Germ-line passage is required for establishment of methylation and expression patterns of imprinted but not of nonimprinted genes.

摘要: Embryonic stem (ES) cells homozygous for a disruption of the DNA (cytosine-5)-methyltransferase gene (Dnmt) proliferate normally with their highly demethylated but die upon differentiation. Expression wild-type Dnmt cDNA in mutant male ES caused an increase methylation bulk and Xist Igf2 genes to normal levels, did not restore imprinted H19 Igfgr. These differentiated vitro contributed substantially adult chimeras. While Xdst was expressed remethylated cells, no restoration expression profile seen H19, Igf2r, or Igf2. This indicates that can faithfully reestablish patterns nonimprinted lack ability those genes. Full monoallelic imposed on lgf2, Igf2r germ-line transmission. results are consistent presence distinct de novo methyltransferase activities during oogenesis spermatogenesis, which specifically recognize absent postimplantation embryo cells.