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The BTBR T+Itpr3tf/J (BTBR/J) strain is one of the most valid models of idiopathic autism, serving as a potent forward genetics tool to dissect the complexity of autism. We found that a sister strain with an intact corpus callosum, BTBR TF/ArtRbrc (BTBR/R), showed more prominent autism core symptoms but moderate ultrasonic communication/normal hippocampus-dependent memory, which may mimic autism in the high functioning spectrum. Intriguingly, disturbed epigenetic silencing mechanism leads to hyperactive endogenous retrovirus (ERV), a mobile genetic element of ancient retroviral infection, which increases de novo copy number variation (CNV) formation in the two BTBR strains. This feature makes the BTBR strain a still evolving multiple-loci model toward higher ASD susceptibility. Furthermore, active ERV, analogous to virus infection, evades the integrated stress response (ISR) of host defense and hijacks the transcriptional machinery during embryonic development in the BTBR strains. These results suggest dual roles of ERV in the pathogenesis of ASD, driving host genome evolution at a long-term scale and managing cellular pathways in response to viral infection, which has immediate effects on embryonic development. The wild-type Draxin expression in BTBR/R also makes this substrain a more precise model to investigate the core etiology of autism without the interference of impaired forebrain bundles as in BTBR/J.

Maternally inherited duplication of chromosome 15q11-q13 (Dup15q) is a pathogenic copy number variation (CNV) associated with autism spectrum disorder (ASD). Recently, paternally derived duplication has also been shown to contribute to the development of ASD. The molecular mechanism underlying paternal Dup15q remains unclear. Here, we conduct genetic and overexpression-based screening and identify Necdin (Ndn) as a driver gene for paternal Dup15q resulting in the development of ASD-like phenotypes in mice. An excess amount of Ndn results in enhanced spine formation and density as well as hyperexcitability of cortical pyramidal neurons. We generate 15q dupΔNdn mice with a normalized copy number of Ndn by excising its one copy from Dup15q mice using a CRISPR-Cas9 system. 15q dupΔNdn mice do not show ASD-like phenotypes and show dendritic spine dynamics and cortical excitatory-inhibitory balance similar to wild type animals. Our study provides an insight into the role of Ndn in paternal 15q duplication and a mouse model of paternal Dup15q syndrome., Duplication of chromosome 15q11-q13 is associated with autism spectrum disorder (ASD). Here, the authors show that in mice paternal Dup15q results in ASD-like neuronal and behavioural impairment driven by Necdin.

UBE3A is a gene responsible for the pathogenesis of Angelman syndrome (AS), a neurodevelopmental disorder characterized by symptoms such as intellectual disability, delayed development and severe speech impairment. UBE3A encodes an E3 ubiquitin ligase, for which several targets have been identified, including synaptic molecules. Although proteolysis mainly occurs in the cytoplasm, UBE3A is localized to the cytoplasm and the nucleus. In fact, UBE3A is also known as a transcriptional regulator of the family of nuclear receptors. However, the function of UBE3A in the nucleus remains unclear. Therefore, we examined the involvement of UBE3A in transcription in the nuclei of neurons. Genome-wide transcriptome analysis revealed an enrichment of genes downstream of interferon regulatory factor (IRF) in a UBE3A-deficient AS mouse model. In vitro biochemical analyses further demonstrated that UBE3A interacted with IRF and, more importantly, that UBE3A enhanced IRF-dependent transcription. These results suggest a function for UBE3A as a transcriptional regulator of the immune system in the brain. These findings also provide informative molecular insights into the function of UBE3A in the brain and in AS pathogenesis.

Studying the animal models of human neuropsychiatric disorders can facilitate the understanding of mechanisms of symptoms both physiologically and genetically. Previous studies have shown that ultrasonic vocalisations (USVs) of mice might be efficient markers to distinguish the wild type group and the model of autism spectrum disorder (mASD). Nevertheless, in-depth analysis of these 'silence' sounds by leveraging the power of advanced computer audition technologies (e. g., deep learning) is limited. To this end, we propose a pilot study on using a large-scale pre-trained audio neural network to extract high-level representations from the USVs of mice for the task on detection of mASD. Experiments have shown a best result reaching an unweighted average recall of 79.2 % for the binary classification task in a rigorous subject-independent scenario. To the best of our knowledge, this is the first time to analyse the sounds that cannot be heard by human beings for the detection of mASD mice. The novel findings can be significant to motivate future works with according means on studying animal models of human patients.

MRI is a promising tool for translational research to link brain function and structure in animal models of disease to patients with neuropsychiatric disorders. However, given that mouse functional MRI (fMRI) typically relies on anesthetics to suppress head motion and physiological noise, it has been difficult to directly compare brain fMRI in anesthetized mice with that in conscious patients. Here, we developed a new system to acquire fMRI in awake mice, which includes a head positioner and dedicated radio frequency coil. The system was used to investigate functional brain networks in conscious mice, with the goal of enabling future studies to bridge fMRI of disease model animals with human fMRI. Cranioplastic surgery was performed to affix the head mount and the cupped-hand handling method was performed to minimize stress during MRI scanning. Here we describe the new mouse fMRI system, cranioplastic surgery and acclimation protocol. Graphic abstract: [Image: see text] Awake fMRI system to investigate the neuronal activity in awaked mice.

It is well established that serotonergic fibers distribute throughout the brain. Abnormal densities or patterns of serotonergic fibers have been implicated in neuropsychiatric disorders. Although many classical studies have examined the distribution pattern of serotonergic fibers, most of them were either limited to specific brain areas or had limitations in demonstrating the fine axonal morphology. In this study, we utilize male mice expressing green fluorescence protein under the serotonin transporter (SERT) promoter to map the topography of serotonergic fibers across the rostro-caudal extent of each brain area. We demonstrate previously unreported regional density and fine-grained anatomy of serotonergic fibers. Our findings include: (a) SERT fibers distribute abundantly in the thalamic nuclei close to the midline and dorsolateral areas, in most of the hypothalamic nuclei with few exceptions such as the median eminence and arcuate nuclei, and within the basal amygdaloid complex and lateral septal nuclei, (b) the source fibers of innervation of the hippocampus traverse through the septal nuclei before reaching its destination, (c) unique, filamentous type of straight terminal fibers within the nucleus accumbens, (d) laminar pattern of innervation in the hippocampus, olfactory bulb and cortex with heterogenicity in innervation density among the layers, (e) cortical labeling density gradually decreases rostro-caudally, (f) fibers traverse and distribute mostly within the gray matter, leaving the white fiber bundles uninnervated, and (g) most of the highly labeled nuclei and cortical areas have predominant anatomical connection to limbic structures. In conclusion, we provide novel, regionally specific insights on the distribution map of serotonergic fibers using transgenic mouse.

It is well established that serotonergic fibers distribute throughout the brain. Abnormal densities or patterns of serotonergic fibers have been implicated in neuropsychiatric disorders. Although many classical studies have examined the distribution pattern of serotonergic fibers, most of them were either limited to specific brain areas or had limitations in demonstrating the fine axonal morphology. In this study, we utilize transgenic mice expressing GFP under the SERT promoter to map the topography of serotonergic fibers across the rostro-caudal extent of each brain area. We demonstrate previously unreported regional density and fine-grained anatomy of serotonergic fibers. Our findings include: 1) SERT fibers distribute abundantly in the thalamic nuclei close to the midline and dorsolateral areas, in most of the hypothalamic nuclei with few exceptions such as the median eminence and arcuate nuclei, and within the basal amygdaloid complex and lateral septal nuclei, 2) the source fibers of innervation of the hippocampus traverse through the septal nuclei before reaching its destination, 3) unique, filamentous type of straight terminal fibers within the nucleus accumbens, 4) laminar pattern of innervation in the hippocampus, olfactory bulb and cortex with heterogenicity in innervation density among the layers, 5) cortical labelling density gradually decreases rostro-caudally, 6) fibers traverse and distribute mostly within the gray matter, leaving the white fiber bundles uninnervated, and 7) most of the highly labelled nuclei and cortical areas have predominant anatomical connection to limbic structures. In conclusion, we provide novel, regionally specific insights on the distribution map of serotonergic fibers using transgenic mouse.

