Enhanced polyubiquitination of Shank3 and NMDA receptor in a mouse model of autism.

We have created a mouse genetic model that mimics a human mutation of Shank3 that deletes the C terminus and is associated with autism. Expressed as a single copy [Shank3(+/ΔC) mice], Shank3ΔC protein interacts with the wild-type (WT) gene product and results in >90% reduction of Shank3 at synapses. This "gain-of-function" phenotype is linked to increased polyubiquitination of WT Shank3 and its redistribution into proteasomes. Similarly, the NR1 subunit of the NMDA receptor is reduced at synapses with increased polyubiquitination. Assays of postsynaptic density proteins, spine morphology, and synapse number are unchanged in Shank3(+/ΔC) mice, but the amplitude of NMDAR responses is reduced together with reduced NMDAR-dependent LTP and LTD. Reciprocally, mGluR-dependent LTD is markedly enhanced. Shank3(+/ΔC) mice show behavioral deficits suggestive of autism and reduced NMDA receptor function. These studies reveal a mechanism distinct from haploinsufficiency by which mutations of Shank3 can evoke an autism-like disorder.

Strong evidence for genotype-phenotype correlations in Phelan-McDermid syndrome: results from the developmental synaptopathies consortium.

Individuals with Phelan-McDermid syndrome (PMS) present with a wide range of developmental, medical, cognitive and behavioral abnormalities. Previous literature has begun to elucidate genotype-phenotype associations that may contribute to the wide spectrum of features. Here, we report results of genotype-phenotype associations in a cohort of 170 individuals with PMS. Genotypes were defined as Class I deletions (including SHANK3 only or SHANK3 with ARSA and/or ACR and RABL2B), Class II deletions (all other deletions) or sequence variants. Phenotype data were derived prospectively from direct evaluation, caregiver interview and questionnaires, and medical history. Analyses revealed individuals with Class I deletions or sequence variants had fewer delayed developmental milestones and higher cognitive ability compared to those with Class II deletions but had more skill regressions. Individuals with Class II deletions were more likely to have a variety of medical features, including renal abnormalities, spine abnormalities, and ataxic gait. Those with Class I deletions or sequence variants were more likely to have psychiatric diagnoses including bipolar disorder, depression, and schizophrenia. Autism spectrum disorder diagnoses did not differ between groups. This study represents the largest and most rigorous genotype-phenotype analysis in PMS to date and provides important information for considering clinical functioning, trajectories and comorbidities as a function of specific genetic alteration.

Kctd13 deletion reduces synaptic transmission via increased RhoA.

Copy-number variants of chromosome 16 region 16p11.2 are linked to neuropsychiatric disorders and are among the most prevalent in autism spectrum disorders. Of many 16p11.2 genes, Kctd13 has been implicated as a major driver of neurodevelopmental phenotypes. The function of KCTD13 in the mammalian brain, however, remains unknown. Here we delete the Kctd13 gene in mice and demonstrate reduced synaptic transmission. Reduced synaptic transmission correlates with increased levels of Ras homolog gene family, member A (RhoA), a KCTD13/CUL3 ubiquitin ligase substrate, and is reversed by RhoA inhibition, suggesting increased RhoA as an important mechanism. In contrast to a previous knockdown study, deletion of Kctd13 or kctd13 does not increase brain size or neurogenesis in mice or zebrafish, respectively. These findings implicate Kctd13 in the regulation of neuronal function relevant to neuropsychiatric disorders and clarify the role of Kctd13 in neurogenesis and brain size. Our data also reveal a potential role for RhoA as a therapeutic target in disorders associated with KCTD13 deletion.

Foxp1 in Forebrain Pyramidal Neurons Controls Gene Expression Required for Spatial Learning and Synaptic Plasticity.

