Regulation of Wnt signal transduction

Abstract

Wnt signaling is essential during embryonic development and adult tissue homeostasis, controlling processes as diverse as cell proliferation, cell migration and differentiation.Wnt ligands can trigger different canonical or non-canonical signaling pathways depending on the receptors that are present on responding cells. One of these receptors is Ror, an evolutionarily conserved receptor tyrosine kinase with important functions in development and cancer. Key functions of Ror signaling are in cell migration and cell polarity, where it acts as a direct signaling receptor to control these processes. Studies in the nematodeCaenorhabditis elegans have shown, however, that it can also act indirectly by sequestering Wnt ligands away from responding cells. Although Ror signaling is considered a non-canonical Wnt signaling pathway, research in the past years has provided insight in the extensive cross-talk with other Wnt pathways, including the canonical Wnt/b-catenin signaling pathway. Here, we review what is currently known about Ror in vertebrate and Caenorhabditis elegans (C. elegans) development. Moreover, we discuss how insight into the cell non-autonomous function of Ror in C.elegans could further our understanding of the role of Ror in cancer.