Project acronym A-FRO
Project Actively Frozen - contextual modulation of freezing and its neuronal basis
Researcher (PI) Marta de Aragao Pacheco Moita
Host Institution (HI) FUNDACAO D. ANNA SOMMER CHAMPALIMAUD E DR. CARLOS MONTEZ CHAMPALIMAUD
Country Portugal
Call Details Consolidator Grant (CoG), LS5, ERC-2018-COG
Summary When faced with a threat, an animal must decide whether to freeze, reducing its chances of being noticed, or to flee to the safety of a refuge. Animals from fish to primates choose between these two alternatives when confronted by an attacking predator, a choice that largely depends on the context in which the threat occurs. Recent work has made strides identifying the pre-motor circuits, and their inputs, which control freezing behavior in rodents, but how contextual information is integrated to guide this choice is still far from understood. We recently found that fruit flies in response to visual looming stimuli, simulating a large object on collision course, make rapid freeze/flee choices that depend on the social and spatial environment, and the fly’s internal state. Further, identification of looming detector neurons was recently reported and we identified the descending command neurons, DNp09, responsible for freezing in the fly. Knowing the sensory input and descending output for looming-evoked freezing, two environmental factors that modulate its expression, and using a genetically tractable system affording the use of large sample sizes, places us in an unique position to understand how a information about a threat is integrated with cues from the environment to guide the choice of whether to freeze (our goal). To assess how social information impinges on the circuit for freezing, we will examine the sensory inputs and neuromodulators that mediate this process, mapping their connections to DNp09 neurons (Aim 1). We ask whether learning is required for the spatial modulation of freezing, which cues flies are using to discriminate different places and which brain circuits mediate this process (Aim 2). Finally, we will study how activity of DNp09 neurons drives freezing (Aim 3). This project will provide a comprehensive understanding of the mechanism of freezing and its modulation by the environment, from single neurons to behaviour.
Summary
When faced with a threat, an animal must decide whether to freeze, reducing its chances of being noticed, or to flee to the safety of a refuge. Animals from fish to primates choose between these two alternatives when confronted by an attacking predator, a choice that largely depends on the context in which the threat occurs. Recent work has made strides identifying the pre-motor circuits, and their inputs, which control freezing behavior in rodents, but how contextual information is integrated to guide this choice is still far from understood. We recently found that fruit flies in response to visual looming stimuli, simulating a large object on collision course, make rapid freeze/flee choices that depend on the social and spatial environment, and the fly’s internal state. Further, identification of looming detector neurons was recently reported and we identified the descending command neurons, DNp09, responsible for freezing in the fly. Knowing the sensory input and descending output for looming-evoked freezing, two environmental factors that modulate its expression, and using a genetically tractable system affording the use of large sample sizes, places us in an unique position to understand how a information about a threat is integrated with cues from the environment to guide the choice of whether to freeze (our goal). To assess how social information impinges on the circuit for freezing, we will examine the sensory inputs and neuromodulators that mediate this process, mapping their connections to DNp09 neurons (Aim 1). We ask whether learning is required for the spatial modulation of freezing, which cues flies are using to discriminate different places and which brain circuits mediate this process (Aim 2). Finally, we will study how activity of DNp09 neurons drives freezing (Aim 3). This project will provide a comprehensive understanding of the mechanism of freezing and its modulation by the environment, from single neurons to behaviour.
Max ERC Funding
1 969 750 €
Duration
Start date: 2019-02-01, End date: 2024-01-31
Project acronym Acclimatize
Project Hypothalamic mechanisms of thermal homeostasis and adaptation
Researcher (PI) Jan SIEMENS
Host Institution (HI) UNIVERSITATSKLINIKUM HEIDELBERG
Country Germany
Call Details Consolidator Grant (CoG), LS5, ERC-2017-COG
Summary Mammalian organisms possess the remarkable ability to maintain internal body temperature (Tcore) within a narrow range close to 37°C despite wide environmental temperature variations. The brain’s neural “thermostat” is made up by central circuits in the hypothalamic preoptic area (POA), which orchestrate peripheral thermoregulatory responses to maintain Tcore. Thermogenesis requires metabolic fuel, suggesting intricate connections between the thermoregulatory centre and hypothalamic circuits controlling energy balance. How the POA detects and integrates temperature and metabolic information to achieve thermal balance is largely unknown. A major question is whether this circuitry could be harnessed therapeutically to treat obesity.