Genetic perturbations of the transcription factor Forkhead Box P1 (FOXP1) are causative for severe forms of autism spectrum disorder that are often comorbid with intellectual disability. Recent work has begun to reveal an important role for FoxP1 in brain development, but the brain-region-specific contributions of Foxp1 to autism and intellectual disability phenotypes have yet to be determined fully. Here, we describe Foxp1 conditional knock-out (Foxp1cKO) male and female mice with loss of Foxp1 in the pyramidal neurons of the neocortex and the CA1/CA2 subfields of the hippocampus. Foxp1cKO mice exhibit behavioral phenotypes that are of potential relevance to autism spectrum disorder, including hyperactivity, increased anxiety, communication impairments, and decreased sociability. In addition, Foxp1cKO mice have gross deficits in learning and memory tasks of relevance to intellectual disability. Using a genome-wide approach, we identified differentially expressed genes in the hippocampus of Foxp1cKO mice associated with synaptic function and development. Furthermore, using magnetic resonance imaging, we uncovered a significant reduction in the volumes of both the entire hippocampus as well as individual hippocampal subfields of Foxp1cKO mice. Finally, we observed reduced maintenance of LTP in area CA1 of the hippocampus in these mutant mice. Together, these data suggest that proper expression of Foxp1 in the pyramidal neurons of the forebrain is important for regulating gene expression pathways that contribute to specific behaviors reminiscent of those seen in autism and intellectual disability. In particular, Foxp1 regulation of gene expression appears to be crucial for normal hippocampal development, CA1 plasticity, and spatial learning.SIGNIFICANCE STATEMENT Loss-of-function mutations in the transcription factor Forkhead Box P1 (FOXP1) lead to autism spectrum disorder and intellectual disability. Understanding the potential brain-region-specific contributions of FOXP1 to disease-relevant phenotypes could be a critical first step in the management of patients with these mutations. Here, we report that Foxp1 conditional knock-out (Foxp1cKO) mice with loss of Foxp1 in the neocortex and hippocampus display autism and intellectual-disability-relevant behaviors. We also show that these phenotypes correlate with changes in both the genomic and physiological profiles of the hippocampus in Foxp1cKO mice. Our work demonstrates that brain-region-specific FOXP1 expression may relate to distinct, clinically relevant phenotypes.

Spatial gene expression analysis of neuroanatomical differences in mouse models.

MRI is a powerful modality to detect neuroanatomical differences that result from mutations and treatments. Knowing which genes drive these differences is important in understanding etiology, but candidate genes are often difficult to identify. We tested whether spatial gene expression data from the Allen Brain Institute can be used to inform us about genes that cause neuroanatomical differences. For many single-gene-mutation mouse models, we found that affected neuroanatomy was not strongly associated with the spatial expression of the altered gene and there are specific caveats for each model. However, among models with significant neuroanatomical differences from their wildtype controls, the mutated genes had preferential spatial expression in affected neuroanatomy. In mice exposed to environmental enrichment, candidate genes could be identified by a genome-wide search for genes with preferential spatial expression in the altered neuroanatomical regions. These candidates have functions related to learning and plasticity. We demonstrate that spatial gene expression of single-genes is a poor predictor of altered neuroanatomy, but altered neuroanatomy can identify candidate genes responsible for neuroanatomical phenotypes.

Autism-Associated Insertion Mutation (InsG) of Shank3 Exon 21 Causes Impaired Synaptic Transmission and Behavioral Deficits.

SHANK3 (also known as PROSAP2) is a postsynaptic scaffolding protein at excitatory synapses in which mutations and deletions have been implicated in patients with idiopathic autism, Phelan-McDermid (aka 22q13 microdeletion) syndrome, and other neuropsychiatric disorders. In this study, we have created a novel mouse model of human autism caused by the insertion of a single guanine nucleotide into exon 21 (Shank3(G)). The resulting frameshift causes a premature STOP codon and loss of major higher molecular weight Shank3 isoforms at the synapse. Shank3(G/G) mice exhibit deficits in hippocampus-dependent spatial learning, impaired motor coordination, altered response to novelty, and sensory processing deficits. At the cellular level, Shank3(G/G) mice also exhibit impaired hippocampal excitatory transmission and plasticity as well as changes in baseline NMDA receptor-mediated synaptic responses. This work identifies clear alterations in synaptic function and behavior in a novel, genetically accurate mouse model of autism mimicking an autism-associated insertion mutation. Furthermore, these findings lay the foundation for future studies aimed to validate and study region-selective and temporally selective genetic reversal studies in the Shank3(G/G) mouse that was engineered with such future experiments in mind.

Loss of predominant Shank3 isoforms results in hippocampus-dependent impairments in behavior and synaptic transmission.

The Shank3 gene encodes a scaffolding protein that anchors multiple elements of the postsynaptic density at the synapse. Previous attempts to delete the Shank3 gene have not resulted in a complete loss of the predominant naturally occurring Shank3 isoforms. We have now characterized a homozygous Shank3 mutation in mice that deletes exon 21, including the Homer binding domain. In the homozygous state, deletion of exon 21 results in loss of the major naturally occurring Shank3 protein bands detected by C-terminal and N-terminal antibodies, allowing us to more definitively examine the role of Shank3 in synaptic function and behavior. This loss of Shank3 leads to an increased localization of mGluR5 to both synaptosome and postsynaptic density-enriched fractions in the hippocampus. These mice exhibit a decrease in NMDA/AMPA excitatory postsynaptic current ratio in area CA1 of the hippocampus, reduced long-term potentiation in area CA1, and deficits in hippocampus-dependent spatial learning and memory. In addition, these mice also exhibit motor-coordination deficits, hypersensitivity to heat, novelty avoidance, altered locomotor response to novelty, and minimal social abnormalities. These data suggest that Shank3 isoforms are required for normal synaptic transmission/plasticity in the hippocampus, as well as hippocampus-dependent spatial learning and memory.

Developmental and adult GAP-43 deficiency in mice dynamically alters hippocampal neurogenesis and mossy fiber volume.

Growth-associated protein-43 (GAP-43) is a presynaptic protein that plays key roles in axonal growth and guidance and in modulating synapse formation. Previous work has demonstrated that mice lacking one allele of this gene (GAP-43+/- mice) exhibit hippocampal structural abnormalities, impaired spatial learning and stress-induced behavioral withdrawal and anxiety, behaviors that are dependent on proper hippocampal circuitry and function. Given the correlation between hippocampal function, synaptic connectivity and neurogenesis, we tested if behaviorally naïve GAP-43+/- mice had alterations in either neurogenesis or synaptic connectivity in the hippocampus during early postnatal development and young adulthood, and following behavior testing in older adults. To test our hypothesis, we examined hippocampal cell proliferation (Ki67), number of immature neuroblasts (doublecortin, DCX) and mossy fiber volume (synaptoporin) in behaviorally naïve postnatal day 9 (P9) and P26, and behaviorally experienced 5- to 7-month-old GAP-43+/- and +/+ littermate mice. P9 GAP-43+/- mice had fewer Ki67+ and DCX+ cells compared to +/+ mice, particularly in the posterior dentate gyrus, and smaller mossy fiber volume in the same region. In young adulthood, however, male GAP-43+/- mice had more Ki67+ and DCX+ cells and greater mossy fiber volume in the posterior dentate gyrus relative to male +/+ mice. These increases were not seen in females. In 5- to 7-month-old GAP-43+/- mice (whose behaviors were the focus of our prior publication), there was no global change in the number of proliferating or immature neurons relative to +/+ mice. However, more detailed analysis revealed fewer proliferative DCX+ cells in the anterior dentate gyrus of male GAP-43+/- mice compared to male +/+ mice. This reduction was not observed in females. These results suggest that young GAP-43+/- mice have decreased hippocampal neurogenesis and synaptic connectivity, but slightly older mice have greater hippocampal neurogenesis and synaptic connectivity. In conjunction with our previous study, these findings suggest that GAP-43 is dynamically involved in early postnatal and adult hippocampal neurogenesis and synaptic connectivity, possibly contributing to the GAP-43+/- behavioral phenotype.

Autism risk gene Cul3 alters neuronal morphology via caspase-3 activity in mouse hippocampal neurons.

Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders (NDDs) in which children display differences in social interaction/communication and repetitive stereotyped behaviors along with variable associated features. Cul3, a gene linked to ASD, encodes CUL3 (CULLIN-3), a protein that serves as a key component of a ubiquitin ligase complex with unclear function in neurons. Cul3 homozygous deletion in mice is embryonic lethal; thus, we examine the role of Cul3 deletion in early synapse development and neuronal morphology in hippocampal primary neuronal cultures. Homozygous deletion of Cul3 significantly decreased dendritic complexity and dendritic length, as well as axon formation. Synaptic spine density significantly increased, mainly in thin and stubby spines along with decreased average spine volume in Cul3 knockouts. Both heterozygous and homozygous knockout of Cul3 caused significant reductions in the density and colocalization of gephyrin/vGAT puncta, providing evidence of decreased inhibitory synapse number, while excitatory synaptic puncta vGulT1/PSD95 density remained unchanged. Based on previous studies implicating elevated caspase-3 after Cul3 deletion, we demonstrated increased caspase-3 in our neuronal cultures and decreased neuronal cell viability. We then examined the efficacy of the caspase-3 inhibitor Z-DEVD-FMK to rescue the decrease in neuronal cell viability, demonstrating reversal of the cell viability phenotype with caspase-3 inhibition. Studies have also implicated caspase-3 in neuronal morphological changes. We found that caspase-3 inhibition largely reversed the dendrite, axon, and spine morphological changes along with the inhibitory synaptic puncta changes. Overall, these data provide additional evidence that Cul3 regulates the formation or maintenance of cell morphology, GABAergic synaptic puncta, and neuronal viability in developing hippocampal neurons in culture.

Clinical, genetic, and cognitive correlates of seizure occurrences in Phelan-McDermid syndrome.

BACKGROUND: Phelan-McDermid syndrome (PMS) is a genetic neurodevelopmental disorder caused by SHANK3 haploinsufficiency and is associated with an increased risk for seizures. Previous literature indicates that around one third of individuals with PMS also have epilepsy or seizures, with a wide range of types and ages of onset. Investigating the impact of seizures on intellectual and adaptive functioning for PMS is a primary concern for caregivers and is important to understanding the natural history of this syndrome. METHODS: We report on results from 98 individuals enrolled in a prospective, longitudinal study. We detailed seizure frequency, type, and age of onset, and we analyzed seizure occurrence with best estimate IQ, adaptive functioning, clinical features, and genotype. We conducted multiple linear regression analyses to assess the relationship between the presence of seizures and the Vineland Adaptive Behavior Scale, Second Edition (VABS-II) Adaptive Behavior Composite score and the best estimate full-scale IQ. We also performed Chi-square tests to explore associations between seizure prevalence and genetic groupings. Finally, we performed Chi-square tests and t-tests to explore the relationship between seizures and demographic features, features that manifest in infancy, and medical features. RESULTS: Seizures were present in 41% of the cohort, and age of onset was widely variable. The presence of seizures was associated with significantly lower adaptive and intellectual functioning. Genotype-phenotype analyses were discrepant, with no differences in seizure prevalence across genetic classes, but with more genes included in deletions of participants with 22q13 deletions and seizures compared to those with 22q13 deletions and no seizures. No clinical associations were found between the presence of seizures and sex, history of pre- or neonatal complications, early infancy, or medical features. In this cohort, generalized seizures were associated with developmental regression, which is a top concern for PMS caregivers. CONCLUSIONS: These results begin to eludicate correlates of seizures in individuals with PMS and highlight the importance of early seizure management. Importantly, presence of seizures was associated with adaptive and cognitive functioning. A larger cohort might be able to identify additional associations with medical features. Genetic findings suggest an increased capability to realize genotype-phenotype relationships when deletion size is taken into account.

Functional and mechanistic exploration of an adult neurogenesis-promoting small molecule.