During embryonic development, GABAergic interneurons, a main inhibitory component in the cerebral cortex, migrate tangentially from the ganglionic eminence (GE) to cerebral cortex. After reaching the cerebral cortex, they start to extend their neurites for constructing local neuronal circuits around the neonatal stage. Aberrations in migration or neurite outgrowth are implicated in neurological and psychiatric disorders such as epilepsy, schizophrenia and autism. Previous studies revealed that in the early phase of cortical development the neural population migrates tangentially from the GE in the telencephalon and several genes have been characterized as regulators of migration and specification of GABAergic interneurons. However, much less is known about the molecular mechanisms of GABAergic interneurons-specific maturation at later stages of development. Here, we performed genome-wide screening to identify genes related to the later stage by flow cytometry based-microarray (FACS-array) and identified 247 genes expressed in cortical GABAergic interneurons. Among them, Dgkg, a member of diacylglycerol kinase family, was further analyzed. Correlational analysis revealed that Dgkg is dominantly expressed in somatostatin (SST)-expressing GABAergic interneurons. The functional study of Dgkg using GE neurons indicated alteration in neurite outgrowth of GABAergic neurons. This study shows a new functional role for Dgkg in GABAergic interneurons as well as the identification of other candidate genes for their maturation.

Autism spectrum disorder (ASD) is a complex and heterogeneous neurodevelopmental disorder. In addition to the core symptoms of ASD, many patients with ASD also show comorbid gut dysbiosis, which may lead to various gastrointestinal (GI) problems. Intriguingly, there is evidence that gut microbiota communicate with the central nervous system to modulate behavioral output through the gut-brain axis. To investigate how the microbiota composition is changed in ASD and to identify which microbes are involved in autistic behaviors, we performed a 16S rRNA gene-based metagenomics analysis in an ASD mouse model. Here, we focused on a model with human 15q11-13 duplication (15q dup), the most frequent chromosomal aberration or copy number variation found in ASD. Species diversity of the microbiome was significantly decreased in 15q dup mice. A combination of antibiotics treatment and behavioral analysis showed that neomycin improved social communication in 15q dup mice. Furthermore, comparison of the microbiota composition of mice treated with different antibiotics enabled us to identify beneficial operational taxonomic units (OTUs) for ultrasonic vocalization.

Copy number variants (CNVs), characterized in recent years by cutting-edge technology, add complexity to our knowledge of the human genome. CNVs contribute not only to human diversity but also to different kinds of diseases including neurodevelopmental delay, autism spectrum disorder and neuropsychiatric diseases. Interestingly, many pathogenic CNVs are shared among these diseases. Studies suggest that pathophysiology of disease may not be simply attributed to a single driver gene within a CNV but also that multifactorial effects may be important. Gene expression and the resulting phenotypes may also be affected by epigenetic alteration and chromosomal structural changes. Combined with human genetics and systems biology, integrative research by multi-dimensional approaches using animal and cell models of CNVs are expected to further understanding of pathophysiological mechanisms of neurodevelopmental disorders and neuropsychiatric disorders.

