Histone 1 phosphotransferase activities during the maturation of oocytes of Xenopus laevis

Masaracchia, Ruthann A.; Maller, James L.; Walsh, Donal A.

doi:10.1016/0003-9861(79)90589-7

Cited by 30 publications

(19 citation statements)

References 38 publications

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“…The total amount of PKAc in the oocyte was estimated to be between 50 and 70 ng per oocyte (1.25-1.75 M). No changes in the concentration of PKAc could be detected by immunoblot between G 2 -arrested and mature oocytes, which is in agreement with previous reports (24). …”

Section: Identification and Quantification Of Endogenous Pkac In Xenopussupporting

confidence: 93%

“…3D Middle, lanes 2 and 5) whereas none of the other mutants did. The small amount of PKA-RI detected in immunoblots is consistent with previous reports indicating that PKA holoenzymes of type II are predominant in oocytes (24). Our results demonstrate that the kinase-inactivating mutation K72R interferes with the binding of PKAc to PKA-R subunits.…”

Section: Inhibition Of Progesterone-induced Meiotic Maturation By Xpkacsupporting

confidence: 92%

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Inhibition of Xenopus oocyte meiotic maturation by catalytically inactive protein kinase A

Schmitt

Nebreda

2002

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

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Progesterone induces G2-arrested Xenopus oocytes to develop into fertilizable eggs in a process called meiotic maturation. Protein kinase A (PKA), the cAMP-dependent protein kinase, has long been known to be a potent inhibitor of meiotic maturation, but little information is available on how PKA functions. We have cloned two Xenopus PKA catalytic subunit isoforms, XPKA␣ and XPKA␤. These proteins are 89% identical and both inhibit progesteroneinduced meiotic maturation when overexpressed at low levels, suggesting that PKA activity is tightly regulated in the oocyte. Unexpectedly, catalytically inactive XPKA mutants are able to block progesterone-induced maturation as efficiently as the wild-type active XPKA. These mutants also block meiotic maturation induced by Mos, but are less efficient at inhibiting Cdc25C-induced maturation. Our results indicate that PKA can inhibit meiotic maturation by a novel mechanism, which does not require its kinase activity and is also independent of binding to the PKA regulatory subunits.

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Section: Identification and Quantification Of Endogenous Pkac In Xenopussupporting

confidence: 93%

Section: Inhibition Of Progesterone-induced Meiotic Maturation By Xpkacsupporting

confidence: 92%

Inhibition of Xenopus oocyte meiotic maturation by catalytically inactive protein kinase A

Schmitt

Nebreda

2002

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

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“…The observed modest reduction of oocyte cAMP levels will have a significant effect on PKA activity in intact oocytes, since the basal cAMP concentration in prophase oocytes (1 µM) is close to the apparent activation constant of type II PKA, predominant in frog oocytes. 34,35 Consistently, a complete inactivation of PKA is observed within 30-60 minutes of progesterone treatment. 36 The injection of the regulatory subunit of PKA (PKAr) or of a peptide inhibitor (PKI) causes hormone-independent oocyte maturation (Table 1) whereas injection of the catalytic subunit PKAc prevents progesterone-induced oocyte maturation.…”

Section: Pka a Key Enzyme In The Control Of Prophase Arrestsupporting

confidence: 58%

Oocyte Maturation, Mos and Cyclins—A Matter of Synthesis: Two Functionally Redundant Ways to Induce Meiotic Maturation

Haccard

Jessus²

2006

Cell Cycle

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The development of an immature oocyte into a fertilizable gamete is a process known as meiotic maturation. In vertebrates, it corresponds to the transition from the prophase arrest of the first meiotic division (usually considered as a late G 2 phase) to the metaphase arrest of the second meiotic division. This transition is controlled by modulating the activity of the cyclin B-Cdc2 complex, MPF (M-phase promoting factor), the universal regulator of the G 2 /M transition. Meiotic maturation of frog oocytes is triggered by steroid hormones through a rapid, necessary and sufficient suppression of PKA and requires ongoing protein synthesis. A long-standing question has been to identify key protein(s) required to trigger the activation of MPF in response to the hormonal signal. Here we will discuss data supporting the view that steroids bring about meiotic maturation through functionally redundant pathways involving synthesis of Mos or of cyclin proteins, reinforcing the robustness of the system.

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“…The level of impaired inhibition was greater for R133A/K72H PKAc (Fig. 5B), perhaps reflecting a greater abundance of RII over RI, as suggested by early biochemical studies (30).…”

Section: Fig 4 Effect Of Regulatory Subunit Interaction On Inhibitimentioning

confidence: 60%

Regulation of the G2/M Transition in Xenopus Oocytes by the cAMP-dependent Protein Kinase

Eyers

Liu

Hayashi

et al. 2005

Journal of Biological Chemistry

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Vertebrate oocytes are arrested in G 2 phase of the cell cycle at the prophase border of meiosis I. Progesterone treatment of Xenopus oocytes releases the G 2 block and promotes entry into the M phases of meiosis I and II. Substantial evidence indicates that the release of the G 2 arrest requires a decrease in cAMP and reduced activity of the cAMP-dependent protein kinase (PKAc). It has been reported and we confirm here that microinjection of either wild type or kinase-dead K72R PKAc inhibits progesterone-dependent release of the G 2 arrest with equal potency and that inhibition can be reversed by a second injection of the heat-stable inhibitor of PKAc, PKI. However, a mutant enzyme predicted to be completely kinase-dead from the crystal structure of PKAc, K72H PKAc, was much less inhibitory when carrying additional mutations that block interaction with either type I or type II regulatory subunit. Moreover, inhibition by K72H PKAc was reversed by PKI at a 30-fold lower concentration and with more rapid kinetics compared with wild type PKAc. K72R PKAc was found to have low but detectable activity after incubation in an oocyte extract. These results indicate that inhibition of the progesterone-dependent G 2 /M transition in oocytes after microinjection of dead PKAc reflects either low residual activity or binding to regulatory subunits with a resulting net increase in the level of endogenous wild type PKAc. Consistent with this hypothesis, the induction of mitosis in Xenopus egg extracts by the addition of cyclin B was blocked by wild type PKAc but not by K72H PKAc. The identification of substrates for PKAc that maintain cell cycle arrest in G 2 remains an important goal for future work.

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Histone 1 phosphotransferase activities during the maturation of oocytes of Xenopus laevis

Cited by 30 publications

References 38 publications

Inhibition of Xenopus oocyte meiotic maturation by catalytically inactive protein kinase A

Inhibition of Xenopus oocyte meiotic maturation by catalytically inactive protein kinase A

Oocyte Maturation, Mos and Cyclins—A Matter of Synthesis: Two Functionally Redundant Ways to Induce Meiotic Maturation

Regulation of the G2/M Transition in Xenopus Oocytes by the cAMP-dependent Protein Kinase

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