Elsevier

Current Opinion in Biotechnology

Volume 47, October 2017, Pages 112-119
Current Opinion in Biotechnology

Synthetic biological approaches to optogenetically control cell signaling

https://doi.org/10.1016/j.copbio.2017.06.010Get rights and content

Highlights

  • Optogenetics uses light to control genetically encoded cell components.

  • It is a precise tool for systematically addressing complex biological questions.

  • It has a potential for applications in medicine, pharmacology and elsewhere.

  • The latest optogenetic systems move from single cells to in vivo applications.

Precise spatial and temporal control of cellular processes is in life sciences a highly sought-after capability. In the recent years, this goal has become progressively achievable through the field of optogenetics, which utilizes light as a non-invasive means to control genetically encoded light-responsive proteins. The latest optogenetic systems, such as those for control of subcellular localization or cellular decision-making and tissue morphogenesis provide us with insights to gain a deeper understanding of the cellular inner workings. Besides, they hold a potential for further development into biomedical applications, from in vitro optogenetics-assisted drug candidate screenings to light-controlled gene therapy and tissue engineering.

Introduction

Optogenetics provides the ability to gain light-control over genetically encoded cell components, and thereby ultimately over signaling pathways or biological processes. Contrary to chemically inducible systems, where spatiotemporal capabilities are limited by the diffusion and the half-life of inducing molecules, light provides an exquisite precision of control and thus opens unique possibilities to disentangle the principles that govern nature.

Originally, optogenetics has been implemented in neuroscience [1], where light-responsive ion channels serve for remote control of action potential and thereby neural networks. Over the years, the field has spread beyond this scope and nowadays also makes use of diverse light-responsive protein modules to mediate the control of various biological functions. This latter, synthetic biological aspect of optogenetics will be the theme of this short review. First, we briefly familiarize the reader with the commonly used light-responsive modules and then systematically present the currently available approaches for light-control of different cell parts, with a strong emphasis on the most recent advances. Afterwards, we concisely review the latest optogenetic applications both in cell culture and in vivo, outlining the trends and likely future perspectives of the field.

Section snippets

Toolbox of light-responsive switch modules

A vast spectrum of photoreceptor proteins and their light-dependent interaction partners can be found in nature. A few of them have been already adopted as light-inducible switch modules, which can be utilized as protein fusion domains to build light-controlled systems in both prokaryotic and eukaryotic hosts, including mammalian cell lines and animals. The switch modules function as reversible, light-inducible interaction partners, forming either heterodimers (UVR8/COP1, Cry2/CIB1, FKF1/GI,

Light-control of gene regulation

A broad range of optogenetic tools for light-controlled gene regulation in cells has been developed, targeting both the externally introduced and the endogenous genes. Typically, these tools are based on one of the following three design concepts: (i) an optogenetic two-hybrid system for light-controlled recruitment of a gene effector (most commonly a transcription factor), (ii) a light-controlled reconstitution of a split gene effector, or (iii) a light-controlled nuclear import of a gene

Optogenetics in cell biology

Altering signaling proteins by equipping them with light-sensing input modules allows us to systematically perturb and dissect intracellular signaling networks to reveal the mechanisms that underlie them and ultimately the cellular behavior.

Diverse protein receptors, including the members of different receptor tyrosine kinase (RTK) families [33, 34, 35] and an innate immune receptor DAI [36], as well as a plethora of downstream signaling components, such as GEFs [37, 38, 39•], small GTPases [27

Conclusions and future perspectives

Optogenetics has lately matured from mostly proof of concept tools and implementations to being an excellent means for answering biological questions that other research tools were not able to address. Specifically, optogenetic approaches provide a superb spatiotemporally resolved alternative to the chemically controlled systems and classic genetic manipulation techniques (e.g. knockout, mutation and overexpression).

While the current optogenetic applications in individual cells, addressing

References and recommended reading

Papers of particular interest, published within the period of review, have been highlighted as:

  • • of special interest

  • •• of outstanding interest

Acknowledgements

We would like to thank Matej Žnidarič for his help with the preparation of figures. This work was supported by the Excellence Initiative of the German Federal and State Governments (EXC-294-BIOSS).

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