RESUMEN
Contusive spinal cord injury leads to a variety of disabilities owing to limited neuronal regeneration and functional plasticity. It is well established that an upregulation of glial-derived chondroitin sulphate proteoglycans (CSPGs) within the glial scar and perineuronal net creates a barrier to axonal regrowth and sprouting. Protein tyrosine phosphatase σ (PTPσ), along with its sister phosphatase leukocyte common antigen-related (LAR) and the nogo receptors 1 and 3 (NgR), have recently been identified as receptors for the inhibitory glycosylated side chains of CSPGs. Here we find in rats that PTPσ has a critical role in converting growth cones into a dystrophic state by tightly stabilizing them within CSPG-rich substrates. We generated a membrane-permeable peptide mimetic of the PTPσ wedge domain that binds to PTPσ and relieves CSPG-mediated inhibition. Systemic delivery of this peptide over weeks restored substantial serotonergic innervation to the spinal cord below the level of injury and facilitated functional recovery of both locomotor and urinary systems. Our results add a new layer of understanding to the critical role of PTPσ in mediating the growth-inhibited state of neurons due to CSPGs within the injured adult spinal cord.
Asunto(s)
Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Regeneración Nerviosa , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/metabolismo , Traumatismos de la Médula Espinal/metabolismo , Secuencia de Aminoácidos , Animales , Matriz Extracelular/química , Matriz Extracelular/efectos de los fármacos , Matriz Extracelular/metabolismo , Femenino , Conos de Crecimiento/efectos de los fármacos , Conos de Crecimiento/fisiología , Humanos , Ratones , Datos de Secuencia Molecular , Regeneración Nerviosa/efectos de los fármacos , Unión Proteica/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/antagonistas & inhibidores , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/química , Traumatismos de la Médula Espinal/patologíaRESUMEN
Severed axon tips reform growth cones following spinal cord injury that fail to regenerate, in part, because they become embedded within an inhibitory extracellular matrix. Chondroitin sulfate proteoglycans (CSPGs) are the major axon inhibitory matrix component that is increased within the lesion scar and in perineuronal nets around deafferented neurons. We have recently developed a novel peptide modulator (intracellular sigma peptide) of the cognate receptor of CSPGs, protein tyrosine phosphatase σ (RPTPσ), which has been shown to markedly improve sensorimotor function, micturition, and coordinated locomotor behavior in spinal cord contused rats. However, the mechanism(s) underlying how modulation of RPTPσ mediates axon outgrowth through inhibitory CSPGs remain unclear. Here, we describe how intracellular sigma peptide modulation of RPTPσ induces enhanced protease Cathepsin B activity. Using DRG neurons from female Sprague Dawley rats cultured on an aggrecan/laminin spot assay and a combination of biochemical techniques, we provide evidence suggesting that modulation of RPTPσ regulates secretion of proteases that, in turn, relieves CSPG inhibition through its digestion to allow axon migration though proteoglycan barriers. Understanding the mechanisms underlying RPTPσ modulation elucidates how axon regeneration is impaired by proteoglycans but can then be facilitated following injury.SIGNIFICANCE STATEMENT Following spinal cord injury, chondroitin sulfate proteoglycans (CSPGs) upregulate and potently inhibit axon regeneration and functional recovery. Protein tyrosine phosphatase σ (RPTPσ) has been identified as a critical cognate receptor of CSPGs. We have previously characterized a synthetic peptide (intracellular sigma peptide) that targets the regulatory intracellular domain of the receptor to allow axons to regenerate despite the presence of CSPGs. Here, we have found that one important mechanism by which peptide modulation of the receptor enhances axon outgrowth is through secretion of a protease, Cathepsin B, which enables digestion of CSPGs. This work links protease secretion to the CSPG receptor RPTPσ for the first time with implications for understanding the molecular mechanisms underlying neural regeneration and plasticity.
