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Mounting evidence indicates that the nervous system plays a central role in cancer pathogenesis. In turn, cancers and cancer therapies can alter nervous system form and function. This Commentary seeks to describe the burgeoning field of "cancer neuroscience" and encourage multidisciplinary collaboration for the study of cancer-nervous system interactions.
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Neoplasias/metabolismo , Sistema Nervoso/metabolismo , Humanos , NeurociênciasRESUMO
Sonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in TMEM161B, which encodes a multi-pass transmembrane protein of unknown function. Tmem161b null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b. Tmem161b depletion impaired the response to Smoothened activation in vitro and disrupted cortical histogenesis in vivo in both mouse and ferret models, including leading to abnormal gyration in the ferret model. Tmem161b localizes non-exclusively to the primary cilium, and scanning electron microscopy revealed shortened, dysmorphic, and ballooned ventricular zone cilia in the Tmem161b null mouse, suggesting that the Shh-related phenotypes may reflect ciliary dysfunction. Our data identify TMEM161B as a regulator of cerebral cortical gyration, as involved in primary ciliary structure, as a regulator of Shh signaling, and further implicate Shh signaling in human gyral development.
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Furões , Proteínas Hedgehog , Animais , Feminino , Humanos , Camundongos , Gravidez , Sistema Nervoso Central/metabolismo , Cílios/genética , Cílios/metabolismo , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Camundongos Knockout , Transdução de SinaisRESUMO
During neural development, stem and precursor cells can divide either symmetrically or asymmetrically. The transition between symmetric and asymmetric cell divisions is a major determinant of precursor cell expansion and neural differentiation, but the underlying mechanisms that regulate this transition are not well understood. Here, we identify the Sonic hedgehog (Shh) pathway as a critical determinant regulating the mode of division of cerebellar granule cell precursors (GCPs). Using partial gain and loss of function mutations within the Shh pathway, we show that pathway activation determines spindle orientation of GCPs, and that mitotic spindle orientation correlates with the mode of division. Mechanistically, we show that the phosphatase Eya1 is essential for implementing Shh-dependent GCP spindle orientation. We identify atypical protein kinase C (aPKC) as a direct target of Eya1 activity and show that Eya1 dephosphorylates a critical threonine (T410) in the activation loop. Thus, Eya1 inactivates aPKC, resulting in reduced phosphorylation of Numb and other components that regulate the mode of division. This Eya1-dependent cascade is critical in linking spindle orientation, cell cycle exit and terminal differentiation. Together these findings demonstrate that a Shh-Eya1 regulatory axis selectively promotes symmetric cell divisions during cerebellar development by coordinating spindle orientation and cell fate determinants.
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Divisão Celular/fisiologia , Cerebelo/metabolismo , Proteínas Hedgehog/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Células-Tronco Neurais/metabolismo , Neurogênese/fisiologia , Proteínas Nucleares/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Animais , Cerebelo/embriologia , Cerebelo/crescimento & desenvolvimento , Camundongos , Camundongos Mutantes , Células-Tronco Neurais/citologia , Transdução de Sinais/fisiologiaRESUMO
Low-grade gliomas represent the most frequent brain tumors arising during childhood. They are characterized by a broad and heterogeneous group of tumors that are currently classified by the WHO according to their morphological appearance. Here we review the clinical features of these tumors, current therapeutic strategies and the recent discovery of genomic alterations characteristic to these tumors. We further explore how these recent biological findings stand to transform the treatment for these tumors and impact the diagnostic criteria for pediatric low-grade gliomas.
