Mitogen-activated protein kinase kinase is required for the mos-induced metaphase arrest.
The product of the c-mos proto-oncogene functions not only as an initiator of oocyte maturation but also as a component of cytostatic factor that causes the natural arrest of the unfertilized egg at the second meiotic metaphase. It has been shown that Mos can phosphorylate and activate mitogen-activated protein (MAP) kinase kinase (MAPKK) in vitro, leading to activation of MAP kinase. In this study, by using an anti-MAPKK antibody that can specifically inhibit Xenopus MAPKK activity, we have shown that MAPKK mediates the cytostatic factor activity of Mos. Coinjection of this anti-MAPKK antibody with the bacterially expressed Mos protein into a two-cell embryo prevented the Mos-induced cleavage arrest as well as the Mos-induced MAP kinase activation. The analysis of individual embryos indicated that the degree of the cleavage arrest was correlated with the extent of the MAP kinase activation in the Mos- and the Mos/antibody-injected embryos. These observations suggest the involvement of a signal transmission pathway consisting of Mos, MAPKK, and MAP kinase in the metaphase arrest.
Kosako
H
H
Department of Genetics and Molecular Biology, Kyoto University, Japan.
Gotoh
Y
Y
Nishida
E
E
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001755:Blastocyst / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002474:Cell-Free System; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008540:Meiosis; D008677:Metaphase; D020929:Mitogen-Activated Protein Kinase Kinases; D009865:Oocytes / Q000166:cytology* / Q000201:enzymology*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D017231:Proto-Oncogene Proteins c-mos / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D014982:Xenopus laevis
D000906:Antibodies; D047428:Protein Kinase Inhibitors; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D011494:Protein Kinases; D017231:Proto-Oncogene Proteins c-mos; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases