A Cathepsin B Inhibitor,E-64, Improves the Preimplantation Development of Bovine Somatic Cell Nuclear Transfer Embryos

Bovine somatic cell nuclear transfer (SCNT) is an important and powerful tool for basicresearch and biomedical and agricultural applications, however, the efficiency of SCNT hasremained extremely low. In this study, we investigated the effects of cathepsin Binhibitor (E-64) supplementation of culture medium on in vitrodevelopment of bovine SCNT embryos. We initially used three concentrations of E-64 (0.1,0.5, 1.0 μm), among which 0.5 μm resulted in the highest rate of blastocysts production after invitro fertilization (IVF), and was therefore used for further experiments.Blastocyst development of SCNT embryos in the E-64 treatment group also increased relativeto the control. Moreover, the cryosurvival rates of IVF and SCNT blastocysts wereincreased in E-64 treatment groups when compared with the control. On the other hand, wefound that IVF and SCNT blastocysts derived from E-64-treated groups had increased totalcell numbers and decreased apoptotic nuclei. Furthermore, assessment of the expression ofapoptosis-related genes (Bax and Bcl-xL) in bovine IVF and SCNT blastocysts treated withE-64 by real-time RT-PCR analysis revealed suppressed expression of the pro-apoptotic geneBax and stimulated expression of the anti-apoptotic gene Bcl-xL. Taken together, thesefinding indicate that addition of E-64 to embryo culture medium may have importantimplications for improving developmental competence and preimplantation quality in bovineIVF and SCNT embryos.