The Experts below are selected from a list of 20787 Experts worldwide ranked by ideXlab platform
Katsuhiko Ono - One of the best experts on this subject based on the ideXlab platform.
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species specific mechanisms of Neuron subtype specification reveal evolutionary plasticity of amniote brain development
Cell Reports, 2018Co-Authors: Tadashi Nomura, Hitoshi Gotoh, Wataru Yamashita, Katsuhiko OnoAbstract:Summary Highly ordered brain architectures in vertebrates consist of Multiple Neuron subtypes with specific Neuronal connections. However, the origin of and evolutionary changes in Neuron specification mechanisms remain unclear. Here, we report that regulatory mechanisms of Neuron subtype specification are divergent in developing amniote brains. In the mammalian neocortex, the transcription factors (TFs) Ctip2 and Satb2 are differentially expressed in layer-specific Neurons. In contrast, these TFs are co-localized in reptilian and avian dorsal pallial Neurons. Multi-potential progenitors that produce distinct Neuronal subtypes commonly exist in the reptilian and avian dorsal pallium, whereas a cis -regulatory element of avian Ctip2 exhibits attenuated transcription suppressive activity. Furthermore, the Neuronal subtypes distinguished by these TFs are not tightly associated with conserved Neuronal connections among amniotes. Our findings reveal the evolutionary plasticity of regulatory gene functions that contribute to species differences in Neuronal heterogeneity and connectivity in developing amniote brains.
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Changes in the regulation of cortical neurogenesis contribute to encephalization during amniote brain evolution
Nature communications, 2013Co-Authors: Tadashi Nomura, Hitoshi Gotoh, Katsuhiko OnoAbstract:The emergence of larger brains with large numbers of Neurons is an evolutionary innovation in mammals and birds. However, the corresponding changes in cortical developmental programmes during amniote evolution are poorly understood. Here we examine the cortical development of Madagascar ground geckos, and report unique characteristics of their reptilian cortical progenitors. The rates of proliferation and Neuronal differentiation in the gecko cortex are much lower than those in other amniotes. Notch signalling is highly activated in the gecko cortical progenitors, which provides a molecular basis for the low rate of cortical neurogenesis. Interestingly, Multiple Neuron subtypes are sequentially generated in the gecko cortex, similar to other amniotes. These results suggest that changes in the regulation of cortical neural progenitors have accelerated neurogenesis and provided encephalization in mammalian and archosaurian lineages. In addition, the temporal regulation for making cortical Neuronal subtypes has evolved in a common ancestor(s) of amniotes.
Tadashi Nomura - One of the best experts on this subject based on the ideXlab platform.
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species specific mechanisms of Neuron subtype specification reveal evolutionary plasticity of amniote brain development
Cell Reports, 2018Co-Authors: Tadashi Nomura, Hitoshi Gotoh, Wataru Yamashita, Katsuhiko OnoAbstract:Summary Highly ordered brain architectures in vertebrates consist of Multiple Neuron subtypes with specific Neuronal connections. However, the origin of and evolutionary changes in Neuron specification mechanisms remain unclear. Here, we report that regulatory mechanisms of Neuron subtype specification are divergent in developing amniote brains. In the mammalian neocortex, the transcription factors (TFs) Ctip2 and Satb2 are differentially expressed in layer-specific Neurons. In contrast, these TFs are co-localized in reptilian and avian dorsal pallial Neurons. Multi-potential progenitors that produce distinct Neuronal subtypes commonly exist in the reptilian and avian dorsal pallium, whereas a cis -regulatory element of avian Ctip2 exhibits attenuated transcription suppressive activity. Furthermore, the Neuronal subtypes distinguished by these TFs are not tightly associated with conserved Neuronal connections among amniotes. Our findings reveal the evolutionary plasticity of regulatory gene functions that contribute to species differences in Neuronal heterogeneity and connectivity in developing amniote brains.
