RESUMO
The construction of the human nervous system is a distinctly complex although highly regulated process. Human tissue inaccessibility has impeded a molecular understanding of the developmental specializations from which our unique cognitive capacities arise. A confluence of recent technological advances in genomics and stem cell-based tissue modeling is laying the foundation for a new understanding of human neural development and dysfunction in neuropsychiatric disease. Here, we review recent progress on uncovering the cellular and molecular principles of human brain organogenesis in vivo as well as using organoids and assembloids in vitro to model features of human evolution and disease.
Assuntos
Transtorno do Espectro Autista/metabolismo , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Epilepsia/metabolismo , Neurogênese/fisiologia , Esquizofrenia/metabolismo , Animais , Transtorno do Espectro Autista/genética , Encéfalo/metabolismo , Epilepsia/genética , Humanos , Mutação , Neurônios/citologia , Neurônios/metabolismo , Organoides/embriologia , Organoides/crescimento & desenvolvimento , Esquizofrenia/genéticaRESUMO
Neurons in the cerebral cortex connect through descending pathways to hindbrain and spinal cord to activate muscle and generate movement. Although components of this pathway have been previously generated and studied in vitro, the assembly of this multi-synaptic circuit has not yet been achieved with human cells. Here, we derive organoids resembling the cerebral cortex or the hindbrain/spinal cord and assemble them with human skeletal muscle spheroids to generate 3D cortico-motor assembloids. Using rabies tracing, calcium imaging, and patch-clamp recordings, we show that corticofugal neurons project and connect with spinal spheroids, while spinal-derived motor neurons connect with muscle. Glutamate uncaging or optogenetic stimulation of cortical spheroids triggers robust contraction of 3D muscle, and assembloids are morphologically and functionally intact for up to 10 weeks post-fusion. Together, this system highlights the remarkable self-assembly capacity of 3D cultures to form functional circuits that could be used to understand development and disease.
Assuntos
Córtex Cerebral/fisiologia , Córtex Motor/fisiologia , Organoides/fisiologia , Animais , Cálcio/metabolismo , Diferenciação Celular , Células Cultivadas , Vértebras Cervicais , Regulação da Expressão Gênica , Glutamatos/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Camundongos , Músculos/fisiologia , Mioblastos/metabolismo , Rede Nervosa/fisiologia , Optogenética , Organoides/ultraestrutura , Rombencéfalo/fisiologia , Esferoides Celulares/citologia , Medula Espinal/citologiaRESUMO
Microglia maintain homeostasis in the brain, but whether aberrant microglial activation can cause neurodegeneration remains controversial. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive upregulation of lysosomal and innate immunity genes, increased complement production, and enhanced synaptic pruning in microglia. During aging, Grn(-/-) mice show profound microglia infiltration and preferential elimination of inhibitory synapses in the ventral thalamus, which lead to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors. Remarkably, deleting C1qa gene significantly reduces synaptic pruning by Grn(-/-) microglia and mitigates neurodegeneration, behavioral phenotypes, and premature mortality in Grn(-/-) mice. Together, our results uncover a previously unrecognized role of progranulin in suppressing aberrant microglia activation during aging. These results represent an important conceptual advance that complement activation and microglia-mediated synaptic pruning are major drivers, rather than consequences, of neurodegeneration caused by progranulin deficiency.
Assuntos
Envelhecimento/metabolismo , Encéfalo/metabolismo , Ativação do Complemento , Complemento C1q/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Microglia/metabolismo , Envelhecimento/imunologia , Animais , Líquido Cefalorraquidiano , Complemento C1q/genética , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Granulinas , Humanos , Imunidade Inata , Peptídeos e Proteínas de Sinalização Intercelular/deficiência , Peptídeos e Proteínas de Sinalização Intercelular/genética , Lisossomos/metabolismo , Redes e Vias Metabólicas , Camundongos , Transtorno Obsessivo-Compulsivo/genética , Transtorno Obsessivo-Compulsivo/metabolismo , Progranulinas , Sinapses/metabolismo , Tálamo/metabolismoRESUMO
The assembly of cortical circuits involves the generation and migration of interneurons from the ventral to the dorsal forebrain1-3, which has been challenging to study at inaccessible stages of late gestation and early postnatal human development4. Autism spectrum disorder and other neurodevelopmental disorders (NDDs) have been associated with abnormal cortical interneuron development5, but which of these NDD genes affect interneuron generation and migration, and how they mediate these effects remains unknown. We previously developed a platform to study interneuron development and migration in subpallial organoids and forebrain assembloids6. Here we integrate assembloids with CRISPR screening to investigate the involvement of 425 NDD genes in human interneuron development. The first screen aimed at interneuron generation revealed 13 candidate genes, including CSDE1 and SMAD4. We subsequently conducted an interneuron migration screen in more than 1,000 forebrain assembloids that identified 33 candidate genes, including cytoskeleton-related genes and the endoplasmic reticulum-related gene LNPK. We discovered that, during interneuron migration, the endoplasmic reticulum is displaced along the leading neuronal branch before nuclear translocation. LNPK deletion interfered with this endoplasmic reticulum displacement and resulted in abnormal migration. These results highlight the power of this CRISPR-assembloid platform to systematically map NDD genes onto human development and reveal disease mechanisms.
Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Transtornos do Neurodesenvolvimento , Feminino , Humanos , Recém-Nascido , Gravidez , Movimento Celular/genética , Sistemas CRISPR-Cas/genética , Interneurônios/citologia , Interneurônios/metabolismo , Interneurônios/patologia , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/patologia , Organoides/citologia , Organoides/embriologia , Organoides/crescimento & desenvolvimento , Organoides/metabolismo , Organoides/patologia , Retículo Endoplasmático/metabolismo , Prosencéfalo/citologia , Prosencéfalo/embriologia , Prosencéfalo/crescimento & desenvolvimento , Prosencéfalo/metabolismo , Prosencéfalo/patologia , Transporte Ativo do Núcleo CelularRESUMO
Self-organizing neural organoids represent a promising in vitro platform with which to model human development and disease1-5. However, organoids lack the connectivity that exists in vivo, which limits maturation and makes integration with other circuits that control behaviour impossible. Here we show that human stem cell-derived cortical organoids transplanted into the somatosensory cortex of newborn athymic rats develop mature cell types that integrate into sensory and motivation-related circuits. MRI reveals post-transplantation organoid growth across multiple stem cell lines and animals, whereas single-nucleus profiling shows progression of corticogenesis and the emergence of activity-dependent transcriptional programs. Indeed, transplanted cortical neurons display more complex morphological, synaptic and intrinsic membrane properties than their in vitro counterparts, which enables the discovery of defects in neurons derived from individuals with Timothy syndrome. Anatomical and functional tracings show that transplanted organoids receive thalamocortical and corticocortical inputs, and in vivo recordings of neural activity demonstrate that these inputs can produce sensory responses in human cells. Finally, cortical organoids extend axons throughout the rat brain and their optogenetic activation can drive reward-seeking behaviour. Thus, transplanted human cortical neurons mature and engage host circuits that control behaviour. We anticipate that this approach will be useful for detecting circuit-level phenotypes in patient-derived cells that cannot otherwise be uncovered.
Assuntos
Vias Neurais , Organoides , Animais , Animais Recém-Nascidos , Transtorno Autístico , Humanos , Síndrome do QT Longo , Motivação , Neurônios/fisiologia , Optogenética , Organoides/citologia , Organoides/inervação , Organoides/transplante , Ratos , Recompensa , Córtex Somatossensorial/citologia , Córtex Somatossensorial/fisiologia , Células-Tronco/citologia , SindactiliaRESUMO
Aberrant aggregation of the RNA-binding protein TDP-43 in neurons is a hallmark of frontotemporal lobar degeneration caused by haploinsufficiency in the gene encoding progranulin1,2. However, the mechanism leading to TDP-43 proteinopathy remains unclear. Here we use single-nucleus RNA sequencing to show that progranulin deficiency promotes microglial transition from a homeostatic to a disease-specific state that causes endolysosomal dysfunction and neurodegeneration in mice. These defects persist even when Grn-/- microglia are cultured ex vivo. In addition, single-nucleus RNA sequencing reveals selective loss of excitatory neurons at disease end-stage, which is characterized by prominent nuclear and cytoplasmic TDP-43 granules and nuclear pore defects. Remarkably, conditioned media from Grn-/- microglia are sufficient to promote TDP-43 granule formation, nuclear pore defects and cell death in excitatory neurons via the complement activation pathway. Consistent with these results, deletion of the genes encoding C1qa and C3 mitigates microglial toxicity and rescues TDP-43 proteinopathy and neurodegeneration. These results uncover previously unappreciated contributions of chronic microglial toxicity to TDP-43 proteinopathy during neurodegeneration.
