RESUMEN

OBJECTIVE: To quantify the isoprostane 8,12-iso-iPF2alpha-VI in brain tissues obtained from patients with AD, patients with frontotemporal dementia (FTD), and controls. BACKGROUND: Enhanced brain oxidative stress with secondary damage to cellular macromolecules may play a role in the pathogenesis of AD and FTD. The isoprostane 8,12-iso-iPF2alpha-VI is a specific and sensitive marker of in vivo lipid peroxidation and is increased in AD. METHODS: Levels of this isoprostane were determined by gas chromatography/negative ion chemical ionization mass spectrometry. RESULTS: Levels of 8,12-iso-iPF2alpha-VI were markedly elevated in both frontal and temporal cortex of AD brains compared to the corresponding areas of FTD and controls. No significant difference in brain 8,12-iso-iPF2alpha-VI levels for any regions considered was observed between FTD and controls. CONCLUSIONS: Lipid peroxidation is a feature of AD, but not FTD. The generation of 8,12-iso-iPF(2alpha)-VI in the brain is not a general or final common pathway of neurodegeneration, but may be relatively specific for disease processes in AD and not FTD.

Asunto(s)

Enfermedad de Alzheimer/metabolismo , Química Encefálica , Demencia/metabolismo , Dinoprost/análogos & derivados , Dinoprost/análisis , Peroxidación de Lípido , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/patología , Biomarcadores , Demencia/clasificación , Demencia/patología , Femenino , Cromatografía de Gases y Espectrometría de Masas , Humanos , Masculino , Persona de Mediana Edad , Degeneración Nerviosa , Estrés Oxidativo , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/patología , Enfermedad de Pick/metabolismo , Enfermedad de Pick/patología , Parálisis Supranuclear Progresiva/metabolismo , Parálisis Supranuclear Progresiva/patología

RESUMEN

We examined spinal cords of neurodegenerative disease patients and controls living on the Island of Guam and in the continental United States. These patients had pathologically confirmed parkinsonism dementia-complex (PDC) with or without amyotrophic lateral sclerosis (ALS), or Alzheimer disease (AD), respectively. Nearly all of the spinal cords examined from both groups of patients contained neurofibrillary tangles (NFT). The immunohistochemical profile of these NFTs indicates that they are composed of hyperphosphorylated tau protein like their counterparts in the brains of these patients. Western blot analysis confirmed this by revealing that sarcosyl insoluble tau in spinal cord extracts from patients with NFTs exhibited the presence of all 6 tau isoforms similar to that from AD and ALS/PDC cortical gray matter.

Asunto(s)

Enfermedad de Alzheimer/patología , Esclerosis Amiotrófica Lateral/patología , Ovillos Neurofibrilares/patología , Médula Espinal/patología , Anciano , Anciano de 80 o más Años , Anticuerpos , Western Blotting , Femenino , Guam , Humanos , Masculino , Microscopía Electrónica , Persona de Mediana Edad , Neuronas/química , Neuronas/patología , Neuronas/ultraestructura , Médula Espinal/química , Estados Unidos , Proteínas tau/análisis , Proteínas tau/inmunología

RESUMEN

Insights into mechanisms of familial Alzheimer's disease (AD) caused by genetic mutations have emerged rapidly compared to sporadic AD. Indeed, despite identification of several sporadic AD risk factors, it remains enigmatic how or why they predispose to neurodegenerative disease. For example, traumatic brain injury (TBI) predisposes to AD, and recurrent TBI in career boxers may cause a progressive memory disorder associated with AD-like brain pathology known as dementia pugilistica (DP). Although the reasons for this are unknown, repeated TBI may cause DP by mechanisms similar to those involved in AD. To investigate this possibility, we compared the molecular profile of tau pathologies in DP with those in AD and showed that the same tau epitopes map to filamentous tau inclusions in AD and DP brains, while the abnormal tau proteins isolated from DP brains are indistinguishable from the six abnormally phosphorylated brain tau isoforms in AD brains. Thus, these data suggest that recurrent TBI may cause DP by activating pathological mechanisms similar to those that cause brain degeneration due to accumulations of filamentous tau lesions in AD, and similar, albeit attenuated, activation of these processes by a single TBI may increase susceptibility to sporadic AD decades after the event.

