NIHRDataInsights/HRCSData huggingface dataset:
Title: Intrinsic plasticity of neuronal excitability in the auditory brainstem and neocortex: nitrergic signalling to voltage-gated potassium channels
Funder: Medical Research Council

Abstract: This project explores a new role for nitric oxide (NO) in brain signalling: as the mediator which adapts the intrinsic excitability of target neurons to their excitatory synaptic input. This is distinct from a role in synaptic plasticity but complimentary to it. Postsynaptic calcium influx through NMDAR or AMPAR activates neuronal nitric oxide synthase; NO activates the guanylyl cyclase receptor, generating cGMP and downstream signalling to potassium channels. We postulate that NO signalling increases Kv2 (and decrease Kv3) potassium currents through phosphorylation, so effecting trafficking to, or activity of channels in the plasma membrane. Increased current speeds repolarization giving short action potentials (AP) and enhanced high frequency firing. This homeostatic function maintains transmission during extreme signalling, which would otherwise result in AP failure. We will first explore the role of this conductance in protecting the cochlea from noise trauma by studying the neurones that give rise to the medial olivocochlear efferent projection (which express high levels of Kv2.2 and are located adjacent to an NO source in the superor olivary complex). Second we will explore how nitrergic signalling regulates Kv2.1 and Kv2.2 channels in the primary auditory cortex. Several reports have noted how glutamatergic synaptic inputs increase potassium currents in cortical neurons. We have evidence linking this to nitrergic signalling. We postulate that NO-mediated modulation of Kv2 is a general mechanism by which neuronal excitability is tuned to incoming synaptic activity. This research links the wealth of molecular evidence for NO involvement in neurological disease and neurodegeneration to the dynamic control of neuronal excitability; where NO is a trans-neuronal messenger by which synaptic input tunes the target to maintain effective physiological network function, and where aberrant cortical excitability underlies disease.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING
Health categories: NEUROLOGICAL
Title: Molecular control of corpus callosum development by Gli3
Funder: Medical Research Council

Abstract: Aim 1: Regulatory relationship between Gli3, Fgf8 and Wnts Our previous analyses showed that Gli3 interacts with Fgf8 and several Wnt genes during corticoseptal boundary (CSB) formation but the molecular basis for these interactions are unknown. We will investigate the regulatory relationships between Gli3, Fgf8 and Wnts during this process. Using electromobility shift and chromatin assays, we will determine whether the Ets transcription factors Etv4/5 bind to Gli3 and Wnt8b forebrain enhancers. We will use transgenic reporter gene assays to determine the functionality of these binding sites. Finally, we will incubate forebrain tissue in the presence of Fgf8 or of the Fgf signalling inhibitor SU 5402 to determine the effect of activating or inhibiting Fgf signalling, respectively, on Gli3 and Wnt8b expression. These analyses will test our hypothesis that Fgf signalling directly regulates Gli3 and Wnt8b expression in the forebrain. Aim 2. Identification of Gli3 regulated genes Gli3 controls development of the corpus callosum by regulating CSB formation. To identify Gli3 regulated genes during this process, we will conditionally inactivate Gli3 using an Emx1Cre driver line. At different time points after the start of Cre expression we will harvest cortical cells from either control or conditional mutant embryos. We will compare gene expression profiles between the two groups by RNA sequencing analyses. Bioinformatic analyses will group genes according to their temporal expression profiles (cluster analyses) and to their biological function (gene ontology analyses). We will determine the expression of candidate genes using in situ hybridization. In this way, we will identify genes which (i) are rapidly down-regulated after loss of Gli3 expression, (ii) are expressed in cortical progenitor cells and (iii) encode transcription factors, cell adhesion molecules or components of signalling pathways which likely play important roles in CSB formation.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Neuronal oscillations, attention, and normalization circuits
Funder: Medical Research Council

