NLGN1 and NLGN2 in the prefrontal cortex: their role in memory consolidation and strengthening

Plasticity mechanisms of genetically distinct Purkinje cells

Despite its uniform appearance, the cerebellar cortex is highly heterogeneous in terms of structure, genetics and physiology. Purkinje cells (PCs), the principal and sole output neurons of the cerebellar cortex, can be categorized into multiple populations that differentially express molecular markers and display distinctive physiological features. Such features include action potential rate, but also their propensity for synaptic and intrinsic plasticity. However, the precise molecular and genetic factors that correlate with the differential physiological properties of PCs remain elusive. In this article, we provide a detailed overview of the cellular mechanisms that regulate PC activity and plasticity. We further perform a pathway analysis to highlight how molecular characteristics of specific PC populations may influence their physiology and plasticity mechanisms.

Lung transcriptomics reveals the underlying mechanism by which aerobic training enhances pulmonary function in chronic obstructive pulmonary disease

BACKGROUND

Aerobic training is the primary method of rehabilitation for improving respiratory function in patients with chronic obstructive pulmonary disease (COPD) in remission. However, the mechanism underlying this improvement is not yet fully understood. The use of transcriptomics in rehabilitation medicine offers a promising strategy for uncovering the ways in which exercise training improves respiratory dysfunction in COPD patients. In this study, lung tissue was analyzed using transcriptomics to investigate the relationship between exercise and lung changes.

METHODS

Mice were exposed to cigarette smoke for 24 weeks, followed by nine weeks of moderate-intensity treadmill exercise, with a control group for comparison. Pulmonary function and structure were assessed at the end of the intervention and RNA sequencing was performed on the lung tissue.

RESULTS

Exercise training was found to improve airway resistance and lung ventilation indices in individuals exposed to cigarette smoke. However, the effect of this treatment on damaged alveoli was weak. The pair-to-pair comparison revealed numerous differentially expressed genes, that were closely linked to inflammation and metabolism.

CONCLUSIONS

Further research is necessary to confirm the cause-and-effect relationship between the identified biomarkers and the improvement in pulmonary function, as this was not examined in the present study.

The effects of maternal care on the developmental transcriptome and metatranscriptome of a wild bee

Maternal care acts as a strong environmental stimulus that can induce phenotypic plasticity in animals and may also alter their microbial communities through development. Here, we characterize the developmental metatranscriptome of the small carpenter bee, Ceratina calcarata, across developmental stages and in the presence or absence of mothers. Maternal care had the most influence during early development, with the greatest number and magnitude of differentially expressed genes between maternal care treatments, and enrichment for transcription factors regulating immune response in motherless early larvae. Metatranscriptomic data revealed fungi to be the most abundant group in the microbiome, with Aspergillus the most abundant in early larvae raised without mothers. Finally, integrative analysis between host transcriptome and metatranscriptome highlights several fungi correlating with developmental and immunity genes. Our results provide characterizations of the influence of maternal care on gene expression and the microbiome through development in a wild bee.

The role of the dorsal hippocampus in resistance to the development of posttraumatic stress disorder-like behaviours

This study aimed to determine the activity of the dorsal hippocampus (dHIP) in resistance to the development of posttraumatic stress disorder (PTSD)-like behaviours. Rats were divided into resistant, PTSD(-), and susceptible, PTSD(+) groups based on the time spent in the central area in an open field test and freezing duration during exposure to an aversive context one week after stress experience (electric foot shock). The PTSD(-) rats, compared to the PTSD(+) group, had an increased concentration of corticosterone in plasma and changes in the activity of the dHIP, specifically, increased c-Fos expression in the dentate gyrus (DG) and increased Neuroligin-2 (marker of GABAergic neurotransmission) expression in the DG and CA3 area of the dHIP. Moreover, in the hippocampus, the PTSD(-) group showed decreased mRNA expression for corticotropin-releasing factor receptors type 1 and 2, increased mRNA expression for orexin receptor type 1, and decreased miR-9 and miR-34c levels compared with the PTSD(+) group. This study may suggest that the increase in GABA signalling in the hippocampus attenuates the activity of the CRF system and enhances the function of the orexin system. Moreover, decreased expression of miR-34c and miR-9 could facilitate fear extinction and diminishes the anxiety response. These effects may lead to an anxiolytic-like effect and improve resistance to developing PTSD-like behaviours.

