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rhodopsin

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https://www.readbyqxmd.com/read/28088625/absence-of-dj-1-causes-age-related-retinal-abnormalities-in-association-with-increased-oxidative-stress
#1
Vera L Bonilha, Brent A Bell, Mary E Rayborn, Ivy S Samuels, Anna King, Joe G Hollyfield, Chengsong Xie, Huaibin Cai
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed...
January 11, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28087932/the-complexity-of-fungal-vision
#2
Reinhard Fischer, Jesus Aguirre, Alfredo Herrera-Estrella, Luis M Corrochano
Life, as we know it, would not be possible without light. Light is not only a primary source of energy, but also an important source of information for many organisms. To sense light, only a few photoreceptor systems have developed during evolution. They are all based on an organic molecule with conjugated double bonds that allows energy transfer from visible (or UV) light to its cognate protein to translate the primary physical photoresponse to cell-biological actions. The three main classes of receptors are flavin-based blue-light, retinal-based green-light (such as rhodopsin), and linear tetrapyrrole-based red-light sensors...
December 2016: Microbiology Spectrum
https://www.readbyqxmd.com/read/28076806/measurement-of-slow-spontaneous-release-of%C3%A2-11-cis-retinal-from-rhodopsin
#3
He Tian, Thomas P Sakmar, Thomas Huber
The vertebrate visual photoreceptor rhodopsin (Rho) is a unique G protein-coupled receptor as it utilizes a covalently tethered inverse agonist (11-cis-retinal) as the native ligand. Previously, electrophysiological studies showed that ligand binding of 11-cis-retinal in dark-adapted Rho was essentially irreversible with a half-life estimated to be 420 years, until after thermal isomerization to all-trans-retinal, which then slowly dissociates. This long lifetime of 11-cis-retinal binding was considered to be physiologically important for minimizing background signal (dark noise) of the visual system...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28073248/interplay-of-g-protein-coupled-receptors-with-the-membrane-insights-from-supra-atomic-coarse-grain-molecular-dynamics-simulations
#4
Xavier Periole
G protein-coupled receptors (GPCRs) are central to many fundamental cellular signaling pathways. They transduce signals from the outside to the inside of cells in physiological processes ranging from vision to immune response. It is extremely challenging to look at them individually using conventional experimental techniques. Recently, a pseudo atomistic molecular model has emerged as a valuable tool to access information on GPCRs, more specifically on their interactions with their environment in their native cell membrane and the consequences on their supramolecular organization...
January 11, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28072545/ultrafast-photoinduced-deactivation-dynamics-of-proteorhodopsin
#5
C Elias Eckert, Jagdeep Kaur, Clemens Glaubitz, Josef Wachtveitl
We report femtosecond time-resolved absorption change measurements of the photoinduced deactivation dynamics of a microbial rhodopsin in the ultraviolet-visible and mid-infrared range. The blue light quenching process is recorded in green proteorhodopsin's (GPR) primary proton donor mutant E108Q from the deprotonated 13-cis photointermediate. The return of GPR to the dark state occurs in two steps, starting with the photoinduced 13-cis to all-trans reisomerization of the retinal. The subsequent Schiff base reprotonation via the primary proton acceptor (D97) occurs on a nanosecond time scale...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28065882/rescue-of-mutant-rhodopsin-traffic-by-metformin-induced-ampk-activation-accelerates-photoreceptor-degeneration
#6
Dimitra Athanasiou, Monica Aguila, Chikwado A Opefi, Kieron South, James Bellingham, Dalila Bevilacqua, Peter M Munro, Naheed Kanuga, Francesca E Mackenzie, Adam M Dubis, Anastasios Georgiadis, Anna B Graca, Rachael A Pearson, Robin R Ali, Sanae Sakami, Krzysztof Palczewski, Michael Y Sherman, Philip J Reeves, Michael E Cheetham
Protein misfolding caused by inherited mutations leads to loss of protein function and potentially toxic 'gain of function', such as the dominant P23H rhodopsin mutation that causes retinitis pigmentosa (RP). Here, we tested whether the AMPK activator metformin could affect the P23H rhodopsin synthesis and folding. In cell models, metformin treatment improved P23H rhodopsin folding and traffic. In animal models of P23H RP, metformin treatment successfully enhanced P23H traffic to the rod outer segment, but this led to reduced photoreceptor function and increased photoreceptor cell death...