Adult neurogenesis occurs throughout life in the mammalian hippocampus and is essential for memory and mood control. There is significant interest in identifying ways to promote neurogenesis and ensure maintenance of these hippocampal functions. Previous work with a synthetic small molecule, isoxazole 9 (Isx-9), highlighted its neuronal-differentiating properties in vitro. However, the ability of Isx-9 to drive neurogenesis in vivo or improve hippocampal function was unknown. Here we show that Isx-9 promotes neurogenesis in vivo, enhancing the proliferation and differentiation of hippocampal subgranular zone (SGZ) neuroblasts, and the dendritic arborization of adult-generated dentate gyrus neurons. Isx-9 also improves hippocampal function, enhancing memory in the Morris water maze. Notably, Isx-9 enhances neurogenesis and memory without detectable increases in cellular or animal activity or vascularization. Molecular exploration of Isx-9-induced regulation of neurogenesis (via FACS and microarray of SGZ stem and progenitor cells) suggested the involvement of the myocyte-enhancer family of proteins (Mef2). Indeed, transgenic-mediated inducible knockout of all brain-enriched Mef2 isoforms (Mef2a/c/d) specifically from neural stem cells and their progeny confirmed Mef2's requirement for Isx-9-induced increase in hippocampal neurogenesis. Thus, Isx-9 enhances hippocampal neurogenesis and memory in vivo, and its effects are reliant on Mef2, revealing a novel cell-intrinsic molecular pathway regulating adult neurogenesis.

Effects of heterozygous deletion of autism-related gene Cullin-3 in mice.

Autism Spectrum Disorder (ASD) is a developmental disorder in which children display repetitive behavior, restricted range of interests, and atypical social interaction and communication. CUL3, coding for a Cullin family scaffold protein mediating assembly of ubiquitin ligase complexes through BTB domain substrate-recruiting adaptors, has been identified as a high-risk gene for autism. Although complete knockout of Cul3 results in embryonic lethality, Cul3 heterozygous mice have reduced CUL3 protein, demonstrate comparable body weight, and display minimal behavioral differences including decreased spatial object recognition memory. In measures of reciprocal social interaction, Cul3 heterozygous mice behaved similarly to their wild-type littermates. In area CA1 of hippocampus, reduction of Cul3 significantly increased mEPSC frequency but not amplitude nor baseline evoked synaptic transmission or paired-pulse ratio. Sholl and spine analysis data suggest there is a small yet significant difference in CA1 pyramidal neuron dendritic branching and stubby spine density. Unbiased proteomic analysis of Cul3 heterozygous brain tissue revealed dysregulation of various cytoskeletal organization proteins, among others. Overall, our results suggest that Cul3 heterozygous deletion impairs spatial object recognition memory, alters cytoskeletal organization proteins, but does not cause major hippocampal neuronal morphology, functional, or behavioral abnormalities in adult global Cul3 heterozygous mice.

Reversal of memory and autism-related phenotypes in Tsc2+/- mice via inhibition of Nlgn1.

Tuberous sclerosis complex (TSC) is a rare monogenic disorder co-diagnosed with high rates of autism and is caused by loss of function mutations in the TSC1 or TSC2 genes. A key pathway hyperactivated in TSC is the mammalian/mechanistic target of rapamycin complex 1 (mTORC1), which regulates cap-dependent mRNA translation. We previously demonstrated that exaggerated cap-dependent translation leads to autism-related phenotypes and increased mRNA translation and protein expression of Neuroligin 1 (Nlgn1) in mice. Inhibition of Nlgn1 expression reversed social behavior deficits in mice with increased cap-dependent translation. Herein, we report elevated translation of Nlgn1 mRNA and an increase in its protein expression. Genetic or pharmacological inhibition of Nlgn1 expression in Tsc2 +/- mice rescued impaired hippocampal mGluR-LTD, contextual discrimination and social behavior deficits in Tsc2 +/- mice, without correcting mTORC1 hyperactivation. Thus, we demonstrate that reduction of Nlgn1 expression in Tsc2 +/- mice is a new therapeutic strategy for TSC and potentially other neurodevelopmental disorders.

