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Kumar D, Khan B, Okcay Y, Sis ÇÖ, Abdallah A, Murray F, Sharma A, Uemura M, Taliyan R, Heinbockel T, Rahman S, Goyal R. Dynamic endocannabinoid-mediated neuromodulation of retinal circadian circuitry. Ageing Res Rev 2024; 99:102401. [PMID: 38964508 DOI: 10.1016/j.arr.2024.102401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 06/05/2024] [Accepted: 06/28/2024] [Indexed: 07/06/2024]
Abstract
Circadian rhythms are biological rhythms that originate from the "master circadian clock," called the suprachiasmatic nucleus (SCN). SCN orchestrates the circadian rhythms using light as a chief zeitgeber, enabling humans to synchronize their daily physio-behavioral activities with the Earth's light-dark cycle. However, chronic/ irregular photic disturbances from the retina via the retinohypothalamic tract (RHT) can disrupt the amplitude and the expression of clock genes, such as the period circadian clock 2, causing circadian rhythm disruption (CRd) and associated neuropathologies. The present review discusses neuromodulation across the RHT originating from retinal photic inputs and modulation offered by endocannabinoids as a function of mitigation of the CRd and associated neuro-dysfunction. Literature indicates that cannabinoid agonists alleviate the SCN's ability to get entrained to light by modulating the activity of its chief neurotransmitter, i.e., γ-aminobutyric acid, thus preventing light-induced disruption of activity rhythms in laboratory animals. In the retina, endocannabinoid signaling modulates the overall gain of the retinal ganglion cells by regulating the membrane currents (Ca2+, K+, and Cl- channels) and glutamatergic neurotransmission of photoreceptors and bipolar cells. Additionally, endocannabinoids signalling also regulate the high-voltage-activated Ca2+ channels to mitigate the retinal ganglion cells and intrinsically photosensitive retinal ganglion cells-mediated glutamate release in the SCN, thus regulating the RHT-mediated light stimulation of SCN neurons to prevent excitotoxicity. As per the literature, cannabinoid receptors 1 and 2 are becoming newer targets in drug discovery paradigms, and the involvement of endocannabinoids in light-induced CRd through the RHT may possibly mitigate severe neuropathologies.
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Affiliation(s)
- Deepak Kumar
- Department of Neuropharmacology, School of Pharmaceutical Sciences, Shoolini University of Biotechnology and Management Sciences, Solan, HP 173229, India.
| | - Bareera Khan
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Solan, HP 173229, India
| | - Yagmur Okcay
- University of Health Sciences Gulhane Faculty of Pharmacy Department of Pharmacology, Turkey.
| | - Çağıl Önal Sis
- University of Health Sciences Gulhane Faculty of Pharmacy Department of Pharmacology, Turkey.
| | - Aya Abdallah
- Institute of Medical Science, University of Aberdeen, Aberdeen, Scotland.
| | - Fiona Murray
- Institute of Medical Science, University of Aberdeen, Aberdeen, Scotland.
| | - Ashish Sharma
- School of Medicine, Washington University, St. Louis, USA
| | - Maiko Uemura
- Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | - Rajeev Taliyan
- Department of Pharmacy, Birla Institute of Technology Science, Pilani, Rajasthan 333301, India.
| | - Thomas Heinbockel
- Howard University College of Medicine, Department of Anatomy, Washington, DC 20059, USA
| | - Shafiqur Rahman
- Department of Pharmaceutical Sciences, College of Pharmacy South Dakota State University, Brookings, SD, USA.
| | - Rohit Goyal
- Department of Neuropharmacology, School of Pharmaceutical Sciences, Shoolini University of Biotechnology and Management Sciences, Solan, HP 173229, India.
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Takahashi TM, Hirano A, Kanda T, Saito VM, Ashitomi H, Tanaka KZ, Yokoshiki Y, Masuda K, Yanagisawa M, Vogt KE, Tokuda T, Sakurai T. Optogenetic induction of hibernation-like state with modified human Opsin4 in mice. CELL REPORTS METHODS 2022; 2:100336. [PMID: 36452866 PMCID: PMC9701604 DOI: 10.1016/j.crmeth.2022.100336] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 09/01/2022] [Accepted: 10/19/2022] [Indexed: 05/28/2023]
Abstract
We recently determined that the excitatory manipulation of Qrfp-expressing neurons in the preoptic area of the hypothalamus (quiescence-inducing neurons [Q neurons]) induced a hibernation-like hypothermic/hypometabolic state (QIH) in mice. To control the QIH with a higher time resolution, we develop an optogenetic method using modified human opsin4 (OPN4; also known as melanopsin), a G protein-coupled-receptor-type blue-light photoreceptor. C-terminally truncated OPN4 (OPN4dC) stably and reproducibly induces QIH for at least 24 h by illumination with low-power light (3 μW, 473 nm laser) with high temporal resolution. The high sensitivity of OPN4dC allows us to transcranially stimulate Q neurons with blue-light-emitting diodes and non-invasively induce the QIH. OPN4dC-mediated QIH recapitulates the kinetics of the physiological changes observed in natural hibernation, revealing that Q neurons concurrently contribute to thermoregulation and cardiovascular function. This optogenetic method may facilitate identification of the neural mechanisms underlying long-term dormancy states such as sleep, daily torpor, and hibernation.
