The Mos/MAPK pathway is involved in metaphase II arrest as a cytostatic factor but is neither necessary nor sufficient for initiating oocyte maturation in goldfish

2000 ◽  
Vol 210 (8-9) ◽  
pp. 416-425 ◽  
Author(s):  
Hiroko Kajiura-Kobayashi ◽  
Noriyuki Yoshida ◽  
Noriyuki Sagata ◽  
M. Yamashita ◽  
Yoshitaka Nagahama
Keyword(s):  
Oocyte Maturation ◽  
Mapk Pathway ◽  
Cytostatic Factor

scholarly journals Regulation of Raf-1-dependent signaling during early Xenopus development.

1995 ◽  
Vol 15 (12) ◽  
pp. 6686-6693 ◽  
Author(s):  
A M MacNicol ◽  
A J Muslin ◽  
E L Howard ◽  
A Kikuchi ◽  
M C MacNicol ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Embryonic Cell ◽  
Cycle Progression ◽  
Mapk Activity ◽  
Cytostatic Factor ◽  
Differentiation And Proliferation

The Raf-1 gene product is activated in response to cellular stimulation by a variety of growth factors and hormones. Raf-1 activity has been implicated in both cellular differentiation and proliferation. We have examined the regulation of the Raf-1/MEK/MAP kinase (MAPK) pathway during embryonic development in the frog Xenopus laevis. We report that Raf-1, MEK, and MAPK activities are turned off following fertilization and remain undetectable up until blastula stages (stage 8), some 4 h later. Tight regulation of the Raf-1/MEK/MAPK pathway following fertilization is crucial for embryonic cell cycle progression. Inappropriate reactivation of MAPK activity by microinjection of oncogenic Raf-1 RNA results in metaphase cell cycle arrest and, consequently, embryonic lethality. Our findings demonstrate an absolute requirement, in vivo, for inactivation of the MAPK signaling pathway to allow normal cell cycle progression during the period of synchronous cell divisions which occur following fertilization. Further, we show that cytostatic factor effects are mediated through MEK and MAPK.

scholarly journals The casein kinase II beta subunit binds to Mos and inhibits Mos activity.

1997 ◽  
Vol 17 (4) ◽  
pp. 1904-1912 ◽  
Author(s):  
M Chen ◽  
D Li ◽  
E G Krebs ◽  
J A Cooper
Keyword(s):  
Oocyte Maturation ◽  
Mapk Pathway ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Beta Subunit ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Assay ◽  
Meiotic Maturation ◽  
Mapk Activation ◽  
C Terminus

Mos is a germ cell-specific serine/threonine kinase and is required for Xenopus oocyte maturation. Active Mos stimulates a mitogen-activated protein kinase (MAPK) by directly phosphorylating and activating MAPK kinase (MKK). We report here that the Xenopus homolog of the beta subunit of casein kinase II (CKII beta) binds to and regulates Mos. The Mos-interacting region of CKII beta was mapped to the C terminus. Mos bound to CKII beta in somatic cells ectopically expressing Mos and CKII beta as well as in unfertilized Xenopus eggs. CKII beta inhibited Mos-mediated MAPK activation in rabbit reticulocyte lysates and repressed MKK activation by v-Mos in a coupled kinase assay. In addition, microinjection of CKII beta mRNA into Xenopus oocytes inhibited progesterone-induced meiotic maturation and MAPK activation, presumably by binding of CKII beta to Mos and thereby inhibiting MAPK activation. Moreover, this inhibitory phenotype could be rescued by another protein that binds to CKII beta, CKII alpha. The ability of ectopic CKII beta to inhibit meiotic maturation and the detection of a complex between endogenous Mos and CKII beta suggest that CKII beta may act as an inhibitor of Mos during oocyte maturation, perhaps setting a threshold beyond which Mos protein must accumulate before it can activate the MAPK pathway.

scholarly journals Involvement of Mos–MEK–MAPK pathway in cytostatic factor (CSF) arrest in eggs of the parthenogenetic insect, Athalia rosae

