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
Successful axonal regeneration following injury requires the effective allocation of energy. How axons withstand the initial disruption in mitochondrial energy production caused by the injury and subsequently initiate regrowth is poorly understood. Transcriptomic data showed increased expression of glycolytic genes after optic nerve crush in retinal ganglion cells with the co-deletion of Pten and Socs3. Using retinal cultures in a multicompartment microfluidic device, we observed increased regrowth and enhanced mitochondrial trafficking in the axons of Pten and Socs3 co-deleted neurons. While wild-type axons relied on mitochondrial metabolism, after injury, in the absence of Pten and Socs3, energy production was supported by local glycolysis. Specific inhibition of lactate production hindered injury survival and the initiation of regrowth while slowing down glycolysis upstream impaired regrowth initiation, axonal elongation, and energy production. Together, these observations reveal that glycolytic ATP, combined with sustained mitochondrial transport, is essential for injury-induced axonal regrowth, providing new insights into the metabolic underpinnings of axonal regeneration.
Assuntos
Axônios , Glicólise , Mitocôndrias , Regeneração Nervosa , Células Ganglionares da Retina , Animais , Axônios/metabolismo , Regeneração Nervosa/genética , Células Ganglionares da Retina/metabolismo , Células Ganglionares da Retina/patologia , Mitocôndrias/metabolismo , Mitocôndrias/genética , Camundongos , Traumatismos do Nervo Óptico/metabolismo , Traumatismos do Nervo Óptico/patologia , Traumatismos do Nervo Óptico/genética , PTEN Fosfo-Hidrolase/metabolismo , PTEN Fosfo-Hidrolase/genética , Camundongos Endogâmicos C57BL , Trifosfato de Adenosina/metabolismo , Metabolismo Energético/genéticaRESUMO
Rationale: Spinal cord injury (SCI)-induced vascular damage causes ischemia and hypoxia at the injury site, which, in turn, leads to profound metabolic disruptions. The effects of these metabolic alterations on neural tissue remodeling and functional recovery have yet to be elucidated. The current study aimed to investigate the consequences of the SCI-induced hypoxic environment at the epicenter of the injury. Methods: This study employed metabolomics to assess changes in energy metabolism after SCI. The use of a lactate sensor identified lactate shuttle between endothelial cells (ECs) and neurons. Reanalysis of single-cell RNA sequencing data demonstrated reduced MCT1 expression in ECs after SCI. Additionally, an adeno-associated virus (AAV) overexpressing MCT1 was utilized to elucidate its role in endothelial-neuronal interactions, tissue repair, and functional recovery. Results: The findings revealed markedly decreased monocarboxylate transporter 1 (MCT1) expression that facilitates lactate delivery to neurons to support their energy metabolism in ECs post-SCI. This decreased expression of MCT1 disrupts lactate transport to neurons, resulting in a metabolic imbalance that impedes axonal regeneration. Strikingly, our results suggested that administering adeno-associated virus specifically to ECs to restore MCT1 expression enhances axonal regeneration and improves functional recovery in SCI mice. These findings indicate a novel link between lactate shuttling from endothelial cells to neurons following SCI and subsequent neural functional recovery. Conclusion: In summary, the current study highlights a novel metabolic pathway for therapeutic interventions in the treatment of SCI. Additionally, our findings indicate the potential benefits of targeting lactate transport mechanisms in recovery from SCI.
Assuntos
Axônios , Células Endoteliais , Ácido Láctico , Transportadores de Ácidos Monocarboxílicos , Traumatismos da Medula Espinal , Simportadores , Traumatismos da Medula Espinal/metabolismo , Animais , Transportadores de Ácidos Monocarboxílicos/metabolismo , Transportadores de Ácidos Monocarboxílicos/genética , Células Endoteliais/metabolismo , Ácido Láctico/metabolismo , Camundongos , Axônios/metabolismo , Simportadores/metabolismo , Simportadores/genética , Recuperação de Função Fisiológica/fisiologia , Dependovirus/genética , Regeneração Nervosa , Neurônios/metabolismo , Metabolismo Energético , Camundongos Endogâmicos C57BL , Feminino , Modelos Animais de Doenças , HumanosRESUMO
Basal forebrain cholinergic neurons (BFCNs) extend long projections to multiple regions in the brain to regulate cognitive functions. Degeneration of BFCNs is seen with aging, after brain injury, and in neurodegenerative disorders. An increase in the amount of the immature proform of nerve growth factor (proNGF) in the cerebral cortex results in retrograde degeneration of BFCNs through activation of proNGF receptor p75NTR. Here, we investigated the signaling cascades initiated at the axon terminal that mediate proNGF-induced retrograde degeneration. We found that local axonal protein synthesis and retrograde transport mediated proNGF-induced degeneration initiated from the axon terminal. Analysis of the nascent axonal proteome revealed that proNGF stimulation of axonal terminals triggered the synthesis of numerous proteins within the axon, and pathway analysis showed that amyloid precursor protein (APP) was a key upstream regulator in cultured BFCNs and in mice. Our findings reveal a functional role for APP in mediating BFCN axonal degeneration and cell death induced by proNGF.
