Effect of autophagy induction and cathepsin B inhibition on developmental competence of poor quality bovine oocytes

Abstract

The present study investigated the effect of autophagy induction and cathepsin B (CTSB) inhibition on developmental competence of poor quality oocytes. Bovine cumulus oocyte complexes (COCs) were classified as good or poor according to their morphology. Autophagy activity was detected in good and poor germinal vesicle (GV) oocytes. Then E-64, a CTSB inhibitor, rapamycin (Rapa), an autophagy inducer, and combined administration was achieved during in vitro maturation (IVM) of poor quality COCs followed by detection of autophagy activity. In the next experiment, E-64, Rapa, and E64 + Rapa, were added during IVM to good and poor quality COCs followed by in vitro fertilization and culture for 8 days to investigate whether inhibition of CTSB and/or induction of autophagy improve embryonic development and quality. Autophagy activity was significantly lower in poor quality GV oocytes than in good quality ones. E-64, Rapa and E-64 + Rapa treatment during IVM significantly increased autophagy activity in poor quality oocytes. Addition of Rapa in good quality COCs did not increase the blastocyst rate, whereas E-64 increased the blastocyst rate and total cell number (TCN) with decreasing TUNEL-positive cells. In contrast, Rapa treatment in poor quality COCs significantly increased the blastocyst rate and TCN with decreasing TUNEL-positive cells. These results indicate oocyte quality has different responses to intracellular autophagy induction and CTSB activity control by potential autophagy and catabolic status, however, synergetic effect of autophagy induction and CTSB inhibition can increase developmental competence of both good and poor quality COCs, especially rescue effect in poor quality COCs.

Transcriptome profiles of pre‐pubertal and adult in vitro matured ovine oocytes obtained from FSH‐stimulated animals

“…Cathepsin B (CTSB) is a lysosomal cysteine protease that plays a key role in the initiation of apoptosis pathways by directly or indirectly activating the promoter caspases (Barrett & Kirschke, 1981;Vancompernolle et al, 1998). Inhibition of CTSB activity can improve the development of preimplantation embryos in cattle and pigs (Balboula et al, 2010(Balboula et al, , 2013Li, Balboula, et al, 2020;Li, Lu, et al, 2020). In this study, CSTB was down-regulated in lamb oocytes, which could contribute to the low competence of lamb oocytes.…”

Effect of E-64 Supplementation during In Vitro Maturation on the Developmental Competence of Bovine OPU-Derived Oocytes

“…E-64 (E3132) was dissolved in phosphate-buffered saline (PBS) and then added to TCM-199 medium to a final concentration of 1 μM. The final concentration of E-64 was selected based on our previous publications [ 14 , 15 , 21 , 22 ]…”

Regulation of autophagy by microRNAs in human breast cancer

“…A number of tethers (HOPS, ATG14L and TECPR1), motor adaptors (FYCO1, PLEKHM1/2 and RILP) will also be involved in mediating the fusion process [ 51 ]. As the fusion completes, the autophagosome contents will be released and these substances will be degraded in an acidic environment containing enzymes like cathepsin B, cathepsin L and other hydrolytic enzymes [ 52 , 53 ]. The digested substances will then be released from the autolysosome via protein channels and it is now can be used for anabolism or other cellular processes [ 16 , 52 , 53 ].…”

“…As the fusion completes, the autophagosome contents will be released and these substances will be degraded in an acidic environment containing enzymes like cathepsin B, cathepsin L and other hydrolytic enzymes [ 52 , 53 ]. The digested substances will then be released from the autolysosome via protein channels and it is now can be used for anabolism or other cellular processes [ 16 , 52 , 53 ]. The ultimate fate of the autolysosome, however, is still poorly understood, and it is unclear whether it will dissociate into lysosome and autophagosome after the digestion process is completed [ 39 ].…”