RESUMEN
Axonal pathology is a key contributor to long-term disability in multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS), but the mechanisms that underlie axonal pathology in MS remain elusive. Evidence suggests that axonal pathology is a direct consequence of demyelination, as we and others have shown that the node of Ranvier disassembles following loss of myelin. In contrast to the node of Ranvier, we now show that the axon initial segment (AIS), the axonal domain responsible for action potential initiation, remains intact following cuprizone-induced cortical demyelination. Instead, we find that the AIS is disrupted in the neocortex of mice that develop experimental autoimmune encephalomyelitis (EAE) independent of local demyelination. EAE-induced mice demonstrate profound compromise of AIS integrity with a progressive disruption that corresponds to EAE clinical disease severity and duration, in addition to cortical microglial reactivity. Furthermore, treatment with the drug didox results in attenuation of AIS pathology concomitantly with microglial reversion to a less reactive state. Together, our findings suggest that inflammation, but not demyelination, disrupts AIS integrity and that therapeutic intervention may protect and reverse this pathology. GLIA 2016;64:1190-1209.
Asunto(s)
Segmento Inicial del Axón/fisiología , Axones/patología , Encefalomielitis Autoinmune Experimental/patología , Regulación de la Expresión Génica/fisiología , Microglía/metabolismo , Animales , Animales Modificados Genéticamente , Enfermedades Autoinmunes del Sistema Nervioso/inducido químicamente , Enfermedades Autoinmunes del Sistema Nervioso/tratamiento farmacológico , Enfermedades Autoinmunes del Sistema Nervioso/patología , Antígeno CD11b/genética , Antígeno CD11b/metabolismo , Muerte Celular/fisiología , Células Cultivadas , Cuprizona/toxicidad , Modelos Animales de Enfermedad , Encefalomielitis Autoinmune Experimental/inducido químicamente , Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Encefalomielitis Autoinmune Experimental/inmunología , Regulación de la Expresión Génica/efectos de los fármacos , Ácidos Hidroxámicos/uso terapéutico , Factor Estimulante de Colonias de Macrófagos/genética , Factor Estimulante de Colonias de Macrófagos/metabolismo , Ratones , Ratones Endogámicos C57BL , Microglía/efectos de los fármacos , Inhibidores de la Monoaminooxidasa/toxicidad , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Antígenos Thy-1/genética , Antígenos Thy-1/metabolismo , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
This is an obituary for Richard Hudson Quarles, an internationally renowned neuroscientist, who retired in 2007 after 39 years at the National Institutes of Health, and who died August 9, 2015 in Sandy Spring, Maryland, USA. Richard Hudson Quarles, circa 1984, courtesy of The NIH Record newsletter.
Asunto(s)
Personal de Laboratorio Clínico/historia , National Institutes of Health (U.S.)/historia , Neurociencias/historia , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Estados UnidosRESUMEN
Neurofibromatosis type 1-derived Schwann cells isolated from malignant peripheral nerve sheath tumors (MPNSTs) overexpress PDGF receptor-ß and generate an aberrant intracellular calcium increase in response to PDGF-BB. Using the human MPNST Schwann cell line ST88-14, we demonstrate that, in addition to a transient phosphorylation of Akt, PDGF-BB stimulation produces an atypical sustained phosphorylation of Akt that is dependent on calcium and calmodulin (CaM). The sustained Akt phosphorylation did not occur in PDGF-BB-stimulated normal human Schwann cells or ST88-14 cells stimulated with stem cell factor, whose receptor is also overexpressed in ST88-14 cells. The sustained Akt phosphorylation induced by PDGF-BB was inhibited by pretreatment of the cells with either the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl) ester (BAPTA-AM) or the CaM antagonist W7, whereas the transient portion was not inhibited. Akt also co-immunoprecipitated with CaM in a PDGF-BB-dependent manner, suggesting that direct interaction between Akt and CaM is involved in the sustained phosphorylation of Akt. Furthermore, we provide evidence that anti-apoptotic effects of PDGF-BB on serum-deprived ST88-14 cells can be inhibited by W7, implicating the PDGF-BB-induced activation of calcium/CaM in promoting cell survival, presumably through sustained Akt activation. We conclude that the activation of the calcium/CaM/Akt pathway resulting from stimulation of overexpressed PDGF receptor-ß may contribute to the survival and tumorigenicity of MPNST cells.