Asunto(s)
Catepsina B/metabolismo , Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Regeneración Nerviosa/fisiología , Proyección Neuronal/fisiología , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/metabolismo , Animales , Células Cultivadas , Femenino , Ratas , Ratas Sprague-DawleyRESUMEN
The inhibition of emopamil binding protein (EBP), a sterol isomerase within the cholesterol biosynthesis pathway, promotes oligodendrocyte formation, which has been proposed as a potential therapeutic approach for treating multiple sclerosis. Herein, we describe the discovery and optimization of brain-penetrant, orally bioavailable inhibitors of EBP. A structure-based drug design approach from literature compound 1 led to the discovery of a hydantoin-based scaffold, which provided balanced physicochemical properties and potency and an improved in vitro safety profile. The long half-lives of early hydantoin-based EBP inhibitors in rodents prompted an unconventional optimization strategy, focused on increasing metabolic turnover while maintaining potency and a brain-penetrant profile. The resulting EBP inhibitor 11 demonstrated strong in vivo target engagement in the brain, as illustrated by the accumulation of EBP substrate zymostenol after repeated dosing. Furthermore, compound 11 enhanced the formation of oligodendrocytes in human cortical organoids, providing additional support for our therapeutic hypothesis.
Asunto(s)
Encéfalo , Hidantoínas , Humanos , Oligodendroglía/metabolismo , Diseño de Fármacos , Hidantoínas/metabolismoRESUMEN
We investigated intracerebral hemorrhage (ICH)-induced lateral migration of neuroblasts and the mechanism underlying this migration. ICH model was induced by collagenase injection into the striatum of adult wild-type and osteopontin (OPN) knockout mice. In the wild-type mice, the lateral migration of neuroblasts from the ipsilateral subventricular zone (SVZ) towards the hematoma started at day 3 and continued up to day 28 after ICH. In addition to migrating towards the hematoma, neuroblasts also migrated to the area of ipsilateral striatum remote to the hematoma. The migrating neuroblasts were closely associated with activated astrocytes and blood vessels in the injured striatum. Following ICH, the expression of OPN was up-regulated in the ipsilateral striatum from day 1 to day 28. In vitro, OPN treatment did not affect the proliferation of neural progenitors, but enhanced the trans-well and radial migration of neural progenitors. In vivo, OPN deficiency did not affect the proliferation of neural progenitors in the SVZ. However, following ICH a significant decrease in lateral neuroblast migration was observed in the OPN knockout mice compared with the wild-type mice. These results suggest that increased OPN expression in the injured striatum plays a significant role in the lateral migration of neuroblasts following ICH.
Asunto(s)
Células Madre Adultas/fisiología , Movimiento Celular/fisiología , Hemorragia Cerebral/patología , Hemorragia Cerebral/fisiopatología , Ventrículos Cerebrales/patología , Cuerpo Estriado/fisiopatología , Osteopontina/metabolismo , Células Madre Adultas/efectos de los fármacos , Animales , Astrocitos/efectos de los fármacos , Astrocitos/fisiología , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Hemorragia Cerebral/inducido químicamente , Colagenasas , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/patología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Proteínas de Dominio Doblecortina , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Proteína Ácida Fibrilar de la Glía/metabolismo , Proteínas de Filamentos Intermediarios/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Nestina , Neuropéptidos/metabolismo , Osteopontina/deficiencia , Osteopontina/farmacología , Factores de TiempoRESUMEN
Acute injuries to CNS such as stroke induce neural progenitor proliferation in adult brain which might be an endogenous attempt to self-repair. This process is known to be altered by several exogenous and endogenous modulators including growth factors that could help to reinforce the post-stroke neurogenesis. Increasing the neurogenesis may be a future therapeutic option to decrease the cognitive and behavioral deficits following stroke. In addition, transplantation of various types of stem cells into the injured brain is currently thought to be an exciting option to replace the neurons lost in the post-ischemic brain. These include immortalized stem cell lines, neural progenitors prepared from embryonic and adult animals and mesenchymal stem cells. Using exogenous stem cells in addition to modulating endogenous neurogenesis, we may be able to repair the injured brain after a devastating stroke. This article reviewed the current literature of these two issues.