Assuntos
Precursor de Proteína beta-Amiloide , Axônios , Prosencéfalo Basal , Fator de Crescimento Neural , Animais , Precursor de Proteína beta-Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/genética , Axônios/metabolismo , Axônios/patologia , Fator de Crescimento Neural/metabolismo , Fator de Crescimento Neural/genética , Prosencéfalo Basal/metabolismo , Prosencéfalo Basal/patologia , Camundongos , Receptores de Fator de Crescimento Neural/metabolismo , Receptores de Fator de Crescimento Neural/genética , Precursores de Proteínas/metabolismo , Precursores de Proteínas/genética , Neurônios Colinérgicos/metabolismo , Neurônios Colinérgicos/patologia , Degeneração Neural/metabolismo , Degeneração Neural/patologia , Camundongos Endogâmicos C57BL , Células Cultivadas , Transdução de SinaisRESUMO
Glaucoma is a blinding disease where the retinal ganglion cells and their axons degenerate. Degradation of axonal microtubules is thought to play a critical role in the pathogenesis, but the mechanism is unknown. Here we investigate whether microtubule disruption in glaucoma can be alleviated by metabolic rescue. The integrity of axonal microtubules and the morphology of the retinal nerve fibers were evaluated by second-harmonic generation microscopy in a mouse model of glaucoma, DBA/2J, which received a dietary supplement of nicotinamide (NAM) for reducing metabolic stress. It was compared with control DBA/2J, which did not receive NAM, and non-glaucomatous DBA/2J-Gpnmb+. We found that the morphology of the retinal nerve fibers, but not axonal microtubules, are significantly protected by NAM. The decoupling is analogous to microtubule deficit, a glaucoma pathology in which axonal microtubules exhibit rapid degradation compared to the morphology of the retinal nerve fibers. Understanding microtubule deficit could provide insights into the divergent responses to NAM. From co-registered images of second-harmonic generation and immunofluorescence, it was determined that microtubule deficit was not due to a shortage of tubulins. Furthermore, microtubule deficit colocalized with the sectors in which the retinal ganglion cells were disconnected from the brain, suggesting that microtubule disruption is associated with axonal transport deficit in glaucoma. Together, our data suggests significant role axonal microtubules play in glaucomatous degeneration, offering a new opportunity for neuroprotection.
Assuntos
Modelos Animais de Doenças , Glaucoma , Camundongos Endogâmicos DBA , Microtúbulos , Niacinamida , Células Ganglionares da Retina , Animais , Glaucoma/patologia , Glaucoma/metabolismo , Glaucoma/tratamento farmacológico , Niacinamida/farmacologia , Niacinamida/uso terapêutico , Camundongos , Células Ganglionares da Retina/efeitos dos fármacos , Células Ganglionares da Retina/patologia , Células Ganglionares da Retina/metabolismo , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Axônios/efeitos dos fármacos , Axônios/metabolismo , Axônios/patologia , Microscopia/métodos , Fibras Nervosas/efeitos dos fármacos , Fibras Nervosas/patologia , Fibras Nervosas/metabolismoRESUMO
Traumatic brain injury (TBI) affects millions globally, with a majority of TBI cases being classified as mild, in which diffuse pathologies prevail. Two of the pathological hallmarks of TBI are diffuse axonal injury (DAI) and microglial activation. While progress has been made investigating the breadth of TBI-induced axonal injury and microglial changes in rodents, the neuroinflammatory progression and interaction between microglia and injured axons in humans is less well understood. Our group previously investigated microglial process convergence (MPC), in which processes of non-phagocytic microglia directly contact injured proximal axonal swellings, in rats and micropigs acutely following TBI. These studies demonstrated that MPC occurred on injured axons in the micropig, but not in the rat, following diffuse TBI. While it has been shown that microglia co-exist and interact with injured axons in humans post-TBI, the occurrence of MPC has not been quantitatively measured in the human brain. Therefore, in the current study we sought to validate our pig findings in human postmortem tissue. We investigated MPC onto injured axonal swellings and intact myelinated fibers in cases from individuals with confirmed DAI and control human brain tissue using multiplex immunofluorescent histochemistry. We found an increase in MPC onto injured axonal swellings, consistent with our previous findings in micropigs, indicating that MPC is a clinically relevant phenomenon that warrants further investigation.
