Intracellular cathepsin B activity is inversely correlated with the quality and developmental competence of bovine preimplantation embryos

Abstract

Recently, the activity of cathepsins B was found to be correlated inversely with the developmental competence of bovine oocytes. In this study, we investigated (1) the role of intracellular cathepsin B expression and developmental competence as well as the quality of bovine preimplantation embryos, and (2) the effect of cathepsin B inhibitor (E-64) during in vitro culture (IVC) on the development and quality of bovine embryos. After in vitro fertilization (IVF) followed by IVC for 7 days, good and poor quality embryos classified by morphology and developmental rate on days 2, 4, and 7 were assessed for cathepsin B expression and activity. To investigate the effect of cathepsin B inhibition on embryonic development, putative zygotes were cultured with or without E-64, followed by evaluation of cleavage and blastocyst rates on days 2 and 7, respectively. Embryonic quality was evaluated by both TUNEL staining and total cell number in day-7 blastocysts. In each developmental stage, cathepsin B expression and activity were significantly higher in poor quality embryos than good quality ones. Moreover, addition of E-64 during IVC significantly increased both the blastocyst rate and the total cell number. TUNEL staining revealed that inhibition of cathepsin B significantly decreased the number of apoptotic nuclei in day-7 blastocysts. These results indicate that cathepsin B activity can be useful as a marker for inferior quality embryos. Moreover, inhibition of cathepsin B greatly improves the developmental competence of preimplantation embryos and increases the number of good quality embryos.

Cathepsin B activity has a crucial role in the developmental competence of bovine cumulus–oocyte complexes exposed to heat shock during in vitro maturation

“…Bettegowda et al (2008) first reported that cumulus cells of low developmental competence oocytes showed higher expression of cathepsin B mRNA than those of high developmental competence oocytes (Bettegowda et al 2008). Moreover, our previous studies clearly showed that cathepsin B activity is inversely correlated with the quality of bovine COCs and embryos by the higher activity and protein expression of cathepsin B in poor-quality in vitro matured oocytes and embryos than in good-quality ones (Balboula et al 2010a(Balboula et al , 2010b. Furthermore, cathepsin B was found to impair the oocyte and embryo developmental competence by possible stimulation of the apoptotic pathway (Balboula et al 2010a(Balboula et al , 2010b.…”

“…Moreover, our previous studies clearly showed that cathepsin B activity is inversely correlated with the quality of bovine COCs and embryos by the higher activity and protein expression of cathepsin B in poor-quality in vitro matured oocytes and embryos than in good-quality ones (Balboula et al 2010a(Balboula et al , 2010b. Furthermore, cathepsin B was found to impair the oocyte and embryo developmental competence by possible stimulation of the apoptotic pathway (Balboula et al 2010a(Balboula et al , 2010b. In this study, the significant decrease in TUNEL apoptosis in heat-shocked bovine COCs after the addition of cathepsin B inhibitor (E-64) to the IVM medium clearly showed that cathepsin B has one of the key roles in inducing apoptosis during heat shock of bovine COCs.…”

“…Furthermore, cathepsin B increases in poor-quality bovine oocytes and embryos, which is associated with low developmental competence, than in good-quality ones. Supplementation of the IVM medium with cathepsin B inhibitor (E-64) improved the developmental competence of bovine COCs possibly by regulation of the apoptotic pathway (Bettegowda et al 2008, Balboula et al 2010a, 2010b. However, there is no available data about the possible role of cathepsin B during oocyte maturation and subsequent development under heat shock condition.…”

Bovine Cumulus Cells Protect Maturing Oocytes from Increased Fatty Acid Levels by Massive Intracellular Lipid Storage

“…The primers used for analysis of the relative mRNA expression of the genes cathepsin B (CTSB), placenta-specific 8 (PLAC8), and prostaglandin-endoperoxide synthase 2 (PTGS) as markers for blastocyst quality [38,39], and of the reference genes H 2 A histone family, member Z (H2AFZ) and phosphoglycerokinase (PGK) are summarized in Table 1. Each primer of a pair was located on a Bio-Rad Laboratories, Hercules, CA).…”

Cathepsin B inhibitor improves developmental competency and cryo-tolerance of in vitro ovine embryos

“…It has also been reported that E-64 treatment after IVF followed by IVC for 6 days significantly improved developmental competences and increased number of good quality bovine embryos [23]. On the other hand, Min et al (2014) reported that treatment during IVC with E-64 (0.1 and 0.5 μM) significantly improves developmental rates without any noticeable effect on cleavage rate [24].…”