title: Induction of metaphase arrest in cleaving Xenopus embryos by MAP kinase.
abstract: The natural arrest of vertebrate unfertilized eggs in second meiotic metaphase results from the activity of cytostatic factor (CSF). The product of the c-mos(xe) proto-oncogene is thought to be a component of CSF and can induce metaphase arrest when injected into blastomeres of two-cell embryos. The c-Mos(xe) protein can directly activate the mitogen-activated protein kinase kinase (MAP kinase kinase) in vitro, leading to activation of MAP kinase. MAP kinase and c-Mos(xe) are active in unfertilized eggs and are rapidly inactivated after fertilization. Microinjection of thiophosphorylated MAP kinase into one blastomere of a two-cell embryo induced metaphase arrest similar to that induced by c-Mos(xe). However, only arrest with c-Mos(xe) was associated with activation of endogenous MAP kinase. These results indicate that active MAP kinase is a component of CSF in Xenopus and suggest that the CSF activity of c-Mos(xe) is mediated by MAP kinase.
authors.affiliation: Howard Hughes Medical Institute, University of Colorado School of Medicine, Denver 80262.
authors.forename: O
authors.initials: O
authors.lastname: Haccard
authors.forename: B
authors.initials: B
authors.lastname: Sarcevic
authors.forename: A
authors.initials: A
authors.lastname: Lewellyn
authors.forename: R
authors.initials: R
authors.lastname: Hartley
authors.forename: L
authors.initials: L
authors.lastname: Roy
authors.forename: T
authors.initials: T
authors.lastname: Izumi
authors.forename: E
authors.initials: E
authors.lastname: Erikson
authors.forename: J L
authors.initials: JL
authors.lastname: Maller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001757:Blastomeres / Q000166:cytology* / Q000378:metabolism; D004789:Enzyme Activation; D008677:Metaphase; D019950:Mitogen-Activated Protein Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D017231:Proto-Oncogene Proteins c-mos / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017231:Proto-Oncogene Proteins c-mos; D019950:Mitogen-Activated Protein Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases