2017 Poster Abstracts
Plasma GDF15 level is elevated in psychosis and inversely correlated with severity.
Accumulating evidence suggests that GDF15 is a biomarker for ageing and morbidity of many somatic disorders such as cancer and inflammatory disorders. Recently, elevated serum GDF15 level was proposed as a marker for mood disorder. However, psychosis severity was not investigated in relation to plasma GDF15 levels. In the present study we measured GDF15 levels in plasma of 120 psychosis patients compared to 120 age and gender matched healthy controls. Within the patient cohort GDF15 levels were evaluated for association with age, gender, lifestyle factors, C-reactive protein levels, psychosis severity and metabolic disorder. Psychosis patients had elevated GDF15 levels compared to controls (medianPsychosis = 744 ng/mL, mediancontrols = 516 ng/mL, p < 0.001). Within the psychosis cohort, GDF15 levels, when corrected for age, metabolic health and lifestyle factors, were negatively correlated with psychosis severity (β = -0.218, p = 0.012). While GDF15 levels were elevated in patients versus healthy controls, the negative correlation between psychosis severity and GDF15 suggests a loss of anti-inflammatory GDF15 mediated functionality in severe psychosis. Study replication in larger cohorts will be necessary to assess the potential of GDF15 as a prognostic biomarker in psychosis.Masato Yoshizawa
Department of Biology, University of Hawaii at Manoa
The Evolution of a Series of Behavioral Traits is associated with Autism-Risk Genes in Cavefish
Animals can evolve through multiple behavioral shifts to adapt to a given environment. Each behavior is often polygenic and is under different genetic regulations. An essential question in evolutionary biology is thus whether a shared genetic basis facilitating the shift of polygenic behavioral cluster exist between animal species. Generating behavioral diversity can be a key to supply well-adapted individuals to the population under changing environments. The cave-dwelling Mexican tetra, Astyanax mexicanus has evolved multiple behavioral and morphological traits to adapt to perpetual darkness. Relative to surface-dwelling conspecifics, cavefish lost schooling ability (asocial), hyperactive and sleepless, adhere to a particular vibration stimulus (imbalance on the attention), behave repetitively, and show elevated stress hormone. Many of these traits are multigenic, and only a few are genetically correlated. Among the known animal models, the set of these cavefish traits mostly overlaps with the core symptom cluster of human autism spectrum disorder (ASD). Although the levels of complexity in each trait vary between human and fish, physiological and molecular processes of these innate behaviors are well conserved among vertebrates. In this study, we report rich parallels between underlying genetic changes of cavefish and human ASD.Amy Lin
Effects of reciprocal 22q11.2 copy number variation on cognition, behavior, and psychiatric symptomatology
Copy number variants (CNVs) at the 22q11.2 locus are highly penetrant risk factors for developmental neuropsychiatric disorders like schizophrenia (SCZ) and Autism Spectrum Disorder (ASD). While 22q11.2 Deletion Syndrome has been extensively investigated, little is known about the neurobehavioral consequences of duplications at 22q11.2. We previously showed that 22q11.2 gene dosage affects structural brain development. Here, we provide the first analysis, to our knowledge, of the effects of the number of genomic copies at the 22q11.2 locus on cognition, behavior, and psychiatric symptomatology.Alex Nord
Genomic changes in fetal cortex following maternal immune activation
Maternal immune activation (MIA) has emerged as a potentially strong contributor to neurodevelopmental disorders (NDDs), including autism and schizophrenia. Animal models of MIA provide the opportunity to identify the molecular signaling pathways that initiate the disease process and lead to NDD-related neuropathologies and behavioral deficits. We applied transcriptional and epigenomic profiling to identify changes in fetal mouse cortex across a time course following mid-gestational MIA via maternal poly(I:C) injection at E12.5. In order to reduce variability in the experimental model, we determined the effective dose of Poly(I:C) to induce reproducible levels of MIA and disease-relevant changes in offspring. Mice were bred and then injected with saline or poly(I:C). Prefrontal cortex was dissected from E12.5, E14.5, E17.5 and P0 from MIA and control offspring and then processed for RNA-seq. We also performed ChIP-seq examining histone modifications for E14.5 and P0 time points. While analysis is ongoing, we identified strong transient transcriptional signatures in fetal cortex. Via co-expression, we identified waves of changes induced by MIA. These changes included an initial acute signature suggesting activation of stress response pathways in the fetal brain, followed by alterations to proliferation and neuronal differentiation that emerged at E14.5 and peaked at E17.5. MIA-associated transcriptional changes largely resolved or were too variable to be robustly identified by birth (P0). Work validating the transcriptional findings and linking them to epigenomic changes is ongoing. We believe these genomic maps will provide insight into the molecular and developmental pathologies linking MIA and neurodevelopmental sequelae.Rinaldo Catta-Preta
Integrative Genetics and Genomics Grad Group, Dept of Neurobiology, Physiology and Behavior, University of California Davis
Towards a systems-level understanding of the gene regulatory wiring of interneuron specification
There is strong evidence that perturbation to neurodevelopment contributes to the etiology of disorders such as autism and schizophrenia. RNA-sequencing has emerged as a powerful approach for mapping cellular transcriptional identity during normal and pathogenic mammalian brain development. While transcriptional identity can present a rich picture of cellular diversity, gene expression alone may fail to predict future cell state during differentiation. Fate mapping shows that divergent fates of related cell types can be at least partly programmed before clear cell identity divergence during differentiation. We are examining how epigenomic state controls specification using an integrated genetic and genomic approach to study the origination interneuron subtypes in the basal ganglia during early brain development in the mouse. We seek to define how lineage specification is governed by the interaction between transcription factors (TFs), regulatory DNA elements, and chromatin structure. As an example, we have characterized the role of Nkx2-1 and Lhx6 in interneuron specification in the medial ganglionic eminence (MGE). We show that Nkx2-1 binding at distal regulatory elements is required to establish MGE-specific chromatin state and transcriptional regime and potentiate future gene expression patterns during differentiation. Combinatorial binding by Nkx2-1 and Lhx6 at distal enhancers directs activation of gene expression in cortical migrating interneurons as Lhx6 becomes activated. Moving forward, we are examining how epigenomic programming direct future steps in specification of these cell lineages and we have extended this genomic approach to build a combinatorial understanding of the activity of key TF pathways guiding interneuron specification. By integrating across genetic, genomic, and neuroanatomical approaches, we hope to decipher the genomic wiring guiding interneuron specification in the mammalian brain.[Kenneth Lim
Single Cell Integrated Flexible Interface (SCIFI)
Transcriptomic profiling captures systems-, pathway- and gene-level data regarding cellular identity, state and function, providing a powerful means to dissect normal and pathogenic biological processes. Recently, methods enabling transcriptomic profiling at single cell resolution have become accessible and widely adopted for characterization of the brain. Single cell RNA-sequencing (scRNA-seq) experiments generate high-dimensionality data, yet much of the richness of these datasets is lost in standard formats for publication and data sharing. In addition, re-analysis of these genomics data require specialized knowledge, preventing researchers that lack computational expertise from effectively examining the data. To address these issues and democratize scRNA-seq data analysis, we have developed the Single Cell Integrated Flexible Interface (SCIFI). SCIFI is an interactive online platform that enables users to analyze cellular relationships and patterns of gene expression for scRNA-seq datasets. SCIFI is designed using the R Shiny package to accompany scRNA-seq publications or to share data, stand-alone. It is hosted on the R ShinyApp servers and is free to use. It requires only sample information and a gene count matrix and gives users the ability to plot sample relationships using dimensionality reduction and clustering with control over parameters and co-expression patterns for genes of interest. SCIFI is available on our GitHub site and will continue to be updated to increase utility.Kristen Delevich
How do D2R-expressing MSNs in the dorsomedial striatum contribute to goal directed choice?
