chromatin looping

Definition

Target type: biologicalprocess

A chromatin organization process that starts with the loading of an extrusion motor (by an SMC family complex) onto the chromatin, followed by chromatin extrusion that stops at loop anchoring sites on the chromosome. [PMID:32213323]

Chromatin looping is a fundamental process in eukaryotic cells that plays a crucial role in regulating gene expression. It involves the physical interaction of distant DNA segments, bringing them into close proximity within the nucleus. This process is mediated by specialized proteins known as chromatin remodelers and loop extrusion factors.

Chromatin remodelers are multi-protein complexes that utilize ATP hydrolysis to alter the structure of chromatin. They can slide nucleosomes along the DNA, reposition them, or even remove them entirely. These actions contribute to the accessibility of DNA to other regulatory proteins, including transcription factors and loop extrusion factors.

Loop extrusion factors, such as cohesin, are ring-shaped complexes that actively extrude DNA loops. They bind to DNA and then move along the DNA strand in a bidirectional manner, pulling the DNA through the ring. As the loop grows, the cohesin complex encounters other DNA segments, leading to the formation of DNA loops.

The formation of chromatin loops can bring together regulatory elements, such as enhancers and promoters, that are physically distant on the linear DNA sequence. This spatial proximity facilitates the interaction of transcription factors with their target genes, leading to changes in gene expression.

Chromatin looping is highly dynamic and can be regulated by various cellular signals. For example, changes in the expression levels of chromatin remodelers and loop extrusion factors, as well as the availability of ATP, can influence loop formation and stability. Additionally, post-translational modifications, such as phosphorylation and acetylation, can alter the activity of these proteins.

The formation of specific chromatin loops is essential for proper gene regulation and is involved in a wide range of cellular processes, including development, differentiation, and response to environmental stimuli. Disruptions in chromatin looping can contribute to various diseases, including cancer and developmental disorders.'
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Proteins (1)

Compounds (11)