Cellular interactions underlie diverse physiological processes. Efforts to image and manipulate these interactions have provided key insights into how cellular networks maintain homeostasis, as well as influence disease pathophysiologies. However, many strategies provide only “snapshots” of interactions at static time points, limiting investigations into how contacts influence and modulate cellular behavior. Furthermore, many methods have historically relied on fluorescent proteins and small molecule fluorophores, which can be difficult to employ in thick tissues due to the need for an external source of excitation light. Thus, we need new strategies for long-term tracking of cell populations of interest post-contact. These strategies would ideally employ novel optical reporters emitting signals capable of penetrating thick tissues.
My work has leveraged bioluminescence, an alternative imaging approach, comprised of enzymes (luciferases) capable of oxidizing small molecules (luciferins) to produce photons of light chemically. Bioluminescence imaging (BLI) with luciferase-luciferin pairs has been used for decades to track biological processes over time, but a lack of sufficiently red-shifted probes has precluded their use in thick tissues. Bioluminescence has also garnered interest in recent years as a power source for driving optogenetic circuits. However, generalizable bioluminescent optogenetic toolsets remain elusive. Collectively, this dissertation aims to address these many voids via: 1) engineering strategies for long-term tracking of cellular contact, 2) developing novel, red-shifted luciferase-luciferin pairs, 3) investigating the mechanism of bioluminescence-mediated optogenetics, and 4) employing these strategies to studies of cellular networks. Collectively, my work sets the stage for new discoveries relevant to immune function, cancer biology, and a multitude of other processes driven by cellular interactions in vivo.