RESUMO
Major advances have been made in utilizing human-induced pluripotent stem cells (hiPSCs) for regenerative medicine. Nevertheless, the delivery and integration of hiPSCs into target tissues remain significant challenges, particularly in the context of retinal ganglion cell (RGC) restoration. In this study, we introduce a promising avenue for providing directional guidance to regenerated cells in the retina. First, we developed a technique for construction of gradient interfaces based on functionalized conductive polymers, which could be applied with various functionalized ehthylenedioxythiophene (EDOT) monomers. Using a tree-shaped channel encapsulated with a thin PDMS and a specially designed electrochemical chamber, gradient flow generation could be converted into a functionalized-PEDOT gradient film by cyclic voltammetry. The characteristics of the successfully fabricated gradient flow and surface were analyzed using fluorescent labels, time of flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS). Remarkably, hiPSC-RGCs seeded on PEDOT exhibited improvements in neurite outgrowth, axon guidance and neuronal electrophysiology measurements. These results suggest that our novel gradient PEDOT may be used with hiPSC-based technologies as a potential biomedical engineering scaffold for functional restoration of RGCs in retinal degenerative diseases and optic neuropathies.
Assuntos
Células-Tronco Pluripotentes Induzidas , Polímeros , Células Ganglionares da Retina , Humanos , Células Ganglionares da Retina/metabolismo , Células Ganglionares da Retina/citologia , Células-Tronco Pluripotentes Induzidas/citologia , Polímeros/química , Orientação de Axônios , Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Propriedades de Superfície , Condutividade Elétrica , Fatores de Crescimento Neural/metabolismo , Axônios/metabolismo , Axônios/fisiologiaRESUMO
The axon guidance cue netrin-1 signals through its receptor DCC (deleted in colorectal cancer) to attract commissural axons to the midline. Variants in DCC are frequently associated with congenital mirror movements (CMMs). A CMM-associated variant in the cytoplasmic tail of DCC is located in a conserved motif predicted to bind to a regulator of actin dynamics called the WAVE (Wiskott-Aldrich syndrome protein-family verprolin homologous protein) regulatory complex (WRC). Here, we explored how this variant affects DCC function and may contribute to CMM. We found that a conserved WRC-interacting receptor sequence (WIRS) motif in the cytoplasmic tail of DCC mediated the interaction between DCC and the WRC. This interaction was required for netrin-1-mediated axon guidance in cultured rodent commissural neurons. Furthermore, the WIRS motif of Fra, the Drosophila DCC ortholog, was required for attractive signaling in vivo at the Drosophila midline. The CMM-associated R1343H variant of DCC, which altered the WIRS motif, prevented the DCC-WRC interaction and impaired axon guidance in cultured commissural neurons and in Drosophila. The findings reveal the WRC as a pivotal component of netrin-1-DCC signaling and uncover a molecular mechanism explaining how a human genetic variant in the cytoplasmic tail of DCC may lead to CMM.
Assuntos
Orientação de Axônios , Receptor DCC , Proteínas de Drosophila , Netrina-1 , Netrina-1/metabolismo , Netrina-1/genética , Receptor DCC/metabolismo , Receptor DCC/genética , Animais , Humanos , Orientação de Axônios/genética , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Ratos , Proteínas Supressoras de Tumor/metabolismo , Proteínas Supressoras de Tumor/genética , Axônios/metabolismo , Axônios/fisiologia , Receptores de Superfície Celular/metabolismo , Receptores de Superfície Celular/genética , Transdução de Sinais , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Camundongos , Neurônios/metabolismo , Células HEK293 , Receptores de NetrinaRESUMO
Spatially and temporally accurate termination of axon outgrowth, a process called axon termination, is required for efficient, precise nervous system construction and wiring. The mechanosensory neurons that sense low-threshold mechanical stimulation or gentle touch have proven exceptionally valuable for studying axon termination over the past 40â years. In this Review, we discuss progress made in deciphering the molecular and genetic mechanisms that govern axon termination in touch receptor neurons. Findings across model organisms, including Caenorhabditis elegans, Drosophila, zebrafish and mice, have revealed that complex signaling is required for termination with conserved principles and players beginning to surface. A key emerging theme is that axon termination is mediated by complex signaling networks that include ubiquitin ligase signaling hubs, kinase cascades, transcription factors, guidance/adhesion receptors and growth factors. Here, we begin a discussion about how these signaling networks could represent termination codes that trigger cessation of axon outgrowth in different species and types of mechanosensory neurons.