Asunto(s)
Inductores de la Angiogénesis/farmacología , Calcio/metabolismo , Calmodulina/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-sis/farmacología , Células de Schwann/metabolismo , Becaplermina , Calmodulina/antagonistas & inhibidores , Línea Celular , Quelantes/farmacología , Ácido Egtácico/análogos & derivados , Ácido Egtácico/farmacología , Inhibidores Enzimáticos/farmacología , Humanos , Neurofibromatosis 1/tratamiento farmacológico , Neurofibromatosis 1/genética , Neurofibromatosis 1/metabolismo , Neurofibromatosis 1/patología , Neurofibromina 1/genética , Fosforilación/efectos de los fármacos , Fosforilación/genética , Proteínas Proto-Oncogénicas c-akt/genética , Receptores del Factor de Crecimiento Derivado de Plaquetas/genética , Receptores del Factor de Crecimiento Derivado de Plaquetas/metabolismo , Células de Schwann/patología , Sulfonamidas/farmacologíaRESUMEN
Malignant peripheral nerve sheath tumors (MPNSTs) are soft-tissue sarcomas of the peripheral nervous system that develop either sporadically or in the context of neurofibromatosis type 1 (NF1). MPNST diagnosis can be challenging and treatment outcomes are poor. We present here a resource consisting of the genomic characterization of 9 widely used human MPNST cell lines for their use in translational research. NF1-related cell lines recapitulated primary MPNST copy number profiles, exhibited NF1, CDKN2A, and SUZ12/EED tumor suppressor gene (TSG) inactivation, and presented no gain-of-function mutations. In contrast, sporadic cell lines collectively displayed different TSG inactivation patterns and presented kinase-activating mutations, fusion genes, altered mutational frequencies and COSMIC signatures, and different methylome-based classifications. Cell lines re-classified as melanomas and other sarcomas exhibited a different drug-treatment response. Deep genomic analysis, methylome-based classification, and cell-identity marker expression, challenged the identity of common MPNST cell lines, opening an opportunity to revise MPNST differential diagnosis.
RESUMEN
Neuregulins (NRGs) are a family of growth factors which bind to the erbB family of tyrosine kinase receptors. The exact nature and interaction of specific NRG isoforms and erbB receptors that occur during the development of the nervous system have not been reported. In order to better understand the role that different NRG isoforms and erbB receptors play in the differentiation, proliferation, and survival of neurons and glial cells, we isolated protein and mRNA from dorsal root ganglia of rat pups between embryonic day (E) 13 and postnatal day (P) 15. The relative expression levels of the NRGs and erbB receptors for the different time points were compared using both Western and RT-PCR analyses. NRG1-type1alpha protein levels were highest at E-13 and then decreased by approximately 40% and remained constant through P-15. In contrast, mRNA levels for NRG1-type1alpha remained constant from E-15 to P-15. The protein levels for NRG1-type 1beta were similar to NRG1-type1alpha at E-13 with an approximate 40% increase in the levels at E-15 and E-17 followed by a decrease to E-13 levels for the remainder of the developmental time periods. The mRNA levels for NRG1-type1beta remained constant from E-15 to P-15. The protein and mRNA expression patterns for each erbB receptor were distinctive. The protein levels for erbB-2 were highest at E-19 while erbB-3 levels were highest at E-17 and E-18. ErbB-4 protein levels were highest at E-13 and decreased through P-15. The developmental pattern for erbB-2 and erbB-4 mRNA levels had no relation to that of the corresponding protein levels while the mRNA levels for erbB-3 were highest at E-17 and E-18 similar to the pattern observed for the erbB-3 protein levels. We concluded that both NRG and erbB expression in dorsal root ganglia are mostly translationally controlled and that NRG1 isoforms and their erbB receptors are not coordinately regulated.
