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Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro

BACKGROUND: In human IVF, embryos cultured with a lower O(2) tension (5%) can give rise to higher success rates when compared with normoxic conditions (20%). However, the mechanisms behind the beneficial effects of reduced oxygen tension in embryogenesis remain unclear. The aim of this study was to...

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Autores principales: Ma, Yun-Yi, Chen, Huei-Wen, Tzeng, Chii-Ruey
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520294/
https://www.ncbi.nlm.nih.gov/pubmed/28728562
http://dx.doi.org/10.1186/s13048-017-0344-1
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author Ma, Yun-Yi
Chen, Huei-Wen
Tzeng, Chii-Ruey
author_facet Ma, Yun-Yi
Chen, Huei-Wen
Tzeng, Chii-Ruey
author_sort Ma, Yun-Yi
collection PubMed
description BACKGROUND: In human IVF, embryos cultured with a lower O(2) tension (5%) can give rise to higher success rates when compared with normoxic conditions (20%). However, the mechanisms behind the beneficial effects of reduced oxygen tension in embryogenesis remain unclear. The aim of this study was to evaluate the expression of oxygen related and antioxidant genes and mitochondrial function in mouse embryo cultured under hypoxic and normoxic conditions, to investigate the beneficial effect of low oxygen tension in preimplantation embryogenesis. METHODS: Two-cell ICR mouse embryos were cultured to blastocysts under different oxygen tension (3% and 20%). The gene expression of oxygen-related proteins (hypoxia-inducible factor, HIF), HIF targets (vascular endothelial growth factor, VEGF; glucose transporter 3, GLUT-3) and antioxidants (manganese superoxide dismutase, MnSOD; peroxiredoxin 5, PRDX5) were assessed using quantitative RT-PCR and implantation-related protein (Leukemia Inhibitory Factor Receptor, LIFR) was validated by immunofluorescence. Apoptosis, mitochondrial membrane potential (MtMP) and ROS levels were measured by TUNEL, JC-1 and DCFDA assays, respectively. RESULTS: Blastocyst development rate (92.3% vs. 79.4%) and hatch rate (80% vs. 70.4%) were both higher in embryos cultured in 3% O(2) than in 20% O(2). The transcription levels of MnSOD, PRDX5, VEGF and GLUT-3 also significantly increased in 3% O(2) compared with 20% O(2) (P < 0.05). Immunofluorescence showed that the intensity of staining for HIF-2α, MnSOD and LIFR were higher in 3% O(2). Blastocysts cultured under 3% O(2) exhibited significantly higher MtMP compared with 20% O(2). ROS and Apoptosis levels were significantly higher in the 20% O(2) group than in the 3% O(2) group (P < 0.05). CONCLUSIONS: Low O(2) tension may improve embryo viability by increasing expression of antioxidant enzymes and glucose transporter activities. It provides an environment conducive to viability by upregulation of LIFR/VEGF and increased MtMP which could enhance implantation potential and reduce apoptosis in mouse blastocyst. These effects may be initiated and regulated by HIF-2α, a key mediator in a hypoxic environment.
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spelling pubmed-55202942017-07-21 Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro Ma, Yun-Yi Chen, Huei-Wen Tzeng, Chii-Ruey J Ovarian Res Research BACKGROUND: In human IVF, embryos cultured with a lower O(2) tension (5%) can give rise to higher success rates when compared with normoxic conditions (20%). However, the mechanisms behind the beneficial effects of reduced oxygen tension in embryogenesis remain unclear. The aim of this study was to evaluate the expression of oxygen related and antioxidant genes and mitochondrial function in mouse embryo cultured under hypoxic and normoxic conditions, to investigate the beneficial effect of low oxygen tension in preimplantation embryogenesis. METHODS: Two-cell ICR mouse embryos were cultured to blastocysts under different oxygen tension (3% and 20%). The gene expression of oxygen-related proteins (hypoxia-inducible factor, HIF), HIF targets (vascular endothelial growth factor, VEGF; glucose transporter 3, GLUT-3) and antioxidants (manganese superoxide dismutase, MnSOD; peroxiredoxin 5, PRDX5) were assessed using quantitative RT-PCR and implantation-related protein (Leukemia Inhibitory Factor Receptor, LIFR) was validated by immunofluorescence. Apoptosis, mitochondrial membrane potential (MtMP) and ROS levels were measured by TUNEL, JC-1 and DCFDA assays, respectively. RESULTS: Blastocyst development rate (92.3% vs. 79.4%) and hatch rate (80% vs. 70.4%) were both higher in embryos cultured in 3% O(2) than in 20% O(2). The transcription levels of MnSOD, PRDX5, VEGF and GLUT-3 also significantly increased in 3% O(2) compared with 20% O(2) (P < 0.05). Immunofluorescence showed that the intensity of staining for HIF-2α, MnSOD and LIFR were higher in 3% O(2). Blastocysts cultured under 3% O(2) exhibited significantly higher MtMP compared with 20% O(2). ROS and Apoptosis levels were significantly higher in the 20% O(2) group than in the 3% O(2) group (P < 0.05). CONCLUSIONS: Low O(2) tension may improve embryo viability by increasing expression of antioxidant enzymes and glucose transporter activities. It provides an environment conducive to viability by upregulation of LIFR/VEGF and increased MtMP which could enhance implantation potential and reduce apoptosis in mouse blastocyst. These effects may be initiated and regulated by HIF-2α, a key mediator in a hypoxic environment. BioMed Central 2017-07-20 /pmc/articles/PMC5520294/ /pubmed/28728562 http://dx.doi.org/10.1186/s13048-017-0344-1 Text en © The Author(s). 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Ma, Yun-Yi
Chen, Huei-Wen
Tzeng, Chii-Ruey
Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
title Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
title_full Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
title_fullStr Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
title_full_unstemmed Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
title_short Low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
title_sort low oxygen tension increases mitochondrial membrane potential and enhances expression of antioxidant genes and implantation protein of mouse blastocyst cultured in vitro
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520294/
https://www.ncbi.nlm.nih.gov/pubmed/28728562
http://dx.doi.org/10.1186/s13048-017-0344-1
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