Epigenetic silencing of gene expression helps to regulate the onset of puberty in female rats, reports a paper published online this week in Nature Neuroscience. The onset of puberty is highly variable, particularly in humans, and is believed to be influenced by both genetic and environmental factors. Epigenetic mechanisms, such as DNA methylation, are known to be modulated by the environment and so this study represents a new potential convergence point for the genetic and environmental influences on the timing of puberty.
Alejandro Lomniczi, Sergio Ojeda and colleagues report blocking the process of DNA methylation - where methyl groups are chemically attached to specific segments of DNA in order to prevent the expression of certain genes - can delay the onset of puberty in female rats. Careful analysis of the differences in DNA methylation between pre- and post-pubescent rats revealed that two members of the Polycomb group (PcG) of transcriptional silencers (a complex of proteins which inhibit the expression of other genes) were repressed by methylation at the initiation of puberty. The authors further show that these two proteins can, in turn, inhibit the expression of the gene Kiss1, which is known to be essential for the commencement of puberty.
These findings suggest a mechanism wherein methylation of these PcG genes reduces their expression, allowing for the levels of Kiss1 to be increased, signaling the initiation of puberty in females.