Marcelo Wood - US grants

DESCRIPTION (provided by applicant): It has long been appreciated that gene transcription is required for long-term memory storage, but only recently has it become clear that transcriptional regulation for memory processes involves the concerted action of multiple transcription factors and coactivators that interact with chromatin, a protein complex that packages DNA. Originally thought to be static and structural in purpose, chromatin is now known to be very dynamic, exerting precise control over gene expression. The idea that chromatin remodeling may regulate gene expression for memory processes has gained considerable attention recently through the study of enzymes that are involved in chromatin remodeling, in particular, histone acetyltransferases (HATs) and histone deacetylases (HDACs). For example, our previous research demonstrated that CREB-binding protein (CBP), a potent HAT and transcriptional coactivator, is critical for long-lasting forms of synaptic plasticity (the activity- dependent change in the strength of neuronal connections) and long-term memory. In this proposed research program, we continue to examine our central hypothesis that enzymes involved in chromatin remodeling are essential for gene expression involved in memory processes. Our preliminary data demonstrate that HDAC inhibitors (small molecule antagonists that block HDAC activity and induce a histone hyper-acetylated state) enhance synaptic plasticity and memory storage. Further, we find that HDAC inhibitors enhance memory processes via a defined molecular mechanism. To examine the effect of HDAC inhibitors on memory storage and define the molecular mechanism underlying the modulation of memory storage by HDAC inhibitors we propose three specific aims. In specific aim 1, we will examine how HDAC inhibition affects memory. In specific aim 2, we will define the underlying molecular mechanism by which HDAC inhibition enhances memory. In specific aim 3, we will examine how chromatin remodeling regulates gene expression during memory consolidation. Results from these experiments promise to significantly contribute to our understanding of how chromatin remodeling via histone modification regulates gene expression required for long-lasting forms of memory. Chromatin remodeling is considered a form of `epigenetic'regulation, in which gene expression is regulated without altering the DNA code, and may have long-lasting effects. Sustained epigenetic mechanisms of gene regulation in neurons have recently become central to several cognitive disorders including mental retardation, depression, and schizophrenia. PUBLIC HEALTH RELEVANCE: It has become clear that transcriptional regulation for memory processes involves the concerted action of multiple transcription factors and coactivators that interact with chromatin, a protein complex that packages DNA. Chromatin remodeling is considered a form of `epigenetic'regulation, in which gene expression is regulated without altering the DNA code, and may have long-lasting effects, an idea that has become central to understanding the molecular mechanisms underlying several cognitive disorders including mental retardation, depression, and schizophrenia. The experiments in this research proposal are focused on understanding how chromatin remodeling regulates gene expression required for memory processes.