Large 22q13.3 deletions perturb peripheral transcriptomic and metabolomic profiles in Phelan-McDermid syndrome.

Phelan-McDermid syndrome (PMS) is a rare neurodevelopmental disorder caused at least in part by haploinsufficiency of the SHANK3 gene, due to sequence variants in SHANK3 or subtelomeric 22q13.3 deletions. Phenotypic differences have been reported between PMS participants carrying small "class I" mutations and large "class II" mutations; however, the molecular perturbations underlying these divergent phenotypes remain obscure. Using peripheral blood transcriptome and serum metabolome profiling, we examined the molecular perturbations in the peripheral circulation associated with a full spectrum of PMS genotypes spanning class I (n = 37) and class II mutations (n = 39). Transcriptomic data revealed 52 genes with blood expression profiles that tightly scale with 22q.13.3 deletion size. Furthermore, we uncover 208 underexpressed genes in PMS participants with class II mutations, which were unchanged in class I mutations. These genes were not linked to 22q13.3 and were strongly enriched for glycosphingolipid metabolism, NCAM1 interactions, and cytotoxic natural killer (NK) immune cell signatures. In silico predictions estimated a reduction in CD56+ CD16- NK cell proportions in class II mutations, which was validated by mass cytometry time of flight. Global metabolomics profiling identified 24 metabolites that were significantly altered in PMS participants with class II mutations and confirmed a general reduction in sphingolipid metabolism. Collectively, these results provide new evidence linking PMS participants carrying class II mutations with decreased expression of cytotoxic cell signatures, reduced relative proportions of NK cells, and lower sphingolipid metabolism. These findings highlight alternative avenues for therapeutic development and offer new mechanistic insights supporting genotype-to-phenotype associations in PMS.

Temporally specified genetic ablation of neurogenesis impairs cognitive recovery after traumatic brain injury.

Significant spontaneous recovery occurs after essentially all forms of serious brain injury, although the mechanisms underlying this recovery are unknown. Given that many forms of brain injury such as traumatic brain injury (TBI) induce hippocampal neurogenesis, we investigated whether these newly generated neurons might play a role in recovery. By modeling TBI in transgenic mice, we determined that injury-induced newly generated neurons persisted over time and elaborated extensive dendritic trees that stably incorporated themselves throughout all neuronal layers of the dentate gyrus. When we selectively ablated dividing stem/progenitors at the time of injury with ganciclovir in a nestin-HSV-TK transgenic model, we eliminated injury-induced neurogenesis and subsequently diminished the progenitor pool. Moreover, using hippocampal-specific behavioral tests, we demonstrated that only injured animals with neurogenesis ablated at the time of injury lost the ability to learn spatial memory tasks. These data demonstrate a functional role for adult neurogenesis after brain injury and offer compelling and testable therapeutic options that might enhance recovery.

Deletion of the hyperpolarization-activated cyclic nucleotide-gated channel auxiliary subunit TRIP8b impairs hippocampal Ih localization and function and promotes antidepressant behavior in mice.

Output properties of neurons are greatly shaped by voltage-gated ion channels, whose biophysical properties and localization within axodendritic compartments serve to significantly transform the original input. The hyperpolarization-activated current, I(h), is mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and plays a fundamental role in influencing neuronal excitability by regulating both membrane potential and input resistance. In neurons such as cortical and hippocampal pyramidal neurons, the subcellular localization of HCN channels plays a critical functional role, yet mechanisms controlling HCN channel trafficking are not fully understood. Because ion channel function and localization are often influenced by interacting proteins, we generated a knock-out mouse lacking the HCN channel auxiliary subunit, tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b). Eliminating expression of TRIP8b dramatically reduced I(h) expression in hippocampal pyramidal neurons. Loss of I(h)-dependent membrane voltage properties was attributable to reduction of HCN channels on the neuronal surface, and there was a striking disruption of the normal expression pattern of HCN channels in pyramidal neuron dendrites. In heterologous cells and neurons, absence of TRIP8b increased HCN subunit targeting to and degradation by lysosomes. Mice lacking TRIP8b demonstrated motor learning deficits and enhanced resistance to multiple tasks of behavioral despair with high predictive validity for antidepressant efficacy. We observed similar resistance to behavioral despair in distinct mutant mice lacking HCN1 or HCN2. These data demonstrate that interaction with the auxiliary subunit TRIP8b is a major mechanism underlying proper expression of HCN channels and I(h) in vivo, and suggest that targeting I(h) may provide a novel approach to treatment of depression.