Assuntos
Axônios , Transdução de Sinais , Animais , Axônios/metabolismo , Axônios/fisiologia , Mecanorreceptores/metabolismo , Caenorhabditis elegans/metabolismo , Drosophila/metabolismoRESUMO
BACKGROUND: We aimed to identify different Guillain-Barré syndrome (GBS) subtypes, demyelination, axonal degeneration, and reversible conduction failure (RCF) as early as possible by analyzing the initial clinical and electrophysiological examinations. METHODS: This study retrospectively collected GBS patients between October 2018 and December 2022 at Beijing Tiantan Hospital. The diagnostic criteria for the initial electrophysiological study were based on Rajabally's criteria, and the criteria for the serial electrophysiological study were based on Uncini's criteria. All subjects underwent clinical and electrophysiological evaluations at least twice within 8 weeks. RESULTS: A total of 47 eligible patients with GBS were included, comprising 19 acute inflammatory demyelinating polyradiculoneuropathy (AIDP), 18 axonal degenerations, and 10 RCFs. In the RCF group, 40%, 30%, and 30% patients were diagnosed as AIDP, axonal, and equivocal at the initial study, respectively. The AIDP group had significantly higher cerebrospinal fluid (CSF) protein than the RCF (123.8 [106.4, 215.1] mg/dL vs. 67.1 [36.8, 85.6] mg/dL, p = 0.002) and axonal degeneration (123.8 [106.4, 215.1] mg/dL vs. 60.8 [34.8, 113.0] mg/dL, p < 0.001) groups. The RCF group had significantly lower Hughes functional grades at admission (3 [2, 4] vs. 4 [4, 4], p = 0.012) and discharge (1.0 [1.0, 2.0] vs. 3.0 [2.0, 3.0], p < 0.001) than the axonal degeneration group and showed significantly shorter distal motor latency (DML), Fmin, Fmean, Fmax, and lower F% than the AIDP group (p < 0.05). DISCUSSION: The early identification of RCF from AIDP had relatively obvious features, including slightly elevated CSF protein levels and normal or slightly prolonged DML and F-wave latencies, contrasting with the apparent elevation and prolongation seen in AIDP. Differentiating RCF from axonal degeneration remains challenging. One potential distinguishing factor is that the motor function in RCF tends to be better than in the latter.
Assuntos
Síndrome de Guillain-Barré , Condução Nervosa , Humanos , Síndrome de Guillain-Barré/diagnóstico , Síndrome de Guillain-Barré/fisiopatologia , Síndrome de Guillain-Barré/classificação , Síndrome de Guillain-Barré/líquido cefalorraquidiano , Feminino , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto , Condução Nervosa/fisiologia , Idoso , Eletrodiagnóstico/métodos , Eletrodiagnóstico/normas , Axônios/fisiologia , Axônios/patologia , Adulto JovemRESUMO
Neurons establish functional connections responsible for how we perceive and react to the world around us. Communication from a neuron to its target cell occurs through a long projection called an axon. Axon distances can exceed 1 m in length in humans and require a dynamic microtubule cytoskeleton for growth during development and maintenance in adulthood. Stathmins are microtubule-associated proteins that function as relays between kinase signaling and microtubule polymerization. In this review, we describe the prolific role of Stathmins in microtubule homeostasis with an emphasis on emerging roles for Stathmin-2 (Stmn2) in axon integrity and neurodegeneration. Stmn2 levels are altered in Amyotrophic Lateral Sclerosis and loss of Stmn2 provokes motor and sensory neuropathies. There is growing potential for employing Stmn2 as a disease biomarker or even a therapeutic target. Meeting this potential requires a mechanistic understanding of emerging complexity in Stmn2 function. In particular, Stmn2 palmitoylation has a surprising contribution to axon maintenance through undefined mechanisms linking membrane association, tubulin interaction, and axon transport. Exploring these connections will reveal new insight on neuronal cell biology and novel opportunities for disease intervention.
