Euchromatin is typically found in gene rich regions of the genome that are accessible to factors involved in various biological processes including transcription, replication and recombination.
The acetyl group is widely believed to partially neutralize the positive electrostatic charge of the histone and reduce the ionic bonding between the histone and the negatively charged DNA, thereby making local DNA more accessible to transcription factor binding (Grunstein 1997; Zhang et al. 2003a; Liu et al. 2008; Sengupta and Seto 2004).
These studies suggest that increased turnover within a particular genomic region disrupts the local chromatin environment and renders genes accessible to transcription factors, subsequently leading to gene activation.
The silencing effect of PEV is generally attributed to a change in chromatin structure at the variegating locus that renders the gene less accessible to transcription factors [ 10].
These chemical changes alter the strength of the interaction between the DNA and the histones, making the DNA more or less accessible to transcription factors and changing the rate of transcription.
Y4 receptors are expressed in the arcuate nucleus of the hypothalamus (ARC) [27], [28], which is accessible to circulating factors such as PP [30].
This indicates that a decrease in modifications that make the chromatin more accessible to transcription factors and coactivators may be involved, but this is not the sole mechanism responsible for TLR2-mediated inhibition of transcriptional responses to IFN-γ.
These data suggest that the Gcm1 promoter may be less accessible to transacting factors in cultured TS cells, due to a condensed chromatin structure, thereby limiting induction by potential transcriptional regulators, such as PPARγ.
An important component of directing initiation events to the 5' end of genes is regulating chromatin in such a way that a more open configuration is situated at the 5' end, while DNA downstream of the promoter is less accessible to transcription factors [4], [5], [6].
Third, HDACi lead to increased acetylation of histones making chromatin more accessible to transcription factors.
