1
|
Chai Z, Ye Y, Silverman D, Rose K, Madura A, Reed RR, Chen J, Yau KW. Dark continuous noise from mutant G90D-rhodopsin predominantly underlies congenital stationary night blindness. Proc Natl Acad Sci U S A 2024; 121:e2404763121. [PMID: 38743626 PMCID: PMC11127052 DOI: 10.1073/pnas.2404763121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 04/17/2024] [Indexed: 05/16/2024] Open
Abstract
Congenital stationary night blindness (CSNB) is an inherited retinal disease that causes a profound loss of rod sensitivity without severe retinal degeneration. One well-studied rhodopsin point mutant, G90D-Rho, is thought to cause CSNB because of its constitutive activity in darkness causing rod desensitization. However, the nature of this constitutive activity and its precise molecular source have not been resolved for almost 30 y. In this study, we made a knock-in (KI) mouse line with a very low expression of G90D-Rho (equal in amount to ~0.1% of normal rhodopsin, WT-Rho, in WT rods), with the remaining WT-Rho replaced by REY-Rho, a mutant with a very low efficiency of activating transducin due to a charge reversal of the highly conserved ERY motif to REY. We observed two kinds of constitutive noise: one being spontaneous isomerization (R*) of G90D-Rho at a molecular rate (R* s-1) 175-fold higher than WT-Rho and the other being G90D-Rho-generated dark continuous noise comprising low-amplitude unitary events occurring at a very high molecular rate equivalent in effect to ~40,000-fold of R* s-1 from WT-Rho. Neither noise type originated from G90D-Opsin because exogenous 11-cis-retinal had no effect. Extrapolating the above observations at low (0.1%) expression of G90D-Rho to normal disease exhibited by a KI mouse model with RhoG90D/WTand RhoG90D/G90D genotypes predicts the disease condition very well quantitatively. Overall, the continuous noise from G90D-Rho therefore predominates, constituting the major equivalent background light causing rod desensitization in CSNB.
Collapse
Affiliation(s)
- Zuying Chai
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Yaqing Ye
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Daniel Silverman
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
- Biochemistry, Cellular and Molecular Biology Graduate Program, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Kasey Rose
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Alana Madura
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - Randall R. Reed
- Department of Molecular Biology and Genetics (Emeritus), Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Jeannie Chen
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA90033
| | - King-Wai Yau
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
| |
Collapse
|
2
|
Correlation between the Serum Concentration of Vitamin A and Disease Severity in Patients Carrying p.G90D in RHO, the Most Frequent Gene Associated with Dominant Retinitis Pigmentosa: Implications for Therapy with Vitamin A. Int J Mol Sci 2023; 24:ijms24010780. [PMID: 36614223 PMCID: PMC9821079 DOI: 10.3390/ijms24010780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/19/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023] Open
Abstract
The pathogenic variant p.G90D in RHO is believed to be responsible for a spectrum of phenotypes, including congenital stationary blindness (for the purpose of this study termed night blindness without degeneration; NBWD), Sector RP, Pericentral RP, and Classic RP. We present a correlation between the serum concentration of vitamin A and disease severity in patients with this variant. This prospective study involved 30 patients from 7 families (17 male; median age 46 years, range 8−73). Full ophthalmological examination including visual acuity, Goldmann perimetry, slit-lamp exam, optical coherence tomography, fundus autofluorescence, and electrophysiology was performed to determine the presenting phenotype. The serum concentration of vitamin A was determined from a fasting blood sample taken on the day of the exam, where it was found that 23.3% (7/30) of patients had NBWD, 13.3% (4/30) had Sector RP, 3.3% (1/30) had Pericentral RP, and 60% (18/30) had Classic RP. Multiple logistic regression revealed a significantly higher probability of having a milder phenotype (NBWD or Sector RP) in association with younger age (p < 0.05) and a higher concentration of vitamin A (p < 0.05). We hypothesize that vitamin A in its 11-cis-retinal form plays a role in stabilizing the constitutively active p.G90D rhodopsin and its supplementation could be a potential treatment strategy for p.G90D RHO patients.
