RESUMEN
No disponible
Asunto(s)
Humanos , Femenino , Persona de Mediana Edad , Queratoacantoma/cirugía , Queratoacantoma/patología , Queratoacantoma , Examen Físico/instrumentación , Examen Físico/métodos , Examen Físico , Diagnóstico Precoz , Ultrasonografía Doppler/instrumentación , Ultrasonografía Doppler/métodos , Ultrasonografía Doppler , Carcinoma/clasificación , Carcinoma/complicaciones , Carcinoma/diagnóstico , Declaración de HelsinkiRESUMEN
The NLR pyrin domain containing 3 (NLRP3) inflammasome is a major component of the innate immune system, but its mechanism of activation by a wide range of molecules remains largely unknown. Widely used nano-sized inorganic metal oxides such as silica dioxide (nano-SiO2) and titanium dioxide (nano-TiO2) activate the NLRP3 inflammasome in macrophages similarly to silica or asbestos micro-sized particles. By investigating towards the molecular mechanisms of inflammasome activation in response to nanoparticles, we show here that active adenosine triphosphate (ATP) release and subsequent ATP, adenosine diphosphate (ADP) and adenosine receptor signalling are required for inflammasome activation. Nano-SiO2 or nano-TiO2 caused a significant increase in P2Y1, P2Y2, A2A and/or A2B receptor expression, whereas the P2X7 receptor was downregulated. Interestingly, IL-1ß secretion in response to nanoparticles is increased by enhanced ATP and ADP hydrolysis, whereas it is decreased by adenosine degradation or selective A2A or A2B receptor inhibition. Downstream of these receptors, our results show that nanoparticles activate the NLRP3 inflammasome via activation of PLC-InsP3 and/or inhibition of adenylate cyclase (ADCY)-cAMP pathways. Finally, a high dose of adenosine triggers inflammasome activation and IL-1ß secretion through adenosine cellular uptake by nucleotide transporters and by its subsequent transformation in ATP by adenosine kinase. In summary, we show for the first time that extracellular adenosine activates the NLRP3 inflammasome by two ways: by interacting with adenosine receptors at nanomolar/micromolar concentrations and through cellular uptake by equilibrative nucleoside transporters at millimolar concentrations. These findings provide new molecular insights on the mechanisms of NLRP3 inflammasome activation and new therapeutic strategies to control inflammation.
Asunto(s)
Adenosina Difosfato/farmacología , Adenosina Trifosfato/farmacología , Adenosina/farmacología , Proteínas Portadoras/metabolismo , Inflamasomas/metabolismo , Nanopartículas/química , Adenilil Ciclasas/metabolismo , Animales , Línea Celular , Conexinas/metabolismo , AMP Cíclico/metabolismo , Humanos , Fosfatos de Inositol/metabolismo , Interleucina-1beta/metabolismo , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Ratones Endogámicos C57BL , Modelos Biológicos , Proteína con Dominio Pirina 3 de la Familia NLR , Proteínas del Tejido Nervioso/metabolismo , Neumonía/patología , Receptores Purinérgicos P1/metabolismo , Receptores Purinérgicos P2Y/metabolismo , Transducción de Señal/efectos de los fármacos , Dióxido de Silicio/farmacología , Titanio/farmacología , Fosfolipasas de Tipo C/metabolismoRESUMEN
Deposition of uric acid crystals in joints causes the acute and chronic inflammatory disease known as gout and prolonged airway exposure to silica crystals leads to the development of silicosis, an irreversible fibrotic pulmonary disease. Aluminum salt (Alum) crystals are frequently used as vaccine adjuvant. The mechanisms by which crystals activate innate immunity through the Nlrp3 inflammasome are not well understood. Here, we show that uric acid, silica and Alum crystals trigger the extracellular delivery of endogenous ATP, which just precedes the secretion of mature interleukin-1ß (IL-1ß) by macrophages, both events depending on purinergic receptors and connexin/pannexin channels. Interestingly, not only ATP but also ADP and UTP are involved in IL-1ß production upon these Nlrp3 inflammasome activators through multiple purinergic receptor signaling. These findings support a pivotal role for nucleotides as danger signals and provide a new molecular mechanism to explain how chemically and structurally diverse stimuli can activate the Nlrp3 inflammasome.
