RESUMEN
Transmissible subacute spongiform encephalopathies (TSE) are animal and human neurodegenerative diseases. The nature of the transmissible agent remains unknown. The specific molecular marker of these diseases is the abnormal isoform of the prion protein (PrP). This protein is encoded by a cellular gene and accumulates in a pathological isoform (PrPres) which is partially resistant to proteolysis. The tridimensional structure of this protein remains theoretical. F. Cohen proposed one of the most realistic models. According to this model and from molecular mechanics calculation, we suggest a PrP oligomeric ionic channel model that may be involved in TSE-induced neuronal apoptosis.
Asunto(s)
Canales Iónicos/fisiología , Modelos Biológicos , Neuronas/patología , Enfermedades por Prión/fisiopatología , Priones/patogenicidad , Animales , Apoptosis/fisiología , Humanos , Enfermedades por Prión/patología , Priones/fisiología , Conformación ProteicaRESUMEN
The expression of the mRNA of nine scrapie responsive genes was analyzed in the brains of FVB/N mice infected with bovine spongiform encephalopathy (BSE). The RNA transcripts of eight genes were overexpressed to a comparable extent in both BSE-infected and scrapie-infected mice, indicating a common series of pathogenic events in the two transmissible spongiform encephalopathies (TSEs). In contrast, the serine proteinase inhibitor spi 2, an analogue of the human alpha-1 antichymotrypsin gene, was overexpressed to a greater extent in the brains of scrapie-infected animals than in animals infected with BSE, reflecting either an agent specific or a mouse strain specific response. The levels of spi 2 mRNA were increased during the course of scrapie prior to the onset of clinical signs of the disease and the increase reached 11 to 45 fold relative to uninfected controls in terminally ill mice. Spi 2, in common with four of the other scrapie responsive genes studied, is known to be associated with pro-inflammatory processes. These observations underline the importance of cell reactivity in TSE. In addition, scrg2 mRNA the level of which is enhanced in TSE-infected mouse brain, was identified as a previously unrecognized long transcript of the murine aldolase C gene. However, the level of the principal aldolase C mRNA is unaffected in TSE. The increased representation of the longer transcript in the late stage of the disease may reflect changes in mRNA processing and/or stability in reactive astrocytes or in damaged Purkinje cells.
Asunto(s)
Encéfalo/metabolismo , Encefalopatía Espongiforme Bovina/metabolismo , ARN Mensajero/metabolismo , Scrapie/genética , Animales , Secuencia de Bases , Complemento C1q/genética , Complemento C1q/metabolismo , Encefalopatía Espongiforme Bovina/enzimología , Fructosa-Bifosfato Aldolasa/genética , Fructosa-Bifosfato Aldolasa/metabolismo , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Scrapie/enzimología , Scrapie/metabolismo , Inhibidores de Serina Proteinasa/genética , Inhibidores de Serina Proteinasa/metabolismoRESUMEN
Spongiform transmissible encephalopathies are neurodegenerative diseases characterized by the accumulation, in infected brains, of a pathological form of a normal host-encoded protein called PrP. Previous data have shown that PrP could interact with cytosolic factors, including nuclear molecules, emphasizing the possible function of such interactions. Moreover, in infected cells, PrP is observed not only at the plasma membrane but also in the nuclear compartment. The N-terminal extremity of the mature PrP has been thought to harbor a nuclear localization signal reminiscent of the nuclear localization signal of the simian virus 40 large T antigen. By designing a fusion protein between the putative nuclear localization signal of PrP and the green fluorescent protein, we have shown that the N-terminal sequence of PrP is not efficient in targeting the protein in the nuclear compartment. This implies new insights regarding the way by which PrP could, however, reach the nuclear compartment.
Asunto(s)
Núcleo Celular/química , Núcleo Celular/metabolismo , Señales de Localización Nuclear , Proteínas PrPC/química , Proteínas PrPC/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Transporte Biológico/fisiología , Proteínas Fluorescentes Verdes , Células HeLa , Humanos , Inmunohistoquímica , Indicadores y Reactivos , Proteínas Luminiscentes , Microscopía Confocal , Datos de Secuencia Molecular , Plásmidos , Proteínas PrPC/genética , Análisis de Secuencia de ADN , TransfecciónRESUMEN
The agent responsible for transmissible spongiform encephalopathies (TSEs) is thought to be a malfolded, protease-resistant version (PrPres) of the normal cellular prion protein (PrP). The interspecies transmission of bovine spongiform encephalopathy (BSE) to mice was studied. Although all of the mice injected with homogenate from BSE-infected cattle brain exhibited neurological symptoms and neuronal death, more than 55 percent had no detectable PrPres. During serial passage, PrPres appeared after the agent became adapted to the new host. Thus, PrPres may be involved in species adaptation, but a further unidentified agent may actually transmit BSE.
Asunto(s)
Química Encefálica , Encefalopatía Espongiforme Bovina/transmisión , Proteínas del Tejido Nervioso/análisis , Priones/análisis , Animales , Apoptosis , Astrocitos/patología , Encéfalo/patología , Bovinos , Encefalopatía Espongiforme Bovina/metabolismo , Encefalopatía Espongiforme Bovina/patología , Endopeptidasas/metabolismo , Ratones , Ratones Endogámicos C57BL , Fenotipo , Células de Purkinje/patología , Pase Seriado , Factores de Tiempo , Vacuolas/patologíaAsunto(s)
Síndrome de Creutzfeldt-Jakob/genética , Hormona del Crecimiento/efectos adversos , Enfermedad Iatrogénica , Priones/genética , Síndrome de Creutzfeldt-Jakob/epidemiología , Síndrome de Creutzfeldt-Jakob/etiología , Francia/epidemiología , Tamización de Portadores Genéticos , Marcadores Genéticos , Humanos , Mutación Puntual , Polimorfismo GenéticoRESUMEN
The accumulation in brain of the 'prion protein' (PrP), a host-encoded sialoglycoprotein, is the unique specific molecular marker of subacute spongiform transmissible encephalopathies (SSTE). Furthermore, the primary sequence of the PrP gene (PRNP) seems to contain some genetic determinants of great importance in the development of SSTE. Here we present a simple and rapid polymerase chain reaction (PCR)-based method for direct sequencing of the entire coding sequence of the PrP gene, PRNP, in patients. The ability to determine sequences of both alleles of the PRNP gene is demonstrated in the analysis of 3 patients previously established as codon 129 heterozygotes by the use allele-specific oligonucleotide hybridization method.