Asunto(s)

Enfermedad de Alzheimer/metabolismo , Traumatismos en Atletas/metabolismo , Boxeo/lesiones , Lesiones Encefálicas/metabolismo , Sistema Nervioso Central/metabolismo , Neuronas/metabolismo , Proteínas tau/metabolismo , Anciano , Enfermedad de Alzheimer/patología , Traumatismos en Atletas/patología , Traumatismos en Atletas/fisiopatología , Western Blotting , Lesiones Encefálicas/patología , Lesiones Encefálicas/fisiopatología , Sistema Nervioso Central/lesiones , Sistema Nervioso Central/patología , Epítopos/inmunología , Humanos , Inmunohistoquímica , Masculino , Ovillos Neurofibrilares/metabolismo , Ovillos Neurofibrilares/patología , Neuronas/patología , Fosforilación , Isoformas de Proteínas/metabolismo

RESUMEN

Dementia lacking distinctive histopathology (DLDH) or frontotemporal lobe degeneration (FTLD) is the most common neuropathological diagnosis for sporadic frontotemporal dementias (FTDs). The hallmarks of DLDH are neuron loss and gliosis in the absence of any disease-specific brain lesion. Similar brain pathology is also seen in a familial FTD pedigree known as hereditary dysphasic disinhibition dementia 2 (HDDD2). Abnormality in the function or isoform composition of the microtubule binding protein tau is a prominent feature in the brains of many patients with sporadic and hereditary FTDs. Therefore, we studied the tau protein in different brain regions from DLDH and HDDD2 patients. Our results indicate that a selective loss of all six tau isoforms, but not tau mRNA, occurs in these brains compared to normal control and Alzheimer's disease brains. Loss of tau protein was identified by Western blot analysis of protein extracts from DLDH and HDDD2 brains in regions both with and without neuronal degeneration. Functionally, this loss of tau protein may be equivalent to pathogenic mutations in the tau gene identified in familial FTD with parkinsonism linked to chromosome 17 (FTDP-17). Thus, DLDH and HDDD2 are novel tauopathies with a unique mechanism of pathogenesis. The presence of tau mRNA in these brains suggests that the level of tau protein may be controlled posttranscriptionally, at the level of either translation or mRNA stability.

Asunto(s)

Encéfalo/patología , Demencia/patología , Proteínas tau/análisis , Anciano , Anciano de 80 o más Años , Western Blotting , Demencia/genética , Femenino , Lóbulo Frontal/patología , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Lóbulo Temporal/patología

RESUMEN

It is unclear how tau gene mutations cause frontotemporal dementia (FTD) with parkinsonism linked to chromosome 17 (FTDP-17), but those in exon 10 (E10) or the following intron may be pathogenic by altering E10 splicing, perturbing the normal 1:1 ratio of four versus three microtubule-binding repeat tau (4R:3R tau ratio) and forming tau inclusions. We report on a 55-year old woman with frontotemporal dementia and a family history of FTDP-17 in whom we found a novel E12 (Glu342Val) tau gene mutation, prominent frontotemporal neuron loss, intracytoplasmic tau aggregates, paired helical tau filaments, increased 4R tau messenger RNA, increased 4R tau without E2 or E3 inserts, decreased 4R tau with these inserts, and a 4R:3R tau ratio greater than 1 in gray and white matter. Thus, this novel Glu342Val mutation may cause FTDP-17 by unprecedented mechanisms that alter splicing of E2, E3, and E10 to preferentially increase 4R tau without amino terminal inserts and promote aggregation of tau filaments into cytopathic inclusions.