Asunto(s)
Ganglios Espinales/metabolismo , Neurregulina-1/biosíntesis , Animales , Receptores ErbB/biosíntesis , Ganglios Espinales/crecimiento & desarrollo , Regulación del Desarrollo de la Expresión Génica , Isoformas de Proteínas/biosíntesis , Ratas , Receptor ErbB-2/biosíntesis , Receptor ErbB-3/biosíntesis , Receptor ErbB-4RESUMEN
Neuroblastoma (NB), a common pediatric neoplasm, consists of two main cell populations: neuroblastic/ganglionic cells and Schwann cells. NB tumors with abundant Schwannian stroma display a more benign clinical behavior than stroma-poor tumors. Recent studies suggest that Schwann cells influence NB tumor growth via secreted factors that induce differentiation, suppress proliferation, and inhibit angiogenesis. Two angiogenesis inhibitors, pigment epithelium-derived factor and tissue inhibitor of metalloproteinase-2, have been detected in Schwann cell secretions. Here, we isolated another Schwann cell-derived secreted inhibitor of angiogenesis, a 43-kDa protein identified as SPARC (secreted protein acidic and rich in cysteine), an extracellular matrix protein. We found SPARC to be critical for the antiangiogenic phenotype of cultured Schwann cells. We also show that purified SPARC potently inhibits angiogenesis and significantly impairs NB tumor growth in vivo. SPARC may be an effective candidate for the treatment of children with clinically aggressive, Schwannian stroma-poor NB tumors.
Asunto(s)
Inhibidores de la Angiogénesis/fisiología , Neovascularización Patológica/patología , Neuroblastoma/irrigación sanguínea , Osteonectina/fisiología , Células de Schwann/metabolismo , Adulto , Inhibidores de la Angiogénesis/biosíntesis , Inhibidores de la Angiogénesis/metabolismo , Inhibidores de la Angiogénesis/farmacología , Animales , Diferenciación Celular/fisiología , División Celular/fisiología , Movimiento Celular/efectos de los fármacos , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Femenino , Humanos , Ratones , Ratones Desnudos , Neovascularización Patológica/tratamiento farmacológico , Neovascularización Patológica/metabolismo , Neuroblastoma/metabolismo , Neuroblastoma/patología , Osteonectina/biosíntesis , Osteonectina/metabolismo , Osteonectina/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Guillain-Barré syndrome (GBS) is an autoimmune-mediated disease triggered by a preceding infection. A substantial body of evidence implicates antibodies to various gangliosides in subtypes of GBS. A significant proportion of patients with acute demyelinating subset of GBS have IgG antibodies against peripheral nervous system myelin specific neolactogangliosides such as LM1 and Hex-LM1. Although anti-neolactoganglioside antibodies in GBS were described more than two decades ago, their pathogenic role in neuropathy remains unknown due to the lack of suitable experimental models. In this study, we immunized ten guinea pigs with purified LM1 ganglioside mixed with keyhole limpet hemocyanin (KLH) and emulsified in complete Freund's adjuvant (CFA). Control guinea pigs were injected with KLH emulsified in CFA only. The animals were bled every four week intervals. The animals were boosted 3 times every four weeks. Experiments were terminated four months after initial immunization. Nine of 10 guinea pigs immunized with LM1 exhibited antibody responses to LM1. Anti-LM1 IgG titers in nine guinea pigs ranged from 1:400 to 1:12,800 at 16-weeks after initial immunization. Anti-LM1 antibodies were predominantly of IgG2 subclass. One guinea pig with the highest levels of IgG antibodies exhibited mild signs of neuropathy. There was no evidence of demyelination or inflammation in the sciatic nerves of LM1-immunized guinea pigs. Anti-LM1 antibodies bound to rat sciatic nerve myelin and to isolated rat Schwann cells. In summary, our findings suggest that relatively high levels of anti-LM1 IgG antibodies can be induced in guinea pigs and that LM1 is localized in peripheral nerve myelin and in Schwann cells. Further studies are needed to determine the pathogenic potential of anti-neolactoganglioside antibodies in neuropathy.