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Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Glioma/patologia , Glioma/terapia , Apoptose/genética , Neoplasias Encefálicas/epidemiologia , Neoplasias Encefálicas/genética , Sobrevivência Celular/genética , Epigênese Genética/genética , Glioma/epidemiologia , Glioma/genética , Humanos , Terapia de Alvo Molecular , Gradação de Tumores , Pediatria , PrognósticoRESUMO
Establishment of neuronal circuitry depends on both formation and refinement of neural connections. During this process, target-derived neurotrophins regulate both transcription and translation to enable selective axon survival or elimination. However, it is not known whether retrograde signaling pathways that control transcription are coordinated with neurotrophin-regulated actions that transpire in the axon. Here we report that target-derived neurotrophins coordinate transcription of the antiapoptotic gene bclw with transport of bclw mRNA to the axon, and thereby prevent axonal degeneration in rat and mouse sensory neurons. We show that neurotrophin stimulation of nerve terminals elicits new bclw transcripts that are immediately transported to the axons and translated into protein. Bclw interacts with Bax and suppresses the caspase6 apoptotic cascade that fosters axonal degeneration. The scope of bclw regulation at the levels of transcription, transport, and translation provides a mechanism whereby sustained neurotrophin stimulation can be integrated over time, so that axonal survival is restricted to neurons connected within a stable circuit.
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Transporte Axonal/fisiologia , Degeneração Neural/fisiopatologia , Fatores de Crescimento Neural/metabolismo , Proteínas/genética , Células Receptoras Sensoriais/fisiologia , Proteína bcl-X/genética , Animais , Apoptose/fisiologia , Proteínas Reguladoras de Apoptose , Transporte Axonal/efeitos dos fármacos , Axônios/efeitos dos fármacos , Axônios/fisiologia , Caspase 6/metabolismo , Células Cultivadas , Feminino , Gânglios Espinais/citologia , Humanos , Masculino , Camundongos , Degeneração Neural/tratamento farmacológico , Degeneração Neural/metabolismo , Fatores de Crescimento Neural/farmacologia , Gravidez , Proteínas/metabolismo , RNA Mensageiro/metabolismo , Ratos , Células Receptoras Sensoriais/citologia , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/fisiologia , Proteína bcl-X/metabolismoRESUMO
Sonic Hedgehog (Shh) signaling is crucial for growth, cell fate determination, and axonal guidance in the developing nervous system. Although the receptors Patched (Ptch1) and Smoothened (Smo) are required for Shh signaling, a number of distinct co-receptors contribute to these critical responses to Shh. Several membrane-embedded proteins such as Boc, Cdo, and Gas1 bind Shh and promote signaling. In addition, heparan sulfate proteoglycans (HSPGs) have also been implicated in the initiation of Shh responses. However, the attributes of HSPGs that function as co-receptors for Shh have not yet been defined. Here, we identify HSPGs containing a glypican 5 core protein and 2-O-sulfo-iduronic acid residues at the nonreducing ends of the glycans as co-receptors for Shh. These HSPG co-receptors are expressed by cerebellar granule cell precursors and promote Shh binding and signaling. At the subcellular level, these HSPG co-receptors are located adjacent to the primary cilia that act as Shh signaling organelles. Thus, Shh binds to HSPG co-receptors containing a glypican 5 core and 2-O-sulfo-iduronic acid to promote neural precursor proliferation.
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Proliferação de Células , Cerebelo/metabolismo , Glipicanas/metabolismo , Proteínas Hedgehog/metabolismo , Células-Tronco Neurais/metabolismo , Transdução de Sinais/fisiologia , Animais , Células COS , Cerebelo/citologia , Chlorocebus aethiops , Regulação da Expressão Gênica/fisiologia , Glipicanas/genética , Células HEK293 , Proteínas Hedgehog/genética , Humanos , Camundongos , Proteínas do Tecido Nervoso , Células-Tronco Neurais/citologiaRESUMO
Many glial biologists consider glia the neglected cells of the nervous system. Among all the glia of the central and peripheral nervous system, satellite glia may be the most often overlooked. Satellite glial cells (SGCs) are located in ganglia of the cranial nerves and the peripheral nervous system. These small cells surround the cell bodies of neurons in the trigeminal ganglia (TG), spiral ganglia, nodose and petrosal ganglia, sympathetic ganglia, and dorsal root ganglia (DRG). Essential SGC features include their intimate connections with the associated neurons, their small size, and their derivation from neural crest cells. Yet SGCs also exhibit tissue-specific properties and can change rapidly, particularly in response to injury. To illustrate the range of SGC functions, we will focus on three types: those of the spiral, sympathetic, and DRG, and consider both their shared features and those that differ based on location.