International audience; Duplications of human chromosome 2q13 have been reported in patients with neurodevelopmental disorder including autism spectrum disorder. Nephronophthisis-1 (NPHP1) was identified as a causative gene in the minimal deletion on chromosome 2q13 for familial juvenile type 1 nephronophthisis and Joubert syndrome, an autosomal recessive neurodevelopmental disorder characterized by a cerebellar and brain stem malformation, hypotonia, developmental delay, ataxia, and sometimes associated with cognitive impairment. NPHP1 encodes a ciliary protein, nephrocystin-1, which is expressed in the brain, yet its function in the brain remains largely unknown. In this study, we generated bacterial artificial chromosome-based transgenic mice, called 2q13 dup, that recapitulate human chromosome 2q13 duplication and contain one extra copy of the Nphp1 transgene. To analyze any behavioral alterations in 2q13 dup mice, we conducted a battery of behavioral tests. Although 2q13 dup mice show no significant differences in social behavior, they show deficits in spontaneous alternation behavior and fear memory. We also carried out magnetic resonance imaging to confirm whether copy number gain in this locus affects the neuroanatomy. There was a trend toward a decrease in the cerebellar paraflocculus of 2q13 dup mice. This is the first report of a genetic mouse model for human 2q13 duplication.

This article contains data related to the research article entitled “Id2 determines intestinal identity through repression of the foregut transcription factor, Irx5” [1]. Id2 deficient (Id2−/−) mice developed gastric tumors and heterotopic squamous epithelium in the small intestine. These tumors and heterotopic tissues were derived from ectopic gastric cells and squamous cells formed in the small intestine respectively during development. In this study, microarray data of the developing small intestine of Id2−/− mice was analyzed. Keywords: Endoderm, Foregut, Midgut, Id2, Sox21, Microarray

This article contains data related to the research article entitled “Id2 determines intestinal identity through repression of the foregut transcription factor, Irx5” [1]. Id2 deficient (Id2−/−) mice developed gastric tumors and heterotopic squamous epithelium in the small intestine. These tumors and heterotopic tissues were derived from ectopic gastric cells and squamous cells formed in the small intestine respectively during development. In this study, microarray data of the developing small intestine of Id2−/− mice was analyzed.

Serotonin (5-HT) and its innervation have been implicated in various neural functions including circadian systems. Although classical studies have examined the 5-HT innervation pattern in the adult suprachiasmatic nucleus (SCN), the fine-grained morphological study of the development of pathway and terminal projections to the SCN remains scarce. Here, we utilize transgenic mice expressing GFP under the serotonin transporter (SERT) promoter to subserve our developmental mapping study. We demonstrate that the morphology of 5-HT pathway fibers decussating over the supraoptic commissure that projects to the SCN exhibits two distinct developmental patterns. The punctate fibers at the fetal stage gradually become smooth and filamentous, especially during postnatal one week and remain constant thereafter. The innervation field in the SCN develops properly only during postnatal two weeks. Its ventromedial area remains one of the highest 5-HT innervated areas in the adult brain, whereas the dorsolateral area is less innervated. Thus, we provide novel and specific insights on the developmental map of 5-HT system into the SCN using transgenic mouse.

Awake fMRI detects the hypoconnectivity partially rescued by d-cycloserine treatment in 15q dup mice., MRI has potential as a translational approach from rodents to humans. However, given that mouse functional MRI (fMRI) uses anesthetics for suppression of motion, it has been difficult to directly compare the result of fMRI in “unconsciousness” disease model mice with that in “consciousness” patients. We develop awake fMRI to investigate brain function in 15q dup mice, a copy number variation model of autism. Compared to wild-type mice, we find that 15q dup is associated with whole-brain functional hypoconnectivity and diminished fMRI responses to odors of stranger mice. Ex vivo diffusion MRI reveals widespread anomalies in white matter ultrastructure in 15q dup mice, suggesting a putative anatomical substrate for these functional hypoconnectivity. We show that d-cycloserine (DCS) treatment partially normalizes these anormalies in the frontal cortex of 15q dup mice and rescues some social behaviors. Our results demonstrate the utility of awake rodent fMRI and provide a rationale for further investigation of DCS therapy.

