Fibrosis-the tale of H3K27 histone methyltransferases and demethylases

Epigenetic targets and their inhibitors in the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease characterized by fibroblast proliferation, excessive extracellular matrix buildup, inflammation, and tissue damage, resulting in respiratory failure and death. Recent studies suggest that impaired interactions among epithelial, mesenchymal, immune, and endothelial cells play a key role in IPF development. Advances in bioinformatics have also linked epigenetics, which bridges gene expression and environmental factors, to IPF. Despite the incomplete understanding of the pathogenic mechanisms underlying IPF, recent preclinical studies have identified several novel epigenetic therapeutic targets, including DNMT, EZH2, G9a/GLP, PRMT1/7, KDM6B, HDAC, CBP/p300, BRD4, METTL3, FTO, and ALKBH5, along with potential small-molecule inhibitors relevant for its treatment. This review explores the pathogenesis of IPF, emphasizing epigenetic therapeutic targets and potential small molecule drugs. It also analyzes the structure-activity relationships of these epigenetic drugs and summarizes their biological activities. The objective is to advance the development of innovative epigenetic therapies for IPF.

Epigenetic Symphony in Diffuse Large B-Cell Lymphoma: Orchestrating the Tumor Microenvironment

DLBCL is a testament to the complexity of nature. It is characterized by remarkable diversity in its molecular and pathological subtypes and clinical manifestations. Despite the strides made in DLBCL treatment and the introduction of innovative drugs, around one-third of patients face a relapse or develop refractory disease. Recent findings over the past ten years have highlighted the critical interplay between the evolution of DLBCL and various epigenetic mechanisms, including chromatin remodeling, DNA methylation, histone modifications, and the regulatory roles of non-coding RNAs. These epigenetic alterations are integral to the pathways of oncogenesis, tumor progression, and the development of therapeutic resistance. In the past decade, the identification of dysregulated epigenetic mechanisms in lymphomas has paved the way for an exciting field of epigenetic therapies. Crucially, these epigenetic transformations span beyond tumor cells to include the sophisticated network within the tumor microenvironment (TME). While the exploration of epigenetic dysregulation in lymphoma cells is thriving, the mechanisms affecting the functions of immune cells in the TME invite further investigation. This review is dedicated to weaving together the narrative of epigenetic alterations impacting both lymphoma cells with a focus on their infiltrating immune companions.

Epigenetic regulation of macrophage function in kidney disease: New perspective on the interaction between epigenetics and immune modulation

The interaction between renal intrinsic cells and macrophages plays a crucial role in the onset and progression of kidney diseases. In recent years, epigenetic mechanisms such as DNA methylation, histone modification, and non-coding RNA regulation have become essential windows for understanding these processes. This review focuses on how renal intrinsic cells (including tubular epithelial cells, podocytes, and endothelial cells), renal cancer cells, and mesenchymal stem cells influence the function and polarization status of macrophages through their own epigenetic alterations, and how the epigenetic regulation of macrophages themselves responds to kidney damage, thus participating in renal inflammation, fibrosis, and repair. Moreover, therapeutic studies targeting these epigenetic interaction mechanisms have found that the application of histone deacetylase inhibitors, histone methyltransferase inhibitors, various nanomaterials, and locked nucleic acids against non-coding RNA have positive effects on the treatment of multiple kidney diseases. This review summarizes the latest research advancements in these epigenetic regulatory mechanisms and therapies, providing a theoretical foundation for further elucidating the pathogenesis of kidney diseases and the development of novel therapeutic strategies.

