The role of cytochrome c in mitochondrial metabolism of human oocytes
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We investigated the biochemical composition of specific organelles in human oocyte cells at various maturation stages (GV, immature MI, MII with the first polar body, MII with giant polar body, and vacuoles) using Raman imaging. The structures analyzed included the nucleus, zona pellucida, perivitelline space, polar body, mitochondria, and cytoplasm. Raman imaging combined with chemometric classification via Cluster Analysis facilitated a comprehensive biochemical analysis of the proteomic, lipidomic, and DNA profiles of the human oocyte. Our findings indicate that cytochrome c is a crucial protein in oocyte mitochondria, essential for both cellular respiration (via oxidative phosphorylation) and apoptosis. Effective oocyte cell functioning requires cytochrome c in its redox-balanced forms: reduced and oxidized. The oxidized form of cytochrome c plays a pivotal role in the electron transport chain, enabling proper electron shuttling between complex III, cytochrome c , and complex IV. This process ensures controlled oxidative phosphorylation and ATP production, which are vital for most steps in oocyte maturation.
Background
In spite of progress in the identification of the fertile/infertile human oocytes in the recent decades, our understanding of molecular mechanisms occurring in the female reproductive cells did not make significant progress.
Objective
The present study aimed to develop our knowledge on mitochondrial metabolism in oocyte cells.
Results
Biochemical human oocyte analysis of proteomic-lipidomic-DNA profile by using Raman imaging combined with chemometric classification method of Cluster Analysis has been obtained. Our results show that cytochrome c is a key protein in oocyte mitochondria that is needed to maintain life (respiration via oxidative phosphorylation) and cell death (apoptosis).
Materials and Methods
In this experimental study, the nine fresh human native live oocytes from six donors collected in Salve Medica, Lodz, Poland have been investigated. The fingerprint and high-frequency region were evaluated by using Raman spectroscopy and imaging from 400 to 3500 cm -1 . The principal component analysis method was used to visualize the difference in the Raman spectra of oocytes at different stage of maturation. The study was approved by the Bioethical Committee of the Medical University in Lodz, Poland (No RNN/83/23/KE). Written informed consent was obtained from all patients who voluntarily participated in the study. All procedures were conducted in accordance with the guidelines of the Declaration of Helsinki (2013).
