Project description:FUS is a primarily nuclear RNA-binding protein with important roles in RNA processing and transport. FUS mutations disrupting its nuclear localization characterize a subset of amyotrophic lateral sclerosis (ALS-FUS) patients, through an unidentified pathological mechanism. FUS regulates nuclear RNA, but its role at the synapse is poorly understood. Here, we used super-resolution imaging to determine the physiological localization of extranuclear, neuronal FUS and found it predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosome preparations, we identified synaptic RNA targets of FUS that are associated with synapse organization and plasticity. Synaptic FUS was significantly increased in a knock-in mouse model of ALS-FUS, at presymptomatic stages. Despite apparently unaltered synaptic organization, RNA-seq of synaptoneurosomes highlighted age-dependent dysregulation of glutamatergic and GABAergic synapses. Our study indicates that FUS relocalization to the synapse in early stages of ALS-FUS results in synaptic impairment, potentially representing an initial trigger of neurodegeneration.
Project description:FUS is a primarily nuclear RNA-binding protein with important roles in RNA processing and transport. FUS mutations disrupting its nuclear localization characterize a subset of amyotrophic lateral sclerosis (ALS-FUS) patients, through an unidentified pathological mechanism. FUS regulates nuclear RNA, but its role at the synapse is poorly understood. Here, we used super-resolution imaging to determine the physiological localization of extranuclear, neuronal FUS and found it predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosome preparations, we identified synaptic RNA targets of FUS that are associated with synapse organization and plasticity. Synaptic FUS was significantly increased in a knock-in mouse model of ALS-FUS, at presymptomatic stages. Despite apparently unaltered synaptic organization, RNA-seq of synaptoneurosomes highlighted age-dependent dysregulation of glutamatergic and GABAergic synapses. Our study indicates that FUS relocalization to the synapse in early stages of ALS-FUS results in synaptic impairment, potentially representing an initial trigger of neurodegeneration.
Project description:FUS is a primarily nuclear RNA-binding protein with important roles in RNA processing and transport. FUS mutations disrupting its nuclear localization characterize a subset of amyotrophic lateral sclerosis (ALS-FUS) patients, through an unidentified pathological mechanism. FUS regulates nuclear RNA, but its role at the synapse is poorly understood. Here, we used super-resolution imaging to determine the physiological localization of extranuclear, neuronal FUS and found it predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosome preparations, we identified synaptic RNA targets of FUS that are associated with synapse organization and plasticity. Synaptic FUS was significantly increased in a knock-in mouse model of ALS-FUS, at presymptomatic stages. Despite apparently unaltered synaptic organization, RNA-seq of synaptoneurosomes highlighted age-dependent dysregulation of glutamatergic and GABAergic synapses. Our study indicates that FUS relocalization to the synapse in early stages of ALS-FUS results in synaptic impairment, potentially representing an initial trigger of neurodegeneration.
Project description:The AMPA glutamate receptor (AMPAR) is the major type of synaptic excitatory ionotropic receptor in the brain. The most abundant AMPAR subtypes in the hippocampus are GluA1/2 and GluA2/3 heterotetramers. Each subtype contributes differentially to mechanisms of synaptic plasticity, which may be in part caused by how these receptors are regulated by specific associated proteins. A broad range of AMPAR interacting proteins have been identified and several were shown to affect biogenesis, AMPAR trafficking, and channel properties, alone or in distinct assemblies, and several revealed preferred binding to specific AMPAR subunits. To date, a systematic separate interactome analysis of the major GluA1/2 and GluA2/3 AMPAR subtypes is lacking. To reveal interactors belonging to specific AMPAR sub-complexes, we performed both quantitative and interaction proteomics on hippocampi of wildtype and GluA1- or GluA3 knock-out mice. Whereas GluA1/2 receptors co-purified TARP-γ8, PRRT1 and CNIH2 with highest abundances, GluA2/3 receptors revealed strongest co-purification of CNIH2, TARP-γ2, and OLFM1. Further analysis revealed that TARP-γ8-PRRT1 can interact directly, and co-assemble into an AMPAR subcomplex especially near the synapse.
