1.
Using light to control signaling cascades in live neurons.
Abstract:
Understanding the complexity of neuronal biology requires the manipulation of cellular processes with high specificity and spatio-temporal precision. The recent development of synthetic photo-activatable proteins designed using the light-oxygen-voltage and phytochrome domains provides a new set of tools for genetically targeted optical control of cell signaling. Their modular design, functional diversity, precisely controlled activity and in vivo applicability offer many advantages for investigating neuronal function. Although designing these proteins is still a considerable challenge, future advances in rational protein design and a deeper understanding of their photoactivation mechanisms will allow the development of the next generation of optogenetic techniques.
2.
Induction of protein-protein interactions in live cells using light.
Abstract:
Protein-protein interactions are essential for many cellular processes. We have developed a technology called light-activated dimerization (LAD) to artificially induce protein hetero- and homodimerization in live cells using light. Using the FKF1 and GIGANTEA (GI) proteins of Arabidopsis thaliana, we have generated protein tags whose interaction is controlled by blue light. We demonstrated the utility of this system with LAD constructs that can recruit the small G-protein Rac1 to the plasma membrane and induce the local formation of lamellipodia in response to focal illumination. We also generated a light-activated transcription factor by fusing domains of GI and FKF1 to the DNA binding domain of Gal4 and the transactivation domain of VP16, respectively, showing that this technology is easily adapted to other systems. These studies set the stage for the development of light-regulated signaling molecules for controlling receptor activation, synapse formation and other signaling events in organisms.
