The interaction of steroids with Rana pipiens oocytes in the induction of maturation

Smith, L.Dennis; Ecker, R.E.

doi:10.1016/0012-1606(71)90029-7

Cited by 382 publications

(103 citation statements)

References 16 publications

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“…1). These results are consistent with earlier reports that androgens are secreted by Xenopus ovarian follicles in vitro (17,18) and are capable of promoting oocyte maturation (3,19); however, our studies provide a detailed analysis of their potency relative to progesterone and of their concentrations in the serum and ovaries of living frogs. Surprisingly, we found that progesterone was rapidly converted to AD by isolated oocytes (Fig.…”

Section: Discussionsupporting

confidence: 93%

“…T he phenomenon of progesterone-induced maturation of Xenopus oocytes has served as an in vitro experimental model for studying meiosis and cell cycle regulation for over 30 years (1)(2)(3), with recent work implicating the classical nuclear͞cytoplasmic progesterone receptor (PR) as the mediator of these processes (4,5). Although progesterone is a potent promoter of Xenopus oocyte maturation in vitro, little is known about its role in mediating maturation in vivo.…”

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confidence: 99%

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Evidence that androgens are the primary steroids produced by Xenopus laevis ovaries and may signal through the classical androgen receptor to promote oocyte maturation

Lutz

Cole

Gupta

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

156

142

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Steroid-induced maturation of Xenopus oocytes has long served as a model for studying meiosis. Progesterone has been considered the relevant steroid controlling maturation, perhaps through interactions with classical progesterone receptors. In this study, we provide evidence that androgens, rather than progesterone, are the physiologic mediators of Xenopus oocyte maturation. Androgens were equal or more potent activators of maturation in vitro relative to progesterone and were significantly more abundant in the serum and ovaries of ␤-human chorionic growth hormone-stimulated frogs. Androgen action appeared to be mediated by classical androgen receptors (ARs) expressed in oocytes, as androgen-induced maturation and signaling was specifically attenuated by AR antagonists. Interestingly, we found that progesterone was rapidly converted to the androgen androstenedione in isolated oocytes by the enzyme CYP17, suggesting that androgens may be promoting maturation even under conditions typical for ''progesterone-mediated'' maturation assays. Androgens are thought to play an important role in ovarian development as well as pathology, and signaling through the AR may prove to be a major regulatory mechanism mediating these processes.T he phenomenon of progesterone-induced maturation of Xenopus oocytes has served as an in vitro experimental model for studying meiosis and cell cycle regulation for over 30 years (1-3), with recent work implicating the classical nuclear͞cytoplasmic progesterone receptor (PR) as the mediator of these processes (4, 5). Although progesterone is a potent promoter of Xenopus oocyte maturation in vitro, little is known about its role in mediating maturation in vivo. In other animals, progesterone does not appear to be the primary physiologic mediator of oocyte maturation. For example, oocyte maturation in fish is mediated by the progesterone metabolite 17␣, 20␤-dihydroxyprogesterone (6). In mice, ovaries from females lacking the PR gene still contain well-developed follicles with mature oocytes (7), suggesting that progesterone and its receptor are not necessary for oocyte maturation and that other factors are therefore important. Finally, mifepristone (RU486), a potent inhibitor of both mammalian and Xenopus PR-mediated transcription, does not block progesterone-mediated maturation (5), implying that, even in vitro, signaling via the PR may not be the only mechanism behind progesterone-induced maturation.In an effort to clarify the physiologic importance of progesterone in Xenopus oocyte maturation, we measured the serum and ovarian steroid content of female frogs injected with ␤-human chronic growth hormone (␤-hCG). We show that progesterone is barely detectable in the serum and ovaries of these animals but that androgen concentrations are Ͼ10 times higher than that of progesterone. Further, we demonstrate that oocytes are equally or more sensitive to signaling by androstenedione (AD) and testosterone than progesterone. We identify classical Xenopus androgen receptors (ARs) in oocytes and show t...

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Section: Discussionsupporting

confidence: 93%

mentioning

confidence: 99%

Evidence that androgens are the primary steroids produced by Xenopus laevis ovaries and may signal through the classical androgen receptor to promote oocyte maturation

Lutz

Cole

Gupta

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

156

142

View full text Add to dashboard Cite

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“…Paul Nurse, studying the cell division cycle in yeast, identified genes exerting cell size control at nuclear division [25]. Biochemical investigations carried out on amphibian oocytes a few years earlier [26,27] led to the identification of MPF, or maturation-promoting factor, a factor that was shown to facilitate entry into mitosis and meiosis. In 1988, working with Xenopus oocytes, Lohka and co-workers successfully purified…”

Section: Cyclin-dependent Kinasementioning

confidence: 99%

Protein kinases controlling the onset of mitosis

Ferrari

2006

Cell. Mol. Life Sci.

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Abstract. This review article focuses on protein kinases regulating the onset and transition through mitosis. The essay begins by introducing the structural features of the protein kinase catalytic domain and emphasizing the mechanism of enzymatic activation of this class of proteins. Next follows a short historical perspective on cell division and a description of our current understanding of mitosis. In the central part of the review I examine the four major kinases that set the stage for mitosis, which

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“…Moreover, CAK requires nuclear translocation, that is achieved through the nuclear localization signal contained in cdk7, for generation of its activity (Labbé et al, 1994). This implies that formation of the cytoplasmic store of pre-MPF in prophase-blocked oocytes occurs through a complex intracellular targeting of cdc2 and cyclin B, which have to enter the nucleus to get phosphorylated on Thr 161, to reach the endoplasmic reticulum/Golgi membranes to undergo phosphorylation on Thr 14 by myt1 kinase (Liu et al, 1997;Mueller et al, 1995b), to be phosphorylated on Tyr 15 by wee1 kinase in a soluble compartment (Mueller et al, 1995a), and finally to accumulate in the cytoplasm (Masui and Markert, 1971;Smith and Ecker, 1971)! Moreover, in contrast to a nuclear location of CAK is the observation that microinjection of cyclin A or B in enucleated oocytes leads to the formation of active cyclin-cdc2 complexes, which have been phosphorylated on Thr 161 by some CAK.…”

Section: Cyclin Hmentioning

confidence: 99%

On cyclins, oocytes, and eggs

1997

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Oocyte and egg are suitable model systems for studying cell division since meiotic maturation resembles a G2/M transition and early embryonic divisions are precisely timed and occur without zygotic transcription. The analysis of oocytes and eggs from different species provides the opportunity to understand the roles of proteins that are critical to the progression and maintenance of the cell cycle. Among them, cyclins are certainly worthy of investigation. Mitotic cyclins (cyclins A and B) are clearly implicated in meiosis and early embryonic cell cycles. More recent studies have revealed that G1‐type cyclins (cyclins E and D) could also play a role in both processes and cyclin H has been suggested to participate to CAK activity (cdc2‐activating kinase) in oocytes. The study of cyclins in oocytes and eggs clearly offer insights into their roles during the cell cycle. Mol. Reprod. Dev. 48:397–411, 1997. © 1997 Wiley‐Liss, Inc.

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The interaction of steroids with Rana pipiens oocytes in the induction of maturation

Cited by 382 publications

References 16 publications

Evidence that androgens are the primary steroids produced by Xenopus laevis ovaries and may signal through the classical androgen receptor to promote oocyte maturation

Evidence that androgens are the primary steroids produced by Xenopus laevis ovaries and may signal through the classical androgen receptor to promote oocyte maturation

Protein kinases controlling the onset of mitosis

On cyclins, oocytes, and eggs

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