Recent studies on Mest and Peg3 demonstrate that these genes with paternal allele-specific expression in the brain affect maternal behaviour. This restores expression to a previously silent allele of an imprinted gene. The model makes it possible to investigate mechanisms by which a somatic nucleus acquires a pluripotent state. The maternal allele of the H19 imprinted gene is preferentially expressed. The transgene, when introduced into Drosophila, led to the identification of a 1.2kb cis element which acts as a bi-directional gene silencer.
Imprinted genes affect aspects of development and behaviour in mammals.
Mutations in the Peg3 and Mest genes affect maternal behaviour. Both genes are expressed only when inherited from the father, whereas the maternal allele is repressed. These studies have implications for evolutionary theories of genomic imprinting, and for the role of paternally inherited genes affecting behaviour. Embryonic germ cells induce epigenetic reprogramming of somatic nucleus in hybrid cells. EMBO J. 16, 6510-6520.