Explore the vast range of titles available.

Enhancers are -regulatory elements in the genome that cooperate with promoters to control target gene transcription. Unlike promoters, enhancers are not necessarily adjacent to target genes and can exert their functions regardless of enhancer orientations, positions and spatial segregations from target genes. Thus, for a long time, the question as to how enhancers act in a temporal and spatial manner attracted considerable attention. The recent discovery that enhancers are also abundantly transcribed raises interesting questions about the exact roles of enhancer RNA (eRNA) in gene regulation. In this review, we highlight the process of enhancer transcription and the diverse features of eRNA. We review eRNA functions, which include enhancer-promoter looping, chromatin modifying, and transcription regulating. As eRNA are transcribed from active enhancers, they exhibit tissue and lineage specificity, and serve as markers of cell state and function. Finally, we discuss the unique relationship between eRNA and super enhancers in phase separation wherein eRNA may contribute significantly to cell fate decisions.

Epstein–Barr virus (EBV) super-enhancers (ESEs) are essential for lymphoblastoid cell (LCL) growth and survival. Reanalyses of LCL global run-on sequencing (Gro-seq) data found abundant enhancer RNAs (eRNAs) being transcribed at ESEs. Inactivation of ESE components, EBV nuclear antigen 2 (EBNA2) and bromodomain-containing protein 4 (BRD4), significantly decreased eRNAs at ESEs −428 and −525 kb upstream of the MYC oncogene transcription start site (TSS). shRNA knockdown of the MYC −428 and −525 ESE eRNA caused LCL growth arrest and reduced cell growth. Furthermore, MYC ESE eRNA knockdown also significantly reduced MYC expression, ESE H3K27ac signals, and MYC ESEs looping to MYC TSS. These data indicate that ESE eRNAs strongly affect cell gene expression and enable LCL growth.

The field of eDNA is growing exponentially in response to the need for detecting rare and invasive species for management and conservation decisions. Developing technologies and standard protocols within the biosecurity sector must address myriad challenges associated with marine environments, including salinity, temperature, advective and deposition processes, hydrochemistry and pH, and contaminating agents. These approaches must also provide a robust framework that meets the need for biosecurity management decisions regarding threats to human health, environmental resources, and economic interests, especially in areas with limited clean-laboratory resources and experienced personnel. This contribution aims to facilitate dialogue and innovation within this sector by reviewing current approaches for sample collection, post-sampling capture and concentration of eDNA, preservation, and extraction, all through a biosecurity monitoring lens.

Environmental RNA (eRNA) is gaining ground as an environmental monitoring tool. Whereas eDNA is mainly utilized for species detection, eRNA may provide additional classes of inference. The comparatively more rapid signal decay rates of eRNA provide narrower temporal windows for species presence, while detection of environmental messenger RNAs (e‐mRNAs) could provide evidence of genomic responses to environmental stressors. We explored e‐mRNA as an environmental tracer for stress imposed on animal populations by investigating the decay dynamics of e‐mRNA gene detections from target organism presence to recent presence. We tested seven select e‐mRNAs of known molecular targets of perfluorooctanesulfonic acid (PFOS) toxicity in tanks containing zebrafish (Danio rerio) exposed to an environmentally relevant concentration of PFOS. eRNA samples were collected just prior to fish removal following a 21‐day exposure and continued over nine timepoints across 3 days. The quantity and quality of total eRNA declined over time for both treatments, but were still detectable at 72 h post fish removal. The PFOS exposure failed to elicit observable shifts in e‐mRNA target concentrations compared to control tanks, perhaps because the selected gene targets are primarily responsive to PFOS in liver and kidney, which may not contribute strong eRNA signatures. Detection rates for all e‐mRNAs dropped significantly beyond 3 h post fish removal, with most being undetectable by 72 h. The signal lifespan of e‐mRNAs in this study implies that the detection of such traces will be a strong indicator of target organism presence (or recent presence), and that given the right combination of stressor concentrations, impacted tissues or organs, and gene targets, contaminant impacts on organism health should be detectable in environmental samples. Future studies targeting toxicologically effective stressor doses for well‐established gene targets will be an important advancement in establishing the utility of e‐mRNA as a noninvasive environmental stressor monitoring tool. We evaluated e‐mRNAs of known molecular targets of perfluorooctanesulfonic acid (PFOS) toxicity in zebrafish in a controlled laboratory experiment. The detection patterns of e‐mRNAs in our study imply that diminishing detection of these traces over time is a strong indicator of target organism presence (or very recent presence), providing a narrower timeframe of detection than eDNA provides. Our study also suggests that contaminant impacts on organism health should be detectable in water samples, given the right combination of stressor concentrations, impacted tissues or organs, and gene targets.