Project description:Fast synaptic inhibition is dependent on targeting specific GABAAR subtypes to dendritic and axon initial segment (AIS) synapses. Synaptic GABAARs are typically assembled from 1-3, and subunits. Here, we isolate distinct GABAARs from the brain and interrogate their composition using quantitative proteomics. We show that α2-containing receptors co-assemble with α1 subunits, whereas α1 receptors can form GABAARs with α1 as the sole subunit. We demonstrate that α1 and α2 subunit-containing receptors co-purify with distinct spectrin isoforms; cytoskeletal proteins that link transmembrane proteins to the cytoskeleton. β2-spectrin was preferentially associated with α1-containing GABAARs at dendritic synapses, while β4-spectrin was associated with 2-containing GABAARs at AIS synapses. Ablating β2-spectrin expression reduced dendritic and AIS synapses containing α1 but increased the number of synapses containing α2, which altered phasic inhibition. Thus, we demonstrate a role for spectrins in the synapse-specific targeting of GABAARs, determining the efficacy of fast neuronal inhibition.
Project description:Alcoholism is a complex neurological disorder characterized by loss of control in limiting intake, and progressive compulsion to seek and consume ethanol. Prior studies have suggested that the characteristic behaviors associated with escalation of drug use are caused, at least in part, by ethanol-evoked changes in gene expression affecting synaptic plasticity. Implicit in this hypothesis is a dependence on new protein synthesis and remodeling at the synapse. It is well established that mRNA can be transported to neuronal distal processes, where it can undergo localized translation that is regulated in a spatially restricted manner in response to stimulation. It is unknown whether such modulation of the synaptic transcriptome might contribute to ethanol-induced synaptic plasticity. Using ethanol-induced behavioral sensitization as a model of neuroplasticity, here we investigated whether repeated exposure to ethanol altered the synaptic transcriptome, contributing to synaptic plasticity underlying a subsequent increase in the ethanol-evoked locomotor response. A synaptoneurosome preparation was utilized to enrich for RNAs trafficked to the synapse versus the proximal cellular fraction. Two complementary methods of genomic profiling, RNA-Seq and microarrays, were used to survey the synaptic transcriptome of DBA/2J mice subjected to ethanol-induced behavioral sensitization. Strikingly, a large number of genes regulated by acute ethanol showed adaptation to repeated ethanol exposure with sensitization. Genomic profiling showed distinct functional classes in RNA found to be enriched in the synaptoneurosome faction, consistent with their role in synaptic function. A subset of ethanol-responsive genes significantly enriched at the synapse were related to biological functions such as protein folding and extra-cellular matrix components, suggesting a role for local regulation of synaptic protein function by ethanol. In contrast, RNA classes regulated by ethanol in the cell soma included an over-abundance of RNA-binding and trafficking proteins, perhaps reflecting increased demand for dendritic RNA localization. These experiments document that both acute and repeated ethanol produce specific alterations in the complement of RNA at the synapse and lay the foundation for further investigations into the role of the synaptic transcriptome in behavioral adaptations to ethanol. 24 samples were analyzed from 3 treatment groups and 2 cell fractions with 4 biological replicates for each treatment/cell fraction.Cell fractionation was carried out on tissue from a frontal pole dissection of DBA2/J mice, isolating a cytosolic (S2) and synaptoneurosomal (P2) fraction. Treatment groups describe chronic treatment (10 daily injections) and treatment used on test day (single injeciion), producing saline-saline (SS), saline-ethanol (SE) and ethanol-ethanol (EE) groups. Analysis of RNA-seq compared similar treatments across cell fractions or different treatments within a cell fraction.
Project description:Information processing and storage in the brain rely on AMPA-receptors (AMPARs) and their context-dependent dynamics in synapses and extra-synaptic sites. We found that distribution and dynamics of AMPARs in the plasma membrane are controlled by Noelins, a three-member family of conserved secreted proteins expressed throughout the brain in a cell type-specific manner. Noelin tetramers tightly assemble with the extracellular domains of AMPARs and interconnect them in a network-like configuration with a variety of secreted and membrane-anchored proteins including Neurexin1, Neuritin1, and Seizure 6-like. Knockout of Noelins1-3 profoundly reduced AMPARs in synapses onto excitatory and inhibitory (inter)neurons, decreased their density and clustering in dendrites and abolished activity-dependent synaptic plasticity. Our results uncover an endogenous mechanism for extracellular anchoring of AMPARs and establish Noelin-organized networks as versatile determinants of constitutive and context-dependent neurotransmission.
