Curated Optogenetic Publication Database

Abstract: Temporal regulation of cyclic adenosine monophosphate (cAMP) using photoactivated adenylyl cyclase (bPAC) is critical in research; however, commercial optogenetic systems are costly. Here, we present a protocol for optogenetic control of cAMP in human telencephalic organoids using an easy-to-build Arduino-driven light-emitting diode (LED) stimulation system. We describe steps for assembling the system, writing code for LED regulation, and preparing induced pluripotent stem (iPS) cells for optogenetic experiments. We then detail procedures for optogenetic activation of cAMP to control cell-fate decisions. For complete information on the generation and use of this protocol, please refer to Shimada et al.1.

Abstract: Neural stem/progenitor cells (NPCs) have primary cilia, which are critical organelles for Sonic hedgehog signaling. However, little is known about the components of primary cilia in NPCs and whether manipulating signaling in the cilia is sufficient to alter dorsal/ventral regional identity. Using a human telencephalic organoid model, we perform comprehensive proteomic profiling of NPC cilia and find enrichment in GTPase signaling. Deletion of the ciliary GTPase ARL13B reduces ciliary localization of GPR161, an orphan G protein-coupled receptor 161 that negatively regulates Sonic hedgehog, resulting in ventralization of NPCs. GPR161 deletion also induces ventralization. To investigate whether manipulation of ciliary signaling is sufficient to restore dorsal identity in this context, we optogenetically elevate ciliary cAMP, rescuing dorsal fate in GPR161 KO organoids. Furthermore, chemogenetic induction of GPR161 removal from cilia is sufficient to increase ventral NPCs. These data indicate that ciliary signaling functions as a critical switch regulating dorsal/ventral fate decisions.