Project description:Cells, in particular neurons, have the capacity to adapt to environmental stimuli, a phenomenon termed cellular plasticity. The underlying processes are controlled by a network of RNA-binding proteins (RBPs). Their impact on cellular plasticity, however, is largely unknown. To address this important question, we chose Pumilio2 (Pum2) and Staufen2 (Stau2) that both regulate synaptic transmission. Surprisingly, even though both RBPs dynamically interact with each other in neurons, their respective impact on the transcriptome and proteome is highly selective. While Pum2 deficiency leads to reduced translation and protein expression, Stau2 depletion preferentially impacts RNA levels and increases protein abundance. Furthermore, we show that Pum2 activates expression of key GABAergic synaptic components, e.g. the GABAA receptor scaffold protein Gephyrin. Consequently, Pum2 depletion selectively reduced the amplitude of miniature inhibitory postsynaptic currents. Together, our data clearly demonstrate that RBPs are needed to maintain proteostasis in order to control distinct signaling pathways which critically balance synaptic transmission.
Project description:Cells, in particular neurons, have the capacity to adapt to environmental stimuli, a phenomenon termed cellular plasticity. The underlying processes are controlled by a network of RNA-binding proteins (RBPs). Their impact on cellular plasticity, however, is largely unknown. To address this important question, we chose Pumilio2 (Pum2) and Staufen2 (Stau2) that both regulate synaptic transmission. Importantly, even though both RBPs dynamically interact with each other in neurons, their respective impact on the transcriptome and proteome is highly selective. While Pum2 deficiency leads to reduced translation and protein expression, Stau2 depletion preferentially impacts RNA levels and increases protein abundance. Furthermore, Pum2 activates expression of key GABAergic synaptic components, e.g. the GABAA receptor scaffold protein Gephyrin. Consequently, Pum2 depletion selectively reduced the amplitude of miniature inhibitory postsynaptic currents. Together, our data demonstrate that RBPs are needed to maintain proteostasis in order to control distinct signaling pathways which critically balance synaptic transmission.
Project description:RNA localization and local translation are important biological processes that underlie establishment of body axis, cell migration and synaptic plasticity. However, it is unclear to which extent mRNA localization contributes toward local proteome and how much of protein localization is achieved via protein transport or local translation of uniformly distributed mRNAs. To address this question, we performed genome-wide analysis of the local proteome, transcriptome, and translation rates in neurites and cell bodies of neurons differentiated from mouse embryonic stem cells.
Project description:RNA localization and local translation are important biological processes that underlie establishment of body axis, cell migration and synaptic plasticity. However, it is unclear to which extent mRNA localization contributes toward local proteome and how much of protein localization is achieved via protein transport or local translation of uniformly distributed mRNAs. To address this question, we performed genome-wide analysis of the local proteome, transcriptome, and translation rates in neurites and cell bodies of neurons differentiated from mouse embryonic stem cells.
Project description:Synapse formation is a dynamic process essential for neuronal circuit development and maturation. At the synaptic cleft, trans-synaptic protein-protein interactions constitute major biological determinants of proper synapse efficacy. The balance of excitatory and inhibitory synaptic transmission (E-I balance) stabilizes synaptic activity and its dysregulation has been implicated in neurodevelopmental disorders including autism spectrum disorders. However, the molecular mechanisms underlying E-I balance remains to be elucidated. Here, we investigate Neuroligin (Nlgn) genes which encode a family of postsynaptic adhesion molecules that shape excitatory and inhibitory synaptic function. We identified that NLGN3 protein differentially regulates inhibitory synaptic transmission in a splice isoform-dependent manner in hippocampal CA1 synapses. Distinct subcellular localization patterns of NLGN3 isoforms contribute to the functional differences observed among splice variants. Finally, our single-cell sequencing analysis reveals that Nlgn1 and Nlgn3 are the major Nlgn genes and that Nlgn splice isoforms are highly diverse in CA1 pyramidal neurons.
