Andres V. Maricq - US grants

This grant application is a request for an ADAMHA Scientist development award (SDA). We propose a program for a clinically trained research scientist whose career goals require training in molecular biology. This program will consist of a firm grounding in molecular biological research techniques as well as participation in courses and functions of the UCSF Program in Biological Sciences. It will encompass relevant courses given at the Cold Spring Harbor Laboratories, and selected short-courses at meetings such as the Annual Meeting of the Society for Neuroscience. The major objective of the proposed project is to understand how biogenic amines such as serotonin (5HT) modulate cellular function. 5HT exerts its physiological effects by binding to a family of pharmacologically distinct cell surface receptor subtypes. I will focus on a particular serotonin receptor subtype, namely the 5HT3 receptor (5HT3R). This proposal addresses the specific question of how the molecular structure of the 5HT3 receptor relates to its physiological role in the nervous system. Isolation of the gene(s) encoding the 5HT3R will permit structure-function analysis and will provide the necessary molecular probes to investigate the cellular and subcellular localization of the receptor. Serotonin (5HT) acts as a neurotransmitter, but also has hormonal and mitogenic actions in non-neuronal tissues. Until recently the variety of cell surface receptors that respond to 5HT were all believed to act by modulating intracellular second messenger systems. Recently, however, 5HT3R subtypes were shown to act as ligand-gated ion channels that promote rapid depolarizing responses in neurons. Although little is known about the specific function of these receptors, selective 5HT3R antagonists have clinical value as antiemetic agents and are thus used to prevent the drug- induced emesis associated with chemotherapeutic drug regimens. The specific aims of this proposal are to pursue three independent yet overlapping strategies for the elucidation of the primary structure of the 5HT3R. Using a variety of cell lines and tissues that express 5HT3R, we will develop PCR, protein purification and functional expression strategies to isolate a cDNA clone encoding a member of the 5HT3R family. The long- term goal of the proposed experiments is to examine the physiological properties of this receptor in heterologous cell systems and to characterize sites of 5HT3R expression within the central and peripheral nervous systems.

DESCRIPTION: The nervous system relays and processes information by releasing neurotransmitters at the points of specialized synaptic contact between neurons. In the mammalian nervous system, glutamate serves as the major excitatory neurotransmitter and is implicated in processes as diverse as learning and memory, epilepsy, and cell death associated with stroke and degenerative neurological disorders. The understanding of synaptic signaling by glutamate has been limited by the lack of knowledge of the molecular machinery required for the development and function of the glutamanergic synapse. The aim of this proposal is to pursue a combined genetic and electrophysiological study of glutamate receptor function in the simple nervous system of the soil nematode Caenorhabditis elegans. Putative glutamate receptors have been identified in C. elegans and a deletion mutation in one receptor, glr-1, interferes only with the worms' withdrawal response to mechanical stimulation. This response is primarily mediated by a single bifunctional neuron, ASH, that mediated withdrawal to both mechanical and osmotic stimuli. To learn more about glutamate receptor function in C. elegans, it is proposed to clone additional genes encoding glutamate receptors and to define the expression of these gene products in the C. elegans nervous system. To examine the behavioral role of glutamine receptors, genetic techniques will be used to generate transgenic worms that lack one or several glutamate receptor subunits. In vertebrates, excessive glutamate or exposure to excitotoxic drugs that activate glutamate receptors can cause a receptor-dependent neuronal death. In C. elegans, these same excitotoxins can cause paralysis or death of the worm. Additional genes required for glutamanergic function will be identified by screening for genes that when mutated confer a recessive resistance to drug-induced paralysis. The electrophysiological and pharmacological properties of C. elegans glutamate receptors will be studied by functional expression in Xenopus oocytes. To characterize glutamate receptor function in vivo, whole-cell currents will be recorded from identified neurons in C. elegans. The proposed studies will help us learn how glutamate receptors contribute to neuronal function in C. elegans. These studies will also identify additional genes required for glutamanergic signaling and may contribute to our understanding of stroke, excitotoxicity, and neuronal death.