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Affiliation(s)
- Tohru M. Takahashi
- Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Arisa Hirano
- Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
- JST PRESTO, Japan
| | - Takeshi Kanda
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Viviane M. Saito
- Memory Research Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan
| | - Hiroto Ashitomi
- Memory Research Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan
| | - Kazumasa Z. Tanaka
- Memory Research Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan
| | - Yasufumi Yokoshiki
- Institute of Innovative Research (IIR), Tokyo Institute of Technology, Tokyo, Japan
| | - Kosaku Masuda
- Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Masashi Yanagisawa
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Kaspar E. Vogt
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Takashi Tokuda
- JST PRESTO, Japan
- Institute of Innovative Research (IIR), Tokyo Institute of Technology, Tokyo, Japan
| | - Takeshi Sakurai
- Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
- International Integrative Institute for Sleep medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
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Liebert A, Pang V, Bicknell B, McLachlan C, Mitrofanis J, Kiat H. A Perspective on the Potential of Opsins as an Integral Mechanism of Photobiomodulation: It's Not Just the Eyes. Photobiomodul Photomed Laser Surg 2022; 40:123-135. [PMID: 34935507 DOI: 10.1089/photob.2021.0106] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Objective: To investigate the potential relationship between opsins and photobiomodulation. Background: Opsins and other photoreceptors occur in all phyla and are important in light-activated signaling and organism homeostasis. In addition to the visual opsin systems of the retina (OPN1 and OPN2), there are several non-visual opsins found throughout the body tissues, including encephalopsin/panopsin (OPN3), melanopsin (OPN4), and neuropsin (OPN5), as well as other structures that have light-sensitive properties, such as enzymes, ion channels, particularly those located in cell membranes, lysosomes, and neuronal structures such as the nodes of Ranvier. The influence of these structures on exposure to light, including self-generated light within the body (autofluorescence), on circadian oscillators, and circadian and ultradian rhythms have become increasingly reported. The visual and non-visual phototransduction cascade originating from opsins and other structures has potential significant mechanistic effects on tissues and health. Methods: A PubMed and Google Scholar search was made using the search terms "photobiomodulation", "light", "neuron", "opsins", "neuropsin", "melanopsin", "encephalopsin", "rhodopsin", and "chromophore". Results: This review was examined the influence of neuropsin (also known as kallikrein 8), encephalopsin, and melanopsin specifically on ion channel function, and more broadly on the central and peripheral nervous systems. The relationship between opsins 3, 4, and 5 and photobiomodulation mechanisms was evaluated, along with a proposed role of photobiomodulation through opsins and light-sensitive organelles as potential alleviators of symptoms and accelerators of beneficial regenerative processes. The potential clinical implications of this in musculoskeletal conditions, wounds, and in the symptomatic management of neurodegenerative disease was also examined. Conclusions: Systematic research into the pleotropic therapeutic role of photobiomodulation, mediated through its action on opsins and other light-sensitive organelles may assist in the future execution of safe, low-risk precision medicine for a variety of chronic and complex disease conditions, and for health maintenance in aging.
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Affiliation(s)
- Ann Liebert
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, Australia.,Office of Governance and Research, San Hospital, Sydney, Australia
| | | | - Brian Bicknell
- Faculty of Health Science, Australian Catholic University, North Sydney, Australia
| | | | - John Mitrofanis
- Clinatec, Fonds de Dotation-CEA, Universitè Grenoble Alpes, Grenoble, France
| | - Hosen Kiat
- Department of Clinical Medicine, Macquarie University, Sydney, Australia.,Cardiac Health Institute, Sydney, Australia
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4
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Roecklein KA, Franzen PL, Wescott DL, Hasler BP, Miller MA, Donofry SD, DuPont CM, Gratzmiller SM, Drexler SP, Wood-Vasey WM, Gamlin PD. Melanopsin-driven pupil response in summer and winter in unipolar seasonal affective disorder. J Affect Disord 2021; 291:93-101. [PMID: 34029883 PMCID: PMC8693789 DOI: 10.1016/j.jad.2021.04.084] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/19/2021] [Accepted: 04/25/2021] [Indexed: 11/30/2022]
Abstract
A retinal subsensitivity to environmental light may trigger Seasonal Affective Disorder (SAD) under low wintertime light conditions. The main aim of this study was to assess the responses of melanopsin-containing retinal ganglion cells in participants (N= 65) diagnosed with unipolar SAD compared to controls with no history of depression. Participants attended a summer visit, a winter visit, or both. Retinal responses to light were measured using the post-illumination pupil response (PIPR) to assess melanopsin-driven responses in the non-visual light input pathway. Linear mixed-effects modeling was used to test a group*season interaction on the Net PIPR (red minus blue light response, percent baseline). We observed a significant group*season interaction such that the PIPR decreased from summer to winter significantly in the SAD group while not in the control group. The SAD group PIPR was significantly lower in winter compared to controls but did not differ between groups in summer. Only 60% of the participants underwent an eye health exam, although all participants reported no history of retinal pathology, and eye exam status was neither associated with outcome nor different between groups. This seasonal variation in melanopsin driven non-visual responses to light may be a risk factor for SAD, and further highlights individual differences in responses to light for direct or indirect effects of light on mood.
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Affiliation(s)
- Kathryn A. Roecklein
- Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,The Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania, USA.,Corresponding Author:Kathryn A. Roecklein, Ph.D. Associate Professor Department of Psychology, University of Pittsburgh 210 S. Bouquet Street Pittsburgh, PA 15206 (412) 624-4553
| | - Peter L. Franzen
- Department of Psychiatry, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Delainey L. Wescott
- Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Brant P. Hasler
- Department of Psychiatry, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Megan A. Miller
- Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Shannon D. Donofry
- Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Caitlin M. DuPont
- Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sarah M. Gratzmiller
- Department of Psychiatry, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Scott P. Drexler
- Department of Ophthalmology, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - W. Michael Wood-Vasey
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Paul D. Gamlin
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA
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5
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Krzysztynska-Kuleta OI, Olchawa MM, Sarna TJ. Melanopsin Signaling Pathway in HEK293 Cell Line with Stable Expression of Human Melanopsin: Possible Participation of Phospholipase C beta 4 and Diacylglycerol. Photochem Photobiol 2021; 97:1136-1144. [PMID: 33977551 DOI: 10.1111/php.13453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/07/2021] [Accepted: 05/06/2021] [Indexed: 12/17/2022]
Abstract
Melanopsin, a member of the G protein-coupled receptors family, is involved in non-image-forming functions including circadian rhythm, sleep regulation and pupil response. In spite of significant research efforts, the signaling cascade involving melanopsin photoactivation remains poorly characterized. Here, we analyzed the effects of photoactivation of melanopsin on phospholipase C (PLC) and diacylglycerol. As an in vitro model, HEK293 cells with stable expression of human melanopsin were used. Although both the PLCβ1 and PLCβ4 subtypes were activated by the cell exposure to blue light, only PLCβ4 appeared to play a significant role in the studied melanopsin signaling pathway. We have demonstrated, for the first time, that cells expressing human melanopsin and enriched with 11-cis-retinal exhibited significantly increased diacylglycerol level. To determine the role of phospholipase C and involvement of diacylglycerols, two approaches were employed: inhibition of the G protein and phospholipase C (using the BIM-46187 and U73122 inhibitors, respectively), and gene silencing using siRNA of PLCβ1 and PLCβ4 . While silencing the PLCβ4 gene and using U73122 inhibited the diacylglycerol and calcium ion responses, the FOS gene expression level was only partially reduced. These results may facilitate a better understanding of the role of phospholipase C and diacylglycerols in the melanopsin signaling pathway.
