A Screening Study Identified Decitabine as an Inhibitor of Equid Herpesvirus 4 That Enhances the Innate Antiviral Response.

Equid herpesvirus 4 (EHV-4) is a common respiratory pathogen in horses. It sporadically induces abortion or neonatal death. Although its contribution in neurological disorders is not clearly demonstrated, there is a strong suspicion of its involvement. Despite preventive treatments using vaccines against EHV-1/EHV-4, the resurgence of alpha-EHV infection still constitutes an important threat to the horse industry. Yet very few studies have been conducted on the search for antiviral molecules against EHV-4. A screening of 42 antiviral compounds was performed in vitro on equine fibroblast cells infected with the EHV-4 405/76 reference strain (VR2230). The formation of cytopathic effects was monitored by real-time cell analysis (RTCA), and the viral load was quantified by quantitative PCR. Aciclovir, the most widely used antiviral against alpha-herpesviruses in vivo, does not appear to be effective against EHV-4 in vitro. Potential antiviral activities were confirmed for eight molecules (idoxuridine, vidarabine, pritelivir, cidofovir, valganciclovir, ganciclovir, aphidicolin, and decitabine). Decitabine demonstrates the highest efficacy against EHV-4 in vitro. Transcriptomic analysis revealed the up-regulation of various genes implicated in interferon (IFN) response, suggesting that decitabine triggers the immune antiviral pathway.

Fasting upregulates the monocarboxylate transporter MCT1 at the rat blood-brain barrier through PPAR δ activation.

BACKGROUND: The blood-brain barrier (BBB) is pivotal for the maintenance of brain homeostasis and it strictly regulates the cerebral transport of a wide range of endogenous compounds and drugs. While fasting is increasingly recognized as a potential therapeutic intervention in neurology and psychiatry, its impact upon the BBB has not been studied. This study was designed to assess the global impact of fasting upon the repertoire of BBB transporters. METHODS: We used a combination of in vivo and in vitro experiments to assess the response of the brain endothelium in male rats that were fed ad libitum or fasted for one to three days. Brain endothelial cells were acutely purified and transcriptionaly profiled using RNA-Seq. Isolated brain microvessels were used to assess the protein expression of selected BBB transporters through western blot. The molecular mechanisms involved in the adaptation to fasting were investigated in primary cultured rat brain endothelial cells. MCT1 activity was probed by in situ brain perfusion. RESULTS: Fasting did not change the expression of the main drug efflux ATP-binding cassette transporters or P-glycoprotein activity at the BBB but modulated a restrictive set of solute carrier transporters. These included the ketone bodies transporter MCT1, which is pivotal for the brain adaptation to fasting. Our findings in vivo suggested that PPAR δ, a major lipid sensor, was selectively activated in brain endothelial cells in response to fasting. This was confirmed in vitro where pharmacological agonists and free fatty acids selectively activated PPAR δ, resulting in the upregulation of MCT1 expression. Moreover, dosing rats with a specific PPAR δ antagonist blocked the upregulation of MCT1 expression and activity induced by fasting. CONCLUSIONS: Altogether, our study shows that fasting affects a selected set of BBB transporters which does not include the main drug efflux transporters. Moreover, we describe a previously unknown selective adaptive response of the brain vasculature to fasting which involves PPAR δ and is responsible for the up-regulation of MCT1 expression and activity. Our study opens new perspectives for the metabolic manipulation of the BBB in the healthy or diseased brain.

Y-complex nucleoporins independently contribute to nuclear pore assembly and gene regulation in neuronal progenitors.

Besides assembling nuclear pore complexes, the conduits of nuclear transport, many nucleoporins also contribute to chromatin organization and gene expression, with critical roles in development and pathologies. We previously reported that Nup133 and Seh1, two components of the Y-complex subassembly of the nuclear pore scaffold, are dispensable for mouse embryonic stem cell viability but required for their survival during neuroectodermal differentiation. Here, a transcriptomic analysis revealed that Nup133 regulates a subset of genes at early stages of neuroectodermal differentiation, including Lhx1 and Nup210l, which encodes a newly validated nucleoporin. These genes are also misregulated in Nup133ΔMid neuronal progenitors, in which nuclear pore basket assembly is impaired. However, a four-fold reduction of Nup133 levels, despite also affecting basket assembly, is not sufficient to alter Nup210l and Lhx1 expression. Finally, these two genes are also misregulated in Seh1-deficient neural progenitors, which only show a mild reduction in nuclear pore density. Together these data reveal a shared function of Y-complex nucleoporins in gene regulation during neuroectodermal differentiation, apparently independent of nuclear pore basket integrity.