Like a rolling stone: Psychotherapy without (episodic) memory

People with profound amnesia still retain the capacity to learn about the emotional value of experiences, which is crucial in developing and sustaining interpersonal relationships. In a 2017 paper, we demonstrated for the first time (with patient JL) that transferential feelings develop across the therapeutic process, despite profound episodic memory impairment after medial temporal lesions. This paper reports a second case (GA) of a profoundly amnesic patient in psychotherapy, this time after lesions to the anterior fornix. The work with GA opens issues such as the differences and similarities to the previous case, counter-transference phenomena, and the effects of hyperphagia. The findings make it clear that many phenomena are common to both GA and JL, such as forgetfulness, various types of repetition, the importance of the therapeutic alliance, and the ability to make therapeutic gain. However, there were differences between the cases, for example as regards confabulation, which may relate to either pre-morbid personality or lesion site. The paper also discusses the way in which patients of this type bear the very status of psychotherapeutic work with profoundly amnesic patients. Where others have seen barriers and in principle problems in working with such patients, we see many opportunities.

Genetic Overlap Analysis Identifies a Shared Etiology between Migraine and Headache with Type 2 Diabetes

Migraine and headache frequently co-occur with type 2 diabetes (T2D), suggesting a shared aetiology between the two conditions. We used genome-wide association study (GWAS) data to investigate the genetic overlap and causal relationship between migraine and headache with T2D. Using linkage disequilibrium score regression (LDSC), we found a significant genetic correlation between migraine and T2D (rg = 0.06, p = 1.37 × 10−5) and between headache and T2D (rg = 0.07, p = 3.0 × 10−4). Using pairwise GWAS (GWAS-PW) analysis, we identified 11 pleiotropic regions between migraine and T2D and 5 pleiotropic regions between headache and T2D. Cross-trait SNP meta-analysis identified 23 novel SNP loci (Pmeta < 5 × 10−8) associated with migraine and T2D, and three novel SNP loci associated with headache and T2D. Cross-trait gene-based overlap analysis identified 33 genes significantly associated (Pgene-based < 3.85 × 10−6) with migraine and T2D, and 11 genes associated with headache and T2D, with 7 genes (EHMT2, SLC44A4, PLEKHA1, CFDP1, TMEM170A, CHST6, and BCAR1) common between them. There was also a significant overlap of genes nominally associated (Pgene-based < 0.05) with both migraine and T2D (Pbinomial-test = 2.83 × 10−46) and headache and T2D (Pbinomial-test = 4.08 × 10−29). Mendelian randomisation (MR) analyses did not provide consistent evidence for a causal relationship between migraine and T2D. However, we found headache was causally associated (inverse-variance weighted, ORIVW = 0.90, Pivw = 7 × 10−3) with T2D. Our findings robustly confirm the comorbidity of migraine and headache with T2D, with shared genetically controlled biological mechanisms contributing to their co-occurrence, and evidence for a causal relationship between headache and T2D.

Prolonged sevoflurane exposure causes abnormal synapse development and dysregulates beta-neurexin and neuroligins in the hippocampus in neonatal rats

BACKGROUND

The underlying molecular mechanisms of the excitatory/inhibitory (E/I) imbalance induced by sevoflurane exposure to neonates remain poorly understood. This study aimed to investigate the long-term effects of prolonged sevoflurane exposure to neonatal rats during the peak period of synaptogenesis on the changes of trans-synaptic neurexin-neuroligin interactions, synaptic ultrastructure in the hippocampus and cognition.

METHODS

A total of 30 rat pups at postnatal day (P) 7 was randomly divided into two groups: the control group (exposed to 30 % oxygen balanced with nitrogen) and the sevoflurane group (exposed to 2.5 % sevoflurane plus 30 % oxygen balanced with nitrogen) for 6 h. Neurocognitive behaviors were assessed with the Open field test at P23-25 and the Morris water maze test at P26-30. The expression of β-neurexin (β-NRX), N-methyl-d-aspartate receptor 2 subunit (NR2A and NR2B), neuroligin-1 (NLG-1), neuroligin-2 (NLG-2), postsynaptic density protein-95 (PSD-95), α1-subunit of the γ-aminobutyric acid A receptor (GABAAα1) and gephyrin in the hippocampus at P30 were measured by Western blot. The ultrastructure of synapses was examined under electron microscope.

RESULTS

Prolonged sevoflurane exposure at P7 resulted in cognitive deficiency in adolescence, as well as the downregulation of β-NRX, NR2A, NR2B, NLG-1, and PSD-95, and the upregulation of GABAAα1, NLG-2, and gephyrin in the hippocampal CA3 region. Sevoflurane anesthesia also increased the number of symmetric synapses in the hippocampus.

CONCLUSIONS

Prolonged sevoflurane exposure during the brain development leads to cognitive deficiency and disproportion of excitatory/inhibitory synapses which may be caused by dysregulated expression of synaptic adhesion molecules of β-NRX and neuroligins.

