IL1RAPL1 knockout mice show spine density decrease, learning deficiency, hyperactivity and reduced anxiety-like behaviours

Enhancement of memory and emotional functions by long-term ingestion of protease-treated porcine liver extract in mice

The relationship between diet and brain functions has garnered attention. Previous studies have shown that ingesting a protease-treated porcine liver decomposition product (PLDP) improves cognitive function in humans. In this study, we investigated the effects of PLDP ingestion on cognitive and emotional functions in mice. Mice were fed a PLDP-enhanced diet for 16 weeks and subjected to various behavioral assessments. PLDP ingestion enhanced long-term memory in Barnes maze test. Moreover, mice fed the PLDP diet exhibited reduced anxiety- and depression-like behaviors as evidenced by their performance in open-field, elevated plus maze, marble-burying, and forced swim tests. They also increased locomotor activity. RNA sequencing analysis of the brain tissue revealed substantial changes in gene expression, particularly in pathways associated with learning, memory, and anxiety regulation. Collectively, these results suggest that PLDP induces changes in gene expression associated with brain function, potentially contributing to the enhancement of cognitive function and psychological health. Furthermore, our findings not only enhance our understanding of the relationship between nutrition and brain function but also indicate the potential of interventions utilizing dietary components, such as PLDP, to support cognitive function and psychological health.

Duplication of the autism-related gene Chd8 leads to behavioral hyperactivity and neurodevelopmental defects in mice

Mutations in the gene encoding chromodomain helicase DNA-binding protein 8 (CHD8) are strongly associated with autism spectrum disorder (ASD). Although duplications of the chromosomal locus including CHD8 have also been detected in individuals with neurodevelopmental disorders, the contribution of CHD8 duplication to clinical phenotypes and the underlying mechanisms have remained unknown. Here we show that Chd8 knock-in (KI) mice that overexpress CHD8 as a model of human CHD8 duplication manifest growth retardation, microcephaly, impaired neuronal differentiation, and behavioral abnormalities including hyperactivity and reduced anxiety-like behavior. Chd8 overexpression affects the transcription and chromatin accessibility of genes related to neurogenesis, with these changes being associated with aberrant binding of CHD8 to enhancer regions. Furthermore, pharmacological intervention partially ameliorates the hyperactivity of Chd8 KI mice. Our results thus indicate that Chd8 KI mice recapitulate key features of CHD8 duplication syndrome in humans, providing insight into pathogenic mechanisms underlying neurodevelopmental disorders.

Mice Born to Mothers Fed a Diet High in Omega-6 Fatty Acids and Low in Omega-3 Fatty Acids During Pregnancy Exhibit Various Behavioral Changes Including Impaired Social Behaviors and Enhanced Recognition Memory

BACKGROUND

Modern dietary trends have led to an increase in foods that are relatively high in n-6 PUFAs and low in n-3 PUFAs. We previously reported that the offspring of mother mice that consumed a diet high in n-6 linoleic acid (LA) and low in n-3 α-linolenic acid (ALA), hereinafter called the LAhigh/ALAlow diet, exhibited behavioral abnormalities related to anxiety and feeding.

OBJECTIVES

We currently lack a comprehensive overview of the behavioral abnormalities in these offspring, which was investigated in this study.

METHODS

C57BL/6J virgin female mice at 11 wk of age were fed either a control diet or the LAhigh/ALAlow diet, mated at 13 wk of age, and maintained on their respective diet throughout gestation. At birth, the lactating mothers' diet was replaced with standard laboratory feed pellets. After weaning, the offspring continued to receive standard laboratory feed pellets, and both male and female offspring at 1-63 wk of age were analyzed using a comprehensive behavioral test battery (n = 6-14 offspring/group and offspring in each group were derived from ≥3 independent litters).

RESULTS

Both male and female offspring exposed in utero to the LAhigh/ALAlow diet exhibited impaired social behaviors, including the lower number of contacts with novel mice in the social interaction test [diet, F(1,15) = 9.807, P = 0.007, 2-way analysis of variance (ANOVA)], and also showed enhanced recognition memory in the object location test (diet, F(1,36) = 6.779, P = 0.013, 2-way ANOVA) compared with offspring exposed in utero to the control diet. In addition, compared with sex-matched controls, female offspring displayed hyperactivity in the open field test (F(1,36) = 6.097, P = 0.018, simple main effect analysis).

CONCLUSIONS

The maternal balance between dietary n-6 and n-3 PUFAs during pregnancy can have significant effects on the offspring's behaviors, lasting well into adulthood.

The Biological Changes of Synaptic Plasticity in the Pathological Process of Sepsis-associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a form of cognitive and psychological impairment resulting from sepsis, which occurs without any central nervous system infection or structural brain injury. Patients may experience long-term cognitive deficits and psychiatric disorders even after discharge. However, the underlying mechanism remains unclear. As cognitive function and mental disease are closely related to synaptic plasticity, it is presumed that alterations in synaptic plasticity play an essential role in the pathological process of SAE. Here, we present a systematic description of the pathogenesis of SAE, which is primarily driven by glial cell activation and subsequent release of inflammatory mediators. Additionally, we elucidate the alterations in synaptic plasticity that occur during SAE and comprehensively discuss the roles played by glial cells and inflammatory factors in this process. In this review, we mainly discuss the synaptic plasticity of SAE, and the main aim is to show the consequences of SAE on inflammatory factors and how they affect synaptic plasticity. This review may enhance our understanding of the mechanism underlying cognitive dysfunction and provide valuable insights into identifying appropriate therapeutic targets for SAE.

The fate of neuronal synapse homeostasis in aging, infection, and inflammation

Neuroplasticity is the brain's ability to reorganize and modify its neuronal connections in response to environmental stimuli, experiences, learning, and disease processes. This encompasses a variety of mechanisms, including changes in synaptic strength and connectivity, the formation of new synapses, alterations in neuronal structure and function, and the generation of new neurons. Proper functioning of synapses, which facilitate neuron-to-neuron communication, is crucial for brain activity. Neuronal synapse homeostasis, which involves regulating and maintaining synaptic strength and function in the central nervous system (CNS), is vital for this process. Disruptions in synaptic balance, due to factors like inflammation, aging, or infection, can lead to impaired brain function. This review highlights the main aspects and mechanisms underlying synaptic homeostasis, particularly in the context of aging, infection, and inflammation.

Human stem cell-based models to study synaptic dysfunction and cognition in schizophrenia: A narrative review

Cognitive impairment is the strongest predictor of functional outcomes in schizophrenia and is hypothesized to result from synaptic dysfunction. However, targeting synaptic plasticity and cognitive deficits in patients remains a significant clinical challenge. A comprehensive understanding of synaptic plasticity and the molecular basis of learning and memory in a disease context can provide specific targets for the development of novel therapeutics targeting cognitive impairments in schizophrenia. Here, we describe the role of synaptic plasticity in cognition, summarize evidence for synaptic dysfunction in schizophrenia and demonstrate the use of patient derived induced-pluripotent stem cells for studying synaptic plasticity in vitro. Lastly, we discuss current advances and future technologies for bridging basic science research of synaptic dysfunction with clinical and translational research that can be used to predict treatment response and develop novel therapeutics.

