TGFβ-like signaling and spicule development in Caenorhabditis elegans

Abstract

A TGFβ-like signal is required for spicule development in Caenorhabditis elegans males. This signal appears to originate in the male- specific musculature and is required for the migrations of cells within the proctodeum. The migrations of these cells form cellular molds, the spicule traces, in which the cuticle of the spicules is secreted. Mutations in daf-4, sma-2, sma-3, and sma-4, which disrupt TGFβ-like signaling, result in aberrant migrations and morphologically abnormal spicules. daf-4, and hence the TGFβ-like signal, is required prior to or during cell migrations. Therefore, the TGFβ-like signal may act to prime the migrating cells or as a guidance cue. Mutations in lin-31 result in identical cell migration and spicule morphology defects. Thus, lin-31, which encodes a 'winged helix' protein (Miller et al., Genes Dev. 7, 933-947, 1993), may be a component of this TGFβ-like signaling pathway.