We have recently identified the first known molecular temperature sensor in thermoregulatory neurons of the POA, transient receptor potential melastatin 2 (TRPM2), a thermo-sensitive ion channel. I aim to use TRPM2 as a molecular marker to gain access to and probe the function of thermoregulatory neurons in vivo. I propose a multidisciplinary approach, combining local, in vivo POA temperature stimulation with optogenetic circuit-mapping to uncover the molecular and cellular logic of the hypothalamic thermoregulatory centre and to assess its medical potential to counteract metabolic syndrome.
Acclimation is a beneficial adaptive process that fortifies thermal responses upon environmental temperature challenges. Thermoregulatory neuron plasticity is thought to mediate acclimation. Conversely, maladaptive thermoregulatory changes affect obesity. The cell-type-specific neuronal plasticity mechanisms underlying these changes within the POA, however, are unknown.
Using ex-vivo slice electrophysiology and in vivo imaging, I propose to characterize acclimation- and obesity-induced plasticity of thermoregulatory neurons. Ultimately, I aim to manipulate thermoregulatory neuron plasticity to test its potential counter-balancing effect on obesity.
Summary
Mammalian organisms possess the remarkable ability to maintain internal body temperature (Tcore) within a narrow range close to 37°C despite wide environmental temperature variations. The brain’s neural “thermostat” is made up by central circuits in the hypothalamic preoptic area (POA), which orchestrate peripheral thermoregulatory responses to maintain Tcore. Thermogenesis requires metabolic fuel, suggesting intricate connections between the thermoregulatory centre and hypothalamic circuits controlling energy balance. How the POA detects and integrates temperature and metabolic information to achieve thermal balance is largely unknown. A major question is whether this circuitry could be harnessed therapeutically to treat obesity.
We have recently identified the first known molecular temperature sensor in thermoregulatory neurons of the POA, transient receptor potential melastatin 2 (TRPM2), a thermo-sensitive ion channel. I aim to use TRPM2 as a molecular marker to gain access to and probe the function of thermoregulatory neurons in vivo. I propose a multidisciplinary approach, combining local, in vivo POA temperature stimulation with optogenetic circuit-mapping to uncover the molecular and cellular logic of the hypothalamic thermoregulatory centre and to assess its medical potential to counteract metabolic syndrome.
Acclimation is a beneficial adaptive process that fortifies thermal responses upon environmental temperature challenges. Thermoregulatory neuron plasticity is thought to mediate acclimation. Conversely, maladaptive thermoregulatory changes affect obesity. The cell-type-specific neuronal plasticity mechanisms underlying these changes within the POA, however, are unknown.
Using ex-vivo slice electrophysiology and in vivo imaging, I propose to characterize acclimation- and obesity-induced plasticity of thermoregulatory neurons. Ultimately, I aim to manipulate thermoregulatory neuron plasticity to test its potential counter-balancing effect on obesity.
Max ERC Funding
1 902 500 €
Duration
Start date: 2018-09-01, End date: 2023-08-31
Project acronym ACoolTouch
Project Neural mechanisms of multisensory perceptual binding
Researcher (PI) James Francis Alexander Poulet
Host Institution (HI) MAX DELBRUECK CENTRUM FUER MOLEKULARE MEDIZIN IN DER HELMHOLTZ-GEMEINSCHAFT (MDC)
Country Germany
Call Details Consolidator Grant (CoG), LS5, ERC-2015-CoG
Summary Sensory perception involves the discrimination and binding of multiple modalities of sensory input. This is especially evident in the somatosensory system where different modalities of sensory input, including thermal and mechanosensory, are combined to generate a unified percept. The neural mechanisms of multisensory binding are unknown, in part because sensory perception is typically studied within a single modality in a single brain region. I propose a multi-level approach to investigate thermo-tactile processing in the mouse forepaw system from the primary sensory afferent neurons to thalamo-cortical circuits and behaviour.
The mouse forepaw system is the ideal system to investigate multisensory binding as the sensory afferent neurons are well investigated, cell type-specific lines are available, in vivo optogenetic manipulation is possible both in sensory afferent neurons and central circuits and we have developed high-resolution somatosensory perception behaviours. We have previously shown that mouse primary somatosensory forepaw cortical neurons respond to both tactile and thermal stimuli and are required for non-noxious cooling perception. With multimodal neurons how, then, is it possible to both discriminate and bind thermal and tactile stimuli?
