Curated Optogenetic Publication Database

Abstract: The small GTPase Ras plays an important role in intracellular signal transduction and functions as a molecular switch. In this study, we used a photoresponsive protein as the molecular regulatory device to photoregulate Ras GTPase activity. Photo zipper (PZ), a variant of the photoresponsive protein Aureochrome1 developed by Hisatomi et al. (1-9) was incorporated into the C-terminus of Ras as a fusion protein. The three constructs of the Ras-PZ fusion protein had spacers of different lengths between Ras and PZ. They were designed using an Escherichia coli expression system. The Ras-PZ fusion proteins exhibited photoisomerization upon blue light irradiation and in the dark. Ras-PZ dimerized upon light irradiation. Moreover, Ras GTPase activity, which is accelerated by the Ras regulators guanine nucleotide exchange factors and GTPase-activating proteins, is controlled by photoisomerization. It has been suggested that light-responsive proteins are applicable to the photoswitching of the enzymatic activity of small GTPases as photoregulatory molecular devices.

Abstract: In addition to biochemical and electrochemical signaling, cells also rely extensively on mechanical signaling to regulate their behavior. While a number of tools have been adapted from physics and engineering to manipulate cell mechanics, they typically require specialized equipment or lack spatiotemporal precision. Alternatively, a recent, more elegant approach is to use light itself to modulate the mechanical equilibrium inside the cell. This approach leverages the power of optogenetics, which can be controlled in a fully reversible manner in both time and space, to tune RhoA signaling, the master regulator of cellular contractility. We review here the fundamentals of this approach, including illustrating the tunability and flexibility that optogenetics offers, and demonstrate how this tool can be used to modulate both internal cytoskeletal flows and contractile force generation. Together these features highlight the advantages that optogenetics offers for investigating mechanical interactions in cells.

Abstract: The nucleus is a very complex organelle present in eukaryotic cells. Having the crucial task to safeguard, organize and manage the genetic information, it must tightly control its molecular constituents, its shape and its internal architecture at any given time. Despite our vast knowledge of nuclear cell biology, much is yet to be unraveled. For instance, only recently we came to appreciate the existence of a dynamic nuclear cytoskeleton made of actin filaments that regulates processes such as gene expression, DNA repair and nuclear expansion. This suggests further exciting discoveries ahead of us. Modern cell biologists embrace a new methodology relying on precise perturbations of cellular processes that require a reversible, highly spatially-confinable, rapid, inexpensive and tunable external stimulus: light. In this review, we discuss how optogenetics, the state-of-the-art technology that uses genetically-encoded light-sensitive proteins to steer biological processes, can be adopted to specifically investigate nuclear cell biology.