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Govorunova EG, Sineshchekov OA. Channelrhodopsins: From Phototaxis to Optogenetics. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1555-1570. [PMID: 38105024 DOI: 10.1134/s0006297923100115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 07/09/2023] [Accepted: 07/09/2023] [Indexed: 12/19/2023]
Abstract
Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that, channelrhodopsins are widely used in neuroscience and cardiology as instruments for optogenetic manipulation of the activity of excitable cells. Photocurrents generated by channelrhodopsins were first discovered in the cells of green algae in the 1970s. In this review we describe this discovery and discuss the current state of research in the field.
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DuBois DW, Murchison DA, Mahnke AH, Bang E, Winzer-Serhan U, Griffith WH, Souza KA. Maintenance of optogenetic channel rhodopsin (ChR2) function in aging mice: Implications for pharmacological studies of inhibitory synaptic transmission, quantal content, and calcium homeostasis. Neuropharmacology 2023:109651. [PMID: 37414332 DOI: 10.1016/j.neuropharm.2023.109651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/23/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023]
Abstract
Disruption of synaptic function is believed to represent a common pathway contributing to cognitive decline during aging. Optogenetics is a prodigious tool for studying relationships between function and synaptic circuitry but models utilizing viral vectors present limitations. Careful characterization of the functionality of channel rhodopsin in transgenic models is crucial for determining whether they can be used across aging. This includes verifying the light sensitivity of the protein and confirming its ability to generate action potentials in response to light stimulation. We combined in vitro optogenetic methodology and a reduced synaptic preparation of acutely isolated neurons to determine if the ChR2(H134R)-eYFP vGAT mouse model is well-suited for aging studies. We used neurons from young (2-6 mo), middle-aged (10-14 mo) and aged (17-25 mo) bacterial artificial chromosome (BAC) transgenic mouse line with stable expression of the channelrhodopsin-2 (ChR2) variant H134R in GABAergic cell populations. Cellular physiology and calcium dynamics were assessed in basal forebrain (BF) neurons using patch-clamp recording and fura-2 microfluorimetry, alongside 470 nm light stimulation of the transgenic ChR2 channel to characterize a wide array of physiological functions known to decline with age. We found ChR2 expression is functionally maintained across aging, while spontaneous and optically evoked inhibitory postsynaptic currents, and quantal content were decreased. Aged mice also showed an increase in intracellular calcium buffering. These results, which are on par with previous observations, demonstrate that the optogenetic vGAT BAC mouse model is well-suited for investigating age-related changes in calcium signaling and synaptic transmission.
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Affiliation(s)
- Dustin W DuBois
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA
| | - David A Murchison
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA
| | - Amanda H Mahnke
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA
| | - Eunyoung Bang
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA
| | - Ursula Winzer-Serhan
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA
| | - William H Griffith
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA
| | - Karienn A Souza
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, USA.
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Abstract
Research on type 1 rhodopsins spans now a history of 50 years. Originally, just archaeal ion pumps and sensors have been discovered. However, with modern genetic techniques and gene sequencing tools, more and more proteins were identified in all kingdoms of life. Spectroscopic and other biophysical studies revealed quite diverse functions. Ion pumps, sensors, and channels are imprinted in the same seven-helix transmembrane protein scaffold carrying a retinal prosthetic group. In this review, molecular biology methods are described, which enabled the elucidation of their function and structure leading to optogenetic applications.
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Affiliation(s)
- Martin Engelhard
- Department Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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Discovery of a microbial rhodopsin that is the most stable in extreme environments. iScience 2021; 24:102620. [PMID: 34151231 PMCID: PMC8188555 DOI: 10.1016/j.isci.2021.102620] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/28/2021] [Accepted: 05/19/2021] [Indexed: 12/18/2022] Open
Abstract
Microbial rhodopsin is a retinal protein that functions as an ion pump, channel, and sensory transducer, as well as a light sensor, as in biosensors and biochips. Tara76 rhodopsin is a typical proton-pumping rhodopsin that exhibits strong stability against extreme pH, detergent, temperature, salt stress, and dehydration stress and even under dual and triple conditions. Tara76 rhodopsin has a thermal stability approximately 20 times higher than that of thermal rhodopsin at 80°C and is even stable at 85°C. Tara76 rhodopsin is also stable at pH 0.02 to 13 and exhibits strong resistance in detergent, including Triton X-100 and SDS. We tested the current flow that electrical current flow across dried proteins on the paper at high temperatures using an electrode device, which was measured stably from 25°C up to 120°C. These properties suggest that this Tara76 rhodopsin is suitable for many applications in the fields of bioengineering and biotechnology.