Abstract: Attention aids perceptual abilities. The neuronal underpinnings have been studied in detail, but often yielded conflicting results. Normalization models of attention reconcile many of these conflicts, with notable success in explaining the interactions between attention and stimulus contrast. Normalization models argue that attention affects neuronal processing by interacting with the stimulus and the suppressive drive: attention itself drives normalization. Neuronal responses are thus determined by the stimulus size and by the size of the attentional field. Normalization should thus affect different parameters of neuronal tuning functions in a manner similar to attention. The proposal cannot strictly be true, as normalization usually reduces neuronal activity, while attention increases it. However, across a neuronal population the effects of stimulus and attention driven normalization could still be correlated, even if the average sign of the effect differs between the two. Normalization models of attention equally predict that attention should increase oscillatory activity, as normalization circuits are a main driver of gamma frequency oscillations. Appropriate implementation of the normalization model of attention explains why attention has different effects on gamma oscillatory power in V1 than it does in V4, provided that stimulus size, size of the attentional focus, and receptive field size are accounted for. We aim to validate (or falsify) these predictions, by performing simultaneous recordings across cortical layers of V1 and V4, while stimulus size and the size of the attentional focus are parametrically varied, thereby assessing their effects on normalization circuits. We will gain a detailed understanding of the circuits involved in attention. We aim to understand why subtle task manipulations yield neuronal data sets, which so far make it impossible to propose a unified theory of the neuronal mechanisms underlying attention and cognition.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING
Health categories: NEUROLOGICAL
Title: Understanding the dopamine signals triggered directly by striatal acetylcholine: The circuits, their timing and the actions of addictive drugs
Funder: Medical Research Council

Abstract: Striatal dopamine (DA) critically participates in the regulation of motivation and action selection. Dysregulation of DA signaling underlies a variety of psychomotor disorders, including addiction and Parkinson's disease. Surprisingly however, our grasp of the neuronal mechanisms that govern DA transmission remains incomplete. Activity in midbrain DA neurons has long been assumed to be its principal driver, but we have obtained new evidence for a radical shift to this paradigm, requiring us to rethink the mechanisms that govern DA release, and in turn, DA function and dysfunction. Using an optogenetic strategy to light-activate striatal cholinergic interneurons (ChIs) that express channelrhodpsin2 (ChR2), and by detecting DA release at microelectrodes with subsecond resolution, we have identified that single action potentials in a population of ChIs triggers striatal DA release directly from DA axons by activating presynaptic nicotinic receptors (Threlfell et al, Neuron, in press). In addition, DA release was triggered by inputs to striatum from thalamus which coordinate ChI firing in vivo. Furthermore, ChI-evoked DA release overrode ascending activity in DA axons, suggesting that ChIs and their inputs might dominate as a trigger. These findings place ChIs central to our understanding of DA function and, potentially, dysfunction. It is imperative now to address key questions about how ChIs evoke DA release. We will exploit optogenetic technologies to incorporate established and new light-activated channelrhodopsins (ChR2 and C1V1) in DA neurons, ChIs and/or their inputs to identify: (1) which inputs recruit ChIs to drive DA transmission?; (2) how do dynamic repertoires of activity in ChIs and DA neurons interact to govern DA transmission?; and (3) are these mechanisms targeted by addictive drugs? These studies are critical if we are to improve our knowledge of DA system function, and gain new insights about strategies for future therapies in DA dysfunction.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING
Health categories: NEUROLOGICAL
Title: Using genetic variability in whole transcriptome expression in cells and tissues to understand the pathogenesis of Parkinson's and Alzheimer's disease
Funder: Medical Research Council

