synaptic activity were described and highlighted. PRS mice may serve as a useful model for investigating the pathogenesis of psychiatric disorders and may be a useful tool for screening for the potential compounds that may normalize aberrant epigenetic mechanisms induced by prenatal stress.

DNA Methylation May be Involved in the Analgesic Effect of Hyperbaric Oxygen via Regulating FUNDC1

Background

Neuropathic pain (NP) is a type of chronic pain which lacks predictable, effective, and safe therapeutic options. We investigated the role of hyperbaric oxygen (HBO) in expression of FUN14 domain-containing 1 (FUNDC1), which is associated with DNA methylation.

Methods

We randomly divided rats into four groups: sham operation (S), S + HBO, chronic constriction injury (CCI), and CCI + HBO. Lumbar (L)4 and L5 dorsal root ganglia (DRGs) were used to assess expression of DNA methyltransferase (DNMT)1, DNMT3a, and DNMT3b by western blotting and RT-PCR. Pain-related behaviors were evaluated using mechanical withdrawal threshold and thermal withdrawal latency analysis. Western blotting was also used to assess expression of FUNDC1, BCL2, and adenovirus E1B19 kDa-interacting protein 3-like (NIX) and BCL2 and adenovirus E1B19 kDa-interacting protein3 (BNIP3). And we also examined the changes of FUNDC1 with immunofluorescence. Nonnucleoside DNA methyltransferase inhibitor RG108 was administered prior to CCI. The pain-related behavior and western blotting changes were examined in all groups.

Results

DNMT3a expression was higher on day 14 after CCI. HBO downregulated DNMT3a mRNA and protein expression, but not those of DNMT1 and DNMT3b. HBO increased pain-related behavior significantly, while it was down-regulated by RG108. In HBO groups, FUNDC1, NIX, and BNIP3 expression was upregulated more significantly than in the CCI group. In addition, FUNDC1 protein colocalized with NeuN and rarely with glutamine synthetase. However, expression was reduced when RG108 was administered. Immunofluorescence showed that FUNDC1 was upregulated after HBO treatment.

Conclusion

Our findings suggest that DNA methylation is involved in the analgesic effect of HBO via the regulation of FUNDC1.