@article {2291, title = {knockout in excitatory neurons impairs postnatal synapse maturation and increases the repressive histone modification H3K27me3.}, journal = {Elife}, volume = {11}, year = {2022}, month = {2022 May 23}, abstract = {

Two epigenetic pathways of transcriptional repression, DNA methylation and polycomb repressive complex 2 (PRC2), are known to regulate neuronal development and function. However, their respective contributions to brain maturation are unknown. We found that conditional loss of the de novo DNA methyltransferase in mouse excitatory neurons altered expression of synapse-related genes, stunted synapse maturation, and impaired working memory and social interest. At the genomic level, loss of abolished postnatal accumulation of CG and non-CG DNA methylation, leaving adult neurons with an unmethylated, fetal-like epigenomic pattern at ~222,000 genomic regions. The PRC2-associated histone modification, H3K27me3, increased at many of these sites. Our data support a dynamic interaction between two fundamental modes of epigenetic repression during postnatal maturation of excitatory neurons, which together confer robustness on neuronal regulation.

}, keywords = {Animals, Brain, Disease Models, Animal, DNA Methyltransferase 3A, Histone Code, Histones, Mice, Mice, Knockout, Neurons, Polycomb Repressive Complex 2, Synapses}, issn = {2050-084X}, doi = {10.7554/eLife.66909}, author = {Li, Junhao and Pinto-Duarte, Ant{\'o}nio and Zander, Mark and Cuoco, Michael S and Lai, Chi-Yu and Osteen, Julia and Fang, Linjing and Luo, Chongyuan and Lucero, Jacinta D and Gomez-Castanon, Rosa and Nery, Joseph R and Silva-Garcia, Isai and Pang, Yan and Sejnowski, Terrence J and Powell, Susan B and Ecker, Joseph R and Mukamel, Eran A and Behrens, M Margarita} } @article {1684, title = {Evidence for opposing roles of Celsr3 and Vangl2 in glutamatergic synapse formation.}, journal = {Proc Natl Acad Sci U S A}, volume = {114}, year = {2017}, month = {2017 01 24}, pages = {E610-E618}, abstract = {

The signaling mechanisms that choreograph the assembly of the highly asymmetric pre- and postsynaptic structures are still poorly defined. Using synaptosome fractionation, immunostaining, and coimmunoprecipitation, we found that Celsr3 and Vangl2, core components of the planar cell polarity (PCP) pathway, are localized at developing glutamatergic synapses and interact with key synaptic proteins. Pyramidal neurons from the hippocampus of Celsr3 knockout mice exhibit loss of \~{}50\% of glutamatergic synapses, but not inhibitory synapses, in culture. Wnts are known regulators of synapse formation, and our data reveal that Wnt5a inhibits glutamatergic synapses formed via Celsr3. To avoid affecting earlier developmental processes, such as axon guidance, we conditionally knocked out Celsr3 in the hippocampus 1 week after birth. The CA1 neurons that lost Celsr3 also showed a loss of \~{}50\% of glutamatergic synapses in vivo without affecting the inhibitory synapses assessed by miniature excitatory postsynaptic current (mEPSC) and electron microscopy. These animals displayed deficits in hippocampus-dependent behaviors in adulthood, including spatial learning and memory and fear conditioning. In contrast to Celsr3 conditional knockouts, we found that the conditional knockout of Vangl2 in the hippocampus 1 week after birth led to a large increase in synaptic density, as evaluated by mEPSC frequency and spine density. PCP signaling is mediated by multiple core components with antagonizing functions. Our results document the opposing roles of Celsr3 and Vangl2 in glutamatergic synapse formation.

}, keywords = {Animals, Behavior, Animal, Cadherins, Cell Polarity, Cells, Cultured, Excitatory Postsynaptic Potentials, Glutamic Acid, Hippocampus, Locomotion, Male, Maze Learning, Mice, Knockout, Nerve Tissue Proteins, Pyramidal Cells, Receptors, Cell Surface, Synapses, Wnt-5a Protein}, issn = {1091-6490}, doi = {10.1073/pnas.1612062114}, author = {Thakar, Sonal and Wang, Liqing and Yu, Ting and Ye, Mao and Onishi, Keisuke and Scott, John and Qi, Jiaxuan and Fernandes, Catarina and Han, Xuemei and Yates, John R and Berg, Darwin K and Zou, Yimin} } @article {175, title = {Computational influence of adult neurogenesis on memory encoding.}, journal = {Neuron}, volume = {61}, year = {2009}, month = {2009 Jan 29}, pages = {187-202}, abstract = {