Asunto(s)
Autoanticuerpos/biosíntesis , Gangliósidos/inmunología , Inmunoglobulina G/biosíntesis , Animales , Autoanticuerpos/metabolismo , Enfermedades Desmielinizantes/diagnóstico , Enfermedades Desmielinizantes/inmunología , Enfermedades Desmielinizantes/patología , Modelos Animales de Enfermedad , Adyuvante de Freund/administración & dosificación , Gangliósidos/administración & dosificación , Síndrome de Guillain-Barré/diagnóstico , Síndrome de Guillain-Barré/inmunología , Síndrome de Guillain-Barré/patología , Cobayas , Hemocianinas/administración & dosificación , Hemocianinas/inmunología , Humanos , Inmunización/métodos , Inmunoglobulina G/metabolismo , Células de Schwann/inmunología , Células de Schwann/metabolismo , Células de Schwann/patología , Nervio Ciático/inmunología , Nervio Ciático/patologíaRESUMEN
In the developing PNS, axonal neuregulin-1 (NRG1) type III is the key determinant for myelination. However, the specific role for NRG1 (III) in the CNS has not been established. To address this issue, isotype-specific antibodies were generated, characterized, and used for the immunofluorescent localization of NRG1 (III) in the developing and adult CNS of rat. In contrast to adult peripheral nerve, which showed robust axonal staining, no immunoreactivity was observed in CNS myelinated tracts during the period of active myelination or in the adult CNS. Surprisingly, NRG1 (III) was prominently expressed on dendrites and soma in both the developing and adult CNS. These findings were corroborated through the subcellular fractionation of adult rat brain combined with an immunoblotting analysis. The immunolocalization of NRG1 (III) suggests that it plays a novel role in the myelination fate of CNS axons possibly through undetermined roles in neuronal maturation, or dendritic development and activation.
Asunto(s)
Sistema Nervioso Central/metabolismo , Neurregulina-1/biosíntesis , Neurogénesis/fisiología , Neuronas/metabolismo , Sistema Nervioso Periférico/metabolismo , Animales , Especificidad de Anticuerpos , Femenino , Técnica del Anticuerpo Fluorescente , Immunoblotting , Inmunoprecipitación , Masculino , Ratones , Neurregulina-1/análisis , Isoformas de Proteínas/análisis , Isoformas de Proteínas/biosíntesis , Ratas , Ratas Sprague-DawleyRESUMEN
The ability of an AEF (axolemma-enriched fraction) to influence the proliferation, survival and differentiation of OPC (oligodendrocyte progenitor cells) was evaluated. Following addition of AEF to cultured OPC, the AEF associated with the outer surface of OPC so that subsequent metabolic events were likely mediated by direct AEF-OPC contact. Addition of AEF to the cultured OPC resulted in a dose- and time-dependent increase in proliferation that was partially dependent on Akt (protein kinase B) and MAPK (mitogen-activated protein kinase) activation. The major mitogen in an AEF-SE (soluble 2.0 M NaCl extract of the AEF) was identified as aFGF (acidic fibroblast growth factor) and accounted for 50% of the mitogenicity. The remaining 50% of the mitogenicity had properties consistent with bFGF (basic fibroblast growth factor) but was not unequivocally identified. Under conditions that limit the survival of OPC in culture, AEF treatment prolonged the survival of the OPC. Antigenic and morphological examination of the AEF-treated OPC indicated that the AEF treatment helped the OPC survive in a more immature state. The potential downstream metabolic pathways potentially activated in OPC by AEF and the consequences of these activated pathways are discussed. The results of these studies are consistent with the view that direct contact of axons with OPC stimulates their proliferation and survival while preventing their differentiation.
