Anderson, W. K. | Search bioRxiv

bioRxiv2026

A transgenic zebrafish for direct optogenetic activation of FGF/ERK signaling

Dynamic FGF/ERK signaling plays key roles in development, regeneration, and disease. We recently developed a zebrafish-optimized optogenetic tool, bOpto-FGF, that enables reversible activation of FGF/ERK signaling in response to blue light ([~]455 nm) by fusing a zebrafish receptor tyrosine kinase domain to the blue light-dimerizing LOV domain. Previously, this tool was introduced into zebrafish embryos by mRNA injection. Here, we develop Tg(ubi:bOpto-FGF), a novel transgenic zebrafish ubiquitously expressing bOpto-FGF, to streamline experimental workflows. We demonstrate robust blue light-mediated activation of FGF/ERK signaling and FGF target gene expression in early gastrulation-stage Tg(ubi:bOpto-FGF) embryos. Light-mediated signaling activation at this stage is more spatially uniform in transgenics compared to mRNA-injected embryos, and ectopic signaling in response to continuous light exposure is activated within 3 minutes and maintained for at least 75 minutes. Further, Tg(ubi:bOpto-FGF) heterozygotes are light-responsive from late blastula stages through at least 24 hours post-fertilization. Finally, we demonstrate light-mediated spatially localized FGF/ERK signaling activation within 1 minute in the head, trunk, and tail at 1 day post-fertilization. This transgenic line provides a powerful and convenient new strategy for spatiotemporal manipulation of FGF/ERK signaling dynamics in the vertebrate zebrafish model. Summary StatementNovel transgenic zebrafish provides precise optogenetic control of a key developmental signaling pathway in vivo

developmental biology↗

bioRxiv2025

An optogenetic toolkit for robust activation of FGF, BMP, and Nodal signaling in zebrafish

Cell signaling regulates a wide range of biological processes including development, homeostasis, and disease. Accessible technologies to precisely manipulate signaling have important applications in basic and translational research. Here, we present an optogenetic toolkit for signaling manipulation in zebrafish embryos. We introduce a zebrafish-optimized optogenetic FGF signaling activator and a single-transcript Nodal signaling activator, and assess them together with a previously established BMP signaling activator. We thoroughly characterize this suite of tools and demonstrate light-dependent spatiotemporal control of signaling in vivo. In response to [~]455 nm (blue) light, zebrafish receptor kinase domains fused to blue light-dimerizing LOV domains enable robust signaling activation with minimal inadvertent activity in the dark or at wavelengths over 495 nm. Each optogenetic tool initiates pathway-specific signaling and activates known target genes. Signaling is activated with rapid on/off kinetics, and activation strength can be tuned by adjusting light irradiance. Finally, we demonstrate spatially localized signaling activation in vivo. Together, our results establish this optogenetic toolkit as a potent experimental platform and provide guidelines for rapid, direct, and adjustable activation of FGF, BMP, and Nodal signaling in zebrafish embryos.

developmental biology↗