UC San Diego

Our bodies are highly dynamic and the cells within our bodies must continuously sense their ever-changing environment. To respond to extracellular stimuli, signaling pathways are tightly regulated to enable proper cellular function. Spatiotemporal regulation of signal transduction is an emerging theme that enables specificity in signaling. Throughout this dissertation, the spatiotemporal regulation of the RhoA and cAMP/PKA signaling pathways was explored by using various novel tools such as fluorescence-based biosensors. In Chapter 2, we characterized receptor-mediated biphasic RhoA activation and found “memory”-like behaviors in RhoA activity. In Chapter 3, we discovered liquid-liquid phase separation of the PKA regulatory subunit RIα as a novel organizer of the cAMP/PKA pathway. We further showed that these biomolecular condensates enable cAMP compartmentation and suppress tumorigenic signaling. In Chapter 4, we engineered a suite of FRET-based biosensors to measure signaling dynamics around a protein of interest that is expressed at endogenous levels and applied these biosensors to unveil unique cAMP dynamics at clathrin plaques. Altogether, this dissertation showcases new tools for investigating signal transduction and the application of these tools to reveal novel modes of spatiotemporal regulation in intracellular signaling.