Assuntos
Microglia/metabolismo , Microglia/patologia , Neurônios/metabolismo , Neurônios/patologia , Progranulinas/deficiência , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologia , Envelhecimento/genética , Envelhecimento/patologia , Animais , Núcleo Celular/genética , Núcleo Celular/patologia , Ativação do Complemento/efeitos dos fármacos , Ativação do Complemento/imunologia , Complemento C1q/antagonistas & inibidores , Complemento C1q/imunologia , Complemento C3b/antagonistas & inibidores , Complemento C3b/imunologia , Meios de Cultivo Condicionados/química , Meios de Cultivo Condicionados/farmacologia , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Poro Nuclear/metabolismo , Poro Nuclear/patologia , Progranulinas/genética , RNA-Seq , Análise de Célula Única , Proteinopatias TDP-43/tratamento farmacológico , Proteinopatias TDP-43/genética , Tálamo/metabolismo , Tálamo/patologia , TranscriptomaRESUMO
New neurons continue to be generated in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus. This process has been linked to learning and memory, stress and exercise, and is thought to be altered in neurological disease. In humans, some studies have suggested that hundreds of new neurons are added to the adult dentate gyrus every day, whereas other studies find many fewer putative new neurons. Despite these discrepancies, it is generally believed that the adult human hippocampus continues to generate new neurons. Here we show that a defined population of progenitor cells does not coalesce in the subgranular zone during human fetal or postnatal development. We also find that the number of proliferating progenitors and young neurons in the dentate gyrus declines sharply during the first year of life and only a few isolated young neurons are observed by 7 and 13 years of age. In adult patients with epilepsy and healthy adults (18-77 years; n = 17 post-mortem samples from controls; n = 12 surgical resection samples from patients with epilepsy), young neurons were not detected in the dentate gyrus. In the monkey (Macaca mulatta) hippocampus, proliferation of neurons in the subgranular zone was found in early postnatal life, but this diminished during juvenile development as neurogenesis decreased. We conclude that recruitment of young neurons to the primate hippocampus decreases rapidly during the first years of life, and that neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans. The early decline in hippocampal neurogenesis raises questions about how the function of the dentate gyrus differs between humans and other species in which adult hippocampal neurogenesis is preserved.
Assuntos
Hipocampo/citologia , Neurogênese , Neurônios/citologia , Adolescente , Adulto , Idoso , Animais , Animais Recém-Nascidos , Contagem de Células , Proliferação de Células , Criança , Pré-Escolar , Giro Denteado/citologia , Giro Denteado/embriologia , Epilepsia/patologia , Feminino , Desenvolvimento Fetal , Voluntários Saudáveis , Hipocampo/anatomia & histologia , Hipocampo/embriologia , Humanos , Lactente , Macaca mulatta , Masculino , Pessoa de Meia-Idade , Células-Tronco Neurais/citologia , Adulto JovemRESUMO
Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help to refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded semaphorin 3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a leads to dysregulated α-motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α- but not of adjacent γ-motor neurons. In addition, a subset of TrkA(+) sensory afferents projects to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement.
Assuntos
Astrócitos/fisiologia , Neurônios Motores/fisiologia , Vias Neurais/fisiologia , Células Receptoras Sensoriais/fisiologia , Animais , Astrócitos/citologia , Axônios/fisiologia , Polaridade Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Camundongos , Neurônios Motores/citologia , Neurônios Motores/efeitos dos fármacos , Semaforina-3A/deficiência , Semaforina-3A/genética , Semaforina-3A/metabolismo , Semaforina-3A/farmacologia , Células Receptoras Sensoriais/citologia , Medula Espinal/citologia , Sinapses/metabolismoRESUMO
The neocortex of primates, including humans, contains more abundant and diverse inhibitory neurons compared with rodents, but the molecular foundations of these observations are unknown. Through integrative gene coexpression analysis, we determined a consensus transcriptional profile of GABAergic neurons in mid-gestation human neocortex. By comparing this profile to genes expressed in GABAergic neurons purified from neonatal mouse neocortex, we identified conserved and distinct aspects of gene expression in these cells between the species. We show here that the calcium-binding protein secretagogin (SCGN) is robustly expressed by neocortical GABAergic neurons derived from caudal ganglionic eminences (CGE) and lateral ganglionic eminences during human but not mouse brain development. Through electrophysiological and morphometric analyses, we examined the effects of SCGN expression on GABAergic neuron function and form. Forced expression of SCGN in CGE-derived mouse GABAergic neurons significantly increased total neurite length and arbor complexity following transplantation into mouse neocortex, revealing a molecular pathway that contributes to morphological differences in these cells between rodents and primates.