Asunto(s)
Adenosina Trifosfato/metabolismo , Inflamasomas/metabolismo , Receptores Purinérgicos/metabolismo , Adenosina Difosfato/metabolismo , Aluminio/química , Aluminio/farmacología , Animales , Proteínas Portadoras/metabolismo , Células Cultivadas , Conexinas/metabolismo , Proteasas de Cisteína/metabolismo , Humanos , Inmunidad Innata , Inflamasomas/efectos de los fármacos , Interleucina-1beta/metabolismo , Macrófagos/citología , Macrófagos/metabolismo , Ratones , Proteína con Dominio Pirina 3 de la Familia NLR , Receptores Purinérgicos/genética , Transducción de Señal/efectos de los fármacos , Dióxido de Silicio/química , Dióxido de Silicio/farmacología , Ácido Úrico/química , Ácido Úrico/farmacología , Uridina Trifosfato/metabolismoRESUMEN
BACKGROUND: Pseudoxanthoma elasticum (PXE) is related to mutations in the ABCC6 gene and characterized pathologically by dystrophic and mineralized elastic fibres. Heterozygote carriers of ABCC6 mutations may have a limited PXE phenotype. OBJECTIVE: To compare histological changes in the skin of genotyped siblings from two PXE pedigrees. METHODS: Mutation analysis of ABCC6 was performed. Skin biopsy samples were stained (orcein) and immunolabelled for elastin, and for vitronectin and bone sialoprotein, which are partially responsible for the mineralization within the elastorrhexic fibres. Results In all individuals mutation analysis of ABCC6 allowed definition of the genotype status, i.e. PXE (n = 2), heterozygote (n = 7) or wild type (n = 2). The study identified three histological phenotypes related to the ABCC6 genotype in siblings from both families. Heterozygote carriers had changes in dermal elastic fibre organization, morphology and labelling midway between those seen in PXE skin and normal skin. CONCLUSION: Even though the number of individuals studied here is small and precludes any hasty generalization, having a single mutation in the ABCC6 gene seems enough to modify dermal elastic fibres. The relevance of performing a skin biopsy to identify heterozygote carriers in the family of a PXE patient remains to be determined.
Asunto(s)
Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Seudoxantoma Elástico/genética , Seudoxantoma Elástico/patología , Alelos , Exones , Femenino , Heterocigoto , Humanos , Técnicas para Inmunoenzimas , Mutación Missense , Linaje , FenotipoRESUMEN
BACKGROUND: Pseudoxanthoma elasticum (PXE) is normally associated with mutations in the ABCC6 gene. A PXE phenotype without mutations in ABCC6 has been described in Greek and Italian patients presenting with beta thalassemia. We attempted to determine the incidence of beta thalassemia in a cohort of French patients with PXE. PATIENTS AND METHODS: Fifty patients with PXE were included in the study. Laboratory examinations comprised hemoglobin electrophoresis, ABCC6 gene study and in some studies: mutation analysis, beta-globin gene. RESULTS: No cases of beta thalassemia were diagnosed in this cohort of French patients with PXE. However, 20% of the latter exhibited a significant but isolated (i.e. without microcytic anemia) increase of hemoglobin A2 (HbA2). Statistical comparisons showed no difference in terms of geographical origin or severity of PXE between patients with high levels of HbA2 and those with normal levels of HbA2 other than the extent of cutaneous involvement. Study of the beta-globin gene displayed mutations only in the two patients with the highest recorded levels of HbA2. ABCC6 + beta-globin digenism was ruled out of the pathogenesis of PXE. DISCUSSION: The PXE phenotype seen in some patients with beta thalassemia appears to be associated with epigenetic modification of ABCC6 transcription and depends specifically on the beta globin locus. Isolated increase in HbA2 is probably a laboratory marker for PXE. Here again, a functional epigenetic reaction between ABCC6 and the beta-globin locus was suspected. However, these reciprocal interactions are clearly unequal since the change in ABCC6 transcription occurring during the course of beta thalassaemia is responsible for a PXE phenotype while increased HbA2 during the course of PXE has no clinical consequences.