[unreadable] DESCRIPTION (provided by applicant): A common finding from studies of drug abuse is that exposure to the context in which drug use occurs can trigger relapse, resulting in an increase in drug-seeking behavior and subsequent drug use. A major goal of interventions designed to eliminate drug seeking therefore must be to eliminate the ability of contextual cues to elicit memories that result in relapse. Behavioral and neurobiological approaches to memory have identified extinction, in which the relation between the context and the drug is severed, as a way to eliminate conditioned behavior. A major challenge for extinction-based therapies, however, is that extinguished behavior often returns with time or after re-exposure to the drug. Thus, extinction-based behavioral interventions must focus on ways to enhance the development of extinction, as well as methods to make the extinction memory long- lasting, causing persistent suppression of the original context-drug association. At a molecular level, studies of memory and extinction have demonstrated the necessity of gene transcription for long-term memory storage. Our research has found that regulation of gene transcription necessary for long-term memory formation involves the concerted action of multiple transcription factors and cofactors that interact with chromatin, a protein complex that packages DNA. Chromatin modification is a main mechanism of epigenetic gene regulation, which is emerging as a major molecular pathway involved in the transcriptional regulation of gene expression required for synaptic plasticity and memory storage. Epigenetic gene regulation has been shown to underlie persistent long-term changes at the cellular level as well as the behavioral level. Importantly, in animal models of addiction, chronic drug exposure induces stable chromatin modification resulting in maintained gene expression, which is thought to drive persistent changes in behavior. Considering the substantial overlap in the circuitry involved in drug addiction and learning and memory pathways, the focus of this grant application is to modulate learning and memory pathways in order to extinguish context-drug associated memories. We will use a combined behavioral, pharmacological, and genetic strategy to examine ways to enhance the development of extinction of cocaine-induced conditioned place preferences to cause persistent suppression of the original context-drug association. In Specific Aim 1, we will determine the best temporal pattern of context presentations to extinguish context-cocaine associations using the conditioned place preference (CPP) procedure. In Specific Aim 2, we will examine the behavioral and molecular consequences of administration of systemic or intra-hippocampal drugs that relax chromatin structure, thereby enhancing gene transcription during extinction of cocaine-induced CPP. In Specific Aim 3, we will examine the effects of inhibiting a chromatin modifying enzyme called CREB-binding protein (CBP), which relaxes chromatin structure, through genetic mutations and focal deletions of CBP, thereby inhibiting transcription during extinction of cocaine-induced CPP. This novel approach promises to elucidate behavioral and epigenetic mechanisms of extinction and will allow us to identify further molecular targets and brain systems for pharmacological interventions. [unreadable] [unreadable] PUBLIC HEALTH RELEVANCE: Cocaine addiction is a major public health problem in the United States. In this project, we examine behavioral and pharmacological interventions in a mouse model of cocaine seeking that may help reverse cocaine seeking and reduce relapse. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): One of the alluring aspects of examining the role of chromatin modifications in modulating transcription required for drug seeking behavior is that these modifications may provide transient and potentially stable epigenetic marks in the service of activating and/or maintaining transcriptional processes. These in turn may ultimately participate in the molecular mechanisms required for neuronal changes subserving long lasting changes in behavior. As an epigenetic mechanism of transcriptional control, chromatin modification has been shown to participate in maintaining cellular memory (e.g., cell fate) and may underlie the strengthening and maintenance of synaptic connections required for long-term changes in behavior. Epigenetics has become central to several fields of neurobiology where researchers have found that regulation of chromatin modification has a significant role in epilepsy, drug addiction, depression, neurodegenerative diseases, and memory. The research in this proposal is focused on histone deacetylation, which is a mechanism by which gene expression is silenced. Histone deacetylases are key negative regulators of long-term memory formation, but their role in drug seeking behavior remains largely unexplored. The focus of Aim 1 of this grant proposal is to examine the role of histone deacetylase (HDAC) 3 in the acquisition of cocaine-induced conditioned place preference. HDAC3 is the most abundant class I HDAC expressed in brain. The approach involves genetically modified HDAC3-FLOX mice in which homozygous HDAC3 deletions can be generated using adeno-associated virus (AAV) expressing Cre recombinase. This method allows for the generation of spatially and temporally restricted HDAC3 deletions that avoid developmental and performance issues that arise from traditional knockout mice or even most transgenic mice. The focus of Aim 2 is to examine the ability of a novel class of HDAC inhibitors that are selective for specific HDACs to facilitate extinction of drug seeking behavior. In both aims, histone modifications in brain sections will be examined using epifluorescent microscopy, which allows one to determine how HDAC3 directly/indirectly regulates several histone modifications of interest at the level of individual neurons. In summary, this research proposal describes an innovative genetic and pharmacological approach to examine the role of a key HDAC, HDAC3, in acquisition and extinction of drug-seeking behavior. PUBLIC HEALTH RELEVANCE: Results from this research proposal will significantly contribute to two aspects of drug seeking behavior. First, we will have a better understanding of a key molecular mechanism by which neurons make drug-induced long-lasting changes correlating with persistent changes in behavior. Second, we will explore the ability of novel inhibitors of these key molecular mechanisms to enhance the disruption of drug cue associations as a novel therapeutic approach.

DESCRIPTION (provided by applicant): The ability to learn, remember and recall information about the world is critical to every aspect of adaptive behavior. Despite striking recent advances in understanding neural mechanisms of memory, surprisingly little is known about how synaptic and nuclear events in neurons are coordinated in space and time in the induction of memory. This question forms the core of the present research program, which has the unique feature of combining the strengths of two independent laboratories, both of which utilize the marine mollusk Aplysia as a powerful preparation for studying the molecular basis of memory. The Carew group at UCI will contribute expertise in relating synaptic and molecular plasticity directly to bone fide learning and memory, and the Martin group at UCLA will contribute expertise in the analysis of signaling mechanisms between the synapse and the nucleus. The combined efforts of these two groups provide a unique opportunity to explore a fundamental question in cell biology, the mechanisms by which different compartments of a neuron communicate during memory formation. The project will be carried out at three interactive levels of analysis, captured in three Specific Aims: AIM I is a BEHAVIORAL ANALYSIS which will utilize a novel behavioral preparation that permits examining a monosynaptic sensory-motor (SN-MN) component of a reflex during intermediate-term and long-term memory formation, while simultaneously manipulating the local molecular environment of somatic and synaptic components of the reflex. AIM II is a SYNAPTIC ANALYSIS examining the SN-MN component of the reflex in the intact CNS in a preparation that allows specifying the contribution of somatic and synaptic events to synaptic facilitation. Here we will examine the mechanisms of (i) local induction of intermediateterm facilitation (ITF), (ii) synaptic induction of long-term facilitation (LTF), and (iii) conjoint synaptic and nuclear induction of LTF. AIM III is a MOLECULAR ANALYSIS examining the requirement for memory formation of (i) local translation at the synapse, focusing on two specific molecules, sensorin, a SN-specific neuropeptide, and cytoplasmic polyadenylation element binding protein (CPEB), a localized mRNA, (ii) facilitated importin-mediated transport of signals from synaptic compartments to the nucleus, and (iii) MARK signaling to the nucleus, CREB and C/EBP-mediated transcription, and induction of the immediate early gene C/EBP. Relevance to public health: Understanding the mechanisms whereby synapticallv generated signals trigger changes in gene expression in the nucleus during memory formation provides a means of identifying therapeutic targets for a variety of disorders including mental retardation, age-related memory loss and neuropsvchiatric diseases such as anxiety and mood disorders.