Assuntos
Neurônios GABAérgicos/metabolismo , Neocórtex/embriologia , Neurogênese/fisiologia , Secretagoginas/metabolismo , Animais , Humanos , Interneurônios/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Neuritos/metabolismo , TranscriptomaRESUMO
Human neural organoids represent promising models for studying neural function; however, organoids grown in vitro lack certain microenvironments and sensory inputs that are thought to be essential for maturation. The transplantation of patient-derived neural organoids into animal hosts helps overcome some of these limitations and offers an approach for neural organoid maturation and circuit integration. Here, we describe a method for transplanting human stem cell-derived cortical organoids (hCOs) into the somatosensory cortex of newborn rats. The differentiation of human induced pluripotent stem cells into hCOs occurs over 30-60 days, and the transplantation procedure itself requires ~0.5-1 hours per animal. The use of neonatal hosts provides a developmentally appropriate stage for circuit integration and allows the generation and experimental manipulation of a unit of human neural tissue within the cortex of a living animal host. After transplantation, animals can be maintained for hundreds of days, and transplanted hCO growth can be monitored by using brain magnetic resonance imaging. We describe the assessment of human neural circuit function in vivo by monitoring genetically encoded calcium responses and extracellular activity. To demonstrate human neuron-host functional integration, we also describe a procedure for engaging host neural circuits and for modulating animal behavior by using an optogenetic behavioral training paradigm. The transplanted human neurons can then undergo ex vivo characterization across modalities including dendritic morphology reconstruction, single-nucleus transcriptomics, optogenetic manipulation and electrophysiology. This approach may enable the discovery of cellular phenotypes from patient-derived cells and uncover mechanisms that contribute to human brain evolution from previously inaccessible developmental stages.
RESUMO
Tumors may contain billions of cells including distinct malignant clones and nonmalignant cell types. Clarifying the evolutionary histories, prevalence, and defining molecular features of these cells is essential for improving clinical outcomes, since intratumoral heterogeneity provides fuel for acquired resistance to targeted therapies. Here we present a statistically motivated strategy for deconstructing intratumoral heterogeneity through multiomic and multiscale analysis of serial tumor sections (MOMA). By combining deep sampling of IDH-mutant astrocytomas with integrative analysis of single-nucleotide variants, copy-number variants, and gene expression, we reconstruct and validate the phylogenies, spatial distributions, and transcriptional profiles of distinct malignant clones. By genotyping nuclei analyzed by single-nucleus RNA-seq for truncal mutations, we further show that commonly used algorithms for identifying cancer cells from single-cell transcriptomes may be inaccurate. We also demonstrate that correlating gene expression with tumor purity in bulk samples can reveal optimal markers of malignant cells and use this approach to identify a core set of genes that is consistently expressed by astrocytoma truncal clones, including AKR1C3, whose expression is associated with poor outcomes in several types of cancer. In summary, MOMA provides a robust and flexible strategy for precisely deconstructing intratumoral heterogeneity and clarifying the core molecular properties of distinct cellular populations in solid tumors.
RESUMO
Tumors may contain billions of cells, including distinct malignant clones and nonmalignant cell types. Clarifying the evolutionary histories, prevalence, and defining molecular features of these cells is essential for improving clinical outcomes, since intratumoral heterogeneity provides fuel for acquired resistance to targeted therapies. Here we present a statistically motivated strategy for deconstructing intratumoral heterogeneity through multiomic and multiscale analysis of serial tumor sections (MOMA). By combining deep sampling of IDH-mutant astrocytomas with integrative analysis of single-nucleotide variants, copy-number variants, and gene expression, we reconstruct and validate the phylogenies, spatial distributions, and transcriptional profiles of distinct malignant clones. By genotyping nuclei analyzed by single-nucleus RNA-seq for truncal mutations, we further show that commonly used algorithms for identifying cancer cells from single-cell transcriptomes may be inaccurate. We also demonstrate that correlating gene expression with tumor purity in bulk samples can reveal optimal markers of malignant cells and use this approach to identify a core set of genes that are consistently expressed by astrocytoma truncal clones, including AKR1C3, whose expression is associated with poor outcomes in several types of cancer. In summary, MOMA provides a robust and flexible strategy for precisely deconstructing intratumoral heterogeneity and clarifying the core molecular properties of distinct cellular populations in solid tumors.