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Luo X, He JY, Xu J, Hu SY, Mo BH, Shu QX, Chen C, Gong YZ, Zhao XL, Xie GF, Yu ST. Vascular NRP2 triggers PNET angiogenesis by activating the SSH1-cofilin axis. Cell Biosci 2020; 10:113. [PMID: 32983407 PMCID: PMC7509939 DOI: 10.1186/s13578-020-00472-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/08/2020] [Indexed: 12/12/2022] Open
Abstract
Background Angiogenesis is a critical step in the growth of pancreatic neuroendocrine tumors (PNETs) and may be a selective target for PNET therapy. However, PNETs are robustly resistant to current anti-angiogenic therapies that primarily target the VEGFR pathway. Thus, the mechanism of PNET angiogenesis urgently needs to be clarified. Methods Dataset analysis was used to identify angiogenesis-related genes in PNETs. Immunohistochemistry was performed to determine the relationship among Neuropilin 2 (NRP2), VEGFR2 and CD31. Cell proliferation, wound-healing and tube formation assays were performed to clarify the function of NRP2 in angiogenesis. The mechanism involved in NRP2-induced angiogenesis was detected by constructing plasmids with mutant variants and performing Western blot, and immunofluorescence assays. A mouse model was used to evaluate the effect of the NRP2 antibody in vivo, and clinical data were collected from patient records to verify the association between NRP2 and patient prognosis. Results NRP2, a VEGFR2 co-receptor, was positively correlated with vascularity but not with VEGFR2 in PNET tissues. NRP2 promoted the migration of human umbilical vein endothelial cells (HUVECs) cultured in the presence of conditioned medium PNET cells via a VEGF/VEGFR2-independent pathway. Moreover, NRP2 induced F-actin polymerization by activating the actin-binding protein cofilin. Cofilin phosphatase slingshot-1 (SSH1) was highly expressed in NRP2-activating cofilin, and silencing SSH1 ameliorated NRP2-activated HUVEC migration and F-actin polymerization. Furthermore, blocking NRP2 in vivo suppressed PNET angiogenesis and tumor growth. Finally, elevated NRP2 expression was associated with poor prognosis in PNET patients. Conclusion Vascular NRP2 promotes PNET angiogenesis by activating the SSH1/cofilin/actin axis. Our findings demonstrate that NRP2 is an important regulator of angiogenesis and a potential therapeutic target of anti-angiogenesis therapy for PNET.
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Affiliation(s)
- Xi Luo
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Jiang-Yi He
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Jie Xu
- Department of Urology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Shao-Yi Hu
- Nursing Division, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Bang-Hui Mo
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Qiu-Xia Shu
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Can Chen
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Yu-Zhu Gong
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Xiao-Long Zhao
- Department of Thoracic Surgery, Institute of Surgery Research, Daping Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Gan-Feng Xie
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
| | - Song-Tao Yu
- Department of Oncology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, People's Republic of China
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Light Stimulation Parameters Determine Neuron Dynamic Characteristics. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9183673] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Optogenetics is a recently developed technique that is widely used to study neuronal function. In optogenetic experiments, neurons encode opsins (channelrhodopsins, halorhodopsins or their derivatives) by means of viruses, plasmids or genetic modification (transgenic lines). Channelrhodopsin are light activated ion channels. Their expression in neurons allows light-dependent control of neuronal activity. The duration and frequency of light stimulation in optogenetic experiments is critical for stable, robust and reproducible experiments. In this study, we performed systematic analyses of these parameters using primary cultures of hippocampal neurons transfected with channelrhodopsin-2 (ChR2). The main goal of this work was to identify the optimal parameters of light stimulation that would result in stable neuronal activity during a repeated light pulse train. We demonstrated that the dependency of the photocurrent on the light pulse duration is described by a right-skewed bell-shaped curve, while the dependence on the stimulus intensity is close to linear. We established that a duration between 10–30 ms of stimulation was the minimal time necessary to achieve a full response. Obtained results will be useful in planning and interpretation of optogenetic experiments.
