Histone Gene Expression in the Human Testis

Abstract

The function of histones has been classically assigned to the formation of DNA-protein-complexes, called nucleosomes. A nucleosomal core consists of a stretch of DNA wrapped around an octamer of core histones (H2A, H2B, H3 and H4). A further condensation into higher order chromatin is achieved by the linker histone H1, which is associated with the nucleosome. Additionally, recent evidence suggest an active participation of histones in the transcription and regulation of genes (Wolfe, 1995). Several histone subtypes have been isolated which can be divided into replication-dependent, replication-independent (replacement) and tissue-specific isoforms. The expression of these subtypes varies with respect to the cell line and tissue investigated (Meergans et al., 1996). During spermatogenesis, the histone fraction of spermatogenic cells is largely replaced by testis specific isoforms in rat and mice (Doenecke and Drabent, 1995).