Assuntos
Axônios , Microtúbulos , Estatmina , Estatmina/metabolismo , Microtúbulos/metabolismo , Humanos , Axônios/metabolismo , Axônios/fisiologia , Animais , Membrana Celular/metabolismo , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologiaRESUMO
BACKGROUND: Traumatic brain injury (TBI) causes axon tearing and synapse degradation, resulting in multiple neurological dysfunctions and exacerbation of early neurodegeneration; the repair of axonal and synaptic structures is critical for restoring neuronal function. C-C Motif Chemokine Ligand 5 (CCL5) shows many neuroprotective activities. METHOD: A close-head weight-drop system was used to induce mild brain trauma in C57BL/6 (wild-type, WT) and CCL5 knockout (CCL5-KO) mice. The mNSS score, rotarod, beam walking, and sticker removal tests were used to assay neurological function after mTBI in different groups of mice. The restoration of motor and sensory functions was impaired in CCL5-KO mice after one month of injury, with swelling of axons and synapses from Golgi staining and reduced synaptic proteins-synaptophysin and PSD95. Administration of recombinant CCL5 (Pre-treatment: 300 pg/g once before injury; or post-treatment: 30 pg/g every 2 days, since 3 days after injury for 1 month) through intranasal delivery into mouse brain improved the motor and sensory neurological dysfunctions in CCL5-KO TBI mice. RESULTS: Proteomic analysis using LC-MS/MS identified that the "Nervous system development and function"-related proteins, including axonogenesis, synaptogenesis, and myelination signaling pathways, were reduced in injured cortex of CCL5-KO mice; both pre-treatment and post-treatment with CCL5 augmented those pathways. Immunostaining and western blot analysis confirmed axonogenesis and synaptogenesis related Semaphorin, Ephrin, p70S6/mTOR signaling, and myelination-related Neuregulin/ErbB and FGF/FAK signaling pathways were up-regulated in the cortical tissue by CCL5 after brain injury. We also noticed cortex redevelopment after long-term administration of CCL5 after brain injury with increased Reelin positive Cajal-Rerzius Cells and CXCR4 expression. CCL5 enhanced the growth of cone filopodia in a primary neuron culture system; blocking CCL5's receptor CCR5 by Maraviroc reduced the intensity of filopodia in growth cone and also CCL5 mediated mTOR and Rho signalling activation. Inhibiting mTOR and Rho signaling abolished CCL5 induced growth cone formation. CONCLUSIONS: CCL5 plays a critical role in starting the intrinsic neuronal regeneration system following TBI, which includes growth cone formation, axonogenesis and synaptogensis, remyelination, and the subsequent proper wiring of cortical circuits. Our study underscores the potential of CCL5 as a robust therapeutic stratagem in treating axonal injury and degeneration during the chronic phase after mild brain injury.