Regulation of the Proliferation of Diabetic Vascular Endothelial Cells by Degrading Endothelial Cell Functional Genes with QKI-7

Background

Diabetes has emerged as one of the most serious and common chronic diseases of our times, causing life-threatening, disabling and costly complications, and reducing life expectancy. Studies have shown that cardiovascular morbidity is 1–3 times higher in diabetic patients than in normal people. There are many clinical and experimental data that prove that most of the complications of diabetes are related to atherosclerosis, which suggests that chronic hyperglycemia may induce an imbalance in the proliferation of vascular endothelial cells.

Purpose

This study aims to explore the relationship between QKI-7 and vascular endothelial cell dysfunction and lay a foundation for further clarifying the molecular mechanism of endothelial cell damage in the process of diabetes with atherosclerosis.

Methods

We chose blood samples and pluripotent stem cells and vascular endothelial cells of hospitalized patients with diabetes and diabetes atherosclerosis as research subjects. The expression levels of endothelial cell proliferation and genes related to endothelial cell proliferation were analyzed by RT-qPCR and Western blot, to study the influence of QKi-7 on the physiological state of endothelial cells. Through gene knockdown experiment, the effects of QKi-7 knockdown on functional genes and physiological functions of endothelial cells were analyzed. Finally, RNA immunoprecipitation was used to test the mutual effect among QKI-7 and the transcription level of functional genes, and the mRNA attenuation experiment proved that QKI-7 participated in the degradation process of functional genes.

Results

The findings of the RT-qPCR and Western blot tests revealed that QKI-7 was highly expressed in blood samples of diabetic patients and atherosclerosis as well as in endothelial cells induced by human pluripotent stem cells and human vascular endothelial cells after high-glucose treatment. Overexpression and high glucose of QKI-7 resulted in inhibiting expressed function genes CD144, NLGN1, and TSG6 and upregulation of inflammatory factors TNF-α, IL-1β, and IFN-γ, leading to excessive proliferation of endothelial cells. After QKI-7 gene knockdown, the expression levels of CD144, NLGN1, and TSG6, inflammatory factors TNF-α, IL-1β, and IFN-γ, and the cell proliferation rate all returned to normal levels. RNA immunoprecipitation showed that QKi-7 interacted with CD144, NLGN1, and TSG6 mRNAs and was involved in the transcriptional degradation of functional genes through their interactions.

Conclusion

This research initially revealed the relevant molecular mechanism of QKI-7 leading to the excessive proliferation of endothelial cells in diabetic and atherosclerotic patients. In view of the role of QKI-7 in diabetic vascular complications, we provided a potential target for clinical diabetes treatment strategies in the future.

Prognostic role of NLGN2 and PTGDS in medulloblastoma based on gene expression omnibus

BACKGROUND

Medulloblastoma (MB) is the most common intracranial malignant tumour in children, but genes and pathways involved in its pathogenesis are still under investigation. This study was designed to screen and identify biomarkers of MB to provide markers for clinical diagnosis and prognosis assessment.

METHODS

The data sets of GSE109401 and GSE42656 were acquired from Gene expression omnibus (GEO). Limma package in R was adopted to identify the differentially expressed genes (DEGs), and the GSE30074 data set was adopted to analyse their prognostic role. Children with MB (n=55) diagnosed in Affiliated Ezhou Central Hospital were enrolled and assigned to the patient group, and healthy children (n=30) who received physical examination in our hospital during the same time period were assigned to the control group. The two groups were compared in serum NLGN2 and PTGDS levels, and all patients were followed up for three years to understand the associations of Neuroligin 2 (NLGN2) and Prostaglandin D2 synthase (PTGDS) with the survival of patients.

RESULTS

With Limma, 247 DEGs were screened out. The LASSO-Cox regression analysis revealed that 6 genes were associated with MB prognosis, and the established model revealed a lower survival rate in the high-risk group. According to Cox regression analysis, NLGN2 and PTGDS may be independent prognostic factors of MB. Similar to the data sets, the Real time-quantitative polymerase chain reaction (RT-qPCR) assay revealed lowly-expressed NLGN2 and PTGDS levels in MB patients, and patients with lower expression of them showed a lower 3-year survival rate.

CONCLUSION

With low expression in MB cases, NLGN2 and PTGDS have high prognostic value for MB.

Assessment of parental benzo[a]pyrene exposure-induced cross-generational neurotoxicity and changes in offspring sperm DNA methylome in medaka fish