January 7, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28062154/phototransduction-early-steps-model-based-on-beer-lambert-optical-law
#7
Ezequiel M Salido, Leonardo N Servalli, Juan Carlos Gomez, Claudio Verrastro
The amount of available rhodopsin on the photoreceptor outer segment and its change over time is not considered in classic models of phototransduction. Thus, those models do not take into account the absorptance variation of the outer segment under different brightness conditions. The relationship between the light absorbed by a medium and its absorptance is well described by the Beer-Lambert law. This newly proposed model implements the absorptance variation phenomenon in a set of equations that admit photons per second as input and results in active rhodopsins per second as output...
January 3, 2017: Vision Research
https://www.readbyqxmd.com/read/28058692/comparative-characteristics-of-two-anion-channel-rhodopsins-and-prospects-of-their-use-in-optogenetics
#8
D A Dolgikh, A Yu Malyshev, M V Roshchin, G R Smirnova, O V Nekrasova, L E Petrovskaya, T B Feldman, P M Balaban, M P Kirpichnikov, M A Ostrovsky
Anion-selective opsins slow ChloC and ACR2 were expressed in rat brain cortical neurons by electroporation in utero. It is shown that the light-activated channel ACR2 has pronounced advantages in terms of both the inactivation kinetics and the neuron inhibition intensity, which is associated with a more negative value of the light-activated current reversal potential compared to the slow ChloC channel. The identified properties of opsin ACR2 indicate that it can be used for strictly controlled suppression of neuronal activity in optogenetic experiments, including the expression in the retinal ganglionic cells for reconstituting the OFF-component of their receptive field, which is essential for optogenetic prosthetics of degenerative retina...
November 2016: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28058680/quantum-classical-model-of-retinal-photoisomerization-reaction-in-visual-pigment-rhodopsin
#9
V D Lakhno, A S Shigaev, T B Feldman, V A Nadtochenko, M A Ostrovsky
A quantum-classical model of photoisomerization of the visual pigment rhodopsin chromophore is proposed. At certain (and more realistic) parameter value combinations, the model is shown to accurately reproduce a number of independent experimental data on the photoreaction dynamics: the quantum yield, the time to reach the point of conical intersection of potential energy surfaces, the termination time of the evolution of quantum subsystem, as well as the characteristic low frequencies of retinal molecular lattice fluctuations during photoisomerization...
November 2016: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28040890/solid-state-nmr-structural-study-of-retinal-binding-pocket-in-sodium-ion-pump-rhodopsin
#10
Arisu Shigeta, Shota Ito, Keiichi Inoue, Takashi Okitsu, Akimori Wada, Hideki Kandori, Izuru Kawamura
The recently identified Krokinobacter rhodopsin 2 (KR2) functions as a light-driven sodium ion pump. The structure of the retinal-binding pocket of KR2 offers important in-sights into the mechanisms of KR2, which has an Asn112, Asp116, and Gln123 motif (NDQ) that is common among sodium ion pump rhodopsins, but is unique among other microbial rhodopsins. Here we present solid-state nuclear magnetic resonance (NMR) characterization of retinal and functionally important residues in the vicinity of retinal at ground state...
January 1, 2017: Biochemistry
https://www.readbyqxmd.com/read/28031289/attenuated-pupillary-light-responses-and-downregulation-of-opsin-expression-parallel-decline-in-circadian-disruption-in-two-different-mouse-models-of-huntington-s-disease
#11
Koliane Ouk, Steven Hughes, Carina A Pothecary, Stuart N Peirson, A Jennifer Morton
Circadian deficits in Huntington's disease (HD) are recapitulated in both fragment (R6/2) and full-length (Q175) mouse models of HD. Circadian rhythms are regulated by the suprachiasmatic nuclei (SCN) in the hypothalamus, which are primarily entrained by light detected by the retina. The SCN receives input from intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin, but also receive input from rods and cones. In turn, ipRGCs mediate a range of non-image forming responses to light including circadian entrainment and the pupillary light response (PLR)...