The research supported by this NSF Faculty Early Career Development (CAREER) award examines the molecular basis of neuronal diversity. The nervous system contains tremendous numbers of specialized neurons that communicate with one another at distinct points of contact called synapses. Synaptic function underlies learning and memory and dysfunction of the synapse underlies many neurological disorders. As a neuron develops, it must express the molecules needed for synaptic communication. Amongst these molecules are the neurotransmitter receptors that receive the signal transmitted at the synapse. One important class of neurotransmitter receptors are those that bind to the neurotransmitter glutamate. If these receptors are improperly expressed, the function of the nervous system is disrupted.

The experiments supported by this NSF award will identify genes required for the expression of the NMDA subtypes of glutamate receptors. An experimental strategy that utilizes the tools of molecular biology and genetics will be used to discover genes that regulate the expression of these receptors in the simple model organism Caenorhabditis elegans. The NMDA receptors are most recognized as being involved in simple forms of associative learning and also play important roles in many neurological disorders.

This proposal integrates research into the fundamental mechanisms of neuronal function with the early training of undergraduates in the practice and theory of scientific inquiry. The studies will provide a detailed molecular-based understanding of the gene products required for the expression, assembly and localization of NMDA receptors in C. elegans. The strategy takes advantage of the powerful genetic techniques that enable rapid identification of gene products in this model organism. Almost all gene products required for synaptic function are conserved between simple organisms and humans. Therefore, the results of this research can be applicable to the study of the human nervous system.

DESCRIPTION (from applicant's abstract): Glutamate is an important excitatory neurotransmitter in both invertebrates and vertebrates. Altered glutamatergic neurotransmission is believed to be a key participant in the pathophysiology of many disorders of the nervous system, including Alzheimer's Disease, Parkinson's disease, and stroke. A large number of ionotropic glutamate receptors have been identified, many of which can combine to form functional receptors. However, it remains unclear how this diversity of glutamate receptors influences neuronal excitability and the control of behavior. The goal of the proposed research is to determine how specific glutamate receptors contribute to the control of locomotion by a simple neural circuit. We will determine how the expression and spatial organization of these receptors is regulated, we will examine the effects of mutating specific receptor subunits, we will elucidate the mechanism of action of these receptors by electrophysiological analysis, and we will use genetic strategies to discover additional genes that control the membrane expression of receptors. We have established that the locomotory control circuit in C. elegans is particularly advantageous for the study of how glutamate receptors are regulated and how they contribute to information processing by the circuit. We have also established a detailed neural map of the 10 identified C. elegans glutamate receptors. Six of these receptors, including 4 non-NMDA receptors and 2 NMDA receptors, are expressed in many of the locomotory control interneurons. We propose a variety of experimental approaches to test the hypothesis that glutamate receptors play critical roles in the control of locomotion of C. elegans. By generating mutations in these receptors, we will determine how glutamate receptors, singly and in combination, contribute to the control of locomotion. Using electrophysiological methods, we will record glutamate-evoked currents from wildtype and mutant worms. To assess receptor function, we will express cloned glutamate receptor subunits in heterologous cells and measure glutamate-gated currents. To determine whether glutamate receptors may assemble together at synapses, we will assess the subcellular co-localization of receptor subtypes. To identify genes that regulate glutamate receptor localization or membrane density of receptors, we will screen for extragenic suppressors of the dominant movement disorder observed in transgenic worms that express a dominantly active form of glutamate receptor in the locomotory control neurons.

DESCRIPTION (provided by applicant): The goal of the proposed research is to provide a genetic-based pharmacology for the study of synaptic and neural function. The tremendous diversity of toxins from the venoms of predatory Conus snail species provide a natural combinatorial-based pharmacology that can be used to selectively bind to the members of the large and diverse group of neurotransmitter receptors that mediate synaptic communication. We propose to use C. elegans to rapidly purify new toxins that will be of interest to the broad community of neurobiologists. We have three major aims. The first aim is to identify and purify peptide toxins from the venoms of Conus snails that disrupt the behavior of the soil nematode C. elegans by perturbing nervous system function. A long-term goal of this strategy is to use Conus toxins as specific probes that will permit the identification of new gene products that contribute to nervous system function. The second aim is to identify and purify peptide toxins that block specific ligand-gated currents in muscles and neurons of C. elegans. These toxins will be invaluable for C. elegans neurobiologists and will allow for detailed mechanistic studies of synaptic transmission in C. elegans that currently are not possible because of the lack of specific pharmacological agents to acutely block specific classes of currents. We will use genetic and electrophysiological strategies to determine the site and mechanism of action of the purified Conus toxins. We have also used tissue-specific promoters to express active Conus toxins in transgenic worms. The Conus Im1 toxin blocks approximately 50% of the ACh-gated current at the neuromuscular junction. The gene products that contribute to this Im1-sensitive current have not yet been identified. Using a new genetic strategy, we will identify gene products that are required for this portion of the synaptic cholinergic current. The tremendous diversity inherent in Conus peptides, the specific and potent receptor interactions, and the fact that these peptides can be expressed in transgenic organisms in a tissue specific manner, may in the future provide a framework for designing genetic-based therapies for neurological disorders.