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Changes in the regulation of cortical neurogenesis contribute to encephalization during amniote brain evolution
Nature communications, 2013Co-Authors: Tadashi Nomura, Hitoshi Gotoh, Katsuhiko OnoAbstract:The emergence of larger brains with large numbers of Neurons is an evolutionary innovation in mammals and birds. However, the corresponding changes in cortical developmental programmes during amniote evolution are poorly understood. Here we examine the cortical development of Madagascar ground geckos, and report unique characteristics of their reptilian cortical progenitors. The rates of proliferation and Neuronal differentiation in the gecko cortex are much lower than those in other amniotes. Notch signalling is highly activated in the gecko cortical progenitors, which provides a molecular basis for the low rate of cortical neurogenesis. Interestingly, Multiple Neuron subtypes are sequentially generated in the gecko cortex, similar to other amniotes. These results suggest that changes in the regulation of cortical neural progenitors have accelerated neurogenesis and provided encephalization in mammalian and archosaurian lineages. In addition, the temporal regulation for making cortical Neuronal subtypes has evolved in a common ancestor(s) of amniotes.
Tonis Timmusk - One of the best experts on this subject based on the ideXlab platform.
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brain derived neurotrophic factor expression in vivo is under the control of Neuron restrictive silencer element
Journal of Biological Chemistry, 1999Co-Authors: Kaia Palm, Tonis Timmusk, Urban Lendahl, Madis MetsisAbstract:Neuron-restrictive silencer element (NRSE) has been identified in Multiple Neuron-specific genes. This element has been shown to mediate repression of Neuronal gene transcription in nonNeuronal cells. A palindromic NRSE (NRSEBDNF) is present in the proximal region of brain-derived neurotrophic factor (BDNF) promoter II. Using in vitro binding assays, we establish that the upper half-site is largely responsible for the NRSEBDNF activity. To delineate the in vivorole of NRSE in the regulation of rat BDNF gene, promoter constructs with intact and mutated NRSEBDNF were introduced into transgenic mice. Our data show that NRSEBDNF is controlling the activity of BDNF promoters I and II in the brain, thymus, and lung,i.e. in the tissues in which the intact reporter gene and endogenous BDNF mRNAs are expressed. Mutation of NRSEBDNF did not lead to the ectopic activation of the reporter gene in any other nonneural tissues. In the brain, NRSEBDNF is involved in the repression of basal and kainic acid-induced expression from BDNF promoters I and II in Neurons. However, NRSEBDNF does not control the activity of the BDNF gene in nonNeuronal cells of brain.
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Neuronal expression of zinc finger transcription factor rest nrsf xbr gene
The Journal of Neuroscience, 1998Co-Authors: Kaia Palm, Natale Belluardo, Madis Metsis, Tonis TimmuskAbstract:The identification of a common cis-acting silencer element, a Neuron-restrictive silencer element (NRSE), in Multiple Neuron-specific genes, together with the finding that zinc finger transcription factor REST/NRSF/XBR could confer NRSE-mediated silencing in non-Neuronal cells, suggested that REST/NRSF/XBR is a master negative regulator of neurogenesis. Here we show that, although REST/NRSF/XBR expression decreases during Neuronal development, it proceeds in the adult nervous system. In situhybridization analysis revealed Neuronal expression of rat REST/NRSF/XBR mRNA in adult brain, with the highest levels in the Neurons of hippocampus, pons/medulla, and midbrain. The glutamate analog kainic acid increased REST/NRSF/XBR mRNA levels in various hippocampal and cortical Neurons in vivo, suggesting that REST/NRSF/XBR has a role in Neuronal activity-implied processes. Several alternatively spliced REST/NRSF/XBR mRNAs encoding proteins with nine, five, or four zinc finger motifs are transcribed from REST/NRSF/XBR gene. Two of these transcripts are generated by Neuron-specific splicing of a 28-bp-long exon. Rat REST/NRSF/XBR protein isoforms differ in their DNA binding specificities; however, all mediate repression in transient expression assays. Our data suggest that REST/NRSF/XBR is a negative regulator rather than a transcriptional silencer of Neuronal gene expression and counteracts with positive regulators to modulate target gene expression quantitatively in different cell types, including Neurons.
Hitoshi Gotoh - One of the best experts on this subject based on the ideXlab platform.
