Regulation of spontaneous and induced resumption of meiosis in mouse oocytes by different intracellular pathways

Reproduction ◽  
2000 ◽  
pp. 377-383 ◽  
Author(s):  
L Leonardsen ◽  
A Wiersma ◽  
M Baltsen ◽  
AG Byskov ◽  
CY Andersen
Keyword(s):  
Signal Transduction ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Mitogen Activated Protein Kinase ◽  
Meiotic Maturation ◽  
Mouse Oocytes ◽  
Mitogen Activated Protein ◽  
Dependent Signal ◽  
Kinase Pathway ◽  
Kinase A

The mitogen-activated protein kinase-dependent and the cAMP-protein kinase A-dependent signal transduction pathways were studied in cultured mouse oocytes during induced and spontaneous meiotic maturation. The role of the mitogen-activated protein kinase pathway was assessed using PD98059, which specifically inhibits mitogen-activated protein kinase 1 and 2 (that is, MEK1 and MEK2), which activates mitogen-activated protein kinase. The cAMP-dependent protein kinase was studied by treating oocytes with the protein kinase A inhibitor rp-cAMP. Inhibition of the mitogen-activated protein kinase pathway by PD98059 (25 micromol l(-1)) selectively inhibited the stimulatory effect on meiotic maturation by FSH and meiosis-activating sterol (that is, 4,4-dimethyl-5alpha-cholest-8,14, 24-triene-3beta-ol) in the presence of 4 mmol hypoxanthine l(-1), whereas spontaneous maturation in the absence of hypoxanthine was unaffected. This finding indicates that different signal transduction mechanisms are involved in induced and spontaneous maturation. The protein kinase A inhibitor rp-cAMP induced meiotic maturation in the presence of 4 mmol hypoxanthine l(-1), an effect that was additive to the maturation-promoting effect of FSH and meiosis-activating sterol, indicating that induced maturation also uses the cAMP-protein kinase A-dependent signal transduction pathway. In conclusion, induced and spontaneous maturation of mouse oocytes appear to use different signal transduction pathways.

106 EXPRESSION PATTERNS OF PROTEIN KINASE A SUBUNITS DURING MEIOTIC MATURATION OF PORCINE OOCYTES

2008 ◽  
Vol 20 (1) ◽  
pp. 133
Author(s):  
J. S. Kim ◽  
Y. S. Cho ◽  
B. S. Song ◽  
X. L. Jin ◽  
K. K. Lee ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Expression Patterns ◽  
Mitogen Activated Protein Kinase ◽  
Meiotic Maturation ◽  
Type I ◽  
Type Ii ◽  
Regulatory Subunits ◽  
Mitogen Activated Protein ◽  
Kinase A

Many extracellular ligands activate adenylyl cyclase and then alter the intracellular concentrations of the second messenger, cAMP. High intracellular concentrations of cAMP activate cAMP-dependent protein kinase A (PKA), which regulates the meiotic arrest of oocytes at the germinal vesicle (GV) stage. In this study, we investigated the expression patterns of PKA subunits in porcine oocytes during meiotic maturation. Porcine oocytes were matured in the NCSU-23 medium supplemented with 10% (v/v) porcine follicular fluid, 10 ng mL–1 of EGF, 25 µm β-mercaptoethanol, 0.57 mm cysteine, 10 IU mL–1 of pregant mare serum gonadotropin, 10 IU mL–1 of hCG, 1 mm dbcAMP for 22 h and further cultured without dbcAMP and hormone for 22 h. All experiments were repeated more than 3 times. All data were analyzed by using Duncan's test of ANOVA by Statistical Analysis System (SAS Institute Inc., Cary, NC, USA). We found that the expression of type I and type II regulatory subunits (RI and RII) of PKA were higher in the GV stage than those of metaphase II stage porcine oocytes. In addition, their expressions were dynamically changed from the metaphase I to metaphase II stage. The expression levels of PKA regulatory subunits type I and type II were evaluated byWestern blot analysis by using specific antibodies such as anti-PKAc, anti-PKARIα, anti-PKARIIα, and anti-PKARIIβ in porcine GV and metaphase II oocytes (n = 25). To confirm the relationship between PKA and cell cycle regulators such as MPF or MAPK during meiosis, the expression of maturation-promoting factor or mitogen-activated protein kinase were examined by Western blot with anti-cdc2 or anti-ERK1/2. The expressions of the RI and RII subunits of PKA were decreased, whereas the expression of maturation-promoting factor (cdc2) or mitogen-activated protein kinase (ERK1/2) were increased in metaphase II stage oocytes. In conclusion, our findings indicate that the dynamic change of PKA subunits plays an important role not only in cAMP/PKA signaling pathway but also in the regulation of meiotic progression beyond the metaphase II stage in porcine oocytes.

scholarly journals Protein Kinase A Operates a Molecular Switch That Governs Yeast Pseudohyphal Differentiation

2002 ◽  
Vol 22 (12) ◽  
pp. 3981-3993 ◽  
Author(s):  
Xuewen Pan ◽  
Joseph Heitman
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Pathogenic Fungi ◽  
Mitogen Activated Protein Kinase ◽  
Signaling Cascades ◽  
Mitogen Activated Protein ◽  
Eukaryotic Organisms ◽  
Pseudohyphal Differentiation ◽  
Developmental Switch ◽  
Kinase A

ABSTRACT The yeast Saccharomyces cerevisiae undergoes a dimorphic filamentous transition in response to nutrient cues that is affected by both mitogen-activated protein kinase and cyclic AMP-protein kinase A signaling cascades. Here two transcriptional regulators, Flo8 and Sfl1, are shown to be the direct molecular targets of protein kinase A. Flo8 and Sfl1 antagonistically control expression of the cell adhesin Flo11 via a common promoter element. Phosphorylation by the protein kinase A catalytic subunit Tpk2 promotes Flo8 binding and activation of the Flo11 promoter and relieves repression by prohibiting dimerization and DNA binding by Sfl1. Our studies illustrate in molecular detail how protein kinase A combinatorially effects a key developmental switch. Similar mechanisms may operate in pathogenic fungi and more complex multicellular eukaryotic organisms.

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