Histones

Basic chromosomal protein molecules around which the DNA is wrapped in the cell nucleus. This packs the DNA tightly (DNA packaging). Nucleosomes are formed, which are strung together like pearls on a necklace.

Topoisomerase is an important enzyme that determines the packaging properties of histones. Numerous studies show that the acetylation of histones correlates with transcriptional activation and the deacetylation of histones with transcriptional repression. The opposing activities of two enzyme classes, histone acetyltransferases (HAT) and histone deacetylases (HDAC), control the extent of histone acetylation. Histone methylation and acetylation are characteristics of epigenetic changes.

Today, a number of drugs are available, so-called HDAC inhibitors, which make it possible to intervene in the histone code and influence epigenetic gene regulation. Although these substances modulate the expression of 2-5% of all genes, they are surprisingly not associated with significant side effects in vivo and are already being used therapeutically in cutaneous T-cell lymphomas (see Vorinostat below).

Anti-histone antibodies can be detected in about 30% of patients with systemic lupus erythematosus. Almost all patients with drug-induced lupus erythematosus have anti-histone antibodies.