Asunto(s)
Hemoglobina A2/análisis , Seudoxantoma Elástico/sangre , Adolescente , Adulto , Anciano , Estudios de Cohortes , Epigénesis Genética/genética , Volumen de Eritrocitos , Femenino , Globinas/análisis , Globinas/genética , Humanos , Masculino , Persona de Mediana Edad , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/análisis , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Mutación/genética , Fenotipo , Seudoxantoma Elástico/clasificación , Seudoxantoma Elástico/genética , Transcripción Genética/genética , Talasemia beta/sangreRESUMEN
Pseudoxanthoma elasticum (PXE) is an inherited systemic disease of connective tissue primarily affecting the skin, retina, and cardiovascular system. It is characterised pathologically by elastic fibre mineralisation and fragmentation (so called "elastorrhexia"), and clinically by high heterogeneity in age of onset and the extent and severity of organ system involvement. PXE was recently associated with mutations in the ABCC6 (ATP binding cassette subtype C number 6) gene. At least one ABCC6 mutation is found in about 80% of patients. These mutations are identifiable in most of the 31 ABCC6 exons and consist of missense, nonsense, frameshift mutations, or large deletions. No correlation between the nature or location of the mutations and phenotype severity has yet been established. Recent findings support exclusive recessive inheritance. The proposed prevalence of PXE is 1/25,000, but this is probably an underestimate. ABCC6 encodes the protein ABCC6 (also known as MRP6), a member of the large ATP dependent transmembrane transporter family that is expressed predominantly in the liver and kidneys, and only to a lesser extent in tissues affected by PXE. The physiological substrates of ABCC6 remain to be determined, but the current hypothesis is that PXE should be considered to be a metabolic disease with undetermined circulating molecules interacting with the synthesis, turnover, or maintenance of elastic fibres.
Asunto(s)
Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Mutación , Seudoxantoma Elástico/genética , Seudoxantoma Elástico/patología , Adenosina Trifosfato/química , Adenosina Trifosfato/metabolismo , Codón sin Sentido , Exones , Matriz Extracelular/metabolismo , Mutación del Sistema de Lectura , Eliminación de Gen , Humanos , Modelos Genéticos , Mutación Missense , Fenotipo , Seudoxantoma Elástico/diagnóstico , Piel/patologíaRESUMEN
Mouse embryonic stem (ES) cells are an important tool for generation of transgenic mice and genetically modified mice. A rapid and efficient separation of ES cells that respects cell integrity, viability, and their developmental potential while also allowing purified ES fraction collection under sterile conditions might be of great interest to facilitate the generation of chimeric animals. In this study, we demonstrated for the first time the effectiveness of a sedimentation field-flow fractionation (SdFFF) cell sorter to provide, with a characteristic DNA content, a purified ES cell fraction and with a high in vivo developmental potential to prepare transgenic mice by generation of chimeras having a high percentage of chimerism.