A lack of flexibility and insensitivity to negative outcomes is characteristic of multiple psychiatric disorders. Previous data from our lab and others implicate the activity of D2 receptor-expressing medium spiny neurons (D2R+ MSNs) of the dorsal medial striatum (DMS) in action selection, avoidance behavior, and response to negative feedback. In order to test the hypothesis that D2R+ MSNs of the DMS play an active role in inhibiting choice after negative outcomes, we employed the chemogenetic tools hM4Di and hM3Dq to selectively inhibit or excite D2R+ MSNs in mice during the recall and reversal phases of a 4-choice odor-based discrimination task. We predicted that inhibiting D2R+ MSNs would not affect recall of a learned contingency but would impair the ability to inhibit choosing the previously rewarded odor after reversal. However, we found that inhibition of D2R+ MSNs did not significantly alter recall or reversal performance. In contrast, chemogenetic excitation of D2R+ MSNs significantly impaired task performance during the recall phase: DIO-hM3Dq mice took more trials to reach criterion, due to more frequent selection of unrewarded odors. Our data therefore do not support the common working model in which the ‘braking’ activity of D2R+ MSNs in DMS is required for behavioral inhibition to enable flexible choice updating. Instead, our results suggest a more integrative role for activity in D2R+ MSNs of the DMS in encoding the relative value of multiple cues and/or choices. In follow up, we are investigating the role of activity of D1R expressing MSNs in this task.David Piekarski
UC Berkeley Department of Psychology
Pubertal hormones impact adolescent development of affective behavior and inhibitory neurotransmission, but not spine pruning, in frontal cortex.
Sex differences in anxiety and depression emerge shortly after the start of puberty, and early puberty has been associated with increased risk for anxiety and depression, particularly in girls. The medial frontal cortices are critical hubs in the expression of these psychopathologies and undergo considerable maturation during puberty and adolescence. Surprisingly few experiments have been performed that manipulate pubertal hormones in animal models to test for a causal relationship between puberty and the maturation of cortical circuits and affective or cognitive behavior. To address this gap, we have experimentally manipulated exposure to peripubertal gonadal hormones in age-matched mice and measured the development of frontal cortex neurotransmission, dendritic spine pruning, and affective and cognitive behavior. We find that gonadal hormones at puberty organize a long-lasting increase in inhibitory neurotransmission in layer 2/3 but do not alter spine dynamics or density on layer 5 pyramidal cells in the mouse medial frontal cortex. We also find that prepubertal gonadectomy decreases anxiety-like behavior in male but not female mice, demonstrating a sex difference in the role for the gonads in pubertal development of anxiety related behaviors. Finally, pre-pubertal gonadal hormone injection (to induce early puberty) in females speeds cognitive maturation, but has no impact on affective behaviors. In sum, our data do not support a simple role for gonadal hormones in the female bias in anxiety and depression after puberty. Instead, these data demonstrate that the pubertal rise in gonadal hormones in mice has circuit and sex specific effects. We hypothesize that the differential timing of puberty onset may alter the sequence and/or phase relationship in the maturation of neural circuits. We further speculate that stress and social factors may interact with circuit maturation to confer vulnerability to psychopathology at this developmental stage.Linda Su-Feher
University of California Davis, Center for Neuroscience
Transcriptional programming of interneuron specification in mouse basal ganglia
The basal ganglia is an anatomical region in the embryonic brain that contains the caudal, lateral, and medial ganglionic eminences. The eminences, which function as progenitor zones, give rise to inhibitory interneurons that populate the adult brain. Interneurons are vital components of brain circuitry; perturbation to interneuron specification has been linked to neurological disorders such as autism and schizophrenia. Inhibitory interneuron lineage specification is regulated by region-specific transcription factor networks in the ganglionic eminences. However, the transcriptional networks regulating early cell lineage specification in the eminences are not entirely known. Progenitor populations from embryonic day (E) 11.5 mice that have region-specific enhancer activity in the ganglionic eminences fate-map to distinct adult interneuron populations, suggesting the existence of fate-determination transcriptional pathways that are already active in early lineage specification of inhibitory interneurons. We aim to understand how transcription factor networks selectively regulate gene expression and genomic programming to control cell identity. We performed single-cell RNA-sequencing on cells from E11.5 caudal, lateral, and medial ganglionic eminences in order to characterize transcriptional networks that control and potentiate immediate and long-term cell fate decisions of populations arising in the basal ganglia. We identified major progenitor populations and cell types within the eminences, and are using guided and unguided approaches to identify the key transcriptional markers of transient cell states. This effort to identify the transcriptional networks regulating early lineage specification of inhibitory interneurons works toward constructing an understanding of the factors enabling interneuron diversity in the brain.Katelyn Benthall
UC Berkeley Department of Molecular and Cell Biology
Selective enhancement of striatonigral medium spiny neuron excitability following loss of Tsc1 in dorsolateral striatum leads to increased motor learning.
Autism spectrum disorder (ASD) has been proposed to result from alterations in excitatory/inhibitory synaptic balance leading to an inability to maintain or dynamically regulate network activity levels. Though the neural basis of ASD is not well defined, altered activity in basal ganglia (BG) circuits may be responsible for the repetitive and restricted behaviors (RRBs) that are a core symptom of the disorder. BG output depends on the balance of activity in the striatal direct and indirect pathways, and perturbations of this balance could result in motor abnormalities observed in ASD. Here we tested this idea by conditionally deleting the ASD-risk gene Tsc1, a regulator of the mTOR signaling pathway, from direct and indirect pathway striatal medium spiny neurons (dMSNs and iMSNs, respectively) to determine how this affects their morphological and functional properties. We found that dMSNs with Tsc1 deletion showed altered dendritic morphology and intrinsic excitability, as well as elevated synaptic excitation compared to control dMSNs. In contrast, Tsc1 deletion did not have a major effect on iMSN structure or function. Mice with Tsc1 deletion restricted to dMSNs displayed enhanced motor routine learning, which may reflect the same striatal circuit changes that give rise to RRBs in ASD patients. These findings suggest that the core repetitive motor symptoms of ASD could result from striatal direct pathway hyperexcitability.Jill Glausier
University of Pittsburgh
Cell Type-Specific Transcriptional and Ultrastructural Analyses of Oxidative Phosphorylation in the Prefrontal Cortex of Schizophrenia Subjects
Working memory, a core cognitive function impaired in schizophrenia, depends upon gamma oscillatory neuronal activity in the prefrontal cortex (PFC). Accordingly, individuals diagnosed with schizophrenia show lower power of gamma oscillations in the PFC during tasks that involve working memory.
Gamma oscillations emerge from the coordinated activity of layer 3 excitatory pyramidal cells and layer 3 inhibitory parvalbumin (PV) cells. Gamma oscillations have a particularly high energetic demand that is met by adenosine triphosphate (ATP) production via oxidative phosphorylation (OXPHOS) within pyramidal and PV cell mitochondria. In the PFC of schizophrenia subjects, layer 3 pyramidal cells have prominent reductions in the expression of genes in OXPHOS-related pathways.