Asunto(s)
Estructuras Celulares/metabolismo , Oligodendroglía/fisiología , Células de Schwann/química , Células Madre/efectos de los fármacos , Células Madre/fisiología , Animales , Animales Recién Nacidos , Recuento de Células/métodos , Diferenciación Celular/fisiología , Proliferación Celular , Células Cultivadas , Cromatografía en Agarosa/métodos , Calor , Proteínas Quinasas Activadas por Mitógenos , Mitógenos/farmacología , Neuronas/fisiología , Proteínas Proto-Oncogénicas c-akt , Ratas , Ratas Sprague-Dawley , Células de Schwann/metabolismo , Células Madre/inmunología , Tripsina/farmacologíaRESUMEN
We have shown previously that prostaglandin E(2) (PGE(2)) and prostaglandin I(2) (PGI(2)) are each produced in an explant model of peripheral nerve injury. We report that IP prostanoid receptor mRNA and protein are present in primary rat Schwann cells. IP prostanoid receptor stimulation using prostacyclin produced an elevation in intracellular cyclic AMP concentration ([cAMP](i)) in primary Schwann cells. Peak [cAMP](i) was observed between 5-15 min of stimulation followed by a gradual recovery toward basal level. Phosphorylation of cyclic AMP-response element binding protein (CREB) on Ser(133) was also detected after IP prostanoid receptor stimulation and CREB phosphorylation was inhibited completely by the protein kinase A inhibitor, H-89. Intracellular calcium levels were not affected by IP prostanoid receptor stimulation. Unlike forskolin, IP prostanoid receptor stimulation did not significantly augment Schwann cell proliferation in response to growth factor treatment. However, IP prostanoid receptor stimulation increased the number of Schwann cells that were able to generate a calcium transient in response to P2 purinergic receptor activation. These findings suggest that signaling via the IP prostanoid receptor may by relevant to Schwann cell biology in vivo.
Asunto(s)
AMP Cíclico/metabolismo , Regulación de la Expresión Génica/fisiología , Líquido Intracelular/metabolismo , Receptores de Prostaglandina/metabolismo , Células de Schwann/metabolismo , Análisis de Varianza , Animales , Animales Recién Nacidos , Calcio/metabolismo , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos , Epoprostenol/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Líquido Intracelular/efectos de los fármacos , Isoquinolinas/farmacología , Fosforilación/efectos de los fármacos , Inhibidores de Agregación Plaquetaria/farmacología , ARN Mensajero/metabolismo , Ratas , Receptores de Prostaglandina/genética , Células de Schwann/efectos de los fármacos , Nervio Ciático/citología , Serina/metabolismo , Sulfonamidas/farmacologíaRESUMEN
Plexiform neurofibromas are peripheral nerve sheath tumors that arise frequently in neurofibromatosis type 1 (NF1) and have a risk of malignant progression. Past efforts to establish xenograft models for neurofibroma involved the implantation of tumor fragments or heterogeneous primary cultures, which rarely achieved significant tumor growth. We report a practical and reproducible animal model of plexiform-like neurofibroma by xenograft of an immortal human NF1 tumor-derived Schwann cell line into the peripheral nerve of scid mice. The S100 and p75 positive sNF94.3 cell line was shown to possess a normal karyotype and have apparent full-length neurofibromin by Western blot. These cells were shown to have a constitutional NF1 microdeletion and elevated Ras-GTP activity, however, suggesting loss of normal neurofibromin function. Localized intraneural injection of the cell line sNF94.3 produced consistent and slow growing tumors that infiltrated and disrupted the host nerve. The xenograft tumors resembled plexiform neurofibromas with a low rate of proliferation, abundant extracellular matrix (hypocellularity), basal laminae, high vascularity, and mast cell infiltration. The histologic features of the developed tumors were particularly consistent with those of human plexiform neurofibroma as well. Intraneural xenograft of sNF94.3 cells enables the precise initiation of intraneural, plexiform-like tumors and provides a highly reproducible model for the study of plexiform neurofibroma tumorigenesis. This model facilitates testing of potential therapeutic interventions, including angiogenesis inhibitors, in a relevant cellular environment.