Mouse neurexin-1alpha deletion causes correlated electrophysiological and behavioral changes consistent with cognitive impairments.

Deletions in the neurexin-1alpha gene were identified in large-scale unbiased screens for copy-number variations in patients with autism or schizophrenia. To explore the underlying biology, we studied the electrophysiological and behavioral phenotype of mice lacking neurexin-1alpha. Hippocampal slice physiology uncovered a defect in excitatory synaptic strength in neurexin-1alpha deficient mice, as revealed by a decrease in miniature excitatory postsynaptic current (EPSC) frequency and in the input-output relation of evoked postsynaptic potentials. This defect was specific for excitatory synaptic transmission, because no change in inhibitory synaptic transmission was observed in the hippocampus. Behavioral studies revealed that, compared with littermate control mice, neurexin-1alpha deficient mice displayed a decrease in prepulse inhibition, an increase in grooming behaviors, an impairment in nest-building activity, and an improvement in motor learning. However, neurexin-1alpha deficient mice did not exhibit any obvious changes in social behaviors or in spatial learning. Together, these data indicate that the neurexin-1alpha deficiency induces a discrete neural phenotype whose extent correlates, at least in part, with impairments observed in human patients.

"Déjà vu" in an autism gene mouse model modifies social mores.

Genetic and environmental factors during development are involved in autism, and in this issue of Neuron Krüttner et al. (2022) find environment may play a more acute role in modulating autism behavior in a Shank3 exon 21 deletion mutant mouse (Shank3ΔC/ΔC). The authors explore the underlying circuit mechanisms in detail.

Subcutaneous Administration of a Nitric Oxide-Releasing Nanomatrix Gel Ameliorates Obesity and Insulin Resistance in High-Fat Diet-Induced Obese Mice.

Nitric oxide (NO) is a gaseous signaling molecule, which plays crucial roles in various biological processes, including inflammatory responses, metabolism, cardiovascular functions, and cognitive function. NO bioavailability is reduced with aging and cardiometabolic disorders in humans and rodents. NO stimulates the metabolic rate by increasing the mitochondrial biogenesis and brown fat activation. Therefore, we propose a novel technology of providing exogenous NO to improve the metabolic rate and cognitive function by promoting the development of brown adipose tissue. In the present study, we demonstrate the effects of the peptide amphiphiles-NO-releasing nanomatrix gel (PANO gel) on high-fat diet-induced obesity, insulin resistance, and cognitive functions. Eight-week-old male C57BL/6 mice were subcutaneously injected in the brown fat area with the PANO gel or vehicle (PA gel) every 2 weeks for 12 weeks. The PANO gel-injected mice gained less body weight, improved glucose tolerance, and decreased fasting serum insulin and leptin levels compared with the PA gel-injected mice. Insulin signaling in the muscle, liver, and epididymal white adipose tissue was improved by the PANO gel injection. The PANO gel reduced inflammation, increased lipolysis in the epididymal white adipose tissue, and decreased serum lipids and liver triglycerides. Interestingly, the PANO gel stimulated uncoupled protein 1 gene expression in the brown and beige fat tissues. Furthermore, the PANO gel increased the cerebral blood flow and improved learning and memory abilities. Our results suggest that using the PANO gel to supply exogenous NO is a novel technology to treat metabolic disorders and cognitive dysfunctions.