Asunto(s)
Separación Celular/métodos , Quimera/genética , Embrión de Mamíferos/citología , Fraccionamiento de Campo-Flujo , Ratones Transgénicos , Células Madre/fisiología , Animales , Quimera/fisiología , ADN/genética , Transferencia de Embrión , RatonesRESUMEN
Four transcriptional enhancers lie downstream of the immunoglobulin heavy chain locus: Calpha3'/hs3a, hs1,2, hs3b, and hs4. Although individually weak, these elements have strong transcriptional synergies when combined and they altogether behave as a locus control region. Previous knockout experiments in the 3' region have shown that both hs3a and hs1,2 are dispensable for normal expression and rearrangement of the IgH locus but that their replacement with a transcribed neo gene severely affects class switch recombination. Here we show that even in the absence of a neo gene, joint deletion of the last two 3' enhancers, hs3b and hs4, severely impairs germline transcription and class switching to most isotypes and may in addition affect mu gene expression in resting B cells.
Asunto(s)
Cambio de Clase de Inmunoglobulina/genética , Cadenas Pesadas de Inmunoglobulina/genética , Región de Control de Posición/genética , Recombinación Genética , Animales , Linfocitos B , Elementos de Facilitación Genéticos , Heterocigoto , Homocigoto , Isotipos de Inmunoglobulinas/biosíntesis , Inmunoglobulina M/biosíntesis , Cadenas mu de Inmunoglobulina/genética , Tejido Linfoide , Ratones , Ratones Transgénicos , ARN Mensajero/biosíntesis , Eliminación de Secuencia , Bazo/inmunologíaRESUMEN
BACKGROUND: Transplantation of fetal cardiomyocytes has been shown to improve function of regionally infarcted myocardium, but its effects on global heart failure are still unknown. METHODS AND RESULTS: Heart failure was induced in female mice by intraperitoneal injection of doxorubicin (2 mg/kg twice per week over 2 cycles of 2 weeks separated by a 2-week drug-free period). One week after the end of treatment, left ventricular function was assessed by transthoracic echocardiography (baseline). Animals were then randomized into 3 groups: The treated group (n = 12) received an intramyocardial injection of fetal cardiomyocytes (1 x 10(6) in 10 microL) harvested from transgenic mice expressing the gene of beta-galactosidase, the control group (n = 15) received an equivalent volume of culture medium alone, and 10 sham mice had no surgery. Two weeks and 1 month after transplantation, function was again assessed echocardiographically. At baseline, fractional shortening was not significantly different between the 3 groups. It then significantly increased in cell-treated mice at 2 weeks and 1 month after transplantation (P < 0.002 and P < 0.03 versus baseline, respectively), whereas it did not change in untreated animals. Transplanted cells could not be identified by beta-galactosidase activity or presence of Y chromosome (with 1 exception). CONCLUSIONS: Cellular transplantation can improve function of globally failing hearts by a mechanism that might not necessarily involve the sustained presence of transplanted cells but rather the effects of cardioprotective factors released by them.
Asunto(s)
Gasto Cardíaco Bajo/inducido químicamente , Gasto Cardíaco Bajo/cirugía , Trasplante de Células , Doxorrubicina , Trasplante de Tejido Fetal , Miocardio/citología , Animales , Gasto Cardíaco Bajo/diagnóstico por imagen , Ecocardiografía , Femenino , Corazón/embriología , Ratones , Factores de TiempoRESUMEN
pp125 focal adhesion kinase (FAK), a cytoplasmic tyrosine kinase transducing signals initiated by integrin engagement and G protein-coupled receptors, is highly expressed in brain. FAK from brain had a higher molecular weight and an increased autophosphorylation activity, than from other tissues. In addition to a 9-base insertion in the 3'-coding region, which defines FAK+, rat striatal FAK mRNAs contained several additional short exons, coding for peptides of 28, 6, and 7 residues, respectively (termed boxes 28, 6, and 7), surrounding the autophosphorylated Tyr-397. In transfected COS 7 cells, the presence of boxes 6 and 7 conferred an increased overall tyrosine phosphorylation, a higher phosphorylation of Tyr-397 assessed with a phosphorylation state-specific antibody, and a more active autophosphorylation in immune precipitates. The presence of box 28 did not alter further these parameters. Two-dimensional phosphopeptide maps of hippocampal FAK were identical to those of FAK+6,7. The presence of the various exons did not alter the interaction of FAK with c-Src, n-Src, or Fyn. Thus, several splice isoforms of FAK are preferentially expressed in rat brain, some of which have an increased autophosphorylation activity, suggesting that FAK may have specific properties in neurons.
