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Szymańska KJ, Ortiz-Escribano N, Van den Abbeel E, Van Soom A, Leybaert L. Connexin hemichannels and cell death as measures of bovine COC vitrification success. Reproduction 2020; 157:87-99. [PMID: 30390612 DOI: 10.1530/rep-18-0387] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/30/2018] [Indexed: 11/08/2022]
Abstract
Vitrification of immature germinal vesicle-stage oocytes is a promising method in assisted reproduction but is associated with reduced developmental potential and low birth rates. Cumulus-oocyte complexes (COCs) express several connexins that form hexameric hemichannels, which interact head to head to create a gap junction or exist as unopposed free hemichannels. The latter are normally closed but open under stress conditions and may exert detrimental effects. We determined whether minimizing hemichannel opening and cell death during vitrification could improve COC quality. Bovine immature COCs underwent vitrification, storage and warming, followed by dye uptake to assess hemichannel opening and TUNEL staining to detect cell death. Based on these scores, we optimized the procedure by tuning the equilibration time, temperature, cryoprotectant concentration and extracellular Ca2+ concentration and assessed its impact on maturation, cleavage and blastocyst formation after parthenogenetic activation. We found that the major stressor resides in the cooling/warming phase of the vitrification procedure and observed that hemichannel opening and cell death in cumulus cells measure different aspects of cell stress. Optimization of the hemichannel and cell death readouts demonstrated that combined minimal hemichannel opening/cell death gave the highest cleavage rates but had no effect on maturation and blastocyst formation. Neither hemichannel nor cell death optimization performed better than the non-optimized protocol, leading to the conclusion that cell stress factors other than those detected by hemichannel dye uptake or TUNEL positivity are involved.
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Affiliation(s)
| | | | | | - Ann Van Soom
- Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
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Lin X, Beckers E, Mc Cafferty S, Gansemans Y, Joanna Szymańska K, Chaitanya Pavani K, Catani JP, Van Nieuwerburgh F, Deforce D, De Sutter P, Van Soom A, Peelman L. Bovine Embryo-Secreted microRNA-30c Is a Potential Non-invasive Biomarker for Hampered Preimplantation Developmental Competence. Front Genet 2019; 10:315. [PMID: 31024625 PMCID: PMC6459987 DOI: 10.3389/fgene.2019.00315] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 03/21/2019] [Indexed: 01/01/2023] Open
Abstract
Recently, secreted microRNAs (miRNAs) have received a lot of attention since they may act as autocrine factors. However, how secreted miRNAs influence embryonic development is still poorly understood. We identified 294 miRNAs, 114 known, and 180 novel, in the conditioned medium of individually cultured bovine embryos. Of these miRNAs, miR-30c and miR-10b were much more abundant in conditioned medium of slow cleaving embryos compared to intermediate cleaving ones. MiR-10b, miR-novel-44, and miR-novel-45 were higher expressed in the conditioned medium of degenerate embryos compared to blastocysts, while the reverse was observed for miR-novel-113 and miR-novel-139. Supplementation of miR-30c mimics into the culture medium confirmed the uptake of miR-30c mimics by embryos and resulted in increased cell apoptosis, as also shown after delivery of miR-30c mimics in Madin-Darby bovine kidney cells (MDBKs). We also demonstrated that miR-30c directly targets Cyclin-dependent kinase 12 (CDK12) through its 3′ untranslated region (3′-UTR) and inhibits its expression. Overexpression and downregulation of CDK12 revealed the opposite results of the delivery of miRNA-30c mimics and inhibitor. The significant down-regulation of several tested DNA damage response (DDR) genes, after increasing miR-30c or reducing CDK12 expression, suggests a possible role for miR-30c in regulating embryo development through DDR pathways.
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Affiliation(s)
- Xiaoyuan Lin
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Evy Beckers
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Séan Mc Cafferty
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Yannick Gansemans
- Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | | | | | - João Portela Catani
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Filip Van Nieuwerburgh
- Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Dieter Deforce
- Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Petra De Sutter
- Department of Uro-Gynaecology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Ann Van Soom
- Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Luc Peelman
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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