Rare variation in non-coding regions with evolutionary signatures contributes to autism spectrum disorder risk

Little is known about the role of non-coding regions in the etiology of autism spectrum disorder (ASD). We examined three classes of non-coding regions: human accelerated regions (HARs), which show signatures of positive selection in humans; experimentally validated neural VISTA enhancers (VEs); and conserved regions predicted to act as neural enhancers (CNEs). Targeted and whole-genome analysis of >16,600 samples and >4,900 ASD probands revealed that likely recessive, rare, inherited variants in HARs, VEs, and CNEs substantially contribute to ASD risk in probands whose parents share ancestry, which enriches for recessive contributions, but modestly contribute, if at all, in simplex family structures. We identified multiple patient variants in HARs near IL1RAPL1 and in VEs near OTX1 and SIM1 and showed that they change enhancer activity. Our results implicate both human-evolved and evolutionarily conserved non-coding regions in ASD risk and suggest potential mechanisms of how regulatory changes can modulate social behavior.

miR-181a expressed in the dorsal hippocampus regulates the reinstatement of cocaine CPP by targeting PRKAA1

Neuroadaptive changes in the hippocampus underlie addictive-like behaviors in humans or animals chronically exposed to cocaine. miR-181a, which is widely expressed in the hippocampus, acts as a regulator for synaptic plasticity, while its role in drug reinstatement is unclear. In this study, we found that miR-181a regulates the reinstatement of cocaine conditioned place preference(CPP), and altered miR-181a expression changes the complexity of hippocampal neurons and the density and morphology of dendritic spines. By using a luciferase gene reporter, we found that miR-181a targets PRKAA1, an upstream molecule in the mTOR pathway. High miR-181a expression reduced the expression of the PRKAA1 mRNA and promoted mTOR activity and the reinstatement of cocaine CPP. These results indicate that miR-181a is involved in neuronal structural plasticity induced by reinstatement of cocaine CPP, possibly through the activation of the mTOR signaling pathway. This study provides new microRNA targets and a theoretical foundation for the prevention of cocaine-induced reinstatement.

Genome-wide scans for selection signatures in indigenous chickens reveal candidate genes associated with local adaptation

Population growth and climate change pose challenges to the sustainability of poultry farming. The emphasis on high-yield traits in commercialized breeds has led to a decline in their adaptability. Chicken varieties adapted to the local environment, possessing traits that facilitate adaptation to climate change, such as disease resistance and tolerance to extreme weather conditions, can improve hybridization outcomes. In this study, we conducted an analysis of the population structure and genetic diversity of 110 chickens representing indigenous breeds from southern China and two different commercial breeds. Further, we performed comparative population genomics, utilizing nucleotide diversity and fixation statistics, to characterize genomic features of natural selection and to identify unique genetic traits and potential selection markers developed by indigenous breeds after adapting to the local environment. Results based on genetic diversity and population structure analyses showed that indigenous varieties exhibited high levels of genetic diversity. Commercial breeds that have been indigenously bred demonstrated higher levels of genetic diversity than those that have not, and breeds with different selection practices displayed significant differences in genetic structure. Additionally, we further searched for potential genomic regions in native chicken ecotypes, uncovering several candidate genes related to ecological adaptations affecting local breeds, such as IKBKB, S1PR1, TSHR, IL1RAPL1 and AMY2A, which are involved in disease resistance, heat tolerance, immune regulation and behavioral traits. This work provides important insights into the genomic characterization of ecotypes of native chicken in southern China. The identification of candidate genes associated with traits such as disease resistance, heat tolerance, immunomodulation, and behavioral traits is a significant outcome. These candidate genes may contribute to the understanding of the molecular basis of the adaptation of the southern native chicken to the local environment. It is recommended that these genes be integrated into chicken breeding programs to enhance sustainable agriculture and promote effective conservation and utilization strategies.

Differential contribution of canonical and noncanonical NLGN3 pathways to early social development and memory performance

Neuroligin (NLGN) 3 is a postsynaptic cell adhesion protein organizing synapse formation through two different types of transsynaptic interactions, canonical interaction with neurexins (NRXNs) and a recently identified noncanonical interaction with protein tyrosine phosphatase (PTP) δ. Although, NLGN3 gene is known as a risk gene for neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability (ID), the pathogenic contribution of the canonical NLGN3-NRXN and noncanonical NLGN3-PTPδ pathways to these disorders remains elusive. In this study, we utilized Nlgn3 mutant mice selectively lacking the interaction with either NRXNs or PTPδ and investigated their social and memory performance. Neither Nlgn3 mutants showed any social cognitive deficiency in the social novelty recognition test. However, the Nlgn3 mutant mice lacking the PTPδ pathway exhibited significant decline in the social conditioned place preference (sCPP) at the juvenile stage, suggesting the involvement of the NLGN3-PTPδ pathway in the regulation of social motivation and reward. In terms of learning and memory, disrupting the canonical NRXN pathway attenuated contextual fear conditioning while disrupting the noncanonical NLGN3-PTPδ pathway enhanced it. Furthermore, disruption of the NLGN3-PTPδ pathway negatively affected the remote spatial reference memory in the Barnes maze test. These findings highlight the differential contributions of the canonical NLGN3-NRXN and noncanonical NLGN3-PTPδ synaptogenic pathways to the regulation of higher order brain functions associated with ASD and ID.

Cytokines, synaptic plasticity and network dynamics: a matter of balance

The modern view of the immune system as a sensitizing and modulating machinery of the central nervous system is now well recognized. However, the specific mechanisms underlying this fine crosstalk have yet to be fully disentangled. To control cognitive function and behavior, the two systems are engaged in a subtle interacting act. In this scenario, a dual action of pro-inflammatory cytokines in the modulation of brain network connections is emerging. Pro-inflammatory cytokines are indeed required to express physiological plasticity in the hippocampal network while being detrimental when over-expressed during uncontrolled inflammatory processes. In this dynamic equilibrium, synaptic functioning and the performance of neural networks are ensured by maintaining an appropriate balance between pro- and anti-inflammatory molecules in the central nervous system microenvironment.

