RESUMEN
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode (MELAS) syndrome, caused by a single base substitution in mitochondrial DNA (m.3243A>G), is one of the most common maternally inherited mitochondrial diseases accompanied by neuronal damage due to defects in the oxidative phosphorylation system. There is no established treatment. Our previous study reported a superior restoration of mitochondrial function and bioenergetics in mitochondria-deficient cells using highly purified mesenchymal stem cells (RECs). However, whether such exogenous mitochondrial donation occurs in mitochondrial disease models and whether it plays a role in the recovery of pathological neuronal functions is unknown. Here, utilizing induced pluripotent stem cells (iPSC), we differentiated neurons with impaired mitochondrial function from patients with MELAS. MELAS neurons and RECs/mesenchymal stem cells (MSCs) were cultured under contact or non-contact conditions. Both RECs and MSCs can donate mitochondria to MELAS neurons, but RECs are more excellent than MSCs for mitochondrial transfer in both systems. In addition, REC-mediated mitochondrial transfer significantly restored mitochondrial function, including mitochondrial membrane potential, ATP/ROS production, intracellular calcium storage, and oxygen consumption rate. Moreover, mitochondrial function was maintained for at least three weeks. Thus, REC-donated exogenous mitochondria might offer a potential therapeutic strategy for treating neurological dysfunction in MELAS.
Asunto(s)
Acidosis Láctica , Síndrome MELAS , Células Madre Mesenquimatosas , Enfermedades Mitocondriales , Humanos , Síndrome MELAS/genética , Síndrome MELAS/terapia , Mitocondrias/genética , Acidosis Láctica/metabolismo , Acidosis Láctica/patología , ADN Mitocondrial/metabolismo , Enfermedades Mitocondriales/metabolismo , Neuronas/patología , Células Madre Mesenquimatosas/metabolismoRESUMEN
The peroxisome is a subcellular organelle that functions in essential metabolic pathways, including biosynthesis of plasmalogens, fatty acid ß-oxidation of very-long-chain fatty acids, and degradation of hydrogen peroxide. Peroxisome biogenesis disorders (PBDs) manifest as severe dysfunction in multiple organs, including the central nervous system (CNS), but the pathogenic mechanisms in PBDs are largely unknown. Because CNS integrity is coordinately established and maintained by neural cell interactions, we here investigated whether cell-cell communication is impaired and responsible for the neurological defects associated with PBDs. Results from a noncontact co-culture system consisting of primary hippocampal neurons with glial cells revealed that a peroxisome-deficient astrocytic cell line secretes increased levels of brain-derived neurotrophic factor (BDNF), resulting in axonal branching of the neurons. Of note, the BDNF expression in astrocytes was not affected by defects in plasmalogen biosynthesis and peroxisomal fatty acid ß-oxidation in the astrocytes. Instead, we found that cytosolic reductive states caused by a mislocalized catalase in the peroxisome-deficient cells induce the elevation in BDNF secretion. Our results suggest that peroxisome deficiency dysregulates neuronal axogenesis by causing a cytosolic reductive state in astrocytes. We conclude that astrocytic peroxisomes regulate BDNF expression and thereby support neuronal integrity and function.