Abstract: The aim of this study is to determine the effect of genetic risk factors on whole transcriptome expression in brain regions and cell types most vulnerable to Parkinson's and Alzheimer's disease (PD and AD) in order to understand the pathogenic processes underlying these conditions. This project is inspired by the recent discovery of 15 new genetic risk variants for PD and 13 new loci for AD. However, knowing the genomic position of risk variants is not equivalent to knowing how they act in terms of the underlying molecular processes or where they act in terms of the regional or cellular location. We aim to address both these issues. Using control post-mortem human brain tissue originating from 150 individuals, we will use expression quantitative trait locus (eQTL) mapping and allele-specific expression (ASE) analysis to identify loci that both change disease risk and regulate the expression of specific gene transcripts within specific tissues/cells. We will conduct these studies within the tissues and cells most relevant to PD and AD, namely the substantia nigra, hippocampus, temporal cortex, dopaminergic neurons, CA1 neurons, pyramidal neurons and astrocytes. Existing exome sequencing and SNP array data will be combined with whole transcriptome RNA sequencing data generated on the Illumina HiSeq2000 platform for downstream analysis. These two types of information - genetic variation and transcript expression - will be used for eQTL mapping in tissues and ASE analysis in cells. In both cases the eQTLs identified will be annotated for disease-relevance in the first instance. All the data generated by this project will be publicly released as both raw data files for re-analysis and processed information suitable for non-expert users through NCBI's Gene Expression Omnibus repository and Phenotype-Genotype Integrator sites. Thus, we will generate novel disease-relevant findings and provide the neuroscience community with a world-class resource.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Parietal and cerebellar control of reaching and grasping and its dysfunction in developmental coordination disorder
Funder: Medical Research Council

Abstract: The parietal and motor cortices work with the cerebellum in planning, executing, and controlling reaching and grasping movements towards objects. In developmental coordination disorder (DCD), a neurodevelopmental disorder in the coordination of posture, gross, and fine arm and hand movements, the temporal and spatial control of reaching and grasping movements are some of the most impaired aspects of motor coordination. The leading hypothesis for the aetiology of DCD is an impairment of cerebellar function, but direct evidence is lacking. The proposed research will test the parietal-cerebellar hypothesis of DCD, and will also study in parallel the parietal-cerebellar control of reaching and grasping movements in healthy adults. The project will use motion tracking, electromyography, structural, metabolic, and functional neuroimaging, and transcranial magnetic stimulation to provide a multi-method test of the hypothesis. During grasping movements, error, inaccuracy, and target positions changes arise. The reaching movement must then be adapted on-line, to reduce the error, bringing the hand and target closer together. This on-line error correction process occurs for every movement, but takes some time. The most rapid movement corrections in humans begin at 90-120ms after an unexpected change in target object position, and consist first of a deceleration towards the initial target, then an acceleration towards the new target. Despite the robustness of this effect, the neural basis in humans is still debated, with only a handful of studies directly testing online control. In cats, lesions to the rubrospinal, tectospinal, propriospinal, and corticospinal tracts can delay online reaching corrections by 10-40ms, with the most rapid corrections mediated by cerebello-spinal pathways. Since some of the clearest deficits in DCD are incoordination of reaching and grasping, and delays in on-line control, this is an ideal model for testing the neural aetiology of DCD.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Novel strategies for promoting CNS repair through manipulation of FGF signalling and heparan sulphate proteoglycans
Funder: Medical Research Council

Abstract: After injury, the central nervous system (CNS) undergoes an astrocyte stress response characterized by reactive astrocytosis/proliferation and scar formation (resulting in a boundary around the injury site). This response is widely considered to be a major inhibitory mechanism for CNS repair. We discovered that astrocytes exhibit this stress response in vitro when in contact with Schwann cells (SCs) but not when in contact with olfactory ensheathing cells (OECs), even though both cell types are very similar antigenically, morphologically and in their ability to remyelinate axons with peripheral type myelin. This difference is due to factor(s) secreted by SCs but absent from OECs. SCs are regarded as strong candidates for glial transplantation to enhance CNS repair, because of ready availability from peripheral nerves, but suffer from the drawback of inducing these astrocytic reactions. Thus, approaches which resolve this problem would have considerable significance in potential therapeutic applications. We have recently defined the molecular mechanisms mediating this effect, revealing a crucial involvement of heparan sulphate proteoglycan (HSPG) regulation of fibroblast growth factor 9 signaling. Our data have, thus, uncovered a novel signaling axis that differentially regulates the astrocyte stress response by OECs compared with SCs. In the current proposal, we plan to exploit these new molecular insights to develop and test molecular interventions to control SC astrocytic responses, firstly in the in vitro model as a screening tool. Selected strategies will then be tested in a biologically relevant, medium through-put in vivo model of CNS cellular interaction involving glial cell transplantation. These studies will provide proof-of-concept for novel strategies to enhance CNS repair by manipulating the inhibitory environment induced after injury, and will be the essential prelude to subsequent translational research aimed at enhancing functional CNS repair.