In mice and humans, brain microvascular contractility matures postnatally.

Although great efforts to characterize the embryonic phase of brain microvascular system development have been made, its postnatal maturation has barely been described. Here, we compared the molecular and functional properties of brain vascular cells on postnatal day (P)5 vs. P15, via a transcriptomic analysis of purified mouse cortical microvessels (MVs) and the identification of vascular-cell-type-specific or -preferentially expressed transcripts. We found that endothelial cells (EC), vascular smooth muscle cells (VSMC) and fibroblasts (FB) follow specific molecular maturation programs over this time period. Focusing on VSMCs, we showed that the arteriolar VSMC network expands and becomes contractile resulting in a greater cerebral blood flow (CBF), with heterogenous developmental trajectories within cortical regions. Samples of the human brain cortex showed the same postnatal maturation process. Thus, the postnatal phase is a critical period during which arteriolar VSMC contractility required for vessel tone and brain perfusion is acquired and mature.

Individual differences in cocaine-induced conditioned place preference in male rats: Behavioral and transcriptomic evidence.

BACKGROUND: Substance use disorder emerges in a small proportion of drug users and has the characteristics of a chronic relapsing pathology. AIMS: Our study aimed to demonstrate and characterize the variability in the expression of the rewarding effects of cocaine in the conditioned place preference (CPP) paradigm. METHODS: A cocaine-CPP paradigm in male Sprague-Dawley rats with an extinction period of 12 days and reinstatement was conducted. A statistical model was developed to distinguish rats expressing or not a cocaine-induced place preference. RESULTS: Two groups of rats were identified: rats that did express rewarding effects (CPP expression (CPPE), score >102 s) and rats that did not (no CPP expression (nCPPE), score between -85 and 59 s). These two groups did not show significant differences in a battery of behavioral tests. To identify differentially expressed genes in the CPPE and nCPPE groups, a whole-transcriptome ribonucleic acid-sequencing analysis was performed in the nucleus accumbens (NAc) 24 h after the CPP test. Four immediate early genes (Fos, Egr2, Nr4a1, and Zbtb37) were differentially expressed in the NAc of CPPE rats after expression of CPP. Variability in cocaine-induced place preference persisted in the CPPE and nCPPE groups after the extinction and reinstatement phases. Transcriptomic differences observed after reinstatement were distinct from those observed immediately after expression of CPP. CONCLUSION: These new findings provide insights into the identification of mechanisms underlying interindividual variability in the response to cocaine's rewarding effects.

Expression Pattern of Purinergic Signaling Components in Colorectal Cancer Cells and Differential Cellular Outcomes Induced by Extracellular ATP and Adenosine.

The purine nucleotide adenosine triphosphate (ATP) is known for its fundamental role in cellular bioenergetics. However, in the last decades, different works have described emerging functions for ATP, such as that of a danger signaling molecule acting in the extracellular space on both tumor and stromal compartments. Beside its role in immune cell signaling, several studies have shown that high concentrations of extracellular ATP can directly or indirectly act on cancer cells. Accordingly, it has been reported that purinergic receptors are widely expressed in tumor cells. However, their expression pattern is often associated with contradictory cellular outcomes. In this work, we first investigated gene expression profiles through "RNA-Sequencing" (RNA Seq) technology in four colorectal cancer (CRC) cell lines (HT29, LS513, LS174T, HCT116). Our results demonstrate that CRC cells mostly express the A2B, P2X4, P2Y1, P2Y2 and P2Y11 purinergic receptors. Among these, the P2Y1 and P2Y2 coding genes are markedly overexpressed in all CRC cells compared to the HCEC-1CT normal-like colonic cells. We then explored the cellular outcomes induced by extracellular ATP and adenosine. Our results show that in terms of cell death induction extracellular ATP is consistently more active than adenosine against CRC, while neither compound affected normal-like colonic cell survival. Intriguingly, while for the P2Y2 receptor pharmacological inhibition completely abolished the rise in cytoplasmic Ca2+ observed after ATP exposure in all CRC cell lines, Ca2+ mobilization only impacted the cellular outcome for HT29. In contrast, non-selective phosphodiesterase inhibition completely abolished the effects of extracellular ATP on CRC cells, suggesting that cAMP and/or cGMP levels might determine cellular outcome. Altogether, our study provides novel insights into the characterization of purinergic signaling in CRC.

