Inducible mouse models illuminate parameters influencing epigenetic inheritance

Identification of genetic associations between acute myocardial infarction and non-small cell lung cancer

Introduction

A growing body of evidence suggests a potential connection between myocardial infarction (MI) and lung cancer (LC). However, the underlying pathogenesis and molecular mechanisms remain unclear. This research aims to identify common genes and pathways between MI and LC through bioinformatics analysis.

Methods

Two public datasets (GSE166780 and GSE8569) were analyzed to identify differentially expressed genes (DEGs). Common DEGs were enriched using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Hub genes were identified and their diagnostic performance was evaluated. Gene co-expression networks, as well as regulatory networks involving miRNA-hub genes and TF-hub genes, were also constructed. Finally, candidate drugs were predicted.

Results

Among the datasets, 34 common trend DEGs were identified. Enrichment analysis linked these DEGs to key biological processes, cellular components, and molecular functions. Eight hub genes (CEBPA, TGFBR2, EZH2, JUNB, JUN, FOS, PLAU, COL1A1) were identified, demonstrating promising diagnostic accuracy. Key transcription factors associated with these hub genes include SP1, ESR1, CREB1, ETS1, NFKB1, and RELA, while key miRNAs include hsa-mir-101-3p, hsa-mir-124-3p, hsa-mir-29c-3p, hsa-mir-93-5p, and hsa-mir-155-5p. Additionally, potential therapeutic drugs were identified, with zoledronic acid anhydrous showing potential value in reducing the co-occurrence of the two diseases.

Discussion

This study identified eight common signature genes shared between NSCLC and AMI. Validation datasets confirmed the diagnostic value of key hub genes COL1A1 and PLAU. These findings suggest that shared hub genes may serve as novel therapeutic targets for patients with both diseases. Ten candidate drugs were predicted, with zoledronic acid showing potential for targeting dual hub genes, offering a promising therapeutic approach for the comorbidity of lung cancer and myocardial infarction.

A Ubiquitous Chromatin Opening Element and DNA Demethylation Facilitate Doxycycline-Controlled Expression during Differentiation and in Transgenic Mice

Synthetic expression cassettes provide the ability to control transgene expression in experimental animal models through external triggers, enabling the study of gene function and the modulation of endogenous regulatory networks in vivo. The performance of synthetic expression cassettes in transgenic animals critically depends on the regulatory properties of the respective chromosomal integration sites, which are affected by the remodeling of the chromatin structure during development. The epigenetic status may affect the transcriptional activity of the synthetic cassettes and even lead to transcriptional silencing, depending on the chromosomal sites and the tissue. In this study, we investigated the influence of the ubiquitous chromosome opening element (UCOE) HNRPA2B1-CBX3 and its subfragments A2UCOE and CBX3 on doxycycline-controlled expression modules within the chromosomal Rosa26 locus. While HNRPA2B1-CBX3 and A2UCOE reduced the expression of the synthetic cassettes in mouse embryonic stem cells, CBX3 stabilized the expression and facilitated doxycycline-controlled expression after in vitro differentiation. In transgenic mice, the CBX3 element protected the cassettes from overt silencing although the expression was moderate and only partially controlled by doxycycline. We demonstrate that CBX3-flanked synthetic cassettes can be activated by decitabine-mediated blockade of DNA methylation or by specific recruitment of the catalytic demethylation domain of the ten-eleven translocation protein TET1 to the synthetic promoter. This suggests that CBX3 renders the synthetic cassettes permissive for subsequent epigenetic activation, thereby supporting doxycycline-controlled expression. Together, this study reveals a strategy for overcoming epigenetic constraints of synthetic expression cassettes, facilitating externally controlled transgene expression in mice.

Controlled re-activation of epigenetically silenced Tet promoter-driven transgene expression by targeted demethylation

Faithful expression of transgenes in cell cultures and mice is often challenged by locus dependent epigenetic silencing. We investigated silencing of Tet-controlled expression cassettes within the mouse ROSA26 locus. We observed pronounced DNA methylation of the Tet promoter concomitant with loss of expression in mES cells as well as in differentiated cells and transgenic animals. Strikingly, the ROSA26 promoter remains active and methylation free indicating that this silencing mechanism specifically affects the transgene, but does not spread to the host's chromosomal neighborhood. To reactivate Tet cassettes a synthetic fusion protein was constructed and expressed in silenced cells. This protein includes the enzymatic domains of ten eleven translocation methylcytosine dioxygenase 1 (TET-1) as well as the Tet repressor DNA binding domain. Expression of the synthetic fusion protein and Doxycycline treatment allowed targeted demethylation of the Tet promoter in the ROSA26 locus and in another genomic site, rescuing transgene expression in cells and transgenic mice. Thus, inducible, reversible and site-specific epigenetic modulation is a promising strategy for reactivation of silenced transgene expression, independent of the integration site.

What do you mean, "epigenetic"?

Interest in the field of epigenetics has increased rapidly over the last decade, with the term becoming more identifiable in biomedical research, scientific fields outside of the molecular sciences, such as ecology and physiology, and even mainstream culture. It has become increasingly clear, however, that different investigators ascribe different definitions to the term. Some employ epigenetics to explain changes in gene expression, others use it to refer to transgenerational effects and/or inherited expression states. This disagreement on a clear definition has made communication difficult, synthesis of epigenetic research across fields nearly impossible, and has in many ways biased methodologies and interpretations. This article discusses the history behind the multitude of definitions that have been employed since the conception of epigenetics, analyzes the components of these definitions, and offers solutions for clarifying the field and mitigating the problems that have arisen due to these definitional ambiguities.