Effects of Phosphatidylinositol 3-Kinase Inhibitors, Wortmannin and LY294002, on Germinal Vesicle Breakdown (GVBD) in Porcine Oocytes.

Shimada, M.; Anas, Mohamed-Kheir Idris; Takato, Tsuyoshi

doi:10.1262/jrd.44.281

Cited by 20 publications

(11 citation statements)

References 28 publications

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“…In Xenopus, PKA is thought to phosphorylate some unidentified protein that directly or indirectly suppresses c-mos translation, which is required for the activation of MAP kinase (Matten et al, 1994;Sagata, 1997). In addition, MAP kinase activity in mammalian oocytes is supposed to be affected by phosphatidylinositol 3-kinase (PI-3K) (Shimada et al, 1998;Shimada & Terada, 2002). In our experiments, MAP kinase activity was suppressed at the same time as Cdc2 kinase, when cAMP achieved a maximal level in the oocytes.…”

Section: Discussionmentioning

confidence: 58%

Effect of caffeine on meiotic maturation of porcine oocytes

Kren¹,

Ogushi

Miyano

2004

Zygote

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This study was conducted to evaluate the effect of caffeine on the meiotic maturation of porcine oocytes. Oocyte-cumulus complexes were collected from slaughterhouse-derived ovaries and cultured for 24, 32 or 48 h in medium 199 supplemented with 10% fetal calf serum, 10 µg/ml FSH, 50 µg/ml sodium pyruvate and 50 µg/ml gentamicin in the presence or absence of 2.5 mM caffeine. Caffeine inhibited the meiotic resumption of pig oocytes effectively after 24 h of culture, and 95.5% of oocytes were arrested at the germinal vesicle (GV) stage (control 17.8%, p < 0.05). Prolonged culture with caffeine up to 32 h or 48 h, however, resulted in a significant decrease in the inhibitory effect (GV: 13.8% and 8.2%). The number of oocytes at metaphase II after 48 h of culture in the presence of caffeine was significantly lower than that in the control medium (65.3% vs 94.7%, p < 0.05). The withdrawal of caffeine after 24 h of culture resulted in the resumption of meiotic maturation, and the oocytes reached metaphase II after 48 h. However, the ability of caffeine-treated oocytes to develop to blastocysts after artificial activation was lower than that of the control (5.5% vs 9.1%, p < 0.05). Caffeine treatment significantly increased cAMP levels in the oocytes after 24 h of culture, while both Cdc2 kinase and MAP kinase activation were inhibited in the oocytes. These results suggest that caffeine, similarly to other purine derivatives, prolongs the meiotic arrest of porcine oocytes at the GV stage, perhaps by its action of increasing the cAMP level and by the suppression of Cdc2 kinase and MAP kinase activities in the oocytes.

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Section: Discussionmentioning

confidence: 58%

Effect of caffeine on meiotic maturation of porcine oocytes

Kren¹,

Ogushi

Miyano

2004

Zygote

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“…In our previous study (Shimada et al 1998), the addition of LY294002 to gonadotropin-containing medium interfered with the disappearance of gapjunctional protein connexin-43 in cumulus cells and meiotic resumption of porcine cumulus-enclosed oocytes. The results revealed that PI 3-kinase in cumulus cells also played an important role in gonadotropin-regulation of cell functions.…”

Section: Discussionmentioning

confidence: 80%

Phosphatidylinositol 3-kinase in cumulus cells is responsible for both suppression of spontaneous maturation and induction of gonadotropin-stimulated maturation of porcine oocytes