Grb2-associated regulator of Erk/MAPK (GAREM), is an adaptor protein related to the several cell growth factor receptor-signaling. The GAREM family has two subtypes, GAREM1 and GAREM2, both encoded in the human and mouse genome. Recent genome-wide research identified GAREM2 as a candidate of neurodegenerative diseases. Here, we use knockout (KO) mice to show the role of GAREM2, that is highly expressed in the brain. According to the comprehensive behavioral battery, they exhibited less anxiety both in elevated plus maze and open field tests, mildly increased social approaching behavior in the reciprocal social interaction test, and longer latency to immobility in the tail suspension test as compared to wild-type (WT). Additionally, the extension of neurites in the primary cultured neurons was suppressed in ones derived from GAREM2 KO mice. Furthermore, we also identified Intersectin, as a binding partner of GAREM2 in this study. Intersectin is also a multi-domain adaptor protein that regulates endocytosis and cell signaling, which can potentially alter the subcellular localization of GAREM2. The important molecules, such as the neurotrophin receptor and Erk family, that are involved in the signaling pathway of the neural cell growth in the mouse brain, have been reported to participate in emotional behavior. As GAREM plays a role in the cellular growth factor receptor signaling pathway, GAREM2 may have a common role related to the transduction of Erk signaling in the higher brain functions.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder. Several genetic causes of ASD have been identified and this has enabled researchers to construct mouse models. Mouse behavioral tests reveal impaired social interaction and communication, as well as increased repetitive behavior and behavioral inflexibility in these mice, which correspond to core behavioral deficits observed in individuals with ASD. However, the connection between these behavioral abnormalities and the underlying dysregulation in neuronal circuits and synaptic function is poorly understood. Moreover, different components of the ASD phenotype may be linked to dysfunction in different brain regions, making it even more challenging to chart the pathophysiological mechanisms involved in ASD. Here we summarize the research on mouse models of ASD and their contribution to understanding pathophysiological mechanisms. Specifically, we emphasize abnormal serotonin production and regulation, as well as the disruption in circadian rhythms and sleep that are observed in a subset of ASD, and propose that spatiotemporal disturbances in brainstem development may be a primary cause of ASD that propagates towards the cerebral cortex.

Copy number variations on human chromosome 15q11-q13 have been implicated in several neurodevelopmental disorders. A paternal loss or duplication of the Prader-Willi syndrome/Angelman syndrome (PWS/AS) region confers a risk of obesity, although the mechanism remains a mystery due to a lack of an animal model that accurately recreates the obesity phenotype. We performed detailed analyses of mice with duplication of PWS/AS locus (6 Mb) generated by chromosome engineering and found that animals with a paternal duplication of this region (patDp/+) show late-onset obesity, high sensitivity for high-fat diet, high levels of blood leptin and insulin without an increase in food intake. We show that prior to becoming obese, young patDp/+ mice already had enlarged white adipocytes. Transcriptome analysis of adipose tissue revealed an up-regulation of Secreted frizzled-related protein 5 (Sfrp5), known to promote adipogenesis. We additionally generated a new mouse model of paternal duplication focusing on a 3 Mb region (3 Mb patDp/+) within the PWS/AS locus. These mice recapitulate the obese phenotypes including expansion of visceral adipose tissue. Our results suggest paternally expressed genes in PWS/AS locus play a significant role for the obesity and identify new potential targets for future research and treatment of obesity.

