Dynamic smad-mediated BMP signaling revealed through transgenic zebrafish

Bone morphogenic protein (BMP) signaling is fundamental to development, injury response, and homeostasis. We have developed transgenic zebrafish that report Smad-mediated BMP signaling in embryos and adults. These lines express either enhanced green fluorescent protein (eGFP), destabilized eGFP, or destabilized Kusabira Orange 2 (KO2) under the well-characterized BMP Response Element (BRE). These fluorescent proteins were found to be expressed dynamically in regions of known BMP signaling including the developing tail bud, hematopoietic lineage, dorsal eye, brain structures, heart, jaw, fins, and somites, as well as other tissues. Responsiveness to changes in BMP signaling was confirmed by observing fluorescence after activation in an hsp70:bmp2b transgenic background or by inhibition in an hsp70:nog3 background. We further demonstrated faithful reportage by the BRE transgenic lines following chemical repression of BMP signaling using an inhibitor of BMP receptor activity, dorsomorphin. Overall, these lines will serve as valuable tools to explore the mechanisms and regulation of BMP signal during embryogenesis, in tissue maintenance, and during disease.