DESCRIPTION (provided by applicant): Our ability to encode the events that occur in our world, store that information, and then retrieve it at a later time is essential for survival. Our memory serves the essential capacity to integrate past events into current adaptive behavior. Thus, understanding brain processes involved in memory formation is of critical importance from a basic scientific perspective, as it can provide mechanistic insights into a fundamental aspect of cognitive behavior. The overarching goal of this research project is to elucidate brain mechanisms of memory by using a powerful model system, the marine mollusk Aplysia, to forge direct links between neuronal plasticity expressed at the cellular and molecular levels, and specific phases of enduring memory for sensitization expressed behaviorally. To accomplish this goal, there are three Specific Aims: A BEHAVIORAL ANALYSIS will be aimed at identifying the "rules" that govern memory formation for a range of temporally discrete forms of memory for sensitization. Of special importance will be the unique roles of different patterns of training in the formation of mechanistically distinct forms of memory. A SYNAPTIC ANALYSIS will be aimed at establishing synaptic analogs of the different forms of memory revealed in the Behavioral Analysis, and determining the synaptic mechanisms that are recruited into play in forming these diverse memories. A MOLECULAR ANALYSIS will be aimed at identifying "molecular profiles" for different forms of memory by examining the molecular cascades (the genes, messages and proteins) that are involved in altering synaptic strength during memory formation. Relevance to public health: The importance of understanding brain mechanisms underlying memory can be especially appreciated in cases where memory is impaired, such as in Alzheimer's Disease, Post-Traumatic Stress Disorders, and in victims of accidents or strokes. Thus a major challenge in mental health is to achieve a basic understanding of the brain mechanisms that are engaged in normal memory formation, and how those mechanisms are impaired when memory is compromised by disease or injury. Such an understanding is essential for developing effective therapies for cognitive problems involving memory impairment.

DESCRIPTION (provided by applicant): In this proposal, we examine for the first time an epigenetic mechanism called nucleosome remodeling and how it regulates coordinate gene expression required for cocaine-induced memory formation. The nucleosome is the repeating unit of chromatin and fundamental to the compaction of genomic DNA. Nucleosome remodeling complexes modify chromatin structure and regulate expression by repositioning nucleosomes at the promoters of genes. Recent human exome sequencing studies have identified subunits of the polymorphic BAF complexes (mammalian SWI/SNF nucleosome remodeling complex) that are frequently mutated in sporadic mental retardation and sporadic autism. Moreover, de novo mutations in various subunits of neuron-specific Brg1- associated factor (nBAF) nucleosome remodeling complex have been implicated in Coffin-Siris and Nicolaides-Baraitser syndromes, both of which are associated with intellectual disability. Together, these studies suggest that nBAF function is necessary for normal cognitive function. Although an important topic in other fields (e.g. yeast genetics and cancer), nucleosome remodeling has received little attention in neuroscience. However, a major discovery was the identification of the first neuron-specific BAF complex, which was subsequently found to regulate gene expression required for the conversion of precursor cells into terminally differentiated neurons. Importantly, the nBAF complex has a subunit, BAF53b, which participates in making nBAF neuron- specific. This subunit is both neuron and nBAF complex specific, making it an ideal target for investigating the potential contributions of nBAF to synaptic physiology and behavior. Building on this point, we propose to test the hypothesis that BAF53b, after playing a key role in neuronal fate decisions during development, continues to regulate gene expression and does so in a manner critical to adult memory processes as well as cocaine-induced memory formation. We propose three specific aims to test this hypothesis. In Specific Aim 1, we will use genetically modified mice to examine the role of BAF53b in long-term memory. In Specific Aim 2, we will use next generation sequencing, RNA seq, and chromosomal conformation capture 3C to determine what gene expression profiles are being regulated by BAF53b and chromatin looping during memory consolidation. In Specific Aim 3, we will determine how cocaine regulates coordinate gene expression via BAF53b-dependent nucleosome remodeling and chromatin looping during cocaine-induced memory formation. Together, the work under these specific aims will elucidate the contributions of BAF53b and the nBAF complex in general, to memory processes, and more specifically to cocaine-induced memory formation as a precursor event to persistent drug-seeking behavior.

