RESUMEN
BACKGROUND: Cystic fibrosis is a lethal autosomal recessive disorder usually associated with lung disease, pancreatic insufficiency and high sweat chloride levels. CLINICAL CASE: A patient admitted to Le Bonheur Children's Medical Center (LBCMC, Memphis, TN) showed symptoms of meconium ileus which required exploratory laparotomy, bowel resection and ileostomy. Genotyping showed DeltaF508/I1027T on one chromosome and S1118F on the other. Sweat testing on three different occasions gave negative and intermediate results (22.7, 24.6 mmol/L; 55.1, 58.6 mmol/L and 55.1, 58 mmol/L) and pancreatic elastase testing showed normal levels. OBJECTIVE: To characterize S1118F-CFTR mutation at a molecular level to help understand the associated CF-phenotype. METHODS: Molecular characterization of S1118F-CFTR mutant was studied in HEK-293 cells at 37 degrees C. Various biochemical methods such as Western blotting, real-time PCR, Pulse chase labeling and iodide efflux assay were employed. RESULTS: S1118F-CFTR makes less than 10-15% of mature CFTR (band C) compared to WT-CFTR. The mRNA levels of S1118F-CFTR and WT-CFTR are comparable. S1118F-CFTR is functional but shows about 10-15% of WT-CFTR activity. S1118F-CFTR shows impaired maturation and CF-correctors can increase the amount of mature and functional CFTR by three- to fourfold. CONCLUSION: S1118F-CFTR shows impaired maturation and an individual with S1118F-CFTR paired with DeltaF508-CFTR exhibits atypical CF symptoms with intermediate sweat chloride level and meconium ileus despite documented pancreatic sufficiency.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Mutación , Western Blotting , Células Cultivadas , Cloruros/análisis , Insuficiencia Pancreática Exocrina/genética , Femenino , Predisposición Genética a la Enfermedad , Variación Genética , Genotipo , Humanos , Ileus/genética , Masculino , Fenotipo , Probabilidad , ARN/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sudor/química , Sudor/metabolismoRESUMEN
Apoptosis of murine and human macrophages induced by group B Streptococcus agalactiae (GBS) is likely an important virulence mechanism that is used by the bacteria to suppress the host immune response and to persist at sites of infection. The mechanisms by which GBS induces apoptosis are, however, largely unknown. In this study, we report that in murine macrophages GBS induces unique changes in the regulation and localization of the apoptotic regulators Bad, 14-3-3, and Omi/high-temperature requirement A2 and leads to the release of cytochrome c and the activation of caspase-9 and caspase-3. Furthermore, inhibition of caspase-3 impaired GBS-induced apoptosis of macrophages. The ability to modulate the activity of effector caspases may therefore represent an unexploited avenue for therapeutic intervention in GBS infections.