The Wnt co-receptor PTK7/Otk in Neurogenesis and Patterning

Wnt signaling is a highly conserved metazoan pathway that plays a crucial role in cell-fate determination and morphogenesis during development. Wnt ligands can induce disparate cellular responses. The exact mechanism behind these different outcomes is not fully understood but may be due to interactions with different receptors on the cell membrane. PTK7/Otk is a transmembrane receptor that is implicated in various developmental and physiological processes including cell polarity, cell migration, and invasion. Here we examine two roles of Otk1 and Otk2 in patterning and neurogenesis. We find that Otk1 is a positive regulator of signaling and Otk2 functions as its inhibitor. We propose that PTK7/Otk functions in signaling and in particular cell migration and polarity contributing to the diversity of cellular responses seen in Wnt-mediated processes. Overall design: To investigate the function of Wnt4, Otk1 and Otk2 in Drosophila embryos, we used the UAS and RNAi systems in Drosophila to upregulate and downregulate the expression of these target genes. Two replicates were sequenced per condition.