Altered motor learning and coordination in mouse models of autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with increasing prevalence. Over 1,000 risk genes have now been implicated in ASD, suggesting diverse etiology. However, the diagnostic criteria for the disorder still comprise two major behavioral domains - deficits in social communication and interaction, and the presence of restricted and repetitive patterns of behavior (RRBs). The RRBs associated with ASD include both stereotyped repetitive movements and other motor manifestations including changes in gait, balance, coordination, and motor skill learning. In recent years, the striatum, the primary input center of the basal ganglia, has been implicated in these ASD-associated motor behaviors, due to the striatum's role in action selection, motor learning, and habit formation. Numerous mouse models with mutations in ASD risk genes have been developed and shown to have alterations in ASD-relevant behaviors. One commonly used assay, the accelerating rotarod, allows for assessment of both basic motor coordination and motor skill learning. In this corticostriatal-dependent task, mice walk on a rotating rod that gradually increases in speed. In the extended version of this task, mice engage striatal-dependent learning mechanisms to optimize their motor routine and stay on the rod for longer periods. This review summarizes the findings of studies examining rotarod performance across a range of ASD mouse models, and the resulting implications for the involvement of striatal circuits in ASD-related motor behaviors. While performance in this task is not uniform across mouse models, there is a cohort of models that show increased rotarod performance. A growing number of studies suggest that this increased propensity to learn a fixed motor routine may reflect a common enhancement of corticostriatal drive across a subset of mice with mutations in ASD-risk genes.

Comparative population genomics analysis uncovers genomic footprints and genes influencing body weight trait in Chinese indigenous chicken

Body weight of chicken is a typical quantitative trait, which shows phenotypic variations due to selective breeding. Despite some QTL loci have been obtained, the body weight of native chicken breeds in different geographic regions varies greatly, its genetic basis remains unresolved questions. To address this issue, we analyzed 117 Chinese indigenous chickens from 10 breeds (Huiyang Bearded, Xinhua, Hotan Black, Baicheng You, Liyang, Yunyang Da, Jining Bairi, Lindian, Beijing You, Tibetan). We applied fixation index (FST) analysis to find selected genomic regions and genes associated with body weight traits. Our study suggests that NELL1, XYLT1, and NCAPG/LCORL genes are strongly selected in the body weight trait of Chinese indigenous chicken breeds. In addition, the IL1RAPL1 gene was strongly selected in large body weight chickens, while the PCDH17 and CADM2 genes were strongly selected in small body weight chickens. This result suggests that the patterns of genetic variation of native chicken and commercial chicken, and/or distinct local chicken breeds may follow different evolutionary mechanisms.

Rare variation in noncoding regions with evolutionary signatures contributes to autism spectrum disorder risk

Little is known about the role of noncoding regions in the etiology of autism spectrum disorder (ASD). We examined three classes of noncoding regions: Human Accelerated Regions (HARs), which show signatures of positive selection in humans; experimentally validated neural Vista Enhancers (VEs); and conserved regions predicted to act as neural enhancers (CNEs). Targeted and whole genome analysis of >16,600 samples and >4900 ASD probands revealed that likely recessive, rare, inherited variants in HARs, VEs, and CNEs substantially contribute to ASD risk in probands whose parents share ancestry, which enriches for recessive contributions, but modestly, if at all, in simplex family structures. We identified multiple patient variants in HARs near IL1RAPL1 and in a VE near SIM1 and showed that they change enhancer activity. Our results implicate both human-evolved and evolutionarily conserved noncoding regions in ASD risk and suggest potential mechanisms of how changes in regulatory regions can modulate social behavior.

Intrahippocampal injection of IL-1β upregulates Siah1-mediated degradation of synaptophysin by activation of the ERK signaling in male rat

Interleukin-1β (IL-1β) has been described to exert important effect on synapses in the brain. Here, we explored if the synapses in the hippocampus would be adversely affected following intracerebral IL-1β injection and, if so, to clarify the underlying molecular mechanisms. Adult male Sprague-Dawley rats were divided into control, IL-1β, IL-1β + PD98059, and IL-1β + MG132 groups and then sacrificed for detection of synaptophysin (syn) protein level, synaptosome glutamate release, and synapse ultrastructure by western blotting, glutamate kit and electron microscopy, respectively. These rats were tested by Morris water maze for learning and memory ability. It was determined by western blotting whether IL-1β exerted the effect of on syn and siah1 expression in primary neurons via extracellular regulated protein kinases (ERK) signaling pathway. Intrahippocampal injection of IL-1β in male rats and sacrificed at 8d resulted in a significant decrease in syn protein, damage of synapse structure, and abnormal release of neurotransmitters glutamate. ERK inhibitor and proteosome inhibitor treatment reversed the above changes induced by IL-1β both in vivo and in vitro. In primary cultured neurons incubated with IL-1β, the expression level of synaptophysin was significantly downregulated coupled with abnormal glutamate release. Furthermore, use of PD98059 had confirmed that ERK signaling pathway was implicated in synaptic disorders caused by IL-1β treatment. The present results suggest that exogenous IL-1β can suppress syn protein level and glutamate release. A possible mechanism for this is that IL-1β induces syn degradation that is regulated by the E3 ligase siah1 via the ERK signaling pathway.

RGS3 and IL1RAPL1 missense variants implicate defective neurotransmission in early-onset inherited schizophrenias

BACKGROUND

Schizophrenia is characterized by hallucinations, delusions and disorganized behaviour. Recessive or X-linked transmissions are rarely described for common psychiatric disorders. We examined the genetics of psychosis to identify rare large-effect variants in patients with extreme schizophrenia.

METHODS

We recruited 2 consanguineous families, each with patients affected by early-onset, severe, treatment-resistant schizophrenia. We performed exome sequencing for all participants. We checked variant rarity in public databases and with ethnically matched controls. We performed in silico analyses to assess the effects of the variants on proteins.

RESULTS

Structured clinical evaluations supported diagnoses of schizophrenia in all patients and phenotypic absence in the unaffected individuals. Data analyses identified multiple variants. Only 1 variant per family was predicted as pathogenic by prediction tools. A homozygous c.649C > T:p.(Arg217Cys) variant in RGS3 and a hemizygous c.700A > G:p.(Thr234Ala) variant in IL1RAPL1 affected evolutionary conserved amino acid residues and were the most likely causes of phenotype in the patients of each family. Variants were ultra-rare in publicly available databases and absent from the DNA of 400 ethnically matched controls. RGS3 is implicated in modulating sensory behaviour in Caenorhabditis elegans. Variants of IL1RAPL1 are known to cause nonsyndromic X-linked intellectual disability with or without human behavioural dysfunction.

LIMITATIONS

Each variant is unique to a particular family's patients, and findings may not be replicated.

CONCLUSION

Our work suggests that some rare variants may be involved in causing inherited psychosis or schizophrenia. Variant-specific functional studies will elucidate the pathophysiology relevant to schizophrenias and motivate translation to personalized therapeutics.