RESUMO
Developmental regulation of gliogenesis in the mammalian CNS is incompletely understood, in part due to a limited repertoire of lineage-specific genes. We used Aldh1l1-GFP as a marker for gliogenic radial glia and later-stage precursors of developing astrocytes and performed gene expression profiling of these cells. We then used this dataset to identify candidate transcription factors that may serve as glial markers or regulators of glial fate. Our analysis generated a database of developmental stage-related markers of Aldh1l1+ cells between murine embryonic day 13.5-18.5. Using these data we identify the bZIP transcription factor Nfe2l1 and demonstrate that it promotes glial fate under direct Sox9 regulatory control. Thus, this dataset represents a resource for identifying novel regulators of glial development.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Isoenzimas/metabolismo , Fator 1 Relacionado a NF-E2/metabolismo , Neuroglia/metabolismo , Retinal Desidrogenase/metabolismo , Fatores de Transcrição SOX9/metabolismo , Medula Espinal/citologia , Fatores Etários , Família Aldeído Desidrogenase 1 , Animais , Diferenciação Celular , Células Cultivadas , Galinhas , Biologia Computacional , Eletroporação , Embrião de Mamíferos , Citometria de Fluxo , Perfilação da Expressão Gênica , Proteína Glial Fibrilar Ácida , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Isoenzimas/genética , Camundongos , Camundongos Transgênicos , Fator 1 Relacionado a NF-E2/genética , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/classificação , Neurônios/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Retinal Desidrogenase/genética , Fatores de Transcrição SOX9/genética , Medula Espinal/embriologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Morphogens choreograph the generation of remarkable cellular diversity in the developing nervous system. Differentiation of stem cells toward particular neural cell fates in vitro often relies upon combinatorial modulation of these signaling pathways. However, the lack of a systematic approach to understand morphogen-directed differentiation has precluded the generation of many neural cell populations, and knowledge of the general principles of regional specification remain in-complete. Here, we developed an arrayed screen of 14 morphogen modulators in human neural organoids cultured for over 70 days. Leveraging advances in multiplexed RNA sequencing technology and annotated single cell references of the human fetal brain we discovered that this screening approach generated considerable regional and cell type diversity across the neural axis. By deconvoluting morphogen-cell type relationships, we extracted design principles of brain region specification, including critical morphogen timing windows and combinatorics yielding an array of neurons with distinct neuro-transmitter identities. Tuning GABAergic neural subtype diversity unexpectedly led to the derivation of primate-specific interneurons. Taken together, this serves as a platform towards an in vitro morphogen atlas of human neural cell differentiation that will bring insights into human development, evolution, and disease.
RESUMO
It is widely assumed that cells must be physically isolated to study their molecular profiles. However, intact tissue samples naturally exhibit variation in cellular composition, which drives covariation of cell-class-specific molecular features. By analyzing transcriptional covariation in 7,221 intact CNS samples from 840 neurotypical individuals, representing billions of cells, we reveal the core transcriptional identities of major CNS cell classes in humans. By modeling intact CNS transcriptomes as a function of variation in cellular composition, we identify cell-class-specific transcriptional differences in Alzheimer's disease, among brain regions, and between species. Among these, we show that PMP2 is expressed by human but not mouse astrocytes and significantly increases mouse astrocyte size upon ectopic expression in vivo, causing them to more closely resemble their human counterparts. Our work is available as an online resource ( http://oldhamlab.ctec.ucsf.edu/ ) and provides a generalizable strategy for determining the core molecular features of cellular identity in intact biological systems.
