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Ji ZG, Wang H. ChR2 transgenic animals in peripheral sensory system: Sensing light as various sensations. Life Sci 2016; 150:95-102. [PMID: 26903290 DOI: 10.1016/j.lfs.2016.02.057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/31/2015] [Accepted: 02/13/2016] [Indexed: 12/28/2022]
Abstract
Since the introduction of Channelrhodopsin-2 (ChR2) to neuroscience, optogenetics technology was developed, making it possible to activate specific neurons or circuits with spatial and temporal precision. Various ChR2 transgenic animal models have been generated and are playing important roles in revealing the mechanisms of neural activities, mapping neural circuits, controlling the behaviors of animals as well as exploring new strategy for treating the neurological diseases in both central and peripheral nervous system. An animal including humans senses environments through Aristotle's five senses (sight, hearing, smell, taste and touch). Usually, each sense is associated with a kind of sensory organ (eyes, ears, nose, tongue and skin). Is it possible that one could hear light, smell light, taste light and touch light? When ChR2 is targeted to different peripheral sensory neurons by viral vectors or generating ChR2 transgenic animals, the animals can sense the light as various sensations such as hearing, touch, pain, smell and taste. In this review, we focus on ChR2 transgenic animals in the peripheral nervous system. Firstly the working principle of ChR2 as an optogenetic actuator is simply described. Then the current transgenic animal lines where ChR2 was expressed in peripheral sensory neurons are presented and the findings obtained by these animal models are reviewed.
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Affiliation(s)
- Zhi-Gang Ji
- The Department of Neurology, Baylor College of Medicine, Houston, TX, United States
| | - Hongxia Wang
- The Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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Ogren JI, Yi A, Mamaev S, Li H, Spudich JL, Rothschild KJ. Proton transfers in a channelrhodopsin-1 studied by Fourier transform infrared (FTIR) difference spectroscopy and site-directed mutagenesis. J Biol Chem 2015; 290:12719-30. [PMID: 25802337 DOI: 10.1074/jbc.m114.634840] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Indexed: 11/06/2022] Open
Abstract
Channelrhodopsin-1 from the alga Chlamydomonas augustae (CaChR1) is a low-efficiency light-activated cation channel that exhibits properties useful for optogenetic applications such as a slow light inactivation and a red-shifted visible absorption maximum as compared with the more extensively studied channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2). Previously, both resonance Raman and low-temperature FTIR difference spectroscopy revealed that unlike CrChR2, CaChR1 under our conditions exhibits an almost pure all-trans retinal composition in the unphotolyzed ground state and undergoes an all-trans to 13-cis isomerization during the primary phototransition typical of other microbial rhodopsins such as bacteriorhodopsin (BR). Here, we apply static and rapid-scan FTIR difference spectroscopy along with site-directed mutagenesis to characterize the proton transfer events occurring upon the formation of the long-lived conducting P2 (380) state of CaChR1. Assignment of carboxylic C=O stretch bands indicates that Asp-299 (homolog to Asp-212 in BR) becomes protonated and Asp-169 (homolog to Asp-85 in BR) undergoes a net change in hydrogen bonding relative to the unphotolyzed ground state of CaChR1. These data along with earlier FTIR measurements on the CaChR1 → P1 transition are consistent with a two-step proton relay mechanism that transfers a proton from Glu-169 to Asp-299 during the primary phototransition and from the Schiff base to Glu-169 during P2 (380) formation. The unusual charge neutrality of both Schiff base counterions in the P2 (380) conducting state suggests that these residues may function as part of a cation selective filter in the open channel state of CaChR1 as well as other low-efficiency ChRs.
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Affiliation(s)
- John I Ogren
- From the Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts 02215 and
| | - Adrian Yi
- From the Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts 02215 and
| | - Sergey Mamaev
- From the Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts 02215 and
| | - Hai Li
- the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, Texas 77030
| | - John L Spudich
- the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, Texas 77030
| | - Kenneth J Rothschild
- From the Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts 02215 and
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Ogren JI, Yi A, Mamaev S, Li H, Lugtenburg J, DeGrip WJ, Spudich JL, Rothschild KJ. Comparison of the structural changes occurring during the primary phototransition of two different channelrhodopsins from Chlamydomonas algae. Biochemistry 2014; 54:377-88. [PMID: 25469620 PMCID: PMC4303311 DOI: 10.1021/bi501243y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
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Channelrhodopsins
(ChRs) from green flagellate algae function as
light-gated ion channels when expressed heterologously in mammalian
cells. Considerable interest has focused on understanding the molecular
mechanisms of ChRs to bioengineer their properties for specific optogenetic
applications such as elucidating the function of specific neurons
in brain circuits. While most studies have used channelrhodopsin-2
from Chlamydomonas reinhardtii (CrChR2), in this work low-temperature Fourier transform infrared-difference
spectroscopy is applied to study the conformational changes occurring
during the primary phototransition of the red-shifted ChR1 from Chlamydomonas augustae (CaChR1). Substitution
with isotope-labeled retinals or the retinal analogue A2, site-directed
mutagenesis, hydrogen–deuterium exchange, and H218O exchange were used to assign bands to the retinal
chromophore, protein, and internal water molecules. The primary phototransition
of CaChR1 at 80 K involves, in contrast to that of CrChR2, almost exclusively an all-trans to 13-cis isomerization of the retinal chromophore,
as in the primary phototransition of bacteriorhodopsin (BR). In addition,
significant differences are found for structural changes of the protein
and internal water(s) compared to those of CrChR2,
including the response of several Asp/Glu residues to retinal isomerization.