Asunto(s)
Lesiones Encefálicas/patología , Lesiones Encefálicas/cirugía , Neurogénesis , Trasplante de Células Madre , Accidente Cerebrovascular/patología , Accidente Cerebrovascular/cirugía , Animales , Lesiones Encefálicas/etiología , Lesiones Encefálicas/psicología , Trastornos del Conocimiento/etiología , Humanos , Trastornos Mentales/etiología , Recuperación de la Función , Trasplante de Células Madre/métodos , Trasplante de Células Madre/tendencias , Accidente Cerebrovascular/complicaciones , Resultado del TratamientoRESUMEN
Following spinal cord injury (SCI), inflammation amplifies damage beyond the initial insult, providing an opportunity for targeted treatments. An ideal protective therapy would reduce both edema within the lesion area and the activation/infiltration of detrimental immune cells. Previous investigations demonstrated the efficacy of intravenous injection of multipotent adult progenitor cells (MAPC®) to modulate immune response following SCI, leading to significant improvements in tissue sparing, locomotor and urological functions. Separate studies have demonstrated that tissue inhibitor of matrix metalloproteinase-3 (TIMP3) reduces blood-brain barrier permeability following traumatic brain injury in a mouse model, leading to improved functional recovery. This study examined whether TIMP3, delivered alone or in concert with MAPC cells, improves functional recovery from a contusion SCI in a rat model. The results suggest that intravenous delivery of MAPC cell therapy 1 day following acute SCI significantly improves tissue sparing and impacts functional recovery. TIMP3 treatment provided no significant benefit, and further, when co-administered with MAPC cells, it abrogated the therapeutic effects of MAPC cell therapy. Importantly, this study demonstrated for the first time that acute treatment of SCI with MAPC cells can significantly reduce the incidence of urinary tract infection (UTI) and the use of antibiotics for UTI treatment.
Asunto(s)
Células Madre Multipotentes/trasplante , Recuperación de la Función , Traumatismos de la Médula Espinal , Inhibidor Tisular de Metaloproteinasa-3/farmacología , Infecciones Urinarias , Células Madre Adultas/trasplante , Animales , Femenino , Humanos , Distribución Aleatoria , Ratas , Ratas Sprague-Dawley , Recuperación de la Función/efectos de los fármacos , Recuperación de la Función/fisiología , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/patología , Trasplante de Células Madre/métodos , Infecciones Urinarias/epidemiología , Infecciones Urinarias/etiologíaRESUMEN
Multiple Sclerosis (MS) is characterized by focal CNS inflammation leading to the death of oligodendrocytes (OLs) with subsequent demyelination, neuronal degeneration, and severe functional deficits. Inhibitory chondroitin sulfate proteoglycans (CSPGs) are increased in the extracellular matrix in the vicinity of MS lesions and are thought to play a critical role in myelin regeneration failure. We here show that CSPGs curtail remyelination through binding with their cognate receptor, protein tyrosine phosphatase σ (PTPσ) on oligodendrocyte progenitor cells (OPCs). We report that inhibition of CSPG/PTPσ signaling by systemically deliverable Intracellular Sigma Peptide (ISP), promotes OPC migration, maturation, remyelination, and functional recovery in animal models of MS. Furthermore, we report a downstream molecular target of PTPσ modulation in OPCs involving upregulation of the protease MMP-2 that allows OPCs to enzymatically digest their way through CSPGs. In total, we demonstrate a critical role of PTPσ/CSPG interactions in OPC remyelination in MS.
Asunto(s)
Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Encefalomielitis Autoinmune Experimental/metabolismo , Metaloproteinasa 2 de la Matriz/metabolismo , Esclerosis Múltiple/metabolismo , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/metabolismo , Secuencia de Aminoácidos , Animales , Animales Recién Nacidos , Movimiento Celular/efectos de los fármacos , Células Cultivadas , Encefalomielitis Autoinmune Experimental/prevención & control , Humanos , Ratones Endogámicos C57BL , Esclerosis Múltiple/prevención & control , Oligodendroglía/efectos de los fármacos , Oligodendroglía/metabolismo , Péptidos/farmacología , Unión Proteica/efectos de los fármacos , Células Madre/efectos de los fármacos , Células Madre/metabolismoRESUMEN
Transient focal ischemia is known to induce proliferation of neural progenitors in adult rodent brain. We presently report that doublecortin positive neuroblasts formed in the subventricular zone (SVZ) and the posterior peri-ventricle region migrate towards the cortical and striatal penumbra after transient middle cerebral artery occlusion (MCAO) in adult rodents. Cultured neural progenitor cells grafted into the non-infarcted area of the ipsilateral cortex migrated preferentially towards the infarct. As chemokines are known to induce cell migration, we investigated if monocyte chemoattractant protein-1 (MCP-1) has a role in post-ischemic neuroblast migration. Transient MCAO induced an increased expression of MCP-1 mRNA in the ipsilateral cortex and striatum. Immunostaining showed that the expression of MCP-1 was localized in the activated microglia and astrocytes present in the ischemic areas between days 1 and 3 of reperfusion. Furthermore, infusion of MCP-1 into the normal striatum induced neuroblast migration to the infusion site. The migrating neuroblasts expressed the MCP-1 receptor CCR2. In knockout mice that lacked either MCP-1 or its receptor CCR2, there was a significant decrease in the number of migrating neuroblasts from the ipsilateral SVZ to the ischemic striatum. These results show that MCP-1 is one of the factors that attract the migration of newly formed neuroblasts from neurogenic regions to the damaged regions of brain after focal ischemia.