Genetic mutations contribute to the etiology of autism spectrum disorder (ASD), a common, heterogeneous neurodevelopmental disorder characterized by impairments in social interaction, communication, and repetitive and restricted patterns of behavior. Since neuroligin3 (NLGN3), a cell adhesion molecule at the neuronal synapse, was first identified as a risk gene for ASD, several additional variants in NLGN3 and NLGN4 were found in ASD patients. Moreover, synaptopathies are now known to cause several neuropsychiatric disorders including ASD. In humans, NLGNs consist of five family members, and neuroligin1 (NLGN1) is a major component forming a complex on excitatory glutamatergic synapses. However, the significance of NLGN1 in neuropsychiatric disorders remains unknown. Here, we systematically examine five missense variants of NLGN1 that were detected in ASD patients, and show molecular and cellular alterations caused by these variants. We show that a novel NLGN1 Pro89Leu (P89L) missense variant found in two ASD siblings leads to changes in cellular localization, protein degradation, and to the impairment of spine formation. Furthermore, we generated the knock-in P89L mice, and we show that the P89L heterozygote mice display abnormal social behavior, a core feature of ASD. These results, for the first time, implicate rare variants in NLGN1 as functionally significant and support that the NLGN synaptic pathway is of importance in the etiology of neuropsychiatric disorders., Author summary Autism spectrum disorder (ASD) is a childhood disorder manifested by abnormal social behavior, interests, and activities. The genetic contribution to ASD is higher than in other psychiatric disorders such as schizophrenia and mood disorders. Here, we found a novel mutation in NLGN1, a gene encoding a synaptic protein, in patients with ASD. We also developed a mouse model with this mutation, and showed that the model mouse exhibits abnormal social behavior. These results suggest that a rare variant in NLGN1 is functionally significant and support that the NLGN synaptic pathway may be important in the etiology of neuropsychiatric disorders. This humanized mouse model recapitulates some of the symptoms of patients with ASD and will serve as a valuable tool for therapeutic development.

Serotonin enhancement during developmental stages restores autism symptoms in a mouse model of human 15q11-13 duplication., Serotonin is a critical modulator of cortical function, and its metabolism is defective in autism spectrum disorder (ASD) brain. How serotonin metabolism regulates cortical physiology and contributes to the pathological and behavioral symptoms of ASD remains unknown. We show that normal serotonin levels are essential for the maintenance of neocortical excitation/inhibition balance, correct sensory stimulus tuning, and social behavior. Conversely, low serotonin levels in 15q dup mice (a model for ASD with the human 15q11-13 duplication) result in impairment of the same phenotypes. Restoration of normal serotonin levels in 15q dup mice revealed the reversibility of a subset of ASD-related symptoms in the adult. These findings suggest that serotonin may have therapeutic potential for discrete ASD symptoms.

The cellular components and function of the gastrointestinal epithelium exhibit distinct characteristics depending on the region, e.g., stomach or intestine. How these region-specific epithelial characteristics are generated during development remains poorly understood. Here, we report on the involvement of the helix-loop-helix inhibitor Id2 in establishing the specific characteristics of the intestinal epithelium. Id2−/− mice developed tumors in the small intestine. Histological analysis indicated that the intestinal tumors were derived from gastric metaplasia formed in the small intestine during development. Heterotopic Id2 expression in developing gastric epithelium induced a fate change to intestinal epithelium. Gene expression analysis revealed that foregut-enriched genes encoding Irx3 and Irx5 were highly induced in the midgut of Id2−/− embryos, and transgenic mice expressing Irx5 in the midgut endoderm developed tumors recapitulating the characteristics of Id2−/− mice. Altogether, our results demonstrate that Id2 plays a crucial role in the development of regional specificity in the gastrointestinal epithelium.

Signaling through the Ror2 receptor tyrosine kinase promotes invadopodia formation for tumor invasion. Here, we identify intraflagellar transport 20 (IFT20) as a new target of this signaling in tumors that lack primary cilia, and find that IFT20 mediates the ability of Ror2 signaling to induce the invasiveness of these tumors. We also find that IFT20 regulates the nucleation of Golgi-derived microtubules by affecting the GM130-AKAP450 complex, which promotes Golgi ribbon formation in achieving polarized secretion for cell migration and invasion. Furthermore, IFT20 promotes the efficiency of transport through the Golgi complex. These findings shed new insights into how Ror2 signaling promotes tumor invasiveness, and also advance the understanding of how Golgi structure and transport can be regulated.

