Curated Optogenetic Publication Database

Abstract: The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein syntaxin mediates neuronal exocytosis and self-assembles into large clusters in the plasma membrane. The formation and function of these clusters, and whether they promote or inhibit synaptic-vesicle fusion, remain unclear. Here using optogenetic control of syntaxin clustering in vitro and in vivo, as a light-inducible gain-of-function assay, we show that light-enhanced clustering reduces both spontaneous and triggered vesicle fusion, and this impairs mouse hunting behavior. Cluster formation is induced by liquid-liquid phase separation (LLPS) of the SNARE domain of syntaxin. For the regulatory mechanism, Munc18, which is known to alter syntaxin conformation, acts to reduce LLPS for cluster formation, thereby promoting active syntaxin. These results suggest that exocytosis regulation involves LLPS-induced syntaxin clusters that serve as a syntaxin reservoir from which Munc18 captures syntaxin monomers to form a syntaxin-Munc18 complex, setting the stage for efficient fusion.

Abstract: In cancer cells, lipid droplets (LDs) establish extensive membrane contact sites (MCSs) with mitochondria to facilitate fatty acid transfer and sustain energy production, thus enabling cancer cell survival, in nutrient-deprived tumor microenvironments. However, effective strategies to disrupt these LD-mitochondria interactions remain unavailable. We engineered an optogenetic system to control LD intracellular organization through clustering. Upon blue light stimulation, the system induces LDs to undergo spatial reorganization and form clusters, thereby restricting LD accessibility by reducing the available surface area for mitochondrial interaction. Consequently, this clustering significantly diminishes the number of LD-mitochondria MCSs, suppresses fatty acid transport from LDs to mitochondria during starvation, and ultimately leads to cancer cell death in vitro and tumor growth inhibition in vivo. Collectively, our results demonstrate that optogenetically controlled LD clustering offers a novel approach to impede tumor progression by blocking nutrient flow from LDs to mitochondria.

Abstract: Nerve growth factor elicits signaling outcomes by interacting with both its high-affinity receptor, TrkA, and its low-affinity receptor, p75NTR. Although these two receptors can regulate distinct cellular outcomes, they both activate the extracellular-signal-regulated kinase pathway upon nerve growth factor stimulation. To delineate TrkA subcircuits in PC12 cell differentiation, we developed an optogenetic system whereby light was used to specifically activate TrkA signaling in the absence of nerve growth factor. By using tyrosine mutants of the optogenetic TrkA in combination with pathway-specific pharmacological inhibition, we find that Y490 and Y785 each contributes to PC12 cell differentiation through the extracellular-signal-regulated kinase pathway in an additive manner. Optogenetic activation of TrkA eliminates the confounding effect of p75NTR and other potential off-target effects of the ligand. This approach can be generalized for the mechanistic study of other receptor-mediated signaling pathways.