Modulation of Neural Networks by Interleukin-1

Interleukin-1 (IL-1) is an inflammatory cytokine that has been shown to modulate neuronal signaling in homeostasis and diseases. In homeostasis, IL-1 regulates sleep and memory formation, whereas in diseases, IL-1 impairs memory and alters affect. Interestingly, IL-1 can cause long-lasting changes in behavior, suggesting IL-1 can alter neuroplasticity. The neuroplastic effects of IL-1 are mediated via its cognate receptor, Interleukin-1 Type 1 Receptor (IL-1R1), and are dependent on the distribution and cell type(s) of IL-1R1 expression. Recent reports found that IL-1R1 expression is restricted to discrete subpopulations of neurons, astrocytes, and endothelial cells and suggest IL-1 can influence neural circuits directly through neuronal IL-1R1 or indirectly via non-neuronal IL-1R1. In this review, we analyzed multiple mechanisms by which IL-1/IL-1R1 signaling might impact neuroplasticity based upon the most up-to-date literature and provided potential explanations to clarify discrepant and confusing findings reported in the past.

Theacrine, a Potent Antidepressant Purine Alkaloid from a Special Chinese Tea, Promotes Adult Hippocampal Neurogenesis in Stressed Mice

Daily intake of tea has been known to relate to a low risk of depression. In this study, we report that a special variety of tea in China, Camellia assamica var. kucha (kucha), possesses antidepressant effects but with less adverse effects as compared to traditional tea Camellia sinensis. This action of kucha is related to its high amount of theacrine, a purine alkaloid structurally similar to caffeine. We investigated the antidepressant-like effects and mechanisms of theacrine in chronic water immersion restraint stress and chronic unpredictable mild stress mice models. PC12 cells and primary hippocampal neural stem cells were treated with stress hormone corticosterone (CORT) to reveal the potential antidepression mechanism of theacrine from the perspective of adult hippocampus neurogenesis. Results of behavioral and neurotransmitter analysis showed that intragastric administration of theacrine significantly counteracted chronic stress-induced depression-like disorders and abnormal 5-hydroxytryptamine (5-HT) metabolism with less central excitability. Further investigation from both in vivo and in vitro experiments indicated that the antidepressant mechanism of theacrine was associated with promoting adult hippocampal neurogenesis, via the modulation of the phosphodiesterase-4 (PDE4)/cyclic adenosine monophosphate (cAMP)/cAMP response-element binding (CREB)/brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway. Collectively, our findings could promote the prevalence of kucha as a common beverage with uses for health care and contribute to the development of theacrine as a potential novel antidepressant medicine.

Integrated analysis of multi-omics data on epigenetic changes caused by combined exposure to environmental hazards

Humans are easily exposed to environmentally hazardous factors in industrial sites or daily life. In addition, exposure to various substances and not just one harmful substance is common. However, research on the effects of combined exposure on humans is limited. Therefore, this study examined the effects of combined exposure to volatile organic compounds (VOCs) on the human body. We separated 193 participants into four groups according to their work-related exposure (nonexposure, toluene exposure, toluene and xylene exposure, and toluene, ethylbenzene, and xylene exposure). We then identified the methylation level and long noncoding RNA (lncRNA) levels by omics analyses, and performed an integrated analysis to examine the change of gene expression. Thereafter, the effects of combined exposure to environmental hazards on the human body were investigated and analyzed. Exposure to VOCs was found to negatively affect the development and maintenance of the nervous system. In particular, the MALAT1 lncRNA was found to be significantly reduced in the complex exposure group, and eight genes were significantly downregulated by DNA hypermethylation. The downregulation of these genes could cause a possible decrease in the density of synapses as well as the number and density of dendrites and spines. In summary, we found that increased combined exposure to environmental hazards could lead to additional epigenetic changes, and consequently abnormal dendrites, spines, and synapses, which could damage motor learning or spatial memory. Thus, lncRNA MALAT1 or FMR1 could be novel biomarkers of neurotoxicity to identify the negative health effects of VOC complex exposure.

Type IIa RPTPs and Glycans: Roles in Axon Regeneration and Synaptogenesis

Type IIa receptor tyrosine phosphatases (RPTPs) play pivotal roles in neuronal network formation. It is emerging that the interactions of RPTPs with glycans, i.e., chondroitin sulfate (CS) and heparan sulfate (HS), are critical for their functions. We highlight here the significance of these interactions in axon regeneration and synaptogenesis. For example, PTPσ, a member of type IIa RPTPs, on axon terminals is monomerized and activated by the extracellular CS deposited in neural injuries, dephosphorylates cortactin, disrupts autophagy flux, and consequently inhibits axon regeneration. In contrast, HS induces PTPσ oligomerization, suppresses PTPσ phosphatase activity, and promotes axon regeneration. PTPσ also serves as an organizer of excitatory synapses. PTPσ and neurexin bind one another on presynapses and further bind to postsynaptic leucine-rich repeat transmembrane protein 4 (LRRTM4). Neurexin is now known as a heparan sulfate proteoglycan (HSPG), and its HS is essential for the binding between these three molecules. Another HSPG, glypican 4, binds to presynaptic PTPσ and postsynaptic LRRTM4 in an HS-dependent manner. Type IIa RPTPs are also involved in the formation of excitatory and inhibitory synapses by heterophilic binding to a variety of postsynaptic partners. We also discuss the important issue of possible mechanisms coordinating axon extension and synapse formation.

Proper synaptic adhesion signaling in the control of neural circuit architecture and brain function

Trans-synaptic cell-adhesion molecules are critical for governing various stages of synapse development and specifying neural circuit properties via the formation of multifarious signaling pathways. Recent studies have pinpointed the putative roles of trans-synaptic cell-adhesion molecules in mediating various cognitive functions. Here, we review the literature on the roles of a diverse group of central synaptic organizers, including neurexins (Nrxns), leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs), and their associated binding proteins, in regulating properties of specific type of synapses and neural circuits. In addition, we highlight the findings that aberrant synaptic adhesion signaling leads to alterations in the structures, transmission, and plasticity of specific synapses across diverse brain areas. These results seem to suggest that proper trans-synaptic signaling pathways by Nrxns, LAR-RPTPs, and their interacting network is likely to constitute central molecular complexes that form the basis for cognitive functions, and that these complexes are heterogeneously and complexly disrupted in many neuropsychiatric and neurodevelopmental disorders.

Roles of type IIa receptor protein tyrosine phosphatases as synaptic organizers

Neurons establish circuits for brain functions such as cognition, emotion, learning, and memory. Their connections are mediated by synapses, which are specialized cell-cell adhesions responsible for neuronal signal transmission. During neurodevelopment, synapse formation is triggered by interactions of cell adhesion molecules termed synaptic organizers or synapse organizers. Type IIa receptor protein tyrosine phosphatases (IIa RPTPs; also known as leukocyte common antigen-related receptor tyrosine phosphatases or LAR-RPTPs) play important roles in axon guidance and neurite extension, and also serve as presynaptic organizers. IIa RPTPs transsynaptically interact with multiple sets of postsynaptic organizers, mostly in a splicing-dependent fashion. Here, we review and update research progress on IIa RPTPs, particularly regarding their functional roles in vivo demonstrated using conditional knockout approach and structural insights into their extracellular and intracellular molecular interactions revealed by crystallography and other biophysical techniques. Future directions in the research field of IIa RPTPs are also discussed, including recent findings of the molecular assembly mechanism underlying the formation of synapse-specific nanostructures essential for synaptic functions.