Asunto(s)
Astrocitos/metabolismo , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Neuronas/metabolismo , Trastorno Peroxisomal/metabolismo , Peroxisomas/metabolismo , Animales , Células CHO , Línea Celular , Línea Celular Tumoral , Células Cultivadas , Cricetinae , Cricetulus , Citosol/metabolismo , Ácidos Grasos/metabolismo , Hipocampo/citología , Humanos , Oxidación-Reducción , Plasmalógenos/metabolismo , Ratas , Ratas Wistar , Regulación hacia ArribaRESUMEN
Neurons of the parabrachial nucleus (PB) receive nociceptive input from the dorsal horn (DH) of the spinal cord and caudal part of the spinal trigeminal nucleus (Vc). Previously, we demonstrated that glutamatergic lateral PB neurons innervate orexin (ORX) neurons in the perifornical area (PeF) of the hypothalamus. However, the neural circuit via which ORX neurons receive nociceptive input from the DH and brainstem remains to be determined. In the present study, we aimed to clarify the potential nociceptive circuit from DH/Vc to PeF via lateral PB. We first examined the neuronal activity of fluorogold (FG)-labeled, PeF-projecting lateral PB neurons in Wistar rats following either saline or formalin injection to the forepaw or lips. We clearly detected more abundant c-Fos-positive, FG-labeled neurons in the PB nucleus. To investigate the relay from the DH/Vc to the PeF via the lateral PB, we injected FG into the PeF and biotinylated dextranamine (BDA) into the contralateral DH or ipsilateral Vc. We observed the most prominent overlap between BDA-labeled axon terminals and FG-labeled neurons in the dorsal lateral and central lateral subnuclei. Furthermore, we found that FG-labeled neurons formed close contact sites with BDA-labeled axons with synaptophysin immunoreactivity. Using electron microscopy, we confirmed that these contact sites were truly synapses. Taken together, our results indicate that the DH/Vc transmits nociceptive information to the PeF via the lateral PB, suggesting the involvement of ORX neurons in the pain pathway.
Asunto(s)
Hipotálamo/fisiología , Vías Nerviosas , Nociceptores/fisiología , Núcleos Parabraquiales/fisiología , Médula Espinal/fisiología , Núcleo Espinal del Trigémino/fisiología , Animales , Masculino , Red Nerviosa , Ratas WistarRESUMEN
Chondroitin sulfate proteoglycans (CSPGs) are a major component of glial scars, inhibiting axonal growth in the central nervous system. Protein tyrosine phosphatase, receptor type S (PTPσ) has been identified as a receptor for CSPGs, whereas its downstream signaling pathway remains to be fully understood. Here, we report that nucleoside diphosphate kinase 2 (NME2) interacts with PTPσ. We screened proteins associated with PTPσ by mass spectrometry, and obtained NME2. Immunoprecipitation analysis revealed that NME2 associated with the PTPσ intracellular domain in HEK-293T cells. NME2 was expressed in the cytoplasm and nucleus of cortical neurons, and knockdown of NME2 in the cortical neurons completely rescued neurite outgrowth inhibition induced by CSPGs. These results demonstrate that NME2 associates with PTPσ to elicit neurite outgrowth inhibition in response to CSPGs.
Asunto(s)
Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Nucleósido Difosfato Quinasas NM23/metabolismo , Neuritas/fisiología , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/metabolismo , Animales , Núcleo Celular/enzimología , Corteza Cerebral/citología , Proteoglicanos Tipo Condroitín Sulfato/farmacología , Citoplasma/enzimología , Técnicas de Silenciamiento del Gen , Células HEK293 , Humanos , Espectrometría de Masas , Ratones , Nucleósido Difosfato Quinasas NM23/genética , Neuritas/efectos de los fármacos , Neuritas/metabolismo , Neuronas/enzimología , Neuronas/ultraestructura , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/genéticaRESUMEN
Obtaining a homogenous population of central nervous system neurons has been a significant challenge in neuroscience research; however, a recent study established a retinoic acid-treated embryoid bodies-based differentiation protocol that permits the effective generation of highly homogeneous glutamatergic cortical pyramidal neurons from embryonic stem cells. We were able to reproduce this protocol regarding the purity of glutamatergic neurons, but these neurons were not sufficiently healthy for long-term observation under the same conditions that were originally described. Here, we achieved a substantial improvement in cell survival by applying a simple technique: We changed the medium for glutamatergic neurons from the original complete medium to commercially available SBM (the Nerve-Cell Culture Medium manufactured by Sumitomo Bakelite Co. Ltd.) and finally succeeded in maintaining healthy neurons for at least 3 weeks without decreasing their purity. Because SBM contains glial conditioned medium, we postulated that brain-derived neurotrophic factor or basic fibroblast growth factor is the key components responsible for pro-survival effect of SBM on neurons, and examined their effects by adding them to CM. As a result, neither of them had pro-survival effect on pure glutamatergic neuronal population.