Collapse
|
3
|
Fanelli F, Felline A, Marigo V. Structural aspects of rod opsin and their implication in genetic diseases. Pflugers Arch 2021; 473:1339-1359. [PMID: 33728518 DOI: 10.1007/s00424-021-02546-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 01/04/2023]
Abstract
Vision in dim-light conditions is triggered by photoactivation of rhodopsin, the visual pigment of rod photoreceptor cells. Rhodopsin is made of a protein, the G protein coupled receptor (GPCR) opsin, and the chromophore 11-cis-retinal. Vertebrate rod opsin is the GPCR best characterized at the atomic level of detail. Since the release of the first crystal structure 20 years ago, a huge number of structures have been released that, in combination with valuable spectroscopic determinations, unveiled most aspects of the photobleaching process. A number of spontaneous mutations of rod opsin have been found linked to vision-impairing diseases like autosomal dominant or autosomal recessive retinitis pigmentosa (adRP or arRP, respectively) and autosomal congenital stationary night blindness (adCSNB). While adCSNB is mainly caused by constitutive activation of rod opsin, RP shows more variegate determinants affecting different aspects of rod opsin function. The vast majority of missense rod opsin mutations affects folding and trafficking and is linked to adRP, an incurable disease that awaits light on its molecular structure determinants. This review article summarizes all major structural information available on vertebrate rod opsin conformational states and the insights gained so far into the structural determinants of adCSNB and adRP linked to rod opsin mutations. Strategies to design small chaperones with therapeutic potential for selected adRP rod opsin mutants will be discussed as well.
Collapse
Affiliation(s)
- Francesca Fanelli
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, 41125, Modena, Italy. .,Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, via Campi 287, Modena, 41125, Italy.
| | - Angelo Felline
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, 41125, Modena, Italy
| | - Valeria Marigo
- Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, via Campi 287, Modena, 41125, Italy.,Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 287, 41125, Modena, Italy
| |
Collapse
|
4
|
Kobal N, Krašovec T, Šuštar M, Volk M, Peterlin B, Hawlina M, Fakin A. Stationary and Progressive Phenotypes Caused by the p.G90D Mutation in Rhodopsin Gene. Int J Mol Sci 2021; 22:ijms22042133. [PMID: 33669941 PMCID: PMC7924842 DOI: 10.3390/ijms22042133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 12/30/2022] Open
Abstract
Mutations in rhodopsin gene (RHO) are a frequent cause of retinitis pigmentosa (RP) and less often, congenital stationary night blindness (CSNB). Mutation p.G90D has previously been associated with CSNB based on the examination of one family. This study screened 60 patients. Out of these 60 patients, 32 were affected and a full characterization was conducted in 15 patients. We described the clinical characteristics of these 15 patients (12 male, median age 42 years, range 8-71) from three families including visual field (Campus Goldmann), fundus autofluorescence (FAF), optical coherence tomography (OCT) and electrophysiology. Phenotypes were classified into four categories: CSNB (N = 3, 20%) sector RP (N = 3, 20%), pericentral RP (N = 1, 6.7%) and classic RP (N = 8, 53.3% (8/15)). The phenotypes were not associated with family, sex or age (Kruskal-Wallis, p > 0.05), however, cystoid macular edema (CME) was observed only in one family. Among the subjects reporting nyctalopia, 69% (22/32) were male. The clinical characteristics of the largest p.G90D cohort so far showed a large frequency of progressive retinal degeneration with 53.3% developing RP, contrary to the previous report.
Collapse
Affiliation(s)
- Nina Kobal
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Tjaša Krašovec
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Maja Šuštar
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Marija Volk
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (B.P.)
| | - Borut Peterlin
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (B.P.)
| | - Marko Hawlina
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
| | - Ana Fakin
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva ulica 46, 1000 Ljubljana, Slovenia; (N.K.); (T.K.); (M.Š.); (M.H.)