Assuntos
Axônios , Quimiocina CCL5 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Animais , Camundongos , Quimiocina CCL5/metabolismo , Axônios/metabolismo , Axônios/fisiologia , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/fisiopatologia , Masculino , Neurônios/metabolismo , Lesões Encefálicas/metabolismo , NeurogêneseRESUMO
Peripheral nerve and large-scale muscle injuries result in significant disability, necessitating the development of biomaterials that can restore functional deficits by promoting tissue regrowth in an electroactive environment. Among these materials, graphene is favored for its high conductivity, but its low bioactivity requires enhancement through biomimetic components. In this study, we extrusion printed graphene-poly(lactide-co-glycolide) (graphene) lattice scaffolds, aiming to increase bioactivity by incorporating decellularized extracellular matrix (dECM) derived from mouse pup skeletal muscle. We first evaluated these scaffolds using human-induced pluripotent stem cell (hiPSC)-derived motor neurons co-cultured with supportive glia, observing significant improvements in axon outgrowth. Next, we tested the scaffolds with C2C12 mouse and human primary myoblasts, finding no significant differences in myotube formation between dECM-graphene and graphene scaffolds. Finally, using a more complex hiPSC-derived 3D motor neuron spheroid model co-cultured with human myoblasts, we demonstrated that dECM-graphene scaffolds significantly improved axonal expansion towards peripheral myoblasts and increased axonal network density compared to graphene-only scaffolds. Features of early neuromuscular junction formation were identified near neuromuscular interfaces in both scaffold types. These findings suggest that dECM-graphene scaffolds are promising candidates for enhancing neuromuscular regeneration, offering robust support for the growth and development of diverse neuromuscular tissues.
Assuntos
Técnicas de Cocultura , Matriz Extracelular , Grafite , Células-Tronco Pluripotentes Induzidas , Alicerces Teciduais , Grafite/química , Animais , Alicerces Teciduais/química , Camundongos , Humanos , Matriz Extracelular/química , Células-Tronco Pluripotentes Induzidas/citologia , Neurônios Motores/fisiologia , Neurônios Motores/citologia , Axônios/fisiologia , Mioblastos/citologia , Engenharia Tecidual/métodos , Crescimento Neuronal/efeitos dos fármacos , Crescimento Neuronal/fisiologia , Músculo Esquelético/fisiologia , Músculo Esquelético/citologia , Diferenciação Celular , Junção Neuromuscular/fisiologiaRESUMO
Adult central nervous system (CNS) neurons down-regulate growth programs after injury, leading to persistent regeneration failure. Coordinated lipids metabolism is required to synthesize membrane components during axon regeneration. However, lipids also function as cell signaling molecules. Whether lipid signaling contributes to axon regeneration remains unclear. In this study, we showed that lipin1 orchestrates mechanistic target of rapamycin (mTOR) and STAT3 signaling pathways to determine axon regeneration. We established an mTOR-lipin1-phosphatidic acid/lysophosphatidic acid-mTOR loop that acts as a positive feedback inhibitory signaling, contributing to the persistent suppression of CNS axon regeneration following injury. In addition, lipin1 knockdown (KD) enhances corticospinal tract (CST) sprouting after unilateral pyramidotomy and promotes CST regeneration following complete spinal cord injury (SCI). Furthermore, lipin1 KD enhances sensory axon regeneration after SCI. Overall, our research reveals that lipin1 functions as a central regulator to coordinate mTOR and STAT3 signaling pathways in the CNS neurons and highlights the potential of lipin1 as a promising therapeutic target for promoting the regeneration of motor and sensory axons after SCI.
Assuntos
Axônios , Neurônios Motores , Regeneração Nervosa , Fosfatidato Fosfatase , Fator de Transcrição STAT3 , Transdução de Sinais , Traumatismos da Medula Espinal , Serina-Treonina Quinases TOR , Traumatismos da Medula Espinal/metabolismo , Traumatismos da Medula Espinal/patologia , Traumatismos da Medula Espinal/genética , Animais , Axônios/metabolismo , Axônios/fisiologia , Regeneração Nervosa/fisiologia , Fator de Transcrição STAT3/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Fosfatidato Fosfatase/metabolismo , Fosfatidato Fosfatase/genética , Neurônios Motores/metabolismo , Neurônios Motores/fisiologia , Camundongos , Ácidos Fosfatídicos/metabolismo , Células Receptoras Sensoriais/metabolismo , Feminino , Tratos Piramidais/metabolismo , Tratos Piramidais/patologiaRESUMO
Any electrical signal propagating in a metallic conductor loses amplitude due to the natural resistance of the metal. Compensating for such losses presently requires repeatedly breaking the conductor and interposing amplifiers that consume and regenerate the signal. This century-old primitive severely constrains the design and performance of modern interconnect-dense chips1. Here we present a fundamentally different primitive based on semi-stable edge of chaos (EOC)2,3, a long-theorized but experimentally elusive regime that underlies active (self-amplifying) transmission in biological axons4,5. By electrically accessing the spin crossover in LaCoO3, we isolate semi-stable EOC, characterized by small-signal negative resistance and amplification of perturbations6,7. In a metallic line atop a medium biased at EOC, a signal input at one end exits the other end amplified, without passing through a separate amplifying component. While superficially resembling superconductivity, active transmission offers controllably amplified time-varying small-signal propagation at normal temperature and pressure, but requires an electrically energized EOC medium. Operando thermal mapping reveals the mechanism of amplification-bias energy of the EOC medium, instead of fully dissipating as heat, is partly used to amplify signals in the metallic line, thereby enabling spatially continuous active transmission, which could transform the design and performance of complex electronic chips.