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Affiliation(s)
- Olga I Krzysztynska-Kuleta
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, 30-387, Poland
| | - Magdalena M Olchawa
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, 30-387, Poland
| | - Tadeusz J Sarna
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, 30-387, Poland
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6
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Upton BA, Díaz NM, Gordon SA, Van Gelder RN, Buhr ED, Lang RA. Evolutionary Constraint on Visual and Nonvisual Mammalian Opsins. J Biol Rhythms 2021; 36:109-126. [PMID: 33765865 PMCID: PMC8058843 DOI: 10.1177/0748730421999870] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Animals have evolved light-sensitive G protein-coupled receptors, known as opsins, to detect coherent and ambient light for visual and nonvisual functions. These opsins have evolved to satisfy the particular lighting niches of the organisms that express them. While many unique patterns of evolution have been identified in mammals for rod and cone opsins, far less is known about the atypical mammalian opsins. Using genomic data from over 400 mammalian species from 22 orders, unique patterns of evolution for each mammalian opsins were identified, including photoisomerases, RGR-opsin (RGR) and peropsin (RRH), as well as atypical opsins, encephalopsin (OPN3), melanopsin (OPN4), and neuropsin (OPN5). The results demonstrate that OPN5 and rhodopsin show extreme conservation across all mammalian lineages. The cone opsins, SWS1 and LWS, and the nonvisual opsins, OPN3 and RRH, demonstrate a moderate degree of sequence conservation relative to other opsins, with some instances of lineage-specific gene loss. Finally, the photoisomerase, RGR, and the best-studied atypical opsin, OPN4, have high sequence diversity within mammals. These conservation patterns are maintained in human populations. Importantly, all mammalian opsins retain key amino acid residues important for conjugation to retinal-based chromophores, permitting light sensitivity. These patterns of evolution are discussed along with known functions of each atypical opsin, such as in circadian or metabolic physiology, to provide insight into the observed patterns of evolutionary constraint.
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Affiliation(s)
- Brian A. Upton
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Center for Chronobiology, Division of Pediatric Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Molecular & Developmental Biology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Nicolás M. Díaz
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
| | - Shannon A. Gordon
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
| | - Russell N. Van Gelder
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
- Departments of Biological Structure and Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, Washington
| | - Ethan D. Buhr
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington
| | - Richard A. Lang
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Center for Chronobiology, Division of Pediatric Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
- Department of Ophthalmology, University of Cincinnati College of Medicine, Cincinnati, Ohio
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7
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Hellmer CB, Bohl JM, Hall LM, Koehler CC, Ichinose T. Dopaminergic Modulation of Signal Processing in a Subset of Retinal Bipolar Cells. Front Cell Neurosci 2020; 14:253. [PMID: 32922266 PMCID: PMC7456991 DOI: 10.3389/fncel.2020.00253] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/23/2020] [Indexed: 11/13/2022] Open
Abstract
The retina and the olfactory bulb are the gateways to the visual and olfactory systems, respectively, similarly using neural networks to initiate sensory signal processing. Sensory receptors receive signals that are transmitted to neural networks before projecting to primary cortices. These networks filter sensory signals based on their unique features and adjust their sensitivities by gain control systems. Interestingly, dopamine modulates sensory signal transduction in both systems. In the retina, dopamine adjusts the retinal network for daylight conditions (“light adaptation”). In the olfactory system, dopamine mediates lateral inhibition between the glomeruli, resulting in odorant signal decorrelation and discrimination. While dopamine is essential for signal discrimination in the olfactory system, it is not understood whether dopamine has similar roles in visual signal processing in the retina. To elucidate dopaminergic effects on visual processing, we conducted patch-clamp recording from second-order retinal bipolar cells, which exhibit multiple types that can convey different temporal features of light. We recorded excitatory postsynaptic potentials (EPSPs) evoked by various frequencies of sinusoidal light in the absence and presence of a dopamine receptor 1 (D1R) agonist or antagonist. Application of a D1R agonist, SKF-38393, shifted the peak temporal responses toward higher frequencies in a subset of bipolar cells. In contrast, a D1R antagonist, SCH-23390, reversed the effects of SKF on these types of bipolar cells. To examine the mechanism of dopaminergic modulation, we recorded voltage-gated currents, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, and low-voltage activated (LVA) Ca2+ channels. SKF modulated HCN and LVA currents, suggesting that these channels are the target of D1R signaling to modulate visual signaling in these bipolar cells. Taken together, we found that dopamine modulates the temporal tuning of a subset of retinal bipolar cells. Consequently, we determined that dopamine plays a role in visual signal processing, which is similar to its role in signal decorrelation in the olfactory bulb.