DESCRIPTION (provided by applicant): Glutamate is an important excitatory neurotransmitter in both invertebrates and vertebrates. Altered glutamatergic neurotransmission is believed to be a key factor in the pathophysiology of many disorders of the nervous system, including Alzheimers disease, Parkinson's disease, and stroke. A large number of ionotropic glutamate receptor subunits have been identified, many of which can combine to form functional receptors. However, it remains unclear how specific glutamate receptors are distributed to defined synapses and how their function contributes to neuronal information processing and the control of behavior. In C. elegans, we have demonstrated that AMPA (GLR-1, GLR-2), kainate (GLR-3, GLR-6) and NMDA (NMR-1) receptors contribute to specific avoidance and foraging behaviors. Using a genetic approach we have identified a CUB-domain transmembrane protein, SOL-1, that co-localizes with GLR-1 and is absolutely required for AMPA receptor function. We have also demonstrated that glutamate-gated currents can be recorded from Xenopus oocytes that express C. elegans AMPA receptors, but only if they are co-expressed with SOL-1 and STG-1, a distant homologue of vertebrate stargazin that we recently discovered. We now propose to extend these results and provide a mechanistic understanding of how different classes of iGluRs are distributed to and maintained at specific synapses, how they participate in synaptic communication, and how they contribute to the behavior of C. elegans. Using electrophysiological methods, we will record glutamate-evoked currents from wild-type and mutant worms. To assess receptor function, we will express cloned glutamate receptor subunits in heterologous cells and measure glutamate-gated currents. To determine which glutamate receptor subtypes localize together at synapses, we will assess the subcellular distribution of receptor subtypes. To identify genes that regulate glutamate receptor localization, function, or their membrane density, we will screen for additional suppressors of a hyper-reversal phenotype in transgenic C. elegans that express a gain-of-function lurcher variant of the GLR-1 AMPA receptor.

DESCRIPTION (provided by applicant): Our long-term goal is to elucidate the mechanisms that regulate growth factor signaling during development. Complex regulatory networks help create the correct signaling intensities underlying specific cell fate decisions, and provide the flexibility to allow cell fate decisions to be coordinated and modulated by environmental and physiological cues. Deregulation of growth factor signaling is linked to many/forms of human cancer. We study regulation of signaling by the epidermal growth factor receptor (EGFR), which is the prototypical evolutionary conserved growth factor receptor, and is the receptor implicated in the widest number of human cancers. Regulation of EGFR signaling can be broadly grouped into 3 layers. These include intramolecular inhibition in key components of the signaling pathway;regulation by trans-acting factors within cells responding to the EGFR;and regulation through cell-cell communication and cross-talk with other signaling pathways. We have developed novel methods for identifying mechanisms that regulate EGFR signaling during vulval development in the nematode C. elegans. Precise patterning of the vulva requires EGFR signaling to be subjected to all 3 layers of regulation. Small deviations from this regulation result in quantifiable changes in vulval patterning. In this proposal, we study 3 new regulatory mechanisms. We will use molecular, genetic, and biochemical approaches to: (1) determine how intramolecular inhibition of SOS, a key component of the EGFR pathway, helps regulate EGFR signaling intensity;(2) determine how the CLR-1 receptor protein tyrosine phosphatase inhibits EGFR signaling;and (3) determine how the new locus, ear-1, regulates EGFR signaling during vulval cell fate specification.