Asunto(s)
Técnicas de Cultivo de Célula , Células Madre Embrionarias/citología , Ácido Glutámico/metabolismo , Neurogénesis , Neuronas/citología , Animales , Apoptosis , Factor Neurotrófico Derivado del Encéfalo/farmacología , Caspasa 3/metabolismo , Supervivencia Celular , Células Madre Embrionarias/efectos de los fármacos , Factores de Crecimiento de Fibroblastos/farmacología , Ratones , Tubulina (Proteína)/metabolismoRESUMEN
Botulinum toxin-A (BTX) administration into muscle is an established treatment for conditions with excessive muscle contraction. However, botulinum therapy has short-term effectiveness, and high-dose injection of BTX could induce neutralizing antibodies against BTX. Therefore, prolonging its effects could be beneficial in a clinical situation. Insulin-like growth factor-1 receptor (IGF1R) and its ligands, insulin-like growth factor (IGF) -I and II, regulate the physiological and pathological processes of the nervous system. It has been suggested that IGF1R is involved in the process after BTX administration, but the specific regeneration mechanism remains unclear. Therefore, this study aimed to determine how inhibition of IGF1R signaling pathway affects BTX-induced muscle paralysis. The results showed that anti-IGF1R antibody administration inhibited the recovery from BTX-induced neurogenic paralysis, and the synaptic components at the neuromuscular junction (NMJ), mainly post-synaptic components, were significantly affected by the antibody. In addition, the wet weight or frequency distribution of the cross-sectional area of the muscle fibers was regulated by IGF1R, and sequential antibody administration following BTX treatment increased the number of Pax7+-satellite cells in the gastrocnemius (GC) muscle, independent of NMJ recovery. Moreover, BTX treatment upregulated mammalian target of rapamycin (mTOR)/S6 kinase signaling pathway, HDAC4, Myog, Fbxo32/MAFbx/Atrogin-1 pathway, and transcription of synaptic components, but not autophagy. Finally, IGF1R inhibition affected only mTOR/S6 kinase translational signaling in the GC muscle. In conclusion, the IGF1R signaling pathway is critical for NMJ regeneration via specific translational signals. IGF1R inhibition could be highly beneficial in clinical practice by decreasing the number of injections and total dose of BTX due to the prolonged duration of the effect.
Asunto(s)
Toxinas Botulínicas , Factor I del Crecimiento Similar a la Insulina , Unión Neuromuscular , Fibras Musculares Esqueléticas , Anticuerpos Neutralizantes/farmacologíaRESUMEN
Epidemiological evidence in humans has suggested that maternal infections and maternal autoimmune diseases are involved in the pathogenesis of autism spectrum disorder. Animal studies supporting human results have shown that maternal immune activation causes brain and behavioral alterations in offspring. Several underlying mechanisms, including interleukin-17A imbalance, have been identified. Apart from the pro-inflammatory effects of interleukin-17A, there is also evidence to support the idea that it activates neuronal function and defines cognitive behavior. In this review, we examined the signaling pathways in both immunological and neurological contexts that may contribute to the improvement of autism spectrum disorder symptoms associated with maternal blocking of interleukin-17A and adult exposure to interleukin-17A. We first describe the epidemiology of maternal immune activation then focus on molecular signaling of the interleukin-17 family regarding its physiological and pathological roles in the embryonic and adult brain. In the future, it may be possible to use interleukin-17 antibodies to prevent autism spectrum disorder.