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BCL-w is a BCL-2 family protein that promotes cell survival in tissue- and disease-specific contexts. The canonical anti-apoptotic functionality of BCL-w is mediated by a surface groove that traps the BCL-2 homology 3 (BH3) α-helices of pro-apoptotic members, blocking cell death. A distinct N-terminal portion of BCL-w, termed the BCL-2 homology 4 (BH4) domain, selectively protects axons from paclitaxel-induced degeneration by modulating IP3 receptors, a noncanonical BCL-2 family target. Given the potential of BCL-w BH4 mimetics to prevent or mitigate chemotherapy-induced peripheral neuropathy, we sought to characterize the interaction between BCL-w BH4 and the IP3 receptor, combining "staple" and alanine scanning approaches with molecular dynamics simulations. We generated and identified stapled BCL-w BH4 peptides with optimized IP3 receptor binding and neuroprotective activities. Point mutagenesis further revealed the sequence determinants for BCL-w BH4 specificity, providing a blueprint for therapeutic targeting of IP3 receptors to achieve neuroprotection.
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Sonic hedgehog subgroup of medulloblastoma (SHH-MB) is characterized by aberrant activation of the SHH signaling pathway. An inhibition of the positive SHH regulator Smoothened (SMO) has demonstrated promising clinical efficacy. Yet, primary and acquired resistance to SMO inhibitors limit their efficacy. An understanding of underlying molecular mechanisms of resistance to therapy is warranted to bridge this unmet need. Here, we make use of genome-wide CRISPR-Cas9 knockout screens in murine SMB21 and human DAOY cells, in order to unravel genetic dependencies and drug-related genetic interactors that could serve as alternative therapeutic targets for SHH-MB. Our screens reinforce SMB21 cells as a faithful model system for SHH-MB, as opposed to DAOY cells, and identify members of the epigenetic machinery including DNA methyltransferase 1 (DNMT1) as druggable targets in SHH-dependent tumors. We show that Dnmt1 plays a crucial role in normal murine cerebellar development and is required for SHH-MB growth in vivo. Additionally, DNMT1 pharmacological inhibition alone and in combination with SMO inhibition effectively inhibits tumor growth in murine and human SHH-MB cell models and prolongs survival of SHH-MB mouse models by inhibiting SHH signaling output downstream of SMO. In conclusion, our data highlight the potential of inhibiting epigenetic regulators as a novel therapeutic avenue in SMO-inhibitor sensitive as well as resistant SHH-MBs.
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Sistemas CRISPR-Cas , Neoplasias Cerebelares , DNA (Citosina-5-)-Metiltransferase 1 , Proteínas Hedgehog , Meduloblastoma , Meduloblastoma/genética , Meduloblastoma/metabolismo , Meduloblastoma/patologia , Animais , DNA (Citosina-5-)-Metiltransferase 1/genética , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Humanos , Camundongos , Linhagem Celular Tumoral , Receptor Smoothened/genética , Receptor Smoothened/metabolismo , Técnicas de Inativação de Genes/métodosRESUMO
Medulloblastoma is one of the most common malignant brain tumors of children, and 30% of medulloblastomas are driven by gain-of-function genetic lesions in the Sonic Hedgehog (SHH) signaling pathway. EYA1, a haloacid dehalogenase phosphatase and transcription factor, is critical for tumorigenesis and proliferation of SHH medulloblastoma (SHH-MB). Benzarone and benzbromarone have been identified as allosteric inhibitors of EYA proteins. Using benzarone as a point of departure, we developed a panel of 35 derivatives and tested them in SHH-MB. Among these compounds, DS-1-38 functioned as an EYA antagonist and opposed SHH signaling. DS-1-38 inhibited SHH-MB growth in vitro and in vivo, showed excellent brain penetrance, and increased the lifespan of genetically engineered mice predisposed to fatal SHH-MB. These data suggest that EYA inhibitors represent promising therapies for pediatric SHH-MB. SIGNIFICANCE: Development of a benzarone derivative that inhibits EYA1 and impedes the growth of SHH medulloblastoma provides an avenue for improving treatment of this malignant pediatric brain cancer.