Shimada¹,

Ito²,

Yamashita³

et al. 2003

Journal of Endocrinology

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In this study, we investigated the mechanisms of protein kinase B (PKB) activation and its role in cumulus cells during in vitro meiotic resumption of porcine oocytes. PKB activity in cumulus cells was significantly decreased by 12 h cultivation of cumulus-oocyte complexes (COCs) in basic medium. However, the addition of phosphodiesterase inhibitors, hypoxanthine or 3-isobutyl-1-methylxanthine, maintained the level of PKB activity in cumulus cells at comparable with that in cumulus cells just after collection from their follicles. When COCs were cultured with phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, LY294002, PKB activity was significantly decreased, and both caspase 3 activity and the proportion of apoptotic cells were significantly increased as compared with those in cumulus cells just after collection from their follicles. Moreover, the inhibitory effect of hypoxanthine on spontaneous meiotic resumption was overcome by addition of LY294002. On the other hand, markedly high activity of PKB and high intensity of the phosphorylated PKB band were observed in cumulus cells of COCs which were cultured with FSH. The addition of 20 µM LY294002 to FSH-containing medium induced an apoptosis of cumulus cells, whereas little apoptotic-positive signal was detected in COCs cultured with 5 µM LY294002 and FSH. However, the inhibitory effects of LY294002 on progesterone production by cumulus cells and germinal vesicle breakdown in oocytes reached a maximum at 5 µM. Thus, high activity of the PI 3-kinase-PKB pathway in cumulus cells plays an important role in FSH regulation of cell function. Judging from these results, it is estimated that PI 3-kinase in cumulus cells is required for both the suppression of spontaneous meiotic resumption and the induction of gonadotropin-stimulated meiotic resumption.

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“…The final concentration of each compound (as describe above) was obtained by dilution (1:1000) with the maturation medium. The final concentrations of dimethylsulfoxide and ethanol were 0.1% (v/v), which did not affect the function of cumulus cells during meiotic resumption of porcine oocytes [23].…”

Section: In Vitro Culture Of Porcine Cocsmentioning

confidence: 99%

Positive Feedback Loop Between Prostaglandin E2 and EGF-Like Factors Is Essential for Sustainable Activation of MAPK3/1 in Cumulus Cells During In Vitro Maturation of Porcine Cumulus Oocyte Complexes1

Yamashita

Okamoto

Kawashima

et al. 2011

Biology of Reproduction

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During in vitro maturation of porcine cumulus-oocyte complexes (COCs), follicle-stimulating hormone (FSH) increases both prostaglandin E2 (PGE2) production and the expression levels of EGF-like factors. The ligands act on cumulus cells by the autocrine system due to their specific receptors, EP2, EP4, or EGF receptor. When each pathway is suppressed by inhibitors, complete cumulus expansion and oocyte maturation do not occur. In this study, we examined the relationship between both of these pathways in cumulus cells of porcine COCs. When COCs were cultured with FSH, Fshr mRNA expression was immediately decreased within 5 h, whereas Ptger2, Ptger4, and Ptgs2 expression levels were significantly increased in cumulus cells in the culture containing FSH for 5 or 10 h. The PTGS2 inhibitor NS398 significantly suppressed not only PGE2 secretion at any culture time point but also Areg, Ereg, and Tace/Adam17 expression in cumulus cells at 10 and 20 h but not at 1 or 5 h. During the early culture period, phosphorylation of MAPK3 and MAPK1 (MAPK3/1) was not affected by NS398; however, at 10 and 20 h, phosphorylation was suppressed by the drug. Furthermore, down-regulations of MAPK3/1 phosphorylation and expression of the target genes by NS398 was overcome by the addition of either PGE2 or EGF. FSH-induced cumulus expansion and meiotic progression to the MII stage were also suppressed by NS398, whereas these effects were also overcome by addition of either PGE2 or EGF. These results indicated that PGE2 is involved in the sustainable activation of MAPK3/1 in cumulus cells via the induction of EGF-like factor, which is required for cumulus expansion and meiotic maturation of porcine COCs.

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Effects of Phosphatidylinositol 3-Kinase Inhibitors, Wortmannin and LY294002, on Germinal Vesicle Breakdown (GVBD) in Porcine Oocytes.

Cited by 20 publications

References 28 publications

Effect of caffeine on meiotic maturation of porcine oocytes

Effect of caffeine on meiotic maturation of porcine oocytes

Phosphatidylinositol 3-kinase in cumulus cells is responsible for both suppression of spontaneous maturation and induction of gonadotropin-stimulated maturation of porcine oocytes

Positive Feedback Loop Between Prostaglandin E2 and EGF-Like Factors Is Essential for Sustainable Activation of MAPK3/1 in Cumulus Cells During In Vitro Maturation of Porcine Cumulus Oocyte Complexes1

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