Project description:Ongoing neuronal activity during development and plasticity acts to refine synaptic connections and contributes to the induction of plasticity and ultimately long term memory storage. Activity-dependent post-transcriptional control of mRNAs occurs through transport to axonal and dendritic compartments, local translation, and mRNA stability. We have identified a mechanism that contributes to activity-dependent regulation of mRNA stability during synaptic plasticity. In this study we demonstrate rapid, post-transtriptional control over process-enriched mRNAs by neuronal activity. Systematic analysis of the 3'-UTRs of destablized transcripts, identifies enrichment in sequence motifs corresponding to miRNA binding sites. The miRNAs that were identified, miR-326-3p/miR-330-5p, miR-485-5p, miR-666-3p, and miR-761 are predicted to regulate networks of genes important in plasticity and development. We find that these miRNAs are developmentally regulated in the hippocampus, many increasing by postnatal day 14. We further show that miR-485-5p controls NGF-induced neurite outgrowth in PC12 cells, tau expression, and axonal development in hippocampal neurons. miRNAs can function at the synapse to rapidly control and affect short- and long-term changes at the synapse. These processes likely occur during refinement of synaptic connections and contribute to the induction of plasticity and learning and memory. 12 hippocampal cell culture samples analysed, 3 coverslips pooled per sample. Treatments are as follows: Block: an inhibitor cocktail containing 50 µM D-APV, 40 µM CNQX, and 100 nM TTX for 3 hrs Activity: 50 µM bicuculline (BiC)/500 µM 4-Aminopyridine ActD: 25 µM actinomycin D
Project description:Ongoing neuronal activity during development and plasticity acts to refine synaptic connections and contributes to the induction of plasticity and ultimately long term memory storage. Activity-dependent post-transcriptional control of mRNAs occurs through transport to axonal and dendritic compartments, local translation, and mRNA stability. We have identified a mechanism that contributes to activity-dependent regulation of mRNA stability during synaptic plasticity. In this study we demonstrate rapid, post-transtriptional control over process-enriched mRNAs by neuronal activity. Systematic analysis of the 3'-UTRs of destablized transcripts, identifies enrichment in sequence motifs corresponding to miRNA binding sites. The miRNAs that were identified, miR-326-3p/miR-330-5p, miR-485-5p, miR-666-3p, and miR-761 are predicted to regulate networks of genes important in plasticity and development. We find that these miRNAs are developmentally regulated in the hippocampus, many increasing by postnatal day 14. We further show that miR-485-5p controls NGF-induced neurite outgrowth in PC12 cells, tau expression, and axonal development in hippocampal neurons. miRNAs can function at the synapse to rapidly control and affect short- and long-term changes at the synapse. These processes likely occur during refinement of synaptic connections and contribute to the induction of plasticity and learning and memory. 4 samples analysed, 3 coverslips pooled per sample. Mouse DRG neuron cell bodies and axons were separated in multicompartment cell cultures allowing electrical stimulation of axons, growing under a high-resistance partition between compartments, through platinum electrodes in the lid of the culture dish (Reference: http://www.ncbi.nlm.nih.gov/pubmed/9295372)
Project description:Ongoing neuronal activity during development and plasticity acts to refine synaptic connections and contributes to the induction of plasticity and ultimately long term memory storage. Activity-dependent post-transcriptional control of mRNAs occurs through transport to axonal and dendritic compartments, local translation, and mRNA stability. We have identified a mechanism that contributes to activity-dependent regulation of mRNA stability during synaptic plasticity. In this study we demonstrate rapid, post-transtriptional control over process-enriched mRNAs by neuronal activity. Systematic analysis of the 3'-UTRs of destablized transcripts, identifies enrichment in sequence motifs corresponding to miRNA binding sites. The miRNAs that were identified, miR-326-3p/miR-330-5p, miR-485-5p, miR-666-3p, and miR-761 are predicted to regulate networks of genes important in plasticity and development. We find that these miRNAs are developmentally regulated in the hippocampus, many increasing by postnatal day 14. We further show that miR-485-5p controls NGF-induced neurite outgrowth in PC12 cells, tau expression, and axonal development in hippocampal neurons. miRNAs can function at the synapse to rapidly control and affect short- and long-term changes at the synapse. These processes likely occur during refinement of synaptic connections and contribute to the induction of plasticity and learning and memory. 12 hippocampal cell culture samples analysed, 3 coverslips pooled per sample. Treatments are as follows: Block: an inhibitor cocktail containing 50 µM D-APV, 40 µM CNQX, and 100 nM TTX for 3 hrs Activity: 50 µM bicuculline (BiC)/500 µM 4-Aminopyridine ActD: 25 µM actinomycin D