RESUMEN
Repulsive guidance molecule (RGM) is a protein implicated in both axonal guidance and neural tube closure. We report RGMa as a potent inhibitor of axon regeneration in the adult central nervous system (CNS). RGMa inhibits mammalian CNS neurite outgrowth by a mechanism dependent on the activation of the RhoA-Rho kinase pathway. RGMa expression is observed in oligodendrocytes, myelinated fibers, and neurons of the adult rat spinal cord and is induced around the injury site after spinal cord injury. We developed an antibody to RGMa that efficiently blocks the effect of RGMa in vitro. Intrathecal administration of the antibody to rats with thoracic spinal cord hemisection results in significant axonal growth of the corticospinal tract and improves functional recovery. Thus, RGMa plays an important role in limiting axonal regeneration after CNS injury and the RGMa antibody offers a possible therapeutic agent in clinical conditions characterized by a failure of CNS regeneration.
Asunto(s)
Conos de Crecimiento/metabolismo , Inhibidores de Crecimiento/metabolismo , Glicoproteínas de Membrana/metabolismo , Regeneración Nerviosa/fisiología , Proteínas del Tejido Nervioso/metabolismo , Traumatismos de la Médula Espinal/metabolismo , Médula Espinal/metabolismo , Animales , Animales Recién Nacidos , Anticuerpos/inmunología , Anticuerpos/aislamiento & purificación , Anticuerpos/farmacología , Células CHO , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Células Cultivadas , Técnicas de Cocultivo , Cricetinae , Proteínas Ligadas a GPI , Conos de Crecimiento/ultraestructura , Inhibidores de Crecimiento/antagonistas & inhibidores , Inmunoglobulina G/farmacología , Inyecciones Espinales , Glicoproteínas de Membrana/antagonistas & inhibidores , Regeneración Nerviosa/efectos de los fármacos , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Tractos Piramidales/citología , Tractos Piramidales/efectos de los fármacos , Tractos Piramidales/metabolismo , Ratas , Recuperación de la Función/efectos de los fármacos , Recuperación de la Función/fisiología , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Médula Espinal/citología , Médula Espinal/efectos de los fármacos , Traumatismos de la Médula Espinal/fisiopatología , Regulación hacia Arriba/fisiología , Proteína de Unión al GTP rhoA/metabolismoRESUMEN
The 20-60 µm axon initial segment (AIS) is proximally located at the interface between the axon and cell body. AIS has characteristic molecular and structural properties regulated by the crucial protein, ankyrin-G. The AIS contains a high density of Na+ channels relative to the cell body, which allows low thresholds for the initiation of action potential (AP). Molecular and physiological studies have shown that the AIS is also a key domain for the control of neuronal excitability by homeostatic mechanisms. The AIS has high plasticity in normal developmental processes and pathological activities, such as injury, neurodegeneration, and neurodevelopmental disorders (NDDs). In the first half of this review, we provide an overview of the molecular, structural, and ion-channel characteristics of AIS, AIS regulation through axo-axonic synapses, and axo-glial interactions. In the second half, to understand the relationship between NDDs and AIS, we discuss the activity-dependent plasticity of AIS, the human mutation of AIS regulatory genes, and the pathophysiological role of an abnormal AIS in NDD model animals and patients. We propose that the AIS may provide a potentially valuable structural biomarker in response to abnormal network activity in vivo as well as a new treatment concept at the neural circuit level.
