Caspase‐2_L, caspase‐9, and caspase‐3 during in vitro maturation and fragmentation of the mouse oocyte

Abstract

Several studies have shown that apoptotic pathways control fragmentation of unfertilized ovulated oocyte, induced by doxorubicin. But very few have investigated the basis of this process, from prophase I to later stages. Our results revealed the presence of caspase-2 L , caspase-9, and caspase-3 in their zymogen and cleaved forms in the oocyte before meiosis resumption. Caspase-2 L and caspase-9 were detected in the nucleus of GV-oocytes in a distribution related to chromatin configuration. The inhibition of caspase activity by Z-VAD-fmk accelerated the transition from metaphase I to metaphase II, and caspase-9 and caspase-3 were detected along the meiotic spindle. Surprisingly, Western blot analysis revealed that the three cleaved caspases were present in similar amounts in healthy and fragmented oocytes and caspase inhibition did not prevent doxorubicin-induced apoptosis. Our results suggest that, if cleaved, caspases may be dispensable for final oocyte death and they could be involved in regulating the maturation process.

Features of programmed cell death in intact Xenopus oocytes and early embryos revealed by near-infrared fluorescence and real-time monitoring

“…Sublethal caspase activity has been reported in Xenopus oocytes as well as in human preimplantation embryos34,35, and we hypothesize that our observations reflect the accumulation of minimal amounts of active caspases present at any given time that become significant only in summation. It is unclear whether these minimal amounts of caspase activity are important for development or are simply an inexorable consequence of rapid cell division that is tolerated by the embryo.…”

C-phycocyanin protects against low fertility by inhibiting reactive oxygen species in aging mice

“…All oocytes from in vivo or in vitro maturation were examined for PB1 extrusion and fragmentation. The criteria for fragmentation evaluation were based on previous reports [ 61 , 62 ]. Body weight and organ (ovary, liver, and spleen) wet weight were measured and recorded at the end of treatment, and ovaries were kept frozen at −80°C for further experiments.…”

Analysis of different cell death processes of prepubertal rat oocytes in vitro

“…Most evidence indicates that apoptosis is the main process of granulosa cell death during follicular atresia [31,32]; however in ovaries of birds it was found that autophagy and necrosis also participate in cell disposal [3,4]. Oocyte death during atresia was also attributed to apoptosis in several animals [33][34][35][36][37][38].…”