Bioluminescent Optogenetics Lab Research
Bioluminescent Optogenetics: Technology Development
BioLuminescent OptoGenetics (BL-OG) offers a highly modular and versatile approach for activating light-sensing molecules. The luciferases can be from different organisms (Gaussia, Renilla, Oplophorus) and can be improved upon by molecular engineering to provide higher light emission and to extend the wavelength of emitted light (blue to red-shifted). The optogenetic elements can be ion channels and pumps, applied to change membrane potential of cells and thus extremely useful in neuroscience, but in principle extend to any non-ion moving light-sensing element, including light-sensing transcription factors and recombinases. Optogenetic elements are matched with luciferases based on their activation wavelength and their sensitivity to light.
The combinations of light emitters and light sensors can vary in their molecular and cellular arrangement. The luciferase can be on the outside of the cell or inside, in the cytoplasm. Light emitter and sensor can be fused or co-expressed. The luciferase – opsin combination can be expressed in the same cell or the two components can be expressed in different cells.
Luminopsins (LMOs)
Luminopsins are fusion proteins of a light-emitting luciferase and a light-sensing opsin (channelrhodopsin or pump). Upon application of the luciferase substrate, coelenterazine, the luciferase emits light which activates the nearby opsin. Depending on the biophysical properties of the opsin, the neuron expressing the LMO will be activated or silenced.
When adapted to the experimental laboratory, photoreceptors are generally activated by lasers or LEDs. The opsins in LMOs retain the ability to be activated by physical light sources (optogenetically), while gaining the ability to be activated by the small molecule luciferin (chemogenetically).
We are continuously improving LMOs and expanding the combinations of luciferases and opsins.
Berglund K, Birkner E, Augustine GJ, Hochgeschwender U. Light-emitting Channelrhodopsins for combined optogenetic and chemical-genetic control of neurons. PLoS ONE 8: e59759, 2013. PMCID: PMC3609769
Berglund K, Clissold K, Li HE, Wen L, Park SY, Gleixner J, Klein ME, Lu D, Barter JW, Rossi MA, Augustine GJ, Yin HH, Hochgeschwender U. Luminopsins integrate physical and biological light sources for opsin activation in vivo. Proc Natl Acad Sci USA 113: E358-67, 2016. PMCID: PMC4725499
Interluminescence (Optical Synapse)
As in BL-OG both light emitter and light sensor are genetically encoded, they can be expressed in different cells. If they are expressed in synaptically connected neurons, this Interluminescence functions as a real-time optical synapse. We are characterizing the optical synapse in detail in patch-clamp recordings and are designing alternative strategies for activity-dependent and -independent release of the presynaptic luciferase. We are also utilizing Interluminescence for communication across other cell types.
Prakash M, Murphy J, St Laurent R, Friedman N, Crespo EL, Bjorefeldt A, Pal A, Bhagat Y, Kauer JA, Shaner NC, Lipscombe D, Moore CI, Hochgeschwender U. Selective Control of Synaptically-Connected Circuit Elements by All-Optical Synapses. Commun Biol 5:33, 2022. PMCID: PMC8752598
Bioluminescent Control of Non-Ion Moving Photosensors
Here we are using biological light, i.e. a light-generating protein (luciferase), to activate light-sensing proteins other than opsins (photoreceptors in general, including transcription factors and recombinases). Bioluminescence can induce protein unfolding and protein dimerization and these photoswitches can be employed for genetic activation and protein transformation.
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. Aug 4;(174), 2021. PMID: 34424228.
Bioluminescent Optogenetics: Applications
In addition to further advancing the concept of bioluminescence-driven optogenetics, our laboratory is applying the technology to address basic and preclinical neurobiological questions. We are exploring the potential use of the technology for the non-invasive treatment of Parkinson’s disease in mice and spinal cord injury in rats. Another focus is the relationship between brain development and the genesis of psychiatric disorders. We are taking advantage of BL-OG to study the role of neural activity during critical periods of postnatal brain development in forming adult circuitry and behavior.
Zenchak JR, Palmateer B, Dorka N, Brown TM, Wagner LM, Medendorp WE, Petersen ED, Prakash M, Hochgeschwender U. Bioluminescence-driven optogenetic activation of transplanted neural precursor cells improves motor deficits in a Parkinson's disease mouse model. J Neurosci Res. 98: 458-468, 2020. [Epub Mar 25, 2018] PMCID: PMC6157008
Medendorp WE, Bjorefeldt A, Crespo EL, Prakash M, Pal A, Waddell ML, Moore CI, Hochgeschwender U. Selective postnatal excitation of neocortical pyramidal neurons results in distinctive behavioral and circuit deficits in adulthood. iScience 24:102157, 2021. PMCID: PMC7907816
