Evidence for a role of the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase in thapsigargin and Bcl-2 induced changes in Xenopus laevis oocyte maturation

Microinjection of transforming p21 ras protein induces maturation of Xenopus laevis oocytes, and the induction is blocked by coinjection of monoclonal antibody (Y13-259) against p21 ras proteins. Similar to other inducing agents, the effect of p21 ras protein is mediated via the appearance of maturation or meiosis-promoting factor activity. In addition, the neutralizing antibody markedly reduces oocyte maturation after insulin induction, whereas it fails to inhibit progesterone induction. Our results suggest that insulin induces maturation of oocytes via a different pathway than that of steroidal agents. The induction by insulin is ras dependent, and the action of ras may be directed at the steps before meiosis-promoting factor autocatalytic activation. These results suggest a role of p21 ras protein in the events associated with amphibian oocyte maturation.

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Insulin induction of Xenopus laevis oocyte maturation is inhibited by monoclonal antibody against p21 ras proteins

Molecular and Cellular Biology ◽

10.1128/mcb.7.3.1285-1288.1987 ◽

1987 ◽

Vol 7 (3) ◽

pp. 1285-1288

Author(s):

A K Deshpande ◽

H F Kung

Keyword(s):

Monoclonal Antibody ◽

Xenopus Laevis ◽

Oocyte Maturation ◽

Neutralizing Antibody ◽

Xenopus Laevis Oocytes ◽

Xenopus Laevis Oocyte ◽

Ras Proteins ◽

Ras Protein ◽

P21 Ras

Microinjection of transforming p21 ras protein induces maturation of Xenopus laevis oocytes, and the induction is blocked by coinjection of monoclonal antibody (Y13-259) against p21 ras proteins. Similar to other inducing agents, the effect of p21 ras protein is mediated via the appearance of maturation or meiosis-promoting factor activity. In addition, the neutralizing antibody markedly reduces oocyte maturation after insulin induction, whereas it fails to inhibit progesterone induction. Our results suggest that insulin induces maturation of oocytes via a different pathway than that of steroidal agents. The induction by insulin is ras dependent, and the action of ras may be directed at the steps before meiosis-promoting factor autocatalytic activation. These results suggest a role of p21 ras protein in the events associated with amphibian oocyte maturation.

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Environmentally induced changes in mitochondria and endoplasmic reticulum of Saccharomyces carlsbergensis yeast.

The Journal of Cell Biology ◽

10.1083/jcb.71.1.123 ◽

1976 ◽

Vol 71 (1) ◽

pp. 123-135 ◽

Cited By ~ 25

Author(s):

C H Damsky

Keyword(s):

Endoplasmic Reticulum ◽

Surface Density ◽

Volume Density ◽

Sharp Reduction ◽

Inner Mitochondrial Membrane ◽

Large Fluctuations ◽

Mitochondrial Volume ◽

Culture Environment ◽

Induced Changes

The effects of culture environment on the volume density and surface density of mitochondria and endoplasmic reticulum in a facultative yeast were studied. When compared with cells grown aerobically on a nonrepressive substrate, cells grown in the absence of oxygen showed a sharp reduction in both volume density of mitochondria and surface density of the inner mitochondrial membrane (imm) in the remaining mitochondrial profiles. Use of fermentable (repressive) substrates under aerobic conditions restricted the volume density of mitochondria to a much greater extent than the surface density of imm. The range of mitochondrial volume densities in these experiments was 4-11%. Surface density of endoplasmic reticulum (ER) was sensitive to growth rate and in particular to changes in oxygen tension, showing large fluctuations during both anaerobic and aerobic adaptation. These fluctuations in ER are discussed in relation to the known role of this organelle in lipid metabolism.

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Role of zinc in the control of oocyte maturation in Xenopus laevis

Biomedical Research ◽

10.2220/biomedres.21.165 ◽

2000 ◽

Vol 21 (3) ◽

pp. 165-168 ◽

Cited By ~ 1

Author(s):

KEN-ICHI WATANABE ◽

TOSHINOBU TOKUMOTO ◽

KATSUTOSHI ISHIKAWA

Keyword(s):

Xenopus Laevis ◽

Oocyte Maturation

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Embryonic Poly(A)-Binding Protein Stimulates Translation in Germ Cells

Molecular and Cellular Biology ◽

10.1128/mcb.25.5.2060-2071.2005 ◽

2005 ◽

Vol 25 (5) ◽

pp. 2060-2071 ◽

Cited By ~ 43

Author(s):

Gavin S. Wilkie ◽

Philippe Gautier ◽

Diane Lawson ◽

Nicola K. Gray

Keyword(s):

