This study investigates the endoplasmic reticulum (ER) stress and subsequent apoptosis in duced during somatic cell nuclear transfer (SCNT) process of porcine SCNT embryos. Porcine SCNT and in vitro fertilization (IVF) embryos were sampled at 3 h and 20 h after SCNT or IVF and at the blastocyst stage for mRNA extraction. The x-box binding protein 1 (Xbp1) mRNA and the expressions of ER stress-associated genes were confirmed by RT-PCR or RT-qPCR. Apoptotic gene expression was analyzed by RT-PCR. Before commencing SCNT, somatic cells treated with tunicamycin (TM), an ER stress inducer, confirmed the splicing of Xbp1 mRNA and increased expressions of ER stress-associated genes. In all the embryonic stages, the SCNT embryos, when compared with the IVF embryos, showed slightly increased expression of spliced Xbp1 (Xbp1s) mRNA and significantly increased expression of ER stress-associated genes (p<0.05). In all stages, apoptotic gene expression was slightly higher in the SCNT embryos, but not significantly different from that of the IVF embryos except for the Bax/Bcl2L1 ratio in the 1-cell stage (p<0.05). The result of this study indicates that excessive ER stress can be induced by the SCNT process, which induce apoptosis of SCNT embryos.

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

• Hwa-Yeon Lee(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University)
• Hyo-Kyung Bae(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University)
• Bae-Dong Jung(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University)
• Seunghyung Lee(College of Animal Life Sciences, Kangwon National University)
• Boo-Keun Yang(College of Animal Life Sciences, Kangwon National University)
• Hee-Tae Cheong(College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University) Corresponding Author
• Choon-Keun Park(College of Animal Life Sciences, Kangwon National University)