Previous studies have revealed that DNA methylation changes could serve as potential genomic markers for environmental benzo[a]pyrene (BaP) exposure and intergenerational inheritance of various physiological impairments (e.g. obesity and reproductive pathologies). As a typical aromatic hydrocarbon pollutant, direct BaP exposure has been shown to induce neurotoxicity. To unravel the inheritance mechanisms of the BaP-induced bone phenotype in freshwater medaka, we conducted whole-genome bisulfite sequencing of F1 sperm and identified 776 differentially methylated genes (DMGs). Ingenuity pathway analysis revealed that DMGs were significantly enriched in pathways associated with neuronal development and function. Therefore, it was hypothesized that parental BaP exposure (1 μg/l, 21 days) causes offspring neurotoxicity. Furthermore, the possibility for sperm methylation as an indicator for a neurotoxic phenotype was investigated. The F0 adult brains and F1 larvae were analyzed for BaP-induced direct and inherited toxicity. Acetylcholinesterase activity was significantly reduced in the larvae, together with decreased swimming velocity. Molecular analysis revealed that the marker genes associated with neuron development and growth (alpha1-tubulin, mbp, syn2a, shh, and gap43) as well as brain development (dlx2, otx2, and krox-20) were universally downregulated in the F1 larvae (3 days post-hatching). While parental BaP exposure at an environmentally relevant concentration could induce neurotoxicity in the developing larvae, the brain function of the exposed F0 adults was unaffected. This indicates that developmental neurotoxicity in larvae may result from impaired neuronal development and differentiation, causing delayed brain growth. The present study demonstrates that the possible adverse health effects of BaP in the environment are more extensive than currently understood. Thus, the possibility of multigenerational BaP toxicity should be included in environmental risk assessments.

Secreted Amyloid Precursor Protein Alpha, a Neuroprotective Protein in the Brain Has Widespread Effects on the Transcriptome and Proteome of Human Inducible Pluripotent Stem Cell-Derived Glutamatergic Neurons Related to Memory Mechanisms

Secreted amyloid precursor protein alpha (sAPPα) processed from a parent human brain protein, APP, can modulate learning and memory. It has potential for development as a therapy preventing, delaying, or even reversing Alzheimer’s disease. In this study a comprehensive analysis to understand how it affects the transcriptome and proteome of the human neuron was undertaken. Human inducible pluripotent stem cell (iPSC)-derived glutamatergic neurons in culture were exposed to 1 nM sAPPα over a time course and changes in the transcriptome and proteome were identified with RNA sequencing and Sequential Window Acquisition of All THeoretical Fragment Ion Spectra-Mass Spectrometry (SWATH-MS), respectively. A large subset (∼30%) of differentially expressed transcripts and proteins were functionally involved with the molecular biology of learning and memory, consistent with reported links of sAPPα to memory enhancement, as well as neurogenic, neurotrophic, and neuroprotective phenotypes in previous studies. Differentially regulated proteins included those encoded in previously identified Alzheimer’s risk genes, APP processing related proteins, proteins involved in synaptogenesis, neurotransmitters, receptors, synaptic vesicle proteins, cytoskeletal proteins, proteins involved in protein and organelle trafficking, and proteins important for cell signalling, transcriptional splicing, and functions of the proteasome and lysosome. We have identified a complex set of genes affected by sAPPα, which may aid further investigation into the mechanism of how this neuroprotective protein affects memory formation and how it might be used as an Alzheimer’s disease therapy.

Repeated Winning and Losing Experiences in Chronic Social Conflicts Are Linked to RNA Editing Pattern Difference

Winner-loser effects influence subsequent agonistic interactions between conspecifics. Previous winning experiences could strengthen future aggression and increase the chance of winning the next agonistic interaction, while previous losing experiences could have the opposite effect. Although the role of A-to-I RNA editing has been recently implicated in chronic social defeat stress and aggressive behavior, it remains to be further elucidated in chronic social conflicts in agonistic interactions, especially in the repeated aggression (winners) and repeated defeat (losers) resulted from these conflicts. In the current study, transcriptome-wide A-to-I RNA editing in the dorsal striatum was investigated in a mouse model of chronic social conflicts, and compared between mice repeatedly winning and losing daily agonistic interactions. Our analysis identified 622 A-to-I RNA editing sites in the mouse dorsal striatum, with 23 to be differentially edited in 22 genes, most of which had been previously associated with neurological, psychiatric, or immune disorders. Among these differential RNA editing (DRE) sites four missense variants were observed in neuroligin 2 (Nlgn2), Cdc42 guanine nucleotide exchange factor 9 (Arhgef9) BLCAP apoptosis inducing factor (Blcap), and cytoplasmic FMR1 interacting protein 2 (Cyfip2), as well as two noncoding RNA sites in small nucleolar RNA host gene 11 (Snhg11) and the maternally expressed 3 (Meg3) gene. Moreover, significant changes were observed in gene functions and pathways enriched by genes with A-to-I RNA editing in losers and especially winners compared to controls. Our results demonstrate that repeated winning and losing experiences in chronic social conflicts are linked to A-to-I RNA editing pattern difference, underlining its role in the molecular mechanism of agonistic interactions between conspecifics.

Upregulated NLGN1 predicts poor survival in colorectal cancer

Background

Neuroligin1 (NLGN1) is a main component of excitatory glutamatergic synapses complex and is important for synapse assembly and function. The clinical value of NLGN1 in colorectal cancer (CRC) is not clear.