DESCRIPTION (provided by applicant): Intellectual disorders are characterized by impairments in cognition, social behaviors, and communication. Recent human exome sequencing studies have identified subunits of the polymorphic BAF complexes (mammalian SWI/SNF chromatin remodeling complex) that are frequently mutated in sporadic mental retardation and sporadic autism. Moreover, de novo mutations in various subunits of neuron-specific Brg1-associated factor (nBAF) nucleosome remodeling complex have been implicated in Coffin-Siris and Nicolaides-Baraitser syndromes, both of which are associated with intellectual disability. Together, these studies suggest that nBAF function is necessary for normal cognitive function. Nucleosome remodeling complexes modify chromatin structure and regulate expression by repositioning nucleosomes at the promoters of genes. Why disturbances to chromatin remodeling via mutations in BAF complexes result in cognitive dysfunction is unknown. Although an important topic in other fields (e.g. yeast genetics and cancer), nucleosome remodeling has received little attention in neuroscience. However, a major discovery was the identification of the first neuron-specific BAF complex, which was subsequently found to regulate gene expression required for the conversion of precursor cells into terminally differentiated neurons. Importantly, the nBAF complex has a subunit, BAF53b, which participates in making nBAF neuron- specific. This subunit is both neuron and nBAF complex specific, making it an ideal target for investigating the potential contributions of nBAF t synaptic physiology and behavior. Building on this point, we propose to test the hypothesis that BAF53b, after playing a key role in neuronal fate decisions during development, continues to regulate gene expression and does so in a manner critical to adult plasticity and memory. We propose three specific aims to test this hypothesis. In Aim 1, we will use genetically modified mice to examine the role of BAF53b in long-term memory. In Aim 2, we will examine the role of BAF53b in long-term potentiation, a form of synaptic plasticity. In Aim 3, we will use next generation sequencing, RNA seq, to determine what gene expression profiles are being regulated by BAF53b during memory consolidation. Together, the work under these aims will elucidate the contributions of BAF53b, and the nBAF complex in general, to memory processes, and thereby significantly contribute to the understanding of how mutations in the complex lead to cognitive impairments in humans.

DESCRIPTION (provided by applicant): Learning and memory are absolutely essential to hearing. In their absence, comprehension would be impossible because no auditory information could be acquired or stored, and the recognition of previously heard sounds would be impossible. The long-term objectives of this research project are to discover the neural mechanisms that enable sounds to acquire meaning. The primary auditory cortex (A1) has been identified as a site for the acquisition and storage of auditory information. In general, encoding of behaviorally relevant sounds is strengthened as part of an overall functional remodeling of acoustic representation. For example, when a tone becomes a signal for rewarding or aversive stimuli, frequency tuning shifts toward or to the signal frequency, strengthening its encoding while weakening that of other frequencies. Tuning shifts can increase the area of signal representation in A1, and the amount of gain is directly proportional to both the cue's level of acquired importance and its memory strength. Such representational plasticity (RP) appears to be a substrate of auditory memory because it has the same attributes as memory itself. Engagement of mAChR's in A1 directly or by pairing tone with stimulation of the cholinergic nucleus basalis (NBstm) is sufficient to (a) produce RP, (b) actually implant specific behavioral auditory memory, and (c) increase neural synchrony (NSync). Further, increased synchrony predicts both RP in A1 and auditory memory. Thus, sounds may gain meaning via increased neural synchrony, which gives them greater effectiveness in communicating with target structures and strengthening their own representations. The specific aims of this project are to determine if increasing NSynch (gamma band oscillations and unit co-variances) during signal presentation can strengthen and increase the specificity of auditory memory, and/or enhance RP. Rats will be trained in auditory fear and reward tasks while a signal tone's induced neural synchronization is boosted via increasing loudness or brief concurrent NBstm. Studies will determine if increasing NSync can enhance memory strength and specificity, using custom designed training protocols that produce a modest level of RP and memory. If these experiments uncover neural synchrony as a mechanism sufficient to strengthen and/or produce specific auditory memory, then this project will have opened a pathway for remediation of auditory comprehension disorders.

? DESCRIPTION (provided by applicant): Exercise participation is an important determinant of cognitive health, particularly in aging. In fact, sedentary behavior has been singled out as the greatest modifiable risk factor causing cognitive decline and Alzheimer's Disease in the US, and ranks third worldwide. Despite the importance of physical activity and exercise, the exercise parameters that provide optimal cognitive health are not well defined, particularly with respect to the frequency and duration of exercise needed. Our data and others suggest that the exercise conditions that activate the underlying neurobiological mechanisms that enhance cognitive function can be flexible, and allow for intermittent and spaced exercise bouts. We propose the novel hypothesis that exercise establishes a type of molecular memory for the exercise stimulus, which regulates the frequency and duration of subsequent intermittent exercise that is needed to maintain cognitive benefits. The molecular memory remains during a defined temporal window, such that subsequent exercise (even low-level exercise normally sub-threshold to enhance long-term memory formation) can capitalize on the neurobiological events established by the initial experience of exercise, thus maintaining the benefits of exercise on cognitive function. We hypothesize that epigenetic mechanisms are fundamental for the molecular memory phenomenon, and serve to alter transcriptional processes through histone modifications to create stable changes in neuronal plasticity and giving rise to stable changes in behavior. Our goal in this proposal is to define the exercise parameters that establish a molecular memory, investigate the underlying mechanisms that enable exercise to more efficiently promote enhanced cognition, and explore if pharmaceutical manipulation can extend the molecular window established by exercise. Because benefits of exercise for improving cognition, particularly hippocampal function, rely in large part from induction of the key plasticiy molecule `brain-derived neurotrophic factor' (BDNF), we focus on BDNF induction and epigenetic modifications that control BDNF regulation. We propose three Aims. Aim 1 - Determine the effective exercise patterns and molecular memory temporal windows that result in long-term memory formation. Aim 2 - Determine the histone modification patterns resulting from exercise that establish a molecular memory for BDNF expression. Aim 3 - Determine if cognitive benefits of exercise can be prolonged by pharmacological manipulation of the epigenetic molecular memory established by exercise, using a novel selective histone deacetylase 3 (HDAC3) inhibitor. Overall, our research in this proposal will serve as a foundation for ultimately translating to humans the exercise parameters needed to maintain enhanced cognitive function.