OXPHOS can be regulated by two distinct processes, both of which have different effects on gene expression and mitochondria morphology. The first is the normal regulation due to ATP demand. ATP is produced via OXPHOS only upon demand, and never constitutively. Thus, less ATP demand due to reduced neuronal firing is associated with lower expression levels of electron transport chain (ETC) complexes that occurs in a correlated manner; and mitochondria within these neurons retain their Normal conformational state, characterized by the presence of a double membrane, organized crista, and homogenous matrix. The second possible regulatory process is pathological deficits in ETC enzyme expression. Defective OXPHOS eliminates the correlation across ETC complexes and between the subunits comprising an individual ETC complex; and mitochondria within these neurons exhibit a distinct Abnormal conformation, characterized by fragmented membranes, disorganized cristae, and a swollen matrix.
Either of these processes could account for the current OXPHOS findings in schizophrenia, and distinguishing between the two is critical to properly investigate and identify novel therapeutic targets for PFC dysfunction in the disease. To investigate which upstream factor is likely operative in the illness, we quantified transcript expression of ETC complex subunits in layer 3 pyramidal and PV cells, and performed ultrastructural analyses of mitochondrial conformation within pyramidal and PV axon boutons in layer 3 of the PFC in schizophrenia and unaffected comparison subjects.John Blair
University of California, Berkeley
A Human Neuronal Model of Tuberous Sclerosis
Tuberous Sclerosis Complex (TSC) is a multi-system neurodevelopmental disorder caused by heterozygous mutations in the TSC1 or TSC2 genes, whose protein products are essential negative regulators of mTORC1 signaling. Hallmark pathologies of TSC are cortical tubers, regions of dysmorphic, disorganized cells in the cortex that are thought to promote to epileptogenesis and contribute to cognitive dysfunction. To determine the developmental origin of tubers, we established novel human cellular models for TSC based on Cas9-mediated genome editing in human embryonic stem cells (hESCs). We generated isogenic heterozygous and homozygous cell lines with loss of function mutations in the TSC1 or TSC2 genes and differentiated them into two- and three-dimensional cultures of cortical neurons and glia. We find that mTORC1 signaling is normally strongly suppressed during neuronal differentiation and that complete loss of TSC1 or 2 results in deregulated mTORC1 activity leading to altered neuronal and glial development. Loss of either TSC1 or TSC2 leads to similar outcomes, with TSC2 deletion resulting in more severe phenotypes. Notably, heterozygous cells of either genotype display normal neuronal and glia development. Using hESCs with one loss of function and one conditional TSC2 allele, we find experimental support for the “second hit” hypothesis of tuber formation. We demonstrate that biallelic inactivation in a subset of neural progenitor cells is necessary and sufficient to give rise to dysmorphic tuber-like cells in human cortical spheroids. We show that neuronal differentiation and development can be rescued by the mTOR inhibitor rapamycin during critical windows of development. Together our findings advance our understanding of the developmental origins of tubers and establish a novel, genetically controlled human cellular model for studying the neuropathophysiology of TSC.
A. Ayanna Wade
University of California, Davis, Center for Neuroscience, Department of Neurobiology, Physiology, & Behavior
Reanalysis of Sequencing Data from CHD8 Experimental Models to Examine the Role of CHD8 in Neurodevelopment
Exome sequencing studies of patients with autism spectrum disorder (ASD) have identified recurrent de novo mutations to the gene encoding the chromatin remodeler CHD8. Mutations to CHD8 are suggested to drive neurodevelopmental pathology through global disruptions to gene expression and chromatin state, which could give insight into biological underpinnings of ASD. However, the biological processes and regulatory mechanisms affected by CHD8 dosage remain unknown. Several recent studies have aimed to characterize the developmental effects of CHD8 haploinsufficiency and knockdown in vivo in mice and in vitro in human cell lines. While these studies individually report the impact of decreased CHD8 protein, it can be difficult to reconcile published results due to variability in experimental design and model systems. Fortunately, most studies published to date include data from RNA-seq, with a subset also including ChIP-seq targeting CHD8, enabling unbiased genomic comparison of perturbations to CHD8 across in vivo and in vitro models. We reanalyzed published RNA- and ChIP-seq data on CHD8 derived from various tissue and cell types to characterize the functionality of CHD8 and identify common signatures of pathology, which together highlight the importance of CHD8 as a global regulator of gene expression. With the availability of genomic engineering and patient-specific cellular models, it will increasingly be standard practice to have multiple models capturing pathology associated with causal genes. The quantitative comparison across published datasets, as we have performed here, can provide valuable insight regarding critical mechanisms of pathology in neurodevelopmental disorders.Alannah Miranda
Study of 45 candidate genes identifies NRG1 and CACNG2 as associated with lithium response in bipolar disorder
This study sought to determine what genes and SNPs may be associated with a positive lithium response in bipolar disorder. The study consisted of two separate cohorts; a retrospective cohort, in which patients were surveyed about their past lithium use, and a prospective cohort, in which patients were placed on lithium monotherapy and observed for up to two years. 45 candidate genes and over 600 SNPs were analyzed for association with lithium response, using PLINK single SNP association analysis and LD clumping. One of the most highly associated genes in both studies was CACNG2, which recapitulates previous findings. A top CACNG2 SNP in the retrospective study was also found to be in LD with a top SNP in the prospective study. NRG1 was also found to be highly associated in both cohorts, which is intriguing as it is also one of the most highly associated genes with schizophrenia and as of yet, has not been found to be associated with lithium response.Hoyong Park
Neurophysiology laboratory, Konkuk University
MAPK-dependent presynaptic potentiation in the lateral habenula is responsible for depressive behaviors
The lateral habenula (LHb), recently proposed to be involved in depressive disorders.The abnormal potentiation of LHb neurons was previously shown to be mainly due to presynaptic alterations. However, the mechanisms of this presynaptic enhancement remain completely unknown. In this study, we observed that increase of release probability of LHb neurons in an animal models of depression. This presynaptic potentiation is temporarily variable and mediated by altered mitogen-activated protein kinase (MAPK)-dependent signaling upon the activation of glucocorticoid receptors (GRs). Interestingly, either exposure to a stressor or incubation with corticosterone abolished the circadian termporal oscillatory pattern of synaptic transmission in the LHb in MAPK-dependent manner, not in a protein kinase C (PKC)-dependent manner. The selective inhibition of MAPK kinase (MAPKK, MEK) activity in the LHb prevented the presynaptic potentiation of synaptic efficacy after the exposure to stressors and successfully reversed depressive symptoms including behavioral despair and helplessness in animal models of depression. Our study delineates the cellular and molecular mechanisms responsible abnormal presynaptic enhancement of LHb neurons in an animal model of depression, which critically participate in mediating depressive behaviours.Summer Thyme
Genetic analysis in zebrafish reveals shared neurobiological roles of schizophrenia-associated genes
Genomic studies have identified hundreds of schizophrenia-associated genes. While these studies have begun to converge on some common pathways, such as glutamate transmission, the functions of many of the identified genes are not well understood. Further complicating understanding of genetic susceptibility factors, disease-associated genomic regions often contain many genes, only one of which might be involved in the disease. Functional characterization of genes that contribute to schizophrenia has therefore become one of the major challenges in the field. We generated over one hundred zebrafish mutants for schizophrenia-associated genes and assessed brain activity, brain structure, and behavior. We identified mutants with phenotypes reminiscent of schizophrenia pathology, including several with decreased prepulse inhibition. Strikingly, multiple associated genes influence signals in the same brain regions, suggesting that seemingly unrelated genes may be involved in common underlying anatomical and functional pathways. Identifying connections between the genes themselves and between genes and schizophrenia-relevant behaviors also narrows the list of likely candidate genes. In particular, cnnm2 likely drives the association signal in a multi-gene locus. Taken together, our study identifies schizophrenia candidate genes with shared roles and lays the foundation for the large-scale analysis of genes involved in psychiatric disorders. Jingling Li