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Benzobromarona/análogos & derivados , Neoplasias Encefálicas , Neoplasias Cerebelares , Meduloblastoma , Animais , Camundongos , Humanos , Criança , Proteínas Hedgehog , Meduloblastoma/tratamento farmacológico , Meduloblastoma/genética , Neoplasias Cerebelares/tratamento farmacológicoRESUMO
Many genes that drive normal cellular development also contribute to oncogenesis. Medulloblastoma (MB) tumors likely arise from neuronal progenitors in the cerebellum, and we hypothesized that the heterogeneity observed in MBs with sonic hedgehog (SHH) activation could be due to differences in developmental pathways. To investigate this question, here we perform single-nucleus RNA sequencing on highly differentiated SHH MBs with extensively nodular histology and observed malignant cells resembling each stage of canonical granule neuron development. Through innovative computational approaches, we connect these results to published datasets and find that some established molecular subtypes of SHH MB appear arrested at different developmental stages. Additionally, using multiplexed proteomic imaging and MALDI imaging mass spectrometry, we identify distinct histological and metabolic profiles for highly differentiated tumors. Our approaches are applicable to understanding the interplay between heterogeneity and differentiation in other cancers and can provide important insights for the design of targeted therapies.
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Neoplasias Cerebelares , Meduloblastoma , Humanos , Proteínas Hedgehog/genética , Meduloblastoma/genética , Proteômica , Cerebelo , Neoplasias Cerebelares/genéticaRESUMO
Small fiber sensory neuropathy is a common disorder in which progressive degeneration of small-diameter nociceptors causes decreased sensitivity to thermal stimuli and painful sensations in the extremities. In the majority of patients, the cause of small fiber sensory neuropathy is unknown, and treatment options are limited. Here, we show that Bcl-w (Bcl-2l2) is required for the viability of small fiber nociceptive sensory neurons. Bcl-w(-/-) mice demonstrate an adult-onset progressive decline in thermosensation and a decrease in nociceptor innervation of the epidermis. This denervation occurs without cell body loss, indicating that lack of Bcl-w results in a primary axonopathy. Consistent with this phenotype, we show that Bcl-w, in contrast to the closely related Bcl-2 and Bcl-xL, is enriched in axons of sensory neurons and that Bcl-w prevents the dying back of axons. Bcl-w(-/-) sensory neurons exhibit mitochondrial abnormalities, including alterations in axonal mitochondrial size, axonal mitochondrial membrane potential, and cellular ATP levels. Collectively, these data establish bcl-w(-/-) mice as an animal model of small fiber sensory neuropathy and provide new insight regarding the role of Bcl-w and of mitochondria in preventing axonal degeneration.
