- Locus control region
Locus control regions (LCR) are defined by their ability to enhance the expression of linked genes to physiological levels in a tissue-specific and copy number-dependent manner at ectopic
chromatinsites. The concept that developmental and cell lineage-specific regulation of gene expression relies not only on gene-proximal elements such as promoters, enhancers, and silencers, but also on long-range interactions of various cis regulatory elements and dynamic chromatin alterations.
The LCR was identified over 20 years ago. In transgenic mouse studies it was determined that the LCR was required for normal regulation of beta-globin gene expression.Mark B. Gerstein "et al.", "What is a gene, post-ENCODE? History and updated definition," "Genome Research" 17(6) (2007): 669-681] Several models exist for how the LCR exerts its effects on transcription from a distance.
1. Looping model: LCR section of the DNA loops around to different extent over the desired gene of expression, so that the binding site of the transcriptional machinery (proteins) is in physical close proximity to bridge and affect the transcription of that specific gene.
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