- Correspondence:
| |
Collapse
|
5
|
Pope AL, Sanchez-Reyes OB, South K, Zaitseva E, Ziliox M, Vogel R, Reeves PJ, Smith SO. A Conserved Proline Hinge Mediates Helix Dynamics and Activation of Rhodopsin. Structure 2020; 28:1004-1013.e4. [PMID: 32470317 DOI: 10.1016/j.str.2020.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/24/2020] [Accepted: 05/11/2020] [Indexed: 01/05/2023]
Abstract
Despite high-resolution crystal structures of both inactive and active G protein-coupled receptors (GPCRs), it is still not known how ligands trigger the large structural change on the intracellular side of the receptor since the conformational changes that occur within the extracellular ligand-binding region upon activation are subtle. Here, we use solid-state NMR and Fourier transform infrared spectroscopy on rhodopsin to show that Trp2656.48 within the CWxP motif on transmembrane helix H6 constrains a proline hinge in the inactive state, suggesting that activation results in unraveling of the H6 backbone within this motif, a local change in dynamics that allows helix H6 to swing outward. Notably, Tyr3017.48 within activation switch 2 appears to mimic the negative allosteric sodium ion found in other family A GPCRs, a finding that is broadly relevant to the mechanism of receptor activation.
Collapse
Affiliation(s)
- Andreyah L Pope
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Omar B Sanchez-Reyes
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Kieron South
- School of Life Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK
| | - Ekaterina Zaitseva
- Biophysics Section, Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University, Freiburg, Hermann Herder Strasse, 79104 Freiburg, Germany
| | - Martine Ziliox
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Reiner Vogel
- Biophysics Section, Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University, Freiburg, Hermann Herder Strasse, 79104 Freiburg, Germany
| | - Philip J Reeves
- School of Life Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
| |
Collapse
|
6
|
Heterozygous RHO p.R135W missense mutation in a large Han-Chinese family with retinitis pigmentosa and different refractive errors. Biosci Rep 2019; 39:BSR20182198. [PMID: 31239368 PMCID: PMC6629948 DOI: 10.1042/bsr20182198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 05/28/2019] [Accepted: 06/24/2019] [Indexed: 12/14/2022] Open
Abstract
Retinitis pigmentosa (RP), the most common type of inherited retinal degeneration causing blindness, initially manifests as severely impaired rod function followed by deteriorating cone function. Mutations in the rhodopsin gene (RHO) are the most common cause of autosomal dominant RP (adRP). The present study aims to identify the disease-causing mutation in a numerous, four-generation Han-Chinese family with adRP detected by whole exome sequencing and Sanger sequencing. Afflicted family members present classic adRP along with heterogeneous clinical phenotypes including differing refractive errors, cataracts, astigmatism and epiretinal membranes. A missense mutation, c.403C>T (p.R135W), in the RHO gene was identified in nine subjects and it co-segregated with family members. The mutation is predicted to be disease-causing and results in rhodopsin protein abnormalities. The present study extends the genotype-phenotype relationship between RHO gene mutations and adRP clinical findings. The results have implications for familial genetic counseling, clinical management and developing RP target gene therapy strategies.
Collapse
|
7
|
Abstract
Serotonin (5-hydroxytryptamine, 5-HT)2A receptor agonists have recently emerged as promising new treatment options for a variety of disorders. The recent success of these agonists, also known as psychedelics, like psilocybin for the treatment of anxiety, depression, obsessive-compulsive disorder (OCD), and addiction, has ushered in a renaissance in the way these compounds are perceived in the medical community and populace at large. One emerging therapeutic area that holds significant promise is their use as anti-inflammatory agents. Activation of 5-HT2A receptors produces potent anti-inflammatory effects in animal models of human inflammatory disorders at sub-behavioural levels. This review discusses the role of the 5-HT2A receptor in the inflammatory response, as well as highlight studies using the 5-HT2A agonist (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] to treat inflammation in cellular and animal models. It also examines potential mechanisms by which 5-HT2A agonists produce their therapeutic effects. Overall, psychedelics regulate inflammatory pathways via novel mechanisms, and may represent a new and exciting treatment strategy for several inflammatory disorders.