Methods

We obtained the expression data of 1143 CRC patients from 3 independent Gene Expression Omnibus (GEO) datasets (GSE32323, GSE24551, GSE39582) and The Cancer Genome Atlas (TCGA) to make the comparison of the NLGN1 expression level between CRC tissues and matched noncancerous tissues, and to evaluate its value in predicting survival of CRC patients. At the protein level, these results were further confirmed by immunohistochemical staining of 52 CRC samples in our own centre. Finally, the function of NLGN1 was explored by gene set enrichment analysis (GSEA).

Results

Increased mRNA and protein levels of NLGN1 expression were associated with worse overall survival or recurrence-free survival in CRC patients from 2 GEO datasets, the TCGA database, and our cohort. In addition, multivariate regression analysis showed that NLGN1 was an independent poor prognostic factor of survival in patients with CRC in TCGA database (OR = 2.524, P = 0.010). Functional analysis revealed that NLGN1 was correlated with function involving the Hedgehog signaling pathway, mismatch repair process, and some material metabolism processes.

Conclusions

This study is the first to implicate and verify NLGN1 as a new poor prognostic marker for CRC.

The protective effect and potential mechanism of NRXN1 on learning and memory in ADHD rat models

The learning and memory network is highly complex and remains unclear. The hippocampus is the location of learning and memory function. Impairment of synaptic morphology and synaptic plasticity (i.e., long-term potentiation) appears to cause learning and memory deficits. Several studies have indicated the role of NRXN1 in regulating the synaptic function, but little is known on its role in learning and memory dysfunction associated with attention deficit and hyperactivity disorder (ADHD). Our results showed that overexpression and interference of NRXN1 in vivo, respectively, affected learning and memory, as was assessed by Morris water maze tests, in spontaneously hypertensive rats (SHRs) and Sprague Dawley (SD) rats. We found that SD rats performed better after methylphenidate (MPH) treatment in salvage trials. Accordingly, the change of NRXN1 led to altered synapse-related gene (PSD95, SYN1, GAP43, NLGN1) expression, further providing evidence of its role in the maintenance of synaptic plasticity. We also verified that the expression of synapse-related genes synchronously changed with NRXN1expression in the behavioral assessment. The expression of NRXN1 was confirmed to affect the expression of synapse-related genes after its interference and overexpression in the primary hippocampal neurons in vitro. These results confirmed our hypothesis that NRXN1 might nucleate an overall trans-synaptic signaling network that controls synaptic plasticity and is responsible for impairments in learning and memory in ADHD. These findings suggest a possible protective role of NRXN1 in learning and memory in ADHD. Further RNA-seq sequencing revealed significant differences in the expression of 5-hydroxytryptamine receptor (5-HT₆R), which was further verified at the cellular level, and the mechanism of NRXN1 affecting synaptic plasticity was preliminarily discussed.

Proteomics Study on the Cerebrospinal Fluid of Patients with Encephalitis

OBJECTIVE

Label-free quantitative proteomics was applied to analyze differentially expressed proteins (DEPs) in the cerebrospinal fluid (CSF) of patients with encephalitis. The database was used to screen for possible biomarkers in encephalitis, followed by validation and preliminary investigation of the role of some DEPs in the pathogenesis of encephalitis using enzyme-linked immunosorbent assay (ELISA).

METHODS

We performed label-free quantitative proteomics on 16 cerebrospinal fluid samples (EM group, encephalitis with mental and behavioral disorders patients, n = 5; NED group, encephalitis without mental and behavioral disorders patients, n = 6; N group, healthy individuals, n = 5). The extracted CSF proteins were examined by mass spectrometry and enzymatic digestion and detected using protein profiling and data analysis. Interproscan was used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the DEPs. ELISA was used to verify the changes in the levels of some DEPs in the CSF.

RESULTS

A total of 941 proteins were found to be significantly differentially expressed, including 250 upregulated DEPs and 691 downregulated DEPs. GO analysis suggested that there were six enriched functions that intersect among the EM, NED, and N groups, including synapse organization, membrane, integral component of membrane, membrane part, G-protein-coupled receptor signaling pathway, and transmembrane signaling receptor activity. KEGG analysis revealed that there were three signaling pathways that intersect among the EM, NED, and N groups, including fructose and mannose metabolism, inositol phosphate metabolism, and Jak-STAT signaling pathway. Furthermore, four downregulated encephalitis-related neurological synapse proteins were identified after screening for differentially expressed proteins, including NRXN3, NFASC, LRRC4B, and NLGN2. The result of ELISA further verified that the expression of NLGN2 and LRRC4B was obviously higher in the NED group than in the N group.

CONCLUSIONS

These findings demonstrated that NLGN2 and LRRC4B proteins were upregulated in the NED group and could be potential biomarkers for the diagnosis of encephalitis, but still needs a lot of multiomics studies to be used in clinical.

