Neuronally enriched microvesicle RNAs are differentially expressed in the serums of Parkinson’s patients

BackgroundCirculating small RNAs (smRNAs) originate from diverse tissues and organs. Previous studies investigating smRNAs as potential biomarkers for Parkinson’s disease (PD) have yielded inconsistent results. We investigated whether smRNA profiles from neuronally-enriched serum exosomes and microvesicles are altered in PD patients and discriminate PD subjects from controls.MethodsDemographic, clinical, and serum samples were obtained from 60 PD subjects and 40 age- and sex-matched controls. Exosomes and microvesicles were extracted and isolated using a validated neuronal membrane marker (CD171). Sequencing and bioinformatics analyses were used to identify differentially expressed smRNAs in PD and control samples. SmRNAs also were tested for association with clinical metrics. Logistic regression and random forest classification models evaluated the discriminative value of the smRNAs.ResultsIn serum CD171 enriched exosomes and microvesicles, a panel of 29 smRNAs was expressed differentially between PD and controls (false discovery rate (FDR) < 0.05). Among the smRNAs, 23 were upregulated and 6 were downregulated in PD patients. Pathway analysis revealed links to cellular proliferation regulation and signaling. Least absolute shrinkage and selection operator adjusted for the multicollinearity of these smRNAs and association tests to clinical parameters via linear regression did not yield significant results. Univariate logistic regression models showed that four smRNAs achieved an AUC ≥ 0.74 to discriminate PD subjects from controls. The random forest model had an AUC of 0.942 for the 29 smRNA panel.ConclusionCD171-enriched exosomes and microvesicles contain the differential expression of smRNAs between PD and controls. Future studies are warranted to follow up on the findings and understand the scientific and clinical relevance

Temporal Specification and Bilaterality of Human Neocortical Topographic Gene Expression

SummaryTranscriptional events involved in the development of human cerebral neocortex are poorly understood. Here, we analyzed the temporal dynamics and laterality of gene expression in human and macaque monkey neocortex. We found that interareal differences exhibit a temporal hourglass pattern, dividing the human neocortical development into three major phases. The first phase, corresponding to prenatal development, is characterized by the highest number of differential expressed genes among areas and gradient-like expression patterns, including those that are different between human and macaque. The second, preadolescent phase, is characterized by lesser interareal expression differences and by an increased synchronization of areal transcriptomes. During the third phase, from adolescence onward, differential expression among areas increases again driven predominantly by a subset of areas, without obvious gradient-like patterns. Analyses of left-right gene expression revealed population-level global symmetry throughout the fetal and postnatal time span. Thus, human neocortical topographic gene expression is temporally specified and globally symmetric

Neuroligin3 splice isoforms shape inhibitory synaptic function in the mouse hippocampus

Synapse formation is a dynamic process essential for the development and maturation of the neuronal circuitry in the brain. At the synaptic cleft, transsynaptic protein-protein interactions are major biological determinants of proper synapse efficacy. The balance of excitatory and inhibitory synaptic transmission (E-I balance) stabilizes synaptic activity, and dysregulation of the E-I balance has been implicated in neurodevelopmental disorders, including autism spectrum disorders. However, the molecular mechanisms underlying the E-I balance remain to be elucidated. Here, using single-cell transcriptomics, immunohistochemistry and electrophysiology approaches to murine CA1 pyramidal neurons obtained from organotypic hippocampal slice cultures, we investigate Neuroligin (Nlgn) genes that encode a family of postsynaptic adhesion molecules known to shape excitatory and inhibitory synaptic function. We demonstrate that the NLGN3 protein differentially regulates inhibitory synaptic transmission in a splice isoform-dependent manner at hippocampal CA1 synapses. We also found that distinct subcellular localizations of the NLGN3 isoforms contribute to the functional differences observed among these isoforms. Finally, results from single-cell RNA-Seq analyses revealed that Nlgn1 and Nlgn3 are the major murine Nlgn genes and that the expression levels of the Nlgn splice isoforms are highly diverse in CA1 pyramidal neurons. Our results delineate isoform-specific effects of Nlgn genes on the E-I balance in the murine hippocampus

Homozygosity for the SCN10A Polymorphism rs6795970 Is Associated With Hypoalgesic Inflammatory Bowel Disease Phenotype

