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Channelrhodopsin

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https://www.readbyqxmd.com/read/28442946/optogenetic-rescue-of-locomotor-dysfunction-and-dopaminergic-degeneration-caused-by-alpha-synuclein-and-eko-genes
#1
Cheng Qi, Scott Varga, Soo-Jin Oh, C Justin Lee, Daewoo Lee
α-Synuclein (α-Syn) is a small presynaptic protein and its mutant forms (e.g. A53T) are known to be directly associated with Parkinson's disease (PD). Pathophysiological mechanisms underlying α-Syn-mediated neurodegeneration in PD still remain to be explored. However, several studies strongly support that overexpression of mutant α-Syn causes reduced release of dopamine (DA) in the brain, and contributes to motor deficits in PD. Using a favorable genetic model Drosophila larva, we examined whether reduced DA release is enough to induce key PD symptoms (i...
April 2017: Experimental Neurobiology
https://www.readbyqxmd.com/read/28435858/flexible-and-stretchable-nanowire-coated-fibers-for-optoelectronic-probing-of-spinal-cord-circuits
#2
Chi Lu, Seongjun Park, Thomas J Richner, Alexander Derry, Imogen Brown, Chong Hou, Siyuan Rao, Jeewoo Kang, Chet T Mortiz, Yoel Fink, Polina Anikeeva
Studies of neural pathways that contribute to loss and recovery of function following paralyzing spinal cord injury require devices for modulating and recording electrophysiological activity in specific neurons. These devices must be sufficiently flexible to match the low elastic modulus of neural tissue and to withstand repeated strains experienced by the spinal cord during normal movement. We report flexible, stretchable probes consisting of thermally drawn polymer fibers coated with micrometer-thick conductive meshes of silver nanowires...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28431249/macrophages-facilitate-electrical-conduction-in-the-heart
#3
Maarten Hulsmans, Sebastian Clauss, Ling Xiao, Aaron D Aguirre, Kevin R King, Alan Hanley, William J Hucker, Eike M Wülfers, Gunnar Seemann, Gabriel Courties, Yoshiko Iwamoto, Yuan Sun, Andrej J Savol, Hendrik B Sager, Kory J Lavine, Gregory A Fishbein, Diane E Capen, Nicolas Da Silva, Lucile Miquerol, Hiroko Wakimoto, Christine E Seidman, Jonathan G Seidman, Ruslan I Sadreyev, Kamila Naxerova, Richard N Mitchell, Dennis Brown, Peter Libby, Ralph Weissleder, Filip K Swirski, Peter Kohl, Claudio Vinegoni, David J Milan, Patrick T Ellinor, Matthias Nahrendorf
Organ-specific functions of tissue-resident macrophages in the steady-state heart are unknown. Here, we show that cardiac macrophages facilitate electrical conduction through the distal atrioventricular node, where conducting cells densely intersperse with elongated macrophages expressing connexin 43. When coupled to spontaneously beating cardiomyocytes via connexin-43-containing gap junctions, cardiac macrophages have a negative resting membrane potential and depolarize in synchrony with cardiomyocytes. Conversely, macrophages render the resting membrane potential of cardiomyocytes more positive and, according to computational modeling, accelerate their repolarization...
April 20, 2017: Cell
https://www.readbyqxmd.com/read/28409086/kinetic-characteristics-of-chimeric-channelrhodopsins-implicate-the-molecular-identity-involved-in-desensitization
#4
Alemeh Zamani, Shigeo Sakuragi, Toru Ishizuka, Hiromu Yawo
Channelrhodopsin (ChR)-1 and ChR2 were the first-identified members of ChRs which are a growing subfamily of microbial-type rhodopsins. Light absorption drives the generation of a photocurrent in cell membranes expressing ChR2. However, the photocurrent amplitude attenuates and becomes steady-state during prolonged irradiation. This process, called desensitization or inactivation, has been attributed to the accumulation of intermediates less conductive to cations. Here we provided evidence that the dark-adapted (DA) photocurrent before desensitization is kinetically different from the light-adapted (LA) one after desensitization, that is, the deceleration of both basal-to-conductive and conductive-to-basal transitions...