DMSO treatment promotes human pluripotent stem cell differentiation through an Rb-dependent mechanism
There are substantial variations in the propensity for differentiation across human pluripotent stem cell (hPSC) lines. This greatly restricts the potential of using hPSCs for stem cell-based therapies. Thus, understanding the underlying mechanisms regulating multilineage differentiation of hPSCs is of great value for regenerative medicine. In a prior study, we reported that culturing hPSCs in dimethylsulfoxide (DMSO) prior to differentiation promoted differentiation across all three germ layers. The DMSO treatment promoted activation of the retinoblastoma protein (Rb) and increased the percentage of hPSCs in the early G1 phase of the cell cycle. In this study, we provide further evidence that the DMSO treatment improves the efficiency of hPSC differentiation in an Rb-dependent manner and through the repression of cell cycle E2F-associated genes. Interestingly, the DMSO treatment increases chromatin accessibility of several early developmental genes in a cell cycle dependent manner. These results provide a novel mechanism in improving hPSC differentiation and also highlight important epigenetic modifications during differentiation. Using these mechanistic insights, we identify new tools to improve the prospects of using human pluripotent stem cells for therapy, particularly for neurodegenerative and neuropsychiatric disorders. Chen Tian
University of Southern California
An autism spectrum disorder-related de novo mutation hotspot discovered in the GEF1 domain of Trio
Recently, whole exome sequencing studies have fueled remarkable advances in our understanding of potential biological mechanisms underlying Autism spectrum disorder (ASD). By performing a meta-analysis of 4890 individuals with ASD-related disorders across several large databases, we have discovered a very large cluster of ASD-related de novo mutations in the Rac1 activating domain of the synaptic regulatory protein Trio. Trio, a Rho guanine nucleotide exchange factor (RhoGEF) recently implicated in Long-Term Potentiation (or LTP), promotes actin polymerization by directly activating the small GTPase Rac1. Accumulating evidence suggests that ASD-related behavioral phenotypes can be produced by Rac1 dysregulation and support the potential involvement of Trio in ASD.
Using a combination of electrophysiology and quantitative and super resolution imaging techniques we have found that ASD-related de novo mutations produce either hypofunctional or hyperfunctional forms of Trio. In accordance with pathological increases or decreases in glutamatergic neurotransmission observed in animal models of ASD, we find that these mutations result in either reduced synaptic AMPA receptor expression or enhanced glutamatergic synaptogenesis in CA1 pyramidal neurons of the hippocampus. Together, our findings implicate both excessive and reduced Trio activity and the resulting synaptic dysfunction in ASD-related pathogenesis, and point to the Trio-Rac1 pathway at glutamatergic synapses as a possible key point of convergence of many ASD related genes.John Donello
Rapastinel Antidepressant-like Activity is Independent of Medial Prefrontal Cortex Neurotransmitter Efflux
Rapastinel (Glyx-13) is a novel NMDA receptor modulator with glycine-like partial agonist properties. Rapastinel is in late-stage clinical development as an adjunct therapy for major depressive disorder. Esketamine, a noncompetitive NMDA receptor channel blocker, is known to produce rapid and sustained antidepressant effects in treatment-resistant patients with major depression. The rapid acting antidepressant activities of esketamine have been proposed to be dependent upon a presynaptic surge of extracellular glutamate, which is sufficient to subsequently activate pyramidal cell AMPA receptors. Both esketamine and rapastinel produce antidepressant-like effects in rodent models of depression but rapastinel does not exhibit esketamine-like CNS adverse effects. For example, rapastinel does not produce esketamine-like sedation and rewarding effects or disrupt sensorimotor gating in rodents (Burgdorf et al, 2013). In the present study, we evaluated acute effects of rapastinel and esketamine on extracellular levels of dopamine and glutamate in rat medial prefrontal cortex (mPFC) using intracerebral microdialysis. The onset and the duration of antidepressant-like effects of rapastinel and esketamine were evaluated in the rat forced swim test (FST).Jacobo Albert
Universidad Autónoma de Madrid, Spain
Distinct brain regions subserve response inhibition in patients with borderline personality disorder and healthy controls
Although response inhibition is thought to be important in borderline personality disorder (BPD), little is known about its neural substrates. The present study aimed to provide insight into this issue by exploiting the high temporal resolution of event-related potentials (ERP) and the spatial information of source reconstruction. Forty adults (20 patients with BPD and 20 healthy comparison subjects) performed a modified go/nogo task that allowed us to better isolate the brain activity specifically associated with the suppression of a motor response. Patients with BPD made more commission errors (failed inhibitions) than controls, suggesting that they had greater difficulty in withholding the response. Moreover, source reconstruction analyses revealed that patients with BPD activated posterior parietal regions (precuneus) more than controls during response inhibition, whereas controls activated prefrontal regions (presupplementary motor area, preSMA) more than BPD patients. This dissociation was supported by a significant Region (precuneus, preSMA) × Trial Type (Nogo, Go) × Group (BPD and control) interaction, confirming that distinct brain regions support response inhibition in BPD patients compared to healthy subjects. Such activation pattern differences were observed during the time range of P3, the ERP component most closely related to the inhibitory process itself. These results provide neural and behavioral evidence for impaired non-emotional response inhibition in BPD.Giuliana da Silva Zuccoli
Laboratory of Neuroproteomics, Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, Brazil
Mitochondrial and Nuclear Shotgun Proteome Analysis of the Posterior Cingulate Cortex from Schizophrenia Patients
Schizophrenia is a serious disorder caused by a combination of environmental factors with alterations in a number of genes. Functional MRI studies have shown the Posterior Cingulate Cortex (PCC) is dysfunctional in schizophrenia, and is suspected to be critically involved in the pathogenesis of the disorder. The PCC is situated in the medial part of the inferior parietal lobe and lies within the posteromedial cortex. It is mostly involved in the ability to retrieve memories and plan for the future, regulating the focus of attention, and its interactions with other brain networks may be important for conscious awareness. With this in mind, we aimed to investigate the subcellular proteome of mitochondria and nuclei of the postmortem PCC samples from schizophrenia patients compared to controls using shotgun proteomics. Analysis of the mitochondrial fraction revealed 26 proteins differentially regulated in schizophrenia which are involved in fatty acid beta-oxidation, ion transmembrane transport and metabolic process. Analysis of the nuclear fraction revealed 175 proteins differentially regulated in schizophrenia which are involved in DNA mismatch repair, DNA replication and DNA methylation. The possibility to study the subcellular proteome of different brain regions can help bring insight into the disturbances inherent to the disorder and possible therapeutic implications.Erin Spence
The in vivo proteome of developing synapses