Cytogenetic and Array-CGH Characterization of a Simple Case of Reciprocal t(3;10) Translocation Reveals a Hidden Deletion at 5q12

Chromosome deletions, including band 5q12, have rarely been reported and have been associated with a wide range of clinical manifestations, such as postnatal growth retardation, intellectual disability, hyperactivity, nonspecific ocular defects, facial dysmorphism, and epilepsy. In this study, we describe for the first time a child with growth retardation in which we identified a balanced t(3;10) translocation by conventional cytogenetic analysis in addition to an 8.6 Mb 5q12 deletion through array-CGH. Our results show that the phenotypic abnormalities of a case that had been interpreted as "balanced" by conventional cytogenetics are mainly due to a cryptic deletion, highlighting the need for molecular investigation in subjects with an abnormal phenotype before assuming the cause is an apparently simple cytogenetic rearrangement. Finally, we identify PDE4D and PIK3R1 genes as the two major candidates responsible for the clinical features expressed in our patient.

Expression and function of circular RNAs in the mammalian brain

Mammalian brain presents extraordinary complexity reflected in the structure, function, and dynamic changes in the biological and physiological processes of development, maturity, and aging. Recent transcriptomic profiles from the brain tissues of distinct species have described a novel class of transcripts with a covalently closed-loop structure, called circular RNAs (circRNAs), which are produced by alternative back-splicing and derived from genes associated with synaptogenesis and neural activities. Brain is a tightly regulated and largely unexplored organ where circRNAs are highly enriched and expressed in the cell type-, spatiotemporal-specific, sex-biased, and age-related manner. Although the biological functions of most of the circRNAs in the brain remain elusive, increased evidence suggests that dynamic changes in circRNA expression are critical for brain function and the maintenance of physiological homeostasis in the brain. Here, we review the latest immense progresses in the understanding of circRNA expression and function in the mammalian brain. We also discuss possibly biological functions of circRNAs in the brain, which may provide new sights of understanding brain development and aging, as well as the pathogenesis of mental diseases.

Consequences of space radiation on the brain and cardiovascular system

Staying longer in outer space will inevitably increase the health risks of astronauts due to the exposures to galactic cosmic rays and solar particle events. Exposure may pose a significant hazard to space flight crews not only during the mission but also later, when slow-developing adverse effects could finally become apparent. The body of literature examining ground-based outcomes in response to high-energy charged-particle radiation suggests differential effects in response to different particles and energies. Numerous animal and cellular models have repeatedly demonstrated the negative effects of high-energy charged-particle on the brain and cognitive function. However, research on the role of space radiation in potentiating cardiovascular dysfunction is still in its early stages. This review summarizes the available data from studies using ground-based animal models to evaluate the response of the brain and heart to the high-energy charged particles of GCR and SPE, addresses potential sex differences in these effects, and aims to highlight gaps in the current literature for future study.

SPARCL1 Promotes Excitatory But Not Inhibitory Synapse Formation and Function Independent of Neurexins and Neuroligins

Emerging evidence supports roles for secreted extracellular matrix proteins in boosting synaptogenesis, synaptic transmission, and synaptic plasticity. SPARCL1 (also known as Hevin), a secreted non-neuronal protein, was reported to increase synaptogenesis by simultaneously binding to presynaptic neurexin-1α and to postsynaptic neuroligin-1B, thereby catalyzing formation of trans-synaptic neurexin/neuroligin complexes. However, neurexins and neuroligins do not themselves mediate synaptogenesis, raising the question of how SPARCL1 enhances synapse formation by binding to these molecules. Moreover, it remained unclear whether SPARCL1 acts on all synapses containing neurexins and neuroligins or only on a subset of synapses, and whether it enhances synaptic transmission in addition to boosting synaptogenesis or induces silent synapses. To explore these questions, we examined the synaptic effects of SPARCL1 and their dependence on neurexins and neuroligins. Using mixed neuronal and glial cultures from neonatal mouse cortex of both sexes, we show that SPARCL1 selectively increases excitatory but not inhibitory synapse numbers, enhances excitatory but not inhibitory synaptic transmission, and augments NMDAR-mediated synaptic responses more than AMPAR-mediated synaptic responses. None of these effects were mediated by SPARCL1-binding to neurexins or neuroligins. Neurons from triple neurexin-1/2/3 or from quadruple neuroligin-1/2/3/4 conditional KO mice that lacked all neurexins or all neuroligins were fully responsive to SPARCL1. Together, our results reveal that SPARCL1 selectively boosts excitatory but not inhibitory synaptogenesis and synaptic transmission by a novel mechanism that is independent of neurexins and neuroligins.SIGNIFICANCE STATEMENT Emerging evidence supports roles for extracellular matrix proteins in boosting synapse formation and function. Previous studies demonstrated that SPARCL1, a secreted non-neuronal protein, promotes synapse formation in rodent and human neurons. However, it remained unclear whether SPARCL1 acts on all or on only a subset of synapses, induces functional or largely inactive synapses, and generates synapses by bridging presynaptic neurexins and postsynaptic neuroligins. Here, we report that SPARCL1 selectively induces excitatory synapses, increases their efficacy, and enhances their NMDAR content. Moreover, using rigorous genetic manipulations, we show that SPARCL1 does not require neurexins and neuroligins for its activity. Thus, SPARCL1 selectively boosts excitatory synaptogenesis and synaptic transmission by a novel mechanism that is independent of neurexins and neuroligins.