2017: Biophysics and Physicobiology
https://www.readbyqxmd.com/read/28395022/optogenetic-manipulation-of-anatomical-re-entry-by-light-guided-generation-of-a-reversible-local-conduction-block
#5
Masaya Watanabe, Iolanda Feola, Rupamanjari Majumder, Wanchana Jangsangthong, Alexander S Teplenin, Dirk L Ypey, Martin J Schalij, Katja Zeppenfeld, Antoine A F de Vries, Daniël A Pijnappels
Aims: Anatomical re-entry is an important mechanism of ventricular tachycardia, characterized by circular electrical propagation in a fixed pathway. It's current investigative and therapeutic approaches are non-biological, rather unspecific (drugs), traumatizing (electrical shocks), or irreversible (ablation). Optogenetics is a new biological technique that allows reversible modulation of electrical function with unmatched spatiotemporal precision using light-gated ion channels. We therefore investigated optogenetic manipulation of anatomical re-entry in ventricular cardiac tissue...
March 1, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28381675/alternative-formation-of-red-shifted-channelrhodopsins-noncovalent-incorporation-with-retinal-based-enamine-type-schiff-bases-and-mutated-channelopsin
#6
Takashi Okitsu, Take Matsuyama, Takahiro Yamashita, Toru Ishizuka, Hiromu Yawo, Yasushi Imamoto, Yoshinori Shichida, Akimori Wada
Red-shifted channelrhodopsins (ChRs) are attractive for optogenetic tools. We developed a new type of red-shifted ChRs that utilized noncovalent incorporation of retinal and 3,4-dehydroretinal-based enamine-type Schiff bases and mutated channelopsin, C1C2-K296G. These ChRs exhibited absorption maxima that were shifted 10-30 nm toward longer wavelengths than that of C1C2-ChR regenerated with all-trans-retinal.
2017: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/28380331/near-infrared-fluorescent-protein-irfp713-as-a-reporter-protein-for-optogenetic-vectors-a-transgenic-cre-reporter-rat-and-other-neuronal-studies
#7
Christopher T Richie, Leslie R Whitaker, Keith W Whitaker, Julie Necarsulmer, Heather A Baldwin, Yajun Zhang, Lowella Fortuno, Josh J Hinkle, Pyry Koivula, Mark J Henderson, Wenzhi Sun, Kai Wang, Jeffrey C Smith, Jim Pickel, Na Ji, Bruce T Hope, Brandon K Harvey
BACKGROUND: The use of genetically-encoded fluorescent reporters is essential for the identification and observation of cells that express transgenic modulatory proteins. Near-infrared (NIR) fluorescent proteins have superior light penetration through biological tissue, but are not yet widely adopted. NEW METHOD: Using the near-infrared fluorescent protein, iRFP713, improves the imaging resolution in thick tissue sections or the intact brain due to the reduced light-scattering at the longer, NIR wavelengths used to image the protein...
April 2, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28355544/complex-photochemistry-within-the-green-absorbing-channelrhodopsin-reachr
#8
Benjamin S Krause, Christiane Grimm, Joel C D Kaufmann, Franziska Schneider, Thomas P Sakmar, Franz J Bartl, Peter Hegemann
Channelrhodopsins (ChRs) are light-activated ion channels widely employed for photostimulation of excitable cells. This study focuses on ReaChR, a chimeric ChR variant with optimal properties for optogenetic applications. We combined electrophysiological recordings with infrared and UV-visible spectroscopic measurements to investigate photocurrents and photochemical properties of ReaChR. Our data imply that ReaChR is green-light activated (λmax = 532 nm) with a non-rhodopsin-like action spectrum peaking at 610 nm for stationary photocurrents...
March 28, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28350445/structural-changes-in-an-anion-channelrhodopsin-formation-of-the-k-and-l-intermediates-at-80-k
#9
Adrian Yi, Hai Li, Natalia Mamaeva, Roberto E Fernandez De Cordoba, Johan Lugtenburg, Willem J DeGrip, John L Spudich, Kenneth J Rothschild
A recently discovered natural family of light-gated anion channelrhodopsins (ACRs) from cryptophyte algae provides an effective means of optogenetically silencing neurons. The most extensively studied ACR is from Guillardia theta (GtACR1). Earlier studies of GtACR1 have established a correlation between formation of a blue-shifted L-like intermediate and the anion channel "open" state. To study structural changes of GtACR1 in the K and L intermediates of the photocycle, a combination of low-temperature Fourier transform infrared (FTIR) and ultraviolet-visible absorption difference spectroscopy was used along with stable-isotope retinal labeling and site-directed mutagenesis...