I propose 3 objectives to address this question. We will first, perform functional mapping of the thermal and tactile pathways to cortex; second, investigate the neural mechanisms of thermo-tactile discrimination in behaving mice; and third, compare neural processing during two thermo-tactile binding tasks, the first using passively applied stimuli, and the second, active manipulation of thermal objects.
At each stage we will perform cell type-specific neural recordings and causal optogenetic manipulations in awake and behaving mice. Our multi-level approach will provide a comprehensive investigation into how the brain performs multisensory perceptual binding: a fundamental yet unsolved problem in neuroscience.
Summary
Sensory perception involves the discrimination and binding of multiple modalities of sensory input. This is especially evident in the somatosensory system where different modalities of sensory input, including thermal and mechanosensory, are combined to generate a unified percept. The neural mechanisms of multisensory binding are unknown, in part because sensory perception is typically studied within a single modality in a single brain region. I propose a multi-level approach to investigate thermo-tactile processing in the mouse forepaw system from the primary sensory afferent neurons to thalamo-cortical circuits and behaviour.
The mouse forepaw system is the ideal system to investigate multisensory binding as the sensory afferent neurons are well investigated, cell type-specific lines are available, in vivo optogenetic manipulation is possible both in sensory afferent neurons and central circuits and we have developed high-resolution somatosensory perception behaviours. We have previously shown that mouse primary somatosensory forepaw cortical neurons respond to both tactile and thermal stimuli and are required for non-noxious cooling perception. With multimodal neurons how, then, is it possible to both discriminate and bind thermal and tactile stimuli?
I propose 3 objectives to address this question. We will first, perform functional mapping of the thermal and tactile pathways to cortex; second, investigate the neural mechanisms of thermo-tactile discrimination in behaving mice; and third, compare neural processing during two thermo-tactile binding tasks, the first using passively applied stimuli, and the second, active manipulation of thermal objects.
At each stage we will perform cell type-specific neural recordings and causal optogenetic manipulations in awake and behaving mice. Our multi-level approach will provide a comprehensive investigation into how the brain performs multisensory perceptual binding: a fundamental yet unsolved problem in neuroscience.
Max ERC Funding
1 999 877 €
Duration
Start date: 2016-09-01, End date: 2021-08-31
Project acronym ALS-Networks
Project Defining functional networks of genetic causes for ALS and related neurodegenerative disorders
Researcher (PI) Edor Kabashi
Host Institution (HI) INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE
Country France
Call Details Consolidator Grant (CoG), LS5, ERC-2015-CoG
Summary Brain and spinal cord diseases affect 38% of the European population and cost over 800 billion € annually; representing by far the largest health challenge. ALS is a prevalent neurological disease caused by motor neuron death with an invariably fatal outcome. I contributed to ALS research with the groundbreaking discovery of TDP-43 mutations, functionally characterized these mutations in the first vertebrate model and demonstrated a genetic interaction with another major ALS gene FUS. Emerging evidence indicates that four major causative factors in ALS, C9orf72, TDP-43, FUS & SQSTM1, genetically interact and could function in common cellular mechanisms. Here, I will develop zebrafish transgenic lines for all four genes, using state of the art genomic editing tools to combine simultaneous gene knockout and expression of the mutant alleles. Using these innovative disease models I will study the functional interactions amongst these four genes and their converging effect on key ALS pathogenic mechanisms: autophagy degradation, stress granule formation and RNA regulation. These studies will permit to pinpoint the molecular cascades that underlie ALS-related neurodegeneration. We will further expand the current ALS network by proposing and validating novel genetic interactors, which will be further screened for disease-causing variants and as pathological markers in patient samples. The power of zebrafish as a vertebrate model amenable to high-content phenotype-based screens will enable discovery of bioactive compounds that are neuroprotective in multiple animal models of disease. This project will increase the fundamental understanding of the relevance of C9orf72, TDP-43, FUS and SQSTM1 by developing animal models to characterize common pathophysiological mechanisms. Furthermore, I will uncover novel genetic, disease-related and pharmacological modifiers to extend the ALS network that will facilitate development of therapeutic strategies for neurodegenerative disorders
Summary