DESCRIPTION (provided by applicant): Nervous systems are plastic, that is, they can change with experience allowing us to learn, remember and forget. Experience-dependent plasticity occurs in part at synapses - specialized points of contact that mediate signaling between neurons. Experiences, sensations and emotions strengthen or weaken these connections shaping how the nervous system processes and stores information. Our long-term scientific goal is to uncover the molecular machinery that controls synaptic plasticity, as well as to understand how components of this machinery are assembled, and delivered to and regulated at synapses. The AMPA subtypes of ionotropic glutamate receptors (AMPARs) mediate synaptic transmission at most excitatory synapses. We have developed new genetic strategies to uncover the molecular machinery required for synaptic transmission at glutamatergic synapses in C. elegans. In a series of studies, we identified four classes of evolutionarily conserved auxiliary subunits that contribute to AMPAR function, showed that they have dramatic effects on in vivo glutamate-gated currents, and demonstrated that mutations in these genes predictably modify AMPAR-mediated behaviors. We also discovered that the delivery and removal of synaptic AMPARs was dependent on kinesin-1 microtubule-dependent motors. Thus, AMPAR transport along neuronal processes, and glutamate-gated currents, are dramatically reduced in unc-116 mutants (KIF5) and klc-2 mutants (Kinesin light chain 2). These findings led us to search for signaling molecules that regulate the transport of AMPARs. We have now identified two classes of evolutionarily conserved kinases that contribute to the transport of AMPARs to synapses. These same kinases are implicated in cellular models of learning and memory, such as long-term potentiation and long-term depression. We now plan to test the hypothesis that these kinase-signaling pathways contribute to the regulated delivery of synaptic AMPARs and their auxiliary proteins. We predict that what we learn from our proposed studies will have immediate relevance to ongoing studies of synaptic plasticity, learning and memory in vertebrates. Thus, our studies could contribute to new diagnostic or therapeutic modalities for disorders associated with altered neurotransmission in the brain.

DESCRIPTION Abstract: The ability to learn and remember is essential for all aspects of life. To better understand these processes in relation to health and disease, we propose a new approach to studying how neural circuits compute, store information and control behavior. We will develop new strategies and techniques for simultaneous measurements of learned behaviors, synaptic plasticity, and neuronal activity in a live animal. We predict that microcircuits in simple organisms will be more tractable to these studies and that the lessons learned will be of immediate relevance to complex nervous systems that contain more numerous and elaborate circuits. Therefore, we plan to focus our research program on identified microcircuits in the simple nervous system of the nematode C. elegans and address the following questions: a) What changes occur during synaptic plasticity and how are these changes controlled? b) How does synaptic plasticity lead to long-lived changes in neuronal and network activity? c) How do neural networks compute information and control behavior? To begin to address the above questions, we need new tools and techniques that will facilitate our goal to measure synaptic changes that occur during learning. Towards this end, we will develop microfluidics-based conditional learning paradigms; lanthanide-based luminescence techniques for enhanced detection of synaptic proteins; and new strategies for in vivo measurements of neuronal activity using voltage-sensitive dyes. The development of these new techniques will allow real-time measurements of the changes that occur during learning and offer a better understanding of the molecular mechanisms that contribute to learning and memory. To compliment this approach, we will also develop genetic strategies for the identification and rapid cloning of new genes required for these complex processes. Public Health Relevance: The ability to learn and remember is essential for a happy and productive life. Even mild loss of one's mem

DESCRIPTION (provided by applicant): We request funding from the Shared Instrumentation Grant Program (S10) to purchase a Covaris E210 Adaptive Focused Acoustic (AFA) instrument for the extraction of cellular RNA and the preparation of DNA for sequencing. The E210 would relieve the current bottleneck that is common to many of the ongoing genome projects at the University of Utah, namely that of preparing high quality DNA for complex sequencing efforts. The E210 will enable new strategies for identifying mutations that disrupt nervous system function and behavior, help provide single cell transcriptome data from identified cells and neurons, and greatly increase the throughput and success rate of genome sequencing. Recent technological advances in "next generation" sequencing have dramatically transformed our approach to genetics: mutations that may be difficult or impossible to map and clone using standard techniques can now be identified via whole genome sequencing. Using a recently acquired Illumina Genome Analyzer II (GA II) that is supported by the University of Utah, NIH-funded researchers are characterizing genomes de novo, identifying genomic mutations and polymorphisms, and cataloguing transcriptomes. DNA sequencing is critically dependent on quality DNA and RNA and conventional shearing methods lead to unacceptable loss of limited and precious material and does not prepare suitably homogenous DNA. Therefore, to increase the scope of our research efforts while simultaneously improving the efficiency and decreasing the costs of sequencing, we request funding to purchase the Covaris E210, which will allow us to adequately control the processes of tissue disruption, cell lysis, emulsification and production of sequencing-grade DNA. NIH funded researchers who are studying neurotransmission, protein trafficking, and receptor biology will use this instrument. Additionally, this instrument will be invaluable in ongoing efforts to identify novel pharmacological compounds from rare species of Cones snails that modify the functions of the brain and heart. These studies will impact a number of acute and chronic human diseases, including developmental and mental health disorders, excitotoxicity and stroke syndromes, degenerative diseases such as Parkinson's, Alzheimer's, and amyotrophic lateral sclerosis (ALS), and disorders of cardiac function.

