Optogenetic inhibition of Delta reveals digital Notch signalling output during tissue differentiation

• Published in: EMBO reports Vol. 20; no. 12; pp. e47999 - n/a
• Main Authors: Viswanathan, Ranjith, Necakov, Aleksandar, Trylinski, Mateusz, Harish, Rohit Krishnan, Krueger, Daniel, Esposito, Emilia, Schweisguth, Francois, Neveu, Pierre, De Renzis, Stefano
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05.12.2019; Springer Nature B.V; EMBO Press; John Wiley and Sons Inc
• Subjects: Animals; Animals, Genetically Modified; Cell activation; Cell Differentiation; Clustering; Development Biology; Differentiation (biology); Drosophila melanogaster - genetics; Drosophila melanogaster - growth & development; Drosophila melanogaster - metabolism; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; EMBO11; EMBO22; Fruit flies; Gene expression; Genes, Insect; Genome editing; Genomes; Insects; Intracellular Signaling Peptides and Proteins - antagonists & inhibitors; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Kinases; Life Sciences; Loci; Membrane Proteins - antagonists & inhibitors; Membrane Proteins - genetics; Membrane Proteins - metabolism; morphogenesis; Mutation; Notch protein; Notch signalling; Optogenetics; Perturbation methods; Phenotype; Receptors, Notch - genetics; Receptors, Notch - metabolism; signal dynamics; Signal Transduction; Signaling; Spatio-Temporal Analysis; tissue differentiation; Tissues; Transcription; signal dynamics; morphogenesis; Notch signalling; optogenetics; tissue differentiation; tissue differentiation Subject Categories Development; Methods & Resources
• ISSN: 1469-221X; 1469-3178; 1469-3178
• DOI: 10.15252/embr.201947999

Spatio‐temporal regulation of signalling pathways plays a key role in generating diverse responses during the development of multicellular organisms. The role of signal dynamics in transferring signalling information in vivo is incompletely understood. Here, we employ genome engineering in Drosophila melanogaster to generate a functional optogenetic allele of the Notch ligand Delta (opto‐Delta), which replaces both copies of the endogenous wild‐type locus. Using clonal analysis, we show that optogenetic activation blocks Notch activation through cis ‐inhibition in signal‐receiving cells. Signal perturbation in combination with quantitative analysis of a live transcriptional reporter of Notch pathway activity reveals differential tissue‐ and cell‐scale regulatory modes. While at the tissue‐level the duration of Notch signalling determines the probability with which a cellular response will occur, in individual cells Notch activation acts through a switch‐like mechanism. Thus, time confers regulatory properties to Notch signalling that exhibit integrative digital behaviours during tissue differentiation. Synopsis An optogenetic method to control endogenous Delta activity with light reveals that the Notch receptor acts as an integrator of analog signals that generates a digital switch‐like behaviour at the level of target gene expression during tissue differentiation. Optogenetic tagging of Delta at its endogenous locus allows precise inhibition of Notch signalling during Drosophila development using light. Photo‐activation induces rapid Delta clustering at the plasma membrane and Notch cis inhibition. Optogenetic inhibition of Delta reveals time‐integrated digital regulation of Notch signaling during tissue differentiation. Graphical Abstract An optogenetic method to control endogenous Delta activity with light reveals that the Notch receptor acts as an integrator of analog signals that generates a digital switch‐like behaviour at the level of target gene expression during tissue differentiation.