Asunto(s)

Encéfalo/patología , Demencia/genética , Demencia/patología , Mutación/genética , Proteínas tau/genética , Demencia/psicología , Femenino , Lóbulo Frontal/patología , Humanos , Inmunohistoquímica , Imagen por Resonancia Magnética , Microscopía Inmunoelectrónica , Persona de Mediana Edad , Pruebas Neuropsicológicas , Linaje , Lóbulo Temporal/patología

RESUMEN

Frontotemporal dementia is a heterogeneous, often inherited disorder that typically presents with the insidious onset of behavioral and personality changes. Two genetic loci have been identified and mutations in tau have been causally implicated in a subset of families linked to one of these loci on chromosome 17q21-22. In this study, linkage analysis was performed in a large pedigree, the MN family, suggesting chromosome 17q21-22 linkage. Mutational analysis of the tau coding region identified a C-to-T change in exon 10 that resulted in the conversion of proline to a leucine (P301L) that segregated with frontotemporal dementia in this family. The clinical and pathological findings in the MN family emphasize the significant overlap between Pick's disease, corticobasal degeneration, and frontotemporal dementia and challenge some of the current dogma surrounding this condition. Pathological studies of two brains from affected members of Family MN obtained at autopsy demonstrate numerous tau-positive inclusions that were most prominent in the frontal lobes, anterior temporal lobes, and brainstem structures, as well as Pick-like bodies and associated granulovacuolar degeneration. These Pick-like bodies were observed in 1 patient with motor neuron disease. Because exon 10 is present only in tau mRNA coding for a protein with four microtubule binding repeats (4R), this mutation should selectively affect 4Rtau isoforms. Indeed, immunoblotting demonstrated that insoluble 4Rtau is selectively aggregated in both gray and white matter of affected individuals. Although there was significant pathological similarity between the 2 cases, the pattern of degenerative changes and tau-positive inclusions was not identical, suggesting that other genetic or epigenetic factors can significantly modify the regional topology of neurodegeneration in this condition.

Asunto(s)

Demencia/genética , Mutación/genética , Enfermedad de Parkinson/genética , Proteínas tau/análisis , Encéfalo/patología , Demencia/patología , Lóbulo Frontal , Ligamiento Genético/genética , Genotipo , Humanos , Persona de Mediana Edad , Enfermedad de Parkinson/patología , Linaje , Fenotipo , Lóbulo Temporal

RESUMEN

Tau proteins aggregate as cytoplasmic inclusions in a number of neurodegenerative diseases, including Alzheimer's disease and hereditary frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). Over 10 exonic and intronic mutations in the tau gene have been identified in about 20 FTDP-17 families. Analyses of soluble and insoluble tau proteins from brains of FTDP-17 patients indicated that different pathogenic mutations differentially altered distinct biochemical properties and stoichiometry of brain tau isoforms. Functional assays of recombinant tau proteins with different FTDP-17 missense mutations implicated all but one of these mutations in disease pathogenesis by reducing the ability of tau to bind microtubules and promote microtubule assembly.

Asunto(s)

Encéfalo/metabolismo , Demencia/genética , Microtúbulos/metabolismo , Enfermedad de Parkinson Secundaria/genética , Proteínas tau/genética , Proteínas tau/metabolismo , Empalme Alternativo , Cerebelo/metabolismo , Cromosomas Humanos Par 17 , Demencia/metabolismo , Lóbulo Frontal/metabolismo , Humanos , Mutación , Mutación Missense , Enfermedad de Parkinson Secundaria/metabolismo , Fosforilación , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Recombinantes/metabolismo , Solubilidad , Síndrome , Proteínas tau/química

RESUMEN

Membrane-associated signals expressed in restricted domains of the developing cerebral cortex may mediate axon target recognition during the establishment of thalamocortical projections, which form in a highly precise manner during development. To test this hypothesis, we first analyzed the outgrowth of thalamic explants from limbic and nonlimbic nuclei on membrane substrates prepared from limbic cortex and neocortex. The results show that different thalamic fiber populations are able to discriminate between membrane substrates prepared from target and nontarget cortical regions. A candidate molecule that could mediate selective choice in the thalamocortical system is the limbic system-associated membrane protein (LAMP), which is an early marker of cortical and subcortical limbic regions (Pimenta et al.,1995) that can promote outgrowth of limbic axons. Limbic thalamic and cortical axons showed preferences for recombinant LAMP (rLAMP) in a stripe assay. Incubation of cortical membranes with an antibody against LAMP prevented the ability of limbic thalamic fibers to distinguish between membranes from limbic cortex and neocortex. Strikingly, nonlimbic thalamic fibers also responded to LAMP, but in contrast to limbic thalamic fibers, rLAMP inhibited branch formation and acted as a repulsive axonal guidance signal for nonlimbic thalamic axons. The present studies indicate that LAMP fulfills a role as a selective guidance cue in the developing thalamocortical system.

