Epigenetic events in mammalian germ-cell development: reprogramming and beyond

Abstract

The epigenetic profile of germ cells, which is defined by modifications of DNA and chromatin, changes dynamically during their development. Many of the changes are associated with the acquisition of the capacity to support post-fertilization development. Our knowledge of this aspect has greatly increased- for example, insights into how the re-establishment of parental imprints is regulated. In addition, an emerging theme from recent studies is that epigenetic modifiers have key roles in germ-cell development itself--for example, epigenetics contributes to the gene-expression programme that is required for germ-cell development, regulation of meiosis and genomic integrity. Understanding epigenetic regulation in germ cells has implications for reproductive engineering technologies and human health.

Exposure to the widely used herbicide atrazine results in deregulation of global tissue-specific RNA transcription in the third generation and is associated with a global decrease of histone trimethylation in mice

“…Changes in DNA methylation in embryonic germ cells can be associated with changes in histone epigenetic landscape since DNA methylation and histone modifications are functionally linked and can affect gene expression (104). It is also known that the somatic-to-germ line reprogramming causes the activation of retrotransposon elements (105). To explore this possibility we analyzed by qPCR the activity of the most common retro-elements by qPCR.…”

DNA hypermethylation in lung cancer is targeted at differentiation-associated genes

“…We also selected two gene expression time courses of murine gonad development, because it is well-established that germ cells go through unique DNA methylation changes during their development (McLaren, 2000). Multiple waves of demethylation leave the germ cell genome heavily hypomethylated (including the effacement of imprints and reactivation of the inactive X chromosome in females) shortly after primordial germ cells have settled in the genital ridge at E11.5 (Hajkova et al, 2002;Sasaki and Matsui, 2008). The general lack of repression by DNA methylation at this stage might lead to increased non-specific transcription, including low-level expression of somatic genes that would be expected to abate as the germ cells continue their specific differentiation program (including the activation of germ cellspecific genes).…”

Genomic imprinting and its relevance to congenital disease, infertility, molar pregnancy and induced pluripotent stem cell

“…16 However, the differential methylation is erased in primordial germ cells in each generation before the new imprints are set. [17][18][19] THE MECHANISM OF IMPRINT ESTABLISHMENT IN THE GERMLINE The first step of the imprinting cycle, imprint establishment, occurs in male and female gametogenesis. Imprint establishment takes place in growing oocytes in females and prospermatogonia in males.…”