KDM6B-Mediated HADHA Demethylation/Lactylation Regulates Cementogenesis

Cementum, a bone-like tissue, is an essential component of periodontium, and periodontitis can lead to degenerative changes in the cementum, eventually resulting in tooth loss. The therapeutic strategy for advanced periodontitis is to achieve periodontal regeneration, of which cementum regeneration is a key criterion. Cementoblasts are responsible for cementogenesis, and their mineralization counts in cementum regeneration. However, research is still limited. Thus, novel treatment targets are required. The expression levels of lysine (K)-specific demethylase 6B (KDM6B), fatty acid oxidation (FAO), and cementogenic markers were detected by quantitative polymerase chain reaction, Western blot, immunofluorescence, and immunohistochemical assays. FAO levels were analyzed by assay kit. In vivo, injection of GSK-J4 into mice detected the influence of KDM6B on cementum formation. Chromatin immunoprecipitation sequencing, transcriptomic RNA sequencing, subsequent chromatin immunoprecipitation-quantitative polymerase chain reaction and overexpression of HADHA (hydroxyacyl-coA dehydrogenase trifunctional multienzyme complex subunit alpha) elucidated the KDM6B-Hadha axis. Global lactylation was detected by Western blot. Lactylation proteomics clarified the modified sites of HADHA. Mutating these sites and applying coimmunoprecipitation confirmed their significance. Knockdown of Kdm6b was utilized to assess its regulation on the lactylation of HADHA, FAO, and mineralization levels. FAO and KDM6B expression was elevated during cementoblast mineralization. KDM6B targeted Hadha and activated its transcription, thereby increasing FAO levels and promoting mineralization. Lactylation occurred in the process of mineralization, and KDM6B could regulate the lactylation of HADHA to promote FAO and mineralization. Overexpression of Hadha and the addition of lactate sodium could rescue the inhibition of mineralization by knockdown of Kdm6b. In summary, during cementoblast mineralization, KDM6B regulates HADHA by mediating histone demethylation and lactylation, thereby upregulating FAO and thus promoting mineralization.

EZH2-Mediated H3K27 Trimethylation in the Liver of Mice Is an Early Epigenetic Event Induced by High-Fat Diet Exposure

BACKGROUND/OBJECTIVES

Methyltransferase EZH2-mediated H3K27me3 is involved in liver inflammation and fibrosis, but its role in hepatic metabolic derangements is not yet clearly defined. We investigated if a high-fat diet (HFD) induced early changes in EZH2 expression and H3K27 me3 in the liver of mice.

METHODS

Five-week-old mice were fed an HFD or a low-fat diet (Control) for 2 weeks (2 W) or 8 weeks (8 W). Body weight was recorded weekly. Glycemia and oral glucose tolerance were assessed at baseline and after 2 W-8 W. Finally, livers were collected for further analysis.

RESULTS

As expected, mice that received 8 W HFD showed an increase in body weight, glycemia, and liver steatosis and an impairment in glucose tolerance; no alterations were observed in 2 W HFD mice. Eight weeks of HFD caused hepatic EZH2 nuclear localization and increased H3 K27me3; surprisingly, the same alterations occurred in 2 W HFD mice livers, even before overweight onset. We demonstrated that selective EZH2 inhibition reduced H3K27me3 and counteracted lipid accumulation in HUH-7 cells upon palmitic acid treatment.

CONCLUSIONS

In conclusion, we point to EZH2/H3K27me3 as an early epigenetic event occurring in fatty-acid-challenged livers both in vivo and in vitro, thus establishing EZH2 as a potential pharmacological target for metabolic derangements.

Epigenetic Regulation of Autophagy in Bone Metabolism

The skeletal system is crucial for supporting bodily functions, protecting vital organs, facilitating hematopoiesis, and storing essential minerals. Skeletal homeostasis, which includes aspects such as bone density, structural integrity, and regenerative processes, is essential for normal skeletal function. Autophagy, an intricate intracellular mechanism for degrading and recycling cellular components, plays a multifaceted role in bone metabolism. It involves sequestering cellular waste, damaged proteins, and organelles within autophagosomes, which are then degraded and recycled. Autophagy's impact on bone health varies depending on factors such as regulation, cell type, environmental cues, and physiological context. Despite being traditionally considered a cytoplasmic process, autophagy is subject to transcriptional and epigenetic regulation within the nucleus. However, the precise influence of epigenetic regulation, including DNA methylation, histone modifications, and non-coding RNA expression, on cellular fate remains incompletely understood. The interplay between autophagy and epigenetic modifications adds complexity to bone cell regulation. This article provides an in-depth exploration of the intricate interplay between these two regulatory paradigms, with a focus on the epigenetic control of autophagy in bone metabolism. Such an understanding enhances our knowledge of bone metabolism-related disorders and offers insights for the development of targeted therapeutic strategies.