Assuntos
Axônios , Axônios/fisiologia , Temperatura , Animais , Modelos Neurológicos , Condutividade Elétrica , SupercondutividadeRESUMO
Computer haptics (CH) is about integration of tactile sensation and rendering in Metaverse. However, unlike computer vision (CV) where both hardware infrastructure and software programs are well developed, a generic tactile data capturing device that serves the same role as what a camera does for CV, is missing. Bioinspired by electrophysiological processes in human tactile somatosensory nervous system, here we propose a tactile scanner along with a neuromorphically-engineered system, in which a closed-loop tactile acquisition and rendering (re-creation) are preliminarily achieved. Based on the architecture of afferent nerves and intelligent functions of mechano-gating and leaky integrate-and-fire models, such a tactile scanner is designed and developed by using piezoelectric transducers as axon neurons and thin film transistor (TFT)-based neuromorphic circuits to mimic synaptic behaviours and neural functions. As an example, the neuron-like tactile information of surface textures is captured and further used to render the texture friction of a virtual surface for "recreating" a "true" feeling of touch.
Assuntos
Tato , Humanos , Tato/fisiologia , Percepção do Tato/fisiologia , Neurônios/fisiologia , Axônios/fisiologiaRESUMO
The in vivo three-dimensional genomic architecture of adult mature neurons at homeostasis and after medically relevant perturbations such as axonal injury remains elusive. Here, we address this knowledge gap by mapping the three-dimensional chromatin architecture and gene expression program at homeostasis and after sciatic nerve injury in wild-type and cohesin-deficient mouse sensory dorsal root ganglia neurons via combinatorial Hi-C, promoter-capture Hi-C, CUT&Tag for H3K27ac and RNA-seq. We find that genes involved in axonal regeneration form long-range, complex chromatin loops, and that cohesin is required for the full induction of the regenerative transcriptional program. Importantly, loss of cohesin results in disruption of chromatin architecture and severely impaired nerve regeneration. Complex enhancer-promoter loops are also enriched in the human fetal cortical plate, where the axonal growth potential is highest, and are lost in mature adult neurons. Together, these data provide an original three-dimensional chromatin map of adult sensory neurons in vivo and demonstrate a role for cohesin-dependent long-range promoter interactions in nerve regeneration.