Asunto(s)
Línea Celular Tumoral , Neoplasias Pulmonares/patología , Neurofibromatosis 1/patología , Células de Schwann/citología , Adulto , Animales , Western Blotting , Femenino , Humanos , Ratones , Ratones SCID , Trasplante de Neoplasias/métodos , Proteínas del Tejido Nervioso/metabolismo , Neurofibromina 1/genética , Células de Schwann/enzimología , Trasplante Heterólogo/métodos , Proteínas ras/metabolismoRESUMEN
CD1d-restricted NKT cells expressing invariant TCR alpha-chains (iNKT cells) produce both proinflammatory and anti-inflammatory cytokines rapidly upon activation, and are believed to play an important role in both host defense and immunoregulation. To address the potential implications of iNKT cell responses for infectious or inflammatory diseases of the nervous system, we investigated the expression of CD1d in human peripheral nerve. We found that CD1d was expressed on the surface of Schwann cells in situ and on primary or immortalized Schwann cell lines in culture. Schwann cells activated iNKT cells in a CD1d-dependent manner in the presence of alpha-galactosylceramide. Surprisingly, the cytokine production of iNKT cells stimulated by alpha-galactosylceramide presented by CD1d+ Schwann cells showed a predominance of Th2-associated cytokines such as IL-5 and IL-13 with a marked deficiency of proinflammatory Th1 cytokines such as IFN-gamma or TNF-alpha. Our findings suggest a mechanism by which iNKT cells may restrain inflammatory responses in peripheral nerves, and raise the possibility that the expression of CD1d by Schwann cells could be relevant in the pathogenesis of infectious and inflammatory diseases of the peripheral nervous system.
Asunto(s)
Antígenos CD1/análisis , Comunicación Celular/inmunología , Células Asesinas Naturales/inmunología , Células de Schwann/inmunología , Antígenos CD1d , Células Cultivadas , Técnicas de Cocultivo , Citocinas/análisis , Galactosilceramidas/farmacología , Humanos , Inmunidad , Inflamación , Células Asesinas Naturales/citología , Enfermedades del Sistema Nervioso/inmunología , Enfermedades del Sistema Nervioso/patología , Células de Schwann/química , Células de Schwann/citología , Linfocitos TRESUMEN
Neurofibromatosis type 1 (NF1) is a genetic disease caused by the loss of neurofibromin, which can lead to formation of highly invasive malignant peripheral nerve sheath tumors (MPNST). We characterized platelet-derived growth factor-beta (PDGF-beta) receptor expression levels and signal transduction pathways in NF1 MPNST cell lines and compared them with the expression of PDGF-beta receptors in normal human Schwann cells (nhSC). As examined by Western blotting, PDGF-beta receptor expression levels were similar in nhSC and NF1 MPNST cell lines. MAPK and Akt also were phosphorylated in both cell types to a similar degree in response to PDGF B chains (PDGF-BB). However, increased intracellular calcium (Ca2+) levels in response to PDGF-BB were observed only in the NF1 MPNST cell lines; nhSC did not show any increase in intracellular calcium when stimulated with PDGF-BB. The calcium response in NF1 MPNST cell lines was blocked with thapsigargin, suggesting that the PDGF-BB-stimulated increases in intracellular calcium originated in the internal compartment of the cell rather than reflecting influx of calcium from the extracellular compartment. Calmodulin kinase II (CAMKII) is phosphorylated in response to PDGF-BB in the NF1 MPNST cell lines, whereas no phosphorylation of CAMKII was observed in nhSCs. The decreased growth of NF1 MPNST cell lines after treatment with a CAMKII inhibitor is consistent with the view that aberrant activation of the calcium-signaling pathway by PDGF-BB contributes to the formation of MPNST in NF1 patients.
