pericentromeralt

Pericentromeric, often written as pericentromeric region, describes the portion of a chromosome immediately surrounding the centromere. This region lies adjacent to the centromeric core and extends into surrounding chromatin to varying extents among species and chromosomes. In many organisms, pericentromeric DNA is rich in repetitive sequences and organized into heterochromatin, contributing to structural stability during cell division.

Composition and epigenetic features: The pericentromeric region contains abundant repetitive DNA, including satellite sequences and various transposable elements. It is typically enriched for heterochromatic histone marks such as H3K9me3 and is bound by heterochromatin protein 1 (HP1). DNA methylation is also common, reinforcing a transcriptionally repressed state. Although largely quiet, some transcription from pericentromeric repeats can occur and may participate in chromatin regulation.

Function: Pericentromeric heterochromatin supports chromosome stability and proper segregation by influencing chromatin architecture around the centromere and aiding cohesin-mediated sister chromatid cohesion near the kinetochore. This region helps suppress inappropriate recombination in repetitive DNA and contributes to the mechanical properties of chromosomes during mitosis and meiosis. Its organization also affects higher-order nuclear architecture.

Evolution and clinical relevance: Pericentromeric regions are among the most rapidly evolving parts of the genome due to repetitive DNA dynamics, leading to considerable interspecies and intraspecies variation. Instability or rearrangements in pericentromeric areas can be involved in chromosomal abnormalities, cancers, and reproductive disorders. Advances in long-read sequencing and chromatin mapping are improving understanding of these complex regions.