Asunto(s)
Isquemia Encefálica/patología , Movimiento Celular , Quimiocina CCL2/fisiología , Neuronas/fisiología , Animales , Proliferación Celular , Quimiocina CCL2/genética , Proteína Doblecortina , Infarto de la Arteria Cerebral Media , Ratones , Ratones Noqueados , Neuronas/citología , ARN Mensajero/análisis , Ratas , Receptores CCR2 , Receptores de Quimiocina/análisis , Regulación hacia ArribaRESUMEN
Following root avulsion, spinal nerves are physically disconnected from the spinal cord. Severe motoneuron death and inefficient axon regeneration often result in devastating motor dysfunction. Newly formed axons need to extend through inhibitory scar tissue at the CNS-PNS transitional zone before entering into a pro-regenerative peripheral nerve trajectory. CSPGs are dominant suppressors in scar tissue and exert inhibition via neuronal receptors including PTPσ. Previously, a small peptide memetic of the PTPσ wedge region named ISP (Intracellular Sigma Peptide) was generated, and its capabilities to target PTPσ and relieve CSPG inhibition were validated. Here, we demonstrate that after ventral root avulsion and immediate re-implantation, modulation of PTPσ by systemic delivery of ISP remarkably enhanced regeneration. ISP treatment reduced motoneuron death, increased the number of axons regenerating across scar tissue, rebuilt healthy neuromuscular junctions and enhanced motor functional recovery. Our study shows that modulation of PTPσ is a potential therapeutic strategy for root avulsion.
Asunto(s)
Péptidos y Proteínas de Señalización Intracelular/administración & dosificación , Radiculopatía/fisiopatología , Radiculopatía/terapia , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/metabolismo , Recuperación de la Función/fisiología , Regeneración de la Medula Espinal/fisiología , Animales , Fármacos del Sistema Nervioso Central/administración & dosificación , Relación Dosis-Respuesta a Droga , Femenino , Proteoglicanos/metabolismo , Ratas , Ratas Sprague-Dawley , Recuperación de la Función/efectos de los fármacos , Regeneración de la Medula Espinal/efectos de los fármacos , Raíces Nerviosas Espinales/efectos de los fármacos , Raíces Nerviosas Espinales/fisiopatología , Resultado del TratamientoRESUMEN
Following spinal cord injury (SCI), immune-mediated secondary processes exacerbate the extent of permanent neurological deficits. We investigated the capacity of adult bone marrow-derived stem cells, which exhibit immunomodulatory properties, to alter inflammation and promote recovery following SCI. In vitro, we show that human multipotent adult progenitor cells (MAPCs) have the ability to modulate macrophage activation, and prior exposure to MAPC secreted factors can reduce macrophage-mediated axonal dieback of dystrophic axons. Using a contusion model of SCI, we found that intravenous delivery of MAPCs one day, but not immediately, after SCI significantly improves urinary and locomotor recovery, which was associated with marked spinal cord tissue sparing. Intravenous MAPCs altered the immune response in the spinal cord and periphery, however biodistribution studies revealed that no MAPCs were found in the cord and instead preferentially homed to the spleen. Our results demonstrate that MAPCs exert their primary effects in the periphery and provide strong support for the use of these cells in acute human contusive SCI.