December 27, 2016: Human Molecular Genetics
https://www.readbyqxmd.com/read/28013393/ngf-anti-vegf-combined-exposure-protects-rcs-retinal-cells-and-photoreceptors-that-underwent-a-local-worsening-of-inflammation
#12
Maria Luisa Rocco, Bijorn Omar Balzamino, Graziana Esposito, Carla Petrella, Luigi Aloe, Alessandra Micera
PURPOSE: Our previous study highlighted the potential nerve growth factor (NGF) effect on damaged photoreceptors from a rat model of spontaneous Retinitis Pigmentosa (RP). Herein, we tested the combined NGF/anti-vascular endothelial growth factor (αVEGF) effect on cultured retinal cells isolated from Royal College of Surgeons (RCS) rats receiving an intravitreal VEGF injection (iv-VEGF) to exacerbate retinal inflammation/neovascularization. METHODS: RCS (n = 75) rats were equally grouped as untreated (n = 25), iv-saline (single saline intravitreal injection; n = 25) and iv-VEGF (single VEGF intravitreal injection; n = 25)...
December 24, 2016: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/28013033/differential-sensitivity-to-estrogen-induced-opsin-expression-in-two-poeciliid-freshwater-fish-species
#13
Caitlin N Friesen, Mary E Ramsey, Molly E Cummings
The sensory system shapes an individual's perception of the world, including social interactions with conspecifics, habitat selection, predator detection, and foraging behavior. Sensory signaling can be modulated by steroid hormones, making these processes particularly vulnerable to environmental perturbations. Here we examine the influence of exogenous estrogen manipulation on the visual physiology of female western mosquitofish (Gambusia affinis) and sailfin mollies (Poecilia latipinna), two poeciliid species that inhabit freshwater environments across the southern United States...
December 21, 2016: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28003732/regulation-of-photoreceptor-gene-transcription-via-a-highly-conserved-transcriptional-regulatory-element-by-vsx-gene-products
#14
Yi Pan, Daniel F Comiskey, Lisa E Kelly, Dawn S Chandler, Heithem M El-Hodiri
PURPOSE: The photoreceptor conserved element-1 (PCE-1) sequence is found in the transcriptional regulatory regions of many genes expressed in photoreceptors. The retinal homeobox (Rx or Rax) gene product functions by binding to PCE-1 sites. However, other transcriptional regulators have also been reported to bind to PCE-1. One of these, vsx2, is expressed in retinal progenitor and bipolar cells. The purpose of this study is to identify Xenopus laevis vsx gene products and characterize vsx gene product expression and function with respect to the PCE-1 site...
2016: Molecular Vision
https://www.readbyqxmd.com/read/27995922/lack-of-evidence-for-phase-only-control-of-retinal-photoisomerization-in-the-strict-one-photon-limit
#15
M Liebel, P Kukura
The concept of shaping electric fields to steer light-induced processes coherently has fascinated scientists for decades. Despite early theoretical considerations that ruled out one-photon coherent control (CC), several experimental studies reported that molecular responses are sensitive to the shape of the excitation field in the weak-field limit. These observations were largely attributed to the presence of rapid-decay channels, but experimental verification is lacking. Here, we test this hypothesis by investigating the degree of achievable control over the photoisomerization of the retinal protonated Schiff-base in bacteriorhodopsin, isorhodopsin and rhodopsin, all of which exhibit similar chromophores but different isomerization yields and excited-state lifetimes...