DESCRIPTION (provided by applicant): Our long-term scientific goal is to gain a mechanistic understanding of synaptic transmission, with a focus on the establishment and regulation of acetylcholine receptors. Rapid cholinergic neurotransmission at muscles and in the brain is via synaptically released acetylcholine (ACh), which binds to and activates ion-channel forming pentameric receptors (AChRs). These receptors are evolutionarily conserved, and invertebrate and vertebrate organisms express large families of AChR subunits, which can form heteromeric or homomeric AChRs. The various receptors exhibit differential sensitivity to drugs (such as the addictive drug nicotine), and the diversity of receptors contributes to neuronal function and drug dependence. One receptor in particular, the homomeric a7 AChR, is associated with autism, anxiety and schizophrenia. The strength of a7-mediated neurotransmission is critically dependent on the localization and density of a7 AChRs; however, how these receptors or any AChRs are delivered to and localized at synapses is still not well understood. The goal of this proposal is to gain a mechanistic understanding of AChR-mediated synaptic signaling by using a genetic approach in Caenorhabditis elegans to identify signaling pathways that contribute to the delivery or function of a7-like AChRs. We previously demonstrated that synaptic currents mediated by ACR-16, a C. elegans a7 homologue, are dependent on CAM-1, a Ror class receptor tyrosine kinase (RTK). We now have preliminary data demonstrating that mutations in three genes encoding proteins that contribute to Wnt-mediated signaling (CWN-2/Wnt, LIN-17/Fzd, and DSH-1/Dvl) phenocopy the behavioral and electrophysiological defects found in cam-1 mutants. In this proposal we test the model that all four proteins contribute to a Wnt-mediated signaling pathway that is required for the delivery, localization or function of synaptic ACR-16 receptors, we elucidate downstream signaling components, and we measure the in vivo dynamics of receptor trafficking. Cholinergic neurotransmission is implicated in nicotine addiction, memory and cognition. Perturbations in a7 AChR regulation and function are thought to contribute to a broad spectrum of neuronal disorders such as autism, anxiety, and schizophrenia, as well as Alzheimer's and Parkinson's diseases. Because many of the gene products important for synaptic transmission are conserved from invertebrates to vertebrates, we predict that what we learn from our studies in C. elegans will have immediate relevance to ongoing studies in the vertebrate nervous system. Thus, our research efforts might ultimately lead to new diagnostic or therapeutic modalities for neuronal disorders associated with defects in cholinergic neurotransmission.

