Examination of DNA methyltransferase expression in cloned embryos reveals an essential role for Dnmt1 in bovine development

摘要: In studies of somatic cell nuclear transfer (SCNT), the ability factors within oocyte to epigenetically reprogram transferred nuclei is essential for embryonic development clone proceed. However, irregular patterns X-chromosome inactivation, abnormal expression imprinted genes, and genomic DNA hypermethylation are frequently observed in reconstructed embryos, suggesting abnormalities this process. To better understand epigenetic events underlying SCNT reprogramming, we sought determine if methylation levels cloned embryos result from a failure properly transcription versus differential biochemical regulation methyltransferase family enzymes (DNMTs) between nuclei. address question, conducted real-time quantitation Dnmt transcripts bovine preimplantation generated though vitro fertilization (IVF), parthenogentic activation, SCNT. By 8-cell stage, encoding Dnmt1 become significantly down-regulated likely response state hypermethylation, while de novo methyltransferases maintain an pattern indistinguishable their IVF parthenote counterparts. Depletion embryonic/maternal using short-interfering RNAs, able lower levels, resulted developmental arrest at 8/16-cell stage. contrast, derived stable, Dnmt1-depleted donor line develop blastocyst but failed carry term. Our results indicate role during development, suggest proper transcriptional reprogramming gene embryos. Mol. Reprod. Dev. 78:306–317, 2011. © 2011 Wiley-Liss, Inc.