Collapse
Affiliation(s)
- Thomas W Flanagan
- a Department of Pharmacology and Experimental Therapeutics , Louisiana State University Health Sciences Center , New Orleans , LA , USA
| | - Charles D Nichols
- a Department of Pharmacology and Experimental Therapeutics , Louisiana State University Health Sciences Center , New Orleans , LA , USA
| |
Collapse
|
8
|
de Assis LVM, Moraes MN, Castrucci AMDL. Heat shock antagonizes UVA-induced responses in murine melanocytes and melanoma cells: an unexpected interaction. Photochem Photobiol Sci 2018; 16:633-648. [PMID: 28203671 DOI: 10.1039/c6pp00330c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The skin is under the influence of oscillatory factors such as light and temperature. This organ possesses a local system that controls several aspects in a time-dependent manner; moreover, the skin has a well-known set of opsins whose function is still unknown. We demonstrate that heat shock reduces Opn2 expression in normal Melan-a melanocytes, while the opposite effect is found in malignant B16-F10 cells. In both cell lines, UVA radiation increases the expression of Opn4 and melanin content. Clock genes and Xpa, a DNA repair gene, of malignant melanocytes are more responsive to UVA radiation when compared to normal cells. Most UVA-induced effects are antagonized by heat shock, a phenomenon shown for the first time. Based on our data, the heat produced during UV experiments should be carefully monitored since temperature represents, according to our results, an important confounding factor, and therefore it should, when possible, be dissociated from UV radiation. The responses displayed by murine melanoma cells, if proven to also take place in human melanoma, may represent an important step in cancer development and progression.
Collapse
Affiliation(s)
- Leonardo Vinícius Monteiro de Assis
- Laboratory of Comparative Physiology of Pigmentation, Department of Physiology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil.
| | | | | |
Collapse
|
9
|
Krebs MP, Collin GB, Hicks WL, Yu M, Charette JR, Shi LY, Wang J, Naggert JK, Peachey NS, Nishina PM. Mouse models of human ocular disease for translational research. PLoS One 2017; 12:e0183837. [PMID: 28859131 PMCID: PMC5578669 DOI: 10.1371/journal.pone.0183837] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/12/2017] [Indexed: 01/24/2023] Open
Abstract
Mouse models provide a valuable tool for exploring pathogenic mechanisms underlying inherited human disease. Here, we describe seven mouse models identified through the Translational Vision Research Models (TVRM) program, each carrying a new allele of a gene previously linked to retinal developmental and/or degenerative disease. The mutations include four alleles of three genes linked to human nonsyndromic ocular diseases (Aipl1tvrm119, Aipl1tvrm127, Rpgrip1tvrm111, RhoTvrm334) and three alleles of genes associated with human syndromic diseases that exhibit ocular phentoypes (Alms1tvrm102, Clcn2nmf289, Fkrptvrm53). Phenotypic characterization of each model is provided in the context of existing literature, in some cases refining our current understanding of specific disease attributes. These murine models, on fixed genetic backgrounds, are available for distribution upon request and may be useful for understanding the function of the gene in the retina, the pathological mechanisms induced by its disruption, and for testing experimental approaches to treat the corresponding human ocular diseases.
Collapse
Affiliation(s)
- Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wanda L. Hicks
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | | | - Lan Ying Shi
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| |
Collapse
|
10
|
Wacker D, Stevens RC, Roth BL. How Ligands Illuminate GPCR Molecular Pharmacology. Cell 2017; 170:414-427. [PMID: 28753422 DOI: 10.1016/j.cell.2017.07.009] [Citation(s) in RCA: 366] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/13/2017] [Accepted: 07/11/2017] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs), which are modulated by a variety of endogenous and synthetic ligands, represent the largest family of druggable targets in the human genome. Recent structural and molecular studies have both transformed and expanded classical concepts of receptor pharmacology and have begun to illuminate the distinct mechanisms by which structurally, chemically, and functionally diverse ligands modulate GPCR function. These molecular insights into ligand engagement and action have enabled new computational methods and accelerated the discovery of novel ligands and tool compounds, especially for understudied and orphan GPCRs. These advances promise to streamline the development of GPCR-targeted medications.
