Inhibition of protein tyrosine phosphatases blocks calcium-induced activation of metaphase II-arrested oocytes of Xenopus laevis.
We have studied the effect of a protein tyrosine phosphatases (PTP) inhibitor on calcium-induced activation of Xenopus laevis oocytes arrested at metaphase II. Ammonium molybdate microinjection blocked pronucleus formation following A23187 treatment while cortical granules still underwent exocytosis. Pronuclei still occurred in ammonium molybdate-injected oocytes following 6-DMAP addition. Changes that usually occurred following A23187 exposure were inhibited in the presence of ammonium molybdate in the oocyte: MAPK dephosphorylation, p34(cdc2) rephosphorylation and cyclin B2 and p39(mos) proteolysis. These results suggest that a PTP is involved in the activation of the ubiquitin-dependent degradation machinery.
Bodart
J F
JF
Centre de Biologie Cellulaire, Laboratoire de Biologie du Développement, UPRES EA 1033, Université de Lille 1, SN3, F-59655, Villeneuve d'Ascq, France.
Béchard
D
D
Bertout
M
M
Rousseau
A
A
Gannon
J
J
Vilain
J P
JP
Flament
S
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016200:Maturation-Promoting Factor / Q000032:analysis; D008677:Metaphase / Q000187:drug effects / Q000502:physiology*; D008982:Molybdenum / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017231:Proto-Oncogene Proteins c-mos / Q000032:analysis; D014982:Xenopus laevis
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D000001:Calcimycin; D008982:Molybdenum; D017231:Proto-Oncogene Proteins c-mos; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016200:Maturation-Promoting Factor; D017027:Protein Tyrosine Phosphatases; C022175:ammonium molybdate; D002118:Calcium