Asunto(s)
Segmento Inicial del Axón/patología , Trastornos del Neurodesarrollo/fisiopatología , Potenciales de Acción , Ancirinas/genética , Ancirinas/metabolismo , Segmento Inicial del Axón/metabolismo , Humanos , Canales Iónicos/metabolismo , Canales Iónicos/fisiología , Mutación , Trastornos del Neurodesarrollo/genética , Trastornos del Neurodesarrollo/metabolismo , Neuroglía/metabolismo , Plasticidad Neuronal , Espectrina/genética , Espectrina/metabolismo , Sinapsis/metabolismoRESUMEN
Neurotrophins (NTs) are one of the most characterized neurotrophic factor family members and consist of four members in mammals. Growing evidence suggests that there is a complex inter- and bi-directional relationship between central nervous system (CNS) disorders and cardiac dysfunction, so-called "brain-heart axis". Recent studies suggest that CNS disorders, including neurodegenerative diseases, stroke, and depression, affect cardiovascular function via various mechanisms, such as hypothalamic-pituitary-adrenal axis augmentation. Although this brain-heart axis has been well studied in humans and mice, the involvement of NT signaling in the axis has not been fully investigated. In the first half of this review, we emphasize the importance of NTs not only in the nervous system, but also in the cardiovascular system from the embryonic stage to the adult state. In the second half, we discuss the involvement of NTs in the pathogenesis of cardiovascular diseases, and then examine whether an alteration in NTs could serve as the mediator between neurological disorders and heart dysfunction. The further investigation we propose herein could contribute to finding direct evidence for the involvement of NTs in the axis and new treatment for cardiovascular diseases.
Asunto(s)
Cardiopatías , Animales , Factor Neurotrófico Derivado del Encéfalo , Sistema Hipotálamo-Hipofisario , Ratones , Sistema Hipófiso-Suprarrenal , Transducción de SeñalRESUMEN
The molecular mechanisms that regulate survival of embryonic neural precursors are still relatively ill-defined. Here, we have asked whether the p53 family member p63 plays any role during this developmental window, focusing on the embryonic cerebral cortex. We show that genetic knockdown of p63 either in culture or in the embryonic telencephalon causes apoptosis of cortical precursors and newly born cortical neurons, and that this can be rescued by expression of DeltaNp63, but not TAp63 isoforms. This cortical precursor apoptosis is the consequence of deregulated p53 activity, since both basal precursor apoptosis and that induced by loss of p63 are rescued by coincident genetic silencing of p53. Finally, we demonstrate that the third p53 family member, DeltaNp73, does not regulate survival of cortical precursor cells, but that it collaborates with DeltaNp63 to ensure the survival of newly born cortical neurons. Thus, the balance of DeltaNp63 versus p53 determines the life versus death of embryonic cortical precursors, a role that these p53 family members may well play in other populations of developing and/or adult neural precursors.
Asunto(s)
Diferenciación Celular/fisiología , Corteza Cerebral/citología , Células Madre Embrionarias/fisiología , Neuronas/fisiología , Fosfoproteínas/fisiología , Transactivadores/fisiología , Proteína p53 Supresora de Tumor/metabolismo , Análisis de Varianza , Animales , Caspasa 3/metabolismo , Recuento de Células/métodos , Diferenciación Celular/genética , Supervivencia Celular/genética , Células Cultivadas , Corteza Cerebral/embriología , Proteínas de Unión al ADN/deficiencia , Electroporación/métodos , Embrión de Mamíferos , Femenino , Regulación del Desarrollo de la Expresión Génica/genética , Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas Fluorescentes Verdes/genética , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación/genética , Proteínas Nucleares/deficiencia , Embarazo , ARN Interferente Pequeño/metabolismo , Tubulina (Proteína)/metabolismo , Proteína Tumoral p73 , Proteína p53 Supresora de Tumor/genética , Proteínas Supresoras de Tumor/deficienciaRESUMEN
Orexin (ORX) neurons in the hypothalamus send their axons to arousal-promoting areas. We have previously shown that glutamatergic neurons in the lateral parabrachial nucleus (LPB) innervate ORX neurons. In this study, we examined potential pathways from the LPB to ORX neurons projecting to arousal-promoting areas in the brainstem by a combination of tract-tracing techniques in male Wistar rats. We injected the anterograde tracer biotinylated dextranamine (BDA) into the LPB and the retrograde tracer cholera toxin B subunit (CTb) into the ventral tegmental area, dorsal raphe nucleus, pedunculopontine tegmental nucleus, laterodorsal tegmental area, or locus coeruleus (LC). We then analyzed the BDA-labeled fibers and ORX-immunoreactive neurons in the hypothalamus. We found that double-labeled ORX and CTb neurons were the most abundant after CTb was injected into the LC. We also observed prominently overlapping distribution of BDA-labeled fibers, arising from neurons located in the lateral-most part of the dorsomedial nucleus and adjacent dorsal perifornical area. In these areas, we confirmed by confocal microscopy that BDA-labeled synaptophysin-immunoreactive axon terminals were in contiguity with cell bodies and dendrites of CTb-labeled ORX-immunoreactive neurons. These results suggest that the LPB innervates arousal-promoting areas via ORX neurons and is likely to promote arousal responses to stimuli.