Collapse
Affiliation(s)
- Daniel Wacker
- Department of Pharmacology and Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27514, USA
| | - Raymond C Stevens
- Departments of Biological Sciences and Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA 90089, USA
| | - Bryan L Roth
- Department of Pharmacology and Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27514, USA.
| |
Collapse
|
11
|
Singhal A, Guo Y, Matkovic M, Schertler G, Deupi X, Yan EC, Standfuss J. Structural role of the T94I rhodopsin mutation in congenital stationary night blindness. EMBO Rep 2016; 17:1431-1440. [PMID: 27458239 DOI: 10.15252/embr.201642671] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/07/2016] [Indexed: 11/09/2022] Open
Abstract
Congenital stationary night blindness (CSNB) is an inherited and non-progressive retinal dysfunction. Here, we present the crystal structure of CSNB-causing T94I2.61 rhodopsin in the active conformation at 2.3 Å resolution. The introduced hydrophobic side chain prolongs the lifetime of the G protein activating metarhodopsin-II state by establishing a direct van der Waals contact with K2967.43, the site of retinal attachment. This is in stark contrast to the light-activated state of the CSNB-causing G90D2.57 mutation, where the charged mutation forms a salt bridge with K2967.43 To find the common denominator between these two functional modifications, we combined our structural data with a kinetic biochemical analysis and molecular dynamics simulations. Our results indicate that both the charged G90D2.57 and the hydrophobic T94I2.61 mutation alter the dark state by weakening the interaction between the Schiff base (SB) and its counterion E1133.28 We propose that this interference with the tight regulation of the dim light photoreceptor rhodopsin increases background noise in the visual system and causes the loss of night vision characteristic for CSNB patients.
Collapse
Affiliation(s)
- Ankita Singhal
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Ying Guo
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Milos Matkovic
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| | - Gebhard Schertler
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland Deparment of Biology, ETH Zurich, Zürich, Switzerland
| | - Xavier Deupi
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland Condensed Matter Theory Group, Paul Scherrer Institute, Villigen, Switzerland
| | - Elsa Cy Yan
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Joerg Standfuss
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
| |
Collapse
|
12
|
Jastrzebska B. GPCR: G protein complexes--the fundamental signaling assembly. Amino Acids 2013; 45:1303-14. [PMID: 24052187 DOI: 10.1007/s00726-013-1593-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 09/10/2013] [Indexed: 12/15/2022]
Abstract
G protein coupled receptors (GPCR) constitute the largest group of cell surface receptors that transmit various signals across biological membranes through the binding and activation of heterotrimeric G proteins, which amplify the signal and activate downstream effectors leading to the biological responses. Thus, the first critical step in this signaling cascade is the interaction between receptor and its cognate G protein. Understanding this critical event at the molecular level is of high importance because abnormal function of GPCRs is associated with many diseases. Thus, these receptors are targets for drug development.
Collapse
Affiliation(s)
- Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106-4965, USA,
| |
Collapse
|
13
|
Insights into congenital stationary night blindness based on the structure of G90D rhodopsin. EMBO Rep 2013; 14:520-6. [PMID: 23579341 DOI: 10.1038/embor.2013.44] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/12/2013] [Accepted: 03/17/2013] [Indexed: 01/05/2023] Open
Abstract
We present active-state structures of the G protein-coupled receptor (GPCRs) rhodopsin carrying the disease-causing mutation G90D. Mutations of G90 cause either retinitis pigmentosa (RP) or congenital stationary night blindness (CSNB), a milder, non-progressive form of RP. Our analysis shows that the CSNB-causing G90D mutation introduces a salt bridge with K296. The mutant thus interferes with the E113Q-K296 activation switch and the covalent binding of the inverse agonist 11-cis-retinal, two interactions that are crucial for the deactivation of rhodopsin. Other mutations, including G90V causing RP, cannot promote similar interactions. We discuss our findings in context of a model in which CSNB is caused by constitutive activation of the visual signalling cascade.