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Jáidar O, Carrillo-Reid L, Nakano Y, Lopez-Huerta VG, Hernandez-Cruz A, Bargas J, Garcia-Munoz M, Arbuthnott GW. Synchronized activation of striatal direct and indirect pathways underlies the behavior in unilateral dopamine-depleted mice. Eur J Neurosci 2019; 49:1512-1528. [PMID: 30633847 PMCID: PMC6767564 DOI: 10.1111/ejn.14344] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 12/17/2018] [Accepted: 12/25/2018] [Indexed: 11/27/2022]
Abstract
For more than three decades it has been known, that striatal neurons become hyperactive after the loss of dopamine input, but the involvement of dopamine (DA) D1‐ or D2‐receptor‐expressing neurons has only been demonstrated indirectly. By recording neuronal activity using fluorescent calcium indicators in D1 or D2 eGFP‐expressing mice, we showed that following dopamine depletion, both types of striatal output neurons are involved in the large increase in neuronal activity generating a characteristic cell assembly of particular neurons that dominate the pattern. When we expressed channelrhodopsin in all the output neurons, light activation in freely moving animals, caused turning like that following dopamine loss. However, if the light stimulation was patterned in pulses the animals circled in the other direction. To explore the neuronal participation during this stimulation we infected normal mice with channelrhodopsin and calcium indicator in striatal output neurons. In slices made from these animals, continuous light stimulation for 15 s induced many cells to be active together and a particular dominant group of neurons, whereas light in patterned pulses activated fewer cells in more variable groups. These results suggest that the simultaneous activity of a large dominant group of striatal output neurons is intimately associated with parkinsonian symptoms.
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Affiliation(s)
- Omar Jáidar
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Luis Carrillo-Reid
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Yoko Nakano
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | | | | | - José Bargas
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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Sato MP, Higuchi T, Nin F, Ogata G, Sawamura S, Yoshida T, Ota T, Hori K, Komune S, Uetsuka S, Choi S, Masuda M, Watabe T, Kanzaki S, Ogawa K, Inohara H, Sakamoto S, Takebayashi H, Doi K, Tanaka KF, Hibino H. Hearing Loss Controlled by Optogenetic Stimulation of Nonexcitable Nonglial Cells in the Cochlea of the Inner Ear. Front Mol Neurosci 2017; 10:300. [PMID: 29018325 PMCID: PMC5616010 DOI: 10.3389/fnmol.2017.00300] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 09/06/2017] [Indexed: 01/22/2023] Open
Abstract
Light-gated ion channels and transporters have been applied to a broad array of excitable cells including neurons, cardiac myocytes, skeletal muscle cells and pancreatic β-cells in an organism to clarify their physiological and pathological roles. Nonetheless, among nonexcitable cells, only glial cells have been studied in vivo by this approach. Here, by optogenetic stimulation of a different nonexcitable cell type in the cochlea of the inner ear, we induce and control hearing loss. To our knowledge, deafness animal models using optogenetics have not yet been established. Analysis of transgenic mice expressing channelrhodopsin-2 (ChR2) induced by an oligodendrocyte-specific promoter identified this channel in nonglial cells—melanocytes—of an epithelial-like tissue in the cochlea. The membrane potential of these cells underlies a highly positive potential in a K+-rich extracellular solution, endolymph; this electrical property is essential for hearing. Illumination of the cochlea to activate ChR2 and depolarize the melanocytes significantly impaired hearing within a few minutes, accompanied by a reduction in the endolymphatic potential. After cessation of the illumination, the hearing thresholds and potential returned to baseline during several minutes. These responses were replicable multiple times. ChR2 was also expressed in cochlear glial cells surrounding the neuronal components, but slight neural activation caused by the optical stimulation was unlikely to be involved in the hearing impairment. The acute-onset, reversible and repeatable phenotype, which is inaccessible to conventional gene-targeting and pharmacological approaches, seems to at least partially resemble the symptom in a population of patients with sensorineural hearing loss. Taken together, this mouse line may not only broaden applications of optogenetics but also contribute to the progress of translational research on deafness.
