Release from Xenopus oocyte prophase I meiotic arrest is independent of a decrease in cAMP levels or PKA activity.
Vertebrate oocytes arrest at prophase of meiosis I as a result of high levels of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) activity. In Xenopus, progesterone is believed to release meiotic arrest by inhibiting adenylate cyclase, lowering cAMP levels and repressing PKA. However, the exact timing and extent of the cAMP decrease is unclear, with conflicting reports in the literature. Using various in vivo reporters for cAMP and PKA at the single-cell level in real time, we fail to detect any significant changes in cAMP or PKA in response to progesterone. More interestingly, there was no correlation between the levels of PKA inhibition and the release of meiotic arrest. Furthermore, we devised conditions whereby meiotic arrest could be released in the presence of sustained high levels of cAMP. Consistently, lowering endogenous cAMP levels by >65% for prolonged time periods failed to induce spontaneous maturation. These results argue that the release of oocyte meiotic arrest in Xenopus is independent of a reduction in either cAMP levels or PKA activity, but rather proceeds through a parallel cAMP/PKA-independent pathway.
Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144.
Nancy
N
Nader
Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144.
Raphael
R
Courjaret
Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144.
Maya
M
Dib
Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144.
Rashmi P
RP
Kulkarni
Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144 khm2002@qatar-med.cornell.edu.
Khaled
0000-0001-6215-2411
K
Machaca
D000818:Animals; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D049469:Meiotic Prophase I / Q000187:drug effects; D008954:Models, Biological; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism*
D054815:Cyclic Nucleotide-Gated Cation Channels; D029867:Xenopus Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D011374:Progesterone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases
Oocyte maturation; PKA; Progesterone; Xenopus; cAMP