Optogenetic Control of Nucleocytoplasmic Protein Transport

Multiphoton intravital microscopy of rodents

Tissues are heterogeneous with respect to cellular and non-cellular components and in the dynamic interactions between these elements. To study the behaviour and fate of individual cells in these complex tissues, intravital microscopy (IVM) techniques such as multiphoton microscopy have been developed to visualize intact and live tissues at cellular and subcellular resolution. IVM experiments have revealed unique insights into the dynamic interplay between different cell types and their local environment, and how this drives morphogenesis and homeostasis of tissues, inflammation and immune responses, and the development of various diseases. This Primer introduces researchers to IVM technologies, with a focus on multiphoton microscopy of rodents, and discusses challenges, solutions and practical tips on how to perform IVM. To illustrate the unique potential of IVM, several examples of results are highlighted. Finally, we discuss data reproducibility and how to handle big imaging data sets.

What sugar does to your pores

FG-repeat nucleoporins at the center of the nuclear pore complex (NPC) are highly modified with O-GlcNAc. In this issue, Yoo and Mitchison (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202010141) use optogenetic probes to show that O-GlcNAc enhances permeability of the NPC, accelerating transport in both directions.

Optogenetic Tools for Manipulating Protein Subcellular Localization and Intracellular Signaling at Organelle Contact Sites

Intracellular signaling processes are frequently based on direct interactions between proteins and organelles. A fundamental strategy to elucidate the physiological significance of such interactions is to utilize optical dimerization tools. These tools are based on the use of small proteins or domains that interact with each other upon light illumination. Optical dimerizers are particularly suitable for reproducing and interrogating a given protein-protein interaction and for investigating a protein's intracellular role in a spatially and temporally precise manner. Described in this article are genetic engineering strategies for the generation of modular light-activatable protein dimerization units and instructions for the preparation of optogenetic applications in mammalian cells. Detailed protocols are provided for the use of light-tunable switches to regulate protein recruitment to intracellular compartments, induce intracellular organellar membrane tethering, and reconstitute protein function using enhanced Magnets (eMags), a recently engineered optical dimerization system. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Genetic engineering strategy for the generation of modular light-activated protein dimerization units Support Protocol 1: Molecular cloning Basic Protocol 2: Cell culture and transfection Support Protocol 2: Production of dark containers for optogenetic samples Basic Protocol 3: Confocal microscopy and light-dependent activation of the dimerization system Alternate Protocol 1: Protein recruitment to intracellular compartments Alternate Protocol 2: Induction of organelles' membrane tethering Alternate Protocol 3: Optogenetic reconstitution of protein function Basic Protocol 4: Image analysis Support Protocol 3: Analysis of apparent on- and off-kinetics Support Protocol 4: Analysis of changes in organelle overlap over time.