Assuntos
Axônios , Lesão Axonal Difusa , Microglia , Humanos , Microglia/patologia , Microglia/metabolismo , Axônios/patologia , Axônios/metabolismo , Animais , Masculino , Suínos , Lesão Axonal Difusa/patologia , Lesão Axonal Difusa/metabolismo , Feminino , Encéfalo/patologia , Encéfalo/metabolismo , Lesões Encefálicas Traumáticas/patologia , Lesões Encefálicas Traumáticas/metabolismo , Pessoa de Meia-Idade , Autopsia , Adulto , Idoso , RatosRESUMO
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: Spinal cord injury (SCI) often leads to a loss of motor and sensory function. Axon regeneration and outgrowth are key events for functional recovery after spinal cord injury. Endogenous growth of axons is associated with a variety of factors. Inspired by the relationship between developing nerves and blood vessels, we believe spinal cord-derived microvascular endothelial cells (SCMECs) play an important role in axon growth. RESULTS: We found SCMECs could promote axon growth when co-cultured with neurons in direct and indirect co-culture systems via downregulating the miR-323-5p expression of neurons. In rats with spinal cord injury, neuron-targeting nanoparticles were employed to regulate miR-323-5p expression in residual neurons and promote function recovery. CONCLUSIONS: Our study suggests that SCMEC can promote axon outgrowth by downregulating miR-323-5p expression within neurons, and miR-323-5p could be selected as a potential target for spinal cord injury repair.
Assuntos
Axônios , Técnicas de Cocultura , Células Endoteliais , MicroRNAs , Ratos Sprague-Dawley , Traumatismos da Medula Espinal , Medula Espinal , Animais , MicroRNAs/metabolismo , MicroRNAs/genética , Células Endoteliais/metabolismo , Ratos , Medula Espinal/metabolismo , Axônios/metabolismo , Neurônios/metabolismo , Células Cultivadas , Nanopartículas/química , Regeneração Nervosa , FemininoRESUMO
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-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) is an adult-onset, inherited white matter disorder encompassing two previously identified clinicopathologically similar entities: pigmentary orthochromatic leukodystrophy (POLD) and hereditary diffuse leukoencephalopathy with spheroids (HDLS). In this chapter, we discuss how advances in our genetic understanding of the condition have further delineated three distinct clinical entities within ALSP, namely CSF1R-related ALSP, AARS2-related leukoencephalopathy (AARS2-L), and AARS (HDLS-S). We provide descriptions of the clinical, radiologic, pathologic, and pathophysiologic findings in each entity, detailing their similarities and differences, and discuss current and future treatment options where available.
Assuntos
Leucoencefalopatias , Neuroglia , Humanos , Leucoencefalopatias/genética , Leucoencefalopatias/patologia , Neuroglia/patologia , Adulto , Axônios/patologiaRESUMO
Rotenone is a mitochondrial complex I inhibitor that causes retinal degeneration. A study of a rat model of rotenone-induced retinal degeneration suggested that this model is caused by indirect postsynaptic N-methyl-D-aspartate (NMDA) stimulation triggered by oxidative stress-mediated presynaptic intracellular calcium signaling. To elucidate the mechanisms by which rotenone causes axonal degeneration, we investigated morphological changes in optic nerves and the change in retinal ganglion cell (RGC) number in rats. Optic nerves and retinas were collected 3 and 7 days after the intravitreal injection of rotenone. The cross-sections of the optic nerves were subjected to a morphological analysis with axon quantification. The axons and somas of RGCs were analyzed immunohistochemically in retinal flatmounts. In the optic nerve, rotenone induced axonal swelling and degeneration with the incidence of reactive gliosis. Rotenone also significantly reduced axon numbers in the optic nerve. Furthermore, rotenone caused axonal thinning, fragmentation, and beading in RGCs on flatmounts and decreased the number of RGC soma. In conclusion, the intravitreal injection of rotenone in rats induced morphological abnormities with a reduced number of optic nerve axons and RGC axons when the RGC somas were degenerated. These findings help elucidate the pathogenesis of optic neuropathy induced by mitochondrial dysfunction.