Asunto(s)
Empalme Alternativo , Encéfalo/enzimología , Moléculas de Adhesión Celular/genética , Proteínas Tirosina Quinasas/genética , Receptor de Insulina/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Células COS , Moléculas de Adhesión Celular/metabolismo , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Isoenzimas/genética , Isoenzimas/metabolismo , Ratones , Datos de Secuencia Molecular , Mapeo Peptídico , Fosforilación , Proteínas Tirosina Quinasas/metabolismo , ARN Mensajero/metabolismo , Ratas , Receptor de Insulina/metabolismoRESUMEN
Ranvier nodes are flanked by paranodal regions, at the level of which oligodendrocytes or Schwann cells interact closely with axons. Paranodes play a critical role in the physiological properties of myelinated nerve fibers. Paranodin, a prominent 180 kDa transmembrane neuronal glycoprotein, was purified and cloned from adult rat brain, and found to be highly concentrated in axonal membranes at their junction with myelinating glial cells, in paranodes of central and peripheral nerve fibers. The large extracellular domain of paranodin is related to neurexins, and its short intracellular tail binds protein 4.1, a cytoskeleton-anchoring protein. Paranodin may be a critical component of the macromolecular complex involved in the tight interactions between axons and myelinating glial cells characteristic of the paranodal region.
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Encéfalo/metabolismo , Glicoproteínas/metabolismo , Glicoproteínas de Membrana/fisiología , Neuronas/metabolismo , Neuropéptidos/fisiología , Secuencia de Aminoácidos , Animales , Clonación Molecular , Hibridación in Situ , Datos de Secuencia Molecular , Conejos , Nódulos de Ranvier/metabolismo , RatasRESUMEN
Anandamide is an endogenous ligand for central cannabinoid receptors and is released after neuronal depolarization. Anandamide increased protein tyrosine phosphorylation in rat hippocampal slices and neurons in culture. The action of anandamide resulted from the inhibition of adenylyl cyclase and cyclic adenosine 3', 5'-monophosphate-dependent protein kinase. One of the proteins phosphorylated in response to anandamide was an isoform of pp125-focal adhesion kinase (FAK+) expressed preferentially in neurons. Focal adhesion kinase is a tyrosine kinase involved in the interactions between the integrins and actin-based cytoskeleton. Thus, anandamide may exert neurotrophic effects and play a role in synaptic plasticity.
Asunto(s)
Ácidos Araquidónicos/farmacología , Moléculas de Adhesión Celular/metabolismo , Hipocampo/enzimología , Neuronas/enzimología , Proteínas Tirosina Quinasas/metabolismo , Inhibidores de Adenilato Ciclasa , Adenilil Ciclasas/metabolismo , Secuencia de Aminoácidos , Animales , Ácido Araquidónico/farmacología , Línea Celular , Células Cultivadas , AMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/antagonistas & inhibidores , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Endocannabinoides , Quinasa 1 de Adhesión Focal , Proteína-Tirosina Quinasas de Adhesión Focal , Hipocampo/efectos de los fármacos , Técnicas In Vitro , Datos de Secuencia Molecular , Plasticidad Neuronal/efectos de los fármacos , Neuronas/efectos de los fármacos , Fosforilación , Fosfotirosina/metabolismo , Alcamidas Poliinsaturadas , Prosencéfalo , Ratas , Receptores de Cannabinoides , Receptores de Droga/metabolismoRESUMEN
It has been shown previously that acidic K18 and K19 keratins display a differential immunohistochemical pattern of expression during sexual differentiation of the gonads in the rat (Fridmacher et al. (1992) Development 115, 503-517). The present results indicate that K18 and K19 gene expression is regulated at the transcriptional level. The analysis was performed by Northern Blot, reverse transcriptase polymerase chain reaction (RT-PCR) and in situ hybridization. PCR products were cloned, sequenced and used as species-specific K18 and K19 riboprobes for in situ hybridization. K19 mRNA but not K18 mRNA was detected in undifferentiated gonads and in somatic cells of ovarian cords throughout the fetal ovary development. K18 mRNA expression appeared in male gonads, at 13.5 days of gestation, at