2008 ◽  
Vol 125 (11-12) ◽  
pp. 996-1008 ◽  
Author(s):  
Daisuke S. Yamamoto ◽  
Kazunori Tachibana ◽  
Megumi Sumitani ◽  
Jae Min Lee ◽  
Masatsugu Hatakeyama
Keyword(s):  
Mapk Pathway ◽  
Athalia Rosae ◽  
Cytostatic Factor

scholarly journals Meiotic spindle stability depends on MAPK-interacting and spindle-stabilizing protein (MISS), a new MAPK substrate

2002 ◽  
Vol 157 (4) ◽  
pp. 603-613 ◽  
Author(s):  
Christophe Lefebvre ◽  
M. Emilie Terret ◽  
Alexandre Djiane ◽  
Pascale Rassinier ◽  
Bernard Maro ◽  
...  
Keyword(s):  
Antisense Rna ◽  
Mapk Pathway ◽  
Meiotic Spindle ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein ◽  
Cytostatic Factor ◽  
Morpholino Oligonucleotides ◽  
Spindle Stability ◽  
Two Hybrid ◽  
Segregation Of Chromosomes

Vertebrate oocytes arrest in the second metaphase of meiosis (metaphase II [MII]) by an activity called cytostatic factor (CSF), with aligned chromosomes and stable spindles. Segregation of chromosomes occurs after fertilization. The Mos/…/MAPK (mitogen-activated protein kinases) pathway mediates this MII arrest. Using a two-hybrid screen, we identified a new MAPK partner from a mouse oocyte cDNA library. This protein is unstable during the first meiotic division and accumulates only in MII, where it localizes to the spindle. It is a substrate of the Mos/…/MAPK pathway. The depletion of endogenous RNA coding for this protein by three different means (antisense RNA, double-stranded [ds] RNA, or morpholino oligonucleotides) induces severe spindle defects specific to MII oocytes. Overexpressing the protein from an RNA not targeted by the morpholino rescues spindle destabilization. However, dsRNA has no effect on the first two mitotic divisions. We therefore have discovered a new MAPK substrate involved in maintaining spindle integrity during the CSF arrest of mouse oocytes, called MISS (for MAP kinase–interacting and spindle-stabilizing protein).

scholarly journals Graded Mitogen-Activated Protein Kinase Activity Precedes Switch-Like c-Fos Induction in Mammalian Cells

2005 ◽  
Vol 25 (11) ◽  
pp. 4676-4682 ◽  
Author(s):  
Jeffrey P. MacKeigan ◽  
Leon O. Murphy ◽  
Christopher A. Dimitri ◽  
John Blenis
Keyword(s):  
Protein Kinase ◽  
Cell Fate ◽  
Oocyte Maturation ◽  
Mammalian Cells ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Cell Fate Decisions ◽  
Graded Response ◽  
Mitogen Activated Protein

ABSTRACT The mitogen-activated protein kinase (MAPK) pathway is an evolutionarily conserved signaling module that controls important cell fate decisions in a variety of physiological contexts. During Xenopus oocyte maturation, the MAPK cascade converts an increasing progesterone stimulus into a switch-like, all-or-nothing response. While the importance of such switch-like behavior is widely discussed in the literature, it is not known whether the MAPK pathway in mammalian cells exhibits a switch-like or graded response. For this study, we used flow cytometry and immunofluorescence to generate single-cell measurements of MAPK signaling in Swiss 3T3 fibroblasts. In contrast to the case in Xenopus oocytes, we found that ERK activation in individual mammalian cells is not ultrasensitive and shows a graded response to changes in agonist concentration. Thus, the conserved MAPK signaling module exhibits different systems-level properties in different cellular contexts. Furthermore, the graded ERK response was converted into a more switch-like behavior at the level of immediate-early gene induction and cell cycle progression. Thus, while MAPK signaling is involved in all-or-nothing cell fate decisions for both Xenopus oocyte maturation and mammalian fibroblast proliferation, the underlying mechanisms responsible for the switch-like nature of the cellular responses are different in these two systems, with the mechanism appearing to lie downstream of the kinase cascade in mammalian fibroblasts.

scholarly journals Phosphorylation of conserved serine residues does not regulate the ability of mosxe protein kinase to induce oocyte maturation or function as cytostatic factor.