? DESCRIPTION (provided by applicant): One of the alluring aspects of examining the role of chromatin modifications in modulating transcription required for long-term memory processes is that these modifications may provide transient and potentially stable epigenetic marks in the service of activating and/or maintaining transcriptional processes. These in turn ultimately participate in the molecular mechanisms required for neuronal changes subserving long-lasting changes in behavior. As an epigenetic mechanism of transcriptional control, chromatin modification has been shown to participate in maintaining cellular memory (e.g. cell fate) and may underlie the strengthening and maintenance of synaptic connections required for long-term changes in behavior. Epigenetics has become central to several fields of neurobiology where researchers have found that regulation of chromatin modification has a significant role in epilepsy, drug addiction, depression, neurodegenerative diseases, and memory. A current hypothesis is that specific patterns of chromatin modification may have specific effects on cellular function and subsequent behavior. Recent research suggests that our epigenome changes as a function of time, potentially leading to a shift in chromatin structure that makes gene expression more difficult, and thus forming long-term memories more difficult. In this proposal, we will examine the role of histone deacetylase 3 (HDAC3) in regulating gene expression during memory formation in the aging rodent. We have identified an age at which aging rodents fail to form long-term memory for object location, which is a form of memory susceptible to age-dependent decline in humans. HDAC3 is a powerful enzyme that generates a repressive chromatin structure that inhibits gene expression. During memory formation in young rodents, HDAC3 is removed from specific genes, resulting in long-term memory formation. However, this mechanism fails in aging rodents. We hypothesize that in the aging brain, HDAC3 develops abnormal activity in repressing gene expression. Our preliminary data support this hypothesis by demonstrating that homozygous focal genetic deletion of Hdac3 in aging rodents completely restores their long-term memory formation for object location. To fully test this hypothesis, we propose two aims. In aim 1 we will examine the role of HDAC3 in age-dependent long-term memory formation using genetically modified mice, viral approaches, and several behavioral tasks. In aim 2, we will use next generation sequencing including chromatin immunoprecipitation (ChIP) sequencing and RNA sequencing to identify HDAC3 target genes and how those genes are regulated throughout the lifespan by examining a number of different ages. Results from these experiments would demonstrate that HDAC3 is a key regulator of memory formation in the aging brain, which would lead to a significant conceptual advance in our understanding of how epigenetic mechanisms function in the aged brain and also identify potential for novel therapeutic design.

Project Summary/Abstract Clinical trials of Alzheimer's disease (AD) therapeutics have had the highest failure rate of any major disease, with only 1 compound approved of 244 compounds tested during 2002-2012 (Cummings, 2014). The majority of these compounds target known pathological processes such as beta amyloid (?-amyloid) processing or neurotransmitter system imbalance, and the failure of these trials highlights the urgent need for new biological approaches to treat AD. One new approach is to target the epigenetic mechanisms that are integral to learning and memory encoding. Histone H3 lysine 9 (H3K9) is a key target for methylation, with di and trimethylation of this site serving as transcriptional repressors. In preliminary data, we have discovered that H3K9 trimethylation (H3K9me3) increases with age in the hippocampus and is associated with cognitive decline in aged and AD transgenic mice. Notably, selective inhibition of the methyltransferase controlling H3K9 trimethylation (SUV39H1) with a newly developed pharmacological small molecule inhibitor (ETP69) dramatically improves hippocampus-dependent memory in aged and transgenic AD mice (but not young mice), opens repressive chromatin structure at genes required for memory formation, increases hippocampal BDNF levels, promotes transcription of NR4a2, and stimulates growth of dendritic spines, thus restoring key mechanisms commonly proposed for synaptic dysfunction with age and AD. This suggests that an approach for treating AD may be to target a specific epigenetic mechanism (H3K9me3) involved in the coordinate regulation of gene expression required for normal brain function. In this proposal we will build on our preliminary data and test the hypothesis that H3K9me3 levels and distribution regulated by SUV39H1 become unbalanced in the aging brain and exacerbate AD-related phenotypes. Such an unbalance may form the basis for the etiological complexity of AD. We will test the possibility that H3K9me3 is a key nodal repression point for cognitive decline associated with aging and AD, and that reducing H3K9me3 restores lost cognition in wild type and AD transgenic mouse models. We propose three Specific Aims: (1) How does H3K9 trimethylation in the hippocampus shift over the lifespan, do H3K9me3 levels on target genes predict declining hippocampus-dependent cognition, and are benefits of SUV39H1 suppression predicated by elevated H3K9me3 levels? (2) Is H3K9me3 accumulation accelerated by AD pathology (?-amyloid, oxidative stress) and is SUV39H1 suppression effective even in the presence of high pathology? (3) Using ChIP-seq and RNA-seq, what are the SUV39H1/H3K9me3 molecular events that drive the effects on cognition? Overall our studies will define a new mechanism controlling cognitive decline in aging and AD and profile an exciting new pharmacological approach to rebalance gene repression patterns and restore cognitive function.

