PT - JOURNAL ARTICLE AU - Jahnavi Suresh AU - Nathan Harmston AU - Ka Keat Lim AU - Prameet Kaur AU - Helen Jingshu Jin AU - Jay B. Lusk AU - Enrico Petretto AU - Nicholas S. Tolwinski TI - An embryonic system to assess Wnt transcriptional targets AID - 10.1101/129056 DP - 2017 Jan 01 TA - bioRxiv PG - 129056 4099 - http://biorxiv.org/content/early/2017/04/21/129056.short 4100 - http://biorxiv.org/content/early/2017/04/21/129056.full AB - During animal development, complex signals determine and organize a vast number of tissues using a very small number of signal transduction pathways. These developmental signaling pathways determine cell fates through a coordinated transcriptional response that remains poorly understood. The Wnt pathway is involved in a variety of these cellular functions, and its signals are transmitted in part through a β-catenin/TCF transcriptional complex. Here we report an in vivo Drosophila assay that can be used to distinguish between activation, de-repression and repression of transcriptional responses, separating upstream and downstream pathway activation and canonical/non-canonical Wnt signals in embryos. We find specific sets of genes downstream of both β-catenin and TCF with an additional group of genes regulated by Wnt, while the non-canonical Wnt4 regulates a separate cohort of genes. We correlate transcriptional changes with phenotypic outcomes of cell differentiation and embryo size, showing our model can be used to characterize developmental signaling compartmentalization in vivo.