Insulin-like growth factor II (IGF2) and H19 genes are mutually imprinted genes which may be responsible for abnormalities in the cloned fetuses and offspring. This study was performed to identify putative differentially methylated regions (DMRs) of porcine H19 locus and to explore its genomic imprinting in in vitro fertilized (IVF) and somatic cell nuclear transferred (SCNT) embryos. Based on mice genomic data, we identified DMRs on H19 and found porcine H19 DMRs that included three CTCF binding sites. Methylation patterns in IVF and SCNT embryos at the 2-, 4-, 8～16-cells and blastocyst stages were analyzed by BS (Bisulfite Sequencing)-PCR. The CpGs in CTCF1 was significantly unmethylated in the 2-cell stage IVF embryos. However, the 4- (29.1%) and 8～16-cell (68.2%) and blastocyst (48.2%) stages showed higher methylation levels (p<0.01). On the other hand, SCNT embryos were unmethylayted (0～2%) at all stages of development. The CpGs in CTCF2 showed almost unmethylation levels at the 2-, 4- and 8～16-cell and blastocyst stages of development in both IVF (0～14.1%) and SCNT (0～6.4%) embryos. At all stages of development, CTCF3 was unmethylated in IVF (0～17.3%) and SCNT (0～1.2%) embryos except at the blastocyst stage (54.5%) of IVF embryos. In conclusion, porcine SCNT embryos showed an aberrant methylation pattern comprised to IVF embryos. Therefore, we suggest that the aberrant methylation pattern of H19 loci may be a reason for increased abnormal fetus after embryo transfer of porcine SCNT embryos.

ABSTRACT   INTRIDUSTION   MATERIALS AND METHODS    oocyte Retrieval and In Vitro Maturation    In Vitro Fertilization(IVF) of Oocytes    Preparation of Donor Cells for Nuclear Transfer    Somatic Cell Nuclear Transfer(SCNT) of Oocytes    Comparative Sequencing    Genomic DNA Isolation    Bisulfite(BS) Treatment and Polymerase Chain Reaction(PCR)    Cloning and sequencing    Experimental Designs    Statistical Analysis   RESULTS    Sequence Homology    Bisulfite Sequencing Analysis of Putative DMRs    Bisulfite Sequencing Analysis of Pocine IVF and SCNT Embryos   DISCUSSION   REFERENCES

• Young-Bin Im(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Dong-Wook Han(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Mukesh Kumar Gupta(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Sang Jun Uhm(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Young Tae Heo(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Jin-Hoi Kim(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Chankyu Park(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology)
• Hoon Taek Lee(Department of Biotechnology, Bio-Organ Research Center/Institute of Biomedical Science and Technology) Corresponding author