Asunto(s)
Células Madre Adultas/citología , Inflamación/complicaciones , Inflamación/terapia , Células Madre Multipotentes/citología , Recuperación de la Función , Traumatismos de la Médula Espinal/fisiopatología , Traumatismos de la Médula Espinal/terapia , Trasplante de Células Madre , Adulto , Animales , Arginasa/metabolismo , Axones/patología , Femenino , Humanos , Inyecciones Intravenosas , Macrófagos/patología , Actividad Motora , Óxido Nítrico Sintasa de Tipo II/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Fenotipo , Ratas Sprague-Dawley , Distribución Tisular , MicciónRESUMEN
Astrocytes react to CNS injury by building a dense wall of filamentous processes around the lesion. Stromal cells quickly take up residence in the lesion core and synthesize connective tissue elements that contribute to fibrosis. Oligodendrocyte precursor cells proliferate within the lesion and entrap dystrophic axon tips. Here we review evidence that this aggregate scar acts as the major barrier to regeneration of axons after injury. We also consider several exciting new interventions that allow axons to regenerate beyond the glial scar, and discuss the implications of this work for the future of regeneration biology.
Asunto(s)
Cicatriz/patología , Cicatriz/fisiopatología , Regeneración Nerviosa/fisiología , Neuroglía/fisiología , Animales , HumanosRESUMEN
Neuroinflammation is the foremost defense reaction of the nervous system to most if not all insults. Injuries to the central and peripheral nervous system (CNS and PNS) are followed by immediate activation of innate immune cells and infiltration of peripheral immune cells, amid waves of upregulation of numerous inflammatory mediators. Prolonged inflammation can lead to secondary tissue damage and prohibit regeneration of the injured nervous system. The regulation of inflammation and neuroregeneration are orchestrated through a complex network of signal transduction. Interestingly, many molecules play pleiotropic roles in both processes. Growing evidence implicates a handful of axon regeneration regulators in the processes of neuroinflammation, among which are the myelin and glial scar associated axon growth inhibitors and their axonal receptors. In this article, we will review the roles of these canonical axon regeneration regulators in neuroinflammation.
Asunto(s)
Axones/fisiología , Pleiotropía Genética/fisiología , Mediadores de Inflamación/metabolismo , Regeneración Nerviosa/fisiología , Animales , Axones/patología , Humanos , Inflamación/inmunología , Inflamación/metabolismo , Inflamación/patología , Neuronas/patología , Neuronas/fisiologíaRESUMEN
Addition of a small peptide called ISG15 is known as ISGylation, which is an ubiquitin (ub)-like posttranslational modification. We currently show that focal ischemia induced by transient middle cerebral artery occlusion (MCAO) in adult mice significantly induces cortical protein ISGylation between 6 and 24 hours reperfusion. With two-dimensional western blotting, 45 proteins were observed to be significantly increased in ISGylation (by 1.8- to 9.7-fold) after focal ischemia compared with sham control. Immunochemistry showed that ISGylated proteins are localized in neurons within the ipsilateral striatum and in astroglia within the peri-infarct cortex of ischemic mice. When subjected to transient MCAO, ISG15(-/-) mice showed increased mortality, exacerbated infarction, and worsened neurologic recovery than did wild-type controls. In addition, mice lacking UBE1L (ub-activating enzyme E1-like protein, the first enzyme of the ISGylation cycle) also showed bigger infarcts when subjected to transient MCAO. Regional cerebral blood flow or other physiologic parameters were not significantly different in both knockouts compared with wild-type controls. These studies indicate that increased protein ISGylation might be an endogenous neuroprotective adaptation to minimize poststroke brain damage.
