Project description:To identify genes expressed in specific developing thalamic nuclei during embryonic stages, a genetic dual labelling strategy was established to mark and isolate the cells. Transcription profiles were determined for the principal sensory thalamic populations by genome-wide analysis. We identified genes expressed in distinct thalamic nuclei with a potential function in the specification of individual sensory-modality thalamocortical connections.
Project description:Nuclei of the mammalian thalamus are aggregations of neurons with unique architectures and input-output connections, yet the molecular determinants of their organizational specificity remain unknown. By comparing expression profiles of thalamus and cerebral cortex in adult rhesus monkeys we identified transcripts that are unique to dorsal thalamus or to individual nuclei within it. Real-time quantitative polymerase chain reaction and in situ hybridization analyses confirmed the findings. Expression profiling of individual nuclei microdissected from the dorsal thalamus revealed additional subsets of nucleus-specific genes. Functional annotation using Gene Ontology (GO) vocabulary and Ingenuity Pathway analysis revealed over-representation of GO categories related to development, morphogenesis, cell-cell interactions, and extracellular matrix within the thalamus- and nucleus-specific genes-many involved in the Wnt signaling pathway. Examples included the transcription factor TCF7L2, localized exclusively to excitatory neurons, a calmodulin-binding protein PCP4, the bone extracellular matrix molecules SPP1 and SPARC, and other genes involved in axon outgrowth and cell matrix interactions. Other nucleus-specific genes such as CBLN1 are involved in synaptogenesis. The genes identified likely underlie nuclear specification, cell phenotype and connectivity during development and their maintenance in the adult thalamus. Experiment Overall Design: To determine the molecular underpinnings of nuclear specificity in the dorsal thalamus we isolated micro-punches of tissue from nucleus-specific regions and processed them for microarray analysis. Replicate samples from 5 separate dorsal thalamic nuclei were processed and compared to identify genes unique to each region. Affymetrix U133A Gene Chips were used. All of the samples were isolated from untreated adult monkey brain.
Project description:The thalamus is organized into nuclei that have distinct input and output connectivities with the cortex. While first-order (FO) nuclei – also called core nuclei – relay input from sensory organs on the body surface and project to primary sensory areas, higher-order (HO) nuclei – matrix nuclei – instead receive their driver input from the cortex and project to secondary and associative areas within cortico-thalamo-cortical loops. Input-dependent processes have been shown to play a critical role in the emergence of FO thalamic neuron identity from a ground state HO neuron identity, yet how this identity emerges during development remains unknown. Here, using single-nucleus RNA sequencing of the developing embryonic thalamus we show that FO thalamic identity emerges after HO identity, and that peripheral input is critical for the maturation of excitatory, but not inhibitory FO-type neurons. Our findings reveal that subsets of HO neurons are developmentally co-opted into FO-type neurons, providing a mechanistic framework for the diversification of thalamic neuron types during development and evolution.
Project description:The thalamus integrates sensory, motor, and associative functions via distinct nuclei, yet the developmental principles driving their specification remains unclear. Here, we generate a spatiotemporal single-cell multiomic and spatial transcriptomic atlas of the embryonic mouse thalamus, combined with barcoding-based lineage tracing. We identify two major glutamatergic lineages, sensory-related and motor-associative, each governed by different gene regulatory programs and temporal dynamics. These lineages arise from spatially and molecularly distinct progenitor domains, revealing an early segregation of functional identities. Within the sensory lineage, we resolve branching sensory trajectories leading to first-order visual and somatosensory neurons, both emerging from a shared higher-order-like state. Using in silico predictions and in vivo perturbation, we identify Sp9 as a key regulator of visual thalamic fate. Together, our findings define the molecular architecture and developmental trajectories that underpin thalamic modality specification, providing a framework to understand how functional circuits emerge in the mammalian brain.
Project description:The thalamus integrates sensory, motor, and associative functions via distinct nuclei, yet the developmental principles driving their specification remains unclear. Here, we generate a spatiotemporal single-cell multiomic and spatial transcriptomic atlas of the embryonic mouse thalamus, combined with barcoding-based lineage tracing. We identify two major glutamatergic lineages, sensory-related and motor-associative, each governed by different gene regulatory programs and temporal dynamics. These lineages arise from spatially and molecularly distinct progenitor domains, revealing an early segregation of functional identities. Within the sensory lineage, we resolve branching sensory trajectories leading to first-order visual and somatosensory neurons, both emerging from a shared higher-order-like state. Using in silico predictions and in vivo perturbation, we identify Sp9 as a key regulator of visual thalamic fate. Together, our findings define the molecular architecture and developmental trajectories that underpin thalamic modality specification, providing a framework to understand how functional circuits emerge in the mammalian brain.