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Affiliation(s)
- Chase B Hellmer
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Jeremy M Bohl
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Leo M Hall
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Christina C Koehler
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Tomomi Ichinose
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
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8
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Valdez-Lopez JC, Petr ST, Donohue MP, Bailey RJ, Gebreeziabher M, Cameron EG, Wolf JB, Szalai VA, Robinson PR. The C-Terminus and Third Cytoplasmic Loop Cooperatively Activate Mouse Melanopsin Phototransduction. Biophys J 2020; 119:389-401. [PMID: 32621866 PMCID: PMC7376183 DOI: 10.1016/j.bpj.2020.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/28/2020] [Accepted: 06/10/2020] [Indexed: 11/30/2022] Open
Abstract
Melanopsin, an atypical vertebrate visual pigment, mediates non-image-forming light responses including circadian photoentrainment and pupillary light reflexes and contrast detection for image formation. Melanopsin-expressing intrinsically photosensitive retinal ganglion cells are characterized by sluggish activation and deactivation of their light responses. The molecular determinants of mouse melanopsin's deactivation have been characterized (i.e., C-terminal phosphorylation and β-arrestin binding), but a detailed analysis of melanopsin's activation is lacking. We propose that an extended third cytoplasmic loop is adjacent to the proximal C-terminal region of mouse melanopsin in the inactive conformation, which is stabilized by the ionic interaction of these two regions. This model is supported by site-directed spin labeling and electron paramagnetic resonance spectroscopy of melanopsin, the results of which suggests a high degree of steric freedom at the third cytoplasmic loop, which is increased upon C-terminus truncation, supporting the idea that these two regions are close in three-dimensional space in wild-type melanopsin. To test for a functionally critical C-terminal conformation, calcium imaging of melanopsin mutants including a proximal C-terminus truncation (at residue 365) and proline mutation of this proximal region (H377P, L380P, Y382P) delayed melanopsin's activation rate. Mutation of all potential phosphorylation sites, including a highly conserved tyrosine residue (Y382), into alanines also delayed the activation rate. A comparison of mouse melanopsin with armadillo melanopsin-which has substitutions of various potential phosphorylation sites and a substitution of the conserved tyrosine-indicates that substitution of these potential phosphorylation sites and the tyrosine residue result in dramatically slower activation kinetics, a finding that also supports the role of phosphorylation in signaling activation. We therefore propose that melanopsin's C-terminus is proximal to intracellular loop 3, and C-terminal phosphorylation permits the ionic interaction between these two regions, thus forming a stable structural conformation that is critical for initiating G-protein signaling.
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Affiliation(s)
- Juan C Valdez-Lopez
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland
| | - Stephen T Petr
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland
| | - Matthew P Donohue
- Center for Nanoscale and Technology, National Institutes of Standards and Technology, Gaithersburg, Maryland; Maryland NanoCenter, University of Maryland College Park, College Park, Maryland
| | - Robin J Bailey
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland
| | - Meheret Gebreeziabher
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland
| | - Evan G Cameron
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland
| | - Julia B Wolf
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland
| | - Veronika A Szalai
- Center for Nanoscale and Technology, National Institutes of Standards and Technology, Gaithersburg, Maryland
| | - Phyllis R Robinson
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland.
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9
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Duda M, Domagalik A, Orlowska-Feuer P, Krzysztynska-Kuleta O, Beldzik E, Smyk MK, Stachurska A, Oginska H, Jeczmien-Lazur JS, Fafrowicz M, Marek T, Lewandowski MH, Sarna T. Melanopsin: From a small molecule to brain functions. Neurosci Biobehav Rev 2020; 113:190-203. [DOI: 10.1016/j.neubiorev.2020.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 12/29/2022]
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10
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Hu H, Kang C, Hou X, Zhang Q, Meng Q, Jiang J, Hao W. Blue Light Deprivation Produces Depression-Like Responses in Mongolian Gerbils. Front Psychiatry 2020; 11:233. [PMID: 32322220 PMCID: PMC7156555 DOI: 10.3389/fpsyt.2020.00233] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/10/2020] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Depression is a leading cause of disability worldwide and is a major contributor to the overall global burden of disease, but its etiology is poorly understood. It has been reported that a disrupted biological rhythm, in terms of a shortened light duration and total darkness, can cause depression-like behaviors in animals. Blue light was reported to have an inhibitory effect on melatonin, which is considered an important clock rhythm biomarker. In the present study, we investigated the effects of blue light deprivation on depressive-like behaviors in gerbils and explored the underlying mechanisms. METHODS Gerbils were housed under white light with a filter to block the blue light or without a filter. The behaviors of the gerbils were observed. The biological rhythm, 5-HT, hypothalamic-pituitary-adrenal (HPA) axis and melanopsin pathway were analyzed. RESULTS We found that blue light deprivation (BLD) induced depression-like behavior in gerbils. Melatonin lost its rhythm, and corticosterone (CORT) levels decreased in the morning in the BLD group. Lower corticotropin-releasing hormone (CRH) in the hypothalamus and lower adrenocorticotropin hormone (ACTH)/CORT in serum were observed after BLD. Furthermore, 5-HT in the serum and brain were decreased after BLD. Additionally, BLD affected the blue light sensitivity protein melanopsin and its pathway, with downregulation of the proteins melanopsin, PKCα, and c-Fos and the mRNA levels of c-fos and trpc3 and upregulation of the protein p-PKCα. CONCLUSIONS Our findings indicated that BLD might produce depression-like behaviors in gerbils. Melatonin arrhythmicity, HPA axis abnormalities, 5-HT decreases and melanopsin pathway changes might be associated with the depression behavioral phenotype in gerbils.
