RESUMEN
The protein MENIN is the product of the multiple endocrine neoplasia type I (MEN1) gene. Altered MENIN expression is one of the few events that are clearly associated with foregut neuroendocrine tumours (NETs), classical oncogenes or tumour suppressors being not involved. One of the current challenges is to understand how alteration of MENIN expression contributes to the development of these tumours. We hypothesised that MENIN might regulate factors maintaining endocrine-differentiated functions. We chose the insulinoma model, a paradigmatic example of well-differentiated pancreatic NETs, to study whether MENIN interferes with the expression of v-MAF musculoaponeurotic fibrosarcoma oncogene homologue A (MAFA), a master glucose-dependent transcription factor in differentiated ß-cells. Immunohistochemical analysis of a series of human insulinomas revealed a correlated decrease in both MENIN and MAFA. Decreased MAFA expression resulting from targeted Men1 ablation was also consistently observed in mouse insulinomas. In vitro analyses using insulinoma cell lines showed that MENIN regulated MAFA protein and mRNA levels, and bound to Mafa promoter sequences. MENIN knockdown concomitantly decreased mRNA expression of both Mafa and ß-cell differentiation markers (Ins1/2, Gck, Slc2a2 and Pdx1) and, in parallel, increased the proliferation rate of tumours as measured by bromodeoxyuridine incorporation. Interestingly, MAFA knockdown alone also increased proliferation rate but did not affect the expression of candidate proliferation genes regulated by MENIN. Finally, MENIN variants with missense mutations detected in patients with MEN1 lost the WT MENIN properties to regulate MAFA. Together, our findings unveil a previously unsuspected MENIN/MAFA connection regarding control of the ß-cell differentiation/proliferation balance, which could contribute to tumorigenesis.
Asunto(s)
Carcinoma Neuroendocrino/patología , Diferenciación Celular , Insulinoma/patología , Factores de Transcripción Maf de Gran Tamaño/metabolismo , Neoplasias Pancreáticas/patología , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas/fisiología , Adulto , Anciano , Animales , Apoptosis , Western Blotting , Carcinoma Neuroendocrino/genética , Carcinoma Neuroendocrino/metabolismo , Proliferación Celular , Inmunoprecipitación de Cromatina , Femenino , Glucosa/farmacología , Humanos , Técnicas para Inmunoenzimas , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patología , Insulinoma/genética , Insulinoma/metabolismo , Factores de Transcripción Maf de Gran Tamaño/antagonistas & inhibidores , Factores de Transcripción Maf de Gran Tamaño/genética , Masculino , Ratones , Ratones Noqueados , Persona de Mediana Edad , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/genética , ARN Mensajero/genética , ARN Interferente Pequeño/genética , Ratas , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células Tumorales CultivadasRESUMEN
Over a period of 17 years, 84 bacterial isolates identified as Mannheimia haemolytica or M. glucosida, and 52 isolates identified as Pasteurella trehalosi were detected in the lungs of domestic and wild ruminants in the French Alps. The isolates were serotyped according to their surface capsular antigens, and those sharing common antigens were further characterized by pulsed field gel electrophoresis. The results showed that the bacterial isolates included in the study clustered according to the host species from which they were isolated. These findings indicate that the transmission of serotypes of M. haemolytica, M. glucosida or P. trehalosi from an animal host in which they are common to another species sharing the same geographical space may be a rare epidemiological event.
Asunto(s)
Animales Domésticos/microbiología , Animales Salvajes/microbiología , Electroforesis en Gel de Campo Pulsado/veterinaria , Mannheimia haemolytica/clasificación , Pasteurella/clasificación , Animales , Electroforesis en Gel de Campo Pulsado/métodos , Variación Genética , Mannheimia haemolytica/aislamiento & purificación , Pasteurella/aislamiento & purificación , Filogenia , Serotipificación/veterinariaRESUMEN
The XbaI digestion patterns of chromosomal DNA of 42 aeromonads isolated from French breeding snails during a new epizootic disease, which rapidly progressed to death during the summer of 1994, were analyzed by pulsed-field gel electrophoresis. Biochemical identification to species level was also performed. Interestingly, we found that 76% of the aeromonads isolated from diseased snails clustered into a unique pulsotype (P1) whatever their geographic origin, and were assessed to belong to Aeromonas hydrophila. Other strains belonged to Aeromonas caviae or remained unspecified. Our results provide retrospective supplementary epidemiological evidence for implication of A. hydrophila strains in the snail summer disease.
Asunto(s)
Aeromonas/clasificación , Aeromonas/aislamiento & purificación , Crianza de Animales Domésticos , Técnicas de Tipificación Bacteriana , Caracoles Helix/microbiología , Aeromonas/genética , Aeromonas hydrophila/clasificación , Aeromonas hydrophila/genética , Aeromonas hydrophila/aislamiento & purificación , Animales , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Electroforesis en Gel de Campo Pulsado/métodos , FranciaRESUMEN
Rapid immunomigration on a membrane was applied to the diagnosis of canine parvovirus (CPV) in 128 samples of faeces containing four strains of parvovirus (two CPV-2a strains, including one vaccine strain, and two CPV-2b strains). The results were compared with the results of haemagglutination and ELISA sandwich techniques. The new test was quick and easy to use, and made it possible to identify both the CPV-2a and CPV-2b strains. Its detection thresholds per gram of faeces corresponded to specific haemagglutination titres of between 320 and 640 and a virus titre of between 10(4) and 10(5) CCID50 (dose required to infect 50 per cent of cell cultures).
Asunto(s)
Enfermedades de los Perros/diagnóstico , Infecciones por Parvoviridae/veterinaria , Parvovirus Canino/aislamiento & purificación , Juego de Reactivos para Diagnóstico/veterinaria , Animales , Perros , Ensayo de Inmunoadsorción Enzimática/veterinaria , Heces/virología , Pruebas de Hemaglutinación/normas , Pruebas de Hemaglutinación/veterinaria , Infecciones por Parvoviridae/diagnóstico , Parvovirus Canino/inmunología , Valor Predictivo de las Pruebas , Juego de Reactivos para Diagnóstico/normas , Sensibilidad y EspecificidadRESUMEN
Thirty-two faecal samples from various pet chelonians were bacteriologically examined using various combinations of selective media for Salmonella detection. Strains identified as Salmonella were clustered by rRNA gene restriction pattern (ribotyping) analysis prior to serological typing. The combination of selenite broth and Rambach or Salmonella-Shigella agars gave the maximum rate of Salmonella recovery. Of the 32 samples examined, 13 (40%), were positive for Salmonella. Five serovars were identified, Muenchen, Rubislaw, Newport, Ferruch and a non-motile O:4,5,12, with Salmonella Muenchen the most common. This result indicates that biochemical characterization combined with ribotyping prior to serotyping can contribute to Salmonella detection on a large scale.