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species specific mechanisms of Neuron subtype specification reveal evolutionary plasticity of amniote brain development
Cell Reports, 2018Co-Authors: Tadashi Nomura, Hitoshi Gotoh, Wataru Yamashita, Katsuhiko OnoAbstract:Summary Highly ordered brain architectures in vertebrates consist of Multiple Neuron subtypes with specific Neuronal connections. However, the origin of and evolutionary changes in Neuron specification mechanisms remain unclear. Here, we report that regulatory mechanisms of Neuron subtype specification are divergent in developing amniote brains. In the mammalian neocortex, the transcription factors (TFs) Ctip2 and Satb2 are differentially expressed in layer-specific Neurons. In contrast, these TFs are co-localized in reptilian and avian dorsal pallial Neurons. Multi-potential progenitors that produce distinct Neuronal subtypes commonly exist in the reptilian and avian dorsal pallium, whereas a cis -regulatory element of avian Ctip2 exhibits attenuated transcription suppressive activity. Furthermore, the Neuronal subtypes distinguished by these TFs are not tightly associated with conserved Neuronal connections among amniotes. Our findings reveal the evolutionary plasticity of regulatory gene functions that contribute to species differences in Neuronal heterogeneity and connectivity in developing amniote brains.
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Changes in the regulation of cortical neurogenesis contribute to encephalization during amniote brain evolution
Nature communications, 2013Co-Authors: Tadashi Nomura, Hitoshi Gotoh, Katsuhiko OnoAbstract:The emergence of larger brains with large numbers of Neurons is an evolutionary innovation in mammals and birds. However, the corresponding changes in cortical developmental programmes during amniote evolution are poorly understood. Here we examine the cortical development of Madagascar ground geckos, and report unique characteristics of their reptilian cortical progenitors. The rates of proliferation and Neuronal differentiation in the gecko cortex are much lower than those in other amniotes. Notch signalling is highly activated in the gecko cortical progenitors, which provides a molecular basis for the low rate of cortical neurogenesis. Interestingly, Multiple Neuron subtypes are sequentially generated in the gecko cortex, similar to other amniotes. These results suggest that changes in the regulation of cortical neural progenitors have accelerated neurogenesis and provided encephalization in mammalian and archosaurian lineages. In addition, the temporal regulation for making cortical Neuronal subtypes has evolved in a common ancestor(s) of amniotes.
Vilas Menon - One of the best experts on this subject based on the ideXlab platform.
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generalized leaky integrate and fire models classify Multiple Neuron types
Nature Communications, 2018Co-Authors: Corinne Teeter, Ramakrishnan Iyer, Vilas Menon, Nathan W Gouwens, David Feng, Jim Berg, Aaron Szafer, Nicholas Cain, Hongkui ZengAbstract:There is a high diversity of Neuronal types in the mammalian neocortex. To facilitate construction of system models with Multiple cell types, we generate a database of point models associated with the Allen Cell Types Database. We construct a set of generalized leaky integrate-and-fire (GLIF) models of increasing complexity to reproduce the spiking behaviors of 645 recorded Neurons from 16 transgenic lines. The more complex models have an increased capacity to predict spiking behavior of hold-out stimuli. We use unsupervised methods to classify cell types, and find that high level GLIF model parameters are able to differentiate transgenic lines comparable to electrophysiological features. The more complex model parameters also have an increased ability to differentiate between transgenic lines. Thus, creating simple models is an effective dimensionality reduction technique that enables the differentiation of cell types from electrophysiological responses without the need for a priori-defined features. This database will provide a set of simplified models of Multiple cell types for the community to use in network models.
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generalized leaky integrate and fire models classify Multiple Neuron types
bioRxiv, 2017Co-Authors: Corinne Teeter, Ramakrishnan Iyer, Vilas Menon, Nathan W Gouwens, David Feng, Jim Berg, Nicholas Cain, Christof Koch, Stefan MihalasAbstract:In the mammalian neocortex, there is a high diversity of Neuronal types. To facilitate construction of system models with Multiple cell types, we generate a database of point models associated with the Allen Cell Types Database. We construct a series of generalized integrate-and-fire (GLIF) models of increasing complexity aiming to reproduce the spiking behaviors of the recorded Neurons. We test the performance of these GLIF models on data from 771 Neurons from 14 transgenic lines, with increasing model performance for more complex models. To answer how complex a model needs to be to reproduce the number of electrophysiological cell types, we perform unsupervised clustering on the parameters extracted from these models. The number of clusters is smaller for individual model types, but when combining all GLIF parameters 18 clusters are obtained, while 11 clusters are obtained using 16 electrophysiological features. Therefore, these low dimensional models have the capacity to characterize the diversity of cell types without the need for a priori defined features.