): Nearly 100 million Americans were afflicted by at least one of more than a thousand neurological diseases, according to data for 2011. The risk of dementia increases exponentially with age, with disproportionate effects on blacks and Hispanics. Finding effective treatments for neurological disorders and strokes requires fundamental knowledge of the nervous system and the participation of a diverse workforce to enhance our overall creativity. In 2017, the U.S. Department of Education named the University of California, Irvine, (UCI) as a Hispanic-serving institution, meaning that one-quarter of the undergraduate student body identifies as Latino and that half of all students receive financial aid. More than 50 UCI faculty conduct research in neurosciences, primarily in the Departments of Neurobiology and Behavior (NBB), and Anatomy and Neurobiology. NBB, which was established in 1964, was the first neuroscience department in the world (five years before the formation of the Society for Neuroscience) and it is ranked among the top by the National Research Council. Over the last 18 years, the UCI Minority Science Programs (MSP) has developed innovative interventions to improve the academic excellence and to increase the number of underrepresented minority (URM) undergraduates being trained as the next generation of biomedical researchers. The objective of the program Broadening Research Achievement in Neurosciences (BRAiN) for a Diverse Workforce is to facilitate participants? career advancement from community college to UCI and from college to Ph.D. programs in neurosciences. The measurable objective is to increase by three-fold the number of URM undergraduates entering Ph.D. programs in neurosciences each year. Participants will spend two years being mentored and conducting research continuously. During the sophomore year, participants will join the MSP training laboratory, which is dedicated to developing original research projects while providing a nurturing and stimulating environment for URM students who have not taken upper division classes. Subsequently, participants will join one of the UCI laboratories dedicated to neurosciences. Participants will take courses in neurosciences, scientific writing and training in the responsible conduct of research. At the end of the program, participants will have attended 30 research talks by neuroscientists, developed strong quantitative reasoning skills (including computer programming), presented their research findings at two national conferences, participated as co-authors on a paper based on their research experience and gained admission to Ph.D. programs in neurosciences at top universities.

Project Summary There is a high comorbidity between substance use disorders (SUDs) and post-traumatic stress disorder (PTSD). A consequence of this comorbidity is that exposure to cues associated with trauma in a patient with PTSD may trigger relapse of drug seeking, even after successful treatment or periods of abstinence. Thus, a major goal of treatment for both PTSD and substance use disorders is to weaken the ability of environmental cues to induce relapse. One way to do this is through extinction techniques, in which the relation between the cue and the drug, or the cue and the traumatic memory, is severed. A major challenge for purely behavioral approaches to substance abuse and PTSD is that successful treatment with extinction often does not persist and relapse occurs with time, changes in context, or exposure to stress. Work in our laboratories has focused on manipulating epigenetic mechanisms to make the learning that occurs during extinction persistent, resulting in long-term weakening of fear responses (in the case of animal approaches to PTSD) and long-term elimination of drug-seeking (in animal approaches to substance abuse). However, our work, and most of the work in the general field of the neuroscience of extinction, comes from preclinical studies of basic mechanisms of extinction within approaches to PTSD (such as fear conditioning) or addiction (such as drug self- administration) in isolation; comparatively little is known about how learned fear and drug seeking interact at behavioral and molecular levels. We have developed a novel model of the comorbidity between PTSD and addiction in rodents that combines behavioral approaches that are well characterized at behavioral, circuit, and molecular levels. In this model, rodents receive exposure to a battery of shocks in one context and are tested for drug-seeking behaviors in a second context. Our preliminary data show that this exposure to a single battery of shocks causes persistent changes (>30 days) in responsivity to a mild stressor and results in increased cue-induced reinstatement of drug-seeking after extensive extinction. Thus, this approach captures a persistent context-independent change in drug-seeking that is not captured in other stress-induced reinstatement procedures and provides a strong basis for investigating, at a basic level, how reward and aversive processes interact across long periods of time and, at a translational level, how a single traumatic experience results in persistent effects on relapse after successful treatment. The three specific aims outlined in this application are designed to (1) elucidate the persistent behavioral and molecular effects of an acute trauma, (2) evaluate the post-trauma effects of pharmacological manipulation of a specific histone deacetylase (HDAC3) in circuits involved in extinction of fear and drug-seeking, and (3) to evaluate the mechanisms through which HDAC3 manipulations alter relapse after trauma. Our focus on epigenetic mechanisms holds significant promise for understanding how persistent changes in behavior are established following trauma, and provides a novel therapeutic avenue.

