Developmental Genes Regulated by Optogenetic Signals in Drosophila and Analysis of Developmental Disorders in the United States

Abstract

MAPK (ERK) signaling is a conserved developmental pathway that is initiated upon a ligand binding to a receptor tyrosine kinase, which results in a cascade of protein interactions that culminates in changes in gene expression. Ectopic ERK activity has been implicated in diseases such as cancer and developmental disorders. However, much remains unknown regarding ERK signaling dynamics and how different levels of activation lead to normal or abnormal outcomes. Optogenetics provide an effective approach to understanding those dynamics by allowing perturbation of signaling pathways using specific wavelengths of light. We combined photoswitchable MEK, psMEKE203K, paired with a different Capicua-dependent MS2 reporter systems in Drosophila embryos to observe the transcriptional responses of ERK signaling. psMEKE203K causes high lethality in activating light and low lethality under inactivating light. Live monitoring of transcription and quantitative measurements show multiple transcriptional bursts under continuous ERK-activation and rapid response of Cic in establishing repression once ERK was inactivated. These findings demonstrate that psMEKE203K is an effective tool for precise control of the ERK pathway and that the response to ERK signaling is almost immediate. Future research can study the precise mechanism that allows this rapid response and apply this tool to other developmental pathways along with the broader workings of developmental disorders.