OTX2 Homeoprotein Functions in Adult Choroid Plexus.

The choroid plexus is an important blood barrier that secretes cerebrospinal fluid, which essential for embryonic brain development and adult brain homeostasis. The OTX2 homeoprotein is a transcription factor that is critical for choroid plexus development and remains highly expressed in adult choroid plexus. Through RNA sequencing analyses of constitutive and conditional knockdown adult mouse models, we reveal putative functional roles for OTX2 in adult choroid plexus function, including cell signaling and adhesion, and show that OTX2 regulates the expression of factors that are secreted into the cerebrospinal fluid, notably transthyretin. We also show that Otx2 expression impacts choroid plexus immune and stress responses, and affects splicing, leading to changes in the mRNA isoforms of proteins that are implicated in the oxidative stress response and DNA repair. Through mass spectrometry analysis of OTX2 protein partners in the choroid plexus, and in known non-cell-autonomous target regions, such as the visual cortex and subventricular zone, we identify putative targets that are involved in cell adhesion, chromatin structure, and RNA processing. Thus, OTX2 retains important roles for regulating choroid plexus function and brain homeostasis throughout life.

Type 2 diabetes is associated with impaired jejunal enteroendocrine GLP-1 cell lineage in human obesity.

OBJECTIVES: Altered enteroendocrine cell (EEC) function in obesity and type 2 diabetes is not fully understood. Understanding the transcriptional program that controls EEC differentiation is important because some EEC types harbor significant therapeutic potential for type 2 diabetes. METHODS: EEC isolation from jejunum of obese individuals with (ObD) or without (Ob) type 2 diabetes was obtained with a new method of cell sorting. EEC transcriptional profiles were established by RNA-sequencing in a first group of 14 Ob and 13 ObD individuals. EEC lineage and densities were studied in the jejunum of a second independent group of 37 Ob, 21 ObD and 22 non obese (NOb) individuals. RESULTS: The RNA seq analysis revealed a distinctive transcriptomic signature and a decreased differentiation program in isolated EEC from ObD compared to Ob individuals. In the second independent group of ObD, Ob and NOb individuals a decreased GLP-1 cell lineage and GLP-1 maturation from proglucagon, were observed in ObD compared to Ob individuals. Furthermore, jejunal density of GLP-1-positive cells was significantly reduced in ObD compared to Ob individuals. CONCLUSIONS: These results highlight that the transcriptomic signature of EEC discriminate obese subjects according to their diabetic status. Furthermore, type 2 diabetes is associated with reduced GLP-1 cell differentiation and proglucagon maturation leading to low GLP-1-cell density in human obesity. These mechanisms could account for the decrease plasma GLP-1 observed in metabolic diseases.

Distinctive Cellular and Metabolic Reprogramming in Porcine Lung Mononuclear Phagocytes Infected With Type 1 PRRSV Strains.

Porcine reproductive and respiratory syndrome (PRRS) has an extensive impact on pig production. The causative virus (PRRSV) is divided into two species, PRRSV-1 (European origin) and PRRSV-2 (North American origin). Within PRRSV-1, PRRSV-1.3 strains, such as Lena, are more pathogenic than PRRSV-1.1 strains, such as Flanders 13 (FL13). To date, the molecular interactions of PRRSV with primary lung mononuclear phagocyte (MNP) subtypes, including conventional dendritic cells types 1 (cDC1) and 2 (cDC2), monocyte-derived DCs (moDC), and pulmonary intravascular macrophages (PIM), have not been thoroughly investigated. Here, we analyze the transcriptome profiles of in vivo FL13-infected parenchymal MNP subpopulations and of in vitro FL13- and Lena-infected parenchymal MNP. The cell-specific expression profiles of in vivo sorted cells correlated with their murine counterparts (AM, cDC1, cDC2, moDC) with the exception of PIM. Both in vivo and in vitro, FL13 infection altered the expression of a low number of host genes, and in vitro infection with Lena confirmed the higher ability of this strain to modulate host response. Machine learning (ML) and gene set enrichment analysis (GSEA) unraveled additional relevant genes and pathways modulated by FL13 infection that were not identified by conventional analyses. GSEA increased the cellular pathways enriched in the FL13 data set, but ML allowed a more complete comprehension of functional profiles during FL13 in vitro infection. Data indicates that cellular reprogramming differs upon Lena and FL13 infection and that the latter might keep antiviral and inflammatory macrophage/DC functions silent. Although the slow replication kinetics of FL13 likely contribute to differences in cellular gene expression, the data suggest distinct mechanisms of interaction of the two viruses with the innate immune system during early infection.