Asunto(s)
Nivel de Alerta , Tronco Encefálico/fisiología , Hipotálamo , Neuronas , Animales , Masculino , Vías Nerviosas , Orexinas , Ratas , Ratas WistarRESUMEN
Peroxisome biogenesis disorders (PBDs) manifest as neurological deficits in the central nervous system, including neuronal migration defects and abnormal cerebellum development. However, the mechanisms underlying pathogenesis remain enigmatic. Here, to investigate how peroxisome deficiency causes neurological defects of PBDs, we established a new PBD model mouse defective in peroxisome assembly factor Pex14p, termed Pex14 ΔC/ΔC mouse. Pex14 ΔC/ΔC mouse manifests a severe symptom such as disorganization of cortical laminar structure and dies shortly after birth, although peroxisomal biogenesis and metabolism are partially defective. The Pex14 ΔC/ΔC mouse also shows malformation of the cerebellum including the impaired dendritic development of Purkinje cells. Moreover, extracellular signal-regulated kinase and AKT signaling are attenuated in this mutant mouse by an elevated level of brain-derived neurotrophic factor (BDNF) together with the enhanced expression of TrkB-T1, a dominant-negative isoform of the BDNF receptor. Our results suggest that dysregulation of the BDNF-TrkB pathway, an essential signaling for cerebellar morphogenesis, gives rise to the pathogenesis of the cerebellum in PBDs.
RESUMEN
In order to establish a diagnostic criteria for diabetic polyneuropathy (DP) for daily practice, usefulness of the abbreviated diagnostic criteria proposed by Diabetic Neuropathy Study Group in Japan was examined in 131 diabetic patients in admission and outpatient clinic. The prerequisite condition includes: (1) diagnosed as diabetes and (2) other neuropathies than diabetic neuropathy can be excluded. The criteria should meet any of the following three items: (1) sensory symptoms considered to be due to DP, (2) bilaterally decreased or absent ankle reflex and (3) decreased vibratory sensation in bilateral medial malleoli. Using this criteria, sensitivity (68%) and specificity (74%) were obtained by evaluating nerve conduction study as gold standard, suggesting usefulness of the criteria for diagnosis of DP especially for daily practice. Staging of DP is now sought to establish the consensus for the specific therapy for its stage. Thirty-one diabetic patients in admission was evaluated to examine usefulness of the newly devised staging system of DP. Staging was almost consistent between the new staging system and Dyck's staging (gold standard) and nerve function deteriorated with increasing stage, suggesting that usefulness and rationale of this staging system is well substantiated.