the onset of testicular differentiation, as the first Sertoli cells differentiated and aggregated to form seminiferous cords. As testicular differentiation progressed, K19 mRNA disappeared and, from 14.5 days of gestation on, fetal Sertoli cells expressed exclusively K18 mRNA. The changes in the transcriptional activity of K19 and K18 genes, observed in male gonads, occur characteristically at the very beginning of testicular differentiation. In the male pathway of sexual differentiation, the switch in K19/K18 gene expression is, in addition to the activation of the anti-Müllerian hormone gene, the most precocious regulative event occurring after the expression of the testis determining factor SRY.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica/fisiología , Queratinas/genética , Diferenciación Sexual/genética , Testículo/embriología , Animales , Secuencia de Bases , Femenino , Edad Gestacional , Masculino , Datos de Secuencia Molecular , Ovario/embriología , ARN Mensajero/biosíntesis , Ratas , Ratas WistarRESUMEN
Different types of glial precursor cell lines were obtained after stable transfection of brain cells with the pJC-SVLTtsA vector carrying the tsA58 simian virus 40 large T (SVLT) gene driven by the promoter of a gliotropic strain of JC papovavirus. The immortalized cells were conditional for growth: they expressed the SVLT antigen and proliferated at 34 degrees C, but their growth was either reduced or arrested when they were shifted to 39 degrees C. The differentiation characteristics of four representative lines were more extensively studied. The CR15 and CM8 lines displayed properties of bipotential glial progenitors: they were able to express oligodendrocyte markers at both temperatures, but could differentiate into astrocytes only at 39 degrees C. In contrast, the CR19 and CM3r lines corresponded to more committed oligodendrocyte precursors: they expressed various oligodendroglial markers but they could not synthesize the glial fibrillary acidic protein. More particularly, the CM3r mouse cells displayed a typical oligodendrocyte progenitor morphology and expressed the proteolipid protein mRNA.
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Antígenos Virales de Tumores/genética , Encéfalo/citología , Neuroglía/citología , Oncogenes , Células Madre/citología , Animales , Secuencia de Bases , Diferenciación Celular , Línea Celular , Regulación de la Expresión Génica , Virus JC/genética , Ratones , Mitosis/fisiología , Datos de Secuencia Molecular , Proteínas del Tejido Nervioso/biosíntesis , Neuroglía/fisiología , Regiones Promotoras Genéticas/genética , Ratas , Ratas Sprague-Dawley , Virus 40 de los Simios/genética , Células Madre/fisiología , Transformación GenéticaRESUMEN
In rats poisoned with soman, an irreversible organophosphate anticholinesterase, acute changes in blood-brain barrier (BBB) permeability to proteins were investigated, using Evans Blue (EB)-labelled serum albumin and plasmatic gamma-immunoglobulin G (IgG) as indicators. Confirming previously published data, soman produced a conspicuous seizure-related and reversible BBB opening which was greatest after 30 to 60 min of paroxysmal electroencephalographic (EEG) discharges when signs of cerebral hyperactivity (epileptic EEG pattern, hyperoxia) were also at their height. Topographically, the protein leakage was bilateral and restricted to anatomically defined brain structures, some of which being thereafter sites of parenchymal edema and neuronal damage. In these areas (e.g., the thalamus), the edema is probably, at least in part, "vasogenic" in origin, and the possible contribution of the transient BBB opening to the neuronal lesions was questioned. On the other hand, the hippocampus, a region preferentially affected by the soman-induced acute neuropathology, was always free of any protein leakage, suggesting that the edema is unrelated to vascular damage and "cytotoxic" in nature. Finally, no topographic relationship was shown to exist between the increase in cerebrovascular permeability produced by soman and the histochemically-detected inhibition of the parenchymal total cholinesterases (ChE) or endothelial butyrylcholinesterase (BuChE).