Background: Hypoalgesic inflammatory bowel disease (IBD), a condition in which patients with active disease do not perceive and/or report abdominal pain, is associated with serious complications and there is a lack of cost-effective, reliable diagnostic methods to identify “at-risk” patients. The voltage-gated sodium channels (VGSC's), Nav1.7, Nav1.8, and Nav1.9, are preferentially expressed on nociceptive neurons, and have been implicated in visceral inflammatory pain. At least 29 VGSC single nucleotide polymorphisms (SNPs) have been implicated in chronic somatic pain syndromes, but little is known about their role in human visceral sensation. We hypothesized that disruptive VGSC polymorphisms result in anti-nociceptive behavior in IBD.Methods and Findings: We performed targeted exome sequencing and/or TaqMan genotyping to evaluate the Nav1.7, Nav1.8, and Nav1.9 genes (SCN9A, SCN10A and SCN11A) in 121 IBD patients (including 41 “hypoalgesic” IBD patients) and 86 healthy controls. Allelic and genotypic frequencies of polymorphisms were compared among study groups who had undergone characterization of intestinal inflammatory status and abdominal pain experience. Forty-nine total exonic SNPs were identified. The allelic frequency of only one non-synonymous SNP (rs6795970 [SCN10A]) approached significance in hypoalgesic IBD patients when compared to other IBD patients (p = 0.096, Fisher's exact test). Hypoalgesic IBD patients were more likely to be homozygous for this polymorphism (46 vs. 22%, p = 0.01, Fisher's exact test).Conclusions: This is the first human study to demonstrate a link between a genetic variant of SCN10A and abdominal pain perception in IBD. These findings provide key insights into visceral nociceptive physiology and new diagnostic and therapeutic targets to consider in IBD and other gastrointestinal conditions associated with chronic abdominal pain. Further studies are required to elucidate the precise pathophysiological impact of the rs6795970 polymorphism on human gastrointestinal nociception

Specific Neuroligin3-alphaNeurexin1 signaling regulates GABAergic synaptic function in mouse hippocampus

Synapse formation and regulation require signaling interactions between pre- and postsynaptic proteins, notably cell adhesion molecules (CAMs). It has been proposed that the functions of neuroligins (Nlgns), postsynaptic CAMs, rely on the formation of trans-synaptic complexes with neurexins (Nrxns), presynaptic CAMs. Nlgn3 is a unique Nlgn isoform that localizes at both excitatory and inhibitory synapses. However, Nlgn3 function mediated via Nrxn interactions is unknown. Here we demonstrate that Nlgn3 localizes at postsynaptic sites apposing vesicular glutamate transporter 3-expressing (VGT3+) inhibitory terminals and regulates VGT3+ inhibitory interneuron-mediated synaptic transmission in mouse organotypic slice cultures. Gene expression analysis of interneurons revealed that the alphaNrxn1+AS4 splice isoform is highly expressed in VGT3+ interneurons as compared with other interneurons. Most importantly, postsynaptic Nlgn3 requires presynaptic alphaNrxn1+AS4 expressed in VGT3+ interneurons to regulate inhibitory synaptic transmission. Our results indicate that specific Nlgn-Nrxn signaling generates distinct functional properties at synapses

A Specific Neuroligin3-αNeurexin1 Code Regulates GABAergic Synaptic Function in Mouse Hippocampus [preprint]

Synapse formation and regulation require interactions between pre- and postsynaptic proteins, notably cell adhesion molecules (CAMs). It has been proposed that the functions of neuroligins (Nlgns), postsynaptic CAMs, rely on the formation of trans-synaptic complexes with neurexins (Nrxns), presynaptic CAMs. Nlgn3 is a unique Nlgn isoform that localizes at both excitatory and inhibitory synapses. However, Nlgn3 function mediated via Nrxn interactions is unknown. Here, we demonstrate that Nlgn3 localizes at postsynaptic sites apposing vesicular glutamate transporter 3-expressing (VGT3+) inhibitory terminals and regulates VGT3+ inhibitory interneuron-mediated synaptic transmission in mouse organotypic slice cultures. Gene expression analysis of interneurons revealed that the αNrxn1+AS4 splice isoform is highly expressed in VGT3+ interneurons as compared with other interneurons. Most importantly, postsynaptic Nlgn3 requires presynaptic αNrxn1+AS4 expressed in VGT3+ interneurons to regulate inhibitory synaptic transmission. Our results indicate that specific Nlgn-Nrxn interactions generate distinct functional properties at synapses

Transdifferentiation of Human Circulating Monocytes Into Neuronal-Like Cells in 20 Days and Without Reprograming

Despite progress, our understanding of psychiatric and neurological illnesses remains poor, at least in part due to the inability to access neurons directly from patients. Currently, there are in vitro models available but significant work remains, including the search for a less invasive, inexpensive and rapid method to obtain neuronal-like cells with the capacity to deliver reproducible results. Here, we present a new protocol to transdifferentiate human circulating monocytes into neuronal-like cells in 20 days and without the need for viral insertion or reprograming. We have thoroughly characterized these monocyte-derived-neuronal-like cells (MDNCs) through various approaches including immunofluorescence (IF), flow cytometry, qRT-PCR, single cell mRNA sequencing, electrophysiology and pharmacological techniques. These MDNCs resembled human neurons early in development, expressed a variety of neuroprogenitor and neuronal genes as well as several neuroprogenitor and neuronal proteins and also presented electrical activity. In addition, when these neuronal-like cells were exposed to either dopamine or colchicine, they responded similarly to neurons by retracting their neuronal arborizations. More importantly, MDNCs exhibited reproducible differentiation rates, arborizations and expression of dopamine 1 receptors (DR1) on separate sequential samples from the same individual. Differentiation efficiency measured by cell morphology was on average 11.9 ± 1.4% (mean, SEM, n = 38,819 cells from 15 donors). To provide context and help researchers decide which in vitro model of neuronal development is best suited to address their scientific question,we compared our results with those of other in vitro models currently available and exposed advantages and disadvantages of each paradigm

