title: Cathepsin B activity has a crucial role in the developmental competence of bovine cumulus-oocyte complexes exposed to heat shock during in vitro maturation.
abstract: Cathepsin B was found to be correlated inversely with the quality of bovine oocytes and embryos. The aims of this study were to evaluate i) the relationship between heat shock during in vitro maturation (IVM) of bovine cumulus-oocyte complexes (COCs) and cathepsin B activity in relation to apoptosis and ii) the effect of supplementation of cathepsin B inhibitor (E-64) during IVM of heat-shocked COCs on embryonic development. After IVM at 38.5 °C for 22 h (control group) or at 38.5 °C for 5 h followed by 41 °C for 17 h (heat shock group) either with or without 1 μM E-64, activities and protein expression of cathepsin B and caspase 3 were evaluated as well as TUNEL staining. After IVF, developmental rate, total cell number, and the percentage of apoptotic cells in blastocysts were evaluated on day 8 (day 0, IVF day). Heat-shocked IVM COCs showed significantly high activities and expressions of both cathepsin B, and caspase 3 accompanied by a significant increase in number of TUNEL-positive cells. Addition of E-64 significantly decreased the activities of cathepsin B and caspase 3, and TUNEL-positive cells in heat-shocked IVM COCs. Moreover, addition of 1 μM E-64 during IVM under heat shock conditions significantly improved both developmental competence and quality of the produced embryos. These results indicate that heat shock induction of cathepsin B is associated with apoptosis of COCs, and inhibition of cathepsin B activity can improve the developmental competence of heat-shocked COCs during IVM.
authors.affiliation: Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization (NARO), 2421 Suya, Kumamoto 861-1192, 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: M
authors.initials: M
authors.lastname: Kawahara
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; D017209:Apoptosis; D001755:Blastocyst / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D002401:Cathepsin B / Q000378:metabolism*; D002417:Cattle; D054885:Cumulus Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D005307:Fertilization in Vitro; D018869:Heat-Shock Response; D006358:Hot Temperature; D020287:In Situ Nick-End Labeling; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D006080:Ovarian Follicle / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy
chemical_list: D015853:Cysteine Proteinase Inhibitors; D002401:Cathepsin B; D007930:Leucine; C024974:E 64