NIHRDataInsights/HRCSData huggingface dataset:
Title: The role of Wnt signalling in synaptic maintenance
Funder: Medical Research Council

Abstract: Understanding the molecular mechanisms that regulate the formation, maintenance and function of synapses has been central for developing therapeutic approaches for the treatment of neurological conditions, nerve and brain injury as well as neurodegenerative diseases. In the last two decades a considerable progress has been made in the elucidation of the molecular mechanisms that control the formation of neuronal circuits. Our laboratory made a significant contribution to this field with the discovery that Wnt proteins regulate neuronal connectivity by inducing the formation of synapses in the central nervous system. More recently we found that Wnt signaling is also required for the maintenance of mature synapses. We found that Wnt blockade by Dkk1, a Wnt antagonist that specifically blocks canonical Wnt signalling, induces the disassembly of mature synapses in cultured neurons. We also found that Wnt signalling specifically regulates excitatory synapses. In this grant proposal we are taking an interdisciplinary approach to elucidate the function of Wnt signalling in synaptic maintenance, its mechanism and its contribution to animal behaviour. We will examine: 1) The role of Wnt signalling on synaptic maintenance. The effect of loss of Wnt function or Wnt blockage on the maintenance of synapses will be examined in hippocampal cultures and in the brain. Inducible transgenic expressing Dkk1 and the conditional Wnt7b mutant mice, in which Wnt signalling is specifically affected in the adult hippocampus, will be analysed. A combination of immunofluorescence approaches, electron microscopy and live cell imaging techniques will be used to establish the cellular steps leading to the disassembly of synapses upon the loss of Wnt signalling. 2) The signalling transduction pathways involved in Wnt-mediated synaptic maintenance. For this purpose, we will specifically examine the role of the canonical Wnt signalling pathway using gain and loss of function approaches. These studies will contribute to further elucidate the mechanisms that govern synaptic assembly and disassembly. 3) The contribution of Wnt signalling in synaptic transmission and plasticity in mature neurons. We will specifically examine the function of Wnt signalling in the maintenance of the proper ratio of excitatory to inhibitory synapses, and of silent synapses. Furthermore, we will test whether Wnt signalling regulates LTP and LTD in the hippocampus. 4) The function of Wnt signalling on the behaviour of young adult mice by analysing inducible transgenic mice expressing Dkk1 and conditional Wnt7b mutant mice.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Investigation of the reorganisation of language and verbal memory systems in chronic temporal lobe epilepsy.
Funder: Medical Research Council

Abstract: Aims: In healthy subjects: to determine, in this control group, the distributed systems engaged during speech comprehension and production. In patients with chronic TLE, with either a left- or right-lateralised focus: to determine changes in the processing of language, and the episodic memory processes engaged in parallel; in particular, to determine whether patients with left TLE show evidence of a ‘laterality shift‘ of these systems, or whether reorganisation is expressed as a change in the functional connectivity between cortical and sub-cortical regions, both within and between cerebral hemispheres. The absence of major aphasia following anterior temporal lobectomy to treat TLE has been interpreted as evidence that anterior temporal cortex has little role to play in speech comprehension and production. This contrasts with studies in patients with semantic dementia, and some functional imaging studies on normal subjects. My study will investigate the functional anatomy of speech comprehension and production, with emphasis on anterior and mesial temporal lobe structures, in patients with chronic TLE who have not undergone neurosurgery. In particular, it will assess whether reorganisation accompanies chronic focal temporal lobe epileptic activity, invalidating inferences about normal organisation drawn from the behavioural effects of anterior temporal lobectomy. In parallel, the study will investigate episodic verbal memory encoding and retrieval that accompanies speech comprehension and production. The MRI protocols and results will be of direct relevance to the pre-operative assessment of epileptic or tumour patients prior to neurosurgical intervention. I will recruit 20 healthy subjects and 30-40 patients with chronic temporal lobe epilepsy (left and right-lateralised foci). All groups will be matched, as closely as possible, for age, sex and I.Q. All subjects will undergo both anatomical (including diffusion tensor imaging to assess white matter integrity) and functional magnetic resonance imaging after comprehensive neuropsychological testing. I will use implicit speech comprehension and speech production as the activation tasks, with a range of baseline control conditions. Behavioural scores will be analysed using appropriate SPSS analyses. Anatomical and functional imaging scan data will be analysed using SPM5 (Wellcome Department of Cognitive Neurology) and FSL (FMRIB, Oxford) software. In addition to planned contrasts, the functional imaging data will be subjected to analyses of functional connectivity and voxel-based morphometry. Random effects statistical analyses will be performed both within and between groups.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Reversible stabilisation and translocation strategies for the study of neuronal PTEN in vitro and in vivo
Funder: Medical Research Council