Research activity codes: 5.2 CELLULAR AND GENE THERAPIES
Health categories: NEUROLOGICAL
Title: Exploring GABAAalpha2,3 receptor signalling as novel therapy for focal dystonias and peripheral neuropathies
Funder: Medical Research Council

Abstract: This is a series of proof of concept studies to establish the use of a novel, safe and orally bioavailable positive modulator of GABAAalpha2,3 receptor AZD7235 for new clinical indications on sensory and motor performance tasks in humans. Three cohorts of study participants will be studied in double blind, placebo controlled, 3-way cross-over studies: healthy volunteers, and patients with two neurological conditions representing the abnormal gain (primary focal dystonia) or loss (peripheral neuropathy) of somatosensory function. The rationale is to use enhanced central GABAAalpha2,3 receptor signalling to ameliorate conditions characterised by a loss of central GABAA receptor activity (dystonia) or to compensate centrally for a peripheral deficit (neuropathy). The expected outcomes include: 1.) Changes of short-interval intracortical inhibition (SICI), a sensitive neurophysiological biomarkers of GABAA receptor function in sensorimotor control of the CNS. 2.) Improvement in the performance of standardised skilled object manipulation tasks. 3.) Improvement in the performance of psychophysical tests of cutaneous mechanosensation of the hand The expected positive outcome will provide the rationale for future proof of principle studies in larger clinical cohorts and open the possibility for new therapeutic strategies in these difficult to treat conditions.


Research activity codes: 2.4 SURVEILLANCE AND DISTRIBUTION;6.1 PHARMACEUTICALS
Health categories: NEUROLOGICAL
Title: MICA- Evaluation of AZD1080 (GSK-3 inhibitor) in a preclinical mouse model of motor neuron disease (MND)
Funder: Medical Research Council

Abstract: Motor neurone disease (MND) is a devastating neurodegenerative disorder with rapid progression to death from neuromuscular respiratory failure in the majority of afflicted individuals. There is an urgent need for improved approaches to achieve neuroprotection in ALS. Aberrant over-expression and activation of glycogen synthase kinase 3 (GSK-3) is implicated in neurodegeneration in MND and several studies in animal models suggest inhibition of this pathway may be beneficial, however the compounds used are unselective and associated with side effects (lithium) or the studies were sub-optimal and so do not give a true reflection of the therapeutic potential of GSK-3 inhibitors in MND. The AstraZeneca compound, AZD1080 is a CNS-penetrating, potent and selective reversible inhibitor of GSK-3 which has been tested in 224 healthy volunteers in Phase I studies and shows PK profile commensurate with exposures observed in preclinical models of inhibition of Tau phosphorylation in the hippocampus. We have developed a preclinical mouse model and screening approach for candidate MND therapeutics which can provide rigorous, high quality data on a variety of readouts of motor neuron degeneration. We will use AZD1080 and our preclinical model to provide definitive information on the therapeutic potential of GSK-3 inhibition in MND with a view to further clinical development of AZD1080 in the human disease. In addition, recent in vitro data has shown that GSK-3 can promote degradation of Nrf2, a key regulator of cellular oxidative stress responses. We have identified compounds which activate this transcription factor, providing protection for motor neurones from oxidative stress. We will probe, in vivo, the importance of GSK-3 in regulating this pathway in our MND model using one of our Nrf2 activating molecules with AZD1080 to determine whether a combination of these compounds leads to a greater improvement in motor function than we have already achieved.


