Light is used in microscopy in countless ways—to illuminate a sample, excite a fluorophore, and signal the localization or dynamics of a protein. Light can also be used to manipulate cellular events through the use of “caged” compounds that become active after illumination by certain wavelengths of light. This technology gives biologists the ability to spatially and temporally control cellular events in order to understand them better. Recent advances in this technology use illumination of plant photoreceptors to control protein-protein interactions, but some cellular processes such as protein secretion have been difficult to manipulate. A recent paper describes the use of the plant photoreceptor UVR8 in the first light-triggered protein secretion system developed. Chen and colleagues have shown that the recently described UVR8 can conditionally sequester proteins bound for secretion in the ER, and then upon illumination with UV light releases these proteins to the plasma membrane. In the images above, a neuron before (left) and after (right) UV illumination with this UVR8 system shows the movement of proteins known to be secreted from the soma and dendritic processes (arrowheads), where the ER is distributed, and into the Golgi (arrow), a necessary step in protein secretion.
Chen, D., Gibson, E., & Kennedy, M. (2013). A light-triggered protein secretion system originally published in the Journal of Cell Biology, 201 (4), 631-640 DOI: 10.1083/jcb.201210119
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