Asunto(s)
Neuropatías Diabéticas/diagnóstico , Neuropatías Diabéticas/patología , Neuropatías Diabéticas/fisiopatología , Diagnóstico Diferencial , HumanosRESUMEN
The p53 family member p73 plays a critical role in brain development. p73 knockout mice exhibit a number of deficits in the nervous system, such as neuronal death, hydrocephalus, hippocampal dysgenesis, and pheromonal defects. Among these phenotypes, the mechanisms of hydrocephalus remain unknown. In this study, we generated a p73 knock-in (KI) mutant mouse and a conditional p73 knockout mouse. The homozygous KI mutants showed aqueductal stenosis. p73 was expressed in the ependymal cell layer and several brain areas. Unexpectedly, when p73 was disrupted during the postnatal period, animals showed aqueductal stenosis at a later stage but not hydrocephalus. An assessment of the integrity of cilia and basal body (BB) patch formation suggests that p73 is required to establish translational polarity but not to establish rotational polarity or the planar polarization of BB patches. Deletion of p73 in adult ependymal cells did not affect the maintenance of translational polarity. These results suggest that the loss of p73 during the embryonic period is critical for hydrocephalus development.
Asunto(s)
Encéfalo/metabolismo , Epéndimo/metabolismo , Hidrocefalia/metabolismo , Proteína Tumoral p73/metabolismo , Animales , Encéfalo/citología , Encéfalo/embriología , Polaridad Celular/genética , Cilios/genética , Cilios/metabolismo , Epéndimo/citología , Epéndimo/embriología , Regulación del Desarrollo de la Expresión Génica , Hidrocefalia/genética , Hidrocefalia/patología , Ratones Noqueados , Ratones Transgénicos , Proteína Tumoral p73/genéticaRESUMEN
Cortical neurogenesis is a fundamental process of brain development that is spatiotemporally regulated by both intrinsic and extrinsic cues. Although recent evidence has highlighted the significance of transcription factors in cortical neurogenesis, little is known regarding the role of RNA-binding proteins (RBPs) in the post-transcriptional regulation of cortical neurogenesis. Here, we report that meiosis arrest female 1 (MARF1) is an RBP that is expressed during neuronal differentiation. Cortical neurons expressed the somatic form of MARF1 (sMARF1) but not the oocyte form (oMARF1). sMARF1 was enriched in embryonic brains, and its expression level decreased as brain development progressed. Overexpression of sMARF1 in E12.5 neuronal progenitor cells promoted neuronal differentiation, whereas sMARF1 knockdown decreased neuronal progenitor differentiation in vitro. We also examined the function of sMARF1 in vivo using an in utero electroporation technique. Overexpression of sMARF1 increased neuronal differentiation, whereas knockdown of sMARF1 inhibited differentiation in vivo. Moreover, using an RNase domain deletion mutant of sMARF1, we showed that the RNase domain is required for the effects of sMARF1 on cortical neurogenesis in vitro. Our results further elucidate the mechanisms of post-transcriptional regulation of cortical neurogenesis by RBPs.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Corteza Cerebral/embriología , Neurogénesis , Proteínas de Unión al ARN/metabolismo , Ribonucleasas/metabolismo , Animales , Diferenciación Celular , Células Cultivadas , Perfilación de la Expresión Génica , Ratones Endogámicos ICR , Células Madre Pluripotentes/fisiologíaRESUMEN
Repulsive guidance molecule (RGM) is a protein implicated in both axonal guidance and neural tube closure. We examined the expression of RGMa in the spinal cord after the sciatic nerve crush by immunohistochemistry. Although there was no RGMa immunoreactivity under naïve conditions in the dorsal horn, a weak signal for RGMa was found at 24 h after the nerve crush, and this signal was progressively increased in the NeuN-positive neurons in the ipsilateral dorsal horn from superficial to deep layers at 10 days after surgery. In the neurons of the ipsilateral ventral horn, RGMa was also induced at 10 days after surgery, whereas no RGMa signal could be observed in naïve conditions or at 24 h after surgery. Thus, RGMa expression is upregulated both in the ipsilateral dorsal and ventral horns in response to the sciatic nerve injury. We next examined the effects of complete Freund's adjuvant (CFA)-induced inflammation on RGMa expression in the spinal cord. However, no RGMa expression was observed at 24 h and 10 days after the CFA injection in the dorsal horn, suggesting that RGMa is not involved in inflammation-induced gyperalgesia. Our present study demonstrates that induction of RGMa is associated with the peripheral nerve injury.
