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Ovarian Tissue Culture to Visualize Phenomena in Mouse Ovary
Published on: June 19, 2018
Determination of mTOR signal pathway in MMTV-TGFα mice ovary at different ages
T Onel1, E Yıldırım1, S Dogan2
1Department of Histology and Embryology, Yeditepe University Faculty of Medicine, Istanbul, Turkey.
Abstract:
Transforming growth factor alpha (TGFα), a member of the epidermal growth factor (EGF) family, regulates cell proliferation, differentiation, and development, and involves follicular development and viability. In ovaries, TGFα is shown localized in granulosa cells (GCs) of primary follicles, theca cells (TCs) of pre-antral, antral and pre-ovulatory follicles. TGFα overexpression in mouse mammary tumor virus (MMTV-TGFα) transgenic mice causes mammary tumor after 50 weeks. However, follicular development and preservation of the ovarian follicle reserve-mediating follicle stimulating hormone (FSH) response are unknown. Mammalian target of rapamycin (mTOR) is a key regulator for cell proliferation, growth, differentiation, and apoptosis, and important for ovarian folliculogenesis and oocyte maturation. The study aim determines TGFα overexpression during folliculogenesis via mTOR signaling pathway in ovaries from 10-, 18-, 50-, and 82-week-old MMTV-TGFα mice. Histological analysis was performed, along with western blot for mTOR, p-mTOR, P70S6K, PCNA, and Caspase-3, and quantitative RNA (qRT-PCR) for mTOR and P70S6K. Developing follicles number decreased and atretic follicles number increased with aging in MMTV-TGFα mice ovary. Ovaries at 18 and 82 weeks had decreased PCNA and increased Caspase-3 protein expression levels as compared to 10-week ovaries. Protein expression levels of mTOR and p-mTOR decreased gradually from ovaries at 10-18 weeks, increased at 50 weeks and decreased again at 82 weeks. These results indicate that TGFα may be one regulator of healthy follicular development and affect mTOR signaling pathway during ovarian aging. Thus, over-expression of TGFα might lead to reduced ovarian reserve and premature ovarian insufficiency.
Insights
Transforming growth factor alpha (TGFα) overexpression in mice impacts ovarian aging, reducing healthy follicles and affecting the mTOR pathway. This suggests a link to diminished ovarian reserve and premature ovarian insufficiency.
Area of Science:
- Reproductive Biology
- Endocrinology
- Cellular Signaling
Background:
- Transforming growth factor alpha (TGFα), an epidermal growth factor (EGF) family member, is crucial for cell regulation and ovarian follicular development.
- TGFα is present in ovarian granulosa and theca cells, and its overexpression in MMTV-TGFα transgenic mice is known to cause mammary tumors.
- The role of TGFα in follicular development, ovarian reserve, and the associated follicle-stimulating hormone (FSH) response, particularly in the context of aging, remains unclear.
Purpose of the Study:
- To investigate the effects of TGFα overexpression on folliculogenesis and the mammalian target of rapamycin (mTOR) signaling pathway in aging MMTV-TGFα transgenic mouse ovaries.
- To analyze changes in ovarian histology and key protein markers related to cell proliferation, apoptosis, and mTOR signaling across different age groups.
Main Methods:
- Histological analysis of ovaries from 10-, 18-, 50-, and 82-week-old MMTV-TGFα transgenic mice.
- Western blot analysis to quantify protein expression levels of mTOR, phosphorylated mTOR (p-mTOR), P70S6K, PCNA (proliferating cell nuclear antigen), and Caspase-3.
- Quantitative reverse transcription PCR (qRT-PCR) to assess mRNA expression of mTOR and P70S6K.
Main Results:
- A decrease in the number of developing follicles and an increase in atretic follicles were observed with aging in MMTV-TGFα mouse ovaries.
- Ovaries from 18- and 82-week-old mice showed reduced PCNA and increased Caspase-3 protein levels compared to 10-week-old ovaries.
- mTOR and p-mTOR protein levels exhibited a biphasic pattern: decreasing from 10 to 18 weeks, increasing at 50 weeks, and decreasing again at 82 weeks.
Conclusions:
- TGFα overexpression appears to regulate healthy follicular development and influences the mTOR signaling pathway during ovarian aging.
- The observed changes in follicular dynamics and cell survival markers suggest that TGFα overexpression may contribute to reduced ovarian reserve.
- These findings indicate a potential link between TGFα overexpression and the development of premature ovarian insufficiency.
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