title: 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.
authors.affiliation: National Agricultural Research Center for Kyushu Okinawa Region, Suya, Kumamoto, Japan.
authors.forename: A Z
authors.initials: AZ
authors.lastname: Balboula
authors.forename: K
authors.initials: K
authors.lastname: Yamanaka
authors.forename: M
authors.initials: M
authors.lastname: Sakatani
authors.forename: A O
authors.initials: AO
authors.lastname: Hegab
authors.forename: S M
authors.initials: SM
authors.lastname: Zaabel
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001755:Blastocyst / Q000166:cytology / Q000201:enzymology* / Q000502:physiology*; D002401:Cathepsin B / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002417:Cattle; D048708:Cell Growth Processes / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D042541:Intracellular Space / Q000378:metabolism; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; D002401:Cathepsin B; D007930:Leucine; C024974:E 64