Abstract: Recent work indicates that restricted loss of PTEN in neuronal populations in the forebrain of mice results in progressive macrocephaly and exuberant sprouting of neuronal processes. The appearance of enlarged neuronal soma and macrocephaly (both of which are indicative of specific forms of ASD in humans), together with the development of neurological symptoms that include deficits in social interaction, seizures and decreased learning, suggests that these mice may provide a direct causal link between PTEN deficiency and ASD. The project will consolidate and extend the use of novel tools that complement currently exploited gene targeting strategies by adding the potential to regulate PTEN in a specific, fast, reversible and tuneable manner. With these new tools, we propose: 1) to determine the function of nuclear PTEN in neurons. We will use a chemical-induced dimerization system in order to restrict PTEN to the nucleus or to exclude PTEN from the nucleus. We will monitor the activation status of PI3K signalling, but also PTEN-regulated, potentially PI3K independent signalling pathways. The results will be correlated with experiments that are aimed at investigating role of nuclear PTEN on the establishment and maintenance of proper neuronal morphology. We also propose: 2) to generate tuneable PTEN mice. These will permit conditional control over protein levels of PTEN in dependence of a synthetic ligand. We will combine the tuneable PTEN mouse with a specific CRE driver in order to evaluate the role of inactivating PI3K signalling on neuronal morphology of forebrain neurons in vivo. We will also create mice in which conditional PTEN loss will be directly coupled with the expression of our tuneable PTEN. This will allow us to address if progressive changes in the cortex and hippocampus of mice (as a consequence of loss of PTEN) can be antagonised by restoring PTEN. We will allow different time windows for neurons to be PTEN deficient, before re-installing PTEN and analyses by morphological and behavioural tests. This research is essential for the attempt to gain fundamental insights into the significance of PI3K signalling in the formation and maintenance of neuronal circuits, as well as into the degree of plasticity within specific neuronal connections that are important for normal learning and social behaviour. We believe that this research has, potentially, direct implications for the development and validation of pharmacological therapeutics for the treatment of various neurological disorders, including ASD.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING
Health categories: NEUROLOGICAL
Title: Regulation of synaptic inhibition by GABAA receptor trafficking under normal conditions and in neurological and neuropsy
Funder: Medical Research Council

Abstract: The activity of GABAA receptors (GABAARs)s at inhibitory synapses is critical for maintaining the correct balance between excitation and inhibition of neurons. The strength of inhibitory synapses, and thus neural information processing, can be modulated by altering the trafficking of GABAARs into or out of the postsynaptic membrane. Altered GABAAR activity and trafficking are also implicated in many neurological and psychiatric diseases including epilepsy, stroke, Huntington‘s disease, anxiety, drug addiction, depression and schizophrenia. Thus, understanding how the strength of inhibitory synapses is controlled by GABAAR trafficking is crucial for understanding how the brain works, and may also lead to the identification of therapeutic interventions in a wide range of diseases. Using novel imaging, molecular, cell biological and electrophysiological techniques, I will determine the molecular mechanisms that control GABAAR trafficking. I will focus on how covalent modification of GABAARs (e.g. by phosphorylation and ubiquitination) and interaction with GABAAR associated proteins (AP2, HAP1 and the novel ubiquitin ligase, Guapa) regulates surface receptor mobility (lateral diffusion and dwell time at synapses) and GABAAR trafficking to and from the membrane (exocytosis, endocytosis and degradation) to control inhibition under resting conditions, during neural activity, during homeostatic plasticity and in diseases like epilepsy. A major aim will be to develop novel imaging techniques to study receptor lateral diffusion and trafficking (such as receptor tracking with Quantum Dots) to study trafficking processes in intact tissues such as brain slices from animal models of neurological disease. A second major aim will be to determine if the pathological GABAAR internalization that occurs during status epilepticus, which leads to rapid resistance to drugs used to treat status, can be inhibited by targeting the GABAAR endocytic and degradation machineries. This could lead to novel therapeutic interventions for this devastating disease. A third major aim will be to determine if HAP1-dependent GABAAR trafficking is important for inhibitory homeostatic plasticity, to test whether this is disrupted by mutant huntingtin (which causes Huntington‘s disease) and to determine whether HAP1 function is regulated by the schizophrenia susceptibility genes DISC1 and dysbindin. This work will provide fundamental insights into the mechanisms that regulate the number of GABAA receptors at synapses normally and during synaptic plasticity, and may also lead to new information regarding the cell biology of a number of proteins critically implicated in neurological and psychiatric diseases.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: The Genetics and Pathophysiology of Spinocerebellar Degeneration
Funder: Medical Research Council