A negative amide II band is identified in the retinal ethylenic stretch
region of CaChR1, which reflects along with amide
I bands alterations in protein backbone structure early in the photocycle.
A decrease in the hydrogen bond strength of a weakly hydrogen bonded
internal water is detected in both CaChR1 and CrChR2, but the bands are much broader in CrChR2, indicating a more heterogeneous environment. Mutations involving
residues Glu169 and Asp299 (homologues of the Asp85 and Asp212 Schiff
base counterions, respectively, in BR) lead to the conclusion that
Asp299 is protonated during P1 formation and suggest that these residues
interact through a strong hydrogen bond that facilitates the transfer
of a proton from Glu169.
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Affiliation(s)
- John I Ogren
- Molecular Biophysics Laboratory, Photonics Center, and Department of Physics, Boston University , Boston, Massachusetts 02215, United States
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Boada DM, Martin TJ, Peters CM, Hayashida K, Harris MH, Houle TT, Boyden ES, Eisenach JC, Ririe DG. Fast-conducting mechanoreceptors contribute to withdrawal behavior in normal and nerve injured rats. Pain 2014; 155:2646-2655. [PMID: 25267211 DOI: 10.1016/j.pain.2014.09.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/27/2014] [Accepted: 09/22/2014] [Indexed: 11/29/2022]
Abstract
Fast-conducting myelinated high-threshold mechanoreceptors (AHTMR) are largely thought to transmit acute nociception from the periphery. However, their roles in normal withdrawal and in nerve injury-induced hyperalgesia are less well accepted. Modulation of this subpopulation of peripheral neurons would help define their roles in withdrawal behaviors. The optically active proton pump, ArchT, was placed in an adeno-associated virus-type 8 viral vector with the CAG promoter and was administered by intrathecal injection resulting in expression in myelinated neurons. Optical inhibition of peripheral neurons at the soma and transcutaneously was possible in the neurons expressing ArchT, but not in neurons from control animals. Receptive field characteristics and electrophysiology determined that inhibition was neuronal subtype-specific with only AHTMR neurons being inhibited. One week after nerve injury the AHTMR are hyperexcitable, but can still be inhibited at the soma and transcutaneously. Withdrawal thresholds to mechanical stimuli in normal and in hyperalgesic nerve-injured animals also were increased by transcutaneous light to the affected hindpaw. This suggests that AHTMR neurons play a role not only in threshold-related withdrawal behavior in the normal animal, but also in sensitized states after nerve injury. This is the first time this subpopulation of neurons has been reversibly modulated to test their contribution to withdrawal-related behaviors before and after nerve injury. This technique may prove useful to define the role of selective neuronal populations in different pain states.
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Affiliation(s)
- Danilo M Boada
- Department of Anesthesiology, Wake Forest School of Medicine, Winston-Salem, NC, USA The Synthetic Neurobiology Group, Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA
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Abstract
Methods to control neural activity by light have been introduced to the field of neuroscience. During the last decade, several techniques have been established, including optogenetics, thermogenetics, and infrared neural stimulation. The techniques allow investigators to turn-on or turn-off neural activity. This review is an attempt to show the importance of the techniques for the auditory field and provide insight in the similarities, overlap, and differences of the techniques. Discussing the mechanism of each of the techniques will shed light on the abilities and challenges for each of the techniques. The field has been grown tremendously and a review cannot be complete. However, efforts are made to summarize the important points and to refer the reader to excellent papers and reviews to specific topics. This article is part of a Special Issue entitled .