Histone lysine methyltransferase SETDB1 as a novel target for central nervous system diseases

Epigenetic changes that regulate chromatin structure have a major impact in genome stabilization and maintenance of cellular homeostasis, been recently implicated in the pathophysiology of central nervous system (CNS). Aberrant expression and dysregulation of histone modification enzymes has been associated with the development of several CNS disorders, revealing these enzymes as putative targets for drug development and novel therapeutic approaches. SETDB1 is a histone lysine methyltransferase responsible for the di- and tri-methylation of histone 3 (H3) at lysine (K) 9 in euchromatic regions further promoting gene silencing through heterochromatin formation. By this way, SETDB1 has been shown to regulate gene expression and influence normal cellular homeostasis required for nervous system function while it is also implicated in the pathogenesis of CNS disorders. Among them, brain tumors, schizophrenia, Huntington's disease, autism spectrum disorders along with alcohol-induced fetal neurobehavioral deficits and Prader-Willi syndrome are representative examples, indicating the aberrant expression and function of SETDB1 as a common pathogenic factor. In this review, we focus on SETDB1-associated molecular mechanisms implicated in CNS physiology and disease while we further discuss current pharmacological approaches targeting SETDB1 enzymatic activity with beneficial effects.

Splice-dependent trans-synaptic PTPδ-IL1RAPL1 interaction regulates synapse formation and non-REM sleep

Alternative splicing regulates trans‐synaptic adhesions and synapse development, but supporting in vivo evidence is limited. PTPδ, a receptor tyrosine phosphatase adhering to multiple synaptic adhesion molecules, is associated with various neuropsychiatric disorders; however, its in vivo functions remain unclear. Here, we show that PTPδ is mainly present at excitatory presynaptic sites by endogenous PTPδ tagging. Global PTPδ deletion in mice leads to input‐specific decreases in excitatory synapse development and strength. This involves tyrosine dephosphorylation and synaptic loss of IL1RAPL1, a postsynaptic partner of PTPδ requiring the PTPδ‐meA splice insert for binding. Importantly, PTPδ‐mutant mice lacking the PTPδ‐meA insert, and thus lacking the PTPδ interaction with IL1RAPL1 but not other postsynaptic partners, recapitulate biochemical and synaptic phenotypes of global PTPδ‐mutant mice. Behaviorally, both global and meA‐specific PTPδ‐mutant mice display abnormal sleep behavior and non‐REM rhythms. Therefore, alternative splicing in PTPδ regulates excitatory synapse development and sleep by modulating a specific trans‐synaptic adhesion.

NGL-3 in the regulation of brain development, Akt/GSK3b signaling, long-term depression, and locomotive and cognitive behaviors

Netrin-G ligand-3 (NGL-3) is a postsynaptic adhesion molecule known to directly interact with the excitatory postsynaptic scaffolding protein postsynaptic density-95 (PSD-95) and trans-synaptically with leukocyte common antigen-related (LAR) family receptor tyrosine phosphatases to regulate presynaptic differentiation. Although NGL-3 has been implicated in the regulation of excitatory synapse development by in vitro studies, whether it regulates synapse development or function, or any other features of brain development and function, is not known. Here, we report that mice lacking NGL-3 (Ngl3^−/− mice) show markedly suppressed normal brain development and postnatal survival and growth. A change of the genetic background of mice from pure to hybrid minimized these developmental effects but modestly suppressed N-methyl-D-aspartate (NMDA) receptor (NMDAR)-mediated synaptic transmission in the hippocampus without affecting synapse development, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (AMPAR)-mediated basal transmission, and presynaptic release. Intriguingly, long-term depression (LTD) was near-completely abolished in Ngl3^−/− mice, and the Akt/glycogen synthase kinase 3β (GSK3β) signaling pathway, known to suppress LTD, was abnormally enhanced. In addition, pharmacological inhibition of Akt, but not activation of NMDARs, normalized the suppressed LTD in Ngl3^−/− mice, suggesting that Akt hyperactivity suppresses LTD. Ngl3^−/− mice displayed several behavioral abnormalities, including hyperactivity, anxiolytic-like behavior, impaired spatial memory, and enhanced seizure susceptibility. Among them, the hyperactivity was rapidly improved by pharmacological NMDAR activation. These results suggest that NGL-3 regulates brain development, Akt/GSK3β signaling, LTD, and locomotive and cognitive behaviors.

Activation of Agrp neurons modulates memory-related cognitive processes in mice

Hypothalamic Agrp neurons are critical regulators of food intake in adult mice. In addition to food intake, these neurons have been involved in other cognitive processes, such as the manifestation of stereotyped behaviors. Here, we evaluated the extent to which Agrp neurons modulate mouse behavior in spatial memory-related tasks. We found that activation of Agrp neurons did not affect spatial learning but altered behavioral flexibility using a modified version of the Barnes Maze task. Furthermore, using the Y-maze test to probe working memory, we found that chemogenetic activation of Agrp neurons reduced spontaneous alternation behavior mediated by the neuropeptide Y receptor-5 signaling. These findings suggest novel functional properties of Agrp neurons in memory-related cognitive processes.

Current Understanding of the Role of Neuronal Calcium Sensor 1 in Neurological Disorders

Neuronal calcium sensor 1 (NCS-1) is a high-affinity calcium-binding protein and its ubiquitous expression in the nervous system implies a wide range of functions. To date, it has been implicated in regulation of calcium channels in both axonal growth cones and presynaptic terminals, pre- and postsynaptic plasticity mechanisms, learning and memory behaviors, dopaminergic signaling, and axonal regeneration. This review summarizes these functions and relates them to several diseases in which NCS-1 plays a role, such as schizophrenia and bipolar disorder, X-linked mental retardation and fragile X syndrome, and spinal cord injury. Many questions remain unanswered about the role of NCS-1 in these diseases, particularly as the genetic factors that control NCS-1 expression in both normal and diseased states are still poorly understood. The review further identifies the therapeutic potential of manipulating the interaction of NCS-1 with its many targets and suggests directions for future research on the role of NCS-1 in these disorders.