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Axônios/patologia , Epiderme/inervação , Mitocôndrias/metabolismo , Nociceptores/metabolismo , Doenças do Sistema Nervoso Periférico/genética , Proteínas/metabolismo , Sensação Térmica/genética , Trifosfato de Adenosina/metabolismo , Animais , Proteínas Reguladoras de Apoptose , Comportamento Animal , Western Blotting , Contagem de Células , Células Cultivadas , Modelos Animais de Doenças , Feminino , Gânglios Espinais/citologia , Camundongos , Fibras Nervosas/patologia , Testes Neuropsicológicos , Doenças do Sistema Nervoso Periférico/metabolismo , Doenças do Sistema Nervoso Periférico/patologia , Gravidez , Proteínas/genética , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Limiar SensorialRESUMO
How do neurons integrate intracellular communication from synapse to nucleus and back? Here we briefly summarize aspects of this topic covered by a symposium at Neuroscience 2011. A rich repertoire of signaling mechanisms link both dendritic terminals and axon tips with neuronal soma and nucleus, using motor-dependent transport machineries to traverse the long intracellular distances along neuronal processes. Activation mechanisms at terminals include localized translation of dendritic or axonal RNA, proteolytic cleavage of receptors or second messengers, and differential phosphorylation of signaling moieties. Signaling complexes may be transported in endosomes, or as non-endosomal complexes associated with importins and dynein. Anterograde transport of RNA granules from the soma to neuronal processes, coupled with retrograde transport of proteins translated locally at terminals or within processes, may fuel ongoing bidirectional communication between soma and synapse to modulate synaptic plasticity as well as neuronal growth and survival decisions.
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Núcleo Celular/fisiologia , Neurônios/citologia , Transdução de Sinais/fisiologia , Sinapses/fisiologia , Transporte Ativo do Núcleo Celular/genética , Transporte Ativo do Núcleo Celular/fisiologia , AnimaisRESUMO
Background: High-grade gliomas (HGG) in children have a devastating prognosis and occur in a remarkable spatiotemporal pattern. Diffuse midline gliomas (DMG), including diffuse intrinsic pontine gliomas (DIPG), typically occur in mid-childhood, while cortical HGGs are more frequent in older children and adults. The mechanisms behind this pattern are not clear. Methods: We used mouse organotypic slice cultures and glial cell cultures to test the impact of the microenvironment on human DIPG cells. Comparing the expression between brainstem and cortical microglia identified differentially expressed secreted proteins. The impact of some of these proteins on DIPGs was tested. Results: DIPGs, pediatric HGGs of brainstem origin, survive and divide more in organotypic slice cultures originating in the brainstem as compared to the cortex. Moreover, brainstem microglia are better able to support tumors of brainstem origin. A comparison between the two microglial populations revealed differentially expressed genes. One such gene, interleukin-33 (IL33), is highly expressed in the pons of young mice and its DIPG receptor is upregulated in this context. Consistent with this observation, the expression levels of IL33 and its receptor, IL1RL1, are higher in DIPG biopsies compared to low-grade cortical gliomas. Furthermore, IL33 can enhance proliferation and clonability of HGGs of brainstem origin, while blocking IL33 in brainstem organotypic slice cultures reduced the proliferation of these tumor cells. Conclusions: Crosstalk between DIPGs and the brainstem microenvironment, in particular microglia, through IL33 and other secreted factors, modulates spatiotemporal patterning of this HGG and could prove to be an important future therapeutic target.
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Cancer patients frequently develop chemotherapy-induced peripheral neuropathy (CIPN), a painful and long-lasting disorder with profound somatosensory deficits. There are no effective therapies to prevent or treat this disorder. Pathologically, CIPN is characterized by a "dying-back" axonopathy that begins at intra-epidermal nerve terminals of sensory neurons and progresses in a retrograde fashion. Calcium dysregulation constitutes a critical event in CIPN, but it is not known how chemotherapies such as paclitaxel alter intra-axonal calcium and cause degeneration. Here, we demonstrate that paclitaxel triggers Sarm1-dependent cADPR production in distal axons, promoting intra-axonal calcium flux from both intracellular and extracellular calcium stores. Genetic or pharmacologic antagonists of cADPR signaling prevent paclitaxel-induced axon degeneration and allodynia symptoms, without mitigating the anti-neoplastic efficacy of paclitaxel. Our data demonstrate that cADPR is a calcium-modulating factor that promotes paclitaxel-induced axon degeneration and suggest that targeting cADPR signaling provides a potential therapeutic approach for treating paclitaxel-induced peripheral neuropathy (PIPN).