Abstract: We discovered microglia in the adult brain are dependent on signaling through the colony-stimulating factor 1 receptor (CSF1R), and identified several CSF1R inhibitors that crossed into the brain, leading to the elimination of most of the microglia. This remarkable phenomenon has been widely replicated and is now a standard in the field to explore microglial function in health and disease, and clinical trials are being conducted/planned as a result. We also found that we could eliminate microglia for as long as we continued treatment, but upon drug withdrawal, repopulation of the microglial tissue occurred rapidly from proliferating cells throughout the brain that formed a new microglial tissue in ~14 days. We found we could use this to ?reset? the inflamed microglial tissue after injury or in aging, and promote functional recovery/cognition. In this continuation, we seek to understand the source and properties of these repopulating cells that become microglia, and study how they modulate neuronal gene expression to rejuvenate the aged brain and fully restore long-term potentiation to that of a young animal. In addition, we describe a second slower source of microglial repopulation, that originates in specific brain niches ? the rostral migratory stream (RMS) and associated projecting axonal tracts. This ?alternative? repopulation is only unmasked by the complete elimination of microglia. These ?alternative? cells arise from unknown cells within these brain niches, and eventually can break out from the white matter tracts and fill the cortex/brain. These cells never attain the numbers, morphologies, or gene expression of microglia, but resemble microglia found in the RMS, which have pro-neurogenesis and increased phagocytotic capabilities than other microglia. We will determine the source of these ?alternative? cells, and the consequences of filling the brain with them, including if they have any therapeutic potential, in a mouse model of Alzheimer's disease.

Drug abuse and addiction represent major health issues both in the United States and worldwide. In the United States alone costs related to loss of work, crime, and health care exceed $700 billion a year. The field of addiction spans numerous disciplines including, but not limited to, medicine, psychiatry, neurobiology, pharmacology, public health, and law, illustrating the impact that drugs of abuse and addiction have on the human condition. We are currently experiencing an amazing growth of technologies yielding new insights into the biological effects of drugs of abuse and mechanisms for the development of dependence and addiction. At UC Irvine, the community of faculty and researchers studying the neurobiology of addiction is rapidly growing with support from the UC Irvine Center for Addiction Neuroscience (ICAN), a new NIDA P50 Center of Excellence called the Impact of Cannabinoids Across Lifespan (ICAL), and a new center focused on the medical and legislative challenges of legalized marijuana (Center for the Study of Cannabis). The goal of the proposed Training Program in Substance Use and Use Disorders is to train the next generation of innovative researchers in the field of addiction neuroscience by leveraging the exceptional strength in neuroscience at UCI, and the new centers focused on addiction research, to provide an educational and research experience that will position trainees as new leaders in the field. The training program is focused on predoctoral students and will provide the following: 1) a modern and interdisciplinary neurobiology of addiction course; 2) two courses related to cannabinoids and the endocannabinoid system that dovetail with the P50 ICAL research endeavors; 3) an annual addiction neuroscience symposium; 4) a training program annual retreat; 5) a scientific writing course; 6) a public speaking course provided by Activate to Captivate; 7) an addiction research seminar series; 8) a journal club; 9) instruction in methods for enhancing reproducibility; and 10) conference presentations. This will be the first training program on campus that is specifically focused on drugs of abuse and addiction. Together, the new centers focused on addiction bring together scientists and clinicians from over a dozen departments and four schools to address the grand challenges in this field, to train and educate the next generation of investigators and clinicians, and to disseminate important information to the public.

Project Summary/Abstract The MARC program at the University of California, Irvine UCI) is a critical component of the School of Biological Sciences Minority Science Programs (MSP) to increase the number and academic excellence of underrepresented undergraduates pursuing Ph.D. degrees and careers in biomedical research. The MARC program has had a transformative institutional impact by preparing an unprecedented number of underrepresented undergraduates that have obtained research doctorate degrees in biomedical sciences. MARC activities are designed to introduce participants to biomedical research, improve the academic preparedness and interest of participants in biomedical research. MARC scholars are introduced to the excitement of generating new biomedical knowledge in a nurturing environment that stimulates their critical thinking skills, self-confidence and increases students? self-identity as scientists. Independent research conducted under the direction of faculty mentors at UCI and at partner extramural sites serve as a core element to induce MARC scholars to pursue graduate school and research-focused careers. Over 70 faculty with experience training underrepresented undergraduates and with funded research programs serve as preceptors of MARC scholars. The MARC research training elements are integrated with the undergraduate curriculum and include, 1) individual career and academic advising, 2) a research faculty seminar series, 3) a journal club to introduce scholars to critical reading of current biomedical literature, 4) training in genomics, computational biology, statistics and methods to enhance reproducibility, 5) training in responsible conduct of research, 6) independent research directed by faculty mentors, 7) preparation to present oral presentations and posters at local and national conferences, 8) training in scientific communications, 9) workshops on application to graduate school, and 10) individual advice during the graduate school application process.