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Affiliation(s)
- Hong Hu
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
| | - Chenping Kang
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
| | - Xiaohong Hou
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
| | - Qi Zhang
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
| | - Qinghe Meng
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
| | - Jianjun Jiang
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
| | - Weidong Hao
- Department of Toxicology, School of Public Health, Peking University, Beijing, China
- Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, China
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11
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Valdez-Lopez JC, Gulati S, Ortiz EA, Palczewski K, Robinson PR. Melanopsin Carboxy-terminus phosphorylation plasticity and bulk negative charge, not strict site specificity, achieves phototransduction deactivation. PLoS One 2020; 15:e0228121. [PMID: 32236094 PMCID: PMC7112210 DOI: 10.1371/journal.pone.0228121] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 03/06/2020] [Indexed: 11/19/2022] Open
Abstract
Melanopsin is a visual pigment expressed in a small subset of ganglion cells in the mammalian retina known as intrinsically photosensitive retinal ganglion cells (ipRGCs) and is implicated in regulating non-image forming functions such as circadian photoentrainment and pupil constriction and contrast sensitivity in image formation. Mouse melanopsin's Carboxy-terminus (C-terminus) possesses 38 serine and threonine residues, which can potentially serve as phosphorylation sites for a G-protein Receptor Kinase (GRK) and be involved in the deactivation of signal transduction. Previous studies suggest that S388, T389, S391, S392, S394, S395 on the proximal region of the C-terminus of mouse melanopsin are necessary for melanopsin deactivation. We expressed a series of mouse melanopsin C-terminal mutants in HEK293 cells and using calcium imaging, and we found that the necessary cluster of six serine and threonine residues, while being critical, are insufficient for proper melanopsin deactivation. Interestingly, the additional six serine and threonine residues adjacent to the required six sites, in either proximal or distal direction, are capable of restoring wild-type deactivation of melanopsin. These findings suggest an element of plasticity in the molecular basis of melanopsin phosphorylation and deactivation. In addition, C-terminal chimeric mutants and molecular modeling studies support the idea that the initial steps of deactivation and β-arrestin binding are centered around these critical phosphorylation sites (S388-S395). The degree of functional versatility described in this study, along with ipRGC biophysical heterogeneity and the possible use of multiple signal transduction cascades, might contribute to the diverse ipRGC light responses for use in non-image and image forming behaviors, even though all six sub types of ipRGCs express the same melanopsin gene OPN4.
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MESH Headings
- HEK293 Cells
- Humans
- Light Signal Transduction/physiology
- Models, Molecular
- Mutagenesis, Site-Directed
- Mutation
- Phosphorylation/physiology
- Protein Binding
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Rod Opsins/chemistry
- Rod Opsins/genetics
- Rod Opsins/metabolism
- Serine/genetics
- Serine/metabolism
- Threonine/genetics
- Threonine/metabolism
- beta-Arrestin 1/chemistry
- beta-Arrestin 1/metabolism
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Affiliation(s)
- Juan C. Valdez-Lopez
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, United States of America
| | - Sahil Gulati
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, California, United States of America
- Gatan Inc, Pleasanton, California, United States of America
| | - Elelbin A. Ortiz
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, United States of America
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, California, United States of America
| | - Phyllis R. Robinson
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, United States of America
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12
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Do MTH. Melanopsin and the Intrinsically Photosensitive Retinal Ganglion Cells: Biophysics to Behavior. Neuron 2019; 104:205-226. [PMID: 31647894 PMCID: PMC6944442 DOI: 10.1016/j.neuron.2019.07.016] [Citation(s) in RCA: 146] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/19/2019] [Accepted: 07/12/2019] [Indexed: 12/19/2022]
Abstract
The mammalian visual system encodes information over a remarkable breadth of spatiotemporal scales and light intensities. This performance originates with its complement of photoreceptors: the classic rods and cones, as well as the intrinsically photosensitive retinal ganglion cells (ipRGCs). IpRGCs capture light with a G-protein-coupled receptor called melanopsin, depolarize like photoreceptors of invertebrates such as Drosophila, discharge electrical spikes, and innervate dozens of brain areas to influence physiology, behavior, perception, and mood. Several visual responses rely on melanopsin to be sustained and maximal. Some require ipRGCs to occur at all. IpRGCs fulfill their roles using mechanisms that include an unusual conformation of the melanopsin protein, an extraordinarily slow phototransduction cascade, divisions of labor even among cells of a morphological type, and unorthodox configurations of circuitry. The study of ipRGCs has yielded insight into general topics that include photoreceptor evolution, cellular diversity, and the steps from biophysical mechanisms to behavior.
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Affiliation(s)
- Michael Tri H Do
- F.M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital and Harvard Medical School, Center for Life Science 12061, 3 Blackfan Circle, Boston, MA 02115, USA.
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13
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Lelle M, Otte M, Thon S, Bertinetti D, Herberg FW, Benndorf K. Chemical synthesis and biological activity of novel brominated 7-deazaadenosine-3',5'-cyclic monophosphate derivatives. Bioorg Med Chem 2019; 27:1704-1713. [PMID: 30879860 DOI: 10.1016/j.bmc.2019.03.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/09/2019] [Accepted: 03/11/2019] [Indexed: 11/19/2022]
Abstract
Synthetic derivatives of cyclic adenosine monophosphate, such as halogenated or other more hydrophobic analogs, are widely used compounds, to investigate diverse signal transduction pathways of eukaryotic cells. This inspired us to develop cyclic nucleotides, which exhibit chemical structures composed of brominated 7-deazaadenines and the phosphorylated ribosugar. The synthesized 8-bromo- and 7-bromo-7-deazaadenosine-3',5'-cyclic monophosphates rank among the most potent activators of cyclic nucleotide-regulated ion channels as well as cAMP-dependent protein kinase. Moreover, these substances bind tightly to exchange proteins directly activated by cAMP.
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Affiliation(s)
- Marco Lelle
- Institute of Physiology II, University Hospital Jena, Kollegiengasse 9, 07743 Jena, Germany
| | - Maik Otte
- Institute of Physiology II, University Hospital Jena, Kollegiengasse 9, 07743 Jena, Germany
| | - Susanne Thon
- Institute of Physiology II, University Hospital Jena, Kollegiengasse 9, 07743 Jena, Germany
| | - Daniela Bertinetti
- Department of Biochemistry, University of Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Friedrich W Herberg
- Department of Biochemistry, University of Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Klaus Benndorf
- Institute of Physiology II, University Hospital Jena, Kollegiengasse 9, 07743 Jena, Germany.