Asunto(s)

Química Encefálica/fisiología , Sistema Límbico/citología , Neocórtex/citología , Tálamo/citología , Animales , Axones/fisiología , Células CHO , Moléculas de Adhesión Celular Neuronal/genética , Movimiento Celular/fisiología , Cricetinae , Femenino , Proteínas Ligadas a GPI , Regulación del Desarrollo de la Expresión Génica , Sistema Límbico/química , Sistema Límbico/embriología , Neocórtex/química , Neocórtex/embriología , Vías Nerviosas , Embarazo , Ratas , Ratas Sprague-Dawley , Tálamo/química , Tálamo/embriología

RESUMEN

Pallido-ponto-nigral degeneration (PPND) is one of the most well characterized familial neurodegenerative disorders linked to chromosome 17q21-22. These hereditary disorders are known collectively as frontotemporal dementia (FTD) and parkinsonism linked to chromosome 17 (FTDP-17). Although the clinical features and associated regional variations in the neuronal loss observed in different FTDP-17 kindreds are diverse, the diagnostic lesions of FTDP-17 brains are tau-rich filaments in the cytoplasm of specific subpopulations of neurons and glial cells. The microtubule associated protein (tau) gene is located on chromosome 17q21-22. For these reasons, we investigated the possibility that PPND and other FTDP-17 syndromes might be caused by mutations in the tau gene. Two missense mutations in exon 10 of the tau gene that segregate with disease, Asn279(Lys) in the PPND kindred and Pro301(Leu) in four other FTDP-17 kindreds, were found. A third mutation was found in the intron adjacent to the 3' splice site of exon 10 in patients from another FTDP-17 family. Transcripts that contain exon 10 encode tau isoforms with four microtubule (MT)-binding repeats (4Rtau) as opposed to tau isoforms with three MT-binding repeats (3Rtau). The insoluble tau aggregates isolated from brains of patients with each mutation were analyzed by immunoblotting using tau-specific antibodies. For each of three mutations, abnormal tau with an apparent Mr of 64 and 69 was observed. The dephosphorylated material comigrated with tau isoforms containing exon 10 having four MT-binding repeats but not with 3Rtau. Thus, the brains of patients with both the missense mutations and the splice junction mutation contain aggregates of insoluble 4Rtau in filamentous inclusions, which may lead to neurodegeneration.

Asunto(s)

Cromosomas Humanos Par 17 , Demencia/genética , Globo Pálido/patología , Enfermedades Neurodegenerativas/genética , Enfermedad de Parkinson/genética , Mutación Puntual , Puente/patología , Sustancia Negra/patología , Proteínas tau/genética , Adulto , Edad de Inicio , Anciano , Empalme Alternativo , Secuencia de Aminoácidos , Mapeo Cromosómico , Demencia/patología , Ligamiento Genético , Humanos , Intrones , Persona de Mediana Edad , Datos de Secuencia Molecular , Enfermedades Neurodegenerativas/patología , Enfermedad de Parkinson/patología , Secuencias Repetitivas de Aminoácido , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Proteínas tau/química