Obesity is not only associated with unhealthy lifestyles, but also linked to genetic predisposition. Previously, we generated an autism mouse model (patDp/+) that carries a 6.3Mb paternal duplication homologous to the human 15q11–q13 locus. Chromosomal abnormalities in this region are known to cause autism spectrum disorder, Prader–Willi syndrome, and Angelman syndrome in humans. We found that, in addition to autistic-like behaviors, patDp/+ mice display late-onset obesity and hypersensitivity to a high-fat diet. These phenotypes are likely to be the results of genetic perturbations since the energy expenditures and food intakes of patDp/+ mice do not significantly differ from those of wild-type mice. Intriguingly, we found that an enlargement of adipose cells precedes the onset of obesity in patDp/+ mice. To understand the underlying molecular networks responsible for this pre-obese phenotype, we performed transcriptome profiling of white adipose tissue from patDp/+ and wild-type mice using microarray. We identified 230 genes as differentially expressed genes. Sfrp5 — a gene whose expression is positively correlated with adipocyte size, was found to be up-regulated, and Fndc5, a potent inducer of brown adipogenesis was identified to be the top down-regulated gene. Subsequent pathway analysis highlighted a set of 35 molecules involved in energy production, lipid metabolism, and small molecule biochemistry as the top candidate biological network responsible for the pre-obese phenotype of patDp/+. The microarray data were deposited in NCBI Gene Expression Omnibus database with accession number GSE58191. Ultimately, our dataset provides novel insights into the molecular mechanism of obesity and demonstrated that patDp/+ is a valuable mouse model for obesity research.

We consider the vertebrate somite segmentation clock as an example of a rhythmic phenomenon that occurs in development. Using mouse genetics and mathematical analyses, we found that the period of the clock in each presomitic cell is sensitive to Notch activity. It may be a system for each cell to adapt to its local environment., The number of vertebrae is defined strictly for a given species and depends on the number of somites, which are the earliest metameric structures that form in development. Somites are formed by sequential segmentation. The periodicity of somite segmentation is orchestrated by the synchronous oscillation of gene expression in the presomitic mesoderm (PSM), termed the “somite segmentation clock,” in which Notch signaling plays a crucial role. Here we show that the clock period is sensitive to Notch activity, which is fine-tuned by its feedback regulator, Notch-regulated ankyrin repeat protein (Nrarp), and that Nrarp is essential for forming the proper number and morphology of axial skeleton components. Null-mutant mice for Nrarp have fewer vertebrae and have defective morphologies. Notch activity is enhanced in the PSM of the Nrarp−/– embryo, where the ∼2-h segmentation period is extended by 5 min, thereby forming fewer somites and their resultant vertebrae. Reduced Notch activity partially rescues the Nrarp−/– phenotype in the number of somites, but not in morphology. Therefore we propose that the period of the somite segmentation clock is sensitive to Notch activity and that Nrarp plays essential roles in the morphology of vertebrae and ribs.

Genetic mutations contribute to the etiology of autism spectrum disorder (ASD), a common, heterogeneous neurodevelopmental disorder characterized by impairments in social interaction, communication, and repetitive and restricted patterns of behavior. Since neuroligin3 (NLGN3), a cell adhesion molecule at the neuronal synapse, was first identified as a risk gene for ASD, several additional variants in NLGN3 and NLGN4 were found in ASD patients. Moreover, synaptopathies are now known to cause several neuropsychiatric disorders including ASD. In humans, NLGNs consist of five family members, and neuroligin1 (NLGN1) is a major component forming a complex on excitatory glutamatergic synapses. However, the significance of NLGN1 in neuropsychiatric disorders remains unknown. Here, we systematically examine five missense variants of NLGN1 that were detected in ASD patients, and show molecular and cellular alterations caused by these variants. We show that a novel NLGN1 Pro89Leu (P89L) missense variant found in two ASD siblings leads to changes in cellular localization, protein degradation, and to the impairment of spine formation. Furthermore, we generated the knock-in P89L mice, and we show that the P89L heterozygote mice display abnormal social behavior, a core feature of ASD. These results, for the first time, implicate rare variants in NLGN1 as functionally significant and support that the NLGN synaptic pathway is of importance in the etiology of neuropsychiatric disorders.