Excitatory synapse formation during development involves the complex orchestration of both structural and functional alterations at the postsynaptic side, beginning with the formation of transient dendritic filopodia. Abnormalities in synapse development are linked to developmental brain disorders such as autism spectrum disorders, schizophrenia and intellectual disability. However, the molecular mechanisms that underlie excitatory synaptogenesis remain elusive in part because the internal machinery of developing synapses is largely unknown. Unlike mature excitatory synapses, there is currently no way to biochemically isolate the dendritic filopodia of nascent synapses. This lack of understanding is a critical barrier to our grasp of synapse development as well as the etiology of many neurodevelopmental disorders. We addressed this critical gap in our knowledge of synaptogenesis by developing cutting-edge chemicogenetic proteomic tools to reveal and quantify and synaptogenic proteome. From these results we have validated the role of a candidate found at developing synapses which is required for synapse maturation. This protein was previously unknown to be present at developing synapses, and through careful functional analysis we are one step closer to uncovering the mechanisms of early synapse formation.Huei-Ying Chen
Lieber Institute for Brain Development
Decreased spontaneous network activity in a mouse model of Pitt-Hopkins Syndrome, a rare form of autism spectrum disorder (ASD)
Pitt-Hopkins Syndrome (PTHS) is a rare form of autism spectrum disorder (ASD) that is caused by de novo mutation in one copy of the transcription factor 4 (TCF4) gene. This gene belongs to type 1 basic helix-loop-helix (bHLH) transcriptional factor family and is able to form homodimer or heterodimer with other members in this gene family for gene regulation in a tissue specific manner. Using a mouse model of PTHS that produces a truncated TCF4 protein (TCF4+/tr), we previously reported that medial prefrontal pyramidal neurons display intrinsic excitability deficit that are partially due to ectopic upregulation of SCN10a (Rannals et al., Neuron 2016). Here, we ask whether these cellular level excitability deficits have any impacts on synaptic transmission and network activity. We studied spontaneous neurotransmission with whole-cell patch clamp and network activity using Ca2+ imaging in acute prefrontal brain slices. We observed that TCF4+/tr neurons showed decreased frequency and amplitude of spontaneous excitatory synaptic currents (sEPSCs) onto pyramidal neurons. However, this effect was abolished in the presence of TTX suggesting that it was dependent on the generation of spontaneous action potentials. We also observed a significant reduction in the frequency of spontaneous inhibitory currents (sIPSCs) onto these pyramidal neurons. Similarly, this effect was sensitive to application of TTX, suggesting a dependence on the generation of spontaneous action potentials. To test for a generalized deficit in spontaneous action potentials in the prefrontal cortex of this PTHS mouse model Ca2+ imaging experiments are ongoing. These results herein together with intrinsic excitability deficit suggests pyramidal cells in this PTHS mouse model have an overall decrease in their ability to generate spontaneous action potentials and this leads to a generalized decrease in network activity. We hypothesize these excitability deficits in prefrontal cortical networks represent pathophysiology in PTHS that may underlie cognitive deficits observed in this patient population.Theresa Jacob
Maimonides Medical Center, NY
Differential Expression of Molecular Factors in Psychotic Spectrum Disorders: A Case-control Study
The identification of biological markers for psychosis holds the potential for objective testing methods. Previous studies have shown that schizophrenic patients have lower tPA and higher PAI-1 levels, however, their association with psychotic spectrum disorders remains elusive. The primary objective of this study was to assess the plasma levels of tPA and PAI-1 in patients undergoing psychotic episodes as compared to those in healthy controls. In this prospective case-control study, peripheral blood samples were collected from psychiatric inpatients and healthy age, gender and race-matched subjects. BPRS and CGI scales were administered and levels of tPA and PAI-1 were determined by ELISA. Data collected included anthropometrical measures, medical / psychiatric / psychosocial and substance abuse history and were analyzed using the SPSS statistical software. Preliminary data show that plasma levels of PAI-1 in patients with schizoaffective disorder was significantly lower as compared to that in control subjects. While previous biomarker research mostly focused on schizophrenia, we addressed the heterogeneity of psychotic spectrum disorder. Clarification of the role of tPA, its inhibitors and activators may open up new treatment modalities for these disorders.Vasiliki Karalis
University of California, Berkeley
Rptor deletion rescues TSC-related phenotypes in mice
Tuberous sclerosis complex (TSC) is a multi-system genetic disorder caused by disruption of the TSC1 or 2 genes. TSC is characterized by high rates of epilepsy and psychiatric conditions including autism and ADHD. The TSC1/2 genes form a protein complex that negatively regulates mTOR complex 1 (mTORC1) activity, and current pharmacological approaches to treat TSC use drugs such as rapamycin that block mTORC1 signaling. However, such drugs indirectly alter mTOR complex 2 (mTORC2) activity as well, resulting in potential unwanted side-effects. Our goal was to identify alternative approaches to reverse the biochemical and developmental changes associated with TSC1/2 loss.
In this study we tested whether deletion of the mTORC1 component Raptor, could rescue mTORC1 hyperactivity in in vitro and in vivo mouse models of TSC. Our results in hippocampal cultures demonstrate that genetic deletion of Rptor effectively rebalances mTORC1 signaling in the context of Tsc1 loss with minimal disruption of mTORC2. In addition, Rptor deletion rescues neuronal morphologic malformations resulting from loss of the Tsc1 gene. In vivo, mice with forebrain-specific loss of Tsc1 die prematurely between postnatal days 15 and 20. We find that heterozygous or homozygous deletion of Rptor rescues premature mortality in the Tsc1 knock-out mice in a gene dose-dependent manner. This work provides novel information regarding the relationships between TSC1/2, mTORC1, and mTORC2 in neurons and suggests an alternative therapeutic strategy for treating TSC and other mTOR-related disorders.Bernard Mulvey
Washington University in St. Louis School of Medicine
Sex Differences in Gene Expression and Activity of Noradrenergic Neurons in the Mouse Locus Coeruleus
Norepinephrine, originating from the locus coeruleus, acts broadly throughout the mammalian CNS as a neurotransmitter influencing wakefulness, focus, anxiety response, and memory consolidation. Here, we present results on sex differences in gene transcripts in the locus coeruleus of adult mice by using translating ribosome affinity purification (TRAP). We find that a prostaglandin receptor, PTGER3, is expressed more highly in female noradrenergic neurons, and that activation of PTGER3 with an agonist, sulprostone, inhibits firing of female, but not male, neurons of the locus coeruleus. We additionally explore the influence of sulprostone, delivered to waking mice directly to the LC via cannula, on stress-induced anxious behavior in the open-field test, confirming drug effects in female, but not male mice. Altogether, these results suggest that broad sex differences in transcriptional features of norepinephrine neurons may underlie sex differences in psychiatric disease incidence and in response to psychopharmacotherapeutics.Eminy Lee
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
Environmental enrichment rescues locomotion and social behavior deficits in MeCP2 T158A mutant mice through enhanced SUMOylation of MeCP2
The methyl-CpG-binding protein 2 (MeCP2) gene, MECP2, is an X-linked gene that encodes the MeCP2 protein and several MeCP2 mutations are linked to Rett syndrome (RTT). Among these mutations, T158M is the most common one. We have previously found that MeCP2 could be SUMO-modified by PIAS1 at Lys-412 and several MECP2 mutations identified in RTT patients all show decreased level of MeCP2 SUMOylation. Re-expression of MeCP2 or SUMO-modified MeCP2 in Mecp2-null neurons in the basolateral amygdala rescues the social interaction and fear memory deficits in Mecp2 conditional knockout (cKO) mice. Environment enrichment (EE) was shown to increase neuronal plasticity. In the present study, we examined whether increased SUMOylation of MeCP2 serves as a molecular mechanism of EE. We have adopted the MeCP2 T158A mutant mice as a mouse model for RTT. Results revealed that the MeCP2 T158A mutant mice showed significant impairment in locomotor activity, as indicated by reduced number of crossovers in an activity chamber. But EE effectively, although not completely, rescued this locomotor deficit. We also measured social interaction behaviors in these animals. Results revealed that the wild-type animals spent more time sniffing to stranger 1 than to the empty compartment in the chamber, but the MeCP2 T158A mice showed a significant reduction in the time sniffing to stranger 1 and the time these animals spent sniffing to stranger 1 and the empty compartment was similar. However, for MeCP2 T158A mice subjected to EE, the time they spent sniffing to stranger 1 was moderately increased compared to that of MeCP2 T158A mice, but the time they spent sniffing to stranger 1 and the empty compartment was apparently different. For the social novelty test conducted 10 min later, the wild-type animals spent more time sniffing to stranger 2 than to stranger 1. The MeCP2 T158A mice spent much less time sniffing to stranger 2 compared to the wild-type animals, but this behavioral deficit was rescued by EE. Further biochemical analysis revealed that the MeCP2 T158A mutant mice showed decreased level of MeCP2 SUMOylation in the amygdala, but EE rescued the reduction of MeCP2 SUMOylation. The amygdala tissue from these animals was also subjected to microarray analysis. Results revealed that the mRNA level of several genes, including bdnf and few genes involved in development, was markedly decreased in MeCP2 T158A mutant mice. We are now focusing on two of these downstream genes for further investigation. These results together suggest that enhanced MeCP2 SUMOylation is a molecular mechanism underlying EE that has a beneficial effect to the behavioral deficits observed in an animal model of RTT. [/vc_column_text][/vc_column][/vc_row][vc_row]Hanna Ollila