Recent developments in environmental DNA (eDNA) analysis allow more rapid and extensive biomonitoring than traditional capture‐based surveys do. However, detection of eDNA not derived from living organisms may lead to false‐positive inferences of species presence. Such limitations may be overcome by utilizing RNA molecules present in the environment (environmental RNA [eRNA]) because of their physiochemical instability. Nevertheless, the biomonitoring performance of eRNA analysis remains unclarified because of the substantial lack of knowledge regarding basic eRNA properties, such as its persistence and degradation mechanisms. Here, we performed a factorial aquarium experiment to assess the effects of water temperature (10, 20, and 30°C) and pH (4, 7, and 10) conditions on the degradation of zebrafish (Danio rerio) eDNA and eRNA, targeting the mitochondrial cytochrome b (CytB) and nuclear beta‐2‐microglobulin (b2m) genes. A linear mixed‐model analysis showed that the degradation of eRNA was significantly faster than that of eDNA. Higher water temperatures promoted both eDNA and eRNA degradation, and alkaline conditions substantially promoted eRNA but not eDNA degradation. This might be explained by the physicochemical characteristics of DNA and RNA molecules, the membranous structure surrounding them, and their susceptibility to environmental microbial activity. Moreover, the relative concentrations of zebrafish eRNA to eDNA decreased over time, inferring that the ratio of eRNA to eDNA concentrations can be used for estimating the elapsed time since the genomic material was released and the freshness of the target eDNA signal in the field. Nevertheless, given that the confidence intervals of the eDNA and eRNA decay rates tended to overlap for each treatment level, this study indicates that fish eRNA is not always degraded rapidly and is, in fact, more abundant in water than previously expected. This result favors the application of eRNA analysis to indicate living biotic assemblages. We compared the degradation of fish eDNA and eRNA under different temperature and pH conditions. Higher temperatures promoted both eDNA and eRNA degradation, and alkaline conditions substantially promoted eRNA, but not eDNA, degradation. The time‐series decrease of the relative concentrations of eRNA to eDNA may infer that the ratio of eRNA to eDNA yields can be an index of the freshness of the target eDNA signal in the field.

The precise spatiotemporal gene expression is orchestrated by enhancers that lack general sequence features and thus are difficult to be computationally identified. By nascent RNA sequencing combined with epigenome profiling, we detect active transcription of enhancers from the complex bread wheat genome. We find that genes associated with transcriptional enhancers are expressed at significantly higher levels, and enhancer RNA is more precise and robust in predicting enhancer activity compared to chromatin features. We demonstrate that sub-genome-biased enhancer transcription could drive sub-genome-biased gene expression. This study highlights enhancer transcription as a hallmark in regulating gene expression in wheat.

Enhancer RNAs (eRNAs), a class of non-coding RNAs (ncRNAs) transcribed from enhancer regions, serve as a type of critical regulatory element in gene expression. There is increasing evidence demonstrating that the aberrant expression of eRNAs can be broadly detected in various human diseases. Some studies also revealed the potential clinical utility of eRNAs in these diseases. In this review, we summarized the recent studies regarding the pathological mechanisms of eRNAs as well as their potential utility across human diseases, including cancers, neurodegenerative disorders, cardiovascular diseases and metabolic diseases. It could help us to understand how eRNAs are engaged in the processes of diseases and to obtain better insight of eRNAs in diagnosis, prognosis or therapy. The studies we reviewed here indicate the enormous therapeutic potency of eRNAs across human diseases.