The receptor tyrosine kinase Ror2 regulates cell migration by acting as a receptor or co-receptor for Wnt5a. Although Wnt5a has been implicated in the invasiveness of several types of tumors, the role of Ror2 in tumor invasion remains elusive. Here we show that osteosarcoma cell lines SaOS-2 and U2OS show invasive properties in vitro by activating Wnt5a/Ror2 signaling in a cell-autonomous manner. The suppressed expression of either Wnt5a or Ror2 in osteosarcoma cells inhibits cell invasiveness accompanying decreased invadopodia formation. Gene-expression profiling identified matrix metalloproteinase 13 (MMP-13) as one of the genes whose expression is downregulated in SaOS-2 cells following suppression of Ror2 expression. Reduced expression or activity of MMP-13 suppresses invasiveness of SaOS-2 cells. Moreover, expression of MMP-13 and cell invasiveness by Wnt5a/Ror2 signaling can be abrogated by an inhibitor of the Src-family protein tyrosine kinases (SFKs), suggesting the role of the SFKs in MMP-13 expression through Wnt5a/Ror2 signaling. We further show that activation of an SFK is inhibited by the suppressed expression of Ror2. Collectively, these results indicate that Wnt5a/Ror2 signaling involves the activation of a SFK, leading to MMP-13 expression, and that constitutively active Wnt5a/Ror2 signaling confers invasive properties on osteosarcoma cells in a cell-autonomous manner.

Autism is a complex psychiatric illness that has received considerable attention as a developmental brain disorder. Substantial evidence suggests that chromosomal abnormalities contribute to the risk of autism. The duplication of human chromosome 15q11-13 is known to be the most frequent cytogenetic abnormality in autism. We have modeled this genetic change in mice using chromosome engineering to generate a 6.3-Mb duplication of the conserved linkage group on mouse chromosome 7. Mice with a paternal duplication display autistic behavioral features such as poor social interaction, behavioral inflexibility, abnormal ultrasonic vocalizations, and correlates of anxiety. An increased MBII52 snoRNA within the duplicated region, affecting the serotonin 2c receptor (5-HT2cR), correlates with altered intracellular Ca2+ responses elicited by a 5-HT2cR agonist in the neurons in mice with a paternal duplication. This first chromosome-engineered mouse model for autism replicates various aspects of human autistic phenotypes and validates the relevance of the human chromosome abnormality. This model will facilitate forward genetics of developmental brain disorders and serve as an invaluable tool for therapeutic development.

Autism spectrum disorders (ASDs) have garnered significant attention as an important grouping of developmental brain disorders. Recent genomic studies have revealed that inherited or de novo copy number variations (CNVs) are significantly involved in the pathophysiology of ASDs. In a previous report from our laboratory, we generated mice with CNVs as a model of ASDs, with a duplicated mouse chromosome 7C that is orthologous to human chromosome 15q11-13. Behavioral analyses revealed paternally duplicated (patDp/+) mice displayed abnormal behaviors resembling the symptoms of ASDs. In the present study, we extended these findings by performing various behavioral tests with C57BL/6J patDp/+ mice, and comprehensively measuring brain monoamine levels with ex vivo high performance liquid chromatography. Compared with wild-type controls, patDp/+ mice exhibited decreased locomotor and exploratory activities in the open field test, Y-maze test, and fear-conditioning test. Furthermore, their decreased activity levels overcame increased appetite induced by 24 hours of food deprivation in the novelty suppressed feeding test. Serotonin levels in several brain regions of adult patDp/+ mice were lower than those of wild-type control, with no concurrent changes in brain levels of dopamine or norepinephrine. Moreover, analysis of monoamines in postnatal developmental stages demonstrated reduced brain levels of serotonin in young patDp/+ mice. These findings suggest that a disrupted brain serotonergic system, especially during postnatal development, may generate the phenotypes of patDp/+ mice.