Epigenetic Research Articles

Genetically encoded epigenetic sensors for visualization of H3K9me3, H3K9ac and H3K4me1 histone modifications in living cells

Post-translational modifications of histones play a crucial role in chromatin structure maintenance and epigenetic regulation. The LiveMIEL (Live-cell Microscopic Imaging of Epigenetic Landscape) method represents a promising approach for tracking histone modifications. It involves visualization of epigenetic modifications using genetically encoded fluorescent sensors and further analysis of the obtained intranuclear patterns by multiparametric image analysis. In this study, we designed three new red fluorescent sensors—MPP8-Red, AF9-Red and DPF3-Red—for live-cell visualization of patterns of H3K9me3, H3K8ac and H3K4me1, respectively. The observed fluorescent patterns were visually distinguishable, and LiveMIEL analysis clearly classified them into three corresponding groups. We propose that these sensors can be used for live-cell dynamic analysis of changes in organization of three epigenetic types of chromatin.

Whole genome regulatory effect of MoISW2 and consequences for the evolution of the rice plant pathogenic fungus Magnaporthe oryzae.

Isw2 proteins, ubiquitous across eukaryotes, exhibit a propensity for DNA binding and exert dynamic influences on local chromosome condensation in an ATP-dependent fashion, thereby modulating the accessibility of neighboring genes to transcriptional machinery. Here, we report the deletion of a putative MoISW2 gene, yielding substantial ramifications on plant pathogenicity. Subsequent gene complementation and chromatin immunoprecipitation sequencing (ChIP-seq) analyses were conducted to delineate binding sites. RNA sequencing (RNA-seq) assays revealed discernible impacts on global gene regulation along chromosomes in both mutant and wild-type strains, with comparative analyses against 55 external RNA-seq data sets corroborating these findings. Notably, MoIsw2-mediated binding and activities delineate genomic loci characterized by pronounced gene expression variability proximal to MoIsw2 binding sites, juxtaposed with comparatively stable expression in surrounding regions. The contingent genes influenced by MoIsw2 activity predominantly encompass niche-determinant genes, including those encoding secreted proteins, secondary metabolites, and stress-responsive elements, alongside avirulence genes. Furthermore, our investigations unveil a spatial correlation between MoIsw2 binding motifs and known transposable elements (TEs), suggesting a potential interplay wherein TE transposition at these loci could modulate the transcriptional landscape of Magnaporthe oryzae in a strain-specific manner. Collectively, these findings position MoIsw2 as a plausible master regulator orchestrating the delicate equilibrium between genes vital for biomass proliferation, akin to housekeeping genes, and niche-specific determinants crucial for ecological adaptability. Stress-induced TE transposition, in conjunction with MoIsw2 activity, emerges as a putative mechanism fostering enhanced mutagenesis and accelerated evolution of niche-determinant genes relative to housekeeping counterparts.IMPORTANCEIsw2 proteins are conserved in plants, fungi, animals, and other eukaryotes. We show that a fungal Isw2 protein in the rice pathogen Magnaporthe oryzae binds to retrotransposon (RT) DNA motifs and affects the epigenetic gene expression landscape of the fungal genome. Mainly ecological niche determinant genes close to the binding motifs are affected. RT elements occur frequently in DNA between genes in most organisms. They move place and multiply in the genome, especially under physiological stress. We further discuss the Isw2 and RT combined activities as a possible sought-after mechanism that can cause biased mutation rates and faster evolution of genes necessary for reacting to abiotic and biotic challenges. The most important biotic challenges for plant pathogens are the ones from the host plants' innate immunity. The overall result of these combined activities will be an adaptation-directed evolution of niche-determinant genes.