April 10, 2017: Biochemistry
https://www.readbyqxmd.com/read/28325790/dopamine-terminals-from-the-ventral-tegmental-area-gate-intrinsic-inhibition-in-the-prefrontal-cortex
#10
William C Buchta, Stephen V Mahler, Benjamin Harlan, Gary S Aston-Jones, Arthur C Riegel
Spike frequency adaptation (SFA or accommodation) and calcium-activated potassium channels that underlie after-hyperpolarization potentials (AHP) regulate repetitive firing of neurons. Precisely how neuromodulators such as dopamine from the ventral tegmental area (VTA) regulate SFA and AHP (together referred to as intrinsic inhibition) in the prefrontal cortex (PFC) remains unclear. Using whole cell electrophysiology, we measured intrinsic inhibition in prelimbic (PL) layer 5 pyramidal cells of male adult rats...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28320275/optogenetic-stimulation-increases-level-of-antiapoptotic-protein-bcl-xl-in-neurons
#11
D A Lanshakov, U S Drozd, N N Dygalo
The antiapoptotic protein Bcl-xL is associated with several neuroplastic processes such as formation of synapses, regulation of spontaneous and evoked synaptic responses, and release of neurotransmitters. Dependence of expression on activity of neurons is characteristic for many proteins participating in regulation of neuroplasticity. Whether such property is exhibited by the Bcl-xL protein was analyzed using in vivo optogenetic stimulation of hippocampal glutamatergic neurons expressing channelrhodopsin ChR2H134 under CAMKIIa promoter in the adeno-associated viral vector, followed by immunohistochemical determination of the level of Bcl-xL protein in these neurons and surrounding cells...
March 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28302720/adjacent-channelrhodopsin-2-residues-within-transmembranes-2-and-7-regulate-cation-selectivity-and-distribution-of-the-two-open-states
#12
Ryan Richards, Robert E Dempski
Channelrhodopsin-2 (ChR2) is a light-activated channel that can conduct cations of multiple valencies down the electrochemical gradient. Under continuous light exposure, ChR2 transitions from a high conducting open state (O1) to a low conducting open state (O2) with differing ion selectivity. The molecular basis for the O1 to O2 transition and how ChR2 modulates selectivity between states is currently unresolved. To this end, we used steered molecular dynamics, electrophysiology, and kinetic modeling to identify residues that contribute to gating and selectivity in discrete open states...
March 16, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28301742/microbial-rhodopsins-diversity-mechanisms-and-optogenetic-applications
#13
Elena G Govorunova, Oleg A Sineshchekov, Hai Li, John L Spudich
Microbial rhodopsins are a family of photoactive retinylidene proteins widespread throughout the microbial world. They are notable for their diversity of function, using variations of a shared seven-transmembrane helix design and similar photochemical reactions to carry out distinctly different light-driven energy and sensory transduction processes. Their study has contributed to our understanding of how evolution modifies protein scaffolds to create new protein chemistry, and their use as tools to control membrane potential with light is fundamental to optogenetics for research and clinical applications...
March 9, 2017: Annual Review of Biochemistry
https://www.readbyqxmd.com/read/28298301/in-vivo-optogenetic-activation-of-nav1-8-cutaneous-nociceptors-and-their-responses-to-natural-stimuli
#14
Megan L Uhelski, Daniel J Bruce, Philippe Seguela, George L Wilcox, Donald A Simone
Optogenetic methods utilizing expression of the light-sensitive protein channelrhodopsin-2 (ChR2) in neurons have enabled selective activation of specific subtypes or groups of neurons to determine their functions. Using a transgenic mouse model in which neurons natively expressing Nav1.8, a tetrodotoxin-resistant voltage-gated sodium channel, also express the light-gated channel ChR2, we have been able to determine the functional properties of Nav1.8-expressing cutaneous nociceptors of the glabrous skin in vivo...
