Temporal control of growth factor‐mediated signaling pathways during cell differentiation and Xenopus embryonic development

Abstract

Growth factor‐mediated signaling pathways regulate a wide‐spectrum of cellular functions such as survival, proliferation, differentiation, and apoptosis. Different growth factors typically trigger the activation of the same set of downstream signaling pathways which includes the mitogen activated protein kinase (MAPK), phosphoinositide 3‐kinase (PI3K)‐AKT, and phospholipase C (PLC) pathways Evidence suggests that precise spatiotemporal regulation of these signaling pathways is involved in generating diverse cellular outcomes. Although conventional genetic and pharmacological approaches have helped us understand different aspects of signaling pathways, a quantitative delineation of their signaling kinetics is pending due to a lack of tools that allow for precise temporal control of these pathways. Non‐neuronal optogenetics, an emerging technique that utilizes light to control intracellular signaling pathways, is a remarkable tool to help achieve this goal. Here, we introduce a bicistronic optogenetic system which we recently developed in our laboratory to achieve temporal control of the MAPK pathway. This tool uses the photoactivatable protein cryptochrome 2 (CRY2) and the N‐terminal domain of cryptochrome‐interacting basic‐helix‐loop‐helix (CIBN) from Arabidopsis thaliana. This novel system allows reversible, light‐mediated activation of the MAPK signaling pathway in intact mammalian cells as well as in developing Xenopus laevis embryos. In PC12 neuronal cells, light‐controlled, intermittent MAPK activity reveals a memory effect in light‐induced neurite outgrowth. In Xenopus embryos, developmental stage‐specific MAPK activation further reveals that this pathway can reprogram cell fate after a crucial time window when germ layers are specified. Our strategy can be generalized to control other kinase pathways with a similar activation mechanism. Results from our research will help resolve intracellular mechanisms of growth factor‐mediated signal transduction during cell differentiation and embryonic development.Support or Funding InformationKai Zhang, Department of Biochemistry, University of Illinois Urbana‐ChampaignThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.