Search results for "Histone"

Epigenetic Mechanisms as Key Regulators in Disease

2016

Epigenetics is a rapidly growing field of research which studies the changes in the gene expression that do not involve changes in the nucleotide sequence. The cellular metabolism is directly connected to epigenetic regulation through the inflow of different metabolites such as S-adenosylmethionine, acetyl-CoA, and α-ketoglutarate among others, which serve as substrates or cofactors for chromatin-modifying enzymes. These metabolites define how our lifestyle (i.e., nutrition, physical activity, and other healthy behaviors) acts on gene expression by epigenetic mechanisms. Therefore, proper coordination between components of the epigenetic machineries is essential for the correct control of t…

Histone-mediated transgenerational epigenetics

2019

Abstract Epigenetic mechanisms operate at the interface between the environment and genome, by converting the environmental stimuli to phenotypic responses through changes in the chromatin landscape, which ultimately affects gene expression in the absence of alterations in DNA sequence. In this scenario, transgenerational inheritance occurs when epigenetic variations induced by environmental stimuli are transmitted through the germ line to succeeding generations that had never experienced those stimuli. There is an ever-growing list of reports indicating that histones are fundamental players in these processes in a variety of organisms. In this chapter, we provide a perspective on histone-d…

Deciphering the histone code to build the genome structure

2017

Histones are punctuated with small chemical modifications that alter their interaction with DNA. One attractive hypothesis stipulates that certain combinations of these histone modifications may function, alone or together, as a part of a predictive histone code to provide ground rules for chromatin folding. We consider four features that relate histone modifications to chromatin folding: charge neutralisation, molecular specificity, robustness and evolvability. Next, we present evidence for the association among different histone modifications at various levels of chromatin organisation and show how these relationships relate to function such as transcription, replication and cell division…

Linker histone H1 is essential for Drosophila development, the establishment of pericentric heterochromatin, and a normal polytene chromosome structu…

2009

We generated mutant alleles of Drosophila melanogaster in which expression of the linker histone H1 can be down-regulated over a wide range by RNAi. When the H1 protein level is reduced to ∼20% of the level in wild-type larvae, lethality occurs in the late larval – pupal stages of development. Here we show that H1 has an important function in gene regulation within or near heterochromatin. It is a strong dominant suppressor of position effect variegation (PEV). Similar to other suppressors of PEV, H1 is simultaneously involved in both the repression of euchromatic genes brought to the vicinity of pericentric heterochromatin and the activation of heterochromatic genes that depend on their pe…

Abstract 4479: Unveiling the relationship between the SWI/SNF chromatin remodeling complex and noncoding RNAs

2016

Abstract Chromatin remodeling complexes are crucial for the viability of the cells due to their role in regulating interactions between DNA and histones and, therefore, modifying the accessibility of the genetic information to the transcriptional machinery. This relevance can also been seen in the SWI/SNF complex that has been associated with cancer in the last deep-sequencing efforts on tumoral genomes. BRG1 is the helicase/ATPase catalytic subunit of the SWI/SNF complex and it is frequently lost in NSCLC cell lines with a high mutation rate. In primary tumors, the loss of expression of BRG1 is also frequent, however it cannot be explained by mutations or by promoter hypermethylation. In t…

Histone acetylation regulates the expression of genes involved in worker reproduction and lifespan in the ant Temnothorax rugatulus

2021

In insect societies, the queen monopolizes reproduction while workers perform tasks such as brood care or foraging. Queen loss leads to ovary development and lifespan extension in workers from many ants. However, the underlying molecular mechanisms of this phenotypic plasticity remain unclear. Recent studies highlight the importance of epigenetics in regulating plastic traits in social insects. We investigated the role of histone acetylation in the regulation of worker reproduction in the ant Temnothorax rugatulus. We removed queens from their colonies to induce worker fecundity, and either fed workers with chemical inhibitors of histone acetylation (C646), deacetylation (Trichostatin A), o…

Gene expression during early embryogenesis of sea urchin: The histone and homeobox genes

1997

Transcriptional regulators are thought to play a key role in cell fate determination and territorial specification in sea urchin. Our goals are to clone transcription factors for studying embryonic development. One approach has been to use promoter binding and gene transfer technology to investigate the mechanisms of transcriptional activation and repression of the early H2A histone gene. By this analysis we identified a transcriptional activator, the MBF-1, that binds to the modulator element of the H2A gene and enhances the activity of the H2A promoter. However, the enhancer activity of the modulator and its interaction with MBF-1 also occurs at the gastrula stage when the early histone g…

Genetic and Cytological Analysis of Drosophila Chromatin-Remodeling Factors

2003

Methyl-CpG-binding proteins

2000

CpG methylation, the most common epigenetic modification of vertebrate genomes, is primarily associated with transcriptional repression. MeCP2, MBD1, MBD2, MBD3 and MBD4 constitute a family of vertebrate proteins that share the methyl-CpG-binding domain (MBD). The MBD, consisting of about 70 residues, possesses a unique alpha/beta-sandwich structure with characteristic loops, and is able to bind single methylated CpG pairs as a monomer. All MBDs except MBD4, an endonuclease that forms a complex with the DNA mismatch-repair protein MLH1, form complexes with histone deacetylase. It has been established that MeCP2, MBD1 and MBD2 are involved in histone deacetylase-dependent repression and it i…

New Foldback transposable element TFB1 found in histone genes of the midge Chironomus thummi

1990

A new Foldback transposable element (TFB1) has been found in the histone H1-H3 intergenic region in the midge Chironomus thummi thummi. TFB1 has long terminal inverted repeats, composed of short, degenerate subrepeats and is flanked by nine or ten base-pair “target site” duplications. TFB1 is present in at least two adjacent histone gene units in Ch. th. thummi, indicating a homogenization of histone gene repeats. The copy number and chromosomal distribution of TFB1 are different in the closely related subspecies Ch. th. thummi and Ch. th. piger, showing that amplification, elimination and transposition of TFB1 have occurred recently during evolution.