Research activity codes: 5.1 PHARMACEUTICALS
Health categories: NEUROLOGICAL
Title: Differentiation of GMP-grade human embryonic stem cells to midbrain dopaminergic neurons for transplantation
Funder: Medical Research Council

Abstract: Transplantation of fetal midbrain tissue to treat Parkinson's disease (PD) has demonstrated proof-of-concept that some patients can benefit from such grafts. An international multi-centre Framework 7 European clinical trial, TRANSEURO, is underway to re-visit fetal midbrain transplants and systematically address all protocol and procedural issues with the earlier clinical trials. There is a pressing need to resolve the critical questions of scaleable supply and quality of appropriate Good Manufacturing Practice (GMP) grade dopaminergic cells for any future widespread use in the treatment of PD. Replacing fetal midbrain tissue with midbrain dopaminergic (mDA) neurons differentiated from human embryonic stem cells (hESCs) is the most realistic solution to the cell source problem. We will modify and optimise a novel method to differentiate hESCs to mDA neurons, which relies on a developmental protocol based on floor plate specification. GMP-grade hESCs from multiple sources throughout the UK will be quantitatively assessed for efficiency of mDA differentiation. The best performing hESC line will be used to establish procedures to produce GMP-capable mDA preparations for transplantation. All experiments will be performed with research-grade reagents that have a suitable GMP-grade equivalent available. The mDA neuronal populations will be transplanted into two nude rat models of PD (i) a 6-hydroxydopamine lesion model and (ii) an adeno-associated virus-alpha-synuclein model. Graft survival, behavioural improvements, and absence of tumour formation will be assessed. This collaborative proposal will bring together expertise in pluripotent stem cell differentiation, pre-clinical models of PD, and the UK 's clinical-grade hESCs, with the ultimate aim of moving to first-in-human clinical trials.


Research activity codes: 5.2 CELLULAR AND GENE THERAPIES
Health categories: NEUROLOGICAL
Title: Analysing the cell biology of the Parkinson's Disease-linked missense mutation in the retromer VPS35 subunit.
Funder: Medical Research Council

Abstract: In sorting an array of cargoes, for example proteins, lipids, nutrients, and solutes, to a variety of cellular destinations, the endosomal network performs an essential function in regulating and fine-tuning numerous processes within the cell. Retromer complexes are evolutionarily conserved orchestrators of endosomal sorting. The canonical SNX-BAR-retromer is composed of a stable 'cargo-selective' trimer composed of VPS26, VPS29 and VPS35, and a 'membrane-deforming sub-complex' composed of a heterodimer of the sorting nexin (SNX)-Bin/Amphiphysin/Rvs (BAR) domain-containing proteins (SNX-BARs) SNX1 or SNX2 with SNX5 or SNX6. The non-canonical SNX3-retromer shares the VPS26:VPS29:VPS35 trimer but contains a distinct membrane-bound sub-complex composed of the non-BAR domain-containing SNX3. These endosomal sorting complexes regulate parallel endosome-to-TGN retrieval pathways and, in the case of the SNX-BAR-retromer, endosome-to-plasma membrane recycling. Recently a missense D620N mutation in VPS35 has been linked with late-onset, autosomal dominant Parkinson's Disease (PD). Although VPS35(D620N) cases show an earlier onset than commonly observed, they are otherwise similar to classic sporadic PD suggestive of considerable overlap in disease pathways. Elucidating not only the VPS35(D620N) mutation but more broadly the role of retromer in neuronal endosomal sorting, may ultimately lead to new insight into the causes of PD. Based on extensive preliminary data we shall test the following hypothesis: The underlying defect for patients with VPS35(D620N)-linked PD is an uncoupling of retromer-mediated cargo sorting from WASH-dependent actin polymerization, which is manifested as a decrease in the efficiency of processing of tubular profiles into isolated transport carriers, and a resultant defect in retromer-mediated endosomal sorting of neuronal cargo proteins, that include specific glucose transporters that normally function to suppress PD neuropathology.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL