Optogenetic Approaches to Control Calcium Entry in Non-Excitable Cells

This chapter presents a brief overview of the design principles of Opto- calcium release–activated calcium (CRAC) constructs based on two different photoresponsive domains. The domain includes cryptochrome 2 and light–oxygen–voltage domain 2. The chapter illustrates how to use them to remotely control Ca2+ influx with at high spatiotemporal precision and subsequent nuclear translocation of a master transcriptional factor, the nuclear factor of activated T cells, to fine-tune nuclear factor of activated T cells-dependent gene expression and control the function of immune cells. The development of Opto-calcium release–activated calcium tools enables remote and convenient manipulation of intracellular calcium signals in non-excitable cells at an unprecedented spatiotemporal resolution. Light source commonly used for green fluorescent protein excitation in fluorescence microscopy can also be repurposed to activate Opto-CRAC and induce calcium entry. The Opto-CRAC tool is among the smallest optogenetic tools and is thus compatible with viral vectors used for in vivo gene delivery.