Local Translation in Perisynaptic Astrocytic Processes Is Specific and Changes after Fear Conditioning.

Local translation is a conserved mechanism conferring cells the ability to quickly respond to local stimuli. In the brain, it has been recently reported in astrocytes, whose fine processes contact blood vessels and synapses. Yet the specificity and regulation of astrocyte local translation remain unknown. We study hippocampal perisynaptic astrocytic processes (PAPs) and show that they contain the machinery for translation. Using a refined immunoprecipitation technique, we characterize the entire pool of ribosome-bound mRNAs in PAPs and compare it with the one expressed in the whole astrocyte. We find that a specific pool of mRNAs is highly polarized at the synaptic interface. These transcripts encode an unexpected molecular repertoire, composed of proteins involved in iron homeostasis, translation, cell cycle, and cytoskeleton. Remarkably, we observe alterations in global RNA distribution and ribosome-bound status of some PAP-enriched transcripts after fear conditioning, indicating the role of astrocytic local translation in memory and learning.

Lipid markers and related transcripts during excitotoxic neurodegeneration in kainate-treated mice.

Lipid homeostasis is dysregulated in some neurodegenerative diseases and after brain injuries due to excess glutamate or lack of oxygen. However the kinetics and cell specificity of dysregulation in different groups of lipids during excitotoxic neuronal death are not clear. Here we examined the changes during excitotoxic neuronal death induced by injecting kainic acid (KA) into the CA1 region of mouse hippocampus. We compared neuronal loss and glial cell proliferation with changes in lipid-related transcripts and markers for different lipid groups, over 12 days after KA-treatment. As neurons showed initial signs of damage, transcripts and proteins linked to fatty acid oxidation were up-regulated. Cholesterol biosynthesis induced by transcripts controlled by the transcription factor Srebp2 seems to be responsible for a transient increase in neuronal free cholesterol at 1 to 2 days. In microglia, but not in neurons, Perilipin-2 associated lipid droplets were induced and properties of Nile red emissions suggest lipid contents change over time. After microglial expression of phagocytotic markers at 2 days, some neutral lipid deposits co-localized with lysosome markers of microglia and were detected within putative phagocytotic cups. These data delineate distinct lipid signals in neurons and glial cells during excitotoxic processes from initial neuronal damage to engagement of the lysosome-phagosome system.

Non-cell Autonomous OTX2 Homeoprotein Regulates Visual Cortex Plasticity Through Gadd45b/g.

The non-cell autonomous transfer of OTX2 homeoprotein transcription factor into juvenile mouse cerebral cortex regulates parvalbumin interneuron maturation and critical period timing. By analyzing gene expression in primary visual cortex of wild-type and Otx2+/GFP mice at plastic and nonplastic ages, we identified several putative genes implicated in Otx2-dependent visual cortex plasticity for ocular dominance. Cortical OTX2 infusion in juvenile mice induced Gadd45b/g expression through direct regulation of transcription. Intriguingly, a reverse effect was found in the adult, where reducing cortical OTX2 resulted in Gadd45b/g upregulation. Viral expression of Gadd45b in adult visual cortex directly induced ocular dominance plasticity with concomitant changes in MeCP2 foci within parvalbumin interneurons and in methylation states of several plasticity gene promoters, suggesting epigenetic regulation. This interaction provides a molecular mechanism for OTX2 to trigger critical period plasticity yet suppress adult plasticity.

Comparative Transcriptomics Highlights New Features of the Iron Starvation Response in the Human Pathogen Candida glabrata.