DESCRIPTION (provided by applicant): This proposal requests R13 support for a longstanding, well-attended, and well-received Gordon Research Conference (GRC) on Excitatory Synapses and Brain Function. The synapse is central to our understanding of circuit function and behavior. In the central nervous system, excitatory synapses represent the primary means of information processing by local circuits and communication between brain regions. Synapses serve as the site of action for many commonly prescribed medications and their disruption contributes to many neurological and psychiatric disorders. These include schizophrenia, autism, depression, substance abuse and addiction, Parkinson's disease, Alzheimer's disease, traumatic brain injury, stroke and epilepsy. In some cases, synaptic dysfunction is causal in disease, whereas in other cases it represents the downstream sequelae of one or more underlying molecular defects. In either case, a fundamental understanding of the formation, structure, molecular organization, signaling function, and plasticity of synapses is essential to progress in lessening the burden of human neurological disease and for predicting and improving mental health. This conference is unique in its focus on the excitatory synapse, and in its multidisciplinary group of participants including structural biologists, molecular and developmental biologists, cell biologists, biochemists, cell/molecular imagers, biophysicists and neurophysiologists. The conference is intended to relate fundamental insights in excitatory synaptic function to the impairments in synaptic function that occur in disease, as well as the maladaptive plasticity that occurs in substance abuse. The goal of the conference is to identify and highlight fundamental new insights into synaptic function and dysfunction from a thematic approach. The program has been designed to also highlight cutting edge approaches and to stimulate new concepts, methods and technologies within a sound biological framework of fundamental neuroscience. The conference will bring together expert scientists worldwide in an environment that is conducive to discussion and exchange of ideas. The exchange of ideas at this conference has been a driving force for the field. We expect the 2011 GRC on Excitatory Synapses and Brain Function will shape future scientific directions, and provide critical support for the mission of multiple institutes at NIH including NIMH, NINDS, NIDA and NIA. PUBLIC HEALTH RELEVANCE: The synapse is the fundamental unit of information processing in our brain. Synaptic dysfunction is responsible for many neurological and psychiatric diseases. This conference brings together experts on excitatory synapses and brain function to update progress and stimulate new approaches to improve mental health and reduce the burden of neurological disease.

? DESCRIPTION (provided by applicant): A major goal of neurobiology is to understand the control of behavior by neural circuits at the molecular level. This is also a major goal of clinica medicine as an increasing number of genetic polymorphisms associated with disorders such as autism, schizophrenia and depression suggest altered function of neural circuits. We propose molecular-based studies that will begin to elucidate the function of an experimentally accessible neural circuit in the genetically tractable model organism C. elegans. In preliminary experiments, we have demonstrated that this circuit has a general role in controlling navigation by C. elegans along gradients of sensory information. Many neurons in this circuit use the neurotransmitter glutamate, which activates multiple classes of postsynaptic ionotropic glutamate receptors (iGluRs) expressed in a single pair of interneurons. Interestingly, mutating these iGluRs has different effects on navigation during taxis behaviors. Furthermore, glutamate elicits complex action potentials and regional intracellular Ca2+ transients. The goals of our research are to provide mechanistic insights into how distinct sensory inputs to specific interneurons are transduced by different classes of postsynaptic iGluRs to modify electrical activity and thus control navigation. We will evaluate postsynaptic currents, electrical behavior and calcium transients in different mutant backgrounds, and link these parameters to how C. elegans navigates gradients of sensory information. In these studies, we will precisely map presynaptic sensory inputs to specific downstream interneurons and, using optogenetic strategies, determine how these inputs are integrated to control navigation. Our studies will provide a detailed molecular-based understanding of circuit function that can be used to generate testable hypotheses in more complex vertebrate circuits. We predict that what we learn from our proposed studies will have immediate relevance to ongoing studies of glutamatergic neurotransmission and the control of circuit function in vertebrates. Thus, our studies could contribute to new diagnostic or therapeutic modalities for neurological or psychiatric disorders associated with altered circuit function.

? DESCRIPTION (provided by applicant): Summary This proposal requests R13 support for the founding meeting of the Gordon Research Conference (GRC) on Modulation of Neural Circuits and Behavior. Neural circuits control behavior, but these circuits are surprisingly plastic. Thus, neuromodulators can change the gain of circuits and even their function - biasing circuits to act in different modes. Scientists from diverse fields - biology, systems engineering, genetics, ethology, neurology and psychiatry - have increasingly recognized the central importance of neuromodulation for the control of behavior and the exciting links to translational neuroscience research. This inaugural GRC Conference is thus timely and unique because of its emphasis on attracting a multidisciplinary group of participants. The Conference will have a central galvanizing impact on the rapidly developing field of neuromodulation by bringing a new focus to the mechanism of action of dopamine, serotonin and various peptides and growth factors that have essential roles in regulating emotional and cognitive states. Defects in neuromodulatory pathways are increasingly implicated in multiple mental disorders, including depression, addiction and ADHD. Thus, a mechanistic understanding of the functional organization of modulatory circuits, the dynamics of modulatory signaling, the behavioral effects of various modulators, and the role of modulators in neuronal homeostasis, is essential for a fundamental understanding of brain function. Our conference is also unique because it will help bring together scientists from traditionally separate fields that explore the rich diversity of ecologicaly significant behaviors. Thus, the Conference will provide an opportunity for new synergisms between scientists working on modulation of neural circuits and behavior in vertebrate and invertebrate model systems. The meeting is particularly timely because the field of neuromodulation is ripe for transformative new approaches based on recent advances in genetic and optogenetic strategies for examining circuit function. Many of the recent advances in our understanding of neuromodulation have come from scientists in Australia, China, Japan, Korea and other Asian countries. Our conference will alternate between the United States and Hong Kong - ideal locations that will maximize the effectiveness of the Conference in promoting intensive exchange of ideas and techniques between American scientists and those from Europe and Asia. Thus, this GRC will be a driving force for emerging studies of neuromodulation in the United States. We expect that the 2015 GRC on Modulation of Neural Circuits and Behavior will shape future scientific directions and provide critical support for the mission of NIH, particularly NINDS and its sister institutes including NIMH, NIDA and NIA.