RESUMEN

The ability of cell adhesion molecules (CAMs) to transduce cell surface signals into intracellular responses is critical for developing neurons, particularly during axonal pathfinding and targeting. It has been suggested that different CAMs can promote neuronal outgrowth via activation of common neuronal CAM-specific second-messenger pathways, although the elements involved in this cascade could differ. Limbic system-associated membrane protein (LAMP), a member of the Ig superfamily, is a molecule that promotes cell adhesion and neurite outgrowth from specific populations of fetal neurons. In the present study, we show that LAMP can induce several types of calcium (Ca2+) signals. Neurite outgrowth is promoted if fetal hippocampal neurons are grown on lamp-transfected CHO cells. This LAMP-induced outgrowth of neurons is mediated in part through activation of L-type Ca channels. Application of soluble LAMP to cultures of fetal hippocampal neurons caused a sustained (up to 60 min) elevation of intracellular Ca2+ as measured by fluo-3 fluorescence on a confocal microscope. The number of responding hippocampal neurons was initially low, but increased with age in culture and the [Ca2+]i elevation was only partially decreased by an L-type Ca(2+)-channel blocker. In contrast, at all times in culture, only a small fraction of neurons from visual cortex responded to LAMP application and only with transient elevation of cytosolic Ca2+ (< 15 min). Based on these observations, LAMP appears to function primarily through homophilic interactions and acts in part by modulating intracellular Ca2+ levels during neurite outgrowth by increasing the Ca2+ influx through L-type calcium channels, but has additional effects on intracellular Ca2+ signaling at later developmental stages.

Asunto(s)

Calcio/metabolismo , Moléculas de Adhesión Celular Neuronal/farmacología , Membranas Intracelulares/metabolismo , Neuritas/efectos de los fármacos , Neuritas/fisiología , Neuronas/metabolismo , Animales , Células CHO , Bloqueadores de los Canales de Calcio/farmacología , Cricetinae , Electrofisiología , Feto/citología , Proteínas Ligadas a GPI , Concentración Osmolar , Cloruro de Potasio/farmacología , Ratas/embriología , Proteínas Recombinantes/farmacología

RESUMEN

The formation of brain circuits requires molecular recognition between functionally related neurons. We report the cloning of a molecule that participates in these interactions. The limbic system-associated membrane protein (LAMP) is an immunoglobulin (Ig) superfamily member with 3 Ig domains and a glycosyl-phosphatidylinositol anchor. In the developing forebrain, lamp is expressed mostly by neurons comprising limbic-associated cortical and subcortical regions that function in cognition, emotion, memory, and learning. The unique distribution of LAMP reflects its functional specificity. LAMP-transfected cells selectively facilitate neurite outgrowth of primary limbic neurons. Most striking, administration of anti-LAMP in vivo results in abnormal growth of the mossy fiber projection from developing granule neurons in the dentate gyrus of the hippocampal formation, suggesting that LAMP is essential for proper targeting of this pathway. Rather than being a general guidance cue, LAMP likely serves as a recognition molecule for the formation of limbic connections.

Asunto(s)

Moléculas de Adhesión Celular Neuronal/fisiología , Sistema Límbico/química , Familia de Multigenes , Proteínas del Tejido Nervioso/fisiología , Secuencia de Aminoácidos , Animales , Axones , Células CHO , Adhesión Celular , Moléculas de Adhesión Celular Neuronal/química , Moléculas de Adhesión Celular Neuronal/genética , Células Cultivadas , Clonación Molecular , Cricetinae , Cricetulus , Proteínas Ligadas a GPI , Genes , Glicosilfosfatidilinositoles , Hipocampo/química , Hipocampo/crecimiento & desarrollo , Hipocampo/ultraestructura , Sistema Límbico/embriología , Sistema Límbico/crecimiento & desarrollo , Sistema Límbico/ultraestructura , Datos de Secuencia Molecular , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/genética , Vías Nerviosas , Sistemas de Lectura Abierta , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes de Fusión/metabolismo , Transfección