March 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28297653/atomistic-study-of-intramolecular-interactions-in-the-closed-state-channelrhodopsin-chimera-c1c2
#15
Monika R VanGordon, Gaurav Gyawali, Steven W Rick, Susan B Rempe
Channelrhodopsins (ChR1 and ChR2) are light-activated ion channels that enable photomobility of microalgae from the genus Chlamydomonas. Despite common use of ChR2 in optogenetics for selective control and monitoring of individual neurons in living tissue, the protein structures remain unresolved. Instead, a crystal structure of the ChR chimera (C1C2), an engineered combination of helices I-V from ChR1, without its C-terminus, and helices VI-VII from ChR2, is used as a template for ChR2 structure prediction...
March 14, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28288335/how-to-control-cyclic-nucleotide-signaling-by-light
#16
REVIEW
Vera Jansen, Jan F Jikeli, Dagmar Wachten
Optogenetics allows to non-invasively manipulate cellular functions with spatio-temporal precision by combining genetic engineering with the control of protein function by light. Since the discovery of channelrhodopsin has pioneered the field, the optogenetic toolkit has been ever expanding and allows now not only to control neuronal activity by light, but rather a multitude of other cellular functions. One important application that has been established in recent years is the light-dependent control of second messenger signaling...
March 10, 2017: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/28283661/structure-guided-schema-recombination-generates-diverse-chimeric-channelrhodopsins
#17
Claire N Bedbrook, Austin J Rice, Kevin K Yang, Xiaozhe Ding, Siyuan Chen, Emily M LeProust, Viviana Gradinaru, Frances H Arnold
Integral membrane proteins (MPs) are key engineering targets due to their critical roles in regulating cell function. In engineering MPs, it can be extremely challenging to retain membrane localization capability while changing other desired properties. We have used structure-guided SCHEMA recombination to create a large set of functionally diverse chimeras from three sequence-diverse channelrhodopsins (ChRs). We chose 218 ChR chimeras from two SCHEMA libraries and assayed them for expression and plasma membrane localization in human embryonic kidney cells...
March 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28271037/cholinergic-neurons-in-the-dorsomedial-hypothalamus-regulate-food-intake
#18
Jae Hoon Jeong, Dong Kun Lee, Young-Hwan Jo
OBJECTIVE: Central cholinergic neural circuits play a role in the regulation of feeding behavior. The dorsomedial hypothalamus (DMH) is considered the appetite-stimulating center and contains cholinergic neurons. Here, we study the role of DMH cholinergic neurons in the control of food intake. METHODS: To selectively stimulate DMH cholinergic neurons, we expressed stimulatory designer receptors exclusively activated by designer drugs (DREADDs) and channelrhodopsins in DMH cholinergic neurons by injection of adeno-associated virus (AAV) vectors into the DMH of choline acetyltransferase (ChAT)-IRES-Cre mice...
March 2017: Molecular Metabolism
https://www.readbyqxmd.com/read/28269273/efficient-assembly-of-multi-color-fiberless-optoelectrodes-with-on-board-light-sources-for-neural-stimulation-and-recording
#19
K Kampasi, J Seymour, E Stark, G Buzsaki, K D Wise, E Yoon
Fiberless optoelectrodes are an emerging tool to enable brain circuit mapping by providing precise optical modulation and electrical monitoring of many neurons. While optoelectrodes having an on-board light source offer compact and optically efficient device solutions, many of them fail to provide robust thermal and electrical design to fully exploit the recording capabilities of the device. In this work, we present a novel fiberless multicolor optoelectrode solution, which meets the optical and thermal design requirements of an in vivo neural optoelectrode and offers potential for low-noise neural recording...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28256618/the-expanding-family-of-natural-anion-channelrhodopsins-reveals-large-variations-in-kinetics-conductance-and-spectral-sensitivity
#20
Elena G Govorunova, Oleg A Sineshchekov, Elsa M Rodarte, Roger Janz, Olivier Morelle, Michael Melkonian, Gane K-S Wong, John L Spudich
Natural anion channelrhodopsins (ACRs) discovered in the cryptophyte alga Guillardia theta generate large hyperpolarizing currents at membrane potentials above the Nernst equilibrium potential for Cl(-) and thus can be used as efficient inhibitory tools for optogenetics. We have identified and characterized new ACR homologs in different cryptophyte species, showing that all of them are anion-selective, and thus expanded this protein family to 20 functionally confirmed members. Sequence comparison of natural ACRs and engineered Cl(-)-conducting mutants of cation channelrhodopsins (CCRs) showed radical differences in their anion selectivity filters...
March 3, 2017: Scientific Reports
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