DNA methylation status of H19 and Xist genes in lungs of somatic cell nuclear transfer bovines

In somatic cell nuclear transfer (SCNT) technologies, the donor cell’s nuclei need to be epigenetically reprogrammed for embryonic development. The incomplete reprogramming of donor cell nuclei has been implicated as a primary reason for the low efficiency of SCNT. DNA methylation is a major epigenetic modification of the genome that regulates crucial aspects of genome function, including establishment of genomic imprinting. In order to make sure whether the DNA methylation reprogramming is efficient in SCNT animals, we analyzed the DNA methylation status of two imprinting genes, H19 and Xist, in lungs of deceased SCNT bovines that died within 48 h of birth using bisulfite sequencing analysis. Our findings demonstrated that cloned bovines showed significantly lower DNA methylation of H19 than controls (P<0.05), and three tested CpGs sites (1, 2, 3) exhibited unmethylation in one cloned bovine (9C3); however, Xist showed similar DNA methylation levels between clones and controls, and both showed hypermethylation (96.11% and 86.67%). Supported by the National High Technology Research and Development Program of China (Grant No. 2001AA213091) and Natural Science Foundation of Hebei Province (Grant No. C2006001032)