In early C. elegans embryos, signaling between a posterior blastomere, P2, and a ventral blastomere, EMS, specifies endoderm and orients the division axis of the EMS cell. Although Wnt signaling contributes to this polarizing interaction, no mutants identified to date abolish P2/EMS signaling. Here, we show that two tyrosine kinase-related genes, src-1 and mes-1, are required for the accumulation of phosphotyrosine between P2 and EMS. Moreover, src-1 and mes-1 mutants strongly enhance endoderm and EMS spindle rotation defects associated with Wnt pathway mutants. SRC-1 and MES-1 signal bidirectionally to control cell fate and division orientation in both EMS and P2. Our findings suggest that Wnt and Src signaling function in parallel to control developmental outcomes within a single responding cell.
Bei, Y., Hogan, J., Berkowitz, L. A., Soto, M., Rocheleau, C. E., Pang, K. M., … Mello, C. C. (2002). SRC-1 and Wnt signaling act together to specify endoderm and to control cleavage orientation in early C. elegans embryos. Developmental Cell, 3(1), 113–125. https://doi.org/10.1016/S1534-5807(02)00185-5