A novel MAP kinase phosphatase is localised in the branchial arch region and tail tip of Xenopus embryos and is inducible by retinoic acid.
Using a differential display strategy, we have isolated a cDNA corresponding to a mRNA which is induced by retinoic acid treatment of late gastrula Xenopus embryos, and much more strongly induced by retinoic acid and cycloheximide. The cDNA, designated X17C, encodes a novel mitogen-activated protein (MAP) kinase phosphatase of 378 amino acid residues which is only distantly related to other known MAP kinase phosphatases. In normal embryogenesis, the X17C mRNA is expressed after the midblastula transition and accumulates during gastrulation. In neurula and tailbud stage embryos the mRNA is localised in two domains, one in the anterior region of the embryo, and one at the tail tip. When expressed from synthetic mRNA injected into oocytes, the X17C protein is found within the cytosolic fraction and not in the nucleus. The X17C protein dephosphorylates and inactivates Xenopus MAP kinase in oocytes stimulated to undergo maturation by progesterone. We indicate the application of X17C as a tool for interfering with MAP kinase signaling in somatic cells of embryos, using FGF receptor-mediated MAP kinase activation in animal cap explants.
Mason
C
C
Department of Biological Sciences, University of Warwick, Coventry, UK.
Lake
M
M
Nebreda
A
A
Old
R
R
D000595:Amino Acid Sequence; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000032:analysis / Q000235:genetics*; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000201:enzymology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D007641:Keratolytic Agents / Q000494:pharmacology*; D008969:Molecular Sequence Data; D014212:Tretinoin / Q000494:pharmacology*; D014981:Xenopus / Q000196:embryology*
D007641:Keratolytic Agents; D014212:Tretinoin; D017871:Calcium-Calmodulin-Dependent Protein Kinases