Epigenetic Landscapes of Endometriosis: From Pathogenesis to Precision Medicine

Endometriosis, a challenging gynecological disorder characterized by the ectopic presence of endometrial-like tissue, presents significant diagnostic and therapeutic hurdles due to its complex etiology and diverse clinical manifestations. Recent advancements in understanding its pathogenesis have underscored the pivotal role of epigenetic alterations, offering new insights into disease mechanisms and therapeutic targets. Epigenetic changes in endometrial cells significantly contribute to endometriosis pathogenesis, disrupting normal physiology and hormone responsiveness, particularly to progesterone. Dysregulation of histone modifications, DNA methylation, and non-coding RNA expression disrupts cellular homeostasis and promotes disease progression. Histone modifications, notably methylation and acetylation, influence chromatin structure and gene expression, affecting progesterone responsiveness and disease progression. Epigenetic regulators such as Cfp1 modulate progesterone receptor expression and downstream signalling pathways, presenting potential therapeutic targets. Non-coding RNAs, including miRNAs and lncRNAs, exert regulatory effects on gene expression and are implicated in endometriosis pathogenesis. Dysregulated expression disrupts cellular homeostasis and promotes disease progression. Biomarker studies have identified specific miRNAs and lncRNAs associated with endometriosis, offering avenues for non-invasive diagnosis and targeted therapies. siRNA-based therapies targeting key genes involved in endometriosis pathogenesis show promise as novel treatment modalities. By modulating gene expression and cellular functions, siRNA-based therapies offer a targeted approach to mitigate pathological processes. In this review, we summarize recent findings in the molecular mechanisms and regulatory pathways of endometriosis, offering valuable insights into pathology and therapeutic interventions. Future research efforts aimed at elucidating the complex interplay between epigenetic regulators and disease pathways hold promise for innovative diagnostic tools and targeted therapies.

PRDM3/16 regulate chromatin accessibility required for NKX2-1 mediated alveolar epithelial differentiation and function

While the critical role of NKX2-1 and its transcriptional targets in lung morphogenesis and pulmonary epithelial cell differentiation is increasingly known, mechanisms by which chromatin accessibility alters the epigenetic landscape and how NKX2-1 interacts with other co-activators required for alveolar epithelial cell differentiation and function are not well understood. Combined deletion of the histone methyl transferases Prdm3 and Prdm16 in early lung endoderm causes perinatal lethality due to respiratory failure from loss of AT2 cells and the accumulation of partially differentiated AT1 cells. Combination of single-cell RNA-seq, bulk ATAC-seq, and CUT&RUN data demonstrate that PRDM3 and PRDM16 regulate chromatin accessibility at NKX2-1 transcriptional targets critical for perinatal AT2 cell differentiation and surfactant homeostasis. Lineage specific deletion of PRDM3/16 in AT2 cells leads to lineage infidelity, with PRDM3/16 null cells acquiring partial AT1 fate. Together, these data demonstrate that NKX2-1-dependent regulation of alveolar epithelial cell differentiation is mediated by epigenomic modulation via PRDM3/16.

Abstract B088: Epigenetic reprograming in ATM-deficient pancreatic cancer: targeting EZH2- mediated oncogenic traits

Abstract Despite extensive research, the complex biology of pancreatic ductal adenocarcinoma (PDAC) continues to impede progress in improving its prognosis. Its resistance to conventional therapies, along with diverse mutations, necessitate improved molecular stratification to develop tailored approaches and to improve survival of PDAC patients. Our previous studies on ATM- deficient models revealed that serine/threonine kinase ATM loss induces homologous recombination deficiency (HRD), promoting invasiveness and desmoplastic reactions, while also sensitizing tumors to platinum-based therapies and PARP1 inhibition. Interestingly, our data also identified the histone-methyltransferase EZH2 as a direct ATM substrate to operate as a crucial regulator of ATM-specific oncogenic traits. In detail, murine and human ATM-deficient tumors accumulated EZH2, suggesting that ATM status contributes to rewiring the epigenetic landscape of pancreatic tumors, subsequently supporting oncogenic features. To investigate how EZH2 impacts ATM-deficient PDAC pathogenesis, we generated conditional double ATM and EZH2-knockout in the Kras G12D/+ ; Ptf1a Cre/+ mice (AKC, Atm fl/fl ; LSL-Kras G12D/+ ; Ptf1a Cre/+ , and EAKC, Ezh2 fl/fl ; Atm fl/fl ; LSL-Kras G12D/+ ; Ptf1a Cre/+ ). EZH2 depletion in AKC mice prolonged overall survival and reinstated a differentiated phenotype. Furthermore, PDAC patients with negative ATM and EZH2 expression from the TCGA-PAAD cohort (PanCancer Atlas) also showed significantly extended progression-free survival compared to ATM neg EZH2 pos patients. In line, CRISPR/Cas9-mediated EZH2 depletion in ATM-deficient pancreatic cancer cells affected their epigenetic landscape and significantly upregulated transcriptomic programs associated with cell differentiation, thereby restoring differentiated tumor features ex vivo. We showed that ATM status significantly impacts EZH2 activity through a post-translational pathway, promoting tumor supportive EZH2 activity in pancreatic cancer. ATM kinase facilitates EZH2 ubiquitination and degradation by recruiting the Cullin1 E3-ubiquitin ligase complex. Additionally, combining an EZH2 inhibitor with PARP inhibition enhances cytotoxicity in ATM- deficient HRD PDAC. Overall, our findings demonstrate that ATM deficiency drives a pro- oncogenic mesenchymal differentiation program via the histone-methyltransferase EZH2. We emphasize the importance of stratifying patients based on ATM status before considering pharmacological interference with EZH2, offering a promising approach for targeting ATM- deficient HRD tumors. Citation Format: Elodie Roger, Anna Härle, Lukas Perkhofer, Elisabeth Hessmann, Alexander Kleger, Johann Gout. Epigenetic reprograming in ATM-deficient pancreatic cancer: targeting EZH2- mediated oncogenic traits [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B088.