Abstract: Aims The purpose of this research is to build a genetic framework and establish the functional pathways that lead to spinocerebellar degeneration. My initial work will identify both the common as well as the rare genetic risk factors and disease modifiers of spinocerebellar ataxia. The effects on expression of these variants will be examined in normal cerebellar, affected lymphoblastoid and brain mRNA. Pathogenic and modifying variants and their interacting proteins will be further investigated with tissue culture and neuropathological approaches. My current MRC fellowship has been very successful, achieving 4/5 goals with 15 months to go. This has allowed me to develop techniques and establish important collaborations, such as the ataxia DNA and brain bank collection, thus laying the groundwork for future projects. Design and methodology This project incorporates a number of strategies. 1. Investigation of genetic variation in pure spinocerebellar ataxia (SCA) of unknown aetiology and the identification of genetic modifiers of the polyglutamine associated SCAs: (a) Genome wide association study (GWAS) in pure spinocerebellar ataxia. In a total of 1680 samples, structural changes, copy-number variation and disease associated SNPs will be identified. This will be replicated in a European/USA cohort. (b) GWAS to identify age-of-onset (AOO) modifiers of SCA1, 2, 3, 6 and 7 in 1255 SCA cases from the UK and EUROSCA. This data will be replicated in Huntington‘s disease through the funded Euro-HD-study and we have further access to Japanese/USA/Chinese and Australian SCA cohorts. (c) Deep sequencing for variants in the loci from 1(a) and (b) and for rare coding changes in candidate genes which include known ataxia genes, channel/inositol pathway genes, fly and yeast modifier screen genes. 2. Expression profiling: Many of the variants identified will be non coding and likely to act by altering gene expression. Analysing genome-wide cerebellar mRNA expression data will allow the identification of expression differences. 3. Functional investigation: Gene function and protein interactors will be investigated in affected lymphoblastoid/brain mRNA, transient or stable cell models and if a channel-gene is implicated we will collaborate with Hanna/ Schorge to perform channel electrophysiology. 4. Neuropathology: This resource has already proven vital to our research in the characterisation of neuropathological features and the investigation of interacting proteins. Opportunities A significant proportion of the genetic risk factors will be identified providing a framework of pathways to interrogate functionally. Defining these pathways will facilitate the identification of therapies and allow more effective trials by precise stratification of patient cohorts.


Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Analysis of deficits in presynaptic function in mouse models of Parkinson's disease
Funder: Medical Research Council

Abstract: Several lines of evidence from studies of murine disease models strongly suggest that defects in processes underlying neurotransmitter release at the synapse, most of which appear to converge on the synaptic vesicle cycle, may be very important in several forms of Parkinson‘s disease (PD), including both alpha-synucleinopathies and juvenile autosomal recessive types; however, as yet, a detailed study of these is lacking. I therefore plan to carry out a comprehensive characterisation of presynaptic release in relevant mouse models of PD using a variety of high-resolution real time imaging-based approaches which will also test specific hypotheses about the precise substrate of the deficits in the different model lines. Specifically, the experiments will focus on the use of fluorescent reporters of calcium transients and synaptic vesicle cycling in brain slice preparations and in transfected primary cultures of midbrain dopaminergic neurons. Attempts will be made to reverse observed deficits by overexpression of functionally relevant proteins. I further hypothesise that, via alterations in the cytoplasmic concentration of neurotransmitters, these deficits might specifically compromise the survival of dopaminergic neurons and thereby have a causative role in the development of Parkinsonian phenotypes. To test this, an extensive archive of randomly ENU-mutagenised mouse lines will be screened for those harbouring mutations predicted to result in similar deficits in presynaptic function, and these will then be re-derived, characterised and aged in order to assess whether there are effects on dopaminergic neuron survival and whether a PD-like phenotype develops. Overall, these studies could implicate a novel mechanism in a central role in PD pathogenesis, and provide an experimental basis on which to design a new generation of targeted therapies for PD.


Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: NEUROLOGICAL
Title: Diffusion tensor imaging in familial Alzheimer's disease: Longitudinal and cross-sectional studies of early change
Funder: Medical Research Council

Abstract: As increasing numbers of therapies promising disease modification in Alzheimer‘s disease (AD) undergo development, the need for reliable biomarkers has never been more relevant. Targeting therapies to the early stages of the disease where they are most likely to be effective, and monitoring their effect on the pathological process, demands sensitive markers of early manifestation and progression of disease. Although rare, familial Alzheimer‘s disease (FAD) provides the unique opportunity to carry out prospective longitudinal study of individuals who are cognitively normal but are destined to develop the disease. Diffusion imaging allows assessment of alterations in tissue microstructure which may be an early marker of pathological change. Diffusion tensor imaging (DTI) extends the modality to examine the integrity of white matter pathways and allows the assessment of connections between degenerating regions. It is now well established that grey matter losses and neuropsychological deficits are detectable many years prior to symptom onset in FAD mutation carriers. Degeneration of white matter tracts connecting these cortical areas and the concomitant effects of loss of connectivity have been less well studied, however there is evidence that these changes occur early. The aim of this study is to investigate markers of early change using DTI in presymptomatic individuals at risk of FAD and in individuals mildly affected by familial and sporadic AD. We will use serial volumetric MRI and diffusion imaging, together with clinical and neuropsychological assessments, to study presymptomatic FAD mutation carriers, mildly affected individuals with FAD and young-onset sporadic AD, and age-matched controls. We will combine volumetric imaging and DTI to assess the relative contributions to, and relationship between, grey and white matter damage. In the FAD cohort, we will also have the opportunity to compare these results with changes detectable on amyloid imaging through PET scanning using the C11-PIB ligand. In addition, we will, for the first time, look at longitudinal changes in diffusion and correlate these with changes in clinical and cognitive measures over time. Measurement of within-individual changes on imaging avoids some of the natural between-individual variability and may be a more sensitive and relevant marker of pathological change than a single assessment. This study will derive new imaging biomarkers for the detection of early change in AD, and provide more general insights into the pathobiology of neurodegenerative disease.


Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES
Health categories: NEUROLOGICAL
Title: Fragile X syndrome in development of the somatosensory cortex
Funder: Medical Research Council

Abstract: Fragile X syndrome (FXS) is the commonest genetically inherited form of mental retardation. Sufferers display impaired development of cognitive function including defects in sensory processing. Higher cognitive functions such as those affected by FXS are carried out in the cerebral cortex. I will use the rodent barrel cortex, a region which carries out sensory processing, as a model of cortical development, together with a genetic mouse model of FXS developed in Edinburgh, to establish the defects in development of synaptic and cellular physiology which lead to the symptoms of FXS. Multidisciplinary research on the barrel cortex system has shown that plastic changes in thalamocortical synapses, which can be studied using in vitro electrophysiology, are the same as the processes responsible for experience-dependent development of sensory processing. In adults this sensory processing allows input from the whiskers, which reaches the barrel cortex via synapses in the brainstem and thalamus, to determine the location, size and texture of objects detected by the whiskers. I have shown previously that long-term synaptic plasticity of excitatory transmission and developmental recruitment of a specific class of inhibitory interneuron act together to change a juvenile physiological phenotype in to a mature phenotype ideally suited to information processing. Disruption of these processes could lead to cognitive problems such as those seen in FXS. At present, however, it is unclear how these synaptic plasticity phenomena are induced in vivo and what role the juvenile physiological phenotype, including slow kainate receptor-mediated synaptic transmission, may have in this induction. The role of the other classes of inhibitory interneurons present in the barrel cortex is also unknown. I will use in vitro electrophysiology in the thalamocortical slice preparation to determine whether a prominent form of network activity recorded in juvenile barrel cortex in vivo, the spindle burst, is able to produce the depolarization needed to induce long-term synaptic plasticity. I will use kainate receptor knock-out mice to test the role of these receptors in spindle bursts and induction of plasticity. I will use mice which express GFP in interneurons (GAD-65 GFP mice) to elucidate which other classes of interneuron are recruited by physiologically relevant bursts of thalamic activity and how this affects the function of the network. Finally I will use a mouse model of FXS to show whether defects in these processes lead to mental retardation in FXS. Understanding these defects may lead to treatments for this condition.


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