Assuntos
Axônios , Cromatina , Coesinas , Regeneração Nervosa , Regiões Promotoras Genéticas , Células Receptoras Sensoriais , Animais , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/fisiologia , Camundongos , Regiões Promotoras Genéticas/genética , Cromatina/metabolismo , Regeneração Nervosa/genética , Regeneração Nervosa/fisiologia , Axônios/metabolismo , Axônios/fisiologia , Humanos , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Cromossômicas não Histona/genética , Elementos Facilitadores Genéticos/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Gânglios Espinais/metabolismo , Gânglios Espinais/citologia , Nervo Isquiático/metabolismoRESUMO
Recent studies highlighted the role of platelet-rich plasma (PRP) in progenitor cell homing, migration, and nerve cell regeneration while also inhibiting fibrosis and apoptosis in cavernous nerve injury (CNI). The aim of this study was to investigate the effect of PRP administration on axon and collagen regeneration in CNI. A true experimental study using a post-test-only control group design was conducted. Twenty-five male Wistar rats (Rattus norvegicus), weighing 200-300 grams, were divided into five groups: two control groups (sham procedure and negative control), and three experimental groups receiving local PRP, intraperitoneal PRP, and a combination of local and intraperitoneal PRP. The cavernous nerve was injured with a hemostasis clamp for one minute before 200 µL of 200 PRP was injected locally, intraperitoneally, or both, depending on the group. After four weeks, the rats were euthanized, tissue segments (2 mm) from each cavernous nerve and mid-penis were collected and analyzed for collagen density, axon diameter, and number of myelinated axons. Our study found that collagen growth was slower in CNI group without PRP (sham procedure) compared to all PRP groups (local, intraperitoneal, and combination). The intraperitoneal PRP group had the highest collagen density at 5.62 µm; however, no significant difference was observed in collagen density among all groups (p=0.056). Similar axon diameter was found across the groups, with no statistically significant difference observed (p=0.856). In the number of myelinated axons, a significant difference was found among all groups with significantly more axons in local PRP and combined local and intraperitoneal PRP groups compared to others (p=0.026). In conclusion, PRP administration improved the number of myelinated axons in CNI, suggesting PRP role in CNI regeneration and the potential for an innovative approach to treating erectile dysfunction associated with CNI.
Assuntos
Axônios , Colágeno , Disfunção Erétil , Regeneração Nervosa , Pênis , Plasma Rico em Plaquetas , Ratos Wistar , Animais , Masculino , Colágeno/metabolismo , Ratos , Regeneração Nervosa/efeitos dos fármacos , Regeneração Nervosa/fisiologia , Axônios/fisiologia , Axônios/patologia , Axônios/efeitos dos fármacos , Pênis/inervação , Pênis/efeitos dos fármacos , Disfunção Erétil/terapia , Disfunção Erétil/tratamento farmacológico , Modelos Animais de Doenças , Traumatismos dos Nervos Periféricos/terapiaRESUMO
Most neurons are not replaced after injury and thus possess robust intrinsic mechanisms for repair after damage. Axon injury triggers a calcium wave, and calcium and cAMP can augment axon regeneration. In comparison to axon regeneration, dendrite regeneration is poorly understood. To test whether calcium and cAMP might also be involved in dendrite injury signaling, we tracked the responses of Drosophila dendritic arborization neurons to laser severing of axons and dendrites. We found that calcium and subsequently cAMP accumulate in the cell body after both dendrite and axon injury. Two voltage-gated calcium channels (VGCCs), L-Type and T-Type, are required for the calcium influx in response to dendrite injury and play a role in rapid initiation of dendrite regeneration. The AC8 family adenylyl cyclase, Ac78C, is required for cAMP production after dendrite injury and timely initiation of regeneration. Injury-induced cAMP production is sensitive to VGCC reduction, placing calcium upstream of cAMP generation. We propose that two VGCCs initiate global calcium influx in response to dendrite injury followed by production of cAMP by Ac78C. This signaling pathway promotes timely initiation of dendrite regrowth several hours after dendrite damage.
