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In mammals, the post-meiotic phases of spermatogenesis direct a drastic compaction of the genome characterized by the replacement of the majority of histones by small basic non-histone proteins, transition proteins followed by protamines. Although the mechanisms controlling this process are poorly understood, available data suggest that the nucleosome, which represents the universal unit of genome organization in eukaryotes, is the target of specific events cooperating to globally transform DNA organization at a genomic scale. Indeed, after meiosis, nearly all nucleosomes associated with the male genome undergo successive modifications increasing their instability, finally leading to their dissociation and re-organization. The characterization of the underlying mechanisms is a real challenge and appears as essential for the understanding of male gametogenesis and associated pathologies., (© 2012 médecine/sciences – Inserm / SRMS.)

Evidence is to date accumulating to suggest that the nucleosome, the fundamental unit of chromatin and ubiquitous product of cell apoptosis, plays a key role in the pathogeny of systemic lupus erythematosus (SLE). Nucleosomes play a central role in the antinuclear antibody response in SLE. Lupus anti-dsDNA and antihistone antibodies are directed towards nucleosomes and belong together with nucleosome-specific antibodies to a broad anti-nucleosome antibody family. Besides anti-dsDNA, nucleosome-specific antibodies have a major role in the pathophysiology of SLE and emphazise the role of nucleosome-antinucleosome immune complexes. Antinucleosome IgG antibodies are a more sensitive marker of SLE than anti-dsDNA. High levels of antinucleosome IgG are almost exclusively found in SLE. Antinucleosome IgG3 are strongly correlated with the SLE disease activity index. Nucleosome can bind to the surface of several cell types and mediate the binding of antinucleosome antibodies. Understanding of the key role of the nucleosome has opened new therapeutic intervention in SLE, such a tolerance induction to the subnucleosomal particles.