Department of Psychiatry and Behavioral Sciences Stanford University and Department of Public Health and the Institute for Molecular Medicine, University of Helsinki
Genetic interaction with pandemic flu vaccination reveals high effect genetic variants for narcolepsy
Narcolepsy type 1 is a severe hypersomnia affecting 1 of 3000 individuals. It is caused by a loss of neurons producing hypocretin/orexin in the hypothalamus. In 2009/2010, an immunization campaign directed towards the new pandemic H1N1 Influenza-A strain was launched and increased risk of narcolepsy reported in Northern European countries following vaccination with Pandemrix®, an adjuvanted H1N1 vaccine resulting in ~250 cases vaccination related in Finland alone. Using whole genome sequencing data of 2000 controls, exome sequencing data of 5000 controls and HumanCoreExome chip genotypes of 81 cases with vaccination related narcolepsy and 2796 controls, we, built a multilocus genetic risk score with established narcolepsy risk variants. We also analyzed, whether novel risk variants would explain vaccine related narcolepsy. We found that previously discovered risk variants had strong predictive power (accuracy of 73% and P<2.2*10-16) in vaccine related narcolepsy cases with only 4.9% of cases being assigned to the low risk category. Our findings indicate genetic predisposition to vaccine triggered narcolepsy, with the possibility of identifying 95% of people at risk.Marquis Vawter
University of California
Mitochondrial Complex I Deficiency in Schizophrenia and Bipolar Disorder and Medication Influence
Previous reports of mitochondrial dysfunction in the brain from subjects with schizophrenia (SZ) and bipolar disorder (BD) have shown decreased protein and transcript levels for mitochondrial genes, primarlily those related to Complex I, the first protein assembly of the electron transport chain. However, in vitro results have suggested the antipsychotic and antidepressant drugs used to treat these psychiatric disorders may be fully or partially responsible for these mitochondrial dysfunctions. In this study, we measured mitochondrial Complex I activity in postmorted brain tissue in parallel with measures of antipsychotic and antidepressent medications to gain a clearer understanding of these observer alterations. We additionally measured mitochondria DNA (mtDNA) copy number and the heteroplasmy rate of the 4,977 bp “common deletion” in the same samples. The aggregated protein concentration of Complex I was evaluated in brain tissue homogenate from the dorsolateral prefrontal cortex (DLPFC) of three groups (SZ, BD, and controls) and was used to standardize concentrations in the subsequent Complex I activity assay. Finally, regression analyses were performed to test for the effects of disease and psychiatric medications on Complex I activity while controlling for important covariates such as age, sex, and pH. Complex I activity was significantly decreased by 45% in SZ compared to controls (p =0.02) after adjusting for relevant covariates while no significant difference was found in BD. Additionally, two analyses of case only (SZ and BD) were conducted to evaluate the effect of drugs and age at disease onset. First, Complex I activity was significantly decreased (p = 0.01) in pooled cases that had detectable psychotropic medications and drugs compared to pooled cases that did not have detectable levels in toxicological assays. Second, subjects with an age of onset in teens (with no detectable psychotropic medications) showed significantly decreased (p<0.05) Complex I activity compared to subjects with an adult age of onset. Additionally, both SZ and BD groups displayed significant increases (p<0.05) of mtDNA copy number in the DLPFC compared to controls. Despite the observed differences in mtDNA copy number, the mitochondria common deletion burden was not significantly altered in SZ or BD, but this metric did have a significant and positive correlation with age in the brain (p<0.01). Taken together, this study suggests mitochondrial function is impaired in SZ brains, and supports prior reports that psychotropic medications can also result in mitochondrial dysfunction. The negative toxicology results of postmortem brain is an indicator of the absence of acute treatment, we cannot extrapolate that those patients were not exposed to psychiatric medications. Further studies of medication-free, early or first-episode psychosis patients, are needed to elucidate whether mitochondrial pathophysiology occurs independently of medication effects. Guijing Xiong
Synaptic Function Section, NINDS, NIH
Defective Presynaptic Transport Is Associated with Autism-like Social Interaction and Impaired Synaptic Plasticity
The formation, maintenance, and remodeling of synapses play an important role in the various degrees of synaptic plasticity. These processes require the targeted delivery of newly synthesized presynaptic cargoes from the soma to distal synapses. Time-lapse imaging studies have shown that vesicles of variable size and shape accumulate at synapses. Our previous studies revealed that syntabulin is an adaptor capable of linking the kinesin motor KIF5 and presynaptic cargoes, thus mediating axonal transport of presynaptic components essential for activity-induced formation of new synapses in developing neurons and maintenance of synaptic transmission in well-matured (up to 10 weeks) neurons (Su et al., Nature Cell Biology 2004; Cai et al., JNS 2007; Ma et al., JNS 2009). Autism is a highly inheritable neurodevelopmental disorder characterized by impaired social interaction, reduced communication, and increased repetitive behaviors. Recent studies suggest that genetic mutations that control the formation and maturation of synapses may be an important cellular basis of autism. These raise a fundamental question as to whether altered axonal transport is associated with the pathogenesis of autism. To address this issue, we generated a syntabulin cKO mouse model that displays a significant alternation of synaptic plasticity and autism-like social behaviors. Syntabulin cKO mice display impaired axonal transport of active zone proteins from the soma to developing presynaptic boutons in cultured hippocampal neurons, thus reducing synapse density. In addition, the mutant mice show a reduced frequency of miniature excitatory postsynaptic currents and impaired synaptic plasticity in acute hippocampus slices. Consequently, the mutant mice exhibit core autism-like traits including defective social recognition between strangers, reduced ultrasonic vocalizations, increased repetitive stereotypic behavior, and impaired spatial learning and memory. Thus, our study establishes for the first time that defective axonal transport contributes to the pathogenesis associated with synaptic and behavioral abnormalities in mice that bear similarities to human autism patients. Shweta Jain
Encephalopathy in Autism
Autism was discovered in 1943 by Leo Kanner who believed it to be caused by the emotional unavailability of the child’s mother. There is a growing body of literature that demonstrates an inflammatory etiology of autism. Evidence of inflammation in autism spectrum disorder (ASD) includes microglial activation and elevated anti-NMDA receptor antibodies, particularly in regressive autism. There is research suggesting that up to 69% of ASD patients have microglial activation and neuroinflammation. Variation in the pathogenesis of autism with both neuroinflammatory and psychosocial models calls for the use of differentiated therapy such as intravenous immunoglobulins and steroids in the former, and conventional symptomatic treatment for the latter. The objective of this translational literature review is to create a decision tree that incorporates the neuroinflammatory model and illustrates a more differentiated workup and management to mitigate ASD symptoms in certain patients. Michael Plach
