Human Nucleosome protein

Supplementary information

This supplementary information is collated from multiple sources and compiled automatically.

Nucleosome is a fundamental unit of chromatin consisting of DNA wrapped around histone proteins. Alternate names include chromatin fibers and DNA-histone complexes. Each nucleosome contains an octamer of histones (two copies each of H2A H2B H3 and H4) with DNA coiled around it measuring about 11 nm in diameter. Nucleosomes are expressed in the nucleus of eukaryotic cells forming the basic structure of chromatin which further compacts to fit within the nucleus.

Biological function summary

Nucleosomes organize and protect the DNA strand modulating access for DNA replication and transcription machinery. Nucleosomes are part of the larger chromatin complex and regulate gene expression by controlling DNA accessibility. Changes in histone modifications within nucleosomes alter chromatin's structure influencing the transcriptional activity of genes. This dynamic alteration is essential for cellular functions such as DNA repair replication and genome stability.

Pathways

Nucleosomes play central roles in the regulation of epigenetic pathways involved in gene expression and silencing. They interact with other proteins like histone-modifying enzymes and chromatin remodelers such as the Polycomb group proteins and the SWI/SNF complexes. These interactions impact pathways like the cell cycle control and DNA damage response coordinating cellular processes to maintain genomic integrity and respond to environmental signals.

Nucleosomes have significant links to cancer and autoimmune diseases. Alterations in nucleosome positioning or histone modifications can lead to aberrant gene expression contributing to oncogenesis. In cancers changes in histone modifications can activate oncogenes or silence tumor suppressor genes. Nucleosomes are also implicated in autoimmune disorders such as systemic lupus erythematosus where the immune system may produce antibodies against nucleosome components. Histones or nucleosomes released during cell death can exacerbate the autoimmune response.