Abstract B082: Oncogenic KRAS-mediated epigenetic reprogramming is altered by loss of Activating Transcription Factor 3

Abstract Introduction: Over 90% of PDAC patients harbor an activating KRAS mutation, the most common form being KRASG12D. However, additional genetic mutations and environmental events, including chronic or hereditary pancreatitis, are needed for KRAS mutations to lead to PDAC. Our laboratory showed Activating Transcription Factor 3 (ATF3) was required for repressing genes that stabilize the mature acinar cell phenotype and for KRASG12D-driven progression to advanced PanIN lesions. However, ATF3 contributes to gene activation and repression and has been linked to numerous transcription factors and epigenetic mediators, and how ATF3 affects PDAC progression remains unknown. We hypothesize that KRASG12D promotes ATF3-driven histone acetylation in precursor PanINs lesions. Methods: C57Bl/6l mice allowing for acinar-inducible KRASG12D combined with (Ptf1acreERTKRASG12D) or without (Ptf1acreERTKRASG12DAtf3-/-; APK) Atf3 deletion were treated with tamoxifen to induce KRASG12D. After 10 days, mice were treated with cerulein to induce injury and PanIN progression. Mice were sacrificed after two weeks and 3D organoid lines developed. RNA-seq and chromatin immunoprecipitation for H3K27 acetylation (H3K27ac) followed by sequencing (ChIP-seq) was performed. Bioinformatic analysis was used to identify differentially enriched pathways. Levels of acetyl-CoA, the substrate for acetylation, was compared between lines along with levels of H3K27ac, H3K4me1, H3K4me3, and H3K9me3 through western blots. Results and Discussion: KRASG12D expression promoted epigenetic reprogramming in PanINs, including dysregulation of H3K27ac enrichment. ChIP-seq results showed the absence of ATF3 reduces H3K27 acetylation preferentially at gene promoters and pathway analysis showed differential enrichment and activation of KRAS signaling. Mechanistically, ATF3-deleted mice have lower acetyl-CoA levels, linking ATF3 to metabolic pathways as a possible mechanism for gene regulation. Comparing genes with an ATF3-dependent acetylation pattern to a curated list of KRAS-targeted genes identified SMARCC2 (BAF170), a SWI/SNF complex subunit, and KDM1B, a histone demethylase affecting H3K4, suggesting a potential role for ATF3 in widespread epigenetic regulation. Public sequencing data from PDAC patients, supports these findings as ATF3 expression is positively correlated with expression of several SWI/SNF complex subunits and demethylases. Conclusion: This study highlights a role for ATF3- mediated epigenetic dysregulatio. In oncogenic KRAS-dependent PDAC. Targeting this ATF3- mediated epigenetic landscape could be a promising new therapeutic avenue. Citation Format: Fatemeh Mousavi, Christopher L Pin, Parisa Shooshtari. Oncogenic KRAS-mediated epigenetic reprogramming is altered by loss of Activating Transcription Factor 3 [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B082.

Abstract C077: Functional Dissection of the Highly Plastic Basal Cell State in Pancreatic Cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a treatment-refractory malignancy with a dismal prognosis. Targeting cancer cell plasticity—the capacity to adapt to cell-extrinsic pressure via non-genetic mechanisms—is a promising therapeutic strategy, yet cell states within PDAC harboring high plasticity remain poorly understood. Using genetically engineered mouse models driven by oncogenic KrasG12D and loss of p53 (“KPC” model), we profiled primary PDAC tumors using single-cell RNA sequencing and single cell ATAC sequencing. We identified a cancer cell differentiation state that co-expresses both epithelial and mesenchymal programs and has a distinct epigenetic landscape with accessible chromatin across gene sets that mark cancer cell states with divergent phenotypes, suggesting that this cell state is primed for cell state switching. Notably, this high-plasticity cell state (HPCS) signature aligns with a "basal" signature in human PDAC, which associates with poor prognosis and chemoresistance. To functionally interrogate the HPCS in PDAC progression, we developed a novel lineage-tracing and ablation system. Lineage-tracing experiments revealed that the HPCS has a robust capacity for differentiation into epithelial and mesenchymal states, indicating that the HPCS is functionally plastic and acts as a source of fixed malignant states. Strikingly, targeted elimination of the HPCS over short time periods resulted in tumor collapse, underscoring a critical role in tumor maintenance. Further, we found that the HPCS is highly dependent on KRAS activity, with acute KRAS inhibitor treatment leading to a selective depletion of the HPCS. Taken together, our data indicates that PDAC harbors a striking dependency on the HPCS and encourages therapeutic approaches aimed at eradicating this critical subset of cancer cells. Citation Format: Anupriya Singhal, Hannah C. Styers, Jonathan Rub, Zhuxuan Li, Zeynep Tarcan, Jill Hallin, Olca Basturk, Rona Yaeger, James G. Christensen, Doron Betel, Yan Yan, Elisa de Stanchina, Tuomas Tammela. Functional Dissection of the Highly Plastic Basal Cell State in Pancreatic Cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C077.

Glyphosate and a glyphosate-based herbicide dysregulate the epigenetic landscape of Homeobox A10 (Hoxa10) gene during the endometrial receptivity in Wistar rats.

We observed that gestational plus lactational exposure to glyphosate (Gly), as active ingredient, or a glyphosate-based herbicide (GBH) lead to preimplantation losses in F1 female Wistar rats. Here, we investigated whether GBH and/or Gly exposure could impair Hoxa10 gene transcription by inducing epigenetic changes during the receptive stage in rats, as a possible herbicide mechanism implicated in implantation failures. F0 dams were treated with Gly or a GBH through a food dose of 2mg Gly/kg bw/day from gestational day (GD) 9 up to lactational day 21. F1 female rats were bred, and uterine tissues were analyzed on GD5 (preimplantation period). Transcripts levels of Hoxa10, DNA methyltransferases (Dnmt1, Dnmt3a and Dnmt3b), histone deacetylases (Hdac-1 and Hdac-3) and histone methyltransferase (EZH2) were assessed by quantitative polymerase chain reaction (qPCR). Four CpG islands containing sites targeted by BstUI methylation-sensitive restriction enzyme and predicted transcription factors (TFs) were identified in Hoxa10 gene. qPCR-based methods were used to evaluate DNA methylation and histone post-translational modifications (hPTMs) in four regulatory regions (RRs) along the gene by performing methylation-sensitive restriction enzymes and chromatin immunoprecipitation assays, respectively. GBH and Gly downregulated Hoxa10 mRNA. GBH and Gly increased DNA methylation levels and Gly also induced higher levels than GBH in all the RRs analyzed. Both GBH and Gly enriched histone H3 and H4 acetylation in most of the RRs. While GBH caused higher H3 acetylation, Gly caused higher H4 acetylation in all RRs. Finally, GBH and Gly enhanced histone H3 lysine 27 trimethylation (H3K27me3) marker at 3 out of 4 RRs studied which was correlated with increased EZH2 levels. In conclusion, exposure to GBH and Gly during both gestational plus lactational phases induces epigenetic modifications in regulatory regions of uterine Hoxa10 gene. We show for the first time that Gly and a GBH cause comparable gene expression and epigenetic changes. Our results might contribute to delineate the mechanisms involved in the implantation failures previously reported. Finally, we propose that epigenetic information might be a valuable tool for risk assessment in the near future, although more research is needed to establish a cause-effect relationship.

Epigenetic regulation of cell state by H2AFY governs immunogenicity in high-risk neuroblastoma.

Childhood neuroblastoma with MYCN-amplification is classified as high-risk and often relapses after intensive treatments. Immune checkpoint blockade therapy against the PD-1/L1 axis shows limited efficacy in neuroblastoma patients and the cancer intrinsic immune regulatory network is poorly understood. Here, we leverage genome-wide CRISPR/Cas9 screens and identify H2AFY as a resistance gene to the clinically approved PD-1 blocking antibody, nivolumab. Analysis of single-cell RNA sequencing datasets reveals that H2AFY mRNA is enriched in adrenergic cancer cells and is associated with worse patient survival. Genetic deletion of H2afy in MYCN-driven neuroblastoma cells reverts in vivo resistance to PD-1 blockade by eliciting activation of the adaptive and innate immunity. Mapping of the epigenetic and translational landscape demonstrates that H2afy deletion promotes cell transition to a mesenchymal-like state. With a multi-omics approach, we uncover H2AFY-associated genes that are functionally relevant and prognostic in patients. Altogether, our study elucidates the role of H2AFY as an epigenetic gatekeeper for cell states and immunogenicity in high-risk neuroblastoma.

High Content Screening Assay of Inhibitors of the Legionella Pneumophila Histone Methyltransferase RomA in Infected Cells.

Resistance to anti-microbial agents is a world-wide health threat. Thus, there is an urgent need for new treatments. An alternative approach to disarm pathogens consists in developing drugs targeting epigenetic modifiers. Bacterial pathogens can manipulate epigenetic regulatory systems of the host to bypass defences to proliferate and survive. One example is Legionella pneumophila, a Gram-negative intracellular pathogen that targets host chromatin with a specific, secreted bacterial SET-domain methyltransferase named RomA. This histone methyltransferase specifically methylates H3 K14 during infection and is responsible for changing the host epigenetic landscape upon L. pneumophila infection. To inhibit RomA activity during infection, we developed a reliable high-content imaging screening assay, which we used to screen an in-house chemical library developed to inhibit DNA and histone methyltransferases. This assay was optimised using monocytic leukemic THP-1 cells differentiated into macrophages infected with L. pneumophila in a 96- or 384-well plate format using the Opera Phenix (Perkin Elmer) confocal microscope, combined with Columbus software for automated image acquisition and analysis. H3 K14 methylation was followed in infected, single cells and cytotoxicity was assessed in parallel. A first pilot screening of 477 compounds identified a potential starting point for inhibitors of H3 K14 methylation.

Unraveling the key role of chromatin structure in cancer development through epigenetic landscape characterization of oral cancer

Epigenetic alterations, such as those in chromatin structure and DNA methylation, have been extensively studied in a number of tumor types. But oral cancer, particularly oral adenocarcinoma, has received far less attention. Here, we combined laser-capture microdissection and muti-omics mini-bulk sequencing to systematically characterize the epigenetic landscape of oral cancer, including chromatin architecture, DNA methylation, H3K27me3 modification, and gene expression. In carcinogenesis, tumor cells exhibit reorganized chromatin spatial structures, including compromised compartment structures and altered gene-gene interaction networks. Notably, some structural alterations are observed in phenotypically non-malignant paracancerous but not in normal cells. We developed transformer models to identify the cancer propensity of individual genome loci, thereby determining the carcinogenic status of each sample. Insights into cancer epigenetic landscapes provide evidence that chromatin reorganization is an important hallmark of oral cancer progression, which is also linked with genomic alterations and DNA methylation reprogramming. In particular, regions of frequent copy number alternations in cancer cells are associated with strong spatial insulation in both cancer and normal samples. Aberrant methylation reprogramming in oral squamous cell carcinomas is closely related to chromatin structure and H3K27me3 signals, which are further influenced by intrinsic sequence properties. Our findings indicate that structural changes are both significant and conserved in two distinct types of oral cancer, closely linked to transcriptomic alterations and cancer development. Notably, the structural changes remain markedly evident in oral adenocarcinoma despite the considerably lower incidence of genomic copy number alterations and lesser extent of methylation alterations compared to squamous cell carcinoma. We expect that the comprehensive analysis of epigenetic reprogramming of different types and subtypes of primary oral tumors can provide additional guidance to the design of novel detection and therapy for oral cancer.