Department of Chemistry and Pharmacy, Division of Molecular and Clinical Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
GPCR-mediated activation of ion-channels: focus on NTS1R – D2R and 5-HT2AR – D2R heterodimers
Various neurotransmitters like neurotensin (NT), dopamine (DA) and serotonin (5-HT) act via G protein-coupled receptors (GPCRs), the largest family of pharmacologically relevant membrane bound receptors. There is growing evidence for GPCR dimerization and the involvement of such receptor-receptor complexes in pathophysiological processes of neurological disorders. Here, we show the existence of neurotensin receptor 1 (NTS1R) dopamine D2 receptor (D2R) heterodimers in a neuronal cell line and in rat brain tissue. The D2R protomer remarkably influences phospholipase C (PLC) mediated NTS1R signaling resulting in the alteration of intracellular calcium signals. D2R antagonism leads to the inhibition of negative dopaminergic feedback. In contrary, analyzing the intracellular calcium response of both serotonin receptor 2A (5-HT2AR) D2R heterodimers and 5-HT2AR alone does not provide quantitative changes but a clearly oscillating signaling profile. In this case, coexpression of the D2R reduces the total amount of occurring oscillations in comparison to monomeric 5-HT2AR. Further investigation and comparison of different receptor-receptor complexes in terms of downstream signaling and intra-dimeric modulation promise more insight in highly interesting novel targets for the treatment of neurological diseases. Spencer Moore
University of California, San Diego
Setd5 loss of function reduces network connectivity in an animal model of autism
Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders characterized by repetitive behaviors and deficits in language and social interaction. ASDs represent one of the largest sources of childhood disability. Although rare monogenic forms have been identified, most cases lack an identifiable genetic basis. The current state of the field focuses on identification of novel risk variants and their convergence on synaptic-, cellular-, and network-level dysfunction in the autistic brain. The SETD5 gene encodes the SET-domain containing 5 protein (SETD5), loss-of-function mutations in which are known to cause the human 3p microdeletion syndrome of intellectual disability and confer risk of ASD. SETD5 has been proposed as a putative histone methyltransferase, based on its homology with other SET family members.
We hypothesized that SETD5 loss of function would contribute to connectivity deficits among cortical neurons, a known brain region of dysfunction in ASD. To this end, we sought to characterize the role of Setd5 on nervous system development in cellular, electrophysiologic, and behavioral assays from a heterozygous Setd5+/- mouse. First, primary cortical neurons were extracted from Setd5+/- or wild-type littermate P0 pups. Neurons were analyzed by immunocytochemistry, with deep-layer cortical neurons from Setd5+/- animals displaying significantly reduced synaptic density and neuritic outgrowth. To probe network-level connectivity changes, primary cortical neurons were cultured atop a multielectrode array (MEA), with serial recordings of spontaneous field potential activity. Compared to littermate controls, cortical neuron networks from Setd5+/- animals showed network connectivity abnormalities.
To expand upon our cell- and network-level findings, we sought behavioral correlates in adult animals. Based on existing animal models, we selected a battery of tests to assay important ASD-relevant behavioral domains. Setd5+/- animals showed no gross neurologic or motor defects; however, they did demonstrate alterations in several autism-relevant behaviors. These data from cellular-, network-, and behavioral-level assays converge on a picture of abnormal neurodevelopment. We believe the Setd5+/- animal represents a potential new model for ASD, which merits further investigation to uncover the molecular role of SETD5. Vincent Millischer
Neurogenetics Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
BDNF Val66Met and childhood adversity on response to physical exercise and internet-based cognitive behavioural therapy in depressed Swedish adults
The genetic effect of Brain-derived neurotrophic factor (BDNF) on treatment response in depression is not consistent in the literature. Childhood adversity is a known risk factor for depression which has been reported to increase depression susceptibility by interacting with BDNF genetic variation. We aimed to explore whether the BDNF variation Val66Met and childhood adversity (CA) predicted the treatment response to a 12-week intervention with physical exercise (PE) or internet-based cognitive behavioural therapy (ICBT) when compared with treatment as usual (TAU). A prospective cohort study nested within a randomised control trial was conducted using data from 547 participants with mild to moderate depression. Depression severity at baseline and follow-up was measured using the Montgomery-Åsberg Depression Rating Scale. Met allele carriers without exposure to CA and current antidepressant use showed higher treatment response to PE than Val homozygotes. There was no evidence to support that BDNF Val66Met or CA alone predicted treatment response to PE and ICBT. The Met carriers had higher serum mature BDNF level. These data suggest that Met allele carriers benefit more from PE treatment but only if they are not exposed to early adversity. Stephanie Zlatic
Geneological Proteomics of Menkes Disease Pedigrees Reveals Novel Connections with Parkinson ’s disease Gene, UCHL1/PARK5
Menkes Disease is a rare genetic disorder caused by mutations to the copper transporter ATP7A and characterized by neurodegeneration and defective neurodevelopment. Without functional ATP7A, these patients are unable to adequately absorb environmental copper from the gut. Copper depletion in tissues leads to diverse systemic and neurological phenotypes, such as widespread neurodegeneration. The molecular pathogenesis of ATP7A neurological phenotypes remain unknown. We used genealogical proteomics of Menkes patient family pedigrees to identify novel mechanisms affected in Menkes disease. Our bioinformatic analysis revealed mitochondrial function, and mechanisms of Parkinson’s disease, involved in connection with Menkes patient cells. We identified UCHL1/PARK5, a Parkinson’s disease gene, as a downstream effector of genetic defects in ATP7A regulating mitochondrial respiration. We propose that Menkes disease mechanisms share pathogenesis with familial forms of Parkinson’s disease. Kwanghoon Park
Konkuk University, Department of Biological Sciences, Seoul, South Korea
Fear-related brain regions of a fear extinction-impaired animal model of post-traumatic stress disorder
Post-traumatic stress disorder (PTSD), a common anxiety disorder, occurs less than 10 % of individuals after experiencing one or more terrifying accidents. One key symptom of PTSD is repeatedly re-experiencing the traumatic event. We found that a strain of mouse, 129S1/SvImJ (129S1) showed selective impairments in the fear extinction with no difference in auditory or contextual fear conditioning compared to C57BL/6 mice. To investigate brain regions involved in the impaired fear extinction, we systemically analyzed c-Fos expression after behavioral tests. Contextual fear conditioning increased c-Fos expression in the basolateral amygdala (BLA), central nucleus of the amygdala (CeA) and prelimbic cortex (PL) in both strains of mice, however, greater activation was observed in the basal amygdala (BA) and PL of 129S1 compared to C57BL/6. Fear extinction restored the c-Fos expression of C57BL/6 to the basal state while, 129S1 still expressed more c-Fos in the BA, centromedial amygdala (CEm) and PL. Compared to C57BL/6, 129S1 showed more c-Fos expression in the BA, CEm, centrolateral amygdala (CEl) and PL. In addition, we tested fear renewal by exposing mice to the conditioned tone twice in one of the three contexts, conditioning context, extinction context and novel context. We found selective c-Fos expression in two strains of mice depending on the renewal contexts as well as the strain of use. These results revealed the dynamic circuitry involved in different steps of fear memory formation, extinction and renewal thus provide a list of candidate brain regions to study the etiology and pathophysiology underlying PTSD. Polina Kosillo
mTORC1 critically controls midbrain dopamine neuron physiology and function
The lifetime incidence of dopamine (DA)-related neuropsychiatric and behavioral conditions is significantly elevated in TSC patients, yet little is known about the effects that TSC-causing genetic perturbations have on the dopaminergic system. To address this we have used the conditional Tsc1fl/fl mouse model to drive cell-type specific deletion of the Tsc1 gene from midbrain DA neurons. We characterized the behavioral and neurophysiological consequences of this manipulation using electrophysiology, fast-scan cyclic voltammetry and behavior analysis.