Immunoglobulin-Like Receptors and Their Impact on Wiring of Brain Synapses

Synapse formation is mediated by a surprisingly large number and wide variety of genes encoding many different protein classes. One of the families increasingly implicated in synapse wiring is the immunoglobulin superfamily (IgSF). IgSF molecules are by definition any protein containing at least one Ig-like domain, making this family one of the most common protein classes encoded by the genome. Here, we review the emerging roles for IgSF molecules in synapse formation specifically in the vertebrate brain, focusing on examples from three classes of IgSF members: ( a) cell adhesion molecules, ( b) signaling molecules, and ( c) immune molecules expressed in the brain. The critical roles for IgSF members in regulating synapse formation may explain their extensive involvement in neuropsychiatric and neurodevelopmental disorders. Solving the IgSF code for synapse formation may reveal multiple new targets for rescuing IgSF-mediated deficits in synapse formation and, eventually, new treatments for psychiatric disorders caused by altered IgSF-induced synapse wiring.

The Communication Between the Immune and Nervous Systems: The Role of IL-1β in Synaptopathies

In the last 15 years, groundbreaking genetic progress has underlined a convergence onto coherent synaptic pathways for most psychiatric and neurodevelopmental disorders, which are now collectively called “synaptopathies.” However, the modest size of inheritance detected so far indicates a multifactorial etiology for these disorders, underlining the key contribution of environmental effects to them. Inflammation is known to influence the risk and/or severity of a variety of synaptopathies. In particular, pro-inflammatory cytokines, produced and released in the brain by activated astrocytes and microglia, may play a pivotal role in these pathologies. Although the link between immune system activation and defects in cognitive processes is nowadays clearly established, the knowledge of the molecular mechanisms by which inflammatory mediators specifically hit synaptic components implicated in synaptopathies is still in its infancy. This review summarizes recent evidence showing that the pro-inflammatory cytokine interleukin-1β (IL-1β) specifically targets synaptopathy molecular substrate, leading to memory defects and pathological processes. In particular, we describe three specific pathways through which IL-1β affects (1) synaptic maintenance/dendritic complexity, (2) spine morphology, and (3) the excitatory/inhibitory balance. We coin the term immune synaptopathies to identify this class of diseases.

The enigmatic role of IL-38 in inflammatory diseases

IL-38 is the most recently discovered cytokine of the IL-1 family and is considered a potential inhibitor of the IL-1 and Toll-like receptor families. IL-38 exerts anti-inflammatory properties, especially on macrophages, by inhibiting secretion of pro-inflammatory cytokines, leading to reduced T-lymphocyte TH17 maturation. IL-38 has been studied most extensively in the context of chronic inflammatory diseases, particularly arthritis, where it is considered an attractive new drug candidate. IL-38 research has entered a new phase, with the realization that IL-38 is important in the pathophysiology of TH17 dependent-diseases (psoriasis, psoriatic arthritis and ankylosing spondylitis). In this review, we provide a critical evaluation of several controversial issues concerning IL-38 function and regulation. There is effectively contrasting data regarding IL-38: it is produced in conditions such as apoptosis, necrosis or inflammation, but data is lacking regarding IL-38 processing and biological function. Furthermore, the receptor for IL-38 has yet to be identified, although three candidate receptors - IL-1R1, IL-36R and IL-1RAPL1-have been proposed. Future studies will hopefully uncover new aspects of this enigmatic cytokine.

Research of differential expression of sIL1RAP in low-grade gliomas between children and adults

Glioma is the most common intracranial malignant tumor. Low-grade gliomas (LGG) occupy almost 80% in all of the gliomas. The prognosis of LGG in children is much better than in adult, however, the molecular mechanism is still unclear. In our investigation, it was first found that the level of soluble IL1RAP (sIL1RAP) was significantly higher in the LGG from children than that from adult. We also revealed that sIL1RAP could induce the apoptosis of U251. In cells with overexpression of sIL-1RAP, the cell proliferation promoted by IL-1 was significantly inhibited. These decreased tumor growth ability and better prognosis of low-grade gliomas in children patients than that in adult patients. The expression level of sIL1RAP may become one of the potential indexes for determining the prognosis of low-grade gliomas.

Comprehensive Behavioral Analysis of Activating Transcription Factor 5-Deficient Mice

Activating transcription factor 5 (ATF5) is a member of the CREB/ATF family of basic leucine zipper transcription factors. We previously reported that ATF5-deficient (ATF5^-/-) mice demonstrated abnormal olfactory bulb development due to impaired interneuron supply. Furthermore, ATF5^-/- mice were less aggressive than ATF5^+/+ mice. Although ATF5 is widely expressed in the brain, and involved in the regulation of proliferation and development of neurons, the physiological role of ATF5 in the higher brain remains unknown. Our objective was to investigate the physiological role of ATF5 in the higher brain. We performed a comprehensive behavioral analysis using ATF5^-/- mice and wild type littermates. ATF5^-/- mice exhibited abnormal locomotor activity in the open field test. They also exhibited abnormal anxiety-like behavior in the light/dark transition test and open field test. Furthermore, ATF5^-/- mice displayed reduced social interaction in the Crawley’s social interaction test and increased pain sensitivity in the hot plate test compared with wild type. Finally, behavioral flexibility was reduced in the T-maze test in ATF5^-/- mice compared with wild type. In addition, we demonstrated that ATF5^-/- mice display disturbances of monoamine neurotransmitter levels in several brain regions. These results indicate that ATF5 deficiency elicits abnormal behaviors and the disturbance of monoamine neurotransmitter levels in the brain. The behavioral abnormalities of ATF5^-/- mice may be due to the disturbance of monoamine levels. Taken together, these findings suggest that ATF5^-/- mice may be a unique animal model of some psychiatric disorders.

The X-Linked Intellectual Disability Protein IL1RAPL1 Regulates Dendrite Complexity

Mutations and deletions of the interleukin-1 receptor accessory protein like 1 (IL1RAPL1) gene, located on the X chromosome, are associated with intellectual disability (ID) and autism spectrum disorder (ASD). IL1RAPL1 protein is located at the postsynaptic compartment of excitatory synapses and plays a role in synapse formation and stabilization. Here, using primary neuronal cultures and Il1rapl1-KO mice, we characterized the role of IL1RAPL1 in regulating dendrite morphology. In Il1rapl1-KO mice we identified an increased number of dendrite branching points in CA1 and CA2 hippocampal neurons associated to hippocampal cognitive impairment. Similarly, induced pluripotent stem cell-derived neurons from a patient carrying a null mutation of the IL1RAPL1 gene had more dendrites. In hippocampal neurons, the overexpression of full-length IL1RAPL1 and mutants lacking part of C-terminal domains leads to simplified neuronal arborization. This effect is abolished when we overexpressed mutants lacking part of N-terminal domains, indicating that the IL1RAPL1 extracellular domain is required for regulating dendrite development. We also demonstrate that PTPδ interaction is not required for this activity, while IL1RAPL1 mediates the activity of IL-1β on dendrite morphology. Our data reveal a novel specific function for IL1RAPL1 in regulating dendrite morphology that can help clarify how changes in IL1RAPL1-regulated pathways can lead to cognitive disorders in humans.SIGNIFICANCE STATEMENT Abnormalities in the architecture of dendrites have been observed in a variety of neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. Here we show that the X-linked intellectual disability protein interleukin-1 receptor accessory protein like 1 (IL1RAPL1) regulates dendrite morphology of mice hippocampal neurons and induced pluripotent stem cell-derived neurons from a patient carrying a null mutation of IL1RAPL1 gene. We also found that the extracellular domain of IL1RAPL1 is required for this effect, independently of the interaction with PTPδ, but IL1RAPL1 mediates the activity of IL-1β on dendrite morphology. Our data reveal a novel specific function for IL1RAPL1 in regulating dendrite morphology that can help clarify how changes in IL1RAPL1-regulated pathways can lead to cognitive disorders in humans.

