Protooncogene product, c-mos kinase, is involved in upregulating Na+/H+ antiporter in Xenopus oocytes.
Progesterone-stimulated Xenopus laevis oocytes undergo an increase in their intracellular pH from 7.3 to 7.7 because of the activation of Na+/H+ antiporters in their plasma membrane. Activation of Na+/H+ exchangers (NHE) in other cell systems appears to be regulated by phosphorylation of the NHE protein. In the current study we demonstrated that cytoplasm taken from steroid-stimulated oocytes rapidly induced an increase in intracellular pH when microinjected into full-grown stage VI recipient oocytes. The protein within the cytoplasm that appears to be responsible for this activity is c-mos kinase. Microinjected pure mosxe kinase protein rapidly activated the Na+/H+ exchangers in full-grown recipient oocytes. Furthermore, injected mosxe protein rapidly activated the Na+/H+ exchangers in smaller progesterone-insensitive stage IV oocytes. Therefore, it appears that the protooncogene product, p39 c-mos kinase, which is normally synthesized in full-grown stage VI oocytes in response to progesterone stimulation, is involved in the upregulation of the Na+/H+ antiporters during oocyte meiotic maturation.
Rezai
K
K
Department of Biology, Loyola University of Chicago, Illinois 60626.
Kulisz
A
A
Wasserman
W J
WJ
D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D005260:Female; D006863:Hydrogen-Ion Concentration; D016200:Maturation-Promoting Factor / Q000502:physiology; D009865:Oocytes / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology*; D015854:Up-Regulation; D014982:Xenopus laevis
D011518:Proto-Oncogene Proteins; D017923:Sodium-Hydrogen Exchangers; D003513:Cycloheximide; D011505:Protein-Tyrosine Kinases; D016200:Maturation-Promoting Factor