MOM-4, a MAP Kinase Kinase Kinase–Related Protein, Activates WRM-1/LIT-1 Kinase to Transduce Anterior/Posterior Polarity Signals in C. elegans

• Published in: Molecular cell Vol. 4; no. 2; pp. 275 - 280
• Main Authors: Shin, Tae Ho, Yasuda, Jun, Rocheleau, Christian E., Lin, Rueyling, Soto, Martha, Bei, Yanxia, Davis, Roger J., Mello, Craig C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-08-1999
• Subjects: Amino Acid Sequence; Animals; Body Patterning; Caenorhabditis elegans; Caenorhabditis elegans - embryology; Caenorhabditis elegans - genetics; Caenorhabditis elegans Proteins; Conserved Sequence; Cytoskeletal Proteins - metabolism; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - metabolism; Embryo, Nonmammalian - physiology; Endoderm - physiology; Enzyme Activation; Helminth Proteins - metabolism; High Mobility Group Proteins - chemistry; High Mobility Group Proteins - metabolism; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Molecular Sequence Data; Phosphorylation; Protein-Serine-Threonine Kinases - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Signal Transduction; Transcription Factors - metabolism
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/S1097-2765(00)80375-5

In
C. elegans, a Wnt/WG-like signaling pathway downregulates the TCF/LEF-related protein, POP-1, to specify posterior cell fates. Effectors of this signaling pathway include a β-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.