Assuntos
Adenilil Ciclases , Canais de Cálcio Tipo L , Cálcio , AMP Cíclico , Dendritos , Animais , Adenilil Ciclases/metabolismo , Adenilil Ciclases/genética , Axônios/metabolismo , Axônios/fisiologia , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Canais de Cálcio/genética , Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo L/genética , Canais de Cálcio Tipo T/metabolismo , Canais de Cálcio Tipo T/genética , Sinalização do Cálcio/genética , AMP Cíclico/metabolismo , Dendritos/metabolismo , Drosophila/genética , Drosophila melanogaster/genética , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Regeneração Nervosa/fisiologia , Regeneração Nervosa/genética , Neurônios/metabolismo , Regeneração/genética , Regeneração/fisiologia , Transdução de SinaisRESUMO
The development of the visual system is a complex and multistep process characterized by the precise wiring of retinal ganglion cell (RGC) axon terminals with their corresponding neurons in the visual nuclei of the brain. Upon reaching primary image-forming nuclei (IFN), such as the superior colliculus and the lateral geniculate nucleus, RGC axons undergo extensive arborization that refines over the first few postnatal weeks. The molecular mechanisms driving this activity-dependent remodeling process, which is influenced by waves of spontaneous activity in the developing retina, are still not well understood. In this study, by manipulating the activity of RGCs in mice from either sex and analyzing their transcriptomic profiles before eye-opening, we identified the Type I membrane protein synaptotagmin 13 (Syt13) as involved in spontaneous activity-dependent remodeling. Using these mice, we also explored the impact of spontaneous retinal activity on the development of other RGC recipient targets such as nonimage-forming (NIF) nuclei and demonstrated that proper frequency and duration of retinal waves occurring prior to visual experience are essential for shaping the connectivity of the NIF circuit. Together, these findings contribute to a deeper understanding of the molecular and physiological mechanisms governing activity-dependent axon refinement during the assembly of the visual circuit.
Assuntos
Axônios , Retina , Células Ganglionares da Retina , Vias Visuais , Animais , Células Ganglionares da Retina/fisiologia , Camundongos , Axônios/fisiologia , Vias Visuais/fisiologia , Vias Visuais/crescimento & desenvolvimento , Feminino , Masculino , Retina/crescimento & desenvolvimento , Retina/fisiologia , Colículos Superiores/fisiologia , Colículos Superiores/crescimento & desenvolvimento , Colículos Superiores/citologia , Camundongos Endogâmicos C57BL , Corpos Geniculados/fisiologia , Corpos Geniculados/crescimento & desenvolvimento , Animais Recém-NascidosRESUMO
Neurodegenerative disorders, including traumatic injuries to the central nervous system (CNS) and neurodegenerative diseases, are characterized by early axonal damage, which does not regenerate in the adult mammalian CNS, leading to permanent neurological deficits. One of the primary causes of the loss of regenerative ability is thought to be a developmental decline in neurons' intrinsic capability for axon growth. Different molecules are involved in the developmental loss of the ability for axon regeneration, including many transcription factors. However, the function of microRNAs (miRNAs), which are also modulators of gene expression, in axon re-growth is still unclear. Among the various miRNAs recently identified with roles in the CNS, miR-17, which is highly expressed during early development, emerges as a promising target to promote axon regeneration. Here, we used adeno-associated viral (AAV) vectors to overexpress miR-17 (AAV.miR-17) in primary cortical neurons and evaluate its effects on neurite and axon regeneration in vitro. Although AAV.miR-17 had no significant effect on neurite outgrowth and arborization, it significantly enhances neurite regeneration after scratch lesion and axon regeneration after axotomy of neurons cultured in microfluidic chambers. Target prediction and functional annotation analyses suggest that miR-17 regulates gene expression associated with autophagy and cell metabolism. Our findings suggest that miR-17 promotes regenerative response and thus could mitigate neurodegenerative effects.
Assuntos
Axônios , Dependovirus , MicroRNAs , Regeneração Nervosa , Neuritos , MicroRNAs/genética , MicroRNAs/metabolismo , Animais , Axônios/metabolismo , Axônios/fisiologia , Regeneração Nervosa/genética , Neuritos/metabolismo , Dependovirus/genética , Células Cultivadas , Vetores Genéticos/genética , Camundongos , Neurônios/metabolismoRESUMO
Regeneration of sensory axons after a burn injury depends on early keratinocyte responses regulated by the wound microenvironment.