Assuntos
Axônios , Traumatismos do Nervo Óptico , Células Ganglionares da Retina , Rotenona , Animais , Rotenona/toxicidade , Rotenona/efeitos adversos , Células Ganglionares da Retina/patologia , Células Ganglionares da Retina/efeitos dos fármacos , Células Ganglionares da Retina/metabolismo , Ratos , Masculino , Axônios/patologia , Axônios/efeitos dos fármacos , Axônios/metabolismo , Traumatismos do Nervo Óptico/patologia , Traumatismos do Nervo Óptico/induzido quimicamente , Traumatismos do Nervo Óptico/metabolismo , Nervo Óptico/patologia , Nervo Óptico/efeitos dos fármacos , Nervo Óptico/metabolismo , Ratos Sprague-Dawley , Injeções IntravítreasRESUMO
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
Purpose: To evaluate the effectiveness of surgical reversal of experimental optic nerve compression in treating persistent compressive optic neuropathy and to explore the relationship between surgical outcomes and the timing of the procedure. Methods: Surgical reversal procedures (decompression surgery) were conducted at five time intervals: 1, 3, and 7 days and 2 and 3 weeks following optic nerve compression in a rabbit model. The groups were labeled as DC-1d, DC-3d, DC-7d, DC-2w, and DC-3w, respectively. The study investigated changes in ganglion cell complex (GCC) thickness using spectral-domain optical coherence tomography and the percentage of surviving retinal ganglion cells (RGCs) through immunofluorescence staining and optic nerve axons stained with p-phenylenediamine at 4 weeks after decompression. Additionally, the area distribution of surviving axons was analyzed. Results: The decline in GCC thickness was halted following decompression. The remaining thickness of the GCC in group DC-1d was found to be statistically significantly higher at 2, 3, and 4 weeks postonset compared to the no-decompression group. Similarly, GCC thickness in group DC-3d was significantly higher at 3 and 4 weeks postonset. The percentage of surviving RGCs and axons at 4 weeks postonset exhibited an exponential correlation with the onset time of decompression, with R2 values of 0.72 and 0.78, respectively. The surviving axon area declined following delayed decompression. Conclusions: Persistent substantial compression on the optic nerve leads to exponential degeneration of the optic nerve, initially affecting larger optic nerve fibers. Early intervention aimed at relieving the compression on the optic nerve may offer potential benefits in mitigating the degenerative effects and conserving visual function.
Assuntos
Descompressão Cirúrgica , Modelos Animais de Doenças , Síndromes de Compressão Nervosa , Fibras Nervosas , Doenças do Nervo Óptico , Nervo Óptico , Células Ganglionares da Retina , Tomografia de Coerência Óptica , Animais , Coelhos , Células Ganglionares da Retina/patologia , Descompressão Cirúrgica/métodos , Fibras Nervosas/patologia , Doenças do Nervo Óptico/cirurgia , Doenças do Nervo Óptico/etiologia , Síndromes de Compressão Nervosa/cirurgia , Síndromes de Compressão Nervosa/etiologia , Nervo Óptico/cirurgia , Nervo Óptico/patologia , Axônios/patologia , Masculino , Degeneração Neural/cirurgia , Degeneração Neural/patologiaRESUMO
Myelination of axons is a key determinant of fast action potential propagation, axonal health and circuit function. Previously considered a static structure, it is now clear that myelin is dynamically regulated in response to neuronal activity in the central nervous system (CNS). However, how activity-dependent signals are conveyed to oligodendrocytes remains unclear. Here, we review the potential mechanisms by which neurons could communicate changing activity levels to myelin, with a focus on the accumulating body of evidence to support activity-dependent vesicular signalling directly onto myelin sheaths. We discuss recent in vivo findings of activity-dependent fusion of neurotransmitter vesicles from non-synaptic axonal sites, and how modulation of this vesicular fusion regulates the stability and growth of myelin sheaths. We also consider the potential mechanisms by which myelin could sense and respond to axon-derived signals to initiate remodelling, and the relevance of these adaptations for circuit function. We propose that axonal vesicular signalling represents an important and underappreciated mode of communication by which neurons can transmit activity-regulated signals to myelinating oligodendrocytes and, potentially, more broadly to other cell types in the CNS.
Assuntos
Axônios , Bainha de Mielina , Neurotransmissores , Bainha de Mielina/metabolismo , Axônios/metabolismo , Animais , Humanos , Neurotransmissores/metabolismo , Transmissão Sináptica , Oligodendroglia/metabolismo , Transdução de Sinais , Vesículas Sinápticas/metabolismo , Neurônios/metabolismoRESUMO
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
Neurons in the cortex are heterogeneous, sending diverse axonal projections to multiple brain regions. Unraveling the logic of these projections requires single-neuron resolution. Although a growing number of techniques have enabled high-throughput reconstruction, these techniques are typically limited to dozens or at most hundreds of neurons per brain, requiring that statistical analyses combine data from different specimens. Here we present axonal BARseq, a high-throughput approach based on reading out nucleic acid barcodes using in situ RNA sequencing, which enables analysis of even densely labeled neurons. As a proof of principle, we have mapped the long-range projections of >8000 primary auditory cortex neurons from a single male mouse. We identified major cell types based on projection targets and axonal trajectory. The large sample size enabled us to systematically quantify the projections of intratelencephalic (IT) neurons, and revealed that individual IT neurons project to different layers in an area-dependent fashion. Axonal BARseq is a powerful technique for studying the heterogeneity of single neuronal projections at high throughput within individual brains.