Asunto(s)
Señalización del Calcio/fisiología , Neoplasias de la Vaina del Nervio/metabolismo , Neurofibromatosis 1/metabolismo , Factor de Crecimiento Derivado de Plaquetas/farmacología , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Células de Schwann/metabolismo , Adulto , Becaplermina , Calcio/metabolismo , Señalización del Calcio/efectos de los fármacos , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina , Proteínas Quinasas Dependientes de Calcio-Calmodulina/antagonistas & inhibidores , Proteínas Quinasas Dependientes de Calcio-Calmodulina/metabolismo , Línea Celular , Transformación Celular Neoplásica/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Sistema de Señalización de MAP Quinasas/fisiología , Masculino , Persona de Mediana Edad , Neoplasias de la Vaina del Nervio/tratamiento farmacológico , Neoplasias de la Vaina del Nervio/fisiopatología , Neurofibromatosis 1/fisiopatología , Neurofibromina 1/biosíntesis , Fosforilación/efectos de los fármacos , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-akt , Proteínas Proto-Oncogénicas c-sis , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/efectos de los fármacos , Células de Schwann/efectos de los fármacos , Células de Schwann/patologíaRESUMEN
The growth factor receptor c-Kit has several well-characterized functions during the development of numerous cell types, including red blood cells, mast cells, and melanocytes. Its role in Schwann cells has been described in transformed cells derived from malignant peripheral nerve sheath tumors from patients with neurofibromatosis type 1 (NF1 MPNST; Badache et al. [1998] Oncogene 17:795-800). However, c-Kit functions have not been investigated in normal Schwann cells. We report here that neonatal rat Schwann cells express low c-Kit levels, whereas expression levels for c-Kit are high for Schwann cells derived from MPNST of NF1 patients. In addition, c-Kit expression is not detectable in normal adult human Schwann cells. Although the c-Kit ligand stem cell factor (SCF) induces the phosphorylation of protein kinase B (or Akt) and prevents apoptosis in Schwann cells, SCF has no effect on the proliferation or differentiation of Schwann cells.
Asunto(s)
Regulación Neoplásica de la Expresión Génica/fisiología , Expresión Génica/fisiología , Neurofibromatosis , Proteínas Proto-Oncogénicas c-kit/metabolismo , Células de Schwann/metabolismo , Análisis de Varianza , Animales , Animales Recién Nacidos , Apoptosis/efectos de los fármacos , Northern Blotting , Western Blotting/métodos , Bromodesoxiuridina/metabolismo , Recuento de Células/métodos , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Cromonas/farmacología , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Inhibidores Enzimáticos/farmacología , Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Etiquetado Corte-Fin in Situ/métodos , Morfolinas/farmacología , Neurregulina-1/farmacología , Neurofibromatosis/metabolismo , Neurofibromatosis/patología , Neurofibromina 1/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-kit/genética , Proteínas Proto-Oncogénicas c-kit/farmacología , ARN Mensajero/biosíntesis , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Células de Schwann/efectos de los fármacos , Factores de TiempoRESUMEN
One up-and-coming approach to controlling health care costs is complementary health care, which does not rely on advances in high-tech, invasive technology or expensive new pharmaceuticals, but rather focuses much more on the high-touch, direct practitioner care. It often offers lower cost alternatives to traditional medicine.
Asunto(s)
Terapias Complementarias/economía , Planes de Asistencia Médica para Empleados/organización & administración , Control de Costos , Medicina Basada en la Evidencia , Promoción de la Salud , Humanos , Estilo de Vida , Poder Psicológico , Estados UnidosRESUMEN
Axonal loss is well correlated with functional deficits in Multiple Sclerosis (MS); however, the molecular mechanisms that underlie this axonal loss are not understood. In this review we summarize evidence that antibodies to axolemma-enriched fractions (AEF) isolated from CNS myelinated axons may play a role in axonal destruction. AEF contains potent antigens that elicit high-titer antisera, which destroy neurites in vitro, prevent neurite outgrowth, cause reactive changes in the neuronal cell bodies of origin and prevent myelination. We propose that these AEF antigens are cryptic because they are shielded from immune surveillance in vivo via the tightly sealed paranodal loops of myelin. Antibodies to AEF are found in cerebrospinal fluid (CSF) and sera of MS patients at higher levels compared with CSF or sera derived from patients with other neurological diseases. The potential identity of these cryptic antigens and their role in the axonal destruction characteristic of MS is discussed.
