A p90(rsk) mutant constitutively interacting with MAP kinase uncouples MAP kinase from p34(cdc2)/cyclin B activation in Xenopus oocytes.
The efficient activation of p90(rsk) by MAP kinase requires their interaction through a docking site located at the C-terminal end of p90(rsk). The MAP kinase p42(mpk1) can associate with p90(rsk) in G(2)-arrested but not in mature Xenopus oocytes. In contrast, an N-terminally truncated p90(rsk) mutant named D2 constitutively interacts with p42(mpk1). In this report we show that expression of D2 inhibits Xenopus oocyte maturation. The inhibition requires the p42(mpk1) docking site. D2 expression uncouples the activation of p42(mpk1) and p34(cdc2)/cyclin B in response to progesterone but does not prevent signaling through p90(rsk). Instead, D2 interferes with a p42(mpk1)-triggered pathway, which regulates the phosphorylation and activation of Plx1, a potential activator of the Cdc25 phosphatase. This new pathway that links the activation of p42(mpk1) and Plx1 during oocyte maturation is independent of p34(cdc2)/cyclin B activity but requires protein synthesis. Using D2, we also provide evidence that the sustained activation of p42(mpk1) can trigger nuclear migration in oocytes. Our results indicate that D2 is a useful tool to study MAP kinase function(s) during oocyte maturation. Truncated substrates such as D2, which constitutively interact with MAP kinases, may also be helpful to study signal transduction by MAP kinases in other cellular processes.
Gavin
A C
AC
European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
Ni Ainle
A
A
Chierici
E
E
Jones
M
M
Nebreda
A R
AR
D000818:Animals; D001665:Binding Sites; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D016200:Maturation-Promoting Factor / Q000494:pharmacology; D008540:Meiosis / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D010766:Phosphorylation; D011374:Progesterone / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017231:Proto-Oncogene Proteins c-mos / Q000378:metabolism; D019893:Ribosomal Protein S6 Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D015398:Signal Transduction / Q000187:drug effects; D029867:Xenopus Proteins; D014982:Xenopus laevis; D000097869:Polo-Like Kinase 1
D016203:CDC2 Protein Kinase; D018797:Cell Cycle Proteins; D019926:Cyclin B; D016200:Maturation-Promoting Factor; D019950:Mitogen-Activated Protein Kinase 1; D011374:Progesterone; D017346:Protein Serine-Threonine Kinases; D017231:Proto-Oncogene Proteins c-mos; D019893:Ribosomal Protein S6 Kinases; D029867:Xenopus Proteins; C101085:Plk1 protein, Xenopus; D000097869:Polo-Like Kinase 1