Enhancement of Drug Seeking Following Drug Taking in a Sexual Context Requires Anterior Cingulate Cortex Activity in Male Rats

Individual variance in vulnerability to develop addictions is influenced by social factors. Specifically, drug-taking in a sexual context appears to enhance further drug-seeking behavior in human users, as these users identify the effects of drugs to enhance sexual pleasure as a primary reason for continued drug use. Methamphetamine (Meth) is commonly used in this context. Similarly, male rats that self-administered Meth immediately followed by sexual behavior display enhanced drug-seeking behavior, including attenuation of extinction and increased reinstatement to seeking of Meth-associated cues. Hence, drug-taking in a sexual context enhances vulnerability for addiction. However, the neural mechanisms by which this occurs are unknown. Here the hypothesis was tested that medial prefrontal cortex is essential for this effect of Meth and sex when experienced concurrently. First it was shown that CaMKII neurons in the anterior cingulate area (ACA) were co-activated by both Meth and sex. Next, chemogenetic inactivation of ACA CaMKII cells using AAV5-CaMKIIa-hM4Di-mCherry was shown not to affect Meth-induced locomotor activity or sexual behavior. Subsequently, chemogenetic inactivation of ACA CaMKII neurons during Meth self-administration followed by sexual behavior was shown to prevent the effects of Meth and sex on enhanced reinstatement of Meth-seeking but did not affect enhanced drug-seeking during extinction tests. These results indicate that ACA CaMKII cell activation during exposure to Meth in a sexual context plays an essential role in the subsequent enhancement of drug-seeking during reinstatement tests.

Genome-wide, integrative analysis of circular RNA dysregulation and the corresponding circular RNA-microRNA-mRNA regulatory axes in autism

Circular RNAs (circRNAs), a class of long noncoding RNAs, are known to be enriched in mammalian neural tissues. Although a wide range of dysregulation of gene expression in autism spectrum disorder (ASD) have been reported, the role of circRNAs in ASD remains largely unknown. Here, we performed genome-wide circRNA expression profiling in postmortem brains from individuals with ASD and controls and identified 60 circRNAs and three coregulated modules that were perturbed in ASD. By integrating circRNA, microRNA, and mRNA dysregulation data derived from the same cortex samples, we identified 8170 ASD-associated circRNA-microRNA-mRNA interactions. Putative targets of the axes were enriched for ASD risk genes and genes encoding inhibitory postsynaptic density (PSD) proteins, but not for genes implicated in monogenetic forms of other brain disorders or genes encoding excitatory PSD proteins. This reflects the previous observation that ASD-derived organoids show overproduction of inhibitory neurons. We further confirmed that some ASD risk genes (NLGN1, STAG1, HSD11B1, VIP, and UBA6) were regulated by an up-regulated circRNA (circARID1A) via sponging a down-regulated microRNA (miR-204-3p) in human neuronal cells. Particularly, alteration of NLGN1 expression is known to affect the dynamic processes of memory consolidation and strengthening. To the best of our knowledge, this is the first systems-level view of circRNA regulatory networks in ASD cortex samples. We provided a rich set of ASD-associated circRNA candidates and the corresponding circRNA-microRNA-mRNA axes, particularly those involving ASD risk genes. Our findings thus support a role for circRNA dysregulation and the corresponding circRNA-microRNA-mRNA axes in ASD pathophysiology.

Genomic analyses reveal distinct genetic architectures and selective pressures in buffaloes

BACKGROUND

The domestic buffalo (Bubalus bubalis) is an essential farm animal in tropical and subtropical regions, whose genomic diversity is yet to be fully discovered.

RESULTS

In this study, we describe the demographic events and selective pressures of buffalo by analyzing 121 whole genomes (98 newly reported) from 25 swamp and river buffalo breeds. Both uniparental and biparental markers were investigated to provide the final scenario. The ancestors of swamp and river buffalo diverged ∼0.23 million years ago and then experienced independent demographic histories. They were domesticated in different regions, the swamp buffalo at the border between southwest China and southeast Asia, while the river buffalo in south Asia. The domestic stocks migrated to other regions and further differentiated, as testified by (at least) 2 ancestral components identified in each subspecies. Different signals of selective pressures were also detected in these 2 types of buffalo. The swamp buffalo, historically used as a draft animal, shows selection signatures in genes associated with the nervous system, while in river dairy breeds, genes under selection are related to heat stress and immunity.