Project Summary The increased risk of Alzheimer?s Disease (AD) in women compared to men has been widely reported, including increased prevalence and also severity of cognitive impairment in women with AD than men. Women also exhibit an accelerated rate of impairment. However, there is considerable debate as to the physiological basis for this increased susceptibility. One potential key candidate mechanism that may underlie this vulnerability is differences in synaptic structure and function. To examine this question, we have opted to utilize a preclinical mouse model that exhibits endophenotypes of AD as well as normal aging mice. In particular, the familial AD 5xFAD transgenic mouse model recapitulates many AD characteristics, including an early aggressive amyloid-ß (Aß) pathology in the cortex and hippocampus, regions known to be necessary for learning and memory. We will test our hypothesis that synaptic density represents a key source of vulnerability to AD pathology in females as compared to males. Three distinct Aims will test this hypothesis. First, Aim 1 will evaluate the temporal progression of behavioral decrements in 5xFAD (male/female) mice as well as wild type (WT) mice from 4 through 24 mo of age. In addition, memory processes and also long-term potentiation, a form of synaptic plasticity thought to underlie learning and memory, will be assessed at the same ages. Second, Aim 2 will use clinically relevant magnetic resonance diffusion tensor imaging (dMRI) to map brain learning and memory circuits, probing the hippocampus and related brain structures for connectivity. Third, Aim 3 will explore the use of positron emission tomography (PET) imaging with an 18F radioligand to probe the synaptic marker, synaptic vesicle glycoprotein 2A (S2VA) in our WT and 5xFAD cohort. Preliminary studies have demonstrated loss of S2VA labeling in human AD patients, but have not explored sex-specific alterations. In sum, this research proposal will define the accelerated sex-specific changes in synaptic connectivity, density and physiological function that underlie the increased vulnerability of females when AD pathology is present. Moreover, we will identify when this vulnerability emerges with the future goal of intervening to either prevent or slow the progression of AD pathology.

Project Summary As a chronic neuropsychiatric disease, addiction is associated with specific molecular and functional neuronal plasticity changes that are triggered by repeated drug exposure leading to persistent changes in neuronal function and ultimately behavior. One powerful mechanism that may underlie aspects of this persistence is epigenetics. Epigenetics (i.e. modulation of gene expression that occurs through altered chromatin structure without fundamental changes to the DNA sequence itself) has been shown to establish stable changes in cell function. These stable changes in cell function can give rise to remarkable changes at many levels of observation (e.g. neuronal plasticity, behavior). Currently, we still know very little about the epigenetic mechanisms that could establish the persistence characteristic of drug-seeking behavior and whether such mechanisms may also be involved in reinstatement, or other relapse-like behaviors. This proposal is focused on examining the molecular and cellular mechanisms that may be involved in reinstatement. More specifically, we will focus on the role of the medial habenula (MHb) in cocaine-induced reinstatement of drug-seeking behavior. Most studies investigating the MHb have focused on nicotine seeking due to the high concentration of nicotinic acetylcholine receptors found throughout the medial habenula-interpeduncular nucleus pathway. Recent studies have begun to implicate the MHb in cocaine- associated behaviors, yet the role of the MHb in regulating reinstatement of cocaine-seeking behavior remains largely unknown. In fact, the MHb is rarely included in reward circuitry diagrams. Our recent findings demonstrate that the MHb is engaged by cocaine-primed reinstatement and the activity of choline acetyltransferase (ChAT) expressing neurons in the MHb is sufficient to drive reinstatement (Lopez et al., 2018). These results suggest that the MHb is a powerful regulator of relapse-like behaviors, which has important implications for understanding the reward pathways in the brain related to relapse. We will also examine the role of a histone deacetylase, called HDAC3, and a key HDAC3 target gene, called Nr4a2, in MHb-dependent reinstatement of drug-seeking. HDAC3 is a key negative regulator of memory formation and associative plasticity, which functions by repressing the expression of Nr4a2. NR4A2 is a transcription factor that regulates aspects of dopamine signaling during development. Both HDAC3 and NR4A2 are highly expressed in the MHb within ChAT expressing neurons, indicating these important regulators of memory processes have a central role in behaviors associated with MHb-dependent reinstatement. In this proposal, we will test the central hypothesis that the MHb is a key regulator of reinstatement of cocaine- seeking behavior, and does so in an HDAC3/NR4A2-dependent manner. Successful completion of these studies will demonstrate the key nature of the MHb in reinstatement, identify the physiological processes in the MHb responding to cocaine, and identify key epigenetic regulators of MHb function.