PROJECT SUMMARY/ABSTRACT One of the earliest changes in Alzheimer?s Disease (AD) is dysfunction of synaptic transmission, thus interfering with information processing by neuronal networks. However, despite intensive study, the factors contributing to synaptic dysfunction, and thus cognitive decline, are not understood. Thus, it is of fundamental importance to understand how candidate genes implicated in AD such as amyloid precursor protein (APP) and superoxide dismutase (SOD) disrupt synaptic signaling. The scientific premise of the current proposal is to generate animal models of AD and undertake a genetics-based, systems biology approach to gain a fundamental understanding of how AD changes neuronal function(s). In contrast to complementary efforts in other systems, what distinguishes the current proposal is single neuron resolution, a focus on real-time in vivo intracellular transport of synaptic receptors and APP, and a systematic effort to discover regulatory, homeostatic and gene expression pathways that control or modify synaptic receptors and neurotransmission. We have modeled the overexpression of SOD and APP in transgenic C. elegans to gain new insights into the pathophysiology of AD. In preliminary experiments, we observed striking disruption of synaptic function in transgenic worms that overexpressed either SOD-1 or APL-1 (C. elegans homologs of SOD and APP, respectively). In particular, we found that motor-mediated transport of AMPA-type ionotropic glutamate receptors and glutamate-gated currents were severely disrupted, leading to altered behavior of the animals. These results provide a new conceptual framework for investigating the pathophysiology of synaptic dysfunction in AD. In this proposal, we test mechanistic models of SOD-1 and APL-1 mediated disruption of synaptic function, and we outline a strategy to identify novel genetic modifiers that restore synaptic transmission in our transgenic models of AD. Because of evolutionary conservation of APP, SOD, synaptic proteins, microtubule-dependent motors and most intracellular signaling pathways, our studies will have immediate relevance to the pathophysiology of AD in humans. Additionally, we expect our studies will provide new therapeutic strategies, and entry points for the treatment of AD and other neurodegenerative disorders associated with APP and SOD.

Synapses control information processing by the nervous system, and dysfunction of synapses is associated with many neurological diseases and neurodegenerative disorders. In all nervous systems, glutamate is the primary excitatory neurotransmitter used to activate neurons. The goals of this study are to provide important, new mechanistic insights into the function of glutamatergic synapses, which will aid in our understanding of information processing by the brain and provide new avenues for the development of pharmaceutical therapies for nervous system disorders. Using a genetic platform based on the nervous system of the model organism C. elegans, we will study how peptide ligands, which signal via G-protein coupled receptors, regulate synaptic function mediated by NMDA-type ionotropic glutamate receptors (NMDARs). Synaptic NMDARs are involved in the pathophysiology of numerous psychiatric and neurological disorders. We propose an integrated multidisciplinary approach that combines in vivo electrophysiological analysis, behavioral studies and optogenetic to study the mechanism of action by which specific neuropeptides regulate NMDAR-mediated synaptic signaling. These studies have particular promise for a deeper understanding of nervous system plasticity, and behaviors such as learning and memory. Our studies will reveal new targets for the development of new drugs and novel therapeutic strategies for disorders of nervous system function.