Brain and spinal cord diseases affect 38% of the European population and cost over 800 billion € annually; representing by far the largest health challenge. ALS is a prevalent neurological disease caused by motor neuron death with an invariably fatal outcome. I contributed to ALS research with the groundbreaking discovery of TDP-43 mutations, functionally characterized these mutations in the first vertebrate model and demonstrated a genetic interaction with another major ALS gene FUS. Emerging evidence indicates that four major causative factors in ALS, C9orf72, TDP-43, FUS & SQSTM1, genetically interact and could function in common cellular mechanisms. Here, I will develop zebrafish transgenic lines for all four genes, using state of the art genomic editing tools to combine simultaneous gene knockout and expression of the mutant alleles. Using these innovative disease models I will study the functional interactions amongst these four genes and their converging effect on key ALS pathogenic mechanisms: autophagy degradation, stress granule formation and RNA regulation. These studies will permit to pinpoint the molecular cascades that underlie ALS-related neurodegeneration. We will further expand the current ALS network by proposing and validating novel genetic interactors, which will be further screened for disease-causing variants and as pathological markers in patient samples. The power of zebrafish as a vertebrate model amenable to high-content phenotype-based screens will enable discovery of bioactive compounds that are neuroprotective in multiple animal models of disease. This project will increase the fundamental understanding of the relevance of C9orf72, TDP-43, FUS and SQSTM1 by developing animal models to characterize common pathophysiological mechanisms. Furthermore, I will uncover novel genetic, disease-related and pharmacological modifiers to extend the ALS network that will facilitate development of therapeutic strategies for neurodegenerative disorders
Max ERC Funding
2 000 000 €
Duration
Start date: 2017-04-01, End date: 2022-03-31
Project acronym ALZSYN
Project Imaging synaptic contributors to dementia
Researcher (PI) Tara Spires-Jones
Host Institution (HI) THE UNIVERSITY OF EDINBURGH
Country United Kingdom
Call Details Consolidator Grant (CoG), LS5, ERC-2015-CoG
Summary Alzheimer's disease, the most common cause of dementia in older people, is a devastating condition that is becoming a public health crisis as our population ages. Despite great progress recently in Alzheimer’s disease research, we have no disease modifying drugs and a decade with a 99.6% failure rate of clinical trials attempting to treat the disease. This project aims to develop relevant therapeutic targets to restore brain function in Alzheimer’s disease by integrating human and model studies of synapses. It is widely accepted in the field that alterations in amyloid beta initiate the disease process. However the cascade leading from changes in amyloid to widespread tau pathology and neurodegeneration remain unclear. Synapse loss is the strongest pathological correlate of dementia in Alzheimer’s, and mounting evidence suggests that synapse degeneration plays a key role in causing cognitive decline. Here I propose to test the hypothesis that the amyloid cascade begins at the synapse leading to tau pathology, synapse dysfunction and loss, and ultimately neural circuit collapse causing cognitive impairment. The team will use cutting-edge multiphoton and array tomography imaging techniques to test mechanisms downstream of amyloid beta at synapses, and determine whether intervening in the cascade allows recovery of synapse structure and function. Importantly, I will combine studies in robust models of familial Alzheimer’s disease with studies in postmortem human brain to confirm relevance of our mechanistic studies to human disease. Finally, human stem cell derived neurons will be used to test mechanisms and potential therapeutics in neurons expressing the human proteome. Together, these experiments are ground-breaking since they have the potential to further our understanding of how synapses are lost in Alzheimer’s disease and to identify targets for effective therapeutic intervention, which is a critical unmet need in today’s health care system.
Summary
Alzheimer's disease, the most common cause of dementia in older people, is a devastating condition that is becoming a public health crisis as our population ages. Despite great progress recently in Alzheimer’s disease research, we have no disease modifying drugs and a decade with a 99.6% failure rate of clinical trials attempting to treat the disease. This project aims to develop relevant therapeutic targets to restore brain function in Alzheimer’s disease by integrating human and model studies of synapses. It is widely accepted in the field that alterations in amyloid beta initiate the disease process. However the cascade leading from changes in amyloid to widespread tau pathology and neurodegeneration remain unclear. Synapse loss is the strongest pathological correlate of dementia in Alzheimer’s, and mounting evidence suggests that synapse degeneration plays a key role in causing cognitive decline. Here I propose to test the hypothesis that the amyloid cascade begins at the synapse leading to tau pathology, synapse dysfunction and loss, and ultimately neural circuit collapse causing cognitive impairment. The team will use cutting-edge multiphoton and array tomography imaging techniques to test mechanisms downstream of amyloid beta at synapses, and determine whether intervening in the cascade allows recovery of synapse structure and function. Importantly, I will combine studies in robust models of familial Alzheimer’s disease with studies in postmortem human brain to confirm relevance of our mechanistic studies to human disease. Finally, human stem cell derived neurons will be used to test mechanisms and potential therapeutics in neurons expressing the human proteome. Together, these experiments are ground-breaking since they have the potential to further our understanding of how synapses are lost in Alzheimer’s disease and to identify targets for effective therapeutic intervention, which is a critical unmet need in today’s health care system.