1992 ◽  
Vol 116 (3) ◽  
pp. 725-735 ◽  
Author(s):  
R S Freeman ◽  
A N Meyer ◽  
J Li ◽  
D J Donoghue
Keyword(s):  
Protein Kinase ◽  
Oocyte Maturation ◽  
Xenopus Oocytes ◽  
Peptide Mapping ◽  
Biological Activities ◽  
Phosphorylation Site ◽  
Site Directed Mutagenesis ◽  
Wild Type ◽  
Regulatory Phosphorylation ◽  
Cytostatic Factor

Expression of the mosxe protein kinase is required for the normal meiotic maturation of Xenopus oocytes and overexpression induces maturation in the absence of other stimuli. In addition, mosxe functions as a component of cytostatic factor (CSF), an activity responsible for arrest of the mature egg at metaphase II. After microinjection of Xenopus oocytes with in vitro synthesized RNA encoding either wild-type mosxe or kinase-inactive mosxe(R90), both proteins are phosphorylated exclusively on serine residues and exhibit essentially identical chymotryptic maps. Since the phosphorylated kinase-inactive mosxe(R90) protein was recovered from resting oocytes that have not yet begun to translate endogenous mosxe, this indicates that the major phosphopeptides of mosxe(R90) are phosphorylated by a preexisting protein kinase present in resting oocytes, and are not the result of autophosphorylation. The results presented here also indicate that the mosxe protein does not undergo significant phosphorylation at unique sites during oocyte maturation. If the biological activity of mosxe were regulated by phosphorylation, a site of regulatory phosphorylation would most likely be conserved among mos proteins of different species. Site-directed mutagenesis was used to construct 13 individual serine----alanine mutations at conserved residues (3, 16, 18, 25, 26, 57, 71, 76, 102, 105, 127, 211, and 258). These 13 mutants were analyzed for their abilities to induce oocyte maturation and to function as CSF. Results obtained with the mosxe(A105) mutant revealed that serine-105 is required for both maturation induction and CSF activity, even though serine-105 does not represent a major site of phosphorylation. All of the remaining serine----alanine mosxe mutants induced oocyte maturation and exhibited CSF activity comparable with the wild type. These results demonstrate that none of the conserved serines examined in this study function as regulatory phosphorylation sites for these biological activities. Peptide mapping of the remaining mosxe mutants identified serine-3 as a major phosphorylation site in vivo, which is contained within the chymotryptic peptide MPSPIPVERF.

A new role for Mos in Xenopus oocyte maturation: targeting Myt1 independently of MAPK

Development ◽  
2002 ◽  
Vol 129 (9) ◽  
pp. 2129-2139 ◽  
Author(s):  
Marion Peter ◽  
Jean-Claude Labbé ◽  
Marcel Dorée ◽  
Elisabeth Mandart
Keyword(s):  
Protein Kinase ◽  
Oocyte Maturation ◽  
Xenopus Oocyte ◽  
Xenopus Oocytes ◽  
Mapk Pathway ◽  
Germinal Vesicle ◽  
Mapk Cascade ◽  
Germinal Vesicle Breakdown ◽  
Mapk Activation

The resumption of meiosis in Xenopus arrested oocytes is triggered by progesterone, which leads to polyadenylation and translation of Mos mRNA, then activation of MAPK pathway. While Mos protein kinase has been reported to be essential for re-entry into meiosis in Xenopus, arrested oocytes can undergo germinal vesicle breakdown (GVBD) independently of MAPK activation, leading us to question what the Mos target might be if Mos is still required. We now demonstrate that Mos is indeed necessary, although is independent of the MAPK cascade, for conversion of inactive pre-MPF into active MPF. We have found that Myt1 is likely to be the Mos target in this process, as Mos interacts with Myt1 in oocyte extracts and Mos triggers Myt1 phosphorylation on some sites in vivo, even in the absence of MAPK activation. We propose that Mos is involved, not only in the MAPK cascade pathway, but also in a mechanism that directly activates MPF in Xenopus oocytes.