Assuntos
Sistema Nervoso Central/citologia , Transcrição Gênica/fisiologia , Doença de Alzheimer/genética , Animais , Astrócitos/metabolismo , Astrócitos/ultraestrutura , Encéfalo/citologia , Encéfalo/metabolismo , Tamanho Celular , Bases de Dados Genéticas , Perfilação da Expressão Gênica , Humanos , Camundongos , Modelos Genéticos , Proteína P2 de Mielina/biossíntese , Proteína P2 de Mielina/genética , Análise de Sequência de RNA , TranscriptomaRESUMO
Diversified neurons are essential for sensorimotor function, but whether astrocytes become specialized to optimize circuit performance remains unclear. Large fast α-motor neurons (FαMNs) of spinal cord innervate fast-twitch muscles that generate peak strength. We report that ventral horn astrocytes express the inward-rectifying K+ channel Kir4.1 (a.k.a. Kcnj10) around MNs in a VGLUT1-dependent manner. Loss of astrocyte-encoded Kir4.1 selectively altered FαMN size and function and led to reduced peak strength. Overexpression of Kir4.1 in astrocytes was sufficient to increase MN size through activation of the PI3K/mTOR/pS6 pathway. Kir4.1 was downregulated cell autonomously in astrocytes derived from amyotrophic lateral sclerosis (ALS) patients with SOD1 mutation. However, astrocyte Kir4.1 was dispensable for FαMN survival even in the mutant SOD1 background. These findings show that astrocyte Kir4.1 is essential for maintenance of peak strength and suggest that Kir4.1 downregulation might uncouple symptoms of muscle weakness from MN cell death in diseases like ALS.
Assuntos
Astrócitos/metabolismo , Neurônios Motores/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/biossíntese , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Animais , Animais Recém-Nascidos , Astrócitos/química , Astrócitos/patologia , Células Cultivadas , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/química , Células-Tronco Pluripotentes Induzidas/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Neurônios Motores/química , Neurônios Motores/patologia , Técnicas de Cultura de Órgãos , Canais de Potássio Corretores do Fluxo de Internalização/análiseRESUMO
Neuronal synapse formation and remodeling are essential to central nervous system (CNS) development and are dysfunctional in neurodevelopmental diseases. Innate immune signals regulate tissue remodeling in the periphery, but how this affects CNS synapses is largely unknown. Here, we show that the interleukin-1 family cytokine interleukin-33 (IL-33) is produced by developing astrocytes and is developmentally required for normal synapse numbers and neural circuit function in the spinal cord and thalamus. We find that IL-33 signals primarily to microglia under physiologic conditions, that it promotes microglial synapse engulfment, and that it can drive microglial-dependent synapse depletion in vivo. These data reveal a cytokine-mediated mechanism required to maintain synapse homeostasis during CNS development.
Assuntos
Astrócitos/metabolismo , Sistema Nervoso Central/crescimento & desenvolvimento , Interleucina-33/metabolismo , Microglia/fisiologia , Rede Nervosa/crescimento & desenvolvimento , Neurogênese , Sinapses/fisiologia , Animais , Sistema Nervoso Central/metabolismo , Homeostase , Interleucina-33/genética , Camundongos , Camundongos Knockout , Córtex Sensório-Motor/crescimento & desenvolvimento , Córtex Sensório-Motor/fisiologia , Tálamo/anormalidadesRESUMO
Glial support is critical for normal axon function and can become dysregulated in white matter (WM) disease. In humans, loss-of-function mutations of KCNJ10, which encodes the inward-rectifying potassium channel KIR4.1, causes seizures and progressive neurological decline. We investigated Kir4.1 functions in oligodendrocytes (OLs) during development, adulthood and after WM injury. We observed that Kir4.1 channels localized to perinodal areas and the inner myelin tongue, suggesting roles in juxta-axonal K+ removal. Conditional knockout (cKO) of OL-Kcnj10 resulted in late onset mitochondrial damage and axonal degeneration. This was accompanied by neuronal loss and neuro-axonal dysfunction in adult OL-Kcnj10 cKO mice as shown by delayed visual evoked potentials, inner retinal thinning and progressive motor deficits. Axon pathologies in OL-Kcnj10 cKO were exacerbated after WM injury in the spinal cord. Our findings point towards a critical role of OL-Kir4.1 for long-term maintenance of axonal function and integrity during adulthood and after WM injury.
Assuntos
Axônios/metabolismo , Leucoencefalopatias/genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Convulsões/genética , Animais , Axônios/patologia , Humanos , Leucoencefalopatias/fisiopatologia , Camundongos , Camundongos Knockout , Neuroglia/metabolismo , Neuroglia/patologia , Neurônios/metabolismo , Neurônios/patologia , Oligodendroglia/metabolismo , Oligodendroglia/patologia , Convulsões/fisiopatologia , Medula Espinal/metabolismo , Medula Espinal/fisiopatologiaRESUMO
In this issue of Neuron, Zhang et al. (2016) develop a novel approach to generate populations of human astrocytes to uncover their uniquely human traits.