Megan Lim1,2,3, Hannah M Brown4, Ryan D Rose1,5, Jeremy G Thompson1,2,3, Kylie R Dunning6,7,8. 1. Robinson Research Institute, The University of Adelaide, Adelaide, South Australia, Australia. 2. Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide, South Australia, Australia. 3. Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, South Australia, Australia. 4. The Victorian Heart Institute, Monash University, Melbourne, Victoria, Australia. 5. Fertility SA, St. Andrews Hospital, South Terrace, Adelaide, South Australia, Australia. 6. Robinson Research Institute, The University of Adelaide, Adelaide, South Australia, Australia. kylie.dunning@adelaide.edu.au. 7. Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, The University of Adelaide, Adelaide, South Australia, Australia. kylie.dunning@adelaide.edu.au. 8. Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, South Australia, Australia. kylie.dunning@adelaide.edu.au.
Abstract
PURPOSE: Oxygen is vital for oocyte maturation; however, oxygen regulation within ovarian follicles is not fully understood. Hemoglobin is abundant within the in vivo matured oocyte, indicating potential function as an oxygen regulator. However, hemoglobin is significantly reduced following in vitro maturation (IVM). The molecule 2,3-bisphosphoglycerate (2,3-BPG) is essential in red blood cells, facilitating release of oxygen from hemoglobin. Towards understanding the role of 2,3-BPG in the oocyte, we characterized gene expression and protein abundance of bisphosphoglycerate mutase (Bpgm), which synthesizes 2,3-BPG, and whether this is altered under low oxygen or hemoglobin addition during IVM. METHODS: Hemoglobin and Bpgm expression within in vivo matured human cumulus cells and mouse cumulus-oocyte complexes (COCs) were evaluated to determine physiological levels of Bpgm. During IVM, Bpgm gene expression and protein abundance were analyzed in the presence or absence of low oxygen (2% and 5% oxygen) or exogenous hemoglobin. RESULTS: The expression of Bpgm was significantly lower than hemoglobin when mouse COCs were matured in vivo. Following IVM at 20% oxygen, Bpgm gene expression and protein abundance were significantly higher compared to in vivo. At 2% oxygen, Bpgm was significantly higher compared to 20% oxygen, while exogenous hemoglobin resulted in significantly lower Bpgm in the COC. CONCLUSION: Hemoglobin and 2,3-BPG may play a role within the maturing COC. This study shows that IVM increases Bpgm within COCs compared to in vivo. Decreasing oxygen concentration and the addition of hemoglobin altered Bpgm, albeit not to levels observed in vivo.
PURPOSE: Oxygen is vital for oocyte maturation; however, oxygen regulation within ovarian follicles is not fully understood. Hemoglobin is abundant within the in vivo matured oocyte, indicating potential function as an oxygen regulator. However, hemoglobin is significantly reduced following in vitro maturation (IVM). The molecule 2,3-bisphosphoglycerate (2,3-BPG) is essential in red blood cells, facilitating release of oxygen from hemoglobin. Towards understanding the role of 2,3-BPG in the oocyte, we characterized gene expression and protein abundance of bisphosphoglycerate mutase (Bpgm), which synthesizes 2,3-BPG, and whether this is altered under low oxygen or hemoglobin addition during IVM. METHODS: Hemoglobin and Bpgm expression within in vivo matured human cumulus cells and mouse cumulus-oocyte complexes (COCs) were evaluated to determine physiological levels of Bpgm. During IVM, Bpgm gene expression and protein abundance were analyzed in the presence or absence of low oxygen (2% and 5% oxygen) or exogenous hemoglobin. RESULTS: The expression of Bpgm was significantly lower than hemoglobin when mouse COCs were matured in vivo. Following IVM at 20% oxygen, Bpgm gene expression and protein abundance were significantly higher compared to in vivo. At 2% oxygen, Bpgm was significantly higher compared to 20% oxygen, while exogenous hemoglobin resulted in significantly lower Bpgm in the COC. CONCLUSION: Hemoglobin and 2,3-BPG may play a role within the maturing COC. This study shows that IVM increases Bpgm within COCs compared to in vivo. Decreasing oxygen concentration and the addition of hemoglobin altered Bpgm, albeit not to levels observed in vivo.
Authors: Hannah M Brown; Marie R Anastasi; Laura A Frank; Karen L Kind; Dulama Richani; Rebecca L Robker; Darryl L Russell; Robert B Gilchrist; Jeremy G Thompson Journal: Biol Reprod Date: 2014-11-13 Impact factor: 4.285
Authors: Melanie L Sutton-McDowall; Malcolm Purdey; Hannah M Brown; Andrew D Abell; David G Mottershead; Pablo D Cetica; Gabriel C Dalvit; Ewa M Goldys; Robert B Gilchrist; David K Gardner; Jeremy G Thompson Journal: Mol Reprod Dev Date: 2015-02-26 Impact factor: 2.609
Authors: Hannah M Brown; Kylie R Dunning; Melanie Sutton-McDowall; Robert B Gilchrist; Jeremy G Thompson; Darryl L Russell Journal: Reproduction Date: 2016-11-22 Impact factor: 3.906
Authors: Kylie R Dunning; Laura N Watson; Voueleng J Zhang; Hannah M Brown; Adrian K Kaczmarek; Rebecca L Robker; Darryl L Russell Journal: Biol Reprod Date: 2015-03-25 Impact factor: 4.285
Authors: Karen L Kind; Kimberley K Y Tam; Kelly M Banwell; Ashley D Gauld; Darryl L Russell; Anne M Macpherson; Hannah M Brown; Laura A Frank; Daniel J Peet; Jeremy G Thompson Journal: Reprod Fertil Dev Date: 2015-01 Impact factor: 2.311
Authors: M Lim; H M Brown; K L Kind; J Breen; M R Anastasi; L J Ritter; E K Tregoweth; D T Dinh; J G Thompson; K R Dunning Journal: Reprod Fertil Dev Date: 2019-04 Impact factor: 2.311