RESUMEN

The limbic system-associated membrane protein (LAMP) is a 64-68 x 10(3) M(r) glycoprotein that is expressed by subsets of neurons that are functionally interconnected. LAMP exhibits characteristics that are indicative of a developmentally significant protein, such as an early and restricted pattern of expression and the ability to mediate specific fiber-target interactions. A potential, selective adhesive mechanism by which LAMP may regulate the formation of specific circuits is investigated in the present experiments. LAMP is readily released from intact membranes by phosphatidyl inositol-specific phospholipase C. Purified, native LAMP, isolated by PI-PLC digestion and immunoaffinity chromatography, is capable of mediating fluorescent Covasphere aggregation via homophilic binding. To test the ability of LAMP to selectively facilitate substrate adhesion and growth of neurons from LAMP-positive, in contrast to LAMP-negative regions of the developing brain, purified LAMP was dotted onto nitrocellulose-coated dishes and test cells plated. Limbic neurons from perirhinal cortex bind specifically to substrate-bound LAMP within 4 hours, forming small cell aggregates with short neuritic processes that continue to grow through a 48 hour period of monitoring. Preincubation of cells with anti-LAMP has a modest effect on cell binding but significantly reduces initiation of process growth. Non-limbic neurons from somatosensory cortex and olfactory bulb fail to bind or extend processes on the LAMP substrate to any significant extent. All cell populations bind equally well and form neurites on poly-D-lysine and laminin. The present results provide direct evidence that LAMP can specifically facilitate interactions with select neurons in the CNS during development. The data support the concept that patterned expression of unique cell adhesion molecules in functionally related regions of the mammalian brain can regulate circuit formation.

Asunto(s)

Sistema Límbico/embriología , Glicoproteínas de Membrana/farmacología , Neuronas/efectos de los fármacos , Animales , Western Blotting , Adhesión Celular/efectos de los fármacos , Células Cultivadas , Cromatografía de Afinidad , Sistema Límbico/citología , Glicoproteínas de Membrana/aislamiento & purificación , Neuronas/citología , Fosfatidilinositol Diacilglicerol-Liasa , Fosfoinositido Fosfolipasa C , Hidrolasas Diéster Fosfóricas , Ratas , Ratas Sprague-Dawley

RESUMEN

In bovine brain cortex cytoplasm we have identified a soluble protein (L-protein) of M(r) approximately 90 kDa interacting with polyclonal antibodies to alpha-latrotoxin. The L-protein forms potential-dependent and cation-selective ion channels in BLM, which are blocked by Cd2+. The fusogenic activity of the L-protein was demonstrated on liposomes. We have arrived at the conclusion that the action mechanisms of the L-protein and alpha-latrotoxin are similar.

Asunto(s)

Corteza Cerebral/química , Proteínas del Tejido Nervioso/química , Venenos de Araña/química , Animales , Bovinos , Membrana Dobles de Lípidos/química , Liposomas/química , Potenciales de la Membrana , Peso Molecular , Proteínas del Tejido Nervioso/aislamiento & purificación , Solubilidad

RESUMEN

Phosphorylation of the reconstructed TTX-sensitive cytosolic protein of the bovine brain has been studied. Some properties of the protein are similar to those of the membrane potential-dependent sodium channel. It is shown that the influence of phosphorylation by protein kinase A on the reconstructed channel greatly depends on the mode of reconstruction. Phosphorylation fo reconstructed channels in the open state leads to their closing. Preliminary phosphorylation of channel-forming protein results in a considerable increase of the activation effect of veratrine and scorpion toxin.

Asunto(s)

Membranas Artificiales , Proteínas Quinasas/metabolismo , Canales de Sodio/fisiología , Animales , Bovinos , Potenciales de la Membrana/fisiología , Proteínas del Tejido Nervioso/metabolismo , Fosforilación , Venenos de Escorpión/farmacología , Canales de Sodio/efectos de los fármacos , Tetrodotoxina/farmacología , Veratrina/farmacología

RESUMEN

Biochemical events leading to the formation of mature membrane-associated sodium channel proteins are not completely understood. We have recently purified a protein from the cytoplasm of brain cells, which is able to become incorporated into liposomes and induce neurotoxin-dependent sodium permeability. Here we report data on a monoclonal antibody derived against this protein. This antibody crossreacts with cell membrane preparations. The antibody binding to viable neuroblastoma cells is inhibited by veratrine, indicating that membrane molecules antigenically related to the cytoplasmic protein may also be related to the voltage-gated sodium channel.