A comprehensive map of the aging blood methylome in humans

BackgroundDuring aging, the human methylome undergoes both differential and variable shifts, accompanied by increased entropy. The distinction between variably methylated positions (VMPs) and differentially methylated positions (DMPs), their contribution to epigenetic age, and the role of cell type heterogeneity remain unclear.ResultsWe conduct a comprehensive analysis of > 32,000 human blood methylomes from 56 datasets (age range = 6–101 years). We find a significant proportion of the blood methylome that is differentially methylated with age (48% DMPs; FDR < 0.005) and variably methylated with age (37% VMPs; FDR < 0.005), with considerable overlap between the two groups (59% of DMPs are VMPs). Bivalent and Polycomb regions become increasingly methylated and divergent between individuals, while quiescent regions lose methylation more uniformly. Both chronological and biological clocks, but not pace-of-aging clocks, show a strong enrichment for CpGs undergoing both mean and variance changes during aging. The accumulation of DMPs shifting towards a methylation fraction of 50% drives the increase in entropy, smoothening the epigenetic landscape. However, approximately a quarter of DMPs exhibit anti-entropic effects, opposing this direction of change. While changes in cell type composition minimally affect DMPs, VMPs and entropy measurements are moderately sensitive to such alterations.ConclusionThis study represents the largest investigation to date of genome-wide DNA methylation changes and aging in a single tissue, providing valuable insights into primary molecular changes relevant to chronological and biological aging.

Epigenetic Modifications and Diabetes: Unraveling the Interplay between Genetics, Lifestyle, and Disease Progression

Epigenetic modifications are increasingly recognized as critical factors in the pathogenesis and progression of diabetes, particularly type 2 diabetes mellitus (T2DM). This review examined the complex interplay between genetic predispositions, lifestyle factors, and epigenetic changes that contributed to the development of diabetes and its complications. Key epigenetic mechanisms, including DNA methylation, histone modifications, and non-coding RNAs, can alter gene expression without changing the underlying DNA sequence, thereby influencing metabolic pathways essential for insulin sensitivity and β-cell function. Environmental factors such as diet, physical activity, and exposure to toxins induced epigenetic alterations, linking lifestyle choices to diabetes risk. Moreover, these modifications had significant implications for the development of microvascular and macrovascular complications associated with diabetes, including retinopathy and cardiovascular disease. Understanding the epigenetic landscape of diabetes not only enhanced our comprehension of its underlying mechanisms but also opened new avenues for therapeutic interventions. This review synthesized findings from recent literature and highlights the potential for targeting epigenetic modifications in developing personalized treatment strategies. A comprehensive analysis of studies published over the last decade, focusing on the relationship between epigenetics and diabetes. Keywords: Epigenetics, Type 2 Diabetes Mellitus (T2DM), DNA Methylation, Lifestyle Factors, Diabetic Complications.

Inhibition of KDM2/7 Promotes Notochordal Differentiation of hiPSCs.

Intervertebral disc disease (IDD) is a debilitating spine condition that can be caused by intervertebral disc (IVD) damage which progresses towards IVD degeneration and dysfunction. Recently, human pluripotent stem cells (hPSCs) were recognized as a valuable resource for cell-based regenerative medicine in skeletal diseases. Therefore, adult somatic cells reprogrammed into human induced pluripotent stem cells (hiPSCs) represent an attractive cell source for the derivation of notochordal-like cells (NCs) as a first step towards the development of a regenerative therapy for IDD. Utilizing a differentiation method involving treatment with a four-factor cocktail targeting the BMP, FGF, retinoic acid, and Wnt signaling pathways, we differentiate CRISPR/Cas9-generated mCherry-reporter knock-in hiPSCs into notochordal-like cells. Comprehensive analysis of transcriptomic changes throughout the differentiation process identified regulation of histone methylation as a pivotal driver facilitating the differentiation of hiPSCs into notochordal-like cells. We further provide evidence that specific inhibition of histone demethylases KDM2A and KDM7A/B enhanced the lineage commitment of hiPSCs towards notochordal-like cells. Our results suggest that inhibition of KDMs could be leveraged to alter the epigenetic landscape of hiPSCs to control notochord-specific gene expression. Thus, our study highlights the importance of epigenetic regulators in stem cell-based regenerative approaches for the treatment of disc degeneration.

Epigenetic Regulation of DNA Methylation and RNA Interference in Gastric Cancer: A 2024 Update.