Max ERC Funding
2 000 000 €
Duration
Start date: 2016-11-01, End date: 2021-10-31
Project acronym ANewSpike
Project A new type of spike: Homoclinic spike generation in cells and networks
Researcher (PI) Susanne Schreiber
Host Institution (HI) HUMBOLDT-UNIVERSITAET ZU BERLIN
Country Germany
Call Details Consolidator Grant (CoG), LS5, ERC-2019-COG
Summary Action potentials are not all equal. Despite shared biophysical principles and even similar action-potential shape, neurons with different spike generators can encode vastly different aspects of a stimulus and result in radically different behaviors of the embedding network. Differences between spike generators may be hard to discern because the information content of a spike train is not obvious to the naked eye. This is where computational analysis comes into play: theoretical research has shown that spike generation can be classified into a few dynamical types with qualitatively distinct computational properties. Among these, so-called homoclinic spikes – unlike the other commonly considered types – have been largely ignored. Yet, homoclinic spike generators are special because only they react with high sensitivity to inputs during the refractory period. Indeed, it is directly after a spike when homoclinic spikers “listen” best.
As we recently demonstrated, this unique property has computationally exciting consequences: it can provoke a dramatic increase in network synchronization in response to minimal changes in physiological parameters, without requiring alterations in synaptic strength or connectivity. Supported by in-vitro evidence for homoclinic spiking in the rodent brain, ANewSpike explores the intriguing hypothesis that this “forgotten“ spike generator provides a unifying framework for the induction of epileptic activity by a wide range of physiological trigger parameters, from temperature to energy deprivation. Using a theory-experiment approach, we explore (i) the prevalence of homoclinic spiking in the brain, (ii) its ability to promote the transmission of high frequencies, and (iii) its ability to boost network synchronization. Our multi-scale study aims to add a novel dimension to our understanding of neural dynamics at the cellular and network level by revealing homoclinic spiking as an integral part of brain dynamics in both health and pathology.
Summary
Action potentials are not all equal. Despite shared biophysical principles and even similar action-potential shape, neurons with different spike generators can encode vastly different aspects of a stimulus and result in radically different behaviors of the embedding network. Differences between spike generators may be hard to discern because the information content of a spike train is not obvious to the naked eye. This is where computational analysis comes into play: theoretical research has shown that spike generation can be classified into a few dynamical types with qualitatively distinct computational properties. Among these, so-called homoclinic spikes – unlike the other commonly considered types – have been largely ignored. Yet, homoclinic spike generators are special because only they react with high sensitivity to inputs during the refractory period. Indeed, it is directly after a spike when homoclinic spikers “listen” best.
As we recently demonstrated, this unique property has computationally exciting consequences: it can provoke a dramatic increase in network synchronization in response to minimal changes in physiological parameters, without requiring alterations in synaptic strength or connectivity. Supported by in-vitro evidence for homoclinic spiking in the rodent brain, ANewSpike explores the intriguing hypothesis that this “forgotten“ spike generator provides a unifying framework for the induction of epileptic activity by a wide range of physiological trigger parameters, from temperature to energy deprivation. Using a theory-experiment approach, we explore (i) the prevalence of homoclinic spiking in the brain, (ii) its ability to promote the transmission of high frequencies, and (iii) its ability to boost network synchronization. Our multi-scale study aims to add a novel dimension to our understanding of neural dynamics at the cellular and network level by revealing homoclinic spiking as an integral part of brain dynamics in both health and pathology.