In this work, we used comparative transcriptomics to identify regulatory outliers (ROs) in the human pathogen Candida glabrata. ROs are genes that have very different expression patterns compared to their orthologs in other species. From comparative transcriptome analyses of the response of eight yeast species to toxic doses of selenite, a pleiotropic stress inducer, we identified 38 ROs in C. glabrata. Using transcriptome analyses of C. glabrata response to five different stresses, we pointed out five ROs which were more particularly responsive to iron starvation, a process which is very important for C. glabrata virulence. Global chromatin Immunoprecipitation and gene profiling analyses showed that four of these genes are actually new targets of the iron starvation responsive Aft2 transcription factor in C. glabrata. Two of them (HBS1 and DOM34b) are required for C. glabrata optimal growth in iron limited conditions. In S. cerevisiae, the orthologs of these two genes are involved in ribosome rescue by the NO GO decay (NGD) pathway. Hence, our results suggest a specific contribution of NGD co-factors to the C. glabrata adaptation to iron starvation.

Microglial phenotypes in the human epileptic temporal lobe.

Microglia, the immune cells of the brain, are highly plastic and possess multiple functional phenotypes. Differences in phenotype in different regions and different states of epileptic human brain have been little studied. Here we use transcriptomics, anatomy, imaging of living cells and ELISA measurements of cytokine release to examine microglia from patients with temporal lobe epilepsies. Two distinct microglial phenotypes were explored. First we asked how microglial phenotype differs between regions of high and low neuronal loss in the same brain. Second, we asked how microglial phenotype is changed by a recent seizure. In sclerotic areas with few neurons, microglia have an amoeboid rather than ramified shape, express activation markers and respond faster to purinergic stimuli. The repairing interleukin, IL-10, regulates the basal phenotype of microglia in the CA1 and CA3 regions with neuronal loss and gliosis. To understand changes in phenotype induced by a seizure, we estimated the delay from the last seizure until tissue collection from changes in reads for immediate early gene transcripts. Pseudotime ordering of these data was validated by comparison with results from kainate-treated mice. It revealed a local and transient phenotype in which microglia secrete the human interleukin CXCL8, IL-1B and other cytokines. This secretory response is mediated in part via the NRLP3 inflammasome.

Aozan: an automated post-sequencing data-processing pipeline.

MOTIVATION: Data management and quality control of output from Illumina sequencers is a disk space- and time-consuming task. Thus, we developed Aozan to automatically handle data transfer, demultiplexing, conversion and quality control once a run has finished. This software greatly improves run data management and the monitoring of run statistics via automatic emails and HTML web reports. AVAILABILITY AND IMPLEMENTATION: Aozan is implemented in Java and Python, supported on Linux systems, and distributed under the GPLv3 License at: http://www.outils.genomique.biologie.ens.fr/aozan/ . Aozan source code is available on GitHub: https://github.com/GenomicParisCentre/aozan . CONTACT: aozan@biologie.ens.fr.

Physiological adjustments and transcriptome reprogramming are involved in the acclimation to salinity gradients in diatoms.

Salinity regimes in estuaries and coastal areas vary with river discharge patterns, seawater evaporation, the morphology of the coastal waterways and the dynamics of marine water mixing. Therefore, microalgae have to respond to salinity variations at time scales ranging from daily to annual cycles. Microalgae may also have to adapt to physical alterations that induce the loss of connectivity between habitats and the enclosure of bodies of water. Here, we integrated physiological assays and measurements of morphological plasticity with a functional genomics approach to examine the regulatory changes that occur during the acclimation to salinity in the estuarine diatom Thalassiosira weissflogii. We found that cells exposed to different salinity regimes for a short or long period presented adjustments in their carbon fractions, silicon pools, pigment concentrations and/or photosynthetic parameters. Salinity-induced alterations in frustule symmetry were observed only in the long-term (LT) cultures. Whole transcriptome analyses revealed a down-regulation of nuclear and plastid encoded genes during the LT response and identified only a few regulated genes that were in common between the ST and LT responses. We propose that in diatoms, one strategy for acclimating to salinity gradients and maintaining optimal cellular fitness could be a reduction in the cost of transcription.

Immune quiescence of the brain is set by astroglial connexin 43.

