In BioLuminescent OptoGenetics (BL-OG), molecular light drives an optogenetic sensor. LuMinOpsins (LMOs) are single molecules that tether the light producer (luciferase) and opsin. In LMO3, bioluminescent (BL) light drives VChR1 causing depolarization when coelenterazine (CTZ) is present. LMO3 has now been vetted in multiple cell types and contexts.
Systemic impact (chemogenetic) and specific control (optogenetic) in the same mouse: Study I
Bioluminescent light reports the timing of neuromodulation after injection: Study II
Choose the timing; fast optogenetic and multiple chemogenetic time courses: Study II
Long-term biocompatibility: Studies I-IV
Order LMO3s as pAAV plasmids from Addgene (114099, 114103, 114104, 114105)
Order native CTZ from Nanolight
The LMO3-floxed mouse is available at Jackson Laboratory (Stock Number: 034853)
Read more, including a step by step protocol, and download a materials list: Crespo EL, Björefeldt A, Prakash M, Hochgeschwender U. 2021. Bioluminescent optogenetics 2.0: harnessing bioluminescence to activate photosensory proteins in vitro and in vivo. J Vis Exp (174).
Toxicology screens commissioned by Prolume (ms in prep., H. Schmidt) did not reveal any toxicity concerns of CTZ, the luciferin we employ, consistent with our extensive experience with repeated administration of it in water-soluble form. Another FAQ is whether CTZ can reach brain targets. Multiple published studies and our ongoing work show that CTZ can access the brain (e.g., neocortex, Choroid Plexus) after peripheral injection.
Study I: Impacting Development with Chemogenetic LMO3 Activation, then Probing Changes in the Adult with Optogenetic Drive
Medendorp et al. 2021 drove pyramidal neurons expressing LMO3 by IP CTZ injection P4-P10. They then used direct optogenetic drive of LMO3 to test adult excitability in the same cells. Adult mice showed robust behavioral and physiological changes after developmental BL-OG treatment.
Study II: Bioluminescent Light from LMO3 Reports Chemogenetic Activation in the Choroid Plexus
Shipley et al. (in review) describes novel imaging and control tools for in vivo Choroid Plexus (ChP) study. LMO3 activation in ChP showed distinct time courses for different CTZ injection routes.
Study III: IPSC control by LMO3 Post-Stroke: Chemogenetic or Optogenetic Activation Drives Behavioral Recovery and Synaptic Enhancement
Yu et al. (2019 J Neurosci) expressed LMO3 in induced pluripotent stem cells (IPSCs) implanted in vivo post-stroke. Chemogenetic or optogenetic LMO3 activation improved behavioral and sensory responses in vivo, and enhanced peri-infarct synaptic plasticity.
Study IV: LMO3 Activation Drives Motor Recovery Following Spinal Cord Injury
Petersen et al. (2022) expressed LMO3 in the ventral cord below an impact injury. Driving LMO3 activation with repeated CTZ injections (10 days) significantly enhanced the long-term recovery of motor coordination/control of the lower limbs, as compared to vehicle control treatment of injured mice.
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