Progesterone-induced changes in the phosphoryl potential during the meiotic divisions in amphibian oocytes: Role of Na/K-ATPase

Abstract

BackgroundProgesterone triggers resumption of the first meiotic division in the Rana pipiens oocyte by binding to the N-terminal external loop of the catalytic subunit of Na/K-ATPase, releasing a cascade of lipid second messengers. This is followed by internalization of specific membrane proteins, plasma membrane depolarization and nuclear membrane breakdown, culminating in arrest at second metaphase.ResultsProgesterone initiates an increase in phosphoryl potential during the first meiotic division, resulting in the accumulation of high energy protein phosphate by second metaphase arrest. 31P-NMR, with saturation transfer, demonstrates that the phosphocreatine level rises ~2 fold and that the "pseudo" first order rate constant for the creatine kinase reaction falls to ~20% of the control by the onset of nuclear membrane breakdown. 32PO4 pulse-labeling reveals a net increase in phosphorylation of yolk protein phosvitin during this period. The increased yolk protein phosphorylation coincides with internalization of membrane Na/K-ATPase and membrane depolarizatioConclusionsThese results indicate that progesterone binding to the catalytic subunit of the Na-pump diverts ATP from cation regulation at the plasma membrane to storage of high energy phosphate in yolk protein. Phosvitin serves as a major energy source during fertilization and early cleavage stages and is also a storage site for cations (e.g. Na+, K+, Ca2+, Fe2+/3+) essential for embryonic development.

Plasma membrane events associated with the meiotic divisions in the amphibian oocyte: insights into the evolution of insulin transduction systems and cell signaling

“…A role for lipid rafts in meiosis is further supported by the finding by Sadler and Jacobs [55] that treatment of Xenopus oocytes with the cholesterol-depleting drug, methyl-β-cyclodextrin, removed 50–70% of cell-associated 3 H]cholesterol and accelerated the progesterone response. We find that progesterone induces net internalization of 40–50% of the oocyte surface containing >95% of the Na + /K + -ATPase α-subunit just prior to nuclear membrane breakdown [8], consistent with a loss of membrane caveolin-rich rafts.…”

“…Pulse-chase experiments followed by extraction and chromatography of the cytosol and constant binding fractions demonstrated that 14 C]inulin was internalized but not bound or metabolized. Comparison of membrane-sequestered 125 I]insulin with that of 14 C]inulin, suggests that the membrane constant binding fraction is contained within the numerous endocytotic vesicles seen in electron micrographs of the fully grown prophase oocyte [7,8]. …”

“…Follicles were loosely packed in a 10 mm diameter tube and superfused with aerated Ringer’s solution at 20–21°C (see [8]). 31 P-NMR spectra were recorded at 81 MHz with a Varian VXR-200 and pH i measured as described previously [25].…”

“…Superfusion of isolated oocytes or follicles in an NMR tube maintains physiological oxygen levels and allows analysis of changes in bioenergetics, intracellular cation levels and in membrane conductance (e.g. [8]).…”

The Transcriptomes of the Crucian Carp Complex (Carassius auratus) Provide Insights into the Distinction between Unisexual Triploids and Sexual Diploids

“…This pathway is reported to increase the maturation promoting factor (MPF) [ 26 ], which might lead to the tripolar spindle formation and the later modification of microtubule dynamics [ 27 ]. The enriched GO terms in this fish, concerned with transferase activity and the transferring phosphorus-containing groups, are much related involved in the enriched progesterone-mediated oocyte maturation pathway [ 28 ]. The ubiquitin-mediated proteolysis pathway and the Fanconi Anemia pathway were also significantly enriched in gibel carp.…”