Reduced mRNA and Protein Expression Levels of Tet Methylcytosine Dioxygenase 3 in Endothelial Progenitor Cells of Patients of Type 2 Diabetes With Peripheral Artery Disease

The role of transcription factor Ap1 in the activation of the Nrf2/ARE pathway through TET1 in diabetic nephropathy

TET1 mediates demethylation in tumors, but its role in diabetic nephropathy (DN), a prevalent diabetic complication, is unclear. We attempted to probe the possible mechanism of TET1 in DN. A DN rat model was established and verified by marker detection and histopathological observation. The in vitro model was established on human mesangial cells (HMCs) induced by high glucose (HG), and verified by evaluation of fibrosis and inflammation. The differentially expressed mRNA was screened out by microarray analysis. The most differentially expressed mRNA (TET1) was reduced in DN rats and HG-HMCs. The upstream and downstream factors of TET1 were verified, and their roles in DN were analyzed by gain- and loss-function assays. TET1 was decreased in DN rats and HG-HMCs. High expression of TET1 decreased biochemical indexes and renal injury of DN rats and hampered the activity, fibrosis, and inflammation of HG-HMCs. Ap1 lowered TET1 expression, and enhanced inflammation in HG-HMCs, and accentuated renal injury in DN rats. TET1 overexpression inhibited the effect of Ap1 on DN. TET1 promoted the transcription of Nrf2. The Ap1/TET1 axis mediated the Nrf2/ARE pathway activity. Overall, TET1 overexpression weakened the inhibitory effect of Ap1 on the Nrf2/ARE pathway, thus alleviating inflammation and renal injury in DN.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection: Triggering a Lethal Fight to Keep Control of the Ten-Eleven Translocase (TET)-Associated DNA Demethylation?

The extended and diverse interference of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in multiple host functions and the diverse associated symptoms implicate its involvement in fundamental cellular regulatory processes. The activity of ten-eleven translocase 2 (TET2) responsible for selective DNA demethylation, has been recently identified as a regulator of endogenous virus inactivation and viral invasion, possibly by proteasomal deregulation of the TET2/TET3 activities. In a recent report, we presented a detailed list of factors that can be affected by TET activity, including recognition of zinc finger protein binding sites and bimodal promoters, by enhancing the flexibility of adjacent sequences. In this review, we summarize the TET-associated processes and factors that could account for SARS-CoV-2 diverse symptoms. Moreover, we provide a correlation for the observed virus-induced symptoms that have been previously associated with TET activities by in vitro and in vitro studies. These include early hypoxia, neuronal regulation, smell and taste development, liver, intestinal, and cardiomyocyte differentiation. Finally, we propose that the high mortality of SARS-CoV-2 among adult patients, the different clinical symptoms of adults compared to children, the higher risk of patients with metabolic deregulation, and the low mortality rates among women can all be accounted for by the complex balance of the three enzymes with TET activity, which is developmentally regulated. This activity is age-dependent, related to telomere homeostasis and integrity, and associated with X chromosome inactivation via (de)regulation of the responsible XIST gene expression.

Epigenetic factors in atherosclerosis: DNA methylation, folic acid metabolism, and intestinal microbiota

Atherosclerosis is a complex disease, influenced by both genetic and non-genetic factors. The most important epigenetic mechanism in the pathogenesis of atherosclerosis is DNA methylation, which involves modification of the gene without changes in the gene sequence. Nutrients involved in one-carbon metabolism interact to regulate DNA methylation, especially folic acid and B vitamins. Deficiencies in folic acid and other nutrients, such as vitamins B6 and B12, can increase homocysteine levels, induce endothelial dysfunction, and accelerate atherosclerotic pathological processes. Supplemented nutrients can improve DNA methylation status, reduce levels of inflammatory factors, and delay the process of atherosclerosis. In this review, the influence of intestinal flora on folate metabolism and epigenetics is also considered.

Epigenetic Regulation of Endothelial Cell Function by Nucleic Acid Methylation in Cardiac Homeostasis and Disease

Pathological remodelling of the myocardium, including inflammation, fibrosis and hypertrophy, in response to acute or chronic injury is central in the development and progression of heart failure (HF). While both resident and infiltrating cardiac cells are implicated in these pathophysiological processes, recent evidence has suggested that endothelial cells (ECs) may be the principal cell type responsible for orchestrating pathological changes in the failing heart. Epigenetic modification of nucleic acids, including DNA, and more recently RNA, by methylation is essential for physiological development due to their critical regulation of cellular gene expression. As accumulating evidence has highlighted altered patterns of DNA and RNA methylation in HF at both the global and individual gene levels, much effort has been directed towards defining the precise role of such cell-specific epigenetic changes in the context of HF. Considering the increasingly apparent crucial role that ECs play in cardiac homeostasis and disease, this article will specifically focus on nucleic acid methylation (both DNA and RNA) in the failing heart, emphasising the key influence of these epigenetic mechanisms in governing EC function. This review summarises current understanding of DNA and RNA methylation alterations in HF, along with their specific role in regulating EC function in response to stress (e.g. hyperglycaemia, hypoxia). Improved appreciation of this important research area will aid in further implicating dysfunctional ECs in HF pathogenesis, whilst informing development of EC-targeted strategies and advancing potential translation of epigenetic-based therapies for specific targeting of pathological cardiac remodelling in HF.