Max ERC Funding
2 000 000 €
Duration
Start date: 2021-01-01, End date: 2025-12-31
Project acronym ARTTOUCH
Project Generating artificial touch: from the contribution of single tactile afferents to the encoding of complex percepts, and their implications for clinical innovation
Researcher (PI) Rochelle ACKERLEY
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Country France
Call Details Consolidator Grant (CoG), LS5, ERC-2017-COG
Summary Somatosensation encompass a wide range of processes, from feeling touch to temperature, as well as experiencing pleasure and pain. When afferent inputs are degraded or removed, such as in neuropathies or amputation, exploring the world becomes extremely difficult. Chronic pain is a major health issue that greatly diminishes quality of life and is one of the most disabling and costly conditions in Europe. The loss of a body part is common due to accidents, tumours, or peripheral diseases, and it has instantaneous effects on somatosensory functioning. Treating such disorders entails detailed knowledge about how somatosensory signals are encoded. Understanding these processes will enable the restoration of healthy function, such as providing real-time, naturalistic feedback in prostheses. To date, no prosthesis currently provides long-term sensory feedback, yet accomplishing this will lead to great quality of life improvements. The present proposal aims to uncover how basic tactile processes are encoded and represented centrally, as well as how more complex somatosensation is generated (e.g. wetness, pleasantness). Novel investigations will be conducted in humans to probe these mechanisms, including peripheral in vivo recording (microneurography) and neural stimulation, combined with advanced brain imaging and behavioural experiments. Preliminary work has shown the feasibility of the approach, where it is possible to visualise the activation of single mechanoreceptive afferents in the human brain. The multi-disciplinary approach unites detailed, high-resolution, functional investigations with actual sensations generated. The results will elucidate how basic and complex somatosensory processes are encoded, providing insights into the recovery of such signals. The knowledge gained aims to provide pain-free, efficient diagnostic capabilities for detecting and quantifying a range of somatosensory disorders, as well as identifying new potential therapeutic targets.
Summary
Somatosensation encompass a wide range of processes, from feeling touch to temperature, as well as experiencing pleasure and pain. When afferent inputs are degraded or removed, such as in neuropathies or amputation, exploring the world becomes extremely difficult. Chronic pain is a major health issue that greatly diminishes quality of life and is one of the most disabling and costly conditions in Europe. The loss of a body part is common due to accidents, tumours, or peripheral diseases, and it has instantaneous effects on somatosensory functioning. Treating such disorders entails detailed knowledge about how somatosensory signals are encoded. Understanding these processes will enable the restoration of healthy function, such as providing real-time, naturalistic feedback in prostheses. To date, no prosthesis currently provides long-term sensory feedback, yet accomplishing this will lead to great quality of life improvements. The present proposal aims to uncover how basic tactile processes are encoded and represented centrally, as well as how more complex somatosensation is generated (e.g. wetness, pleasantness). Novel investigations will be conducted in humans to probe these mechanisms, including peripheral in vivo recording (microneurography) and neural stimulation, combined with advanced brain imaging and behavioural experiments. Preliminary work has shown the feasibility of the approach, where it is possible to visualise the activation of single mechanoreceptive afferents in the human brain. The multi-disciplinary approach unites detailed, high-resolution, functional investigations with actual sensations generated. The results will elucidate how basic and complex somatosensory processes are encoded, providing insights into the recovery of such signals. The knowledge gained aims to provide pain-free, efficient diagnostic capabilities for detecting and quantifying a range of somatosensory disorders, as well as identifying new potential therapeutic targets.
Max ERC Funding
1 223 639 €
Duration
Start date: 2019-01-01, End date: 2023-12-31
Project acronym AstroWireSyn
Project Wiring synaptic circuits with astroglial connexins: mechanisms, dynamics and impact for critical period plasticity
Researcher (PI) Nathalie Rouach
Host Institution (HI) COLLEGE DE FRANCE
Country France
Call Details Consolidator Grant (CoG), LS5, ERC-2015-CoG
Summary Brain information processing is commonly thought to be a neuronal performance. However recent data point to a key role of astrocytes in brain development, activity and pathology. Indeed astrocytes are now viewed as crucial elements of the brain circuitry that control synapse formation, maturation, activity and elimination. How do astrocytes exert such control is matter of intense research, as they are now known to participate in critical developmental periods as well as in psychiatric disorders involving synapse alterations. Thus unraveling how astrocytes control synaptic circuit formation and maturation is crucial, not only for our understanding of brain development, but also for identifying novel therapeutic targets.
We recently found that connexin 30 (Cx30), an astroglial gap junction subunit expressed postnatally, tunes synaptic activity via an unprecedented non-channel function setting the proximity of glial processes to synaptic clefts, essential for synaptic glutamate clearance efficacy. Our work not only reveals Cx30 as a key determinant of glial synapse coverage, but also extends the classical model of neuroglial interactions in which astrocytes are generally considered as extrasynaptic elements indirectly regulating neurotransmission. Yet the molecular mechanisms involved in such control, its dynamic regulation by activity and impact in a native developmental context are unknown. We will now address these important questions, focusing on the involvement of this novel astroglial function in wiring developing synaptic circuits.