January 2017: Nature Chemistry
https://www.readbyqxmd.com/read/27993717/mapping-transmembrane-residues-of-proteinase-activated-receptor-2-par2-that-influence-ligand-modulated-calcium-signaling
#16
J Y Suen, M N Adams, J Lim, P K Madala, W Xu, A Cotterell, Y He, Mei-Kwan Yau, J D Hooper, D P Fairlie
Proteinase-activated receptor 2 (PAR2) is a G protein-coupled receptor involved in metabolism, inflammation, and cancers. It is activated by proteolysis, which exposes a nascent N-terminal sequence that becomes a tethered agonist. Short synthetic peptides corresponding to this sequence also activate PAR2, while small organic molecules show promising PAR2 antagonism. Developing PAR2 ligands into pharmaceuticals is hindered by a lack of knowledge of how synthetic ligands interact with and differentially modulate PAR2...
December 16, 2016: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
https://www.readbyqxmd.com/read/27979298/development-of-the-method-for-identification-of-selected-populations-of-torpedo-scad-megalaspis-cordyla-linnaeus-1758-using-microsatellite-dna-analyses-celfish-project-part-4
#17
Kempter Jolanta, Kielpinski Maciej, Panicz Remigiusz, Kaja Prüffer, Keszka Sławomir
Catch and consumption of torpedo scad (Megalaspis cordyla) over the western Indian Ocean, but also the western Pacific from Japan to Australia is constantly increasing. Taking into account the degree of exploitation and missing information on the population structure of torpedo scad stocks it is crucial to provide population data. The analysis included individuals obtained in 2012 and 2013 from local markets in Madagascar, Tanzania, Vietnam and Cambodia and after successful DNA extraction fragment of the nuclear rhodopsin gene (RH1) and 9 microsatellite regions (SSRs) were amplified and analysed...
April 15, 2017: Food Chemistry
https://www.readbyqxmd.com/read/27974638/untangling-ciliary-access-and-enrichment-of-two-rhodopsin-like-receptors-using-quantitative-fluorescence-microscopy-reveals-cell-specific-sorting-pathways
#18
Ivayla I Geneva, Han Yen Tan, Peter D Calvert
Resolution limitations of optical systems are major obstacles for determining if proteins are enriched within cell compartments. Here we employ an approach to determine the degree of membrane protein ciliary enrichment that quantitatively accounts for the differences in sampling of the ciliary and apical membranes inherent to confocal microscopes. Theory shows that cilia will appear more than threefold brighter than the surrounding apical membrane when the densities of fluorescently labeled proteins are the same, thus providing a benchmark for ciliary enrichment...
December 14, 2016: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/27966487/expressions-of-visual-pigments-and-synaptic-proteins-in-neonatal-chick-retina-exposed-to-light-of-variable-photoperiods
#19
Kumar Abhiram Jha, Tapas C Nag, Shashi Wadhwa, Tara Sankar Roy
Light causes damage to the retina, which is one of the supposed factors for age-related macular degeneration in human. Some animal species show drastic retinal changes when exposed to intense light (e.g. albino rats). Although birds have a pigmented retina, few reports indicated its susceptibility to light damage. To know how light influences a cone-dominated retina (as is the case with human), we examined the effects of moderate light intensity on the retina of white Leghorn chicks (Gallus g. domesticus). The newly hatched chicks were initially acclimatized at 500 lux for 7 days in 12 h light: 12 h dark cycles (12L:12D)...
December 2016: Journal of Biosciences
https://www.readbyqxmd.com/read/27965090/overexpression-of-mir-183-96-182-triggers-neuronal-cell-fate-in-human-retinal-pigment-epithelial-hrpe-cells-in-culture
#20
Maliheh Davari, Zahra-Soheila Soheili, Shahram Samiei, Zohreh Sharifi, Ehsan Ranaei Pirmardan
miR-183 cluster, composed of miR-183/-96/-182 genes, is highly expressed in the adult retina, particularly in photoreceptors. It involves in development, maturation and normal function of neuroretina. Ectopic overexpression of miR-183/-96/-182 genes was performed to assess reprogramming of hRPE cells. They were amplified from genomic DNA and cloned independently or in tandem configuration into pAAV.MCS vector. hRPE cells were then transfected with the recombinant constructs. Real-Time PCR was performed to measure the expression levels of miR-183/-96/-182 and that of several retina-specific neuronal genes such as OTX2, NRL, PDC and DCT...
December 10, 2016: Biochemical and Biophysical Research Communications
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