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14
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Stachurska A, Sarna T. Regulation of Melanopsin Signaling: Key Interactions of the Nonvisual Photopigment. Photochem Photobiol 2018; 95:83-94. [DOI: 10.1111/php.12995] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/26/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Anna Stachurska
- Labolatory of Imaging and Force Spectroscopy; Malopolska Centre of Biotechnology; Jagiellonian University; Krakow Poland
| | - Tadeusz Sarna
- Department of Biophysics; Faculty of Biochemistry, Biophysics and Biotechnology; Jagiellonian University; Krakow Poland
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15
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Mure LS, Hatori M, Zhu Q, Demas J, Kim IM, Nayak SK, Panda S. Melanopsin-Encoded Response Properties of Intrinsically Photosensitive Retinal Ganglion Cells. Neuron 2016; 90:1016-27. [PMID: 27181062 DOI: 10.1016/j.neuron.2016.04.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/17/2016] [Accepted: 04/06/2016] [Indexed: 11/16/2022]
Abstract
Melanopsin photopigment expressed in intrinsically photosensitive retinal ganglion cells (ipRGCs) plays a crucial role in the adaptation of mammals to their ambient light environment through both image-forming and non-image-forming visual responses. The ipRGCs are structurally and functionally distinct from classical rod/cone photoreceptors and have unique properties, including single-photon response, long response latency, photon integration over time, and slow deactivation. We discovered that amino acid sequence features of melanopsin protein contribute to the functional properties of the ipRGCs. Phosphorylation of a cluster of Ser/Thr residues in the C-terminal cytoplasmic region of melanopsin contributes to deactivation, which in turn determines response latency and threshold sensitivity of the ipRGCs. The poorly conserved region distal to the phosphorylation cluster inhibits phosphorylation's functional role, thereby constituting a unique delayed deactivation mechanism. Concerted action of both regions sustains responses to dim light, allows for the integration of light over time, and results in precise signal duration.
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Affiliation(s)
- Ludovic S Mure
- Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Megumi Hatori
- Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Quansheng Zhu
- Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - James Demas
- St. Olaf College, 1520 St. Olaf Avenue, Northfield, MN 55057, USA
| | - Irene M Kim
- Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Surendra K Nayak
- Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Satchidananda Panda
- Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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16
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Shirzad-Wasei N, DeGrip WJ. Heterologous expression of melanopsin: Present, problems and prospects. Prog Retin Eye Res 2016; 52:1-21. [DOI: 10.1016/j.preteyeres.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/25/2016] [Accepted: 02/01/2016] [Indexed: 12/12/2022]
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17
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Spoida K, Eickelbeck D, Karapinar R, Eckhardt T, Mark MD, Jancke D, Ehinger BV, König P, Dalkara D, Herlitze S, Masseck OA. Melanopsin Variants as Intrinsic Optogenetic On and Off Switches for Transient versus Sustained Activation of G Protein Pathways. Curr Biol 2016; 26:1206-12. [PMID: 27068418 DOI: 10.1016/j.cub.2016.03.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/09/2016] [Accepted: 03/01/2016] [Indexed: 10/22/2022]
Abstract
G-protein-coupled receptors (GPCRs) represent the major protein family for cellular modulation in mammals. Therefore, various strategies have been developed to analyze the function of GPCRs involving pharmaco- and optogenetic approaches [1, 2]. However, a tool that combines precise control of the activation and deactivation of GPCR pathways and/or neuronal firing with limited phototoxicity is still missing. We compared the biophysical properties and optogenetic application of a human and a mouse melanopsin variant (hOpn4L and mOpn4L) on the control of Gi/o and Gq pathways in heterologous expression systems and mouse brain. We found that GPCR pathways can be switched on/off by blue/yellow light. The proteins differ in their kinetics and wavelength dependence to activate and deactivate G protein pathways. Whereas mOpn4L is maximally activated by very short light pulses, leading to sustained G protein activation, G protein responses of hOpn4L need longer light pulses to be activated and decline in amplitude. Based on the different biophysical properties, brief light activation of mOpn4L is sufficient to induce sustained neuronal firing in cerebellar Purkinje cells (PC), whereas brief light activation of hOpn4L induces AP firing, which declines in frequency over time. Most importantly, mOpn4L-induced sustained firing can be switched off by yellow light. Based on the biophysical properties, hOpn4L and mOpn4L represent the first GPCR optogenetic tools, which can be used to switch GPCR pathways/neuronal firing on an off with temporal precision and limited phototoxicity. We suggest to name these tools moMo and huMo for future optogenetic applications.
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Affiliation(s)
- Katharina Spoida
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Dennis Eickelbeck
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Raziye Karapinar
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Tobias Eckhardt
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Melanie D Mark
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Dirk Jancke
- Optical Imaging Group, Institut für Neuroinformatik, NB 2/27, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Benedikt Valerian Ehinger
- Institute of Cognitive Science, University of Osnabrück, Albrechtstrasse 28, 49076 Osnabrück, Germany
| | - Peter König
- Institute of Cognitive Science, University of Osnabrück, Albrechtstrasse 28, 49076 Osnabrück, Germany; Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg Eppendorf, 20246 Hamburg, Germany
| | - Deniz Dalkara
- Sorbonne Universités, UPMC University Paris 06, INSERM, CNRS, Institut de la Vision, 17 Rue Moreau, 75012 Paris, France
| | - Stefan Herlitze
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany.