Asunto(s)
Isquemia Encefálica/patología , Citocinas/metabolismo , Animales , Astrocitos/patología , Western Blotting , Citocinas/genética , Electroforesis en Gel Bidimensional , Inmunohistoquímica , Infarto de la Arteria Cerebral Media/patología , Ataque Isquémico Transitorio/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Neuronas/patología , Desempeño Psicomotor/fisiología , Proteína SUMO-1/metabolismo , Enzimas Activadoras de Ubiquitina/genética , Ubiquitinación , Ubiquitinas/genética , Ubiquitinas/metabolismoRESUMEN
Galectin-3 (Gal-3) is a member of a class of carbohydrate-binding proteins and plays a role in a number of cellular functions such as cell proliferation, angiogenesis and differentiation. We observed an up-regulated expression of Gal-3 in the ischemic brain following transient middle cerebral artery occlusion in rats. Compared to the brain of sham-operated rats, the expression of Gal-3 was increased in the ischemic striatum at day 1 of reperfusion. The number of Gal-3+ cells in the ischemic brain was further increased at day 2 and day 3, and peaked at day 7 of reperfusion. The up-regulated expression of Gal-3 persisted from day 14 to 2 months after reperfusion. Double staining showed co-localization of Gal-3 with OX-42+ cells, glial fibrillary acidic protein (GFAP)+ and ED1+ cells, suggesting that activated microglia/infiltrating macrophages and activated astrocytes are the primary source of Gal-3 in the ischemic brain. In the in vitro setting, Gal-3 treatment dose-dependently stimulated the proliferation of endothelial cells and neural progenitors. Blockade of Gal-3 activity by infusing a neutralizing antibody against Gal-3 into the ischemic striatum decreased ischemia-induced angiogenesis and the proliferation of neural progenitors. These results suggest that Gal-3 expressed by activated microglia/infiltrating macrophages and astrocytes in the ischemic brain may play a role in post-ischemic tissue remodeling by enhancing angiogenesis and neurogenesis.
Asunto(s)
Cuerpo Estriado/metabolismo , Galectina 3/metabolismo , Ataque Isquémico Transitorio/metabolismo , Análisis de Varianza , Animales , Astrocitos/metabolismo , Isquemia Encefálica/metabolismo , Recuento de Células , Proliferación Celular , Células Cultivadas , Cuerpo Estriado/irrigación sanguínea , Relación Dosis-Respuesta a Droga , Células Endoteliales/metabolismo , Ensayo de Inmunoadsorción Enzimática , Inmunohistoquímica , Infarto de la Arteria Cerebral Media/metabolismo , Activación de Macrófagos , Macrófagos/metabolismo , Masculino , Microglía/metabolismo , Neuronas/metabolismo , Ratas , Ratas Endogámicas SHR , Reperfusión , Regulación hacia ArribaRESUMEN
We and others have shown that focal cerebral ischemia induces lateral migration of neuroblasts from the ipsilateral subventricular zone (SVZ) to the ischemic striatum. The signaling pathways underlying this phenomenon are not fully understood. The present study examined the role of osteopontin (OPN) in post-ischemic lateral migration of neuroblasts. Focal ischemia was induced by transient middle cerebral artery occlusion in adult spontaneous hypertensive rats. The expression of OPN in the ischemic brain was evaluated by immunohistochemistry, which showed that an up-regulation of OPN expression in the ipsilateral striatum at day 3, 7, 14 and 1 month of reperfusion with a peak at day 7. Double staining showed co-localization of OPN with ED1(+) macrophages/microglia in the ischemic regions. Inhibition of OPN activity by infusing a neutralizing antibody against OPN into the ischemic striatum significantly decreased the area covered with doublecortin(+) neuroblasts in the ipsilateral striatum. In vitro, OPN treatment did not affect the proliferation of neural progenitors, but induced an increased trans-well and radial migration of neural progenitors. The cultured neural progenitors expressed the OPN receptors CD44 and integrin beta(1). Blockade of the CD44 receptor had no effects on OPN mediated trans-well and radial migration of neural progenitors. However, blockade of integrin beta(1) receptor abolished the migration of neural progenitors in the absence or the presence of OPN. These results suggest that up-regulated expression of OPN produced by macrophages/microglia in the ischemic brain is an attractant and inducer for the lateral migration of neuroblasts from the SVZ to the injured region.