Asunto(s)

Anticuerpos Monoclonales , Encéfalo/metabolismo , Activación del Canal Iónico , Proteínas del Tejido Nervioso/fisiología , Canales de Sodio/fisiología , Tetrodotoxina/farmacología , Animales , Anticuerpos Monoclonales/inmunología , Citoplasma/metabolismo , Resistencia a Medicamentos , Electrofisiología , Femenino , Inmunización , Ratones , Ratones Endogámicos BALB C , Proteínas del Tejido Nervioso/inmunología , Neurotoxinas/farmacología , Células Tumorales Cultivadas , Veratrina/farmacología

Asunto(s)

Proteínas Portadoras/metabolismo , Canales de Sodio/metabolismo , Tetrodotoxina/metabolismo , Veratrina/farmacología , Animales , Transporte Biológico , Anguilas , Liposomas/metabolismo , Sodio/metabolismo , Canales de Sodio/efectos de los fármacos , Solubilidad , Tetrodotoxina/farmacología

Asunto(s)

Encéfalo/metabolismo , Canales Iónicos/metabolismo , Canales de Sodio , Tetrodotoxina/metabolismo , Animales , Proteínas Portadoras/metabolismo , Bovinos , Cromatografía de Afinidad , Electroforesis en Gel de Poliacrilamida , Sueros Inmunes , Liposomas/metabolismo , Proteínas de la Membrana/aislamiento & purificación , Conejos

RESUMEN

Reconstruction of membrane proteins obtained from the Sepharose-rabbit immunoglobulins to bovine brain TTX-sensitive cytoplasmic protein column has been studied. The detergent method for studying potential-dependent sodium channel has been used in our modification. The results obtained indicate that cytoplasmic TTX-sensitive proteins are close to those of the membrane sodium channel.

Asunto(s)

Proteínas Portadoras/inmunología , Proteínas de la Membrana/inmunología , Neuronas/fisiología , Animales , Encéfalo/metabolismo , Proteínas Portadoras/aislamiento & purificación , Bovinos , Electroforesis en Gel de Poliacrilamida , Canales Iónicos , Proteínas de la Membrana/aislamiento & purificación , Sodio/metabolismo , Canales de Sodio/fisiología

RESUMEN

Hypothetical antigenic similarities between nerve cell membrane structures and cytoplasmic tetrodotoxin-sensitive proteins have been studied. Indirect ELISA binding assay combined with inhibition assay has been used. The results obtained indicate that cytoplasmic tetrodotoxin-sensitive proteins do share antigenic determinants with nerve cell membrane structures. This is consistent with the speculation that cytoplasmic tetrodotoxin-sensitive proteins are relatives of membrane sodium channels.

Asunto(s)

Epítopos/análisis , Proteínas de la Membrana/inmunología , Proteínas del Tejido Nervioso/inmunología , Neuronas/inmunología , Tetrodotoxina/farmacología , Animales , Encéfalo/inmunología , Bovinos , Línea Celular , Membrana Celular/inmunología , Citoplasma/inmunología , Ratones , Neuroblastoma , Ratas , Sinaptosomas/inmunología

RESUMEN

Highly purified protein inducing tetrodotoxin-dependent Na fluxes in liposomal membrane was obtained from the cytoplasmic fraction of the bovine brain. The protein was purified by anion-exchange chromatography on DEAE-Servacell and wheat germ agglutinin sepharose (WGA) followed by gel filtration on sepharose 4B. It is a high-molecular weight acidic glycoprotein; during denaturation under reducing conditions it forms 55 kD subunits. It is suggested that the tetrodotoxin-sensitive protein could be a soluble intracellular precursor of the voltage-dependent sodium channels.

Asunto(s)

Química Encefálica , Glicoproteínas/aislamiento & purificación , Canales Iónicos/análisis , Proteínas del Tejido Nervioso/aislamiento & purificación , Sodio/metabolismo , Tetrodotoxina/farmacología , Animales , Encéfalo/efectos de los fármacos , Bovinos , Fenómenos Químicos , Química , Canales Iónicos/efectos de los fármacos