Thus using a multidisciplinary approach we will investigate:
1) the molecular and cellular mechanisms underlying Cx30 regulation of synaptic function
2) the activity-dependent dynamics of Cx30 function at synapses
3) a role for Cx30 in wiring synaptic circuits during critical developmental periods
This ambitious project will provide essential knowledge on the molecular mechanisms underlying astroglial control of synaptic circuits.
Summary
Brain information processing is commonly thought to be a neuronal performance. However recent data point to a key role of astrocytes in brain development, activity and pathology. Indeed astrocytes are now viewed as crucial elements of the brain circuitry that control synapse formation, maturation, activity and elimination. How do astrocytes exert such control is matter of intense research, as they are now known to participate in critical developmental periods as well as in psychiatric disorders involving synapse alterations. Thus unraveling how astrocytes control synaptic circuit formation and maturation is crucial, not only for our understanding of brain development, but also for identifying novel therapeutic targets.
We recently found that connexin 30 (Cx30), an astroglial gap junction subunit expressed postnatally, tunes synaptic activity via an unprecedented non-channel function setting the proximity of glial processes to synaptic clefts, essential for synaptic glutamate clearance efficacy. Our work not only reveals Cx30 as a key determinant of glial synapse coverage, but also extends the classical model of neuroglial interactions in which astrocytes are generally considered as extrasynaptic elements indirectly regulating neurotransmission. Yet the molecular mechanisms involved in such control, its dynamic regulation by activity and impact in a native developmental context are unknown. We will now address these important questions, focusing on the involvement of this novel astroglial function in wiring developing synaptic circuits.
Thus using a multidisciplinary approach we will investigate:
1) the molecular and cellular mechanisms underlying Cx30 regulation of synaptic function
2) the activity-dependent dynamics of Cx30 function at synapses
3) a role for Cx30 in wiring synaptic circuits during critical developmental periods
This ambitious project will provide essential knowledge on the molecular mechanisms underlying astroglial control of synaptic circuits.
Max ERC Funding
2 000 000 €
Duration
Start date: 2016-10-01, End date: 2022-03-31
Project acronym AXONGROWTH
Project Systematic analysis of the molecular mechanisms underlying axon growth during development and following injury
Researcher (PI) Oren Schuldiner
Host Institution (HI) WEIZMANN INSTITUTE OF SCIENCE
Country Israel
Call Details Consolidator Grant (CoG), LS5, ERC-2013-CoG
Summary Axon growth potential declines during development, contributing to the lack of effective regeneration in the adult central nervous system. What determines the intrinsic growth potential of neurites, and how such growth is regulated during development, disease and following injury is a fundamental question in neuroscience. Although multiple lines of evidence indicate that intrinsic growth capability is genetically encoded, its nature remains poorly defined. Neuronal remodeling of the Drosophila mushroom body offers a unique opportunity to study the mechanisms of various types of axon degeneration and growth. We have recently demonstrated that regrowth of axons following developmental pruning is not only distinct from initial outgrowth but also shares molecular similarities with regeneration following injury. In this proposal we combine state of the art tools from genomics, functional genetics and microscopy to perform a comprehensive study of the mechanisms underlying axon growth during development and following injury. First, we will combine genetic, biochemical and genomic studies to gain a mechanistic understanding of the developmental regrowth program. Next, we will perform extensive transcriptomic analyses and comparisons aimed at defining the genetic programs involved in initial axon growth, developmental regrowth, and regeneration following injury. Finally, we will harness the genetic power of Drosophila to perform a comprehensive functional analysis of genes and pathways, those previously known and new ones that we will discover, in various neurite growth paradigms. Importantly, these functional assays will be performed in the same organism, allowing us to use identical genetic mutations across our analyses. To this end, our identification of a new genetic program regulating developmental axon regrowth, together with emerging tools in genomics, places us in a unique position to gain a broad understanding of axon growth during development and following injury.