Project description:The thalamus integrates sensory, motor, and associative functions via distinct nuclei, yet the developmental principles driving their specification remains unclear. Here, we generate a spatiotemporal single-cell multiomic and spatial transcriptomic atlas of the embryonic mouse thalamus, combined with barcoding-based lineage tracing. We identify two major glutamatergic lineages, sensory-related and motor-associative, each governed by different gene regulatory programs and temporal dynamics. These lineages arise from spatially and molecularly distinct progenitor domains, revealing an early segregation of functional identities. Within the sensory lineage, we resolve branching sensory trajectories leading to first-order visual and somatosensory neurons, both emerging from a shared higher-order-like state. Using in silico predictions and in vivo perturbation, we identify Sp9 as a key regulator of visual thalamic fate. Together, our findings define the molecular architecture and developmental trajectories that underpin thalamic modality specification, providing a framework to understand how functional circuits emerge in the mammalian brain.
Project description:The thalamus integrates sensory, motor, and associative functions via distinct nuclei, yet the developmental principles driving their specification remains unclear. Here, we generate a spatiotemporal single-cell multiomic and spatial transcriptomic atlas of the embryonic mouse thalamus, combined with barcoding-based lineage tracing. We identify two major glutamatergic lineages, sensory-related and motor-associative, each governed by different gene regulatory programs and temporal dynamics. These lineages arise from spatially and molecularly distinct progenitor domains, revealing an early segregation of functional identities. Within the sensory lineage, we resolve branching sensory trajectories leading to first-order visual and somatosensory neurons, both emerging from a shared higher-order-like state. Using in silico predictions and in vivo perturbation, we identify Sp9 as a key regulator of visual thalamic fate. Together, our findings define the molecular architecture and developmental trajectories that underpin thalamic modality specification, providing a framework to understand how functional circuits emerge in the mammalian brain.
Project description:The thalamus integrates sensory, motor, and associative functions via distinct nuclei, yet the developmental principles driving their specification remains unclear. Here, we generate a spatiotemporal single-cell multiomic and spatial transcriptomic atlas of the embryonic mouse thalamus, combined with barcoding-based lineage tracing. We identify two major glutamatergic lineages, sensory-related and motor-associative, each governed by different gene regulatory programs and temporal dynamics. These lineages arise from spatially and molecularly distinct progenitor domains, revealing an early segregation of functional identities. Within the sensory lineage, we resolve branching sensory trajectories leading to first-order visual and somatosensory neurons, both emerging from a shared higher-order-like state. Using in silico predictions and in vivo perturbation, we identify Sp9 as a key regulator of visual thalamic fate. Together, our findings define the molecular architecture and developmental trajectories that underpin thalamic modality specification, providing a framework to understand how functional circuits emerge in the mammalian brain.
Project description:Nuclei of the mammalian thalamus are aggregations of neurons with unique architectures and input-output connections, yet the molecular determinants of their organizational specificity remain unknown. By comparing expression profiles of thalamus and cerebral cortex in adult rhesus monkeys we identified transcripts that are unique to dorsal thalamus or to individual nuclei within it. Real-time quantitative polymerase chain reaction and in situ hybridization analyses confirmed the findings. Expression profiling of individual nuclei microdissected from the dorsal thalamus revealed additional subsets of nucleus-specific genes. Functional annotation using Gene Ontology (GO) vocabulary and Ingenuity Pathway analysis revealed over-representation of GO categories related to development, morphogenesis, cell-cell interactions, and extracellular matrix within the thalamus- and nucleus-specific genes-many involved in the Wnt signaling pathway. Examples included the transcription factor TCF7L2, localized exclusively to excitatory neurons, a calmodulin-binding protein PCP4, the bone extracellular matrix molecules SPP1 and SPARC, and other genes involved in axon outgrowth and cell matrix interactions. Other nucleus-specific genes such as CBLN1 are involved in synaptogenesis. The genes identified likely underlie nuclear specification, cell phenotype and connectivity during development and their maintenance in the adult thalamus. Keywords: brain region comparative analysis
Project description:Peripheral sensory neurons, residing in the dorsal root ganglia (DRG), relay sensory information from the periphery to the central nervous system. Although single-cell transcriptomic studies have identified over 20 distinct sensory neuron subtypes, functional analysis and assessment of subtype-specific pathological changes remain difficult. Effective isolation and enrichment of sensory neurons are challenging yet essential for functional studies. Therefore, we used single-cell transcriptomic data from DRG to identify a panel of neuronal surface markers, including Nrxn2 and Pirt. Using these markers, we developed a fluorescence-activated cell sorting (FACS) panel for neuronal enrichment and analysis that does not rely on transgenic mouse strains and can be broadly applied. The panel was validated by microscopy and single-cell RNA (scRNA) sequencing, which also revealed broad representation of neuronal subtypes. Expression of these markers in human DRG underscores the translational value of this isolation method for sensory and pain studies. Overall, this study provides a valuable tool for isolating DRG neurons, advancing research on sensory neuron function and pain biology, and facilitating neuroimmune studies.