Asunto(s)
Antígenos/inmunología , Axones/inmunología , Axones/patología , Esclerosis Múltiple/inmunología , Esclerosis Múltiple/patología , Autoanticuerpos/inmunología , HumanosRESUMEN
Sciatic nerve explants cultured either alone or in the presence of peritoneal macrophages were used to study prostaglandin E(2) (PGE(2)) and 6-keto-PGF(1alpha) production following traumatic peripheral nerve injury. Although barely detectable at early time points (1-3 h in vitro), the production of PGE(2) and 6-keto-PGF(1alpha) by sciatic nerve explants increased significantly after 18 h and remained elevated for up to 96 h. The cyclooxygenase-2 (COX-2) selective inhibitor, NS-398, inhibited PGE(2) and 6-keto-PGF(1alpha) production by injured sciatic nerve in a dose-dependent manner. Consistent with the observed effect of NS-398, peripheral nerve explants, as well as Schwann cells and perineural fibroblasts cultured from neonatal sciatic nerve, each contained COX-2 immunoreactivity after 24 h in vitro. Both Schwann cells and perineural fibroblasts produced significant amounts of PGE(2) and 6-keto-PGF(1alpha); but only in the presence of arachidonic acid. As observed for injured sciatic nerve, the production of PGE(2) and 6-keto-PGF(1alpha) by primary Schwann cells and perineural fibroblasts was completely inhibited by NS-398. Compared to macrophages cultured alone, macrophages cultured in the presence of sciatic nerve explants produced large amounts of PGE(2), whereas the level of 6-keto-PGF(1alpha) was unchanged. In contrast, macrophages treated with adult sciatic nerve homogenate did not produce significant amounts of either PGE(2) or 6-keto-PGF(1alpha) during the entire course of treatment. We conclude that injured sciatic nerves produce PGE(2) and 6-keto-PGF(1alpha) by a mechanism involving COX-2 activity and that macrophages produce large amounts of PGE(2) in response to soluble factors produced by injured nerve but not during the phagocytosis of peripheral nerve debris.
Asunto(s)
6-Cetoprostaglandina F1 alfa/metabolismo , Dinoprostona/metabolismo , Nervio Ciático/lesiones , Nervio Ciático/metabolismo , Animales , Células Cultivadas , Medios de Cultivo Condicionados/farmacología , Ciclooxigenasa 2 , Fibroblastos/citología , Fibroblastos/metabolismo , Técnicas In Vitro , Isoenzimas/metabolismo , Macrófagos/citología , Macrófagos/metabolismo , Fagocitosis/fisiología , Prostaglandina-Endoperóxido Sintasas/metabolismo , Ratas , Ratas Sprague-Dawley , Células de Schwann/citología , Células de Schwann/metabolismo , Nervio Ciático/citología , SolubilidadRESUMEN
Primary and immortalized cultured Schwann cells are commonly utilized in analyses of myelin gene promoters, but few lines are well-characterized in terms of their endogenous expression of myelin genes. This is particularly significant in that cultured Schwann cells typically do not express myelin genes at levels comparable to those observed in vivo. In this study, the steady-state levels of mRNA and protein for five Schwann cell markers (PMP22, P0, MBP, MAG, and LNGF-R) were assessed in primary Schwann cells and six representative Schwann cell lines (RT4-D6P2T, JS-1, RSC96, R3, S16, and S16Y). RT4-D6P2T and S16 cells were the most similar to myelinating Schwann cells based on their comparatively high expression of PMP22 and P0 mRNA. Both RT4-D6P2T and S16 also expressed P0 protein. In addition, the previously reported P1-A positive regulatory region from the myelination-specific PMP22 promoter demonstrated significant activity in both these cell lines. However, nuclear proteins that interacted with P1-A were different in extracts prepared from RT4-D6P2T and S16 cells. Primary Schwann cells expressed myelin proteins at levels that were equal or less than those observed with the RT4-D6P2T and S16 lines, indicating that primary Schwann cells are not necessarily better than immortalized Schwann cells as model systems for the study of myelin gene regulation. The data presented here demonstrate that cultured Schwann cells used to study myelin gene promoters have to be carefully selected on the basis of the endogenous level of expression of the myelin gene under study.