Gastric cancer (GC) remains a significant public health concern because of its lethality, underscoring the need for deeper insights into its molecular mechanisms. Recent studies have increasingly highlighted the role of epigenetic modifications as critical players in cancer progression. Despite their importance, research specifically addressing epigenetic factors in GC is relatively scarce. This paper seeks to bridge that gap by examining recent literature that elucidates the epigenetic landscape associated with GC. The investigation of long noncoding RNAs (lncRNAs) has revealed their substantial involvement in gene dysregulation and epigenetic alterations within GC tumors. Notably, lncRNAs such as LINC00853 and LINC01266 have been identified as significant contributors to the epigenetic modulation of gene expression. Furthermore, the overexpression of KAT5 and GPX4 has been shown to mitigate the antiproliferative effects resulting from the depletion of circRHOT1, suggesting a complex interplay between these molecules in GC pathophysiology. Another pivotal aspect of epigenetic regulation in GC involves modifications in N6-methyladenosine (m6A), which play crucial roles in mRNA maturation processes such as splicing, export, degradation, and translation. m6A modifications are known for their influence on various cancer-related pathways, thus presenting a potential avenue for targeted interventions. Our findings indicate that the most pronounced instances of epigenetic dysregulation in GC can be traced back to the effects of long lncRNAs and alterations in m6A modification patterns. This underscores the urgent need for comprehensive investigations into these epigenetic factors, as a deeper understanding could lead to enhanced diagnostic markers and innovative therapeutic strategies. The integration of genetic and epigenetic considerations is essential for advancing the field of GC research. This synthesis of recent findings concerning epigenetic regulation offers valuable insights that could inform future studies and therapeutic developments. There is a critical need for ongoing research to elucidate the complexities of epigenetic modifications in GC, ultimately improving patient outcomes through tailored interventions.

Tracking induced pluripotent stem cell differentiation with a fluorescent genetically encoded epigenetic probe

Epigenetic modifications (methylation, acetylation, etc.) of core histones play a key role in regulation of gene expression. Thus, the epigenome changes strongly during various biological processes such as cell differentiation and dedifferentiation. Classical methods of analysis of epigenetic modifications such as mass-spectrometry and chromatin immuno-precipitation, work with fixed cells only. Here we present a genetically encoded fluorescent probe, MPP8-Green, for detecting H3K9me3, a histone modification associated with inactive chromatin. This probe, based on the chromodomain of MPP8, allows for visualization of H3K9me3 epigenetic landscapes in single living cells. We used this probe to track changes in H3K9me3 landscapes during the differentiation of induced pluripotent stem cells (iPSCs) into induced neurons. Our findings revealed two major waves of global H3K9me3 reorganization during 4-day differentiation, namely on the first and third days, whereas nearly no changes occurred on the second and fourth days. The proposed method LiveMIEL (Live-cell Microscopic Imaging of Epigenetic Landscapes), which combines genetically encoded epigenetic probes and machine learning approaches, enables classification of multiparametric epigenetic signatures of single cells during stem cell differentiation and potentially in other biological models.

A Boolean model explains phenotypic plasticity changes underlying hepatic cancer stem cells emergence

In several carcinomas, including hepatocellular carcinoma, it has been demonstrated that cancer stem cells (CSCs) have enhanced invasiveness and therapy resistance compared to differentiated cancer cells. Mathematical-computational tools could be valuable for integrating experimental results and understanding the phenotypic plasticity mechanisms for CSCs emergence. Based on the literature review, we constructed a Boolean model that recovers eight stable states (attractors) corresponding to the gene expression profile of hepatocytes and mesenchymal cells in senescent, quiescent, proliferative, and stem-like states. The epigenetic landscape associated with the regulatory network was analyzed. We observed that the loss of p53, p16, RB, or the constitutive activation of β-catenin and YAP1 increases the robustness of the proliferative stem-like phenotypes. Additionally, we found that p53 inactivation facilitates the transition of proliferative hepatocytes into stem-like mesenchymal phenotype. Thus, phenotypic plasticity may be altered, and stem-like phenotypes related to CSCs may be easier to attain following the mutation acquisition.

Activating mutations remodel the chromatin accessibility landscape to drive distinct regulatory networks in KMT2A-rearranged acute leukemia.

