A major goal of my research program is to identify molecules and metabolic pathways that participate in the control of oocyte maturation in mammals. In our model for meiotic induction, gonadotropin triggers an increase in cAMP phosphodiesterase (PDE) that induces meiotic resumption by both a loss of cAMP-dependent protein kinase activity and an increase in AMP-activated protein kinase (AMPK) activity. The oocyte-cumulus cell complex, isolated from mice 48 h after hormonal priming, will be used as the principal model system, but oocytes induced to mature in vivo by hCG injection will also be examined. Isoform-specific PDE inhibitors will be used to manipulate meiosis according to the cellular target site, and PDE activity will be measured to test for a cause-and-effect relationship with maturation-promoting factor (MPF; measured as histone H1 kinase activity) and germinal vesicle breakdown (GVB). Western analysis of AMPK (beta, gamma subunits) in complexes will be completed, and the temporal relationship between AMPK activation, MPF activation and GVB during spontaneous maturation or maturation induced by adenosine analogs or hormones will be tested. Oocyte microinjection will determine if active AMPK induces GVB and if antibodies to alpha subunits antagonize meiotic induction. Antisera to alpha subunits of AMPK as well as an anti-phosphoantibody to active AMPK will be employed to localize the enzyme in oocytes by indirect immunofluorescence during meiotic resumption. We will also investigate the potential role of ERK1/2 and p38 mitogen-activated protein kinases in mediating the meiosis-inducing action of AMPK. These results will help delineate specific metabolic pathways involved in meiotic maturation and will have important implications for both fertility and contraception, since each is affected by the ability of the oocyte to successfully initiate and complete meiotic maturation. They may also help in preventing or minimizing erroneous meiotic control that can give rise to aneuploidy and its disastrous consequences. Furthermore, these studies will benefit the development of in vitro systems where either meiotic arrest or completion of meiotic maturation is the desired endpoint.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD040392-05
Application #
7213230
Study Section
Reproductive Biology Study Section (REB)
Program Officer
Tasca, Richard J
Project Start
2003-04-02
Project End
2009-03-31
Budget Start
2007-04-01
Budget End
2009-03-31
Support Year
5
Fiscal Year
2007
Total Cost
$154,672
Indirect Cost
Name
Marquette University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
046929621
City
Milwaukee
State
WI
Country
United States
Zip Code
53201
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Downs, Stephen M; Mosey, Jessica L; Klinger, Jonathan (2009) Fatty acid oxidation and meiotic resumption in mouse oocytes. Mol Reprod Dev 76:844-53
Chen, Jing; Chi, Maggie M; Moley, Kelle H et al. (2009) cAMP pulsing of denuded mouse oocytes increases meiotic resumption via activation of AMP-activated protein kinase. Reproduction 138:759-70
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Downs, Stephen M; Chen, Jing (2006) Induction of meiotic maturation in mouse oocytes by adenosine analogs. Mol Reprod Dev 73:1159-68
Chen, Jing; Hudson, Emma; Chi, Maggie M et al. (2006) AMPK regulation of mouse oocyte meiotic resumption in vitro. Dev Biol 291:227-38
Downs, Stephen M; Gilles, Ryan; Vanderhoef, Christopher et al. (2006) Differential response of cumulus cell-enclosed and denuded mouse oocytes in a meiotic induction model system. Mol Reprod Dev 73:379-89
LaRosa, Cean; Downs, Stephen M (2005) MEK inhibitors block AICAR-induced maturation in mouse oocytes by a MAPK-independent mechanism. Mol Reprod Dev 70:235-45