Summary
Axon growth potential declines during development, contributing to the lack of effective regeneration in the adult central nervous system. What determines the intrinsic growth potential of neurites, and how such growth is regulated during development, disease and following injury is a fundamental question in neuroscience. Although multiple lines of evidence indicate that intrinsic growth capability is genetically encoded, its nature remains poorly defined. Neuronal remodeling of the Drosophila mushroom body offers a unique opportunity to study the mechanisms of various types of axon degeneration and growth. We have recently demonstrated that regrowth of axons following developmental pruning is not only distinct from initial outgrowth but also shares molecular similarities with regeneration following injury. In this proposal we combine state of the art tools from genomics, functional genetics and microscopy to perform a comprehensive study of the mechanisms underlying axon growth during development and following injury. First, we will combine genetic, biochemical and genomic studies to gain a mechanistic understanding of the developmental regrowth program. Next, we will perform extensive transcriptomic analyses and comparisons aimed at defining the genetic programs involved in initial axon growth, developmental regrowth, and regeneration following injury. Finally, we will harness the genetic power of Drosophila to perform a comprehensive functional analysis of genes and pathways, those previously known and new ones that we will discover, in various neurite growth paradigms. Importantly, these functional assays will be performed in the same organism, allowing us to use identical genetic mutations across our analyses. To this end, our identification of a new genetic program regulating developmental axon regrowth, together with emerging tools in genomics, places us in a unique position to gain a broad understanding of axon growth during development and following injury.
Max ERC Funding
2 000 000 €
Duration
Start date: 2014-03-01, End date: 2019-02-28
Project acronym Brain circRNAs
Project Rounding the circle: Unravelling the biogenesis, function and mechanism of action of circRNAs in the Drosophila brain.
Researcher (PI) Sebastian Kadener
Host Institution (HI) THE HEBREW UNIVERSITY OF JERUSALEM
Country Israel
Call Details Consolidator Grant (CoG), LS5, ERC-2014-CoG
Summary Tight regulation of RNA metabolism is essential for normal brain function. This includes co and post-transcriptional regulation, which are extremely prevalent in neurons. Recently, circular RNAs (circRNAs), a highly abundant new type of regulatory non-coding RNA have been found across the animal kingdom. Two of these RNAs have been shown to act as miRNA sponges but no function is known for the thousands of other circRNAs, indicating the existence of a widespread layer of previously unknown gene regulation.
The present proposal aims to comprehensively determine the role and mode of actions of circRNAs in gene expression and RNA metabolism in the fly brain. We will do so by studying their biogenesis, transport, and mechanism of action, as well as by determining the roles of circRNAs in neuronal function and behaviour. Briefly, we will: 1) identify factors involved in the biogenesis, localization, and stabilization of circRNAs; 2) determine neuro-developmental, molecular, neural and behavioural phenotypes associated with down or up regulation of specific circRNAs; 3) study the molecular mechanisms of action of circRNAs: identify circRNAs that work as miRNA sponges and determine whether circRNAs can encode proteins or act as signalling molecules and 4) perform mechanistic studies in order to determine cause-effect relationships between circRNA function and brain physiology and behaviour.
The present proposal will reveal the key pathways by which circRNAs control gene expression and influence neuronal function and behaviour. Therefore it will be one of the pioneer works in the study of this new and important area of research, which we predict will fundamentally transform the study of gene expression regulation in the brain
Summary
Tight regulation of RNA metabolism is essential for normal brain function. This includes co and post-transcriptional regulation, which are extremely prevalent in neurons. Recently, circular RNAs (circRNAs), a highly abundant new type of regulatory non-coding RNA have been found across the animal kingdom. Two of these RNAs have been shown to act as miRNA sponges but no function is known for the thousands of other circRNAs, indicating the existence of a widespread layer of previously unknown gene regulation.
The present proposal aims to comprehensively determine the role and mode of actions of circRNAs in gene expression and RNA metabolism in the fly brain. We will do so by studying their biogenesis, transport, and mechanism of action, as well as by determining the roles of circRNAs in neuronal function and behaviour. Briefly, we will: 1) identify factors involved in the biogenesis, localization, and stabilization of circRNAs; 2) determine neuro-developmental, molecular, neural and behavioural phenotypes associated with down or up regulation of specific circRNAs; 3) study the molecular mechanisms of action of circRNAs: identify circRNAs that work as miRNA sponges and determine whether circRNAs can encode proteins or act as signalling molecules and 4) perform mechanistic studies in order to determine cause-effect relationships between circRNA function and brain physiology and behaviour.
The present proposal will reveal the key pathways by which circRNAs control gene expression and influence neuronal function and behaviour. Therefore it will be one of the pioneer works in the study of this new and important area of research, which we predict will fundamentally transform the study of gene expression regulation in the brain
Max ERC Funding
1 971 750 €
Duration
Start date: 2016-02-01, End date: 2021-01-31
