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KMID : 1007320070130030173
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Journal of the Korean Society of Menopause
2007 Volume.13 No. 3 p.173 ~ p.183
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Role of JNK1 and JNK2 in Murine Ovarian Germ Cell Apoptosis
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Kim Mee-Ran
Choi Yoon-Kyong
Song Jae-Yeon
Shin Hyun-Mi
Jung Jae-Eun
Lim Young-Taik
Kim Jang-Heub
Kim Jin-Hong
Lew Young-Ok
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Abstract
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Objectives: Each female is endowed with a finite numbers of oocytes, which when depleted leads to ovarian senescence, the menopause. The objective of this study was to investigate the role of JNK1 and JNK2 in murine ovarian germ cell apoptosis.
Methods: Murine oocytes were retrieved by superovulation of female C57BL/6 mice at the age of 21∼24 days. At 10 minutes after UV irradiation, immunocytochemistry was performed. Ovarian granulosa cells were cultured from antral follicles. At the 24 hours of the culture period, UV was irradiated on culture dishes. After 30 minutes, protein was extracted and western blotting done. Same procedures were performed with Hepa 1c1c7 cells. Serial ovarian sections (8μm) were stained with modified Lee’s picric methyl blue, and we estimated the numbers of oocyte-containing primordial, primary and small preantral follicles of female mice at day 4 and day 42 postpartum. Ovarian granulosa cells were cultured from female wild-type and JNK1 / or JNK2 / mice. The granulosa cells were fixed at 2, 4, 6 hours after UV irradiation and stained with Hoescht 33342, and then evaluated for characteristics of apoptosis under fluorescence microscopy.
Results: After UV irradiation, oocytes showed intense signal of phospho-JNK. In ovarian granulosa cells, JNK was activated to phospho-JNK after UV irradiation, but not in Hepa 1c1c7 cells. There was no difference in oocyte counts between wild type and JNK1 / or JNK2 / at day 4 and day 42 postpartum. The incidence of apoptosis of ovarian granulosa cells from wild type were 13.0±3.3%, 22.2±12.8%, 32.0±10.4%, 42.9± 11.3% after 0, 2, 4, 6 hour of UV irradiation, respectively. The incidences were 10.5±4.1%, 18.3±9.1%, 24.8 ±9.1%, 29.5±12.4%, respectively in granulosa cells from JNK1 / mice. These results showed only a partial suppression of apoptosis in granulosa cells from JNK1 / mice, however, it was not statistically significant. There was no significant difference in the rate of apoptosis of granulosa cells after UV irradiation between wild type and JNK2 / mice.
Conclusion: JNK1 and JNK2 are recognized as critical regulators of various aspects of mammalian physiology, including cell proliferation, cell survival and cell death. This study showed that UV irradiation caused activation of JNK in murine oocytes and granulosa cells of ovary. In murine ovary, JNK1 and JNK2 may be redundant or have compensatory role to each other in apoptosis. These findings may help to elucidate the one of mechanisms for acceleration of oocyte depletion in women with premature menopause.
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KEYWORD
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Apoptosis, Granulosa cell, JNK1, JNK2, Ovary
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