Induction of metaphase arrest in cleaving Xenopus embryos by the protein kinase p90Rsk.
Before fertilization, vertebrate eggs are arrested in metaphase of meiosis II by cytostatic factor (CSF), an activity that requires activation of the mitogen-activated protein kinase (MAPK) pathway. To investigate whether CSF arrest is mediated by the protein kinase p90Rsk, which is phosphorylated and activated by MAPK, a constitutively activated (CA) form of Rsk was expressed in Xenopus embryos. Expression of CA Rsk resulted in cleavage arrest, and cytological analysis showed that arrested blastomeres were in M phase with prominent spindles characteristic of meiotic metaphase. Thus, Rsk appears to be the mediator of MAPK-dependent CSF arrest in vertebrate unfertilized eggs.
Gross
S D
SD
Howard Hughes Medical Institute and Department of Pharmacology, University of Colorado School of Medicine, Denver, CO 80262, USA.
Schwab
M S
MS
Lewellyn
A L
AL
Maller
J L
JL
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D001757:Blastomeres / Q000166:cytology* / Q000201:enzymology; D004789:Enzyme Activation; D020935:MAP Kinase Signaling System; D008540:Meiosis; D008677:Metaphase; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology / Q000201:enzymology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017231:Proto-Oncogene Proteins c-mos / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000648:ultrastructure; D014981:Xenopus
D012333:RNA, Messenger; D011994:Recombinant Proteins; D064413:3-Phosphoinositide-Dependent Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017231:Proto-Oncogene Proteins c-mos; D019893:Ribosomal Protein S6 Kinases; D020928:Mitogen-Activated Protein Kinases