Asunto(s)
Glicoproteínas de Membrana/metabolismo , Degeneración Nerviosa/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neuronas/metabolismo , Nervio Ciático/lesiones , Médula Espinal/metabolismo , Animales , Western Blotting , Proteínas Ligadas a GPI , Inmunohistoquímica , Masculino , Compresión Nerviosa , Degeneración Nerviosa/patología , Neuronas/patología , Ratas , Ratas Sprague-Dawley , Nervio Ciático/metabolismo , Nervio Ciático/patologíaRESUMEN
Several myelin-derived proteins have been identified as components of the CNS myelin that prevents axonal regeneration in the adult vertebrate CNS. Activation of RhoA has been shown to be an essential part of the signaling mechanism of these proteins. Here we report an additional signal, which determines whether these proteins promote or inhibit axon outgrowth. Myelin-associated glycoprotein (MAG) and Nogo trigger the intracellular elevation of Ca2+ as well as the activation of PKC, presumably mediated by G(i)/G. Neurite outgrowth inhibition and growth cone collapse by MAG or Nogo can be converted to neurite extension and growth cone spreading by inhibiting conventional PKC, but not by inhibiting inositol 1,4,5-triphosphate (IP3). Conversely, neurite growth of immature neurons promoted by MAG is abolished by inhibiting IP3. Activation of RhoA is independent of PKC. Thus, a balance between PKC and IP3 is important for bidirectional regulation of axon regeneration by the myelin-derived proteins.
Asunto(s)
Axones/efectos de los fármacos , Proteínas de Unión al GTP Heterotriméricas/fisiología , Proteínas de la Mielina/farmacología , Glicoproteína Asociada a Mielina/farmacología , Regeneración Nerviosa/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Animales , Embrión de Pollo , Ganglios Espinales/citología , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/embriología , Conos de Crecimiento/fisiología , Inositol 1,4,5-Trifosfato/fisiología , Proteínas Nogo , Proteína Quinasa C/fisiología , Ratas , Transducción de Señal/fisiología , Fosfolipasas de Tipo C/fisiología , Proteína de Unión al GTP rhoA/fisiologíaRESUMEN
Several myelin-derived proteins have been identified as components of central nervous system (CNS) myelin, which prevents axonal regeneration in the adult vertebrate CNS. The discovery of the receptor for these proteins was a major step toward understanding the failure of axon regeneration. The receptor complex consists of at least three elements: the p75 receptor (p75NTR), the Nogo receptor and LINGO-1. Downstream from the receptor complex, RhoA activation has been shown to be a key element of the signaling mechanism of these proteins. Rho activation arrests axon growth, and blocking Rho activation promotes axon regeneration in vivo. Recent studies have identified conventional protein kinase C as an additional necessary component for axon growth inhibition. Possible crosstalk downstream of these signals should be explored to clarify all the inhibitory signals and may provide an efficient molecular target against injuries to the CNS.
Asunto(s)
Axones/metabolismo , Proteínas de la Mielina/metabolismo , Regeneración Nerviosa , Transducción de Señal , Animales , Humanos , Proteínas Nogo , Proteína Quinasa C/metabolismo , Proteínas de Unión al GTP rho/metabolismoRESUMEN
The pan-neurotrophin receptor p75NTR belongs to a large family of receptors, which includes tumor necrosis factor receptors, Fas and approximately 25 other members. The p75NTR is the first receptor to be cloned molecularly. Recent years have seen the emergence of a consensus regarding the signaling pathways activated by p75NTR and its potential biological function, although receptor characterization had not been targeted for some years. We now know that p75NTR has surprisingly diverse effects, ranging from cell death to regulation of axon elongation. This diversity can be explained by the complex formation of p75NTR with other receptors and multiple signaling molecules that interact with the intracellular domain of p75NTR.