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Proteínas do Domínio Armadillo/metabolismo , Axônios/metabolismo , Cálcio/metabolismo , ADP-Ribose Cíclica/metabolismo , Proteínas do Citoesqueleto/metabolismo , Degeneração Neural/patologia , Paclitaxel/efeitos adversos , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/metabolismo , Animais , Canais de Cálcio/metabolismo , ADP-Ribose Cíclica/antagonistas & inibidores , Feminino , Células HEK293 , Humanos , Camundongos Endogâmicos C57BL , Ratos Sprague-DawleyRESUMO
Background: Pediatric gliomas comprise a diverse set of brain tumor entities that have substantial long-term ramifications for patient survival and quality of life. However, the study of these tumors is currently limited due to a lack of authentic models. Additionally, many aspects of pediatric brain tumor biology, such as tumor cell invasiveness, have been difficult to study with currently available tools. To address these issues, we developed a synthetic extracellular matrix (sECM)-based culture system to grow and study primary pediatric brain tumor cells. Methods: We developed a brain-like sECM material as a supportive scaffold for the culture of primary, patient-derived pediatric glioma cells and established patient-derived cell lines. Primary juvenile brainstem-derived murine astrocytes were used as a feeder layer to support the growth of primary human tumor cells. Results: We found that our culture system facilitated the proliferation of various primary pediatric brain tumors, including low-grade gliomas, and enabled ex vivo testing of investigational therapeutics. Additionally, we found that tuning this sECM material allowed us to assess high-grade pediatric glioma cell invasion and evaluate therapeutic interventions targeting invasive behavior. Conclusion: Our sECM culture platform provides a multipurpose tool for pediatric brain tumor researchers that enables both a wide breadth of biological assays and the cultivation of diverse tumor types.
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During development, neural precursors migrate in response to positional cues such as growth factor gradients. However, the mechanisms that enable precursors to sense and respond to such gradients are poorly understood. Here we show that cerebellar granule cell precursors (GCPs) migrate along a gradient of brain-derived neurotrophic factor (BDNF), and we demonstrate that vesicle trafficking is critical for this chemotactic process. Activation of TrkB, the BDNF receptor, stimulates GCPs to secrete BDNF, thereby amplifying the ambient gradient. The BDNF gradient stimulates endocytosis of TrkB and associated signaling molecules, causing asymmetric accumulation of signaling endosomes at the subcellular location where BDNF concentration is maximal. Thus, regulated BDNF exocytosis and TrkB endocytosis enable precursors to polarize and migrate in a directed fashion along a shallow BDNF gradient.
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Fator Neurotrófico Derivado do Encéfalo/fisiologia , Cerebelo/citologia , Quimiotaxia/efeitos dos fármacos , Endossomos/fisiologia , Transdução de Sinais/fisiologia , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Movimento Celular/efeitos dos fármacos , Cerebelo/efeitos dos fármacos , Grânulos Citoplasmáticos/fisiologia , Endocitose/efeitos dos fármacos , Lentivirus/genética , Camundongos , Camundongos Knockout , Neuropeptídeos/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Receptor trkB/metabolismo , Células-Tronco/efeitos dos fármacos , Proteína cdc42 de Ligação ao GTP/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
The peripheral nervous system responds to a wide variety of sensory stimuli, a process that requires great neuronal diversity. These diverse neurons are closely associated with glial cells originating from the neural crest. However, the molecular nature and diversity among peripheral glia are not understood. Here, we used single-cell RNA sequencing to profile developing and mature glia from somatosensory dorsal root ganglia and auditory spiral ganglia. We found that glial precursors (GPs) in these two systems differ in their transcriptional profiles. Despite their unique features, somatosensory and auditory GPs undergo convergent differentiation to generate molecularly uniform myelinating and non-myelinating Schwann cells. By contrast, somatosensory and auditory satellite glial cells retain system-specific features. Lastly, we identified a glial signature gene set, providing new insights into commonalities among glia across the nervous system. This survey of gene expression in peripheral glia constitutes a resource for understanding functions of glia across different sensory modalities.