Asunto(s)
Isquemia Encefálica/metabolismo , Movimiento Celular/fisiología , Regeneración Nerviosa/fisiología , Neurogénesis/fisiología , Osteopontina/metabolismo , Células Madre/metabolismo , Animales , Anticuerpos Neutralizantes/farmacología , Isquemia Encefálica/fisiopatología , Diferenciación Celular/fisiología , Proliferación Celular , Células Cultivadas , Modelos Animales de Enfermedad , Proteínas de Dominio Doblecortina , Proteína Doblecortina , Receptores de Hialuranos/metabolismo , Infarto de la Arteria Cerebral Media/metabolismo , Infarto de la Arteria Cerebral Media/fisiopatología , Cadenas beta de Integrinas/metabolismo , Masculino , Proteínas Asociadas a Microtúbulos/metabolismo , Degeneración Nerviosa/metabolismo , Degeneración Nerviosa/fisiopatología , Neuronas/citología , Neuronas/metabolismo , Neuropéptidos/metabolismo , Ratas , Ratas Endogámicas SHR , Células Madre/citología , Telencéfalo/citología , Telencéfalo/metabolismo , Telencéfalo/fisiopatologíaRESUMEN
Type-2 diabetes is an adult onset condition that affects millions of people worldwide. The ensuing hyperglycemia renders multiple organs to various complications and increases the risk of learning and memory impairment. The Goto-Kakizaki (GK) rat developed from normoglycemic Wistar-Kyoto (WKY) rat is a model for type-2 diabetes, with insulin resistance developing around 12 weeks of age. We presently analyzed the neural progenitor proliferation and survival of the newly generated cells in the dentate gyrus (DG) and the subventricular zone (SVZ) of 6 and 18 week-old GK and WKY rats. At 6 weeks of age, both GK and WKY cohorts showed similar blood glucose levels (112+/-14 mg/dL) and similar rates of neural progenitor proliferation. At 18 weeks of age, the GK rats showed significantly increased blood glucose levels (by 92+/-12%; p<0.05) and higher number of proliferating neural progenitor cells compared to WKY rats (by 183+/-16% in SVZ and by 36+/-5% in DG; p<0.05 in both cases). In both the neurogenic areas, 52+/-9% of the newly formed cells survived to 3 weeks in the 18 weeks old WKY rats, but in the GK rats only 16+/-7% of the new cells survived to 3 weeks. When cultured from the DG of the 18 week old rats in the presence of FGF2 and IGF1, the GK cohort yielded significantly lower number of neurospheres than the WKY cohort (by 69+/-7%; p<0.05). These results indicate that hyperglycemic environment induces proliferation of adult neural progenitors, but detrimental to their survival. Impaired neurogenesis might be a promoter of the decreased brain function in type-2 diabetes.
Asunto(s)
Diabetes Mellitus Tipo 2/fisiopatología , Neurogénesis/fisiología , Análisis de Varianza , Animales , Glucemia/análisis , Bromodesoxiuridina , Supervivencia Celular , Células Cultivadas , Giro Dentado/fisiopatología , Modelos Animales de Enfermedad , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Hiperglucemia/fisiopatología , Inmunohistoquímica , Factor I del Crecimiento Similar a la Insulina/metabolismo , Ventrículos Laterales/fisiopatología , Ratas , Ratas Endogámicas WKY , Células Madre/fisiologíaRESUMEN
Peroxisome proliferator-activated receptor (PPAR)-gamma is a ligand-activated transcription factor of nuclear hormone receptor superfamily. Thiazolidinedione rosiglitazone is a potent agonist of PPARgamma which was shown to induce neuroprotection in animal models of focal ischemia and spinal cord injury. We currently evaluated the therapeutic potential of rosiglitazone (6 mg/kg at 5 min, 6 h and 24 h; i.p.) following controlled cortical impact (CCI)-induced traumatic brain injury (TBI) in adult mice. CCI injury increased the cortical PPARgamma mRNA levels which were further elevated by rosiglitazone treatment. In addition, rosiglitazone treatment significantly decreased the cortical lesion volume measured at 7 days compared to vehicle treatment (by 56+/-7%; p<0.05; n=6/group). Following TBI, the spared cortex of the rosiglitazone group showed significantly less numbers of GSI-B4(+) activated microglia/macrophages and ICAM1(+) capillaries, and curtailed induction of pro-inflammatory genes IL6, MCP1 and ICAM1 compared to vehicle group. Rosiglitazone-treated mice also showed significantly less number of TUNEL(+) apoptotic neurons and curtailed induction of caspase-3 and Bax, compared to vehicle control. In addition, rosiglitazone significantly enhanced the post-TBI expression of the neuroprotective chaperones HSP27, HSP70 and HSP32/HO1, and the anti-oxidant enzymes catalase, Cu/Zn-SOD and Mn-SOD, compared to vehicle. Treatment with GW9662 (a specific PPARgamma antagonist) prevented all the above PPARgamma-mediated actions. Thus, PPARgamma activation confers neuroprotection after TBI by anti-inflammatory, anti-apoptotic and anti-oxidative mechanisms.