38 research outputs found

    Zebrafish Behavioral Profiling Links Drugs to Biological Targets and Rest/Wake Regulation

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    A major obstacle for the discovery of psychoactive drugs is the inability to predict how small molecules will alter complex behaviors. We report the development and application of a high-throughput, quantitative screen for drugs that alter the behavior of larval zebrafish. We found that the multidimensional nature of observed phenotypes enabled the hierarchical clustering of molecules according to shared behaviors. Behavioral profiling revealed conserved functions of psychotropic molecules and predicted the mechanisms of action of poorly characterized compounds. In addition, behavioral profiling implicated new factors such as ether-a-go-go–related gene (ERG) potassium channels and immunomodulators in the control of rest and locomotor activity. These results demonstrate the power of high-throughput behavioral profiling in zebrafish to discover and characterize psychotropic drugs and to dissect the pharmacology of complex behaviors

    Photochemical activation of TRPA1 channels in neurons and animals

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    Optogenetics is a powerful research tool because it enables high-resolution optical control of neuronal activity. However, current optogenetic approaches are limited to transgenic systems expressing microbial opsins and other exogenous photoreceptors. Here, we identify optovin, a small molecule that enables repeated photoactivation of motor behaviors in wild type animals. Surprisingly, optovin's behavioral effects are not visually mediated. Rather, photodetection is performed by sensory neurons expressing the cation channel TRPA1. TRPA1 is both necessary and sufficient for the optovin response. Optovin activates human TRPA1 via structure-dependent photochemical reactions with redox-sensitive cysteine residues. In animals with severed spinal cords, optovin treatment enables control of motor activity in the paralyzed extremities by localized illumination. These studies identify a light-based strategy for controlling endogenous TRPA1 receptors in vivo, with potential clinical and research applications in non-transgenic animals, including humans

    Chemical informatics and target identification in a zebrafish phenotypic screen

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    Target identification is a core challenge in chemical genetics. Here we use chemical similarity to predict computationally the targets of 586 compounds active in a zebrafish behavioral assay. Of 20 predictions tested, 11 had activities ranging from 1 to 10,000nM on the predicted targets. The role of two of these targets was tested in the original zebrafish phenotype. Prediction of targets from chemotype is rapid and may be generally applicable

    DISC1 at 10: connecting psychiatric genetics and neuroscience

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    Psychiatric genetics research, as exemplified by the DISC1 gene, aspires to inform on mental health etiology and to suggest improved strategies for intervention. DISC1 was discovered in 2000 through the molecular cloning of a chromosomal translocation that segregated with a spectrum of major mental illnesses in a single large Scottish family. Through in vitro experiments and mouse models, DISC1 has been firmly established as a genetic risk factor for a spectrum of psychiatric illness. As a consequence of its protein scaffold function, the DISC1 protein impacts on many aspects of brain function, impacting both neurosignalling and neurodevelopment. DISC1 is a pathfinder for understanding psychopathology, brain development, signaling and circuitry. Though much remains to be learnt and understood, potential targets for drug development are starting to emerge, and in this review, we will discuss the 10 years of research that has helped us understand key roles of DISC1 in psychiatric disease

    Apoptotic Cells Are Cleared by Directional Migration and elmo1- Dependent Macrophage Engulfment

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    SummaryApoptotic cell death is essential for development and tissue homeostasis [1, 2]. Failure to clear apoptotic cells can ultimately cause inflammation and autoimmunity [3, 4]. Apoptosis has primarily been studied by staining of fixed tissue sections, and a clear understanding of the behavior of apoptotic cells in living tissue has been elusive. Here, we use a newly developed technique [5] to track apoptotic cells in real time as they emerge and are cleared from the zebrafish brain. We find that apoptotic cells are remarkably motile, frequently migrating several cell diameters to the periphery of living tissues. F-actin remodeling occurs in surrounding cells, but also within the apoptotic cells themselves, suggesting a cell-autonomous component of motility. During the first 2 days of development, engulfment is rare, and most apoptotic cells lyse at the brain periphery. By 3 days postfertilization, most cell corpses are rapidly engulfed by macrophages. This engulfment requires the guanine nucleotide exchange factor elmo1. In elmo1-deficient macrophages, engulfment is rare and may occur through macropinocytosis rather than directed engulfment. These findings suggest that clearance of apoptotic cells in living vertebrates is accomplished by the combined actions of apoptotic cell migration and elmo1-dependent macrophage engulfment

    Leveraging Large-scale Behavioral Profiling in Zebrafish to Explore Neuroactive Polypharmacology

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    Many psychiatric drugs modulate the nervous system through multitarget mechanisms. However, systematic identification of multitarget compounds has been difficult using traditional in vitro screening assays. New approaches to phenotypic profiling in zebrafish can help researchers identify novel compounds with complex polypharmacology. For example, large-scale behavior-based chemical screens can rapidly identify large numbers of structurally diverse and phenotype-related compounds. Once these compounds have been identified, a systems-level analysis of their structures may help to identify statistically enriched target pathways. Together, systematic behavioral profiling and multitarget predictions may help researchers identify new behavior-modifying pathways and CNS therapeutics

    Solitary fish hit rock bottom

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    Live imaging of apoptotic cells in zebrafish

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    Many debilitating diseases, including neurodegenerative diseases, involve apoptosis. Several methods have been developed for visualizing apoptotic cells in vitro or in fixed tissues, but few tools are available for visualizing apoptotic cells in live animals. Here we describe a genetically encoded fluorescent reporter protein that labels apoptotic cells in live zebrafish embryos. During apoptosis, the phospholipid phosphatidylserine (PS) is exposed on the outer leaflet of the plasma membrane. The calcium-dependent protein Annexin V (A5) binds PS with high affinity, and biochemically purified, fluorescently labeled A5 probes have been widely used to detect apoptosis in vitro. Here we show that secreted A5 fused to yellow fluorescent protein specifically labels apoptotic cells in living zebrafish. We use this fluorescent probe to characterize patterns of apoptosis in living zebrafish larvae and to visualize neuronal cell death at single-cell resolution in vivo.—Van Ham, T. J., Mapes, J., Kokel, D., Peterson, R. T. Live imaging of apoptotic cells in zebrafish
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