Adult neurogenesis in the hippocampus leads to the incorporation of thousands of new granule cells into the dentate gyrus every month, but its function remains unclear. Here, we present computational evidence that indicates that adult neurogenesis may make three separate but related contributions to memory formation. First, immature neurons introduce a degree of similarity to memories learned at the same time, a process we refer to as pattern integration. Second, the extended maturation and change in excitability of these neurons make this added similarity a time-dependent effect, supporting the possibility that temporal information is included in new hippocampal memories. Finally, our model suggests that the experience-dependent addition of neurons results in a dentate gyrus network well suited for encoding new memories in familiar contexts while treating novel contexts differently. Taken together, these results indicate that new granule cells may affect hippocampal function in several unique and previously unpredicted ways.

}, keywords = {Age Factors, Algorithms, Animals, Cell Proliferation, Computer Simulation, Dentate Gyrus, Humans, Memory, Nerve Net, Neural Pathways, Neurogenesis, Neuronal Plasticity, Neurons, Stem Cells, Synapses, Time Perception}, issn = {1097-4199}, doi = {10.1016/j.neuron.2008.11.026}, author = {Aimone, James B and Wiles, Janet and Gage, Fred H} } @article {132, title = {Embryonically expressed GABA and glutamate drive electrical activity regulating neurotransmitter specification.}, journal = {J Neurosci}, volume = {28}, year = {2008}, month = {2008 Apr 30}, pages = {4777-84}, abstract = {

Neurotransmitter signaling in the mature nervous system is well understood, but the functions of transmitters in the immature nervous system are less clear. Although transmitters released during embryogenesis regulate neuronal proliferation and migration, little is known about their role in regulating early neuronal differentiation. Here, we show that GABA and glutamate drive calcium-dependent embryonic electrical activity that regulates transmitter specification. The number of neurons expressing different transmitters changes when GABA or glutamate signaling is blocked chronically, either using morpholinos to knock down transmitter-synthetic enzymes or applying pharmacological receptor antagonists during a sensitive period of development. We find that calcium spikes are triggered by metabotropic GABA and glutamate receptors, which engage protein kinases A and C. The results reveal a novel role for embryonically expressed neurotransmitters.

}, keywords = {Animals, Antigens, CD57, Calcium, Choline O-Acetyltransferase, Embryo, Nonmammalian, Enzyme Inhibitors, Excitatory Amino Acid Antagonists, GABA Antagonists, gamma-Aminobutyric Acid, Gene Expression Regulation, Developmental, Glutamate Decarboxylase, Glutamic Acid, Health Services Research, Larva, Morpholines, Neurons, Phosphoserine, Receptors, GABA, Receptors, Glutamate, Synapses, Vesicular Glutamate Transport Proteins, Xenopus}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.4873-07.2008}, author = {Root, Cory M and Vel{\'a}zquez-Ulloa, Norma A and Monsalve, Gabriela C and Minakova, Elena and Spitzer, Nicholas C} } @article {131, title = {Activity-dependent neurotransmitter-receptor matching at the neuromuscular junction.}, journal = {Proc Natl Acad Sci U S A}, volume = {104}, year = {2007}, month = {2007 Jan 2}, pages = {335-40}, abstract = {

Signaling in the nervous system requires matching of neurotransmitter receptors with cognate neurotransmitters at synapses. The vertebrate neuromuscular junction is the best studied cholinergic synapse, but the mechanisms by which acetylcholine is matched with acetylcholine receptors are not fully understood. Because alterations in neuronal calcium spike activity alter transmitter specification in embryonic spinal neurons, we hypothesized that receptor expression in postsynaptic cells follows changes in transmitter expression to achieve this specific match. We find that embryonic vertebrate striated muscle cells normally express receptors for glutamate, GABA, and glycine as well as for acetylcholine. As maturation progresses, acetylcholine receptor expression prevails. Receptor selection is altered when early neuronal calcium-dependent activity is perturbed, and remaining receptor populations parallel changes in transmitter phenotype. In these cases, glutamatergic, GABAergic, and glycinergic synaptic currents are recorded from muscle cells, demonstrating that activity regulates matching of transmitters and their receptors in the assembly of functional synapses.

}, keywords = {Animals, Calcium, Gene Expression Regulation, Developmental, Muscle, Skeletal, Neuromuscular Junction, Neurotransmitter Agents, Receptors, Neurotransmitter, Spinal Cord, Synapses, Xenopus}, issn = {0027-8424}, doi = {10.1073/pnas.0607450104}, author = {Borodinsky, Laura N and Spitzer, Nicholas C} }