Embryonic Tsc1 loss selective to midbrain DA neurons led to a significant increase in their soma size, accompanied by reduced DA neuron excitability. Concurrent with reduced intrinsic excitability at the soma, we observed a ubiquitous and dramatic reduction in evoked DA release at axon terminals in the striatum, and pronounced changes in DA release probability. Further, while Tsc1 knock-out (KO) DA neurons have all the necessary components for DA synthesis and, in fact, produce more DA than wild-type counterparts, Tsc1 KO neurons fail to release DA upon stimulation. Together, these data point to ultrastructural changes in DA axon terminals, which are currently under investigation using electron microscopy. Notably, the deleterious effects of Tsc1 gene loss on DA neuron function could be rescued by partial genetic disruption of the mTOR-binding protein Raptor.
At the behavioral level, we find that DA neuron-specific loss of Tsc1 leads to cognitive inflexibility in an instrumental learning task, a phenotype that is often observed in patients with neuropsychiatric disorders.
Together our work shows that tightly regulated mTOR signaling is essential for normal DA neuron function, and sheds light on why DA-augmenting therapies may be helpful for TSC patients suffering from neuropsychiatric conditions. Masato Yoshizawa
Department of Biology, University of Hawaii at Manoa
Evolutionary parallels between cavefish and autism patients in behaviors and risk genes
Autism spectrum disorder (ASD) is diagnosed in 1-2% of the population, yet its complex genetic mechanism obstructs effective therapy. We report remarkable parallels between ASD patients and a cave-dwelling Mexican tetra, Astyanax mexicanus: cavefish are, relative to their conspecific surface-dwelling counterparts, asocial, hyperactive, sleepless, adhere to a particular stimulus, show repetitive behavior, and are potentially in a higher anxiety state. Our transcriptomic investigation revealed that in cavefish > 70% of the orthologues of the ASD-risk genes were significantly up- or down-regulated in a similar manner to ASD patients. In addition, ASD drugs mitigated cavefish’s behavioral adhesion, hyperactivity and/or sleeplessness. Diversification and selection pressure analyses revealed that, through evolutionary process, cavefish ASD genes are positively selected, as seen in human ASD genes, suggesting that cavefish may represent an accessible model for identifying the core gene-gene interactions and physiological processes of the ASD-like phenotypic cluster. Moinak Banerjee
Rajiv Gandhi Center for Biotechnology
Pharmacoepigenomic response of antipsychotic drugs on pharmacogenes
Variability in treatment response and side effects are major concerns in antipsychotic drug therapy. Epigenetic mechanisms in therapeutic response are increasingly becoming evident. Therefore, it is imperative to differentiate the role of host epigenetics from pharmaco-epigenetics in drug metabolism and transport. In a conventional clinical setup it is difficult to monitor the pharmacoepigenomic response of each individual drug as patients might be on multiple medications. To resolve this issue we first investigated the role of each individual antipsychotics and their combinations on the pharmacoepigenetic modulation of pharmacogenes, under in-vitro conditions and then validated the critical observations in clinical setting. The alterations in expression status of critical CYP genes and ABCB1 transporter gene were monitored, which was followed up by the promoter activation and methylation and their target microRNA expression, post antipsychotic treatment. Results indicate that ABCB1, CYP1A2 and CYP3A4 were upregulated by antipsychotic treatment and this regulation was controlled by their corresponding microRNAs as evident by the decreased expression of miR-27a and miR-128a under in-vitro conditions. This pharmacoepigenetic response was not modulated by methylation or genetic events. Similar pattern was observed in clinical setting but restricted to ABCB1 which was reflective of good therapeutic response. The study clearly demonstrates the pharmacoepigenetic role of antipsychotics on pharmacogenes in modulating therapeutic response. Jen Leddy
Gladstone Institute of Neurological Disease
Investigation of Rare Variants Associated with Familial Schizophrenia
Schizophrenia (SCZ) is a debilitating neuropsychiatric disorder in which both genetic predisposition and environmental factors are thought to play a causative role. It is considered to be just one of a spectrum of disorders that vary in clinical presentation, prognosis and outcome. SCZ affects approximately 1% of the worldwide population and incurs over $60 billion in annual healthcare costs. There is no treatment or cure for schizophrenia. Only a fraction of patients experiencing relief from positive psychiatric symptoms through anti-psychotic medications.
Although SCZ is a polygenic condition and hundreds of associated genetic variants have been identified, a number of genome-wide association (GWAS) and linkage analysis studies have identified key genetic variants that may be related to the disease process. One particular study involving a small, relatively isolated population of Palau, Micronesia, revealed several variants involved in critical neuronal functions that may be related to development of schizophrenia. Given that the prevalence of schizophrenia there is approximately double the prevalence worldwide, the study of these particular genetic variants may shed light on the basic molecular underpinnings of the disease process. A greater understanding of the disease process may reveal common molecular therapeutic targets that can be used to treat SCZ in the general population.
To begin characterization of these genetic variants, we transfected primary rodent cortical neurons plasmid constructs that overexpress or silence the targeted genes and their genetic variants. We then subjected the cells to longitudinal robotic microscopy, an optical, high-throughput, high-content phenotyping technology that captures numerous cellular features over time. These data allow us to analyze the cells for specific morphological attributes that may contribute to the disease process. We also used immunocytochemistry to assess the overall protein expression and localization of the various constructs. We will report the results of our findings on one of the rare SCZ variants during the meeting.”