Activating FLT3 and RAS mutations commonly occur in leukemia with KMT2A-gene rearrangements (KMT2A-r). However, how these mutations cooperate with the KMT2A-r to remodel the epigenetic landscape is unknown. Using a retroviral acute myeloid leukemia (AML) mouse model driven by KMT2A::MLLT3, we show that FLT3 ITD , FLT3 N676K , and NRAS G12D remodeled the chromatin accessibility landscape and associated transcriptional networks. Although the activating mutations shared a common core of chromatin changes, each mutation exhibits unique profiles with most opened peaks associating with enhancers in intronic or intergenic regions. Specifically, FLT3 N676K and NRAS G12D rewired similar chromatin and transcriptional networks, distinct from those mediated by FLT3 ITD . Motif analysis uncovered a role for the AP-1 family of transcription factors in KMT2A::MLLT3 leukemia with FLT3 N676K and NRAS G12D , whereas Runx1 and Stat5a/Stat5b were active in the presence of FLT3 ITD . Furthermore, transcriptional programs linked to immune cell regulation were activated in KMT2A-r AML expressing NRAS G12D or FLT3 N676K , and the expression of NKG2D-ligands on KMT2A-r cells rendered them sensitive to CAR T cell-mediated killing. Human KMT2A-r AML cells could be pharmacologically sensitized to NKG2D-CAR T cells by treatment with the histone deacetylase inhibitor LBH589 (panobinostat) which caused upregulation of NKG2D-ligand levels. Co-treatment with LBH589 and NKG2D-CAR T cells enabled robust AML cell killing, and the strongest effect was observed for cells expressing NRAS G12D . Finally, the results were validated and extended to acute leukemia in infancy. Combined, activating mutations induced mutation-specific changes in the epigenetic landscape, leading to changes in transcriptional programs orchestrated by specific transcription factor networks.

Pathomechanistic Networks of Motor System Injury in Amyotrophic Lateral Sclerosis.

Amyotrophic Lateral Sclerosis (ALS) is the most common, adult-onset, progressive motor neurodegenerative disorder that results in death within 3 years of the clinical diagnosis. Due to the clinicopathological heterogeneity, any reliable biomarkers for diagnosis or prognosis of ALS have not been identified till date. Moreover, the only three clinically approved treatments are not uniformly effective in slowing the disease progression. Over the last 15 years, there has been a rapid advancement in research on the complex pathomechanistic landscape of ALS that has opened up new avenues for successful clinical translation of targeted therapeutics. Multiple studies suggest that the age-dependent interaction of risk-associated genes with environmental factors and endogenous modifiers is critical to the multi-step process of ALS pathogenesis. In this review, we provide an updated discussion on the dysregulated cross-talk between intracellular homeostasis processes, the unique molecular networks across selectively vulnerable cell types, and the multisystemic nature of ALS pathomechanisms. Importantly, this work highlights the alteration in epigenetic and epitranscriptomic landscape due to gene-environment interactions, which have been largely overlooked in the context of ALS pathology. Finally, we suggest that precision medicine research in ALS will be largely benefitted from the stratification of patient groups based on the clinical phenotype, onset and progression, genome, exposome, and metabolic identities.

Heat shock transcription factor 1 facilitates liver cancer progression by driving super-enhancer-mediated transcription of MYCN.

Heat shock transcription factors (HSFs) play crucial roles in the development of malignancies. However, the specific roles of HSFs in hepatocellular carcinoma (HCC) have yet to be fully elucidated. To explore the involvement of the HSF family, particularly HSF1, in the progression and prognosis of HCC. We conducted a thorough analysis of HSF expression and copy number variations across various cancer datasets. Specifically focusing on HSF1, we examined its expression levels and prognostic implications in HCC. Invitro and invivo experiments were carried out to evaluate the impact of HSF1 on liver cancer cell proliferation. Additionally, we utilized CUT&Tag, H3K27 acetylation enrichment, and RNA sequencing (RNA-seq) to investigate the super-enhancer (SE) regulatory landscapes of HSF1 in liver cancer cell lines. HSF1 expression is elevated in HCC and is linked to poor prognosis in several datasets. HSF1 stimulates liver cancer cell proliferation both invitro and invivo, partly through modulation of H3K27ac levels, influencing enhancer distribution. Mechanistically, our findings demonstrate that HSF1 transcriptionally activates MYCN expression by binding to its promoter and SE elements, thereby promoting liver cancer cell proliferation. Moreover, increased MYCN expression was detected in HCC tumors and correlated with unfavorable patient outcomes. Our study sheds light on previously unexplored aspects of HSF1 biology, identifying it as a transcription factor capable of shaping the epigenetic landscape in the context of HCC. Given HSF1's potential as an epigenetic regulator, targeting the HSF1-MYCN axis could open up new therapeutic possibilities for HCC treatment. The HSF1-MYCN axis constitutes a transcription-dependent regulatory mechanism that may function as both a prognostic indicator and a promising therapeutic target in liver cancer. Further exploration of this axis could yield valuable insights into novel treatment strategies for HCC.