| | - Olivia A Masseck
- Department of General Zoology and Neurobiology, ND 7/31, Ruhr University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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18
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Pack W, Hill DD, Wong KY. Melatonin modulates M4-type ganglion-cell photoreceptors. Neuroscience 2015; 303:178-88. [PMID: 26141846 PMCID: PMC4532552 DOI: 10.1016/j.neuroscience.2015.06.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/30/2015] [Accepted: 06/23/2015] [Indexed: 11/21/2022]
Abstract
In the retina, melatonin is secreted at night by rod/cone photoreceptors and serves as a dark-adaptive signal. Melatonin receptors have been found in many retinal neurons including melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), suggesting it could modulate the physiology of these inner retinal photoreceptors. Here, we investigated whether melatonin modulates the alpha-like M4-type ipRGCs, which are believed to mediate image-forming vision as well as non-image-forming photoresponses. Applying melatonin during daytime (when endogenous melatonin secretion is low) caused whole-cell-recorded M4 cells' rod/cone-driven depolarizing photoresponses to become broader and larger, whereas the associated elevation in spike rate was reduced. Melanopsin-based light responses were not affected significantly. Nighttime application of the melatonin receptor antagonist luzindole also altered M4 cells' rod/cone-driven light responses but in the opposite ways: the duration and amplitude of the graded depolarization were reduced, whereas the accompanying spiking increase was enhanced. These luzindole-induced changes confirmed that M4 cells are modulated by endogenous melatonin. Melatonin could induce the above effects by acting directly on M4 cells because immunohistochemistry detected MT1 receptors in these cells, although it could also act presynaptically. Interestingly, the daytime and nighttime recordings showed significant differences in resting membrane potential, spontaneous spike rate and rod/cone-driven light responses, suggesting that M4 cells are under circadian control. This is the first report of a circadian variation in ipRGCs' resting properties and synaptic input, and of melatoninergic modulation of ipRGCs.
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Affiliation(s)
- W Pack
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States
| | - D D Hill
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States
| | - K Y Wong
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI 48105, United States; Department of Molecular, Cellular & Developmental Biology, University of Michigan, Ann Arbor, MI 48105, United States.
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19
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G-Protein Coupled Receptor Kinase 2 Minimally Regulates Melanopsin Activity in Intrinsically Photosensitive Retinal Ganglion Cells. PLoS One 2015; 10:e0128690. [PMID: 26069965 PMCID: PMC4467020 DOI: 10.1371/journal.pone.0128690] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/29/2015] [Indexed: 12/20/2022] Open
Abstract
Phosphorylation is a primary modulator of mammalian G-protein coupled receptor (GPCR) activity. The GPCR melanopsin is the photopigment of intrinsically photosensitive retinal ganglion cells (ipRGCs) in the mammalian retina. Recent evidence from in vitro experiments suggests that the G-protein coupled receptor kinase 2 (GRK2) phosphorylates melanopsin and reduces its activity following light exposure. Using an ipRGC-specific GRK2 loss-of-function mouse, we show that GRK2 loss alters melanopsin response dynamics and termination time in postnatal day 8 (P8) ipRGCs but not in older animals. However, the alterations are small in comparison to the changes reported for other opsins with loss of their cognate GRK. These results suggest GRK2 contributes to melanopsin deactivation, but that other mechanisms account for most of modulation of melanopsin activity in ipRGCs.
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20
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Co-expression of two subtypes of melatonin receptor on rat M1-type intrinsically photosensitive retinal ganglion cells. PLoS One 2015; 10:e0117967. [PMID: 25714375 PMCID: PMC4340921 DOI: 10.1371/journal.pone.0117967] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 12/15/2014] [Indexed: 12/15/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian and other non-image forming visual responses. An open question is whether the activity of these neurons may also be under the regulation mediated by the neurohormone melatonin. In the present work, by double-staining immunohistochemical technique, we studied the expression of MT1 and MT2, two known subtypes of mammalian melatonin receptors, in rat ipRGCs. A single subset of retinal ganglion cells labeled by the specific antibody against melanopsin exhibited the morphology typical of M1-type ipRGCs. Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons. Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth. It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.
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21
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Cameron EG, Robinson PR. β-Arrestin-dependent deactivation of mouse melanopsin. PLoS One 2014; 9:e113138. [PMID: 25401926 PMCID: PMC4234672 DOI: 10.1371/journal.pone.0113138] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/21/2014] [Indexed: 11/25/2022] Open
Abstract
In mammals, the expression of the unusual visual pigment, melanopsin, is restricted to a small subset of intrinsically photosensitive retinal ganglion cells (ipRGCs), whose signaling regulate numerous non-visual functions including sleep, circadian photoentrainment and pupillary constriction. IpRGCs exhibit attenuated electrical responses following sequential and prolonged light exposures indicative of an adaptational response. The molecular mechanisms underlying deactivation and adaptation in ipRGCs however, have yet to be fully elucidated. The role of melanopsin phosphorylation and β-arrestin binding in this adaptive process is suggested by the phosphorylation-dependent reduction of melanopsin signaling in vitro and the ubiquitous expression of β-arrestin in the retina. These observations, along with the conspicuous absence of visual arrestin in ipRGCs, suggest that a β-arrestin terminates melanopsin signaling. Here, we describe a light- and phosphorylation- dependent reduction in melanopsin signaling mediated by both β-arrestin 1 and β-arrestin 2. Using an in vitro calcium imaging assay, we demonstrate that increasing the cellular concentration of β-arrestin 1 and β-arrestin 2 significantly increases the rate of deactivation of light-activated melanopsin in HEK293 cells. Furthermore, we show that this response is dependent on melanopsin carboxyl-tail phosphorylation. Crosslinking and co-immunoprecipitation experiments confirm β-arrestin 1 and β-arrestin 2 bind to melanopsin in a light- and phosphorylation- dependent manner. These data are further supported by proximity ligation assays (PLA), which demonstrate a melanopsin/β-arrestin interaction in HEK293 cells and ipRGCs. Together, these results suggest that melanopsin signaling is terminated in a light- and phosphorylation-dependent manner through the binding of a β-arrestin within the retina.