Asunto(s)
Barrera Hematoencefálica/efectos de los fármacos , Convulsiones/inducido químicamente , Soman/envenenamiento , Animales , Proteínas Sanguíneas/metabolismo , Encéfalo/efectos de los fármacos , Encéfalo/enzimología , Inhibidores de la Colinesterasa/envenenamiento , Colinesterasas/metabolismo , Electroencefalografía/efectos de los fármacos , Masculino , Microscopía Fluorescente , Oxígeno/metabolismo , Presión Parcial , Ratas , Ratas Endogámicas , Convulsiones/fisiopatologíaRESUMEN
The microvessels of the rat subfornical organ (SFO) are heterogeneous: those of the caudal part lack a blood-brain barrier (BBB) unlike those of the rostral part. The astroglial environment of these microvessels has been studied by combining an immunocytochemical technique employing an anti-GFAP (glial fibrillary acidic protein) antiserum with the morphological detection of a barrier to the protein-silver complex. All the SFO microvessels are surrounded by astrocytes characterized by a tumescent aspect; however, the relative proximity between the astrocytic feet and the endothelial cells varies considerably. The capillaries provided with a barrier (rostral SFO) are contiguous with the astrocytes from which they are only separated by a basement membrane. The capillaries devoid of BBB (caudal SFO) are surrounded by a pericapillary space that keeps the astrocytes at a short distance (capillaries with a very rich vesicular endothelium) or at a long distance (capillaries with a fenestrated endothelium). The astrocytes are absent in the choroid plexus where all microvessels are fenestrated and lack a barrier. These data suggest that the astrocytes release one or more signals which in their vicinity inhibit the expression of endothelial morphological characteristics (fenestrations, vesicles) responsible for the leakage of plasmatic proteins from the blood to the cerebral parenchyma of the circumventricular organs.
Asunto(s)
Astrocitos/fisiología , Barrera Hematoencefálica/fisiología , Endotelio Vascular/fisiología , Sistemas Neurosecretores/irrigación sanguínea , Órgano Subfornical/irrigación sanguínea , Animales , Astrocitos/ultraestructura , Endotelio Vascular/ultraestructura , Femenino , Proteína Ácida Fibrilar de la Glía/análisis , Técnicas para Inmunoenzimas , Masculino , Permeabilidad , Ratas , Ratas Endogámicas , Nitrato de Plata , Órgano Subfornical/ultraestructuraRESUMEN
The effect of the neurotrophic factor NGF on the expression of two genes involved in the accumulation of amyloid deposits in neurodegenerative disorders was studied in a clonal cell line, PC12. Use of hybridization methods showed that NGF increased the cellular pool of the mRNA of the prion protein, a macromolecule known to generate fibrillary aggregates in the brain of scrapie-infected animals. Maximal levels of prion mRNA were obtained after 7 days of treatment, but a significant increase was already detectable after 48 hr of exposure to NGF. In contrast, the factor did not increase the cellular content of the transcripts coding for the precursor of the beta-amyloid peptide (APP), which participates in the formation of neuritic plaques in human brains affected by Alzheimer's disease. However, NGF caused a drop in the molecular weight of that mRNA. This change, which is likely to result from a loss of 100-200 bp, was already detected after 24 hr of treatment. These results indicate that NGF induces in target neuronal cells a quantitative and a qualitative modification of the transcription products encoding two different amyloid precursor proteins.