MOM-4, a MAP kinase kinase kinase-related protein, activates WRM-1/LIT-1 kinase to transduce anterior/posterior polarity signals in C. elegans.

In C. elegans, a Wnt/WG-like signaling pathway down-regulates the TCF/LEF-related protein, POP-1, to specify posterior cell fates. Effectors of this signaling pathway include a beta-catenin homolog, WRM-1, and a conserved protein kinase, LIT-1. WRM-1 and LIT-1 form a kinase complex that can directly phosphorylate POP-1, but how signaling activates WRM-1/LIT-1 ...
kinase is not yet known. Here we show that mom-4, a genetically defined effector of polarity signaling, encodes a MAP kinase kinase kinase-related protein that stimulates the WRM-1/LIT-1-dependent phosphorylation of POP-1. LIT-1 kinase activity requires a conserved residue analogous to an activating phosphorylation site in other kinases, including MAP kinases. These findings suggest that anterior/posterior polarity signaling in C. elegans may involve a MAP kinase-like signaling mechanism.
Mesh Terms:
Amino Acid Sequence, Animals, Body Patterning, Caenorhabditis elegans, Caenorhabditis elegans Proteins, Conserved Sequence, Cytoskeletal Proteins, DNA-Binding Proteins, Embryo, Nonmammalian, Endoderm, Enzyme Activation, Helminth Proteins, High Mobility Group Proteins, Membrane Proteins, Molecular Sequence Data, Phosphorylation, Protein-Serine-Threonine Kinases, Sequence Alignment, Sequence Homology, Amino Acid, Signal Transduction, Transcription Factors
Mol. Cell
Date: Aug. 01, 1999
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