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Affiliation(s)
- Evan G. Cameron
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland, United States of America
| | - Phyllis R. Robinson
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland, United States of America
- * E-mail:
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22
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Sodhi P, Hartwick ATE. Adenosine modulates light responses of rat retinal ganglion cell photoreceptors througha cAMP-mediated pathway. J Physiol 2014; 592:4201-20. [PMID: 25038240 DOI: 10.1113/jphysiol.2014.276220] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Adenosine is an established neuromodulator in the mammalian retina, with A1 adenosine receptors being especially prevalent in the innermost ganglion cell layer. Activation of A1 receptors causes inhibition of adenylate cyclase, decreases in intracellular cyclic AMP (cAMP) levels and inhibition of protein kinase A (PKA). In this work, our aim was to characterize the effects of adenosine on the light responses of intrinsically photosensitive retinal ganglion cells (ipRGCs) and to determine whether these photoreceptors are subject to neuromodulation through intracellular cAMP-related signalling pathways. Using multielectrode array recordings from postnatal and adult rat retinas, we demonstrated that adenosine significantly shortened the duration of ipRGC photoresponses and reduced the number of light-evoked spikes fired by these neurons. The effects were A1 adenosine receptor-mediated, and the expression of this receptor on melanopsin-containing ipRGCs was confirmed by calcium imaging experiments on isolated cells in purified cultures. While inhibition of the cAMP/PKA pathway by adenosine shortened ipRGC light responses, stimulation of this pathway with compounds such as forskolin had the opposite effect and lengthened the duration of ipRGC spiking. Our findings reveal that the modification of ipRGC photoresponses through a cAMP/PKA pathway is a general feature of rat ganglion cell photoreceptors, and this pathway can be inhibited through activation of A1 receptors by adenosine. As adenosine levels in the retina rise at night, adenosinergic modulation of ipRGCs may serve as an internal regulatory mechanism to limit transmission of nocturnal photic signals by ipRGCs to the brain. Targeting retinal A1 adenosine receptors for ipRGC inhibition represents a potential therapeutic target for sleep disorders and migraine-associated photophobia.
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Affiliation(s)
- Puneet Sodhi
- Department of Neuroscience, Ohio State University, Columbus, OH, 43210, USA
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23
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Blanco-Sánchez B, Clément A, Fierro J, Washbourne P, Westerfield M. Complexes of Usher proteins preassemble at the endoplasmic reticulum and are required for trafficking and ER homeostasis. Dis Model Mech 2014; 7:547-59. [PMID: 24626987 PMCID: PMC4007406 DOI: 10.1242/dmm.014068] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Usher syndrome (USH), the leading cause of hereditary combined hearing and vision loss, is characterized by sensorineural deafness and progressive retinal degeneration. Mutations in several different genes produce USH, but the proximal cause of sensory cell death remains mysterious. We adapted a proximity ligation assay to analyze associations among three of the USH proteins, Cdh23, Harmonin and Myo7aa, and the microtubule-based transporter Ift88 in zebrafish inner ear mechanosensory hair cells. We found that the proteins are in close enough proximity to form complexes and that these complexes preassemble at the endoplasmic reticulum (ER). Defects in any one of the three USH proteins disrupt formation and trafficking of the complex and result in diminished levels of the other proteins, generalized trafficking defects and ER stress that triggers apoptosis. ER stress, thus, contributes to sensory hair cell loss and provides a new target to explore for protective therapies for USH.
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Large scale expression and purification of mouse melanopsin-L in the baculovirus expression system. Protein Expr Purif 2013; 91:134-46. [PMID: 23921072 DOI: 10.1016/j.pep.2013.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 07/14/2013] [Accepted: 07/17/2013] [Indexed: 11/22/2022]
Abstract
Melanopsin is the mammalian photopigment that primarily mediates non-visual photoregulated physiology. So far, this photopigment is poorly characterized with respect to structure and function. Here, we report large-scale production and purification of the intact long isoform of mouse melanopsin (melanopsin-L) using the baculovirus/insect cell expression system. Exploiting the baculoviral GP67 signal peptide, we obtained expression levels that varied between 10-30pmol/10(6)cells, equivalent to 2-5mg/L. This could be further enhanced using DMSO as a chemical chaperone. LC-MS analysis confirmed that full-length melanopsin-L was expressed and demonstrated that the majority of the expressed protein was N-glycosylated at Asn(30) and Asn(34). Other posttranslational modifications were not yet detected. Purification was achieved exploiting a C-terminal deca-histag, realizing a purification factor of several hundred-fold. The final recovery of purified melanopsin-L averaged 2.5% of the starting material. This was mainly due to low extraction yields, probably since most of the protein was present as the apoprotein. The spectral data we obtained agree with an absorbance maximum in the 460-500nm wavelength region and a significant red-shift upon illumination. This is the first report on expression and purification of full length melanopsin-L at a scale that can easily be further amplified.
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25
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Adaptation to steady light by intrinsically photosensitive retinal ganglion cells. Proc Natl Acad Sci U S A 2013; 110:7470-5. [PMID: 23589882 DOI: 10.1073/pnas.1304039110] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are recently discovered photoreceptors in the mammalian eye. These photoreceptors mediate primarily nonimage visual functions, such as pupillary light reflex and circadian photoentrainment, which are generally expected to respond to the absolute light intensity. The classical rod and cone photoreceptors, on the other hand, mediate image vision by signaling contrast, accomplished by adaptation to light. Experiments by others have indicated that the ipRGCs do, in fact, light-adapt. We found the same but, in addition, have now quantified this light adaptation for the M1 ipRGC subtype. Interestingly, in incremental-flash-on-background experiments, the ipRGC's receptor current showed a flash sensitivity that adapted in background light according to the Weber-Fechner relation, well known to describe the adaptation behavior of rods and cones. Part of this light adaptation by ipRGCs appeared to be triggered by a Ca(2+) influx, in that the flash response elicited in the absence of extracellular Ca(2+) showed a normal rising phase but a slower decay phase, resulting in longer time to peak and higher sensitivity. There is, additionally, a prominent Ca(2+)-independent component of light adaptation not typically seen in rods and cones or in invertebrate rhabdomeric photoreceptors.
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