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Affiliation(s)
- Mitsuo P Sato
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan.,Department of Otolaryngology, Kindai University Faculty of MedicineOsaka, Japan
| | - Taiga Higuchi
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan
| | - Fumiaki Nin
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan.,Center for Transdisciplinary Research, Niigata UniversityNiigata, Japan
| | - Genki Ogata
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan.,Center for Transdisciplinary Research, Niigata UniversityNiigata, Japan
| | - Seishiro Sawamura
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan
| | - Takamasa Yoshida
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan.,Center for Transdisciplinary Research, Niigata UniversityNiigata, Japan.,Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu UniversityFukuoka, Japan
| | - Takeru Ota
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan
| | - Karin Hori
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan
| | - Shizuo Komune
- Division of Otolaryngology-Head and Neck Surgery, Yuaikai Oda HospitalSaga, Japan
| | - Satoru Uetsuka
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan.,Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka UniversityOsaka, Japan
| | - Samuel Choi
- Department of Electrical and Electronics Engineering, Niigata UniversityNiigata, Japan.,AMED-CREST, AMEDNiigata, Japan
| | - Masatsugu Masuda
- Department of Otolaryngology, Kyorin University School of MedicineTokyo, Japan
| | - Takahisa Watabe
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of MedicineTokyo, Japan
| | - Sho Kanzaki
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of MedicineTokyo, Japan
| | - Kaoru Ogawa
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of MedicineTokyo, Japan
| | - Hidenori Inohara
- Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka UniversityOsaka, Japan
| | - Shuichi Sakamoto
- Department of Mechanical and Production Engineering, Niigata UniversityNiigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata UniversityNiigata, Japan
| | - Katsumi Doi
- Department of Otolaryngology, Kindai University Faculty of MedicineOsaka, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, Keio University School of MedicineTokyo, Japan
| | - Hiroshi Hibino
- Department of Molecular Physiology, Niigata University School of MedicineNiigata, Japan.,Center for Transdisciplinary Research, Niigata UniversityNiigata, Japan.,AMED-CREST, AMEDNiigata, Japan
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Muñoz-Jiménez C, Ayuso C, Dobrzynska A, Torres-Mendéz A, Ruiz PDLC, Askjaer P. An Efficient FLP-Based Toolkit for Spatiotemporal Control of Gene Expression in Caenorhabditis elegans. Genetics 2017; 206:1763-1778. [PMID: 28646043 PMCID: PMC5560786 DOI: 10.1534/genetics.117.201012] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/19/2017] [Indexed: 02/07/2023] Open
Abstract
Site-specific recombinases are potent tools to regulate gene expression. In particular, the Cre (cyclization recombination) and FLP (flipase) enzymes are widely used to either activate or inactivate genes in a precise spatiotemporal manner. Both recombinases work efficiently in the popular model organism Caenorhabditis elegans, but their use in this nematode is still only sporadic. To increase the utility of the FLP system in C. elegans, we have generated a series of single-copy transgenic strains that stably express an optimized version of FLP in specific tissues or by heat induction. We show that recombination efficiencies reach 100% in several cell types, such as muscles, intestine, and serotonin-producing neurons. Moreover, we demonstrate that most promoters drive recombination exclusively in the expected tissues. As examples of the potentials of the FLP lines, we describe novel tools for induced cell ablation by expression of the PEEL-1 toxin and a versatile FLP-out cassette for generation of GFP-tagged conditional knockout alleles. Together with other recombinase-based reagents created by the C. elegans community, this toolkit increases the possibilities for detailed analyses of specific biological processes at developmental stages inside intact animals.
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Affiliation(s)
- Celia Muñoz-Jiménez
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Cristina Ayuso
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Agnieszka Dobrzynska
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Antonio Torres-Mendéz
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Patricia de la Cruz Ruiz
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Peter Askjaer
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
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