10 - Cell Fate Determination and Signal Transduction during Caenorhabditis elegans Vulval Development

Abstract

How multiple intercellular signals are integrated by cells to generate a specific pattern of cell fates in a reproducible manner is the key to understand the development of multicellular organisms. Vulval development has proved to be an excellent model to study this question at the molecular level. Furthermore, since the specification of the vulval cell fates occurs in a set of epithelial precursor cells, the specific requirements for signaling processes to occur in polarized, asymmetric cells can be investigated. Cell fate determination during vulval development is thus likely to be generally applicable to more complex organisms. The vulva is formed by the 22 descendants of P5.p, P6.p, and P7.p, three of the 12 epithelial Pn.p cells that are positioned along the ventral midline of the animal. During wild-type vulval development, the anchor cell in the gonad induces P6.p to go through three rounds of symmetric cell divisions and generate 8 descendants—a lineage termed the primary (1°) cell fate. In response to the inductive anchor cell signal, P6.p sends a lateral signal that induces the secondary (2°) cell fate in the two adjacent P5.p and P7.p and prevents them from adopting the 1° cell fate.