Eggs age from hypoxia
Scientists have explained the mechanism of aging of eggs
Oleg Lischuk, N+1
American scientists have found out the molecular mechanism of aging of human eggs. It turned out to be associated with hypoxia of the surrounding tissues. The results of the work are published in the journal Molecular Human Reproduction (Molinari et al., Transcriptome analysis of human cumulus cells reveals hypoxia as the main determinant of follicular senescence).
Researchers from Yale University, the University of Connecticut and the Howard Hughes Medical Institute conducted a complete analysis of the transcriptome of the egg-bearing tubercle cells that surround the egg in the follicle and after ovulation. These cells were chosen for the study because access to human eggs is limited, and CSBS play a complex role in their life support and maturation.
The scientists collected 20 samples of CSF from 15 patients (eight under 35 and seven over 40). A full transcriptome analysis of the difference in gene expression in these age periods was performed using sequencing and bioinformatics tools, the data obtained were confirmed by quantitative PCR and immunofluorescence staining.
It turned out that more than 11.5 thousand genes before 35 and after 40 years are expressed the same way, and 45 – differently. Compared with younger women, representatives of the older of the studied groups showed significantly higher activity of genes involved in response to hypoxic stress (NOS2, RORA and NR4A3), vascular growth (NR2F2 and PTHLH), glycolysis (RALGAPA2 and TBC1D4) and cAMP metabolism (PDE4D).
This indicates hypoxia and oxidative stress of follicles in women after 40 years – just at the age when there is a sharp decrease in the quality of eggs. If a similar mechanism is found in the eggs themselves, it will be possible to select the best of them for fertilization by genetic screening of CSB for hypoxic damage. It may also serve as a revision of the ovarian stimulation protocol in age-related patients in order to reduce the residence time of the egg in the hypoxia-prone follicle, the researchers write.
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08.06.2016