Dynamics of meiosis and protein kinase activities in bovine oocytes correlated to prolactin treatment and follicle size

Torner, H.; Kubelka, Michal; Heleil, B.; Tomek, Wolfgang; Alm, H.; Kuzmina, T. I.; Guiard, V.

doi:10.1016/s0093-691x(01)00451-4

Cited by 28 publications

(26 citation statements)

References 33 publications

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“…After 10 or 24 h of IVM the majority of oocytes had reached M I and M II respectively. These observations are in accordance with results from Torner et al (2001). For this purpose, oocytes derived at these time points were used for further biochemical investigations.…”

Section: Analysis Of Akt Abundance Phosphorylation and Activity Durisupporting

confidence: 88%

“…The COCs collected were matured according to the method of Torner et al (2001) in TCM 199, supplemented with 3 mg/ml bovine serum albumin (BSA), covered with a layer of mineral oil, at 38.5 8C, 5% CO 2 and saturated humidity for different time intervals (0, 10 and 24 h). The IVM was performed in four-well dishes with 50 COCs in 500 ml medium.…”

Section: Source and Collection Of Oocytesmentioning

confidence: 99%

“…Then the oocytes were evaluated for the stage of meiosis by staining with aceto-orcein, or used for biochemical analysis. The analysis of samples was carried out in welldefined time periods (Torner et al 2001) of 0, 10 and 24 h of IVM (GV, M I and M II stages) respectively.…”

Section: Source and Collection Of Oocytesmentioning

confidence: 99%

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Activation of Akt (protein kinase B) stimulates metaphase I to metaphase II transition in bovine oocytes

Tomek¹,

Smiljaković²

2005

Reproduction

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In somatic cells, the serine/threonine kinase Akt (or protein kinase B) was shown to contribute to processes linked to cellular growth, cell survival and cell cycle regulation. In contrast to these findings, the function of Akt during the meiosis of mammalian oocytes remains to be investigated. We analysed the phosphorylation pattern and the activity of Akt during meiotic maturation (transition from prophase I to metaphase II) of bovine oocytes. The oocytes were matured in vitro (IVM) for 0, 10 and 24 h to reach the germinal vesicle (GV), metaphase I (M I) and metaphase II (M II) stages respectively. The abundance and phosphorylation pattern of Akt was revealed by Western blotting using total Akt or phosphoso-Akt-specific antibodies. The activity of this particular kinase was determined by an in vitro kinase assay. Furthermore, functional properties were analysed by cultivating oocytes in the presence of the Akt inhibitor SH6. The results showed that the overall abundance of Akt did not change significantly during IVM. On the other hand, Akt became phosphorylated at Thr 308 and Ser 473, reaching its maximum at the M I phase. In the GV and M II stages, only low basal phosphorylation levels were observed on both sides. This phosphorylation profile corresponded strictly to the activity of the kinase. The cultivation of oocytes in the presence of the phosphatidylinositol analogue SH6 for 24 h showed that, with higher concentrations, up to 65% of the oocytes were arrested in the M I stage. This result indicated that Akt is involved in the M I/M II transition during the meiotic maturation of bovine oocytes. The physiological aspects of the Akt function will be discussed.

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Section: Analysis Of Akt Abundance Phosphorylation and Activity Durisupporting

confidence: 88%

Section: Source and Collection Of Oocytesmentioning

confidence: 99%

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Activation of Akt (protein kinase B) stimulates metaphase I to metaphase II transition in bovine oocytes

Tomek¹,

Smiljaković²

2005

Reproduction

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“…Here we looked for a correlation between the kinetics of maturation and the follicle sizes but no significant difference was demonstrated at any of the meiotic stages and progression through meiosis respects the timing described by others [41,42]. However, a recent study [43] demonstrated that oocytes from 4 to 5 mm follicles required slightly more time to reach anaphase I than those from 2 to 3 mm follicles. Maybe differences in the quality of the COC could explain this discrepancy as quality influences progression though meiosis.…”

