Does heterochromatin increase gene expression?
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| Thus, in contrast to its repressive effect on transcription, heterochromatin does not influence ORI activity. | |
590 Citations | Heterochromatin has thus emerged as a key factor in epigenetic regulation of gene expression, chromosome behaviour and evolution. |
| Our analyses uncover unexpected regulatory roles for mRNA-processing factors that assemble dynamic heterochromatin to modulate gene expression. | |
| Recent findings indicate that heterochromatin serves as a molecular sink for factors involved in chromatin-mediated repression of gene expression; long-range interactions that position a euchromatic gene near a heterochromatin domain influence its susceptibility to transcriptional silencing. | |
20 Citations | Our results to date suggest that the three most proximal genes in 3L heterochromatin have key roles in development, and indicate strong effects of combinations of genetic modifiers of PEV on het gene expression. |
97 Citations | Inverted transposons within an array or increased proximity of an array to blocks of naturally occurring heterochromatin may increase transgene silencing without increasing HP1 labeling. |
179 Citations | These results suggest how heterochromatin proteins might be recruited to specific sites on DNA with resultant specific effects on gene expression. |
13 Citations | Our study indicates that the local chromatin structure creates a heterochromatin repressive environment to repress nearby gene expression. |
28 Citations | Gene expression can be affected by the proximity to the heterochromatin, by local histone modifications, and by the three-dimensional position within the nucleus. |
134 Citations | Our results indicate that components or modifiers of heterochromatin may have a chromosomal-context-dependent role in gene silencing and activation decisions in mammals. |
Related Questions
How does chromatin organization affect gene expression?5 answersChromatin organization plays a pivotal role in gene expression by structuring the DNA within the nucleus to either facilitate or impede access to genetic information. The compaction of DNA into chromatin is a dynamic process that influences essential nuclear processes such as transcription, replication, and repair, thereby affecting gene expression by modulating the accessibility of genes to the transcriptional machinery. The physical state of chromatin, whether as open euchromatin or closed heterochromatin, determines the accessibility of genes to transcription factors and RNA polymerases, with euchromatin being associated with active gene expression and heterochromatin with gene repression.
Nucleosome positioning around transcription start sites (TSSs) is crucial for coordinated gene activation, as chromatin remodeling factors regulate the exposure of genomic DNA to transcription factors by remodeling or removing nucleosomes. Furthermore, the three-dimensional (3D) organization of the genome into structures such as topologically associating domains (TADs) and chromosomal territories orchestrates the spatial arrangement of genes, enhancers, and promoters, facilitating or restricting their interactions in a manner that impacts gene expression.
Chromatin loops and the positioning of genes within the nuclear architecture, such as in transcription factories, are essential for the regulation of gene expression, suggesting that the transcriptional status of a gene is influenced by its spatial position within the nucleus. Additionally, genetic variability can perturb gene regulation by affecting the activity of regulatory elements and the 3D chromatin organization, thereby influencing gene expression and coexpression in a cell type-specific manner.
Disruptions in chromatin organization are linked to neurocognitive syndromes, underscoring the importance of chromatin structure in the regulation of genes critical for synaptic development and plasticity. Moreover, the dynamic nature of chromatin organization is highlighted by its role in facilitating state transitions in cells, where global changes in gene expression are associated with structural reorganizations of chromatin. This intricate interplay between chromatin organization and gene expression underscores the complexity of genomic regulation and the importance of chromatin dynamics in cellular function and identity.
How does histone modification affect gene expression regulation in eukaryotic cells?5 answersHistone modifications play a crucial role in regulating gene expression in eukaryotic cells. These modifications, such as acetylation, methylation, sumoylation, and deacetylation, impact the accessibility of DNA by altering the structure of chromatin. For instance, acetylation of histones leads to transcriptional activation, while deacetylation results in gene silencing. Additionally, histone modifications like H3K9ac, H3K4me3, and H3K27me3 exhibit specific genomic distributions that influence gene expression patterns and help maintain cellular identity through multiple cell divisions. Sumoylation of histones has been shown to suppress spurious transcription by coordinating with other modifications like ubiquitylation and methylation, highlighting the intricate crosstalk involved in maintaining transcriptional fidelity. These findings underscore the significance of histone modifications in the precise regulation of gene expression in eukaryotic cells.
Does a change in higher order of chromatin structure result in heterochrmatin and euchromatin?4 answersA change in higher-order chromatin structure indeed results in the distinction between heterochromatin and euchromatin. The transition from compacted heterochromatin to dispersed euchromatin involves a stepwise process, with chromatin hierarchical branching at four levels, indicating this transition. Enhancers, located in noncoding regions, regulate cell type-specific gene expression through enhancer-promoter interactions influenced by changes in higher-order chromatin structures between different cell types. Studies have shown that heterochromatin, characterized by high compaction, inhibits DNA transactions, while euchromatin allows for gene expression and other DNA processes. The structural and functional differences between these chromatin domains are crucial for genomic function and regulation in various biological processes.
What role does IFD-1 play in the regulation of heterochromatin in C. elegans?5 answersIFD-1, a protein in C. elegans, plays a crucial role in the regulation of heterochromatin. Studies have shown that IFD-1 interacts with a diverse set of heterochromatin proteins like HPL-2/HP1, LIN-13, LIN-61, LET-418/Mi-2, and H3K9me2 histone methyltransferase MET-2/SETDB1 to silence repetitive elements and prevent genotoxic stress in the germ line. Additionally, the distribution of H3K9me2, a modification associated with heterochromatin, is regulated by factors like CSR-1, EKL-1, and DRH-3, which participate in a regulatory network involving IFD-1 to promote diverse aspects of development. These findings highlight the intricate network of proteins, including IFD-1, involved in maintaining genome integrity through the regulation of heterochromatin in C. elegans.
Where do facultative heterochromatins localized in nucleus?5 answersFacultative heterochromatin is typically found in distinct spatial locations within the nucleus. Research suggests that facultative heterochromatin can be localized towards the nuclear periphery, along with other heterochromatic regions, such as constitutive heterochromatin. However, the positioning of genes in relation to heterochromatin compartments, including facultative heterochromatin, does not necessarily correlate with gene silencing. Studies have shown an unexpected inverse correlation between gene activity and the position relative to facultative heterochromatin at the nuclear periphery. This indicates that while facultative heterochromatin may be present towards the nuclear periphery, its specific role in gene regulation and genome organization is complex and not solely linked to gene silencing.
Do HSCs tend to be more heterochromatin vs. euchromatin?4 answersHematopoietic stem cells (HSCs) tend to have a differential packaging of their genomes into domains of euchromatin and heterochromatin. Euchromatin refers to the more open and transcriptionally active regions, while heterochromatin represents the more compact and transcriptionally repressive regions. The balance between euchromatin and heterochromatin is crucial for maintaining cell identity and gene regulation. While the specific distribution of heterochromatin and euchromatin in HSCs is not explicitly mentioned in the abstracts provided, it can be inferred that HSCs likely have a combination of both euchromatic and heterochromatic regions, as these different chromatin states play important roles in cell fate determination and gene expression regulation.