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Affiliation(s)
- Claus-Peter Richter
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, 303 E. Chicago Ave, Searle 12-561, Chicago, IL 60611, USA; Dept. of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Tech E310, Evanston, IL 60208, USA; The Hugh Knowles Center, Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
| | - Xiaodong Tan
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, 303 E. Chicago Ave, Searle 12-561, Chicago, IL 60611, USA
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Lignani G, Ferrea E, Difato F, Amarù J, Ferroni E, Lugarà E, Espinoza S, Gainetdinov RR, Baldelli P, Benfenati F. Long-term optical stimulation of channelrhodopsin-expressing neurons to study network plasticity. Front Mol Neurosci 2013; 6:22. [PMID: 23970852 PMCID: PMC3747358 DOI: 10.3389/fnmol.2013.00022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 07/30/2013] [Indexed: 12/31/2022] Open
Abstract
Neuronal plasticity produces changes in excitability, synaptic transmission, and network architecture in response to external stimuli. Network adaptation to environmental conditions takes place in time scales ranging from few seconds to days, and modulates the entire network dynamics. To study the network response to defined long-term experimental protocols, we setup a system that combines optical and electrophysiological tools embedded in a cell incubator. Primary hippocampal neurons transduced with lentiviruses expressing channelrhodopsin-2/H134R were subjected to various photostimulation protocols in a time window in the order of days. To monitor the effects of light-induced gating of network activity, stimulated transduced neurons were simultaneously recorded using multi-electrode arrays (MEAs). The developed experimental model allows discerning short-term, long-lasting, and adaptive plasticity responses of the same neuronal network to distinct stimulation frequencies applied over different temporal windows.
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Affiliation(s)
- Gabriele Lignani
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genoa, Italy
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Yao JP, Hou WS, Yin ZQ. Optogenetics: a novel optical manipulation tool for medical investigation. Int J Ophthalmol 2012; 5:517-22. [PMID: 22937517 DOI: 10.3980/j.issn.2222-3959.2012.04.22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 07/25/2012] [Indexed: 11/02/2022] Open
Abstract
Optogenetics is a new and rapidly evolving gene and neuroengineering technology that allows optical control of specific populations of neurons without affecting other neurons in the brain at high temporal and spatial resolution. By heterologous expression of the light-sensitive membrane proteins, cell type-specific depolarization or hyperpolarization can be optically induced on a millisecond time scale. Optogenetics has the higher selectivity and specificity compared to traditional electrophysiological techniques and pharmaceutical methods. It has been a novel promising tool for medical research. Because of easy handling, high temporal and spatial precision, optogenetics has been applied to many aspects of nervous system research, such as tactual neural circuit, visual neural circuit, auditory neural circuit and olfactory neural circuit, as well as research of some neurological diseases. The review highlights the recent advances of optogenetics in medical study.
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Affiliation(s)
- Jun-Ping Yao
- College of Biology Engineering, Chongqing University, Chongqing 400044, China
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Striatal microcircuitry and movement disorders. Trends Neurosci 2012; 35:557-64. [PMID: 22858522 DOI: 10.1016/j.tins.2012.06.008] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/19/2012] [Accepted: 06/29/2012] [Indexed: 11/23/2022]
Abstract
The basal ganglia network serves to integrate information about context, actions, and outcomes to shape the behavior of an animal based on its past experience. Clinically, the basal ganglia receive the most attention for their role in movement disorders. Recent advances in technology have opened new avenues of research into the structure and function of basal ganglia circuits. One emerging theme is the importance of GABAergic interneurons in coordinating and regulating network function. Here, we discuss evidence that changes in striatal GABAergic microcircuits contribute to basal ganglia dysfunction in several movement disorders. Because interneurons are genetically and neurochemically unique from striatal projection neurons, they may provide promising therapeutic targets for the treatment of a variety of striatal-based disorders.
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Hou SY, Govorunova EG, Ntefidou M, Lane CE, Spudich EN, Sineshchekov OA, Spudich JL. Diversity of Chlamydomonas channelrhodopsins. Photochem Photobiol 2012; 88:119-28. [PMID: 22044280 PMCID: PMC3253254 DOI: 10.1111/j.1751-1097.2011.01027.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Channelrhodopsins act as photoreceptors for control of motility behavior in flagellates and are widely used as genetically targeted tools to optically manipulate the membrane potential of specific cell populations ("optogenetics"). The first two channelrhodopsins were obtained from the model organism Chlamydomonas reinhardtii (CrChR1 and CrChR2). By homology cloning we identified three new channelrhodopsin sequences from the same genus, CaChR1, CyChR1 and CraChR2, from C. augustae, C. yellowstonensis and C. raudensis, respectively. CaChR1 and CyChR1 were functionally expressed in HEK293 cells, where they acted as light-gated ion channels similar to CrChR1. However, both, which are similar to each other, differed from CrChR1 in current kinetics, inactivation, light intensity dependence, spectral sensitivity and dependence on the external pH. These results show that extensive channelrhodopsin diversity exists even within the same genus, Chlamydomonas. The maximal spectral sensitivity of CaChR1 was at 520 nm at pH 7.4, about 40 nm redshifted as compared to that of CrChR1 under the same conditions. CaChR1 was successfully expressed in Pichia pastoris and exhibited an absorption spectrum identical to the action spectrum of CaChR1-generated photocurrents. The redshifted spectra and the lack of fast inactivation in CaChR1- and CyChR1-generated currents are features desirable for optogenetics applications.
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Affiliation(s)
- Sing-Yi Hou
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
| | - Elena G. Govorunova
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
| | - Maria Ntefidou
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
| | - C. Elizabeth Lane
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
| | - Elena N. Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
| | - Oleg A. Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
| | - John L. Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston TX 77030, USA
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