Optogenetic Application to Investigating Cell Behavior and Neurological Disease

Abstract

Cells reside in a dynamic microenvironment that presents them with regulatory signals that vary in time, space, and amplitude. The cell, in turn, interprets these signals and accordingly initiates downstream processes including cell proliferation, differentiation, migration, and self-organization. Conventional approaches to perturb and investigate signaling pathways (e.g., agonist/antagonist addition, overexpression, silencing, knockouts) are often binary perturbations that do not offer precise control over signaling levels, and/or provide limited spatial or temporal control. In contrast, optogenetics leverages light-sensitive proteins to control cellular signaling dynamics and target gene expression and, by virtue of precise hardware control over illumination, offers the capacity to interrogate how spatiotemporally varying signals modulate gene regulatory networks and cellular behaviors. Recent studies have employed various optogenetic systems in stem cell, embryonic, and somatic cell patterning studies, which have addressed fundamental questions of how cell-cell communication, subcellular protein localization, and signal integration affect cell fate. Other efforts have explored how alteration of signaling dynamics may contribute to neurological diseases and have in the process created physiologically relevant models that could inform new therapeutic strategies. In this review, we focus on emerging applications within the expanding field of optogenetics to study gene regulation, cell signaling, neurodevelopment, and neurological disorders, and we comment on current limitations and future directions for the growth of the field.

Keywords: cell signaling; gene regulation; neuroscience; optogenetics; spatiotemporal.

Figure 1

Representative schematics of four major optogenetic-based gene regulations using different systems (created with Biorender). (A,B) Light-induced uncaging of affinity domains (positive pMag) and (negative nMag) results in dimerization of attached domains and reassembly of (A) functional Cas9 for indel mutation and (B) split Cre recombinase for DNA recombination. (C) Upon light-induction, the Jα helix unfolds from LOV2 core to uncage a fused protein (PAH1, RILPN313) that inhibits the binding and activity of targeted transcription factor (REST). (D) Cry2 clusters an attached protein (LRP6c) in response to light that activates the downstream target genes, e.g., Wnt signaling.