Collapse
|
14
|
Reprogramming of adult rod photoreceptors prevents retinal degeneration. Proc Natl Acad Sci U S A 2013; 110:1732-7. [PMID: 23319618 DOI: 10.1073/pnas.1214387110] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A prime goal of regenerative medicine is to direct cell fates in a therapeutically useful manner. Retinitis pigmentosa is one of the most common degenerative diseases of the eye and is associated with early rod photoreceptor death followed by secondary cone degeneration. We hypothesized that converting adult rods into cones, via knockdown of the rod photoreceptor determinant Nrl, could make the cells resistant to the effects of mutations in rod-specific genes, thereby preventing secondary cone loss. To test this idea, we engineered a tamoxifen-inducible allele of Nrl to acutely inactivate the gene in adult rods. This manipulation resulted in reprogramming of rods into cells with a variety of cone-like molecular, histologic, and functional properties. Moreover, reprogramming of adult rods achieved cellular and functional rescue of retinal degeneration in a mouse model of retinitis pigmentosa. These findings suggest that elimination of Nrl in adult rods may represent a unique therapy for retinal degeneration.
Collapse
|
15
|
Abstract
GPCRs (G-protein-coupled receptors) are seven-transmembrane helix proteins that transduce exogenous and endogenous signals to modulate the activity of downstream effectors inside the cell. Despite the relevance of these proteins in human physiology and pharmaceutical research, we only recently started to understand the structural basis of their activation mechanism. In the period 2008-2011, nine active-like structures of GPCRs were solved. Among them, we have determined the structure of light-activated rhodopsin with all the features of the active metarhodopsin-II, which represents so far the most native-like model of an active GPCR. This structure, together with the structures of other inactive, intermediate and active states of rhodopsin constitutes a unique structural framework on which to understand the conserved aspects of the activation mechanism of GPCRs. This mechanism can be summarized as follows: retinal isomerization triggers a series of local structural changes in the binding site that are amplified into three intramolecular activation pathways through TM (transmembrane helix) 5/TM3, TM6 and TM7/TM2. Sequence analysis strongly suggests that these pathways are conserved in other GPCRs. Differential activation of these pathways by ligands could be translated into the stabilization of different active states of the receptor with specific signalling properties.
Collapse
|
16
|
Toledo D, Ramon E, Aguilà M, Cordomí A, Pérez JJ, Mendes HF, Cheetham ME, Garriga P. Molecular mechanisms of disease for mutations at Gly-90 in rhodopsin. J Biol Chem 2011; 286:39993-40001. [PMID: 21940625 DOI: 10.1074/jbc.m110.201517] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two different mutations at Gly-90 in the second transmembrane helix of the photoreceptor protein rhodopsin have been proposed to lead to different phenotypes. G90D has been classically associated with congenital night blindness, whereas the newly reported G90V substitution was linked to a retinitis pigmentosa phenotype. Here, we used Val/Asp replacements of the native Gly at position 90 to unravel the structure/function divergences caused by these mutations and the potential molecular mechanisms of inherited retinal disease. The G90V and G90D mutants have a similar conformation around the Schiff base linkage region in the dark state and same regeneration kinetics with 11-cis-retinal, but G90V has dramatically reduced thermal stability when compared with the G90D mutant rhodopsin. The G90V mutant also shows, like G90D, an altered photobleaching pattern and capacity to activate Gt in the opsin state. Furthermore, the regeneration of the G90V mutant with 9-cis-retinal was improved, achieving the same A(280)/A(500) as wild type isorhodopsin. Hydroxylamine resistance was also recovered, indicating a compact structure around the Schiff base linkage, and the thermal stability was substantially improved when compared with the 11-cis-regenerated mutant. These results support the role of thermal instability and/or abnormal photoproduct formation in eliciting a retinitis pigmentosa phenotype. The improved stability and more compact structure of the G90V mutant when it was regenerated with 9-cis-retinal brings about the possibility that this isomer or other modified retinoid analogues might be used in potential treatment strategies for mutants showing the same structural features.
Collapse
Affiliation(s)
- Darwin Toledo
- Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain
| | | | | | | | | | | | | | | |
Collapse
|