Tag Archives: Dimerizers

A modular single-construct tool for optical control of cell signaling

The study of cell signaling has revealed that cells can be particularly sensitive to spatiotemporal properties of the signaling dynamics. For instance, a cell can choose divergent fates (proliferation vs. differentiation, senescence vs. apoptosis, etc.) depending on the duration and strength of a protein signal. The development of fluorescent reporters has enabled us to observe these dynamics, but researchers still lack appropriate, general tools to perturb cells on the second- and minute-timescales on which signaling dynamics can occur.

Coupling light to protein activation may offer a powerful solution due to its fast, reversible, and highly tunable nature. In the March 2013 issue of Nature Methods, Bugaj, Kane, Schaffer and colleagues accomplish this by developing a method for light inducible homo-oligomerization of proteins. In this study, the authors report a genetically encodable, generalizable system that can activate multiple signaling proteins and networks in mammalian cells.

To do this, the authors leveraged the interesting ability of the Arabidopsis protein Cryptochrome 2 (Cry2) to form oligomers in response to blue light. To date, this clustering ability had only been shown in plant cells, but upon transfection into HEK 293Ts, the authors demonstrated that Cry2 can be clustered in mammalian cells as well (fig. … Continue reading

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A generalizable method for controlling protein activities with light

If we could control the activity of any intracellular protein of interest with light, it would revolutionize how we study biology and engineer gene- or cell-based therapies. For instance, optical protein control would allow testing of protein functions in cells with high spatiotemporal precision, so we can observe how protein activation at specific times and places affects downstream biochemical reactions and cellular behavior, without secondary effects from chronic or ubiquitous activation. Optical protein control would also allow four-dimensional regulation of cellular proliferation, survival, or differentiation in tissues or animals for basic research or therapy. Thus controlling a wide variety of proteins with light is one of the major long-term goals of optogenetics.

Meeting this challenge will require the development of easily generalizable methods for optical control of protein activity. Considerable efforts have been made to adapt natural light-responsive signaling proteins to regulate specific proteins of interest. In recent years, phytochrome-PIF, cryptochrome-CIB, and FKF-gigantea light-dependent interactions from plants have been adapted to control heterodimerization of proteins in mammalian cells. The LOV domain from phototropin has also been used to create single-chain photoactivatable proteins via light-modulated allosteric mechanisms. However, these methods have certain disadvantages. Light-controlled heterodimerization can not effectively control activities of … Continue reading

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