Neural stem cells direct axon guidance via their radial fiber scaffold

Neural stem cells directly or indirectly generate all neurons and macroglial cells and guide migrating neurons by using a palisade-like scaffold made of their radial fibers. Here, we describe an unexpected role for the radial fiber scaffold in directing corticospinal and other axons at the junction between the striatum and globus pallidus. The maintenance of this scaffold, and consequently axon pathfinding, is dependent on the expression of an atypical RHO-GTPase, RND3/RHOE, together with its binding partner ARHGAP35/P190A, a RHO GTPase-activating protein, in the radial glia-like neural stem cells within the ventricular zone of the medial ganglionic eminence. This role is independent of RND3 and ARHGAP35 expression in corticospinal neurons, where they regulate dendritic spine formation, axon elongation, and pontine midline crossing in a FEZF2-dependent manner. The prevalence of neural stem cell scaffolds and their expression of RND3 and ARHGAP35 suggests that these observations might be broadly relevant for axon guidance and neural circuit formation.This work was supported by Labex LifeSenses grants ANR-10-LABX-65 and ANR-11-IDEX-0004-02 to A.C.; MINECO SAF2013-49176-C2-1-R and Programa Santander-FUSP to I.P.-R. and J.T.; NIH grants R01 MH115939, NS105640, and NS089662 to A.J.K.; and NIH grants MH103339, MH106934, MH110926, and MH109904 to N.S. Additional support was provided by the Kavli Foundation and the Simons Foundation.Peer reviewe

Integrative functional genomic analysis of human brain development and neuropsychiatric risks

INTRODUCTION The brain is responsible for cognition, behavior, and much of what makes us uniquely human. The development of the brain is a highly complex process, and this process is reliant on precise regulation of molecular and cellular events grounded in the spatiotemporal regulation of the transcriptome. Disruption of this regulation can lead to neuropsychiatric disorders. RATIONALE The regulatory, epigenomic, and transcriptomic features of the human brain have not been comprehensively compiled across time, regions, or cell types. Understanding the etiology of neuropsychiatric disorders requires knowledge not just of endpoint differences between healthy and diseased brains but also of the developmental and cellular contexts in which these differences arise. Moreover, an emerging body of research indicates that many aspects of the development and physiology of the human brain are not well recapitulated in model organisms, and therefore it is necessary that neuropsychiatric disorders be understood in the broader context of the developing and adult human brain. RESULTS Here we describe the generation and analysis of a variety of genomic data modalities at the tissue and single-cell levels, including transcriptome, DNA methylation, and histone modifications across multiple brain regions ranging in age from embryonic development through adulthood. We observed a widespread transcriptomic transition beginning during late fetal development and consisting of sharply decreased regional differences. This reduction coincided with increases in the transcriptional signatures of mature neurons and the expression of genes associated with dendrite development, synapse development, and neuronal activity, all of which were temporally synchronous across neocortical areas, as well as myelination and oligodendrocytes, which were asynchronous. Moreover, genes including MEF2C, SATB2, and TCF4, with genetic associations to multiple brain-related traits and disorders, converged in a small number of modules exhibiting spatial or spatiotemporal specificity. CONCLUSION We generated and applied our dataset to document transcriptomic and epigenetic changes across human development and then related those changes to major neuropsychiatric disorders. These data allowed us to identify genes, cell types, gene coexpression modules, and spatiotemporal loci where disease risk might converge, demonstrating the utility of the dataset and providing new insights into human development and disease

Fatty acid metabolism changes in association with neurobehavioral deficits in animal models of fetal alcohol spectrum disorders

Abstract Fetal alcohol spectrum disorders (FASD) show behavioral problems due to prenatal alcohol exposure (PAE). A previous study reports changes in gene expressions linked to fatty acid (FA) metabolism in the cerebral cortex of the PAE mouse model. We find an increase of palmitic acid and arachidonic acid in phospholipid in the cerebral cortex of PAE at postnatal day 30. The increase of palmitic acid is consistent with increase of the producing enzyme, Fasn (fatty acid synthase). Decrease of 26:6 FA is also consistent with the increase of the enzyme which uses 26:6 as a substrate for making very long chain FAs, Elovl4 (elongation of very long chain fatty acids protein 4). However, there is no increase in the elongated products. Rather, lipid droplets (LDs) accumulated in the brain. Although FA-associated metabolic measurements are not affected by PAE, the abundance of FA-related gut microbiota is altered. This suggests that the gut microbiome could serve as a tool to facilitate uncovering the brain pathophysiology of FASD and a potential target to mitigate neurobehavioral problems