Signaling filopodia, termed cytonemes, are dynamic actin-based membrane structures that regulate the exchange of signaling molecules and their receptors within tissues. However, how cytoneme formation is regulated remains unclear. Here, we show that Wnt/PCP autocrine signaling controls the emergence of cytonemes, and that cytonemes subsequently control paracrine Wnt/β-catenin signal activation. Upon binding of the Wnt family member Wnt8a, the receptor tyrosine kinase Ror2 gets activated. Ror2/PCP signaling leads to induction of cytonemes, which mediate transport of Wnt8a to neighboring cells. In the Wnt receiving cells, Wnt8a on cytonemes triggers Wnt/β-catenin-dependent gene transcription and proliferation. We show that cytoneme-based Wnt transport operates in diverse processes, including zebrafish development, the murine intestinal crypt, and human cancer organoids, demonstrating that Wnt transport by cytonemes and its control via the Ror2 pathway is highly conserved in vertebrates.

Data from Mattes 2018Kinase Screen and automated image-analysis identifies the receptor tyrosine kinase Ror2 as a potential cytoneme regulator upstream of Cdc42. Wnt8a-GFP and a membrane bound mCherry was co-transfected with kinase library genes in Pac2 cells in a 96-well plate. Images were acquired automatically and analyzed for filopodia length and numbers by a filopodia detection software. Automated Image analysis software detects and counts filopodia of single cells using the memCherry signal and quantifies their length by automatically tracing the tips back to the cell body. Table shows transfected kinase genes and their relative filopodia number/cell and length.Screening Results Mattes 2018.xlsx