scholarly journals Leptin Enhances Oocyte Nuclear and Cytoplasmic Maturation via the Mitogen-Activated Protein Kinase Pathway

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 5355-5363 ◽  
Author(s):  
Jesse Craig ◽  
Hai Zhu ◽  
Paul W. Dyce ◽  
Jim Petrik ◽  
Julang Li
Keyword(s):  
Oocyte Maturation ◽  
Ovarian Function ◽  
Mapk Pathway ◽  
Physiological Role ◽  
Cyclin B1 ◽  
Mitogen Activated Protein Kinase ◽  
Female Reproduction ◽  
Oocyte Growth ◽  
Developmental Potential ◽  
Cytoplasmic Maturation

Abstract Recent studies have suggested that leptin has a central role in female reproduction, including ovarian function. The leptin receptor (Ob-R) has six isoforms and can signal through either the MAPK or the Janus-activated kinase/signal transducer and activator of transcription signal-transduction pathway, depending on the isoform. Expression of Ob-R has been reported in human and mouse oocytes; however, the physiological role of leptin during follicular development and oocyte maturation is largely unknown. In the current study, expression of Ob-R during oocyte growth and maturation was investigated in porcine oocytes from small, medium, and large follicles and in oocytes in the germinal vesicle (GV), GV breakdown, and metaphase II (MII) stages at both the mRNA and protein levels. The proportion of oocytes expressing Ob-R was maximal in oocytes from medium follicles and at the GV breakdown stage (P < 0.05), whereas the proportion of oocytes expressing the long isoform, Ob-Rb, was found to be consistently low throughout growth and maturation. When included in oocyte maturation medium, leptin significantly increased the proportion of oocytes reaching MII (P < 0.01), elevated cyclin B1 protein content in MII-stage oocytes (P < 0.05), and enhanced embryo developmental potential (P < 0.05), suggesting that leptin plays a role in both nuclear and cytoplasmic maturation. During oocyte maturation, leptin increased phosphorylated MAPK content by 2.8-fold (P < 0.05), and leptin-stimulated oocyte maturation was blocked when leptin-induced MAPK phosphorylation was suppressed by a specific MAPK activation inhibitor, U0126 (P < 0.01), demonstrating that leptin enhances nuclear maturation via activation of the MAPK pathway.

scholarly journals mos gene transforming efficiencies correlate with oocyte maturation and cytostatic factor activities.

1991 ◽  
Vol 11 (2) ◽  
pp. 604-610 ◽  
Author(s):  
N Yew ◽  
M Oskarsson ◽  
I Daar ◽  
D G Blair ◽  
G F Vande Woude
Keyword(s):  
Oocyte Maturation ◽  
Xenopus Oocytes ◽  
Kinase Activity ◽  
Vertebrate Species ◽  
3T3 Cells ◽  
Transforming Activity ◽  
Cytostatic Factor ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

The mos proto-oncogenes from different vertebrate species transform mouse NIH 3T3 cells with markedly different efficiencies. v-mos, mouse (c-mosmu), and chicken (c-mosch) mos transform NIH 3T3 cells 10- to 100-fold more efficiently than do human (c-moshu) and Xenopus (c-mosxc) mos. The mos genes with the highest transforming activity efficiently induce maturation in Xenopus oocytes and mimic cytostatic factor (CSF) by causing mitotic cleavage arrest in embryos. Chimeric v-mos/c-moshu proteins that had high transforming efficiencies in NIH 3T3 cells were also effective in the induction of oocyte maturation and CSF cleavage arrest. We measured the in vitro autophosphorylation activities of the different mos proteins and found that the levels of kinase activity of v-mos, c-mosmu, and c-mosch were much higher than that of c-mosxc. These data indicate that mos gene transforming efficiency and the ability to induce oocyte maturation or mimic CSF activity are correlated with in vitro autophosphorylation activity and suggest that the mos protein plays a similar role in transformed cells and normal oocytes.

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