Daphnia magna diapause-interrupted embryogenesis has changes in histone modifications at H3K9

The discovery of RNA interference has revealed complex roles for small RNAs in regulating gene expression and cellular physiology. Small RNAs have been demonstrated to be involved in post-transcriptional suppression of translation, targeted degradation of messenger RNAs, and transcriptional suppression via epigenetic modifications of histones and DNA. In fission yeast, RNAi mediates suppression of centromeric transcripts, whereas in plants, transcriptional gene silencing appears to be primarily an antiviral mechanism. In mammals, the well annotated functional role of RNAi is primarily post-transcriptional, but there is increasing evidence that this mechanism can also work to suppress or modulate gene transcription, although it is not clear what primary function this serves. We overview, compare, and contrast the transcriptional silencing pathways in yeast, plants, and mammals in this article. This minireview is intended to provide the reader with a framework of how the RNAi machinery appears to be universally involved in various aspects of transcriptional regulation with discussions of similarities and differences in the components and mechanisms of achieving transcriptional silencing.

Global Levels of Histone Modifications Predict Prognosis in Different Cancers

Chromatin Remodeling Is a Key Mechanism Underlying Cocaine-Induced Plasticity in Striatum

A Cellular Memory of Developmental History Generates Phenotypic Diversity in C. elegans

Promoter-targeted siRNAs Induce Gene Silencing of Simian Immunodeficiency Virus (SIV) Infection In Vitro

Silencing of the Meiotic Genes SMC1β and STAG3 in Somatic Cells by E2F6

Heterochromatin Protein 1γ Epigenetically Regulates Cell Differentiation and Exhibits Potential as a Therapeutic Target for Various Types of Cancers

Background: Emerging research implicates ethanol (EtOH)-induced epigenetic modifications in regulating gene expression and EtOH consumption. However, consensus on specific epigenetic modifications induced by EtOH has not yet emerged, making it challenging to identify mechanisms and develop targeted treatments. We hypothesized that chronic intermittent EtOH (CIE) induces persistent changes in histone modifications across the cerebral cortex (CCx), nucleus accumbens (NAc), and prefrontal cortex (PFC), and that these histone modifications are altered in a knock-in mouse strain with altered sensitivity to EtOH.Methods: C57BL/6J (B6) mice and α1SHLA knockin mice on a B6 background were exposed to 16 h of vapor EtOH or room air followed by 8 h of room air for 4 consecutive days and sacrificed at multiple time points up to 72 h following exposure. Histone modifications were assessed using Western blot and dot blot. RT-qPCR was used to study expression of chromatin modifying enzymes in NAc and PFC.Results: In NAc, CIE significantly increased acetylation of histone subunit H3 at lysine 9 (H3K9ac) but not lysine 14 (H3K14ac) or lysine 27 (H3K27ac). In PFC, CIE significantly increased H3K9ac but not H3K14 or H3K27ac. There were no significant changes at 8 or 72 h after EtOH exposure in either NAc or PFC. CIE was also associated with increased expression of Kat2b, Kat5, and Tet1 in NAc but not PFC. In CCx, CIE had a significant effect on levels of H3K18ac; there was also a significant effect of the α1SHLA mutation on levels of H3K27me3, H3K14ac, and H3K18ac as well as a trend for H3S10pK14ac.Conclusions: The EtOH-induced histone modifications observed were transient and varied significantly between brain regions. A genetic mutation that altered sensitivity to EtOH was associated with altered induction of histone modifications during CIE. These results have implications for studying EtOH-induced histone modifications and EtOH sensitivity.

Update on epigenetics in allergic disease

Regulation of transcription of the steroidogenic acute regulatory protein ( StAR) gene: temporal and spatial changes in transcription factor binding and histone modification

Epigenetics in Male Germ Cells

Small RNA-Mediated Epigenetic Myostatin Silencing

Estrogen-induced reactive oxygen species, through epigenetic reprogramming, causes increased growth in breast cancer cells

The multidrug-resistant phenotype of tumor cells is acquired via an increased capability of drug efflux by ABC transporters and causes serious problems in cancer treatment. With the aim to uncover whether changes induced by epigenetic mechanisms in the expression level of drug transporter genes correlates with changes in the drug resistance phenotypes of resistant cells, we studied the expression of drug transporters in rat hepatoma cell lines. We found that of the three major rat ABC transporter genes Abcb1a, Abcb1b and Abcc1 the activity of only Abcb1b increased significantly in colchicine-selected, drug-resistant cells. Increased transporter expression in drug-resistant cells results primarily from transcriptional activation. A change in histone modification at the regulatory regions of the chromosomally adjacent Abcb1a and Abcb1b genes differentially affects the levels of corresponding mRNAs. Transcriptional up- and down-regulation accompany an increase in acetylation levels of histone H3 lysine 9 at the promoter regions of Abcb1b and Abcb1a, respectively. Drug efflux activity, however, does not follow tightly the transcriptional activity of drug transporter genes in hepatoma cells. Our results point out the need for careful analysis of cause-and-effect relationships between changes in histone modification, drug transporter expression and drug resistance phenotypes.

Plants continuously adapt to their environments by responding to various intrinsic and extrinsic signals. They face numerous biotic and abiotic stresses such as extreme temperatures, drought, or pathogens, requiring complex regulatory mechanisms to control gene activity and adapt their proteome for survival. Epigenetic regulation plays a crucial role in these adaptations, potentially leading to both heritable and non-heritable changes across generations. This process enables plants to adjust their gene expression profiles and acclimate effectively. It is also vital for plant development and productivity, affecting growth, yield, and seed quality, and enabling plants to "remember" environmental stimuli and adapt accordingly. Key epigenetic mechanisms that play significant roles include DNA methylation, histone modification, and ubiquitin ligase complex activity. These processes, which have been extensively studied in the last two decades, have led to a better understanding of the underlying mechanisms and expanded the potential for improving agriculturally and economically important plant traits. DNA methylation is a fundamental process that regulates gene expression by altering chromatin structure. The addition of methyl groups to cytosines by DNA methylases leads to gene suppression, whereas DNA demethylases reverse this effect. Histone modifications, on the other hand, collectively referred to as the "histone code", influence chromatin structure and gene activity by promoting either gene transcription or gene silencing. These modifications are either recognized, added, or removed by a variety of enzymes that act practically as an environmental memory, having a significant impact on plant development and the responses of plants to environmental stimuli. Finally, ubiquitin ligase complexes, which tag specific histones or regulatory proteins with ubiquitin, are also crucial in plant epigenetic regulation. These complexes are involved in protein degradation and play important roles in regulating various cellular activities. The intricate interplay between DNA methylation, histone modifications, and ubiquitin ligases adds complexity to our understanding of epigenetic regulation. These mechanisms collectively control gene expression, generating a complex and branching network of interdependent regulatory pathways. A deeper understanding of this complex network that helps plants adapt to environmental changes and stressful conditions will provide valuable insights into the regulatory mechanisms involved. This knowledge could pave the way for new biotechnological approaches and plant breeding strategies aimed at enhancing crop resilience, productivity, and sustainable agriculture.