Determination of tert gene expressions in the postnatal mouse ovarian tissues

Objective: Telomeres are repetitive DNA sequences found at the ends of eukaryotic chromosomes. Due to biological aging mammalian ovaries are getting aged and telomeres shorten during this process. The molecular background of telomeres shortening is not fully understood. The aim of this study was to determine the genes involved in elongating telomeres and maintaining the integrity of telomeres in the mouse ovaries at different ages of postnatal life. Method: Five groups were formed based on the ovarian development terms in mice as follows: early (1- and 2-week old), young (3- and 4-week old), adult (5- and 6-week old), late adult (16- and 18-week old) and aged (52-, 60- and 72-week old). Tert, Terc, Trf1, Trf2 and Pot1a mRNA expression has been determined by qRT-PCR and their protein expression was characterized by using immunohistochemistry in the mouse ovaries. The statistical significance was evaluated with one way ANOVA test. Results: Tert expression in early group was found to be significantly higher than that of young, adult, late adult and aged groups. The Terc expression decreased from early to aged groups. Although Trf1 expression did not differ among groups, Trf2 expression was at the lowest levels in the late adult groups when compared to young and adult groups. Pot1a expression in the aged group was significantly higher than that of in the late adult groups. The relative TERT expression among the groups decreased from early to aged groups, but this change was not found significant. No statistically significant difference was found in TRF1 expression among groups. TRF2 expression was significantly lower in the early group in comparision to the aged group. The POT1 expression decreased in the late adult groups and increased in the aged group. Conclusion: The expressional changes in Tert, Terc, Trf2 and Pot1a genes are thought to have an effect on telomere shortening during ovarian aging. We believe that more detailed molecular biological studies are needed to determine the effect of these genes on telomere length Keywords: telomere, telomerase, ovary, aging.