The p53 transcription factor is a potent suppressor of tumor growth. We report here an analysis of its direct transcriptional program using Global Run-On sequencing (GRO-seq). Shortly after MDM2 inhibition by Nutlin-3, low levels of p53 rapidly activate ∼200 genes, most of them not previously established as direct targets. This immediate response involves all canonical p53 effector pathways, including apoptosis. Comparative global analysis of RNA synthesis vs steady state levels revealed that microarray profiling fails to identify low abundance transcripts directly activated by p53. Interestingly, p53 represses a subset of its activation targets before MDM2 inhibition. GRO-seq uncovered a plethora of gene-specific regulatory features affecting key survival and apoptotic genes within the p53 network. p53 regulates hundreds of enhancer-derived RNAs. Strikingly, direct p53 targets harbor pre-activated enhancers highly transcribed in p53 null cells. Altogether, these results enable the study of many uncharacterized p53 target genes and unexpected regulatory mechanisms. The growth, division and eventual death of the cells in the body are processes that are tightly controlled by hundreds of genes working together. If any of these genes are switched on (or off) in the wrong cell or at the wrong time, it can lead to cancer. It has been known for many years that the protein encoded by one gene in particular—called p53 —is nearly always switched off in cancer cells. The p53 protein normally acts like a ‘brake’ to slow the uncontrolled division of cells, and some researchers are working to find ways to switch on this protein in cancer cells. However, this approach appears to only work in specific cases of this disease. For better results, we need to understand how p53 is normally switched on, and what other genes this protein controls once it is activated. Allen et al. have now identified the genes that are directly switched on when cancer cells are treated with a drug that artificially activates the p53 protein. Nearly 200 genes were switched on, and almost three quarters of these genes had not previously been identified as direct targets of p53. Although p53 tends to act as a brake to slow cell division, it is not clear how it distinguishes between its target genes—some of which promote cell survival, while others promote cell death. Allen et al. found that survival genes are switched on more strongly than cell death genes via a range of different mechanisms; this may explain why most cancers can survive drug treatments that reactivate p53. Also, Allen et al. revealed that some p53 target genes are primed to be switched on, even before the p53 protein is activated, by proteins (and other molecules) acting in regions of the DNA outside of the genes. By uncovering many new gene targets for the p53 protein, the findings of Allen et al. could help researchers developing new drugs or treatments for cancer.

This contribution was supported by the BONUS Bio-C3 project (Art 185), funded jointly by the EU and the Research Council of Lithuania (Grant Agreement No. BONUS-1/2014) and the project BLUEPORTS from the Spanish Ministry of Economy and Competitiveness (Grant CGL2016-79209-R).

Enhancers not only activate target promoters to stimulate messenger RNA (mRNA) synthesis, but they themselves also undergo transcription to produce enhancer RNAs (eRNAs), the significance of which is not well understood. Transcription at the participating enhancer–promoter pair appears coordinated, but it is unclear why and how. Here, we employ cell-free transcription assays using constructs derived from the human GREB1 locus to demonstrate that transcription at an enhancer and its target promoter is interdependent. This interdependence is observable under conditions where direct enhancer–promoter contact (EPC) takes place. We demonstrate that transcription activation at a participating enhancer–promoter pair is dependent on i) the mutual availability of the enhancer and promoter, ii) the state of transcription at both the enhancer and promoter, iii) local abundance of both eRNA and mRNA, and iv) direct EPC. Our results suggest transcriptional interdependence between the enhancer and the promoter as the basis of their transcriptional concurrence and coordination throughout the genome. We propose a model where transcriptional concurrence, coordination and interdependence are possible if the participating enhancer and promoter are entangled in the form of EPC, reside in a proteinaceous bubble, and utilize shared transcriptional resources and regulatory inputs.