Investigation of the Fog Signaling Pathway

Abstract

In the complex and dynamic environment of the early embryo, individual cells must first receive signals in order to initiate the process of tissue folding. These signals occur at specific locations and at exact times during the organism's developmental timeline. Here, we examine the secreted autocrine signaling protein Folded gastrulation (Fog) and its receptor the mesoderm-invagination signal transducer (Mist). In this thesis we set out to simultaneously control both Fog and Mist expression so that we could test whether their co-expression is sufficient for tissue contractility. We took two parallel approaches: directly inducing Fog and Mist expression using the GAL4-UAS system, and developing an optogenetic expression system so that their expression could be controlled more precisely in space. We find that while Fog and Mist are individually necessary to induce these cellular movements, their co-expression is not sufficient to reproduce the contractility driven by optogenetic Erk activation. The work presented here helps to define the roles of Fog and Mist in the early embryo and tests the efficacy of our first-generation Opto-GAL4 system.