Section: Discussionmentioning

confidence: 86%

Influence of antral follicle size on oocyte characteristics and embryo development in the bovine

et al. 2005

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The developmental competence of bovine oocytes isolated from antral follicles of different sizes was assessed in three European laboratories (Belgium, UCL; Denmark, DIAS; France, INRA). Using the same protocol for in vitro production of embryos, the oocytes isolated from follicles with a diameter !6 mm always gave a higher blastocyst rate than oocytes from follicles <4 mm (UCL: 42% versus 14%, DIAS: 50% versus 35%, INRA: 39% versus 22%; P < 0.05). Blastocyst cell number was not affected by follicle size. Several parameters were investigated for these oocytes. The energy metabolism of cumulus-oocyte-complexes and of denuded oocytes was assessed by the oxygen and pyruvate uptake and by lactate release both at the beginning and the end of the maturation. No effect of follicle size could be detected but lactate release increased after maturation. The global profile of transcripts, the pattern of protein neosynthesis and the kinetics of meiosis resumption were not affected by follicle size. The developmental kinetics of derived embryos was also analysed. Whatever the follicle size, viable embryos had a shorter first and third embryonic cell cycle. Among the viable embryos, the size of the follicle interfered with the fourth cell cycle duration. A higher percentage of blastocysts issued from large follicle presented a short fourth cell cycle (9 h) (35% versus 6%; P < 0.05). Beside, blastocysts derived from small follicles had a delayed cavitation and expansion. Thereby, a higher developmental competence for oocytes from follicle !6 mm versus <4 mm was Theriogenology 63 (2005) [841][842][843][844][845][846][847][848][849][850][851][852][853][854][855][856][857][858][859]

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“…Cdc2 can phosphorylate histone H1, at least in vitro [29,30], and it also acts as a lamin kinase [31], which suggests its role in nuclear membrane disintegration. Its activation in bovine oocytes can be prevented by culturing the oocytes in the presence of butyrolactone I (BL I).…”

Section: Introductionmentioning

confidence: 99%

Regulation of Translation During In Vitro Maturation of Bovine Oocytes: The Role of MAP Kinase, eIF4E (Cap Binding Protein) Phosphorylation, and eIF4E-BP11

Tomek

Sterza²,

Kubelka

et al. 2002

Biology of Reproduction

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Meiotic maturation of mammalian oocytes (transition from prophase I to metaphase II) is accompanied by complex changes in the protein phosphorylation pattern. At least two major protein kinases are involved in these events; namely, cdc2 kinase and mitogen-activated protein (MAP) kinase, because the inhibition of these kinases arrest mammalian oocytes in the germinal vesicle (GV) stage. We show that during meiotic maturation of bovine oocytes, the translation initiation factor, eIF4E (the cap binding protein), gradually becomes phosphorylated. This substantial phosphorylation begins at the time of germinal vesicle breakdown (GVBD) and continues to the metaphase II stage. The onset of eIF4E phosphorylation occurs in parallel with a significant increase in overall protein synthesis. However, although eIF4E is nearly fully phosphorylated in metaphase II oocytes, protein synthesis reaches only basal levels at this stage, similar to that of prophase I oocytes, in which the factor remains unphosphorylated. We present evidence that a specific repressor of eIF4E, the binding protein 4E-BP1, is present and could be involved in preventing eIF4E function in metaphase II stage oocytes. Recently, two protein kinases, called Mnk1 and Mnk2, have been identified in somatic cells as eIF4E kinases, both of which are substrates of MAP kinase in vivo. In bovine oocytes, a specific inhibitor of cdk kinases, butyrolactone I, arrests oocytes in GV stage and prevents activation of both cdc2 and MAP kinase. Under these conditions, the phosphorylation of eIF4E is also blocked, and its function in initiation of translation is impaired. In contrast, PD 098059, a specific inhibitor of the MAP kinase activation pathway, which inhibits the MAP kinase kinase, called MEK function, leads only to a postponed GVBD, and a delay in MAP kinase and eIF4E phosphorylation. These results indicate that in bovine oocytes, 1) MAP kinase activation is only partially dependent on MEK kinase, 2) MAP kinase is involved in eIF4E phosphorylation, and 3) the abundance of fully phosphorylated eIF4E does not necessarily directly stimulate protein synthesis. A possible MEK kinase-independent pathway of MAP kinase phosphorylation and the role of 4E-BP1 in repressing translation in metaphase II oocytes are discussed.

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Dynamics of meiosis and protein kinase activities in bovine oocytes correlated to prolactin treatment and follicle size

Cited by 28 publications

References 33 publications

Activation of Akt (protein kinase B) stimulates metaphase I to metaphase II transition in bovine oocytes

Activation of Akt (protein kinase B) stimulates metaphase I to metaphase II transition in bovine oocytes

Influence of antral follicle size on oocyte characteristics and embryo development in the bovine

Regulation of Translation During In Vitro Maturation of Bovine Oocytes: The Role of MAP Kinase, eIF4E (Cap Binding Protein) Phosphorylation, and eIF4E-BP11

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