The axon degeneration gene SARM1 is evolutionarily distinct from other TIR domain-containing proteins

Many forms of neurodegenerative disease are characterized by Wallerian degeneration, an active program of axonal destruction. Recently, the important player which enacts Wallerian degeneration was discovered, the multidomain protein SARM1. Since the SARM1 protein has classically been thought of as an innate immune molecule, its role in Wallerian degeneration has raised questions on the evolutionary forces acting on it. Here, we synthesize a picture of SARM1's evolution through various organisms by examining the molecular and genetic changes of SARM1 and the genes around it. Using proteins that possess domains homologous to SARM1, we established distances and Ka/Ks values through 5671 pairwise species-species comparisons. We demonstrate that SARM1 diverged across species in a pattern similar to other SAM domain-containing proteins. This is surprising, because it was expected that SARM1 would behave more like its TIR domain relatives. Going along with this divorce from TIR, we also noted that SARM1's TIR is under stronger purifying selection than the rest of the TIR domain-containing proteins (remaining highly conserved). In addition, SARM1's synteny analysis reveals that the surrounding gene cluster is highly conserved, functioning as a potential nexus of gene functionality across species. Taken together, SARM1 demonstrates a unique evolutionary pattern, separate from the TIR domain protein family.

α4βδ GABAA receptors reduce dendritic spine density in CA1 hippocampus and impair relearning ability of adolescent female mice: Effects of a GABA agonist and a stress steroid

Synaptic pruning underlies the transition from an immature to an adult CNS through refinements of neuronal circuits. Our recent study indicates that pubertal synaptic pruning is triggered by the inhibition generated by extrasynaptic α4βδ GABA_A receptors (GABARs) which are increased for 10 d on dendritic spines of CA1 pyramidal cells at the onset of puberty (PND 35-44) in the female mouse, suggesting α4βδ GABARs as a novel target for the regulation of adolescent synaptic pruning. In the present study we used a pharmacological approach to further examine the role of these receptors in altering spine density during puberty of female mice and the impact of these changes on spatial learning, assessed in adulthood. Two drugs were chronically administered during the pubertal period (PND 35-44): the GABA agonist gaboxadol (GBX, 0.1mg/kg, i.p.), to enhance current gated by α4βδ GABARs and the neurosteroid/stress steroid THP (3α-OH-5β-pregnan-20-one, 10mg/kg, i.p.) to decrease expression of α4βδ. Spine density was determined on PND 56 with Golgi staining. Spatial learning and relearning were assessed using the multiple object relocation task and an active place avoidance task on PND 56. Pubertal GBX decreased spine density post-pubertally by 70% (P<0.05), while decreasing α4βδ expression with THP increased spine density by twofold (P<0.05), in both cases, with greatest effects on the mushroom spines. Adult relearning ability was compromised in both hippocampus-dependent tasks after pubertal administration of either drug. These findings suggest that an optimal spine density produced by α4βδ GABARs is necessary for optimal cognition in adults.

AIM 2 inflammasomes regulate neuronal morphology and influence anxiety and memory in mice

Inflammasomes are the protein assemblies that consist of inflammasome sensors, adaptor apoptosis-associated speck-like proteins containing a CARD (ASC) and inflammasome caspase. Inflammasomes sense multiple danger signals via various inflammasome sensors and consequently use caspase to trigger proteolytic processing and secretion of IL-1β cytokines. Recent studies have suggested that neurons use their own innate immune system to detect danger signals and regulate neuronal morphology. Here, we investigate whether inflammasomes, the critical components of innate immunity, participate in regulation of neuronal morphology and function. Among various sensors, Absent in melanoma 2 (Aim2) expression in neurons is most prominent. Adding synthetic double-stranded DNA (dsDNA) to cultured neurons induces IL-1β secretion in an AIM2-dependent manner and consequently downregulates dendritic growth but enhances axon extension. The results of Aim2 knockout and knockdown show that AIM2 acts cell-autonomously to regulate neuronal morphology. Behavioral analyses further reveal that Aim2-/- mice exhibit lower locomotor activity, increased anxious behaviors and reduced auditory fear memory. In conclusion, our study suggests that AIM2 inflammasomes regulate neuronal morphology and influence mouse behaviors.

Microglia contact induces synapse formation in developing somatosensory cortex

Microglia are the immune cells of the central nervous system that play important roles in brain pathologies. Microglia also help shape neuronal circuits during development, via phagocytosing weak synapses and regulating neurogenesis. Using in vivo multiphoton imaging of layer 2/3 pyramidal neurons in the developing somatosensory cortex, we demonstrate here that microglial contact with dendrites directly induces filopodia formation. This filopodia formation occurs only around postnatal day 8-10, a period of intense synaptogenesis and when microglia have an activated phenotype. Filopodia formation is preceded by contact-induced Ca(2+) transients and actin accumulation. Inhibition of microglia by genetic ablation decreases subsequent spine density, functional excitatory synapses and reduces the relative connectivity from layer 4 neurons. Our data provide the direct demonstration of microglial-induced spine formation and provide further insights into immune system regulation of neuronal circuit development, with potential implications for developmental disorders of immune and brain dysfunction.

Preliminary assessment of pre-morbid DNA methylation in individuals at high genetic risk of mood disorders

OBJECTIVES

Accumulating evidence implicates altered DNA methylation in psychiatric disorders, including bipolar disorder (BD) and major depressive disorder (MDD). It is not clear, however, whether these changes are causative or result from illness progression or treatment. To disentangle these possibilities we profiled genome-wide DNA methylation in well, unrelated individuals at high familial risk of mood disorder. DNA methylation was compared between individuals who subsequently developed BD or MDD [ill later (IL)] and those who remained well [well later (WL)].

METHODS

DNA methylation profiles were obtained from whole-blood samples from 22 IL and 23 WL individuals using the Infinium HumanMethylation450 BeadChip. Differential methylation was assessed on a single-locus and regional basis. Pathway analysis was performed to assess enrichment for particular biological processes amongst nominally significantly differentially methylated loci.