CONCLUSIONS

Our findings substantially expand the catalogue of genetic variants in buffalo and reveal new insights into the evolutionary history and distinct selective pressures in river and swamp buffalo.

MicroRNA-186-5p controls GluA2 surface expression and synaptic scaling in hippocampal neurons

Homeostatic synaptic scaling is a negative feedback response to fluctuations in synaptic strength induced by developmental or learning-related processes, which maintains neuronal activity stable. Although several components of the synaptic scaling apparatus have been characterized, the intrinsic regulatory mechanisms promoting scaling remain largely unknown. MicroRNAs may contribute to posttranscriptional control of mRNAs implicated in different stages of synaptic scaling, but their role in these mechanisms is still undervalued. Here, we report that chronic blockade of glutamate receptors of the AMPA and NMDA types in hippocampal neurons in culture induces changes in the neuronal mRNA and miRNA transcriptomes, leading to synaptic upscaling. Specifically, we show that synaptic activity blockade persistently down-regulates miR-186-5p. Moreover, we describe a conserved miR-186-5p-binding site within the 3'UTR of the mRNA encoding the AMPA receptor GluA2 subunit, and demonstrate that GluA2 is a direct target of miR-186-5p. Overexpression of miR-186 decreased GluA2 surface levels, increased synaptic expression of GluA2-lacking AMPA receptors, and blocked synaptic scaling, whereas inhibition of miR-186-5p increased GluA2 surface levels and the amplitude and frequency of AMPA receptor-mediated currents, and mimicked excitatory synaptic scaling induced by synaptic inactivity. Our findings elucidate an activity-dependent miRNA-mediated mechanism for regulation of AMPA receptor expression.

Genome-wide association study of the level of blood components in Pekin ducks

Blood components are considered to reflect nutrient metabolism and immune activity in both humans and animals. In this study, we measured 12 blood components in Pekin ducks and performed genome-wide association analysis to identify the QTLs (quantitative trait locus) using a genotyping-by-sequencing strategy. A total of 54 QTLs were identified for blood components. One genome-wide significant QTL for alkaline phosphatase was identified within the intron-region of the OTOG gene (P = 1.31E-07). Moreover, 21 genome-wide significant SNPs for the level of serum cholinesterase were identified on six different scaffolds. In addition, for serum calcium, one genome-wide significant QTL was identified in the upstream region of gene RAB11B. These results provide new markers for functional studies in Pekin ducks, and several candidate genes were identified, which may provide additional insights into specific mechanisms for blood metabolism in ducks and their potential application for duck breeding programs.

Adeno-associated viral overexpression of neuroligin 2 in the mouse hippocampus enhances GABAergic synapses and impairs hippocampal-dependent behaviors

The cell adhesion molecule neuroligin2 (NLGN2) regulates GABAergic synapse development, but its role in neural circuit function in the adult hippocampus is unclear. We investigated GABAergic synapses and hippocampus-dependent behaviors following viral-vector-mediated overexpression of NLGN2. Transducing hippocampal neurons with AAV-NLGN2 increased neuronal expression of NLGN2 and membrane localization of GABAergic postsynaptic proteins gephyrin and GABA_ARγ2, and presynaptic vesicular GABA transporter protein (VGAT) suggesting trans-synaptic enhancement of GABAergic synapses. In contrast, glutamatergic postsynaptic density protein-95 (PSD-95) and presynaptic vesicular glutamate transporter (VGLUT) protein were unaltered. Moreover, AAV-NLGN2 significantly increased parvalbumin immunoreactive (PV⁺) synaptic boutons co-localized with postsynaptic gephyrin⁺ puncta. Furthermore, these changes were demonstrated to lead to cognitive impairments as shown in a battery of hippocampal-dependent mnemonic tasks and social behaviors.

Molecular Mechanisms of Synaptic Specificity: Spotlight on Hippocampal and Cerebellar Synapse Organizers

Synapses and neural circuits form with exquisite specificity during brain development to allow the precise and appropriate flow of neural information. Although this property of synapses and neural circuits has been extensively investigated for more than a century, molecular mechanisms underlying this property are only recently being unveiled. Recent studies highlight several classes of cell-surface proteins as organizing hubs in building structural and functional architectures of specific synapses and neural circuits. In the present mini-review, we discuss recent findings on various synapse organizers that confer the distinct properties of specific synapse types and neural circuit architectures in mammalian brains, with a particular focus on the hippocampus and cerebellum.