Xenopus Laevis ◽

Oocyte Maturation ◽

Germ Cells ◽

Binding Protein ◽

Expression Patterns ◽

General Role ◽

Early Embryos ◽

Relative Divergence

ABSTRACT The function of poly(A)-binding protein 1 (PABP1) in poly(A)-mediated translation has been extensively characterized. Recently, Xenopus laevis oocytes and early embryos were shown to contain a novel poly(A)-binding protein, ePABP, which has not been described in other organisms. ePABP was identified as a protein that binds AU-rich sequences and prevents shortening of poly(A) tails. Here, we show that ePABP is also expressed in X. laevis testis, suggesting a more general role for ePABP in gametogenesis. We find that ePABP is conserved throughout vertebrates and that mouse and X. laevis cells have similar tissue-specific ePABP expression patterns. Furthermore, we directly assess the role of ePABP in translation. We show that ePABP is associated with polysomes and can activate the translation of reporter mRNAs in vivo. Despite its relative divergence from PABP1, we find that ePABP has similar functional domains and can bind to several PABP1 partners, suggesting that they may use similar mechanisms to activate translation. In addition, we find that PABP1 and ePABP can interact, suggesting that these proteins may be bound simultaneously to the same mRNA. Finally, we show that the activity of both PABP1 and ePABP increases during oocyte maturation, when many mRNAs undergo polyadenylation.

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Identification of cyk, a Cyclin B2 Kinase, as a Novel Calcium/Calmodulin-Dependent Protein Kinase II and Its Role during Xenopus laevis Oocyte Maturation

Experimental Cell Research ◽

10.1006/excr.1999.4637 ◽

1999 ◽

Vol 252 (2) ◽

pp. 303-318 ◽

Cited By ~ 6

Author(s):

I Stevens

Keyword(s):

Protein Kinase ◽

Xenopus Laevis ◽

Oocyte Maturation ◽

Xenopus Laevis Oocyte ◽

Dependent Protein Kinase ◽

Calcium Calmodulin Dependent ◽

Protein Kinase Ii ◽

Dependent Protein

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Cyclin B/p34cdc2 Triggers Phosphorylation of DNA Ligase I During Xenopus laevis Oocyte Maturation

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1995.tb20587.x ◽

1995 ◽

Vol 230 (2) ◽

pp. 491-497 ◽

Cited By ~ 3

Author(s):

Said Aoufouchi ◽

Claude Prigent ◽

Chris Ford ◽

Pierre Thiebaud ◽

Michel Philippe ◽

...

Keyword(s):

Xenopus Laevis ◽

Oocyte Maturation ◽

Cyclin B ◽

Dna Ligase ◽

Xenopus Laevis Oocyte ◽

Dna Ligase I

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Testosterone and Progesterone Rapidly Attenuate Plasma Membrane Gβγ-Mediated Signaling in Xenopus laevis Oocytes by Signaling through Classical Steroid Receptors

Molecular Endocrinology ◽

10.1210/me.2006-0301 ◽

2007 ◽

Vol 21 (1) ◽

pp. 186-196 ◽

Cited By ~ 26

Author(s):

Kristen Evaul ◽

Michelle Jamnongjit ◽

Bala Bhagavath ◽

Stephen R. Hammes

Keyword(s):

Xenopus Laevis ◽

G Protein ◽

G Proteins ◽

Oocyte Maturation ◽

Live Cells ◽

Inhibition Mechanism ◽

Xenopus Laevis Oocytes ◽

Xenopus Laevis Oocyte ◽

Potassium Influx

Abstract Many transcription-independent (nongenomic) steroid effects are regulated by G proteins. A well-established, biologically relevant example of steroid/G protein interplay is steroid-triggered oocyte maturation, or meiotic resumption, in Xenopus laevis. Oocyte maturation is proposed to occur through a release of inhibition mechanism whereby constitutive signaling by Gβγ and other G proteins maintains oocytes in meiotic arrest. Steroids (androgens in vivo, and androgens and progesterone in vitro) overcome this inhibition to promote meiotic resumption. To test this model, we used G protein-regulated inward rectifying potassium channels (GIRKs) as markers of Gβγ activity. Overexpression of GIRKs 1 and 2 in Xenopus oocytes resulted in constitutive potassium influx, corroborating the presence of basal Gβγ signaling in resting oocytes. Testosterone and progesterone rapidly reduced potassium influx, validating that steroids attenuate Gβγ activity. Interestingly, reduction of classical androgen receptor (AR) expression by RNA interference abrogated testosterone’s effects on GIRK activity at low, but not high, steroid concentrations. Accordingly, androgens bound to the Xenopus progesterone receptor (PR) at high concentrations, suggesting that, in addition to the AR, the PR might mediate G protein signaling when androgens levels are elevated. In contrast, progesterone bound with high affinity to both the Xenopus PR and AR, indicating that progesterone might signal and promote maturation through both receptors, regardless of its concentration. In sum, these studies introduce a novel method for detecting nongenomic steroid effects on G proteins in live cells in real time, and demonstrate that cross talk may occur between steroids and their receptors during Xenopus oocyte maturation.

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