A-K Faure | PubMed Health

PubMed2006

[Epigenetics of the sperm cell].

In addition to genetic information, the spermatozoon carries another type of information, named epigenetic, which is not associated with variations of the DNA sequence. In somatic cells, it is now generally admitted that epigenetic information is not only regulated by DNA methylation but also involves modifications of the genome structure, or epigenome. During male germ cell maturation, the epigenome is globally re-organized, since most histones, which are associated to DNA in somatic cells, are removed and replaced by sperm specific nuclear proteins, the protamines, responsible for the tight compaction of the sperm DNA. However, a small proportion of histones, and probably other proteins, are retained within the sperm nucleus, and the structure of the sperm genome is actually heterogeneous. This heterogeneity of the sperm epigenome could support an epigenetic information, transmitted to the embryo, which could be crucial for its development. Although it is nowadays possible to appreciate the global structure of the sperm genome, the precise constitution of the sperm epigenome remains unknown. In particular, very recent data suggest that specific regions of the genome could be associated with particular proteins and define specific structures. This structural partitioning of the sperm genome could convey important epigenetic information, crucial for the embryo development.

DNA↗

PubMed2004

[Organizing the sperm nucleus].

Thanks to the success of new assisted reproductive technology, including sperm microinjection (i.c.s.i.), men with severe spermatogenesis impairments can now become biological fathers. Whether the germinal cell used for i.c.s.i. is conveying appropriate genetic and epigenetic information is an important concern. However, to date, there is a huge lack of data on which information is epigenetically conveyed to the offspring and how. The basic support for epigenetic marks is the nucleus structure. During spermatogenesis, a major re-organization of the male germ cells nucleus structure occurs, which includes a global condensation associated with a removal of most core somatic histones and their replacement by sperm-specific nuclear proteins. The available data on the molecular mechanisms involved in this process and how it could relate to the setting of male-specific epigenetic information is reviewed and discussed in light of our current knowledge about nuclear structure and functions.

Cell Nucleus↗