RESULTS

Although no locus withstood correction for multiple testing, uncorrected P-values provided suggestive evidence for altered methylation at sites within genes previously implicated in neuropsychiatric conditions, such as Transcription Factor 4 (TCF4) and Interleukin 1 Receptor Accessory Protein-Like 1 ([IL1RAPL1]; P≤3.11×10(-5) ). Pathway analysis revealed significant enrichment for several neurologically relevant pathways and functions, including Nervous System Development and Function and Behavior; these findings withstood multiple testing correction (q≤0.05). Analysis of differentially methylated regions identified several within the major histocompatibility complex (P≤.000 479), a region previously implicated in schizophrenia and BD.

CONCLUSIONS

Our data provide provisional evidence for the involvement of altered whole-blood DNA methylation in neurologically relevant genes in the aetiology of mood disorders. These findings are convergent with the findings of genome-wide association studies.

Puzzling out presynaptic differentiation

Proper brain function in the nervous system relies on the accurate establishment of synaptic contacts during development. Countless synapses populate the adult brain in an orderly fashion. In each synapse, a presynaptic terminal loaded with neurotransmitters-containing synaptic vesicles is perfectly aligned to an array of receptors in the postsynaptic membrane. Presynaptic differentiation, which encompasses the events underlying assembly of new presynaptic units, has seen notable advances in recent years. It is now consensual that as a growing axon encounters the receptive dendrites of its partner, presynaptic assembly will be triggered and specified by multiple postsynaptically-derived factors including soluble molecules and cell adhesion complexes. Presynaptic material that reaches these distant sites by axonal transport in the form of pre-assembled packets will be retained and clustered, ultimately giving rise to a presynaptic bouton. This review focuses on the cellular and molecular aspects of presynaptic differentiation in the central nervous system, with a particular emphasis on the identity of the instructive factors and the intracellular processes used by neuronal cells to assemble functional presynaptic terminals. We provide a detailed description of the mechanisms leading to the formation of new presynaptic terminals. In brief, soma-derived packets of pre-assembled material are trafficked to distant axonal sites. Synaptogenic factors from dendritic or glial provenance activate downstream intra-axonal mediators to trigger clustering of passing material and their correct organization into a new presynaptic bouton. This article is part of a mini review series: "Synaptic Function and Dysfunction in Brain Diseases".

Emergent Synapse Organizers: LAR-RPTPs and Their Companions

Leukocyte common antigen-related receptor tyrosine phosphatases (LAR-RPTPs) have emerged as key players that organize various aspects of neuronal development, including axon guidance, neurite extension, and synapse formation and function. Recent research has highlighted the roles of LAR-RPTPs at neuronal synapses in mediating distinct synaptic adhesion pathways through interactions with a host of extracellular ligands and in governing a variety of intracellular signaling cascades through binding to various scaffolds and signaling proteins. In this chapter, we review and update current research progress on the extracellular ligands of LAR-RPTPs, regulation of their extracellular interactions by alternative splicing and heparan sulfates, and their intracellular signaling machineries. In particular, we review structural insights on complexes of LAR-RPTPs with their various ligands. These studies lend support to general molecular mechanisms underlying LAR-RPTP-mediated synaptic adhesion and signaling pathways.

Anxiolytic-like effect of hydroalcoholic extract of ripe pistachio hulls in adult female Wistar rats and its possible mechanisms

The present study was designed to study the preventive effect of hydroalcoholic extract of ripe pistachio hulls (RPH) in the elevated plus maze model of anxiety. One hundred twenty female wistar rats in their estrous cycle were divided into 15 groups of 8 each and received various concentrations of hydroalcoholic extract of RPH except the control groups. Elevated plus maze was used to measure the level of anxiety. Percentage of time spent in the open arms (%OAT), percentage of the number of entries into the open arms (%OAE), locomotor activity, and time spent in the closed arms (CAT), and the number of entries in to the closed arms (CAE) were measured and compared. Dose-response experiments showed that only 10 mg/kg dose of RPH extract significantly increased %OAT (P < 0.001) and %OAE (P < 0.05) compared to the control group, indicating anti-anxiety effects of the extract. Also, pentylenetetrazol and an estrogen receptor antagonist (ERA) tamoxifen could block anti-anxiety effects of the extract (P < 0.001). It was also noticed that tamoxifen was able to significantly reduce locomotor activity. As the RPH extract showed a preventive effect in experimental model of anxiety, it might be concomitantly administered with other anxiolytic medications.

Liver X Receptor Agonist Modifies the DNA Methylation Profile of Synapse and Neurogenesis-Related Genes in the Triple Transgenic Mouse Model of Alzheimer's Disease

The liver X receptor agonist, GW3965, improves cognition in Alzheimer's disease (AD) mouse models. Here, we determined if short-term GW3965 treatment induces changes in the DNA methylation state of the hippocampus, which are associated with cognitive improvement. Twenty-four-month-old triple-transgenic AD (3xTg-AD) mice were treated with GW3965 (50 mg/kg/day for 6 days). DNA methylation state was examined by modified bisulfite conversion and hybridization on Illumina Infinium Methylation BeadChip 450 k arrays. The Morris water maze was used for behavioral analysis. Our results show in addition to improvement in cognition methylation changes in 39 of 13,715 interrogated probes in treated 3xTg-AD mice compared with untreated 3xTg-AD mice. These changes in methylation probes include 29 gene loci. Importantly, changes in methylation status were mainly from synapse-related genes (SYP, SYN1, and DLG3) and neurogenesis-associated genes (HMGB3 and RBBP7). Thus, our results indicate that liver X receptors (LXR) agonist treatment induces rapid changes in DNA methylation, particularly in loci associated with genes involved in neurogenesis and synaptic function. Our results suggest a new potential mechanism to explain the beneficial effect of GW3965.

Glutamate synapses in human cognitive disorders

Accumulating data, including those from large genetic association studies, indicate that alterations in glutamatergic synapse structure and function represent a common underlying pathology in many symptomatically distinct cognitive disorders. In this review, we discuss evidence from human genetic studies and data from animal models supporting a role for aberrant glutamatergic synapse function in the etiology of intellectual disability (ID), autism spectrum disorder (ASD), and schizophrenia (SCZ), neurodevelopmental disorders that comprise a significant proportion of human cognitive disease and exact a substantial financial and social burden. The varied manifestations of impaired perceptual processing, executive function, social interaction, communication, and/or intellectual ability in ID, ASD, and SCZ appear to emerge from altered neural microstructure, function, and/or wiring rather than gross changes in neuron number or morphology. Here, we review evidence that these disorders may share a common underlying neuropathy: altered excitatory synapse function. We focus on the most promising candidate genes affecting glutamatergic synapse function, highlighting the likely disease-relevant functional consequences of each. We first present a brief overview of glutamatergic synapses and then explore the genetic and phenotypic evidence for altered glutamate signaling in ID, ASD, and SCZ.