Project description:Homeostatic plasticity, a form of synaptic plasticity, maintains the fine balance between overall excitation and inhibition in developing and mature neuronal networks. Although the synaptic mechanisms of homeostatic plasticity are well characterized, the associated transcriptional program remains poorly understood. We show that the Kleefstra syndrome-associated protein, EHMT1, plays a critical and cell-autonomous role in synaptic scaling by responding to attenuated neuronal firing or sensory drive. Chronic activity deprivation increased the amount of neuronal dimethylated H3 at lysine 9 (H3K9me2), the catalytic product of EHMT1 and an epigenetic marker for gene repression. Genetic knockdown and pharmacological blockade of EHMT1 or EHMT2 prevented the increase of H3K9me2 and synaptic scaling up. Furthermore, BDNF repression was preceded by EHMT1/2-mediated H3K9me2 deposition at the Bdnf promoter during synaptic scaling up, both in vivo or in vivo. These findings suggest that changes in chromatin state through H3K9me2 governs a repressive program to achieve synaptic scaling. 12 samples (4 conditions in biological triplicate), 3 wt, 3 wt tetradotoxin treated, 3 k.d., 3 k.d. tetradotoxin treated
Project description:Synaptic scaling is a form of homeostatic plasticity which allows neurons to reduce their action potential firing rate in response to chronic alterations in neural activity. Synaptic scaling requires profound changes in gene expression, but the relative contribution of local and cell-wide mechanisms to synaptic scaling is controversial. Here we performed a comprehensive multi-omics characterization of the somatic and process compartments of primary rat hippocampal neurons during synaptic scaling. Thereby, we uncovered highly compartment-specific and correlated changes in the neuronal transcriptome and proteome. Specifically, we identified highly compartment-specific downregulation of crucial regulators of neuronal excitability and excitatory synapse structure. Motif analysis further suggests an important role for trans-acting post-transcriptional regulators, including RNA-binding proteins and microRNAs, in the local regulation of the corresponding mRNAs. Altogether, our study indicates that compartmentalized gene expression changes are widespread in synaptic scaling and might co-exist with neuron-wide mechanism to allow synaptic computation and homeostasis.
Project description:current synapse proteomics are restricted to “average” composition of abundant synaptic proteins. Here we performed a subcellular proteomic workflow that could identify and quantify the deep proteome of synaptic vesicles purified from rat whole brain, including previously missing proteins present in a small percentage of central synapses. This synaptic vesicle proteome newly detected many proteins of physiological and pathological relevance particularly in low abundance range, thus providing a resource for future investigations on diversified synaptic functions and neuronal dysfunctions.
Raw data from 3 replicates of synaptosomes (P2') and 3 replicates of SV are deposited here. Each replicate coming from 24 fractions from a peptide fractionation step in the workflow.
Project description:Preliminary Summary: In this study, we set to specifically analyze effects of aging on differential splicing in the local synaptic proteome. To this end, we analyzed the RNA extracted from synaptosomes obtained from cerebral cortices of C57BL/6 mice of 3 weeks, 5 months and 19 months of age. Synaptosomes are artificial, membranous sacs that contain synaptic components and are generated by subcellular fractionation of homogenized or ground-up nerve tissue. We employ RNA-seq using paired long-reads to obtain comprehensive sequence information on synaptic transcripts and two different bioinformatic methods (DIEGO and LeafCutter) to quantify differential splicing. Finally, the change in the usage of the selected junctions was validated through RT-qPCR and RT-PCR using an independent set of samples.
Project description:Homeostatic plasticity, a form of synaptic plasticity, maintains the fine balance between overall excitation and inhibition in developing and mature neuronal networks. Although the synaptic mechanisms of homeostatic plasticity are well characterized, the associated transcriptional program remains poorly understood. We show that the Kleefstra syndrome-associated protein, EHMT1, plays a critical and cell-autonomous role in synaptic scaling by responding to attenuated neuronal firing or sensory drive. Chronic activity deprivation increased the amount of neuronal dimethylated H3 at lysine 9 (H3K9me2), the catalytic product of EHMT1 and an epigenetic marker for gene repression. Genetic knockdown and pharmacological blockade of EHMT1 or EHMT2 prevented the increase of H3K9me2 and synaptic scaling up. Furthermore, BDNF repression was preceded by EHMT1/2-mediated H3K9me2 deposition at the Bdnf promoter during synaptic scaling up, both in vivo or in vivo. These findings suggest that changes in chromatin state through H3K9me2 governs a repressive program to achieve synaptic scaling.