Hochgeschwender Research -  Bioluminescent Optogenetics

The natural world supplies us with a vast contingent of light-sensing molecules, photoreceptors, from across the phylogenetic spectrum that are activated by sunlight. 

Nature also supplies us with light-emitting molecules, luciferases, enzymes that oxidize small molecule luciferins thereby emitting "biological light" or bioluminescence.

The research in our laboratory focuses on combining genetically encoded light emitters and light sensors for the bioluminescent activation of photoreceptors, BioLuminescent OptoGenetics (BL-OG). Bioluminescence can be harnessed to activate a wide range of light-controllable molecules for use within and across cells.

Bioluminescence Driving Opsins

Opsins, light-responsive ion conducting channels or pumps, are employed for genetically targeted modulation of a cell’s membrane potential. By tethering the luciferase to the opsin in a luminescent opsin, or luminopsin (LMO), opsins can be activated by bioluminescent light emitted when the luciferase oxidizes its substrate luciferin. As the option for activation by standard optogenetic light sources, i.e. LEDs, is maintained, LMOs enable bimodal (chemogenetic and optogenetic) activation.

^{Tool Development (examples):
Slaviero AN, Gorantla N, Simkins J, Crespo EL, Ikefuama EC, Tree MO, et al. Engineering luminopsins with improved coupling efficiencies. Neurophotonics. 2024;11(2):24208.
Berglund K, Clissold K, Li HE, Wen L, Park SY, Gleixner J, et al. Luminopsins integrate opto- and chemogenetics by using physical and biological light sources for opsin activation. Proc Natl Acad Sci U S A. 2016;113(3):E358–67.}

^{Applications (examples):
Ikefuama EC, Slaviero AN, Silvagnoli AD, Crespo EL, Schalau R, Gott M, et al. Presymptomatic Targeted Circuit Manipulation for Ameliorating Huntington’s Disease Pathogenesis. iScience. 2025;28(3):112022.
Petersen ED, Sharkey ED, Pal A, Shafau LO, Zenchak-Petersen J, Peña AJ, et al. Restoring Function After Severe Spinal Cord Injury Through BioLuminescent-OptoGenetics. Front Neurol. 2022;12:792643.
Medendorp WE, Bjorefeldt A, Crespo EL, Prakash M, Pal A, Waddell ML, et al. Selective postnatal excitation of neocortical pyramidal neurons results in distinctive behavioral and circuit deficits in adulthood. iScience. 2021;24(3):102157}

Bioluminescence Driving Non-Opsin Photoreceptors

Opsins are but a small part of the vast pool of photoreceptors, proteins that contain light-sensing domains Extension of the BL-OG approach to these non-opsin photoreceptors enables manipulation of a multitude of biological processes in cells from transcription to cell death, across temporal and spatial scales. In the example below bioluminescence enables dimerization of the light-sensing transcription factor EL222 and initiation of transcription. In principle, any photosensory protein can be combined with a luciferase for bioluminescent optogenetic control.

^{Crespo EL, Bjorefeldt A, Prakash M, Hochgeschwender U. Bioluminescent Optogenetics 2.0: Harnessing Bioluminescence to Activate Photosensory Proteins In Vitro and In Vivo. J Vis Exp. 2021;(174). doi: 10.3791/62850.}

Bioluminescence for Cell-to-Cell Communication

Bioluminescence-based communication between cells involves the generation of a light signal in one cell and its reception and translation into a response in another cell. We have realized this in “Interluminescence” to control synaptic transmission between neurons. Luciferase-generated bioluminescence emitted from a presynaptic neuron is used for activation of optogenetic elements in a postsynaptic neuron across the synaptic cleft. Two distinct versions of Interluminescence have been developed. For activity dependent Act-Int, luciferases targeted to synaptic vesicles are released upon firing of presynaptic neurons, while for activity-independent Persist-Int the luciferase is tethered to the membrane of presynaptic neurons.

^{Slaviero AN, Prakash M, Bell E, Schumaker R, Crespo EL, Tree MO, et al. Control of Synaptic Communication through Molecularly Engineered Bioluminescence Light Emission and Sensing. bioRxiv. 2025; 2025.10.27.684942.
Prakash M, Murphy J, St Laurent R, Friedman N, Crespo EL, Bjorefeldt A, et al. Selective control of synaptically-connected circuit elements by all-optical synapses. Commun Biol. 2022;5(1)}

Bioluminescence for Integration of Cellular Processes

Bioluminescence can be used for integrating intracellular activity states with user-defined changes in cellular function. Combining bioluminescent sensors, split luciferases whose light emission is dependent on the availability of an intracellular agent, with light-dependent actuators creates a Bioluminescent Activity Dependent (BLADe) platform for converting biochemical signals within cells into photoreceptor activation and downstream cellular outcomes. The luciferase can be split by different sensing domains, providing a general mechanism for cells to detect their own biochemical state and then drive discrete user-defined outcomes.

^{Crespo E L, Pal, A, Prakash M , Silvagnoli AD, Zaidi Z, Gomez-Ramirez M, et al. A Bioluminescent Activity Dependent (BLADe) Platform for Converting Neuronal Activity to Photoreceptor Activation. bioRxiv. 2025;2023.06.25.546469.}