Patterning of the C-elegans 1 degrees vulval lineage by RAS and Wnt pathways

In C, elegans, the descendants of the 1 degrees vulval precursor cell (VPC) establish, a fixed spatial pattern of two different cell fates: E-F-F-E, T he two inner granddaughters attach to the somatic gonadal anchor cell (AC) and generate four vulF cells, while the two outer granddaughters produce fo ur vulE progeny. zmp-1::GFP, a molecular marker that distinguishes these tw o fates, is expressed in vulE cells, but not vulF cells. We demonstrate tha t a short-range AC signal is required to ensure that the pattern of vulE an d vulF fates is properly established. In addition, signaling between the in ner and outer 1 degrees VPC descendants, as well as intrinsic polarity of t he 1 degrees VPC daughters, is involved in the asymmetric divisions of the 1 degrees VPC daughters and the proper orientation of the outcome. Finally, we provide evidence that RAS signaling is used during this new AC signalin g event, while the Wnt receptor LIN-17 appears to mediate signaling between the inner and outer 1 degrees VPC descendants.