In the normal brain, immune cell trafficking and immune responses are strictly controlled and limited. This unique homeostatic equilibrium, also called brain immune quiescence, is crucial to maintaining proper brain functions and is altered in various pathological processes, from chronic immunopathological disorders to cognitive and psychiatric impairments. To date, the precise nature of factors regulating the brain/immune system interrelationship is poorly understood. In the present study, we demonstrate that one of these regulating factors is Connexin 43 (Cx43), a gap junction protein highly expressed by astrocytes at the blood-brain barrier (BBB) interface. We show that, by setting the activated state of cerebral endothelium, astroglial Cx43 controls immune recruitment as well as antigen presentation mechanisms in the mouse brain. Consequently, in the absence of astroglial Cx43, recruited immune cells elaborate a specific humoral autoimmune response against the von Willebrand factor A domain-containing protein 5a, an extracellular matrix protein of the brain. Altogether, our results demonstrate that Cx43 is a new astroglial factor promoting the immune quiescence of the brain.

The Sarcoglycan complex is expressed in the cerebrovascular system and is specifically regulated by astroglial Cx30 channels.

Astrocytes, the most prominent glial cell type in the brain, send specialized processes called endfeet, around blood vessels and express a large molecular repertoire regulating the cerebrovascular system physiology. One of the most striking properties of astrocyte endfeet is their enrichment in gap junction proteins Connexin 43 and 30 (Cx43 and Cx30) allowing in particular for direct intercellular trafficking of ions and small signaling molecules through perivascular astroglial networks. In this study, we addressed the specific role of Cx30 at the gliovascular interface. Using an inactivation mouse model for Cx30 (Cx30(Δ/Δ); Δ means deleted allele) we showed that absence of Cx30 does not affect blood-brain barrier (BBB) organization and permeability. However, it results in the cerebrovascular fraction, in a strong upregulation of Sgcg encoding γ-Sarcoglycan (γ-SG), a member of the Dystrophin-associated protein complex (DAPC) connecting cytoskeleton and the extracellular matrix. The same molecular event occurs in Cx30(T5M/T5M) mutated mice, where Cx30 channels are closed, demonstrating that Sgcg regulation relied on Cx30 channel functions. We further characterized the expression of other Sarcoglycan complex (SGC) molecules in the cerebrovascular system and showed the presence of α-, ß-, δ-, γ-, ε- and ζ- SG, as well as Sarcospan. Their expression was however not modified in Cx30(Δ/Δ). These results suggest that a full SGC might be present in the cerebrovascular system, and that expression of one of its member, γ-SG, depends on Cx30 channels. As described in skeletal muscles, the SGC may contribute to membrane stabilization and signal transduction in the cerebrovascular system, which may therefore be regulated by Cx30 channel-mediated functions.

Eoulsan: a cloud computing-based framework facilitating high throughput sequencing analyses.

UNLABELLED: We developed a modular and scalable framework called Eoulsan, based on the Hadoop implementation of the MapReduce algorithm dedicated to high-throughput sequencing data analysis. Eoulsan allows users to easily set up a cloud computing cluster and automate the analysis of several samples at once using various software solutions available. Our tests with Amazon Web Services demonstrated that the computation cost is linear with the number of instances booked as is the running time with the increasing amounts of data. AVAILABILITY AND IMPLEMENTATION: Eoulsan is implemented in Java, supported on Linux systems and distributed under the LGPL License at: http://transcriptome.ens.fr/eoulsan/

A long nuclear-retained non-coding RNA regulates synaptogenesis by modulating gene expression.

A growing number of long nuclear-retained non-coding RNAs (ncRNAs) have recently been described. However, few functions have been elucidated for these ncRNAs. Here, we have characterized the function of one such ncRNA, identified as metastasis-associated lung adenocarcinoma transcript 1 (Malat1). Malat1 RNA is expressed in numerous tissues and is highly abundant in neurons. It is enriched in nuclear speckles only when RNA polymerase II-dependent transcription is active. Knock-down studies revealed that Malat1 modulates the recruitment of SR family pre-mRNA-splicing factors to the transcription site of a transgene array. DNA microarray analysis in Malat1-depleted neuroblastoma cells indicates that Malat1 controls the expression of genes involved not only in nuclear processes, but also in synapse function. In cultured hippocampal neurons, knock-down of Malat1 decreases synaptic density, whereas its over-expression results in a cell-autonomous increase in synaptic density. Our results suggest that Malat1 regulates synapse formation by modulating the expression of genes involved in synapse formation and/or maintenance.