Assuntos
Axônios , Queimaduras , Regeneração Nervosa , Axônios/fisiologia , Regeneração Nervosa/fisiologia , Animais , Humanos , Queratinócitos/fisiologia , Cicatrização/fisiologiaRESUMO
Investigating and understanding the biomechanical kinematics and kinetics of human brain axonal fibers during head impact process is crucial to study the mechanisms of Traumatic Axonal Injury (TAI). Such a study may require the explicit incorporation of brain fiber tracts into the host brain in order to distinguish the mechanical states of axonal fibers and brain tissue. Herein we extend our previously developed human head model by using an embedded element method to include fiber tracts reconstructed from diffusion tensor images in a host brain with the purpose of numerically tracking the deformation state of axonal fiber tracts during a head impact simulation. The updated model is validated by comparing its prediction of intracranial pressures with experimental data, followed by a thorough study of the effects of element types used for fiber tracts and the stiffness ratios of fiber to host brain. The validated model is also used to predict and visualize the damaged region of fiber tracts during the head impact process based on different injury criteria. The model is promising in tracking the state of fiber tracts and can add more objective functions such as axonal fiber deformation if used in the future design optimization of head protective equipment such as a football helmet.
Assuntos
Axônios , Encéfalo , Análise de Elementos Finitos , Humanos , Axônios/fisiologia , Modelos Neurológicos , Fenômenos Biomecânicos/fisiologia , Imagem de Tensor de Difusão , Simulação por ComputadorRESUMO
We developed a rat dorsal root ganglion (DRG)-derived sensory nerve organotypic model by culturing DRG explants on an organoid culture device. With this method, a large number of organotypic cultures can be produced simultaneously with high reproducibility simply by seeding DRG explants derived from rat embryos. Unlike previous DRG explant models, this organotypic model consists of a ganglion and an axon bundle with myelinated A fibers, unmyelinated C fibers, and stereo-myelin-forming nodes of Ranvier. The model also exhibits Ca2+ signaling in cell bodies in response to application of chemical stimuli to nerve terminals. Further, axonal transection increases the activating transcription factor 3 mRNA level in ganglia. Axons and myelin are shown to regenerate 14 days following transection. Our sensory organotypic model enables analysis of neuronal excitability in response to pain stimuli and tracking of morphological changes in the axon bundle over weeks.
Assuntos
Axônios , Gânglios Espinais , Sistemas Microfisiológicos , Animais , Ratos , Fator 3 Ativador da Transcrição , Axônios/fisiologia , Axônios/metabolismo , Sinalização do Cálcio , Gânglios Espinais/citologia , Gânglios Espinais/metabolismo , Bainha de Mielina/fisiologia , Bainha de Mielina/metabolismo , Organoides/metabolismo , Nervos Periféricos/metabolismo , Ratos Sprague-Dawley , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/fisiologiaRESUMO
BACKGROUND: This study investigates the potential of transcranial magnetic stimulation (TMS) to enhance spinal cord axon regeneration by modulating corticospinal pathways and improving motor nerve function recovery in rats with spinal cord injury (SCI). NEW METHOD: TMS is a non-invasive neuromodulation technique that generates a magnetic field to activate neurons in the brain, leading to depolarization and modulation of cortical activity. Initially utilized for brain physiology research, TMS has evolved into a diagnostic and prognostic tool in clinical settings, with increasing interest in its therapeutic applications. However, its potential for treating motor dysfunction in SCI has been underexplored. RESULTS: The TMS intervention group exhibited significant improvements compared to the control group across behavioral assessments, neurophysiological measurements, pathological analysis, and immunological markers. COMPARISON WITH EXISTING METHODS: Unlike most studies that focus on localized spinal cord injury or muscle treatments, this study leverages the non-invasive, painless, and highly penetrating nature of TMS to focus on the corticospinal tracts, exploring its therapeutic potential for SCI. CONCLUSIONS: TMS enhances motor function recovery in rats with SCI by restoring corticospinal pathway integrity and promoting axonal regeneration. These findings highlight TMS as a promising therapeutic option for SCI patients with currently limited treatment alternatives.